WO2022251796A1 - Systems and methods for desulfurization, denitrogenation, deoxygenation, hydrogenation, and dehydrogenation with alkali metal containing materials - Google Patents

Systems and methods for desulfurization, denitrogenation, deoxygenation, hydrogenation, and dehydrogenation with alkali metal containing materials Download PDF

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WO2022251796A1
WO2022251796A1 PCT/US2022/072449 US2022072449W WO2022251796A1 WO 2022251796 A1 WO2022251796 A1 WO 2022251796A1 US 2022072449 W US2022072449 W US 2022072449W WO 2022251796 A1 WO2022251796 A1 WO 2022251796A1
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desulfurization
alkali metal
bond
dbt
carbon
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PCT/US2022/072449
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French (fr)
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Fei CHANG
Hui Zhou
Alexey FEDOROV
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Fuzionaire, Inc.
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Publication of WO2022251796A1 publication Critical patent/WO2022251796A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B59/00—Introduction of isotopes of elements into organic compounds ; Labelled organic compounds per se
    • C07B59/001—Acyclic or carbocyclic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/02—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the alkali- or alkaline earth metals or beryllium
    • B01J23/04—Alkali metals
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G11/02—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils characterised by the catalyst used
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G3/00—Production of liquid hydrocarbon mixtures from oxygen-containing organic materials, e.g. fatty oils, fatty acids
    • C10G3/42—Catalytic treatment
    • C10G3/44—Catalytic treatment characterised by the catalyst used
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/02—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing
    • C10G45/04—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing characterised by the catalyst used
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/18—Carbon
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/20—Characteristics of the feedstock or the products
    • C10G2300/201—Impurities
    • C10G2300/202—Heteroatoms content, i.e. S, N, O, P

Definitions

  • the present invention generally relates to systems and methods for desulfurization, denitrogenation, deoxygenation, hydrogenation, and dehydrogenation with alkali metal containing materials; and more particularly to silane-free and transition metal free systems and methods for reductive cleavage of C-S, C-N, C-O, C-C, and C-H bonds with carbon-supported alkali metal hydrides, carbon-supported alkali metal, and/or molecular compunds of alkali metals.
  • Desulfurization (DS) and hydrodesuifurization (HDS) are processes by which sulfur-containing impurities can be removed from petroleum streams, for example using a heterogeneous, sulfided transition metal catalyst under high Hs pressures and temperatures (typical for HDS).
  • a major obstacle that remains is the desulfurization of highly refractory sulfur (S) - containing heterocycles that are naturally occurring in fossil fuels.
  • Homogeneous hydrodesuifurization strategies using well-defined molecular catalysts have been designed to target these recalcitrant S - heterocycles.
  • the formation of stable transition metal sulfide complexes following C-S bond activation has prevented catalytic turnover, and lack of affordable reactants and reaction conditions have hindered wide applications.
  • Denitrogenation (DM) and hydrodenitrogenation (HDN) are processes for the removal of nitrogen from petroleum streams.
  • the hydrodenitrogenation process in a refinery removes nitrogen from the feedstocks, which often occurs concurrently with removal of sulfur from the feedstock.
  • Organonitrogen compounds, even though they may occur at low levels, are undesirable because they cause poisoning of downstream catalysts.
  • organonitrogen compounds upon combustion, organonitrogen compounds generate NOx, a pollutant.
  • Typical catalysts for the denitrogenation of petroleum streams can include molybdenum disulfide or tungsten disulfide supported on alumina promoted by cobalt or nickel.
  • Deoxygenation (DO) and hydrodeoxygenation (HDO) are processes for removing oxygen from oxygen-containing compounds.
  • Deoxygenation can be a promising technology to remove the oxygen from biomass-derived streams, for example obtained after pyrolysis.
  • One obstacle is to find selective catalysts to minimize the use of hydrogen while maintaining the aromatic functionality of lignin.
  • Typical catalysts for the deoxygenation of petroleum streams can include molybdenum disulfide or tungsten disulfide supported on alumina promoted by cobalt or nickel.
  • Dehydrogenation is a process by which hydrogen is removed from an organic compound to form a new chemical (e.g., to convert saturated compounds into unsaturated compounds). It is the reverse process of hydrogenation. It can be used to produce alkenes by the dehydrogenation of alkanes. Dehydrogenation products may include ethene, propene, and styrene. It is a challenging reaction as the fouling and deactivation of many catalysts may take place, in particular via coking, which is the dehydrogenative polymerization of organic substrates. BRIEF SUMMARY OF THE INVENTION
  • Many embodiments are directed to systems and methods for desulfurization with carbon-supported alkali metal hydrides and/or molecular compounds of alkali metals.
  • Several embodiments provide catalytic hydrogenation capabilities with carbon-supported alkali metal hydrides.
  • carbon-supported alkali metal hydrides can participate in denitrogenation, deoxygenation, and dehydrogenation processes.
  • a number of embodiments provide that carbon-supported alkali metal hydrides and carbon-supported alkali metal may have similar reactivities during dehydrogenation processes for propane.
  • An embodiment of the invention includes a system for desulfurization, denitrogenation, deoxygenaiion, dehydrogenation, and hydrogenation comprising at least one alkali metal hydride of a formula MaHb, and a carbon substrate.
  • M is selected from the group consisting of lithium, sodium, and potassium, and a molar ratio a/b between M and H is: G ⁇ a/b ⁇ 1 ; the at least one alkali metal hydride is supported on the carbon substrate; and the system reductiveiy cleaves at least one C-X bond in an organic substrate, where X is selected from the group consisting of S, N, O, H, and C.
  • the system is free of transition metal and free of silane.
  • the system reductiveiy cleaves at least one C-S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound.
  • the system reductiveiy cleaves at least one C-S bond in a S-containing organic substrate selected from the group consisting of dibenzothiopbene, 4,6-dimethyidibenzothiophene, 4,6-diethyldibenzothiophene, 4- methyidibenzothiophene, dibenzothiopbene suifone, diphenyl sulfide, 2- phenyithiophenol, polyphenylene sulfide, and aliphatic di-n-octyi sulfide.
  • a S-containing organic substrate selected from the group consisting of dibenzothiopbene, 4,6-dimethyidibenzothiophene, 4,6-diethyldibenzothiophene, 4- methyidibenzothiophene, dibenzothiopbene suifone, diphenyl sulfide, 2- phenyithiophenol, polyphenylene s
  • the desulfurization occurs at a temperature between 50 °C and 165 °C.
  • system reductiveiy cleaves at least one C-N bond in a N-containing heterocyclic compound.
  • the N-containing heterocyclic compound is 9- phenyl-carbazole.
  • the system reductively cleaves at least one C-0 bond in a G-coniaining heterocyclic compound.
  • O-containing heterocyclic compound is dibenzofuran.
  • the system reductively cleaves at least one C-H bond and removes at least one H in propane.
  • the alkali metal is potassium and potassium hydride on carbon decomposes to potassium on carbon during propane dehydrogenation.
  • the potassium hydride on carbon has a weight percentage between 20% and 30%.
  • the at least one alkali metal hydride is potassium hydride and the carbon substrate is graphite.
  • the organic solvent is selected from the group consisting of mesityiene, cyclohexane, toluene, and /?-octane.
  • the desulfurization, denitrogenation, and deoxygenation occur under hydrogen gas or an inert gas selected from the group consisting of argon, nitrogen, and helium.
  • the dehydrogenation occurs under an inert gas selected from the group consisting of argon, nitrogen, and helium.
  • the system cleaves at least one C-C bond in aromatic heterocyclic compounds and catalyticaily hydrogenizes at least one unsubstituted phenyl ring.
  • the unsubstituted phenyl ring is biphenyl.
  • the system cleaves at least one C-C bond and catalyticaily hydrogenates at least one carbon triple bond in an aikyne to form at least one carbon double bond in an olefin.
  • the aikyne is pbenyiacety!ene
  • the hydrogenation occurs under hydrogen gas.
  • Another embodiment includes a system for dehydrogenation comprising at least one alkali metal, and a carbon substrate.
  • the at least one alkali metal is selected from the group consisting of lithium, sodium, and potassium; the carbon substrate supports the at least one alkali metal; and the system reductively cleaves at least one C- X bond in an organic substrate, where X is H or C.
  • the organic substrate is propane.
  • a dehydrogenation temperature is at least 400 °C.
  • the dehydrogenation occurs under an inert gas selected from the group consisting of nitrogen, helium, and argon.
  • the alkali metal is potassium and the carbon substrate is graphite.
  • the potassium on the carbon substrate has a weight percentage between 20% and 30%
  • a further embodiment includes a system for desulfurization comprising a molecular compound comprising at least one alkali metal selected from the group consisting of lithium, sodium, and potassium.
  • system reductively cleaves at least one C-S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound.
  • the molecular compound is potassium bis(trimethylsilyl)amide.
  • the system if free of silane and free of transition metal.
  • a further yet embodiment comprises an organic solvent, wherein the organic solvent is selected from the group consisting of mesitylene, toluene, and n - octane.
  • the system reductively cleaves at least one C-S bond in a S-containing organic substrate selected from the group consisting of dibenzothiophene, 4,6-dimethyldibenzothiophene, and 4,6-diethyldibenzothiophene.
  • FIG. 1 illustrates an industrial DS process with ColVloSx/AhCb as catalyst in accordance with prior art.
  • FIG. 2 illustrates chemical structures of DBT and DBT derivatives.
  • FIG. 3 illustrates the reaction scheme of desulfurization of DBT derivatives using KOSi reaction in accordance with prior art.
  • FIG. 4 illustrates the reaction scheme of KH partial desulfurization reaction in accordance with prior art.
  • FIG. 5 illustrates a reaction scheme of desulfurization of DBT derivatives with carbon-supported potassium hydride in accordance with an embodiment of the invention.
  • FIG. 6 illustrates desulfurization of DBT in accordance with an embodiment of the invention.
  • FIGs. 7 A - 7D illustrate DS reactions under different conditions in accordance with an embodiment of the invention
  • FIG. 8 illustrates XRD of KH/C collected after the desulfurization of dibenzothiophene in mesitylene in accordance with an embodiment of the invention.
  • FIG. 9 illustrates distribution of deuterated products of desulfurization of DBT on KH/C or K/C in to!uene-ds in accordance with an embodiment of the invention,
  • FIG. 10 illustrates distribution of deuterated products of hydrogenation of biphenyl in different conditions in accordance with an embodiment of the invention.
  • FIG. 11 illustrates distribution of deuterated products of deoxygenation of dibenzofuran on KH/C in toluene-da in accordance with an embodiment of the invention.
  • FIG. 12 illustrates desulfurization of DBT with KHMDS in accordance with an embodiment of the invention.
  • FIG. 13 illustrates a DS reaction scheme of DBT derivatives, including alkylated DBTs, in accordance with an embodiment of the invention.
  • FIG. 14 illustrates a desulfurization reaction scheme of aliphatic di-n-octyl sulfide in accordance with an embodiment.
  • FIG. 15 illustrates a desulfurization scheme of 4,6-Me2DBT and aliphatic di ⁇ n ⁇ octyl sulfide in accordance with an embodiment of the invention
  • FIG. 16 illustrates a desulfurization reaction scheme of dibenzothiophene su!fone in accordance with an embodiment of the invention
  • FIG. 17 illustrates a desulfurization reaction scheme of diphenyl sulfide in accordance with an embodiment.
  • FIG. 18 illustrates a desulfurization reaction of 2-phenylthiophenol in accordance with an embodiment.
  • FIG. 19 illustrates a desulfurization reaction of polyphenylene sulfide in accordance with an embodiment of the invention.
  • FIG. 20 illustrates desulfurization of alkylated DBT with KH!VIDS in accordance with an embodiment of the invention.
  • FIGs, 21 A - 21 B illustrate reaction schemes of DO of dibenzofuran with KH/C in accordance with an embodiment.
  • FIG. 22 illustrates a reaction scheme of denitrogenation of 9-pheny!carbazole in accordance with an embodiment of the invention.
  • FIG. 23 illustrates main target reaction and side reactions of PDF! in accordance with prior art.
  • FIGs. 24A - 24D illustrate conversion and product formation rates during propane dehydrogenation on KIC at about 500 °C in accordance with an embodiment of the invention.
  • FIGs, 25A - 25D illustrate conversion and product yields during propane dehydrogenation on K/C at about 400 °C in accordance with an embodiment of the invention.
  • FIGs, 28A - 28D illustrate conversion and product yields during propane dehydrogenation on 3Gwt.% KH/C at about 400 °C in accordance with an embodiment of the invention,
  • FIGs. 27A - 27D illustrate conversion and product yields during propane dehydrogenation on 20wt.% KH/C at about 400 °C in accordance with an embodiment of the invention.
  • FIGs. 28A - 28D illustrate conversion and product yields during propane dehydrogenation on 10wt% KH/C at about 400 °C in accordance with an embodiment of the invention.
  • FIGs, 29A - 29D illustrate conversion and product yields during propane dehydrogenation on carbon at about 400 °C in accordance with an embodiment of the invention.
  • FIGs. 30A - 30D illustrate conversion and product yields during propane dehydrogenation on carbon at about 500 °C in accordance with an embodiment of the invention.
  • FIG. 31 illustrates a reaction scheme of hydrogenation of biphenyl to phenylcyclohexane in accordance with an embodiment of the invention.
  • FIG. 32 illustrates a reaction scheme of hydrogenation of phenylcyclohexane to bicyclohexane in accordance with an embodiment of the invention.
  • FIG. 33 illustrates a reaction scheme of hydrogenation of alkyne to alkene in accordance with an embodiment of the invention
  • DS desulfurization
  • DN denitrogenation
  • DO deoxygenation
  • DH dehydrogenation
  • catalytic hydrogenation with alkali metal containing materials Many embodiments provide DS processes with alkali metal hydrides systems and/or molecular compounds of alkali metals. Some embodiments provide DN, DO, DH, and hydrogenation processes with alkali metal hydrides systems. Several embodiments provide that the DS, DN, DO, DH, and catalytic hydrogenation processes are free of transition metals and are free of silane.
  • alkali metal hydrides can reductive!y cleave C-8, C ⁇ N, C-O, C-C, and/or C-H bonds.
  • molecular compounds containing alkali metals can reductive!y cleave C-S bonds.
  • alkali metal hydrides can initiate catalytic hydrogenation processes.
  • alkali metal systems can participate in DH processes.
  • alkali metal hydride including (but not limited to) potassium hydride (KH), sodium hydride (NaH), and lithium hydride (LiH) in the DS, DM, DO, DH, and catalytic hydrogenation processes.
  • alkali metal and/or alkali metal hydride can be supported on carbon-based substrate as the reactant.
  • metallic alkali metal can be mixed with a carbon-supported substrate including (but not limited to) graphite to form alkali metal on carbon (M/C).
  • metallic alkali metal can be mixed with a carbon-based substrate including (but not limited to) graphite substrate in the presence of hydrogen to form alkali metal hydride (MH) on carbon (MH/C).
  • any of a variety of carbon substrate can be utilized as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
  • alkali metal-containing molecular compounds including (but not limited to) potassium bis(trimethyisilyi)amide (KHMDS) can be used to replace silane in DS reactions.
  • KHMDS potassium bis(trimethyisilyi)amide
  • any of a variety of alkali metai molecular compound can be utilized as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
  • alkali metal hydrides and/or molecular compounds of alkali metals to remove sulfur-containing impurities during desulfurization processes.
  • Several embodiments provide cleavage of C-S bonds in various organosulfur substrates under mild conditions including (but not limited to) lower reaction temperatures and shorter reaction time.
  • sulfur-containing impurities include (but are not limited to) sulfur-containing heterocycies and sulfur-containing aliphatic compounds.
  • sulfur-containing heterocycies include (but are not limited to): dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,8 ⁇ IVIe2DBT), 4,6-dietby!dibenzothiophene (4,6-Et2DBT). 4-metbyldibenzothiophene (4-MeDBT), dibenzothiophene sulfone (DBT-SO2), diphenyl sulfide, 2-phenylthiophenol, and polyphenylene sulfide.
  • sulfur-containing aliphatic compounds include (but are not limited to) aliphatic di-n-octy! sulfide.
  • any of a variety of sulfur containing compound can be utilized during desulfurization process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
  • alkali metal hydrides including (but not limited to) carbon-supported KH (KH/C) can participate in denitrogenation processes by cleaving C-N bonds and remove nitrogen from nitrogen- containing heteroaromatics including (but not limited to) 9-phenyl-carbazole.
  • any of a variety of nitrogen containing compound can be utilized during denitrogenation process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
  • Several embodiments provide deoxygenation of oxygen-containing heteroaromatic compounds including (but not limited to) dibenzofuran with KH/C.
  • KH/C can cleave C-0 bonds in heteroaromatic compounds in accordance with some embodiments.
  • any of a variety of oxygen containing compound can be utilized during deoxygenation process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
  • K/C and/or alkali metal hydrides including (but not limited to) KH/C can be used in dehydrogenation processes of compounds including (but not limited to) propane.
  • K/C and/or KH/C can cleave C-H bonds during dehydrogenation processes.
  • KH/C may act as a precursor and decompose to K/C at propane dehydrogenation (PDH) temperatures of at least 400 °C.
  • PDH propane dehydrogenation
  • KH/C can participate in catalytic hydrogenation processes and provide hydrogen to compounds including (but not limited to) a!kynes and unsubstituted phenyl rings.
  • KH/C can cleave C-C bonds during hydrogenation processes.
  • KH/C can convert alkynes to olefins, without forming significant amounts of alkanes.
  • KH/C can catalyze hydrogenation of unsubstituted phenyl rings including (but not limited to) biphenyl.
  • phenyicyclohexane can be a secondary product formed via hydrogenation of biphenyl.
  • the subsequent hydrogenation of phenyicyclohexane to bicyciohexane on KH/C can proceed under a higher pressure of hydrogen.
  • alkali metal including (but not limited to) K can be mixed with H in a 1 :1 ratio in the DS, DM, DO, DH, and hydrogenation processes.
  • the molar ratio between K and H can be greater than 0 and less than or equal to 1. Any ratio between K and H greater than 0 and no greater than 1 in accordance with certain embodiments may work in DS, DM, DO, DH, and hydrogenation processes.
  • K/C (the ratio between K and H is 1 :0) can participate in DS, DN, DO, and hydrogenation processes, but the activities of KH/C and K/C differ.
  • K/C and KH/C may have similar activities during DH processes in accordance with several embodiments. Many embodiments provide that the amount of KH/C used in the reactions can affect the conversion efficiency and the yields of products. In a number of embodiments, KH/C may have higher conversion yields of DBT and DBT derivatives than KH.
  • DS, DM, and DO reactions can take place under an inert gas including (but not limited to) argon, helium, and nitrogen, or under hydrogen (H 2 ) gas.
  • DS processes under H 2 pressure can stabilize KH/C.
  • KH/C may participate in catalytic hydrogenations of aromatic substrates including (but not limited to) biphenyl to form phenyicyclohexane.
  • lower hydrogen pressure may lead to a lower desulfurization efficiency.
  • Methane pretreated K/C in accordance with several embodiments may have a higher DS activity than K/C and/or KH/C at low temperatures including (but not limited to) about 30 °C.
  • DH reactions can take place under an inert gas including (but not limited to) argon, helium, and nitrogen.
  • Fossil fuels contain naturally occurring organosulfur impurities, with quantities varying depending on the type of feedstock. These sulfur-containing organic small molecules can poison catalytic converters and generate polluting sulfur dioxides when combusted.
  • Desulfurization (DS) is the industrial process by which sulfur impurities are removed from petroleum fractions prior to their use as fuels. DS may rely on heterogeneous catalysts such as M0S2/AI2O3 promoted with cobalt or nickel. These catalysts are typically utilized at about 400 °C under h1 ⁇ 2 pressures of up to 100 bar. (See, e.g., J. N. D.
  • HDS can be performed by treating petroleum with H 2 at high pressures and temperatures (for example, H 2 pressures about 150-2,250 psi and about 400 °C) over heterogeneous catalysts such as cobalt-doped molybdenum sulfide supported on alumina (CoMoSx/v-AteCh) (See, e.g., Prins, R. et al., Catai. Today , 2008, 111 , 84-93; the disclosure of which is incorporated herein by reference).
  • FIG. 1 illustrates an industrial DS process with CoMoSx/AbOs as catalyst.
  • FIG. 2 illustrates chemical structures of DBT and DBT derivatives (DBT-SO, DBT-SOa, 4-MeDBT, and 4,6-iyie 2 DBT). Because HDS is energy intensive, there is a need in alternative routes that are more environmentally friendly.
  • alkyl Grignard reagents or an organosilane (such as EtMe 2 8iH) in a combination with a Ni-based catalyst have been applied for DS of aryl methyl thioethers.
  • organosilane such as EtMe 2 8iH
  • Alkali metals such as Li, Na, K
  • desulfurization of petroleum residues and coal have been used in DS reactions as well, including desulfurization of petroleum residues and coal.
  • Table 1 lists experiment results from literatures of the desulfurization of DBT and its derivatives using Li and Na metals.
  • the molar ratio refers to the molar ratio between the substrate (S) and the alkali metal (Li/Na).
  • RT refers to room temperature ranging from 20 °C to 25 °C.
  • Toutov, A.A., et al. have reported a potassium (K) alkoxide (G)/hydrosilane (Si)-based (‘KOSi’) system that desulfurizes refractory sulfur heterocycles (See, e.g., Toutov, A. A., et al., Nature Energy, 2017, 2, 17008; the disclosure of which is incorporated herein by reference).
  • KOSi potassium alkoxide
  • Si hydrosilane
  • the DS method that operates under KOSi (KOtBu/silane) conditions may not require the use of organometallic complexes or inorganic transition metal species.
  • FIG. 3 illustrates the reaction scheme of KOSi desulfurization reaction.
  • the DS reactions occur at about 165 °C for about 40 hours and utilize three equivalents of the KO-fBu/EfsSiH reagent per one mol of a substrate.
  • the Grubbs-Stoltz reagent can have a high DS efficiency with alkylated dibenzothiophenes, similar to the efficiency when using the alkali metals.
  • the KO-fBu/EtaSiH reagent allows to lower the content of 4,8 ⁇ Me2DBT in the spiked diesel from about 10000 ppm to about 2.4 ppm, although in this case a 0.5 M concentration (i.e,, a large excess) of KO-tBu and Et 3 SiH has been used.
  • the application of KO-tBu with Et 3 SiH for DS may provide, at least initially, a homogeneous reaction mixture. Unfortunately, this leads to a high concentration of K and Si species in solution after the DS reaction, which may hinder the applicability of this method for the DS of fuels.
  • KOtBu and EtsSiH used in the KOSi method are not economical to apply to industrial applications. Cheaper desulfurization conditions for HDS processes may be needed for practical applications.
  • FIG. 4 illustrates the reaction scheme of KH partial desulfurization reaction.
  • KH can be supported by a substrate containing carbon including (but not limited to) graphite to form KH on graphite (KH/C) in accordance with certain embodiments.
  • carbon-supported potassium hydride (KH/C) enables reductive desulfurization of C-S bonds in organosulfur substrates.
  • KH/C can act as a stoichiometric reagent in desulfurization.
  • KH/C can act as a reductant to desulfurize suifur-containing organic molecules including (but not limited to) dibenzothiophene and/or dibenzothiophene derivatives.
  • KH/C is able to achieve ultra-deep desulfurization.
  • KH/C can reduce sulfur content of dibenzothiophene and dibenzothiophene derivatives to low ppm levels.
  • potassium-containing molecular compounds including (but not limited to) potassium bis(trimethy!silyl)amide (KHMDS) can be used to replace silane and/or transition metals in DS reactions.
  • desulfurization processes can occur under mild conditions including (but not limited to) temperature starting from about 50 °C and less than about 165 °C. Yields of desulfurized hydrocarbons obtained using KH/C in hydrocarbon solvents in accordance with some embodiments can exceed about 90%. In several embodiments, at least 97% of DBTs can be converted at no higher than about 165 °C less than about 6 hours. Some embodiments provide the conversion of DBTs at about 165 °C takes place in about 3 hours to about 6 hours. The yields of respective biphenyls from DBTs conversions in accordance with certain embodiments can be from about 84% to about 95%.
  • no greater than 15% excess of KH per a C-S bond is applied in the DBTs conversion.
  • the high yields of desulfurization can be achieved with about 15% molar excess of KH per C-S bond, without leaching of K into solution.
  • Several embodiments provide conversion of DBT derivatives including (but not limited to) 4,6-Me2DBT with carbon-supported KH/C in mild conditions.
  • the conversion of 4,6-IVie2DBT can take place at not higher than about 165 °C and no greater than about 20 hours.
  • KH/C enables to lower the concentration of 4,8- MeaDBT in the mesityiene solution from about 1000 ppm to less than about 3 ppm.
  • the monomethyl DBTs, dimethyl DBTs, and diethyl DBTs may produce biaryis during DS.
  • KH/C enables chemoselective DS of diaryl thioethers in preference to diaikyl thioethers.
  • KH/C can catalyze hydrogenation of an unsubstituted phenyl ring in biphenyl derivatives to form a cyclohexyl group under about 10 bar of H 2 .
  • KH/C may remove other heteroatoms using dibenzofuran and 9-phenylcarbazole that undergo deoxygenation and denitrogenation reactions.
  • incorporation of deuterium into desulfurized products can take place when KH/C is applied in toluene-ds.
  • FIG. 5 illustrates a reaction scheme of desulfurization with carbon-supported potassium hydride in accordance with an embodiment of the invention.
  • Organosuifur substrate 501 can be DBT or alkylated DBTs.
  • R 1 and R 2 groups in the organosuifur substrate 501 can be hydrogen or alkyl groups.
  • the desulfurization takes place under a temperature of less than about 165 °C.
  • the organosuifur substrate 501 can be reduced and the C-S bond can be removed.
  • FIG. 8 illustrates desulfurization of DBT in accordance with an embodiment of the invention.
  • DBT 801 can be reduced and form biphenyl 802 and phenylcyclohexane 803 at different selectivity and/or yields respectively under various reaction conditions. Different DBT desulfurization conditions result in different conversion efficiency of DBT.
  • DBT desulfurization conditions can include, mesityiene as a solvent, reaction temperature between about 50 °C and about 185 °C, reaction time from about 1 hour to about 40 hours, under about 10 bar Ar or about 10 bar H 2 , with KH/C or K/C.
  • Several embodiments provide DBT reaction conditions for DS using KH/C compared to K/C and commercial KH.
  • a 0.03 M solution of DBT in mesityiene can be stirred for about 20 hours with about 1.15 equiv. of KH/C or K/C per C--S bond of DBT while the temperature varies from about 50 °C to about 165 °C.
  • Molar ratio of K (in KH/C or K/C) to DBT can be about 2.3 : 1.
  • a standard (tridecane) can be added after the reaction, the reaction mixture can be filtered and conversion of DBT and yields of formed products can be quantified by gas chromatography-mass spectrometry (GC-MS).
  • FIG. 7 A illustrates DS reaction with KH/C and K/C under about 10 bar Ar at temperature between about 50 °C and about 185 C C in accordance with an embodiment of the invention.
  • DBT conversion on K/C is shown in curve 701.
  • DBT conversion on KH/C is shown in curve 702
  • Yield of biphenyl on KH/C is shown in curve 703.
  • Yield of biphenyl on K/C is shown in curve 704.
  • DS of DBT provides biphenyl as the only product at about 50 °C, obtained in about 8% yield (703) at about 11 % conversion of DBT (702).
  • the lower yield of biphenyl with KH/C at 185 °C reiative to 130 °C may be due to the increased reactive adsorption of DBT (or intermediates to form biphenyl) onto the KH/C material, possibly owing to a partial decomposition of KH to K and hte on KH/C at the higher used reaction temperature.
  • Reactive adsorption of DBT can be stronger on K/C compared to KH/C since below 80 °C.
  • conversion of DBT on K/C is about two times higher than that on KH/C (62% and 32%), yet the yields of biphenyl are comparable (25% and 27%).
  • a similar trend is also observed at 130 °C and 165 °C.
  • K/C shows a complete conversion of DBT but lower yields of biphenyl compared to KH/C, likely owing to a higher amount of species formed due to the reactive adsorption of DBT on K/C (703 and 704).
  • the decomposition of KH/C to K/C after treating KH/C at about 165 °C for about 20 hours in mesitylene is consistent with the lack of detected Ha in an Ar ⁇ TPD experiment of the dried recovered material.
  • FIG. 7B illustrates DS reaction on KH/C under about 10 bar H 2 at temperature between about 50 °C and about 165 °C in accordance with an embodiment of the invention.
  • DBT conversion on KH/C is shown in curve 705.
  • Yield of biphenyl on KH/C is shown in curve 706.
  • Yield of phenylcyclohexane on KH/C is shown in curve 707.
  • the yield of phenylcyclohexane (707) gradually increases from about 0% to about 12% before raising sharply to about 84% at about 165 °C.
  • biphenyl (706) increases from about 9% at about 50 °C to about 54% at about 130 °C and then it decreases to about 0%. This is probably due to the hydrogenation of biphenyl to phenylcyclohexane above 130 °C.
  • FIG. 7 C illustrates DS reaction at various time points with KH/C under about 10 bar H 2 at about 100 °C.
  • DBT conversion on KH/C is shown in curve 711.
  • Yield of biphenyl on KH/C is shown in curve 712.
  • Yield of phenyl cyclohexane on KH/C is shown in curve 713.
  • biphenyl and phenylcyclohexane form in about 59% and 7% yields respectively (712 and 713), at about 79% conversion of DBT (711 ).
  • FIG. 7D illustrates DS reaction at various time points with KH/C under about 10 bar H 2 at about 165 °C.
  • DBT conversion on KH/C is shown in curve 714.
  • Yield of biphenyl on KH/C is shown in curve 716.
  • Yield of phenyl cyclohexane on KH/C is shown in curve 715.
  • the conversion of DBT reaches about 82% after about 1 hour at about 165 °C (714), and yields of biphenyl and phenylcyclohexane are about 61 % and 8% respectively (715 and 716).
  • the better reactivity of KH/C may be due to smaller particle sizes of KH in KH/C relative to the commercial KH.
  • a smaller particle sizes means a larger surface area, i.e., a higher contact area with molecules in solution (solvent and a substrate for DS)
  • Certain embodiments provide that the better reactivity of KH/C may also be related to a support effect. If the DS reaction involves an electron transfer from KH/C to the S-containing substrate molecule, or to a solvent molecule first, and then to the substrate, this transfer may take place from the adsorption sites of the C support, and not from the adsorption sites on KH, provided that electrons can flow from KH to the C support (which is conductive).
  • So support may function as an electron transfer reagent.
  • the DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time about 20 hours, under about 10 bar Ar or about 10 bar Hs, with KH/C or commercial KH.
  • the ratio of KH/C or KH is about 1.15 equivalent per C-S bond.
  • DBT can be reduced and form biphenyl at different selectivity and/or yields under various reaction conditions.
  • Reaction conditions including (but not limited to) temperature and reaction time can influence selectivity and/or yield of biphenyl and conversion of DBT.
  • biphenyl is the only product detected by gas chromatography (GC) when reaction is conducted under inert gas.
  • GC gas chromatography
  • KH/C might be a potent hydrogen donor for stoichiometric desulfurization of DBT.
  • lower hydrogen pressure may decrease the hydrogenation rate of biphenyl to phenyicyclohexane.
  • Lower hydrogen pressure including (but not limited to) 2 bar and 5 bar may lower the yield of phenyicyclohexane on KH/C after about 20 hours to about 7% (at 2 bar) or about 38% (at about 5 bar).
  • Biphenyl can be the major product formed at the complete conversion of DBT.
  • Table 3 lists conversion percentage and yields at various hydrogen partial pressure during the desulfurization of DBT on KH/C.
  • the DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time about 20 hours, with KH/C.
  • the ratio of KH/C is about 1.15 equivalent per C-S bond. Reactions run under a constant total pressure of 10 bar but with different H 2 partial pressures. Total pressure can be balanced by Ar.
  • phenyicyciohexane can be a secondary product formed via hydrogenation of biphenyl.
  • Several embodiments provide that the subsequent hydrogenation of phenyicyciohexane to bicyclohexane can proceed at a higher pressure of hydrogen.
  • Catalytic hydrogenation processes with KH/C are discussed in details in a following section.
  • FIG. 8 illustrates XRD of KH/C collected after the desulfurization of dibenzothiophene in mesitylene in accordance with an embodiment of the invention. Reaction can be performed at about 185 °C in H 2 for about 20 hours. XRD of KH/C at about 185 °C, about 20 hour, about 10 bar H 2 , shows peaks attributed to K2S on C. HADDF-8TEM images and EDX mappings show the high dispersion of K and S on the KH/C as well as on the K/C (165 °C, 20 h, 10 bar Ar) after the desulfurization reaction.
  • the amount of KH used in the DS reactions can affect the conversion of DBT and the yields of products.
  • decreasing by two fold the amount of used KH per mol of DBT such as from about 2.3:1 to 1.15:1
  • the conversion of DBT can lower the conversion of DBT from complete to about 48% (185 °C, 20 h and 10 bar H 2 ).
  • the distribution of products may change as well.
  • KH per mol of DBT KH/C : DBT
  • the yield of phenyicyciohexane may change from about 84% (as a sole product) to about 5%.
  • Biphenyl increases to about 40% with the 1.15:1 ratio of KH/C: DBT.
  • the 1.15:1 molar ratio of KH/C:DBT is used, most of KH/C may be converted to K 2 8/C, and K 2 S/C can be inactive in hydrogenation of biphenyl to phenylcydohexane.
  • Table 4 lists dependence of the product selectivity on the ratio of DBT to KH/C.
  • the reactions use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under about 10 bar H 2 , with KH/C.
  • spent KH/C is less effective in converting DBT in DS processes.
  • Spent KH/C can be recovered and treated under 100 bar of H 2 at about 200 °C for 20 hours.
  • the use of spent KH/C in the second DS cycle gives about 1 % conversion of DBT.
  • the unfavorable thermodynamics for regenerating KH (or K) from K2S via the thermal treatment in H 2 at relatively low temperatures may cause the low conversion.
  • Table 5 lists desulfurization of DBT with reused KH/C.
  • the DS reactions use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under about 10 bar H 2 . with KH/C.
  • DS of DBT can be performed using KH/C and K/C in toluene-dg to provide the H/D exchange with the solvent under Ar atmosphere.
  • KH/C KH/C
  • K/C K/C
  • the distribution of the mass- to-charge ratios of biphenyl obtained in toluene-de may not differ from that in mesitylene.
  • FIG. 9 illustrates distribution of deuterated products of desulfurization of DBT on KH/C or K/C in toluene-ds in accordance with an embodiment of the invention.
  • the reaction conditions of 901 is at about 50 °C in Ar for about 7 hours.
  • the reaction conditions of 902 is at about 50 °C in Ar for about 20 hours.
  • the reaction conditions of 1003 is at about 165 °C in Ar for about 20 hours.
  • FIG. 10 illustrates distribution of deuterated products of hydrogenation of biphenyl in different conditions in accordance with an embodiment of the invention.
  • FIG. 10 illustrates a blank experiment (without KH/C) in toiuene-ds (1001 ), with KH/C in toluene-ds (1002 and 1003), and with KH/C in benzene-de (1004 and 1005).
  • the reaction conditions include molar ratio of K:DBT at about 2.3:1 , in Ar, at about 165 °C for about 20 hours.
  • 11 illustrates distribution of deuterated products of deoxygenation of dibenzofuran on KH/C in toluene-ds in accordance with an embodiment of the invention.
  • 1101 illustrates standard mass spectrometry of non-deuterated 2-pheny!phenoi.
  • 1102 illustrates mass spectrometry of deuterated 2-pbenyiphenol products (conversion of dibenzofuran is 100%; yield of 2-pheny!phenoi is 76%).
  • Reaction conditions include at about 165 °C in Ar for about 3 hours, using the molar ratio of K : DBF of about 2.3 : 1.
  • Several embodiments provide desulfurization activities on various potassium based materials including (but not limited to) KH/C, K/C, and methane pretreated K/C. Many embodiments provide that DS of DBT can occur in an inert gas including (but not limited to) argon, nitrogen, and helium, in hydrogen gas, or in methane gas.
  • K/C can be pretreated in methane. Methane pretreated K/C can remove almost 100% DBT at low temperature including (but not limited to) about 30 °C. At low temperatures, methane pretreated K/C may have better DS activity than K/C, and K/C may have better DS activity than KH/C. Some embodiments provide that methane pretreatment temperature may affect DS activity. Table 6 lists DS of DBT with different potassium based materials. The reaction conditions include mesitylene as a solvent, under about 10 bar of Ar or CH4, for about 20 hours.
  • KHMDS can cleave C-S bonds in heteroaromatic compounds and remove S.
  • FIG. 12 illustrates DS of DBT with KHMDS in accordance with an embodiment of the invention.
  • DBT 1201 can be reduced and form biphenyl 1202 and phenyl cyclohexane 1203 at different selectivity and/or yields under various reaction conditions,
  • Table 7 lists various reaction conditions of DBT with KHMDS.
  • DS of DBT with the KHMDS and Ha system may be more efficient in aliphatic n ⁇ octane relative to the tested aromatic solvents (Table 7, entries 3, 8, 9, 10).
  • sulfur removal may be stochiometric on KHMDS, but the utilization of potassium for DS can be high.
  • only a minor molar excess of KHMDS may be required for the complete conversion of DBT.
  • the efficiency of the KHMDS and H 2 system can be comparable to that of the KH/C systems.
  • the product selectivity may differ.
  • the overhydrogenation of the aromatic ring may not be observed using KHMDS and H 2 systems.
  • the yield of biphenyl may increase at a higher hydrogen pressure (Table 7, entries 3, 5, 7).
  • alkylated DBTs include (but are not Simited to) 4-methyldibenzothiophene (4-MeDBT), 4,6-dimethyldibenzothiophene (4,6- MeaDBT), and 4,6-diethyldibenzothiophene (4,6-Ei2DBT).
  • KH/C desulfurization of sulfur-containing compounds on KH/C including (but not limited to) dibenzothiophene suifone, diphenyl sulfide, 2-phenyithiophenol, polyphenylene sulfide, and di ⁇ /? ⁇ octyl sulfide.
  • KH/C is able to achieve ultra-deep desulfurization.
  • KH/C can reduce sulfur content of dibenzothiophene and dibenzothiophene derivatives to low ppm levels.
  • FIG. 13 illustrates a DS reaction scheme of alkylated DBTs in accordance with an embodiment of the invention.
  • Alkylated DBT 1301 can have different groups in R 1 and R 2 positions.
  • R 1 can be a hydrogen, a methyl, or a diethyl group.
  • R 2 can be a hydrogen, a methyl, or a diethyl group.
  • the DS process can produce biaryls 1302 and phenyl cyclohexane 1303.
  • Alkylated DBT desulfurization conditions can include, mesitylene as a solvent, reaction temperature of about 165 °C, reaction time from about 6 hour to about 20 hours, under about 10 bar Ar or about 10 bar Hs, with KH/C.
  • the DS process can use about 1.15 equivalent of KH/C per C-S bond.
  • Table 8 lists reaction conditions and product yields of desulfurization of various alkylated DBTs.
  • Table 8 lists conversion rate of alkylated DBT, the yield of biaryls, and the yield of phenyl cyclohexane under different conditions.
  • the yield of biaryls can be from about 91 % to about 95% after about 6 hours at about 185 °C under Ar. Yields from about 82% to about 90% of biaryls can be obtained when decreasing the reaction temperature to about 130 °C.
  • Desulfurization of 4-MeDBT may yield about 23% biaryl due to the hydrogenation of the unsubstituted phenyl ring, when Ar atmosphere is replaced by H 2 (Table 8, entry 4).
  • Biary! may not be formed during DS of 4,6-Me2DBT and 4,6-Et2DBT, showing that alkyl-substituted phenyl rings may not hydrogenated using KH/C in those conditions (Table 8, entries 5-6).
  • FIG. 14 illustrates a desulfurization reaction scheme of aliphatic d ⁇ -n- octyi sulfide in accordance with an embodiment.
  • the DS reactions may use cyclohexane as a solvent, reaction temperature at about 165 °C, reaction time of about 3 hours, under Ar, with KH/C at 1 .15 equivalent per C-S bond.
  • the desulfurization with KH/C can achieve about 92% yield at a full conversion of aliphatic di-n-octyl sulfide, when the reaction is performed in cyclohexane at about 165 °C for about 3 hours in Ar.
  • dia!ky!su!fides including (but not limited to) aliphatic di-n-octyl sulfide, may be challenging substrates for the DS with sodium.
  • FIG. 15 illustrates a desulfurization scheme of 4,6- Me 2 DBT and aliphatic di-n-octy! sulfide in accordance with an embodiment of the invention.
  • Table 9 lists desulfurization of 4,8-Me 2 DBT and aliphatic di-n-octyl sulfide with different molar ratios and in different solvents.
  • a chemose!ective DS of 4,6-Me 2 DBT may occur when an equimolar mixture of 4,6-Me 2 DBT and aliphatic di-n-octyl sulfide is treated with KH/C in mesityiene (Table 9, entry3). Certain embodiments provide that when this reaction is conducted in cyclohexane, both 4,6- MezDBT and aliphatic di-n-octyl sulfide may undergo desulfurization (Table 9, entry 4).
  • FIG. 16 illustrates a desulfurization reaction scheme of dibenzothiophene sulfone in accordance with an embodiment of the invention.
  • the DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 6 hours, under Ar, with KH/C at 3 equivalent per C-S bond, KH/C can provide desulfurization of dibenzothiophene sulfone with a yield of about 86% biphenyl at about 165 °C after about 6 hours under Ar in mesitylene, at 93% conversion of dibenzothiophene sulfone,
  • FIG. 17 illustrates a desulfurization reaction scheme of diphenyl sulfide in accordance with an embodiment.
  • the DS reactions may use mesityiene as a solvent, reaction temperature at about 200 °C, reaction time of about 20 hours, under Hz, with KH/C at 1.15 equivalent per C-S bond.
  • the desulfurization reaction of diphenyl sulfide with KH/C in mesitylene, at about 200 °C, for about 20 hours, under Hz, may result in full conversion and about 61% yield of benzene.
  • Table 10 lists desulfurization of diphenyl sulfide using KH/C in mesityiene under different reaction conditions.
  • the DS reactions use mesitylene as a solvent, reaction temperature from about 130 °C to about 200 °C, reaction time of about 20 hours, under about 10 bar Ar or Hz, with KH/C at 1 .15 equivalent per C-S bond.
  • Yield of benzene may decrease to about 40% and about 18% when reaction is performed at about 165 °C and about 130 °C, respectively (Table 10, entries 2 and 4). Conversion of diphenyl sulfide and yield of benzene may be consistently lower when Ar is used in place of Hz, disregard of the reaction temperature (130, 165 or 200 °C, Table 10, entries 1 , 3 and 5).
  • FIG. 18 illustrates a desulfurization reaction of 2-phenyltbiophenol in accordance with an embodiment.
  • the DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under Fte, with KH/C at 1 .15 equivalent per C-S bond.
  • the reaction may take place at about 165 °C under H 2 , and lead to complete conversion of 2-phenylthiophenoi.
  • Some embodiments provide about 22% yield of phenyl cyclohexane may be obtained. The low yield may be due to the strong adsorption of potassium thiophenolate on KH/C.
  • Certain embodiments provide that stirring the reaction mixture with isopropanol may achieve a similar yield of phenyl cyclohexane.
  • FIG. 19 illustrates a desulfurization reaction of PPS in accordance with an embodiment of the invention.
  • FIG. 19 shows that PPS (1 ) can be desulfurized and generate benzene (2), cyclohexane (3), phenylcyclohexane (4), 1 ,3-dimethylbenzene (5), and a mixture of isomers of demetbyiated biphenyls (8).
  • Table 11 lists desulfurization of PPS on KH/C in different conditions.
  • the DS conditions may include 1.15 equivalent of KH/C per C-S bond.
  • DS of PPS is carried out in various solvents: mesitylene, toluene, and n-octane.
  • Some embodiments provide that DS activity of PPS on KH/C is higher in an aromatic solvent than in an aliphatic solvent.
  • DS activity of PPS on KH/C is higher in H 2 than those in Ar.
  • C-C coupling product phenylcyclohexane (4) may be observed when reaction performed in H 2 ; while production of biphenyl may not be observed.
  • Cyclohexane (3) may be formed only in mesitylene. 1 ,3- dimethylbenzene (5) can be formed due to the demethylation of mesitylene.
  • a mixture of isomers of demethylated biphenyls (6) may be formed in mesitylene due to coupling of the radicals of benzene and 1 ,3-dimethylbenzene, and its subsequent isomerization.
  • a mixture of isomers of demethy!ated biphenyls (6) may be formed in toluene due to coupling of toluene radicals and its subsequent isomerization.
  • KH/C can reduce sulfur content of dibenzothiophene and its derivatives to low ppm levels.
  • KH/C can reduce sulfur concentration of 4,6-Me2DBT to less than about 3 ppm.
  • the concentration of [S] due to 4,6-Mb2qBT in the mesitylene solution can be lowered from about 1000 - 100 ppm to [S] less than 3 ppm.
  • Table 12 lists [S] concentration in the solution before and after the ultra-deep desulfurization of 4,8-Me2-DBT.
  • the ultra-deep desulfurization in accordance with some embodiments can take place with about 3 molar equivalents of KH/C at about 185 °C for about 20 hours (Table 12, entries 1-2). With about 10 ppm of [S] in solution, the ppm content about 2.4 ppm of 4,6-Me2DBT can be achieved with 12 equivalent of KH/C (Table 12, entry 3).
  • Desulfurization of Dibenzothioohene Derivatives with Molecular Potassium Compounds Many embodiments provide desulfurization of dibenzothiophene derivatives including (but not limited to) alkylated dibenzothiphene using molecular potassium compounds including (but not limited to) KHMDS.
  • Alkylated DBTs include (but are not limited to) 4,6-dimethyldibenzothiophene (4,6 ⁇ Me 2 DBT), and 4,6- diethyidibenzothiophene (4,6-Et2DBT).
  • Many embodiments provide desulfurization reactivity of DBT derivatives on KHMDS: DBT > 4,6 ⁇ Me 2 DBT > 4,6 ⁇ Et 2 DBT.
  • the relatively lower DS activity on alkylated DBT may be due to the steric effect of substituted alkyl groups. Such steric effect may not be observed with the KH/C system, where the DS efficiency may not depend on the steric bulk of DBT derivatives.
  • FIG. 20 illustrates a DS reaction scheme of alkylated DBTs with KHMDS in accordance with an embodiment of the invention.
  • Alkylated DBT 2001 can have different groups in R 1 and R 2 positions.
  • R 1 can be a hydrogen, a methyl, or a diethyl group.
  • R 2 can be a hydrogen, a methyl, or a diethyl group.
  • the DS process can produce biaryls 2002 and phenyl cyclohexane 2003.
  • Table 13 lists desulfurization of alkylated DBT using KHIVIDS in hydrogen.
  • the reaction conditions include: KHIVIDS is about 1.15 equivalent per C-S bond, solution is n-octane, reaction temperature about 165 °C, reaction time about 20 hours, under hydrogen gas.
  • KH/C can be used for the reductive cleavage of C — O bonds.
  • KH/C can convert dibenzofuran to 2-phenylphenol by cleaving the C-0 bonds.
  • KH/C in accordance with several embodiments eliminates the use of transition metals and/or silane in deoxygenation processes. Deoxygenation processes with KH/C can undergo milder reaction conditions including (but not limited to) less amount of KH/C compared to other catalysts, lower reaction temperature and shorter reaction time.
  • FIG. 21 A and FIG. 21 B illustrate reaction schemes of dibenzofuran conversion with KH/C in accordance with an embodiment. In FIG.
  • dibenzofuran can be converted to 2-phenyiphenol by KH/C.
  • the reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 3 hours, under Ar, with KH/C at 1 .15 equivalent per C-0 bond.
  • FIG. 21 B illustrates that dibenzofuran can be converted to 2-phenyiphenol, 2-cyclohexyiphenol, and phenyl cyclohexane by KH/C.
  • Table 14 lists deoxygenation of dibenzofuran on KH/C under different conditions.
  • the reactions may use mesitylene as a solvent, at a temperature of about 165 °C.
  • reaction time from about 3 hours to about 8 hours, under about 10 bar Ar or H 2 , with KH/C at 1.15 equivalent per C-0 bond.
  • KH/C may convert dibenzofuran at about 165 °C for about 3 hours with a conversion rate of about 100% and 76% under Ar and H 2 , respectively (Table 14, entries 1-2), About 1 % yield of 2-phenylpbenoi can be detected in the supernatant after the reaction.
  • stirring the reaction mixture with isopropanol may increase 2-phenylphenoi yield to about 83%. This suggests a strong adsorption of potassium aryloxide of 2-phenyiphenol on the reacted KH/C and its protonation by isopropanol.
  • KH/C can be used for the reductive cleavage of C-N bonds.
  • Many embodiments provide denitrogenation of 9- phenyicarbazole with KH/C.
  • KH/C can eliminate the use of transition metals and/or silane in denitrogenation processes. Denitrogenation processes with KH/C can undergo milder reaction conditions including (but not limited to) less amount of KH/C compared to other catalysts, lower reaction temperature and shorter reaction time.
  • FIG. 22 illustrates a reaction scheme of denitrogenation of 9- phenylcarbazole in accordance with an embodiment of the invention.
  • the reactions may use mesity!ene as a solvent, reaction temperature at about 185 °C, reaction time of about 20 hours, under H 2 , with KH/C at 0.78 equivalent per C-N bond.
  • Table 15 lists denitrogenation of 9-phenylcarbazole with KH/C under different conditions.
  • 9- phenylcarbazoie with KH/C in mesityiene at about 185 °C under Ar provides benzene as the detected product at about 35% yield and at about 35% conversion of 9- phenylcarbazole (Table 15, entry 1 ).
  • performing this reaction under H 2 may increase conversion of 9-phenylcarbazole to about 49% and yield about 38% benzene, about 12% biphenyl, and about 8% phenylcyciohexane.
  • Increasing the ratio of KH/C: 9-pheny!carbazole from 2.3:1 to 3.3:1 may not increase yield of products (Table 15, entries 3-4).
  • Increasing H 2 pressure from 10 to 100 bar may lead to a higher conversion of 9-phenylcarbazole, from about 49% conversion to about 80%, and yield about 51% yield of benzene and about 18% of phenylcyclohexane (Table 15, entry 5).
  • Adding isopropanol to the reaction mixture of 9-phenylcarbazole may not lead to higher yields of products (Table 15, entry 6).
  • alkali metal supported by carbon including (but not limited to) K/C can initiate dehydrogenation processes.
  • carbon-supported alkali metal hydride including (but not limited to) KH/C may participate in dehydrogenation processes.
  • KH/C may act as a precursor and decompose to K/C at dehydrogenation temperatures of at least 400 °C.
  • K/C in accordance with some embodiments can activate C-H bonds and remove hydrogen.
  • Many embodiments provide dehydrogenation of propane with K/C and KH/C. K/C and KH/C may have similar reactivities during dehydrogenation of propane processes.
  • PDH Propane dehydrogenation
  • FIG. 23 illustrates main target reaction and side reactions of PDH.
  • Conventional PDH catalysts include K(Na)-Cr0x/Ai203 in the Catofin process, and K(Na)-Pt-Sn/Al203 in the Oleflex process.
  • K(Na)-Cr0x/Ai203 can be toxic and can be deactivated quickly.
  • K(Na)-Pt- Sn/AbGs can be high cost, and may have high tendency to sintering and to form coke.
  • K/C and KH/C can have high conversion rate of propane.
  • Propane (C 3 H 8 ) dehydrogenation with K/C can generate propylene (C 3 H 6 ), ethane (C 2 H 6 ), ethylene (C 2 H 4 ), and methane (CH4).
  • FIGs. 24A - 24D illustrate conversion and product yields during propane dehydrogenation on K/C at about 500 °C in accordance with an embodiment of the invention.
  • the reaction conditions of propane dehydrogenation reactions include 5% C3H8 in N2 with about 100 mg 30 wt.% K/C. Total flow rate is about 10 mi min '1 . Temperature is about 500 °C.
  • FIG. 24A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • CsHe selectivity firstly increases to about 75% in about 120 minutes and then decreases to about 43% after about 650 minutes.
  • FIG. 24B shows propylene production rate. Deactivation can be observed. Production rate of CaHe firstly increases to about 1.4 mmol g cat -1 h -1 and then decreases to about 0.1 mmol gcaf 1 h "1 along the reaction time.
  • FIG. 24C shows the conversion percentage of propane vs time
  • FIG. 24D shows the percentage of carbon balance.
  • FIGs. 25A - 25D illustrate conversion and product formation rates during propane dehydrogenation on K/C at about 400 °C in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% C3H3 in N2 with about 100 mg 30 wt.% K/C. Total flow rate is about 10 ml min 1 . Temperature is about 400 °C.
  • FIG. 25A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • CFU may be the main product.
  • CsHe selectivity increases rapidly from 9% to 91 % in 30 min and then keeps stable.
  • FIG. 24B shows propylene production rate. Production rate of CsHe gradually decreases from 0.3 to 0.1 mmol gcat "1 IT 1 along the reaction time.
  • FIG. 24C shows the conversion percentage of propane vs time.
  • FIG. 24D shows the percentage of carbon balance.
  • 20 wt.%KH/C and 30 wt.% KH/C may have similar selectivity during PDH with that on 30 wt.% K/C at about 400 °C.
  • K/C and KH/C may become amorphous after PDH processes.
  • CsHe production rate on KH/C may be higher than on K/C under same reaction conditions.
  • FIGs. 26A - 26D illustrate conversion and product yields during propane dehydrogenation on 30wt.% KH/C at about 400 °C in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% CsHs in N2 with about 100 mg 30 wt.% KH/C.
  • FIG. 26A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • CH4 may be the main product.
  • CsHs selectivity increases rapidly from 9% to 91 % in 30 min and then keeps stable, similar to K/C.
  • FIG. 28B shows propylene production rate. Deactivation may be observed. Production rate of CsHe firstly increases to about 0.5 mmol g cat -1 h -1 and then decreases to about 0.3 mmol g cat -1 h -1 after about 1300 min.
  • FIG. 26A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • CH4 may be the main product.
  • CsHs selectivity increases rapidly from 9% to 91 % in 30 min and then keeps stable, similar to K/C.
  • FIG. 26C shows the conversion percentage of propane vs time.
  • FIG. 28D shows the percentage of carbon balance.
  • CsHe production rate on 20 wt.% KH/C may be comparable to 30 wt.% KH/C under same reaction conditions.
  • FIGs. 27A - 27D illustrate conversion and product yields during propane dehydrogenation on 2Qwt.% KH/C at about 400 X in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% CsHs in Nb with about 100 mg 20 wt.% KH/C. Total flow rate is about 10 ml min '1 . Temperature is about 400 °C.
  • FIG. 27A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • CH4 may be the main product.
  • C3H6 selectivity increases rapidly to about 94%, similar to 30 wt% KH/C.
  • FIG. 27B shows propylene production rate. Production rate of C3H6 firstly increases to about 0.5 mmol g cat -1 h -1 and then decreases to about 0.1 mmol g cat -1 h -1 after about 2000 min.
  • FIG. 27C shows the conversion percentage of propane vs time.
  • FIG. 27D shows the percentage of carbon balance.
  • F!Gs. 28A - 28D illustrate conversion and product formation rates during propane dehydrogenation on 1Gwt.% KH/C at about 400 X in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% C3H8 in N2 with about 100 mg 10 wt.% KH/C. Total flow rate is about 10 ml min '1 . Temperature is about 400 X.
  • FIG. 28A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • FIG. 28B shows propylene production rate. Deactivation may be observed. C3H6 selectivity may keep at about 90% in 400 min, after which gradually decreases to about 84% in 700 min.
  • FIG. 28C shows the conversion percentage of propane vs time.
  • FIG. 28D shows the percentage of carbon balance.
  • FIGs. 29A - 29D illustrate conversion and product yields during propane dehydrogenation on carbon at about 400 °C in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% C3H6 in ISh with about 70 mg carbon.
  • FIG. 29A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond).
  • bare carbon support shows an initial CsHe selectivity of about 91%, which gradually decreases to about 68% after 600 min.
  • FIG. 29B shows propylene production rate. Production rate of C3H6 is slow at about 0.01 mmol g cat -1 h -1 .
  • FIG. 29C shows the conversion percentage of propane vs time.
  • FIG. 29D shows the percentage of carbon balance.
  • FIGs. 30A - 30D illustrate conversion and product formation rates during propane dehydrogenation on carbon at about 500 °C in accordance with an embodiment of the invention.
  • the reaction conditions of PDH include 5% CaHs in N2 with about 70 mg carbon. Total flow rate is about 10 mi min -1 . Temperature is about 500 °C.
  • FIG. 30A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At 500 °C, bare carbon support shows lower selectivity (ca. 50%) to C3H6. Cracking of C3He to CH4 and C2H4 may be the main side reaction, which can compete with PDH.
  • FIG. 30B shows propylene production rate.
  • FIG. 30C shows the conversion percentage of propane vs time.
  • FIG. 30D shows the percentage of carbon balance.
  • KH/C can participate in catalytic hydrogenation processes and provide hydrogen to compounds including (but not limited to) aikynes and unsubstituted phenyl rings.
  • KH/C can cleave C-C bonds during hydrogenation processes.
  • KH/C can convert aikynes to olefins with high selectivity, that is, without forming large amounts of alkanes.
  • KH/C can catalyze hydrogenation of unsubstituted phenyl rings including (but not limited to) biphenyl.
  • phenyicyclohexane can be a secondary product formed via hydrogenation of biphenyl.
  • Several embodiments provide that the subsequent hydrogenation of phenyicyclohexane to bicyclohexane on KH/C can proceed under a higher pressure of hydrogen,
  • FIG. 31 illustrates a reaction scheme of hydrogenation of biphenyl to phenyicyclohexane in accordance with an embodiment of the invention.
  • the hydrogenation of biphenyl to phenyicyclohexane on the KH/C is catalytic with turnover numbers (TON) of up to 23.
  • TON turnover numbers
  • phenyicyclohexane may be a hydrogenation product independent on the stoichiometric ratios of biphenyl to KH used.
  • phenyicyclohexane may not form on a bare carbon support. With the absence of H 2 and using about 2,3:1 molar ratio of KH/C to biphenyl, about 3% yield of phenyicyclohexane can be obtained.
  • FIG. 32 illustrates a reaction scheme of hydrogenation of phenylcyclohexane to bicyclohexane in accordance with an embodiment of the invention.
  • the yield of bicyclohexane may be about 3%, likely because of the steric effect of the cydohexyi group in phenylcyclohexane.
  • Table 17 lists hydrogenation of phenylcyclohexane using KH/C.
  • the catalytic hydrogenation reactions use mesitylene as a solvent, reaction temperature from about 165 °C to about 200 °C, reaction time of about 20 hours, under about 10 bar or about 100 bar H 2 , with KH/C.
  • the ratio of KH/C is about 0.37 equivalent per C-H bond.
  • Turnover number (TON) is calculated based on the mol of hydrogenated C ⁇ C bonds per mol of KH in KH/C,
  • FIG. 33 illustrates a hydrogenation scheme of phenyiacetylene in accordance with an embodiment of the invention, FIG. 33 shows that the target semihydrogenation product styrene can be a major product of phenyiacetylene hydrogenation. Carbon coupling products including dimers and trimers may also form.
  • Table 18 lists various reaction conditions of phenyiacetylene hydrogenation reactions.
  • the solvent used in all reactions is mesityiene.
  • the molar ratio between KH and phenyiacetylene is about 1 :10.
  • the selectivity of styrene can be up to about 86% (at about 33% conversion of phenyiacetylene, Table 6 entry 1 ).
  • KH/C can be prepared by heating at about 110 °C metallic potassium mixed with a carbon support (graphite, surface area about 500 m 2 g ⁇ 1 ) under about 10 bar of H 2 for about 10 hours.
  • the loading of K on KH/C is about 30.1 wt% according to inductively coupled plasma optical emission spectroscopy (ICP-OES), which is close to the nominal loading of 30 wt%.
  • ICP-OES inductively coupled plasma optical emission spectroscopy
  • the content of various transition metals (Co, Fe, Cu, Ni, Mo, V, Mn, Cr, Cd, In, Ag, Pd, Pb, Pt, Ru, and Zn) in KH/C is below the detection limit (less than about 1 ppm) of the ICP-OES.
  • X-ray diffraction (XRD) pattern of KH/C contains peaks attributed to graphite (at about 28°, 43° and 54°) and to potassium hydride (at about 27°, 31°, 45°, 53° and 56°), consistent with the oxidation of metallic K by H 2 .
  • the crystallite size of KH in KH/C is about 40 nm.
  • Temperature-programmed desorption (TPD) can be performed to quantify the amount of KH in KH/C. Three peaks corresponding to the release of H 2 , at about 171 , 327 and 400 °C, can be observed.
  • the quantity of H 2 released from KH/C during the TPD experiment under an Ar flow is about 4.5 mmol H 2 g KH/c ⁇ -1 which is higher than the quantity of H 2 expected from the KH loading by ICP-OES (3.8 mmol H 2 g KH/c -1 ). This suggests that KH/C contains additional chemisorbed H 2 .
  • a reference K/C material can be prepared as described above for KH/C except that an Ar atmosphere is used instead of H 2 . This K/C material has a K loading of about 28.9 wt% according to ICP-OES, and is amorphous by XRD.
  • KH/C can be prepared by a melt impregnation method.
  • the carbon support (graphene nanoplateiets with a BET surface area of ca. 500 m 2 g ”1 ) can be pre-treated in a N2 flow (30 ml min -1 ) at about 550 °C for about 6 hours and then stored in a Na-filled glovebox.
  • about 150 mg of metallic potassium and about 350 mg of the pre-treated carbon support can be physically mixed and placed into an autoclave with a glass liner. Then the autoclave may be sealed, brought out from the glovebox and connected to a high pressure H 2 line.
  • the line can be purged (5 times with 10 bar of H 2 ), the autoclave pressurized to about 10 bar of H 2 , heated to about 110 °C (ramping rate at 5 °C min -1 ) and hold at this temperature for about 10 hours.
  • the solid material in the autoclave can be collected under the glovebox atmosphere and carefully mixed by using mortar and pestle.
  • the K/C material can be prepared in the same manner as KH/C except that the autoclave is pressurized with 10 bar of Ar instead of H 2 .
  • a postdecomposition sample of KH/C can be prepared by treating about 150 mg of fresh KH/C in 10 ml of mesitylene in an autoclave under 10 bar Ar (165 °C, 20 hours). After this time, the material may be dried under vacuum on a Scbienk line at room temperature and handled without exposure to air.
  • Example 2 Desulfurization of dibenzothiophene and its derivatives
  • a known amount of a solid material KH/C, K/C, commercial KH or KHMDS, typically 12-92 mg, 0.09-0.71 mmol K
  • a known volume of about 0.03 M mesitylene solution of a substrate typically, 5-10 ml, 0.15-0.30 mmol
  • the autoclave can be sealed, brought out from the glovebox and connected to a high pressure line of Ar or H 2 .
  • the line can be purged (5 times with 10 bar of Ar or H 2 ) and the autoclave can be pressurized to a set pressure of Ar or H 2 and heated to desired temperature (ramping rate at 5 °C min -1 ) with mechanical stirring at about 500 rpm.
  • the reaction mixture can open in air, filtered (filter paper) and the supernatant collected and analyzed by GC-MS.
  • Example 3 Desulfurization of 2-phenylthiophenol [00117] Some embodiments provide desulfurization of 2-phenylthiopheno! on KH/C.
  • the desulfurization can be performed following the same procedure for DS of dibenzothiophene in Example 2.
  • the reaction mixture can be treated in two ways: 1 ) the reaction mixture can be filtered through a filter paper and the supernatant analyzed by GC-MS, or 2) 0.3 ml of isopropanol can be added to the reaction mixture at room temperature and stirred for about 3 hours. Then this reaction mixture filtered through a filter paper and the supernatant analyzed by GC-MS.
  • Example 4 Desulfurization of di-n-octyl sulfide and diphenyl sulfide [00118] Many embodiments provide desulfurization of di-n-octyl sulfide and diphenyl sulfide on KH/C. KH/C (48 mg, 0.35 mmol K) and 5 ml of solvent (cyclohexane or mesityiene) can be added to a glass liner in a Nfe-fil!ed glovebox.
  • KH/C 48 mg, 0.35 mmol K
  • solvent cyclohexane or mesityiene
  • the autoclave can be brought out from the glovebox, 45 pi (0,15 mmol) of di-/?-octyl sulfide or 25 pi (0,15 mmol) of diphenyl sulfide can be quickly injected to the liner and the autoclave sealed immediately.
  • the autoclave can be then filled with Ar or H 2 and experiments run as described above for the desulfurization of dibenzothiophene.
  • Example 5 Desulfurization of dihenzothiophene-sulfone and polyphenylene sulfide [00119]
  • Several embodiments provide desulfurization procedures of dibenzothiophene- sulfone and polyphenylene sulfide KH/C.
  • KH/C typically, 46-118 mg, 0.35-0.91 mmol K
  • the solid substrate and 5 ml mesityiene, toluene or n ⁇ octane can be added to a glass liner in the glovebox.
  • the molar ratio of KH to sulfur in the reaction mixture may range from 2.3:1 to 6:1. Experiments run as described in Example 2 for desulfurization of dibenzothiophene.
  • the reaction mixture can be opened in air, filtered (filter paper) and the supernatant collected and analyzed by GC-MS. Conversion of dibenzothiophene sulfone can be determined by 1 H NMR spectroscopy.
  • the reaction mixture after DS of dibenzothiophene-sulfone can be filtered through a filter paper and the supernatant can be collected.
  • the supernatant can be dried under vacuum using a Schienk line at room temperature.
  • precipitate can be dissolved in 400 pL CDCIs (containing 0.01 M 1 ,3,5-trimethoxybenzene as an internal standard).
  • the CDCta solution can be used for NMR measurement.
  • Solutions of 4,6-DMDBT in mesitylene with a concentration of 1000 ppm (a), 100 ppm (b) or 10 ppm (c) can be prepared in a Ns-filled glovebox.
  • Solution (a) can be prepared by dissolving 284 mg (1 .25 mmol) of 4,8-DMDBT in 46 ml mesitylene.
  • Solutions (b) and (c) can be prepared, respectively, by a 10-fold and a 100-fold dilution of solution a with mesitylene.
  • a known amount of KH/C and a known volume of 4,8-DMDBT solution (a, b, or c) can be added to a glass liner of the autoclave. More specifically, 9-218 mg of KH/C (0.07-1.86 mmol K) can be mixed with 20 mi of the substrate solution to reach about 3:1 or 12:1 molar ratio of KH : 4,6-DMDBT.
  • the autoclave can be sealed, brought out from the glovebox and connected to a high pressure Ar line. The line can be purged and the autoclave can be pressurized to 10 bar of Ar. Desulfurization experiments can run at 185 °C for 20 h under mechanical stirring (500 rpm). After this time, the autoclave can be depressurized and the reaction mixture filtered three times to remove the solid material (filter paper). The supernatant can be collected and used to determine the quantity of sulfur and potassium after the reaction by iCP- OES.
  • Deuteration experiments can be conducted by using toiuene-ds or benzene-de as the solvent in accordance with some embodiments.
  • the experimental procedure is similar as the desulfurization of dibenzothiophene or deoxygenation of dibenzofuran.
  • KH/C 28 mg, 0.21 mmol KH
  • DBT 18.6 mg, 0.09 mmol
  • biphenyl (13.9 mg, 0.09 mmol
  • dibenzofuran 15,1 mg, 0.09 mmol
  • the reactions can be performed at 50 or 185 °C in 10 bar of Ar for 3-20 h. Identification of products and their mass number analyses can be performed using the gas chromatography mass spectrometer (GC-MS).
  • the performance of propane dehydrogenation on KH/C, K/C or bare carbon support can be evaluated using a fixed bed reactor.
  • 100 mg of solid material can be loaded between two plugs of quartz wool into a fixed-bed reactor in a ISb-fvetted glovebox.
  • the reactor can be sealed, brought out from the glovebox and connected to a gas line.
  • the gas line can be purged by a flow of N2 and then a mixture of 5% C3H3 in N2 (total flow rate of 10 ml min -1 ) can be flown Into the reactor.
  • the reactor can be heated to the desired reaction temperature (400 or 500 °C, 10 °C min -1 ).
  • the off-gas composition can be analysed using a Clarus 480 gas chromatograph (PerkinEimer) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD).
  • the chromatograms can be acquired every 14 minutes.
  • the terms “substantially” and “about” are used to describe and account for small variations.
  • the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation.
  • the terms can refer to a range of variation of less than or equal to ⁇ 10% of that numerical value, such as less than or equal to ⁇ 5%, less than or equal to ⁇ 4%, less than or equal to ⁇ 3%, less than or equal to ⁇ 2%, less than or equal to ⁇ 1 %, less than or equal to ⁇ 0,5%, less than or equal to ⁇ 0.1 %, or less than or equal to ⁇ 0.05%.

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Abstract

Systems and methods for desulfurization, denitrogenation, deoxygenation, dehydrogenation and hydrogenation with materials containing alkali metals are described. The desulfurization, denitrogenation, deoxygenation, dehydrogenation, and hydrogenation processes are silane free and transition metal free. The alkali metal containing materials include alkali metal hydrides supported on carbon substrates and/or molecular compounds of alkali metals.

Description

SYSTEMS AND METHODS FOR DESULFURIZATION, DENITROGENATION, DEOXYGENATION, HYDROGENATION, AND DEHYDROGENATION WITH ALKALI
METAL CONTAINING MATERIALS
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The current application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/193,846 entitled “Systems and Methods for Hydrodesulfurization” filed May 27, 2021 , and U.S. Provisional Patent Application No. 63/363,610 entitled “Carbon-Supported Potassium Hydride for Efficient Low-Temperature Desulfurization” filed April 26, 2022. The disclosures of U.S. Provisional Patent Application Nos. 63/193,846 and 63/363,610 are hereby incorporated by reference in their entirety for all purposes.
FIELD OF THE INVENTION
[0002] The present invention generally relates to systems and methods for desulfurization, denitrogenation, deoxygenation, hydrogenation, and dehydrogenation with alkali metal containing materials; and more particularly to silane-free and transition metal free systems and methods for reductive cleavage of C-S, C-N, C-O, C-C, and C-H bonds with carbon-supported alkali metal hydrides, carbon-supported alkali metal, and/or molecular compunds of alkali metals.
BACKGROUND OF THE INVENTION
[0003] Desulfurization (DS) and hydrodesuifurization (HDS) are processes by which sulfur-containing impurities can be removed from petroleum streams, for example using a heterogeneous, sulfided transition metal catalyst under high Hs pressures and temperatures (typical for HDS). Although generally effective, a major obstacle that remains is the desulfurization of highly refractory sulfur (S) - containing heterocycles that are naturally occurring in fossil fuels. Homogeneous hydrodesuifurization strategies using well-defined molecular catalysts have been designed to target these recalcitrant S - heterocycles. However, the formation of stable transition metal sulfide complexes following C-S bond activation has prevented catalytic turnover, and lack of affordable reactants and reaction conditions have hindered wide applications.
[0004] Denitrogenation (DM) and hydrodenitrogenation (HDN) are processes for the removal of nitrogen from petroleum streams. The hydrodenitrogenation process in a refinery removes nitrogen from the feedstocks, which often occurs concurrently with removal of sulfur from the feedstock. Organonitrogen compounds, even though they may occur at low levels, are undesirable because they cause poisoning of downstream catalysts. Furthermore, upon combustion, organonitrogen compounds generate NOx, a pollutant. Typical catalysts for the denitrogenation of petroleum streams can include molybdenum disulfide or tungsten disulfide supported on alumina promoted by cobalt or nickel.
[0005] Deoxygenation (DO) and hydrodeoxygenation (HDO) are processes for removing oxygen from oxygen-containing compounds. Deoxygenation can be a promising technology to remove the oxygen from biomass-derived streams, for example obtained after pyrolysis. One obstacle is to find selective catalysts to minimize the use of hydrogen while maintaining the aromatic functionality of lignin. Typical catalysts for the deoxygenation of petroleum streams can include molybdenum disulfide or tungsten disulfide supported on alumina promoted by cobalt or nickel.
[0006] Dehydrogenation (DH) is a process by which hydrogen is removed from an organic compound to form a new chemical (e.g., to convert saturated compounds into unsaturated compounds). It is the reverse process of hydrogenation. It can be used to produce alkenes by the dehydrogenation of alkanes. Dehydrogenation products may include ethene, propene, and styrene. It is a challenging reaction as the fouling and deactivation of many catalysts may take place, in particular via coking, which is the dehydrogenative polymerization of organic substrates. BRIEF SUMMARY OF THE INVENTION
[0007] Many embodiments are directed to systems and methods for desulfurization with carbon-supported alkali metal hydrides and/or molecular compounds of alkali metals. Several embodiments provide catalytic hydrogenation capabilities with carbon-supported alkali metal hydrides. In some embodiments, carbon-supported alkali metal hydrides can participate in denitrogenation, deoxygenation, and dehydrogenation processes. A number of embodiments provide that carbon-supported alkali metal hydrides and carbon- supported alkali metal may have similar reactivities during dehydrogenation processes for propane.
[0008] An embodiment of the invention includes a system for desulfurization, denitrogenation, deoxygenaiion, dehydrogenation, and hydrogenation comprising at least one alkali metal hydride of a formula MaHb, and a carbon substrate. M is selected from the group consisting of lithium, sodium, and potassium, and a molar ratio a/b between M and H is: G < a/b < 1 ; the at least one alkali metal hydride is supported on the carbon substrate; and the system reductiveiy cleaves at least one C-X bond in an organic substrate, where X is selected from the group consisting of S, N, O, H, and C.
[0009] In another embodiment, the system is free of transition metal and free of silane. [0010] In a further embodiment, the system reductiveiy cleaves at least one C-S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound. [0011] In an additional embodiment, the system reductiveiy cleaves at least one C-S bond in a S-containing organic substrate selected from the group consisting of dibenzothiopbene, 4,6-dimethyidibenzothiophene, 4,6-diethyldibenzothiophene, 4- methyidibenzothiophene, dibenzothiopbene suifone, diphenyl sulfide, 2- phenyithiophenol, polyphenylene sulfide, and aliphatic di-n-octyi sulfide.
[0012] In another further embodiment, the desulfurization occurs at a temperature between 50 °C and 165 °C.
[0013] In another embodiment again, the system reductiveiy cleaves at least one C-N bond in a N-containing heterocyclic compound.
[0014] In yet another embodiment, the N-containing heterocyclic compound is 9- phenyl-carbazole. [0015] In another yet embodiment, the system reductively cleaves at least one C-0 bond in a G-coniaining heterocyclic compound.
[0016] in a yet further embodiment, wherein the O-containing heterocyclic compound is dibenzofuran.
[0017] In yet another embodiment again, the system reductively cleaves at least one C-H bond and removes at least one H in propane.
[0018] In a yet further embodiment, the alkali metal is potassium and potassium hydride on carbon decomposes to potassium on carbon during propane dehydrogenation. [0019] In a further additional embodiment, the potassium hydride on carbon has a weight percentage between 20% and 30%.
[0020] In another further embodiment, the at least one alkali metal hydride is potassium hydride and the carbon substrate is graphite.
[0021] A further embodiment again further comprises an organic solvent.
[0022] In yet another embodiment, the organic solvent is selected from the group consisting of mesityiene, cyclohexane, toluene, and /?-octane.
[0023] In a further yet embodiment again, the desulfurization, denitrogenation, and deoxygenation occur under hydrogen gas or an inert gas selected from the group consisting of argon, nitrogen, and helium.
[0024] In another yet embodiment, the dehydrogenation occurs under an inert gas selected from the group consisting of argon, nitrogen, and helium.
[0025] in an additional further embodiment, the system cleaves at least one C-C bond in aromatic heterocyclic compounds and catalyticaily hydrogenizes at least one unsubstituted phenyl ring.
[0026] In yet another embodiment again, the unsubstituted phenyl ring is biphenyl. [0027] In a further additional embodiment, the system cleaves at least one C-C bond and catalyticaily hydrogenates at least one carbon triple bond in an aikyne to form at least one carbon double bond in an olefin.
[0028] In a further yet embodiment, the aikyne is pbenyiacety!ene,
[0029] In yet another further embodiment, the hydrogenation occurs under hydrogen gas. [0030] Another embodiment includes a system for dehydrogenation comprising at least one alkali metal, and a carbon substrate. The at least one alkali metal is selected from the group consisting of lithium, sodium, and potassium; the carbon substrate supports the at least one alkali metal; and the system reductively cleaves at least one C- X bond in an organic substrate, where X is H or C.
[0031] In an additional further embodiment, the organic substrate is propane.
[0032] In a further yet embodiment, a dehydrogenation temperature is at least 400 °C. [0033] In yet another embodiment again, the dehydrogenation occurs under an inert gas selected from the group consisting of nitrogen, helium, and argon.
[0034] In a yet further embodiment, the alkali metal is potassium and the carbon substrate is graphite.
[0035] In another further embodiment, the potassium on the carbon substrate has a weight percentage between 20% and 30%,
[0036] A further embodiment includes a system for desulfurization comprising a molecular compound comprising at least one alkali metal selected from the group consisting of lithium, sodium, and potassium.
[0037] In a further yet embodiment again, the system reductively cleaves at least one C-S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound.
[0038] In an additional embodiment again, the molecular compound is potassium bis(trimethylsilyl)amide.
[0039] In a yet another embodiment, the system if free of silane and free of transition metal.
[0040] A further yet embodiment comprises an organic solvent, wherein the organic solvent is selected from the group consisting of mesitylene, toluene, and n - octane.
[0041] In another embodiment again, the system reductively cleaves at least one C-S bond in a S-containing organic substrate selected from the group consisting of dibenzothiophene, 4,6-dimethyldibenzothiophene, and 4,6-diethyldibenzothiophene. [0042] Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosure, A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0001] The description will be more fully understood with reference to the following figures, which are presented as exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention, wherein:
[0002] FIG. 1 illustrates an industrial DS process with ColVloSx/AhCb as catalyst in accordance with prior art.
[0003] FIG. 2 illustrates chemical structures of DBT and DBT derivatives.
[0004] FIG. 3 illustrates the reaction scheme of desulfurization of DBT derivatives using KOSi reaction in accordance with prior art.
[0005] FIG. 4 illustrates the reaction scheme of KH partial desulfurization reaction in accordance with prior art.
[0006] FIG. 5 illustrates a reaction scheme of desulfurization of DBT derivatives with carbon-supported potassium hydride in accordance with an embodiment of the invention. [0007] FIG. 6 illustrates desulfurization of DBT in accordance with an embodiment of the invention.
[0008] FIGs. 7 A - 7D illustrate DS reactions under different conditions in accordance with an embodiment of the invention,
[0009] FIG. 8 illustrates XRD of KH/C collected after the desulfurization of dibenzothiophene in mesitylene in accordance with an embodiment of the invention. [0010] FIG. 9 illustrates distribution of deuterated products of desulfurization of DBT on KH/C or K/C in to!uene-ds in accordance with an embodiment of the invention,
[0011] FIG. 10 illustrates distribution of deuterated products of hydrogenation of biphenyl in different conditions in accordance with an embodiment of the invention. [0012] FIG. 11 illustrates distribution of deuterated products of deoxygenation of dibenzofuran on KH/C in toluene-da in accordance with an embodiment of the invention. [0013] FIG. 12 illustrates desulfurization of DBT with KHMDS in accordance with an embodiment of the invention.
[0014] FIG. 13 illustrates a DS reaction scheme of DBT derivatives, including alkylated DBTs, in accordance with an embodiment of the invention.
[0015] FIG. 14 illustrates a desulfurization reaction scheme of aliphatic di-n-octyl sulfide in accordance with an embodiment.
[0016] FIG. 15 illustrates a desulfurization scheme of 4,6-Me2DBT and aliphatic di ~n~ octyl sulfide in accordance with an embodiment of the invention,
[0017] FIG. 16 illustrates a desulfurization reaction scheme of dibenzothiophene su!fone in accordance with an embodiment of the invention,
[0018] FIG. 17 illustrates a desulfurization reaction scheme of diphenyl sulfide in accordance with an embodiment.
[0019] FIG. 18 illustrates a desulfurization reaction of 2-phenylthiophenol in accordance with an embodiment.
[0020] FIG. 19 illustrates a desulfurization reaction of polyphenylene sulfide in accordance with an embodiment of the invention.
[0021] FIG. 20 illustrates desulfurization of alkylated DBT with KH!VIDS in accordance with an embodiment of the invention.
[0022] FIGs, 21 A - 21 B illustrate reaction schemes of DO of dibenzofuran with KH/C in accordance with an embodiment.
[0023] FIG. 22 illustrates a reaction scheme of denitrogenation of 9-pheny!carbazole in accordance with an embodiment of the invention.
[0024] FIG. 23 illustrates main target reaction and side reactions of PDF! in accordance with prior art.
[0025] FIGs. 24A - 24D illustrate conversion and product formation rates during propane dehydrogenation on KIC at about 500 °C in accordance with an embodiment of the invention.
[0026] FIGs, 25A - 25D illustrate conversion and product yields during propane dehydrogenation on K/C at about 400 °C in accordance with an embodiment of the invention. [0027] FIGs, 28A - 28D illustrate conversion and product yields during propane dehydrogenation on 3Gwt.% KH/C at about 400 °C in accordance with an embodiment of the invention,
[0028] FIGs. 27A - 27D illustrate conversion and product yields during propane dehydrogenation on 20wt.% KH/C at about 400 °C in accordance with an embodiment of the invention.
[0029] FIGs. 28A - 28D illustrate conversion and product yields during propane dehydrogenation on 10wt% KH/C at about 400 °C in accordance with an embodiment of the invention.
[0030] FIGs, 29A - 29D illustrate conversion and product yields during propane dehydrogenation on carbon at about 400 °C in accordance with an embodiment of the invention.
[0031] FIGs. 30A - 30D illustrate conversion and product yields during propane dehydrogenation on carbon at about 500 °C in accordance with an embodiment of the invention.
[0032] FIG. 31 illustrates a reaction scheme of hydrogenation of biphenyl to phenylcyclohexane in accordance with an embodiment of the invention.
[0033] FIG. 32 illustrates a reaction scheme of hydrogenation of phenylcyclohexane to bicyclohexane in accordance with an embodiment of the invention.
[0034] FIG. 33 illustrates a reaction scheme of hydrogenation of alkyne to alkene in accordance with an embodiment of the invention,
DETAILED DESCRIPTION OF THE INVENTION
[0043] Turning now to the drawings and data, systems and methods of desulfurization (DS), denitrogenation (DN), deoxygenation (DO), dehydrogenation (DH), and catalytic hydrogenation with alkali metal containing materials are described. Many embodiments provide DS processes with alkali metal hydrides systems and/or molecular compounds of alkali metals. Some embodiments provide DN, DO, DH, and hydrogenation processes with alkali metal hydrides systems. Several embodiments provide that the DS, DN, DO, DH, and catalytic hydrogenation processes are free of transition metals and are free of silane. Some embodiments provide alkali metal hydrides can reductive!y cleave C-8, C~ N, C-O, C-C, and/or C-H bonds. Several embodiments provide that molecular compounds containing alkali metals can reductive!y cleave C-S bonds. A number of embodiments provide that alkali metal hydrides can initiate catalytic hydrogenation processes. Many embodiments provide alkali metal systems can participate in DH processes. Several embodiments provide alkali metal hydride including (but not limited to) potassium hydride (KH), sodium hydride (NaH), and lithium hydride (LiH) in the DS, DM, DO, DH, and catalytic hydrogenation processes. As can readily be appreciated, any of a variety of alkali metal hydride can be utilized as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. A number of embodiments provide alkali metal and/or alkali metal hydride can be supported on carbon-based substrate as the reactant. Some embodiments provide that metallic alkali metal can be mixed with a carbon-supported substrate including (but not limited to) graphite to form alkali metal on carbon (M/C). In certain embodiments, metallic alkali metal can be mixed with a carbon-based substrate including (but not limited to) graphite substrate in the presence of hydrogen to form alkali metal hydride (MH) on carbon (MH/C). As can readily be appreciated, any of a variety of carbon substrate can be utilized as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. Several embodiments provide that alkali metal-containing molecular compounds including (but not limited to) potassium bis(trimethyisilyi)amide (KHMDS) can be used to replace silane in DS reactions. As can readily be appreciated, any of a variety of alkali metai molecular compound can be utilized as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
[0044] Many embodiments use alkali metal hydrides and/or molecular compounds of alkali metals to remove sulfur-containing impurities during desulfurization processes. Several embodiments provide cleavage of C-S bonds in various organosulfur substrates under mild conditions including (but not limited to) lower reaction temperatures and shorter reaction time. Examples of sulfur-containing impurities include (but are not limited to) sulfur-containing heterocycies and sulfur-containing aliphatic compounds. Examples of sulfur-containing heterocycies include (but are not limited to): dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,8~IVIe2DBT), 4,6-dietby!dibenzothiophene (4,6-Et2DBT). 4-metbyldibenzothiophene (4-MeDBT), dibenzothiophene sulfone (DBT-SO2), diphenyl sulfide, 2-phenylthiophenol, and polyphenylene sulfide. Examples of sulfur-containing aliphatic compounds include (but are not limited to) aliphatic di-n-octy! sulfide. As can readily be appreciated, any of a variety of sulfur containing compound can be utilized during desulfurization process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. In many embodiments, alkali metal hydrides including (but not limited to) carbon-supported KH (KH/C) can participate in denitrogenation processes by cleaving C-N bonds and remove nitrogen from nitrogen- containing heteroaromatics including (but not limited to) 9-phenyl-carbazole. As can readily be appreciated, any of a variety of nitrogen containing compound can be utilized during denitrogenation process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. Several embodiments provide deoxygenation of oxygen-containing heteroaromatic compounds including (but not limited to) dibenzofuran with KH/C. KH/C can cleave C-0 bonds in heteroaromatic compounds in accordance with some embodiments. As can readily be appreciated, any of a variety of oxygen containing compound can be utilized during deoxygenation process as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
[0045] Many embodiments provide that carbon-supported alkali metal including (but not limited to) K/C and/or alkali metal hydrides including (but not limited to) KH/C can be used in dehydrogenation processes of compounds including (but not limited to) propane. In certain embodiments, K/C and/or KH/C can cleave C-H bonds during dehydrogenation processes. In several embodiments, KH/C may act as a precursor and decompose to K/C at propane dehydrogenation (PDH) temperatures of at least 400 °C. Some embodiments provide that KH/C and K/C have similar reactivities for PDH.
[0046] In a number of embodiments, KH/C can participate in catalytic hydrogenation processes and provide hydrogen to compounds including (but not limited to) a!kynes and unsubstituted phenyl rings. Several embodiments provide that KH/C can cleave C-C bonds during hydrogenation processes. Certain embodiments provide KH/C can convert alkynes to olefins, without forming significant amounts of alkanes. In some embodiments, KH/C can catalyze hydrogenation of unsubstituted phenyl rings including (but not limited to) biphenyl. Certain embodiments provide that phenyicyclohexane can be a secondary product formed via hydrogenation of biphenyl. Several embodiments provide that the subsequent hydrogenation of phenyicyclohexane to bicyciohexane on KH/C can proceed under a higher pressure of hydrogen.
[0047] Some embodiments provide that alkali metal including (but not limited to) K can be mixed with H in a 1 :1 ratio in the DS, DM, DO, DH, and hydrogenation processes. In several embodiments, the molar ratio between K and H can be greater than 0 and less than or equal to 1. Any ratio between K and H greater than 0 and no greater than 1 in accordance with certain embodiments may work in DS, DM, DO, DH, and hydrogenation processes. K/C (the ratio between K and H is 1 :0) can participate in DS, DN, DO, and hydrogenation processes, but the activities of KH/C and K/C differ. K/C and KH/C may have similar activities during DH processes in accordance with several embodiments. Many embodiments provide that the amount of KH/C used in the reactions can affect the conversion efficiency and the yields of products. In a number of embodiments, KH/C may have higher conversion yields of DBT and DBT derivatives than KH.
[0048] DS, DM, and DO reactions can take place under an inert gas including (but not limited to) argon, helium, and nitrogen, or under hydrogen (H2) gas. DS processes under H2 pressure can stabilize KH/C. When DS of DBT is performed under a H2 atmosphere, KH/C may participate in catalytic hydrogenations of aromatic substrates including (but not limited to) biphenyl to form phenyicyclohexane. Several embodiments provide that lower hydrogen pressure may lead to a lower desulfurization efficiency. Methane pretreated K/C in accordance with several embodiments may have a higher DS activity than K/C and/or KH/C at low temperatures including (but not limited to) about 30 °C. In some embodiments, DH reactions can take place under an inert gas including (but not limited to) argon, helium, and nitrogen.
[0049] Systems and methods for DS, DN, DO, DH, and hydrogenation processes that utilize various alkali metal containing materials in accordance with various embodiments of the invention are discussed further below. Desu!furization
[0050] Fossil fuels contain naturally occurring organosulfur impurities, with quantities varying depending on the type of feedstock. These sulfur-containing organic small molecules can poison catalytic converters and generate polluting sulfur dioxides when combusted. Desulfurization (DS) is the industrial process by which sulfur impurities are removed from petroleum fractions prior to their use as fuels. DS may rely on heterogeneous catalysts such as M0S2/AI2O3 promoted with cobalt or nickel. These catalysts are typically utilized at about 400 °C under h½ pressures of up to 100 bar. (See, e.g., J. N. D. de Leon, et al., Catalysts ; 2019, 9; the disclosure of which is incorporated herein by reference). HDS can be performed by treating petroleum with H2 at high pressures and temperatures (for example, H2 pressures about 150-2,250 psi and about 400 °C) over heterogeneous catalysts such as cobalt-doped molybdenum sulfide supported on alumina (CoMoSx/v-AteCh) (See, e.g., Prins, R. et al., Catai. Today , 2008, 111 , 84-93; the disclosure of which is incorporated herein by reference). FIG. 1 illustrates an industrial DS process with CoMoSx/AbOs as catalyst.
[0051] Even under high temperature and high H2 pressure conditions, the removal of certain organosulfur species including (but not limited to) alkylated DBTs, such as 4,6- Me2DBT or 4,6-Et2DBT by HDS can be challenging. FIG. 2 illustrates chemical structures of DBT and DBT derivatives (DBT-SO, DBT-SOa, 4-MeDBT, and 4,6-iyie2DBT). Because HDS is energy intensive, there is a need in alternative routes that are more environmentally friendly. Homogeneous strategies for the reductive DS under mild conditions employing sophisticated, well-defined transition metal complexes including those based on platinum, nickel, tungsten, molybdenum, palladium, ruthenium, rhodium, iron, cobalt, and others have been investigated. One early approach relies on excess of Raney-Ni. (See, e.g., J. Rentner, et a!., Tetrahedron 2014, 70, 8983-9027; the disclosure of which is incorporated herein by reference). Alternatively, stoichiometric amounts of alkyl Grignard reagents or an organosilane (such as EtMe28iH) in a combination with a Ni-based catalyst, have been applied for DS of aryl methyl thioethers. (See, e.g., E. Wenkert, et al., J. Org. Chem. 1985, 50, 1125-1126; N. Barbero, et al., Org. Lett. 2012, 14, 796-799; the disclosures of which are incorporated herein by references). Alkali metals (such as Li, Na, K) have been used in DS reactions as well, including desulfurization of petroleum residues and coal. (R. Gerdil, et aL, J. Chem. Soc. 1963, 2857-2861; R. Gerdil, et ai., J. Chem. Soc. 1963, 5444-5448; J. L. Dye, et a!. , J. Am. Chem. Soc, 2005, 127, 9338-9339; the disclosures of which are incorporated herein by references). While alkali metals may be effective for the DS of alkylated dibenzothiophenes, yielding biaryis and alkali metal sulfides, an excess of an alkali metal (at least 10-fold more) is often needed and the reaction involves an aqueous workup when Li and Na are used. Table 1 lists experiment results from literatures of the desulfurization of DBT and its derivatives using Li and Na metals. (See, e g., H. Gilman, et aL, J. Am. Chem. Soc. 1953, 75, 2947-2949; Z. K. Yu, et a!. , Energy Fuels 1999, 13, 23-28; D. P. Morales, et aL, Molecules 2010, 15, 1285-1289: M. Pittalis, et aL, Tetrahedron , 2013, 69, 207-211; A. Kaga, et a!., Chem. Eur. J. 2021, 27, 4567-4572; the disclosures of which are incorporated herein by references). In Table 1, the molar ratio refers to the molar ratio between the substrate (S) and the alkali metal (Li/Na). RT refers to room temperature ranging from 20 °C to 25 °C.
Table 1. Results of the desulfurization of DBT and its derivatives using Li and Na metals.
Figure imgf000014_0001
Figure imgf000015_0001
[0052] Toutov, A.A., et al., have reported a potassium (K) alkoxide (G)/hydrosilane (Si)-based (‘KOSi’) system that desulfurizes refractory sulfur heterocycles (See, e.g., Toutov, A. A., et al., Nature Energy, 2017, 2, 17008; the disclosure of which is incorporated herein by reference). The DS method that operates under KOSi (KOtBu/silane) conditions may not require the use of organometallic complexes or inorganic transition metal species. A mixture of potassium tert- butoxide and triethylsiiane (1 :1 ratio, also called Grubbs-Stoltz reagent) can be used. FIG. 3 illustrates the reaction scheme of KOSi desulfurization reaction. The DS reactions occur at about 165 °C for about 40 hours and utilize three equivalents of the KO-fBu/EfsSiH reagent per one mol of a substrate. The Grubbs-Stoltz reagent can have a high DS efficiency with alkylated dibenzothiophenes, similar to the efficiency when using the alkali metals. For instance, the KO-fBu/EtaSiH reagent allows to lower the content of 4,8~Me2DBT in the spiked diesel from about 10000 ppm to about 2.4 ppm, although in this case a 0.5 M concentration (i.e,, a large excess) of KO-tBu and Et3SiH has been used. The application of KO-tBu with Et3SiH for DS may provide, at least initially, a homogeneous reaction mixture. Unfortunately, this leads to a high concentration of K and Si species in solution after the DS reaction, which may hinder the applicability of this method for the DS of fuels. KOtBu and EtsSiH used in the KOSi method are not economical to apply to industrial applications. Cheaper desulfurization conditions for HDS processes may be needed for practical applications.
[0053] Palumbo et ai. has reported that KO-fBu/EtsSiH can generate potassium hydride at about 130 °C (See, e.g., F. Palumbo, et ai,, Helv. Chim. Acta 2019, 102, ei 900235; the disclosure of which is incorporated herein by reference.) This result suggests that KH may play an important role in the DS activity of the Grubbs-Stoltz reagent.
[0054] In general, the DS activity of KH remains underexplored. One study from Vorapattanapong A. has reported partial desulfurization of DBT in the presence of potassium hydride (KH) (See, e.g., Vorapattanapong A., Potassium Hydride-mediated Hydrodesulfurization Catalyzed by Cobalt, Ph.D. thesis; the disclosure of which is incorporated herein by reference). The method shows that KH, acting as a reductant, can be competent for the hydrogenolysis of C-S bonds. However, the method only partially desulfurizes DBT with preferential cleavage of one C-S bond. FIG. 4 illustrates the reaction scheme of KH partial desulfurization reaction. Vorapattanapong reported that heating DBT with 2.5 equiv. of KH in THF (110 °C, 16 hours) can lead to 2- phenylthiopheno! in 78% yield and biphenyl in 10% yield at >99% conversion of DBT. Performing this reaction under 34 bar of H2 and at otherwise identical conditions lowers conversion of DBT to 93% and yields 2-phenylthiopheno! and biphenyl in 81 % and 1 %, respectively. In this method, the presence of added H2 has a minimal effect on the KH- induced C-S bond cleavage.
Desulfurization of Organosulfur Substrates
[0055] The industrial removal of organosulfur impurities from fossil fuels normally relies on transition metal-based catalysts in harsh conditions (for example, about 400 °C, up to 100 bar H2), yet DS of refractory alkyl DBTs remains challenging. Many embodiments provide desulfurization of C-S bonds in various organosulfur substrates including (but not limited to) refractory dibenzothiophene, dibenzotbiophene and/or dibenzothiophene derivatives under mild conditions. The desulfurization processes in accordance with several embodiments are transition-metai-free and silane free. Some embodiments provide alkali metal hydride including (but not limited to) potassium hydride (KH) to activate hydrogen for DS reactions. KH can be supported by a substrate containing carbon including (but not limited to) graphite to form KH on graphite (KH/C) in accordance with certain embodiments. In some embodiments, carbon-supported potassium hydride (KH/C) enables reductive desulfurization of C-S bonds in organosulfur substrates. Several embodiments provide that KH/C can act as a stoichiometric reagent in desulfurization. In some embodiments, KH/C can act as a reductant to desulfurize suifur-containing organic molecules including (but not limited to) dibenzothiophene and/or dibenzothiophene derivatives. Many embodiments provide that KH/C is able to achieve ultra-deep desulfurization. In some embodiments, KH/C can reduce sulfur content of dibenzothiophene and dibenzothiophene derivatives to low ppm levels. A number of embodiments provide that potassium-containing molecular compounds including (but not limited to) potassium bis(trimethy!silyl)amide (KHMDS) can be used to replace silane and/or transition metals in DS reactions.
[0056] Several embodiments provide that desulfurization processes can occur under mild conditions including (but not limited to) temperature starting from about 50 °C and less than about 165 °C. Yields of desulfurized hydrocarbons obtained using KH/C in hydrocarbon solvents in accordance with some embodiments can exceed about 90%. In several embodiments, at least 97% of DBTs can be converted at no higher than about 165 °C less than about 6 hours. Some embodiments provide the conversion of DBTs at about 165 °C takes place in about 3 hours to about 6 hours. The yields of respective biphenyls from DBTs conversions in accordance with certain embodiments can be from about 84% to about 95%. In many embodiments, no greater than 15% excess of KH per a C-S bond is applied in the DBTs conversion. The high yields of desulfurization can be achieved with about 15% molar excess of KH per C-S bond, without leaching of K into solution. [0057] Several embodiments provide conversion of DBT derivatives including (but not limited to) 4,6-Me2DBT with carbon-supported KH/C in mild conditions. The conversion of 4,6-IVie2DBT can take place at not higher than about 165 °C and no greater than about 20 hours. In a number of embodiments, KH/C enables to lower the concentration of 4,8- MeaDBT in the mesityiene solution from about 1000 ppm to less than about 3 ppm. Some embodiments provide that the monomethyl DBTs, dimethyl DBTs, and diethyl DBTs may produce biaryis during DS. Several embodiments provide that KH/C enables chemoselective DS of diaryl thioethers in preference to diaikyl thioethers.
[0058] Many embodiments provide that KH/C can catalyze hydrogenation of an unsubstituted phenyl ring in biphenyl derivatives to form a cyclohexyl group under about 10 bar of H2. Some embodiments provide that KH/C may remove other heteroatoms using dibenzofuran and 9-phenylcarbazole that undergo deoxygenation and denitrogenation reactions. In several embodiments, incorporation of deuterium into desulfurized products can take place when KH/C is applied in toluene-ds.
[0059] FIG. 5 illustrates a reaction scheme of desulfurization with carbon-supported potassium hydride in accordance with an embodiment of the invention. Organosuifur substrate 501 can be DBT or alkylated DBTs. R1 and R2 groups in the organosuifur substrate 501 can be hydrogen or alkyl groups. The desulfurization takes place under a temperature of less than about 165 °C. The organosuifur substrate 501 can be reduced and the C-S bond can be removed.
[0060] While various processes for desulfurization using alkali metal containing materials are described above with reference to FIG. 5, any variety of processes that utilize alkali metal containing materials to cleave C-S bonds can be utilized in the desulfurization processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of desulfurization of dibenzothiophene in accordance with various embodiments of the invention are discussed further below.
Desulfurization of Dibenzothiophene on Alkali Metal Hydrides [0061] Many embodiments provide desulfurization of of dibenzothiopbene using carbon-supported alkali metal hydride including (but not limited to) KH/C. Several embodiments provide that KH/C can act as a stoichiometric reagent in desulfurization. FIG. 8 illustrates desulfurization of DBT in accordance with an embodiment of the invention. DBT 801 can be reduced and form biphenyl 802 and phenylcyclohexane 803 at different selectivity and/or yields respectively under various reaction conditions. Different DBT desulfurization conditions result in different conversion efficiency of DBT. DBT desulfurization conditions can include, mesityiene as a solvent, reaction temperature between about 50 °C and about 185 °C, reaction time from about 1 hour to about 40 hours, under about 10 bar Ar or about 10 bar H2, with KH/C or K/C.
[0062] Several embodiments provide DBT reaction conditions for DS using KH/C compared to K/C and commercial KH. In some embodiments, a 0.03 M solution of DBT in mesityiene can be stirred for about 20 hours with about 1.15 equiv. of KH/C or K/C per C--S bond of DBT while the temperature varies from about 50 °C to about 165 °C. Molar ratio of K (in KH/C or K/C) to DBT can be about 2.3 : 1. A standard (tridecane) can be added after the reaction, the reaction mixture can be filtered and conversion of DBT and yields of formed products can be quantified by gas chromatography-mass spectrometry (GC-MS).
[0063] DBT can have different conversion percentage under different reaction conditions of the desulfurization reaction. FIG. 7 A illustrates DS reaction with KH/C and K/C under about 10 bar Ar at temperature between about 50 °C and about 185 CC in accordance with an embodiment of the invention. DBT conversion on K/C is shown in curve 701. DBT conversion on KH/C is shown in curve 702, Yield of biphenyl on KH/C is shown in curve 703. Yield of biphenyl on K/C is shown in curve 704. DS of DBT provides biphenyl as the only product at about 50 °C, obtained in about 8% yield (703) at about 11 % conversion of DBT (702). At about 130 °C, conversion of DBT is almost 100% (702) and biphenyl is obtained in about 79% yield with KH/C (703), With KH/C, the DS can have a yield of biphenyl of about 70% and no other product is detected (703). In contrast to commercial KH (not shown), only about 26% conversion of DBT and about 17% yield of biphenyl is observed with at 165 °C. The lower yield of biphenyl with KH/C at 185 °C reiative to 130 °C may be due to the increased reactive adsorption of DBT (or intermediates to form biphenyl) onto the KH/C material, possibly owing to a partial decomposition of KH to K and hte on KH/C at the higher used reaction temperature. Reactive adsorption of DBT can be stronger on K/C compared to KH/C since below 80 °C. conversion of DBT on K/C is about two times higher than that on KH/C (62% and 32%), yet the yields of biphenyl are comparable (25% and 27%). A similar trend is also observed at 130 °C and 165 °C. K/C shows a complete conversion of DBT but lower yields of biphenyl compared to KH/C, likely owing to a higher amount of species formed due to the reactive adsorption of DBT on K/C (703 and 704). The decomposition of KH/C to K/C after treating KH/C at about 165 °C for about 20 hours in mesitylene is consistent with the lack of detected Ha in an Ar~TPD experiment of the dried recovered material. [0064] Several embodiments provide that DS processes under H2 pressure can stabilize KH/C. When DS of DBT is performed under a H2 atmosphere, biphenyl and phenylcyclohexane can form. FIG. 7B illustrates DS reaction on KH/C under about 10 bar H2 at temperature between about 50 °C and about 165 °C in accordance with an embodiment of the invention. DBT conversion on KH/C is shown in curve 705. Yield of biphenyl on KH/C is shown in curve 706. Yield of phenylcyclohexane on KH/C is shown in curve 707. With increase of the reaction temperature from about 50 °C to about 130 °C, the yield of phenylcyclohexane (707) gradually increases from about 0% to about 12% before raising sharply to about 84% at about 165 °C. The yield of biphenyl (706) increases from about 9% at about 50 °C to about 54% at about 130 °C and then it decreases to about 0%. This is probably due to the hydrogenation of biphenyl to phenylcyclohexane above 130 °C.
[0065] The desulfurization of DBT using KH/C can be compared at 100 °C and 165 °C under 10 bar of H2 in accordance with several embodiments. FIG. 7 C illustrates DS reaction at various time points with KH/C under about 10 bar H2 at about 100 °C. DBT conversion on KH/C is shown in curve 711. Yield of biphenyl on KH/C is shown in curve 712. Yield of phenyl cyclohexane on KH/C is shown in curve 713. After about 40 hours at about 100 °C, biphenyl and phenylcyclohexane form in about 59% and 7% yields respectively (712 and 713), at about 79% conversion of DBT (711 ). The low yield of phenylcyclohexane indicates that the hydrogenation reaction is slow at about 100 °C. [0066] FIG. 7D illustrates DS reaction at various time points with KH/C under about 10 bar H2 at about 165 °C. DBT conversion on KH/C is shown in curve 714. Yield of biphenyl on KH/C is shown in curve 716. Yield of phenyl cyclohexane on KH/C is shown in curve 715. The conversion of DBT reaches about 82% after about 1 hour at about 165 °C (714), and yields of biphenyl and phenylcyclohexane are about 61 % and 8% respectively (715 and 716). Conversion of DBT is full after about 3 hours at about 165 °C (714) and yields of biphenyl and phenylcyclohexane are 71 % and 19% respectively (715 and 718). Longer reaction times may lead to consumption of biphenyl by its hydrogenation to phenylcyclohexane. Almost no biphenyl can be detected after about 20 hours of reaction whereas the yield of phenylcyclohexane is about 84%. In contrast, commercial KH gives about 10% conversion of DBT and about 7% yield of phenylcyclohexane in these conditions. Table 2 lists comparison of DS of DBT on KH/C and commercial KH. KH/C has better DS activities compared to commercial KH. Some embodiments provide that the better reactivity of KH/C may be due to smaller particle sizes of KH in KH/C relative to the commercial KH. A smaller particle sizes means a larger surface area, i.e., a higher contact area with molecules in solution (solvent and a substrate for DS), Certain embodiments provide that the better reactivity of KH/C may also be related to a support effect. If the DS reaction involves an electron transfer from KH/C to the S-containing substrate molecule, or to a solvent molecule first, and then to the substrate, this transfer may take place from the adsorption sites of the C support, and not from the adsorption sites on KH, provided that electrons can flow from KH to the C support (which is conductive). So support may function as an electron transfer reagent. The DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time about 20 hours, under about 10 bar Ar or about 10 bar Hs, with KH/C or commercial KH. The ratio of KH/C or KH is about 1.15 equivalent per C-S bond.
Table 2. Comparison of DBT desulfurization on KH/C and commercial KH.
Figure imgf000022_0001
[0067] DBT can be reduced and form biphenyl at different selectivity and/or yields under various reaction conditions. Reaction conditions including (but not limited to) temperature and reaction time can influence selectivity and/or yield of biphenyl and conversion of DBT. In some embodiments, biphenyl is the only product detected by gas chromatography (GC) when reaction is conducted under inert gas. Several embodiments provide that KH/C might be a potent hydrogen donor for stoichiometric desulfurization of DBT. Several embodiments provide that lower hydrogen pressure may decrease the hydrogenation rate of biphenyl to phenyicyclohexane. Lower hydrogen pressure including (but not limited to) 2 bar and 5 bar may lower the yield of phenyicyclohexane on KH/C after about 20 hours to about 7% (at 2 bar) or about 38% (at about 5 bar). Biphenyl can be the major product formed at the complete conversion of DBT. Table 3 lists conversion percentage and yields at various hydrogen partial pressure during the desulfurization of DBT on KH/C. The DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time about 20 hours, with KH/C. The ratio of KH/C is about 1.15 equivalent per C-S bond. Reactions run under a constant total pressure of 10 bar but with different H2 partial pressures. Total pressure can be balanced by Ar.
Table 3. Influence of H2 partial pressure on the desulfurization of dibenzothiophene on KH/C.
Figure imgf000023_0001
[0068] Many embodiments provide that phenyicyciohexane can be a secondary product formed via hydrogenation of biphenyl. Several embodiments provide that the subsequent hydrogenation of phenyicyciohexane to bicyclohexane can proceed at a higher pressure of hydrogen. Catalytic hydrogenation processes with KH/C are discussed in details in a following section.
[0069] Some embodiments provide XRD profiles of the used KH/C material collected after the desulfurization reaction of DBT. FIG. 8 illustrates XRD of KH/C collected after the desulfurization of dibenzothiophene in mesitylene in accordance with an embodiment of the invention. Reaction can be performed at about 185 °C in H2 for about 20 hours. XRD of KH/C at about 185 °C, about 20 hour, about 10 bar H2, shows peaks attributed to K2S on C. HADDF-8TEM images and EDX mappings show the high dispersion of K and S on the KH/C as well as on the K/C (165 °C, 20 h, 10 bar Ar) after the desulfurization reaction.
[0070] Many embodiments provide that the amount of KH used in the DS reactions can affect the conversion of DBT and the yields of products. In certain embodiments, decreasing by two fold the amount of used KH per mol of DBT, such as from about 2.3:1 to 1.15:1 , can lower the conversion of DBT from complete to about 48% (185 °C, 20 h and 10 bar H2). The distribution of products may change as well. When KH per mol of DBT (KH/C : DBT) changes from 2.3:1 to 1.15:1 , the yield of phenyicyciohexane may change from about 84% (as a sole product) to about 5%. Biphenyl increases to about 40% with the 1.15:1 ratio of KH/C: DBT. When the 1.15:1 molar ratio of KH/C:DBT is used, most of KH/C may be converted to K28/C, and K2S/C can be inactive in hydrogenation of biphenyl to phenylcydohexane. Table 4 lists dependence of the product selectivity on the ratio of DBT to KH/C. The reactions use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under about 10 bar H2, with KH/C.
Table 4. Dependence of the product selectivity on the ratio of DBT : KH/C.
Figure imgf000024_0001
[0071] Several embodiments provide that spent KH/C is less effective in converting DBT in DS processes. Spent KH/C can be recovered and treated under 100 bar of H2 at about 200 °C for 20 hours. The use of spent KH/C in the second DS cycle gives about 1 % conversion of DBT. The unfavorable thermodynamics for regenerating KH (or K) from K2S via the thermal treatment in H2 at relatively low temperatures may cause the low conversion. Table 5 lists desulfurization of DBT with reused KH/C. The DS reactions use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under about 10 bar H2. with KH/C.
Table 5. Desulfurization of DBT with reused KH/C.
Figure imgf000024_0002
[0072] In many embodiments, DS of DBT can be performed using KH/C and K/C in toluene-dg to provide the H/D exchange with the solvent under Ar atmosphere. At about 2-6% conversion of DBT and about 1 % yield of biphenyl, deuterium incorporation into biphenyl may not be observed using either KH/C or K/C as the distribution of the mass- to-charge ratios of biphenyl obtained in toluene-de may not differ from that in mesitylene. However, when conversion of DBT reaches about 10% to about 33% (about 20 hours at about 50 °C), a partial incorporation of deuterium into biphenyl can be observed with both KH/C and K/C in accordance with several embodiments. FIG. 9 illustrates distribution of deuterated products of desulfurization of DBT on KH/C or K/C in toluene-ds in accordance with an embodiment of the invention. The distribution of deuterated products of desulfurization of DBT (using the molar ratio of K : DBT = 2.3 : 1 ) under different reaction conditions are illustrated in 901 , 902, and 903. The reaction conditions of 901 is at about 50 °C in Ar for about 7 hours. The reaction conditions of 902 is at about 50 °C in Ar for about 20 hours. The reaction conditions of 1003 is at about 165 °C in Ar for about 20 hours. A partial incorporation of deuterium into biphenyl can be seen by the appearance of peaks with m/z higher than about 154, for example, up to m/z = 159 for K/C and m/z = 164 (minor peak) for KH/C (903). An intense peak at m/z = 164, i.e. , from the fully deuterated biphenyl, can be observed on KH/C at the full conversion of DBT and about 74% yield of biphenyl after 20 hours at about 165 °C (903). In these conditions, K/C gives about 52% yield of biphenyl with a broad distributions of m/z ratios, up to m/z = 164 (903). These results indicate that the incorporation of deuterium into biphenyl on KH/C is faster than on K/C.
[0073] FIG. 10 illustrates distribution of deuterated products of hydrogenation of biphenyl in different conditions in accordance with an embodiment of the invention. FIG. 10 illustrates a blank experiment (without KH/C) in toiuene-ds (1001 ), with KH/C in toluene-ds (1002 and 1003), and with KH/C in benzene-de (1004 and 1005). The reaction conditions include molar ratio of K:DBT at about 2.3:1 , in Ar, at about 165 °C for about 20 hours. FIG. 10 shows that the H/D exchange between biphenyl and toluene-ds can lead to fully deuterated biphenyl (m/z = 164) and phenylcyciohexane (m/z = 176) when heating biphenyl with KH/C in toiuene-ds (165 °C, 20 hours). The H/D exchange proceeds simi!ariy when using benzene-de as the solvent instead of to!uene-ds (1002, 1003, 1004, 1005). No deuteration of DBT can be observed in any of the reaction mixtures above. [0074] FIG. 11 illustrates distribution of deuterated products of deoxygenation of dibenzofuran on KH/C in toluene-ds in accordance with an embodiment of the invention. 1101 illustrates standard mass spectrometry of non-deuterated 2-pheny!phenoi. 1102 illustrates mass spectrometry of deuterated 2-pbenyiphenol products (conversion of dibenzofuran is 100%; yield of 2-pheny!phenoi is 76%). Reaction conditions include at about 165 °C in Ar for about 3 hours, using the molar ratio of K : DBF of about 2.3 : 1. When deoxygenation of dibenzofuran performed in toluene-ds at about 165 °C in Ar for about 3 hours, deuterium incorporation into 2-phenylphenoi is also observed, giving m/z of 2-pheny!phenol distributed from 170 to 180 (1101 and 1102). KH has been reported to catalyze the H/D exchange, i.e. , exchange between D2 and toluene (or H2 and toluene- ds) under reflux and 5 bar H2/D2
[0075] Several embodiments provide desulfurization activities on various potassium based materials including (but not limited to) KH/C, K/C, and methane pretreated K/C. Many embodiments provide that DS of DBT can occur in an inert gas including (but not limited to) argon, nitrogen, and helium, in hydrogen gas, or in methane gas. In several embodiments, K/C can be pretreated in methane. Methane pretreated K/C can remove almost 100% DBT at low temperature including (but not limited to) about 30 °C. At low temperatures, methane pretreated K/C may have better DS activity than K/C, and K/C may have better DS activity than KH/C. Some embodiments provide that methane pretreatment temperature may affect DS activity. Table 6 lists DS of DBT with different potassium based materials. The reaction conditions include mesitylene as a solvent, under about 10 bar of Ar or CH4, for about 20 hours.
Table 6. Desulfurization of DBT with different potassium based materials.
Figure imgf000027_0001
[0076] While various processes for desulfurization of DBT using carbon-supported alkali metal hydrides are described above with reference to FIG. 6 - FIG. 11 any variety of processes that utilize carbon-supported alkali metal hydrides can be utilized in the DBT desulfurization processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of desulfurization of DBT with molecular potassium compounds in accordance with various embodiments of the invention are discussed further below. Desulfurization of Dihenzothiophene with Molecular Potassium Compounds [0077] Many embodiments provide molecular compounds of alkali metal including (but not limited to) KHMDS in the presence of hydrogen gas could replace silane in DS of DBT. In several embodiments, KHMDS can cleave C-S bonds in heteroaromatic compounds and remove S. FIG. 12 illustrates DS of DBT with KHMDS in accordance with an embodiment of the invention. DBT 1201 can be reduced and form biphenyl 1202 and phenyl cyclohexane 1203 at different selectivity and/or yields under various reaction conditions,
[0078] Table 7 lists various reaction conditions of DBT with KHMDS. DS of DBT with the KHMDS and Ha system may be more efficient in aliphatic n~ octane relative to the tested aromatic solvents (Table 7, entries 3, 8, 9, 10). Several embodiments provide that sulfur removal may be stochiometric on KHMDS, but the utilization of potassium for DS can be high. In some embodiments, only a minor molar excess of KHMDS may be required for the complete conversion of DBT. In such embodiments, the efficiency of the KHMDS and H2 system can be comparable to that of the KH/C systems. However, the product selectivity may differ. For example, the overhydrogenation of the aromatic ring may not be observed using KHMDS and H2 systems. The yield of biphenyl may increase at a higher hydrogen pressure (Table 7, entries 3, 5, 7).
Table 7. Desulfurization of DBT with KHMDS.
Figure imgf000028_0001
Figure imgf000029_0001
[0079] While various processes for desulfurization of DBT using molecular potassium compounds are described above with reference to FIG. 12, any variety of processes that utilize molecular potassium compounds can be utilized in the DBT desulfurization processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of desulfurization of sulfur-containing compounds with alkali metal hydrides in accordance with various embodiments of the invention are discussed further below.
Desulfurization of Dibenzothiophene Derivatives and Sulfur-containing Compounds with Alkali Metal Hydrides
[0080] Many embodiments provide desulfurization on carbon-supported alkali metal hydrides including (but not limited to) KH/C of dibenzothiophene derivatives including (but not limited to) alkylated dibenzothiphene using KH/C. Alkylated DBTs include (but are not Simited to) 4-methyldibenzothiophene (4-MeDBT), 4,6-dimethyldibenzothiophene (4,6- MeaDBT), and 4,6-diethyldibenzothiophene (4,6-Ei2DBT). Several embodiments provide desulfurization of sulfur-containing compounds on KH/C including (but not limited to) dibenzothiophene suifone, diphenyl sulfide, 2-phenyithiophenol, polyphenylene sulfide, and di~/?~octyl sulfide. Some embodiments provide that KH/C is able to achieve ultra-deep desulfurization. In certain embodiments, KH/C can reduce sulfur content of dibenzothiophene and dibenzothiophene derivatives to low ppm levels.
[0081] Several embodiments provide that the monomethyl DBTs, dimethyl DBTs, and diethyl DBTs may proceed smoothly during DS and produce biary!s. FIG. 13 illustrates a DS reaction scheme of alkylated DBTs in accordance with an embodiment of the invention. Alkylated DBT 1301 can have different groups in R1 and R2 positions. R1 can be a hydrogen, a methyl, or a diethyl group. R2 can be a hydrogen, a methyl, or a diethyl group. The DS process can produce biaryls 1302 and phenyl cyclohexane 1303. Alkylated DBT desulfurization conditions can include, mesitylene as a solvent, reaction temperature of about 165 °C, reaction time from about 6 hour to about 20 hours, under about 10 bar Ar or about 10 bar Hs, with KH/C. The DS process can use about 1.15 equivalent of KH/C per C-S bond.
[0082] Table 8 lists reaction conditions and product yields of desulfurization of various alkylated DBTs. Table 8 lists conversion rate of alkylated DBT, the yield of biaryls, and the yield of phenyl cyclohexane under different conditions. Several embodiments provide that the yield of biaryls can be from about 91 % to about 95% after about 6 hours at about 185 °C under Ar. Yields from about 82% to about 90% of biaryls can be obtained when decreasing the reaction temperature to about 130 °C. Desulfurization of 4-MeDBT may yield about 23% biaryl due to the hydrogenation of the unsubstituted phenyl ring, when Ar atmosphere is replaced by H2 (Table 8, entry 4). Biary! may not be formed during DS of 4,6-Me2DBT and 4,6-Et2DBT, showing that alkyl-substituted phenyl rings may not hydrogenated using KH/C in those conditions (Table 8, entries 5-6).
Table 8. Desulfurization of alkylated dibenzothiophenes.
Figure imgf000031_0001
[0083] Several embodiments provide desulfurization of compounds including (but not limited to) dibenzothiopbene su!fone, diphenyl sulfide, 2-pheny!thiophenol. and polyphenylene sulfide. In some embodiments, KH/C can desulfurize aliphatic di-/?-octyl sulfide to /?~octane. FIG. 14 illustrates a desulfurization reaction scheme of aliphatic d\-n- octyi sulfide in accordance with an embodiment. The DS reactions may use cyclohexane as a solvent, reaction temperature at about 165 °C, reaction time of about 3 hours, under Ar, with KH/C at 1 .15 equivalent per C-S bond. The desulfurization with KH/C can achieve about 92% yield at a full conversion of aliphatic di-n-octyl sulfide, when the reaction is performed in cyclohexane at about 165 °C for about 3 hours in Ar. Several embodiments provide that dia!ky!su!fides including (but not limited to) aliphatic di-n-octyl sulfide, may be challenging substrates for the DS with sodium. Certain embodiments provide that no observed desulfurization processes take place when (n-CeH 13)28, (n-CeHi7)2S and (/?- Ci2H25)2S are heated with Na at about 110 CC or at about 164 °C. However, increasing the temperature to about 254 °C (in tetradecane) may yield the corresponding alkanes in high yields with small amounts of the corresponding alkyithiois. No observed conversion of aliphatic di-n-octyl sulfide can be made when the reaction takes place in mesityiene at a temperature about 165 °C, with a reaction time about 20 hours, under about 10 bar Ar or H2. The observation may be due to the stronger adsorption of mesityiene relative to di-n-octyi sulfide on KH/C, and also due to the higher concentration of mesityiene in solution.
[0084] Some embodiments provide that 4,6-Me2DBT and aliphatic di-/?-octyl sulfide may be desulfurized using KH/C. FIG. 15 illustrates a desulfurization scheme of 4,6- Me2DBT and aliphatic di-n-octy! sulfide in accordance with an embodiment of the invention. Table 9 lists desulfurization of 4,8-Me2DBT and aliphatic di-n-octyl sulfide with different molar ratios and in different solvents. In some embodiments, a chemose!ective DS of 4,6-Me2DBT may occur when an equimolar mixture of 4,6-Me2DBT and aliphatic di-n-octyl sulfide is treated with KH/C in mesityiene (Table 9, entry3). Certain embodiments provide that when this reaction is conducted in cyclohexane, both 4,6- MezDBT and aliphatic di-n-octyl sulfide may undergo desulfurization (Table 9, entry 4).
Table 9. Desulfurization of 4,6-Mb2qBT and aliphatic di-n-octyl sulfide with KH/C.
Figure imgf000032_0001
[0085] Many embodiments provide desulfurization of dibenzothiophene sulfone using KH/C. FIG. 16 illustrates a desulfurization reaction scheme of dibenzothiophene sulfone in accordance with an embodiment of the invention. The DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 6 hours, under Ar, with KH/C at 3 equivalent per C-S bond, KH/C can provide desulfurization of dibenzothiophene sulfone with a yield of about 86% biphenyl at about 165 °C after about 6 hours under Ar in mesitylene, at 93% conversion of dibenzothiophene sulfone,
[0086] Several embodiments provide desulfurization of diphenyl sulfide using KH/C. FIG. 17 illustrates a desulfurization reaction scheme of diphenyl sulfide in accordance with an embodiment. The DS reactions may use mesityiene as a solvent, reaction temperature at about 200 °C, reaction time of about 20 hours, under Hz, with KH/C at 1.15 equivalent per C-S bond. The desulfurization reaction of diphenyl sulfide with KH/C in mesitylene, at about 200 °C, for about 20 hours, under Hz, may result in full conversion and about 61% yield of benzene. Table 10 lists desulfurization of diphenyl sulfide using KH/C in mesityiene under different reaction conditions. The DS reactions use mesitylene as a solvent, reaction temperature from about 130 °C to about 200 °C, reaction time of about 20 hours, under about 10 bar Ar or Hz, with KH/C at 1 .15 equivalent per C-S bond. Yield of benzene may decrease to about 40% and about 18% when reaction is performed at about 165 °C and about 130 °C, respectively (Table 10, entries 2 and 4). Conversion of diphenyl sulfide and yield of benzene may be consistently lower when Ar is used in place of Hz, disregard of the reaction temperature (130, 165 or 200 °C, Table 10, entries 1 , 3 and 5).
Table 10. Desulfurization of diphenyl sulfide using KH/C in mesityiene.
Figure imgf000033_0001
Figure imgf000034_0001
[0087] Some embodiments provide desulfurization of 2-phenyitbiopheno! on KH/C. FIG. 18 illustrates a desulfurization reaction of 2-phenyltbiophenol in accordance with an embodiment. The DS reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 20 hours, under Fte, with KH/C at 1 .15 equivalent per C-S bond. The reaction may take place at about 165 °C under H2, and lead to complete conversion of 2-phenylthiophenoi. Some embodiments provide about 22% yield of phenyl cyclohexane may be obtained. The low yield may be due to the strong adsorption of potassium thiophenolate on KH/C. Certain embodiments provide that stirring the reaction mixture with isopropanol may achieve a similar yield of phenyl cyclohexane.
[0088] Many embodiments provide desulfurization of polyphenylene sulfide (PPS) on KH/C. FIG. 19 illustrates a desulfurization reaction of PPS in accordance with an embodiment of the invention. FIG. 19 shows that PPS (1 ) can be desulfurized and generate benzene (2), cyclohexane (3), phenylcyclohexane (4), 1 ,3-dimethylbenzene (5), and a mixture of isomers of demetbyiated biphenyls (8). Table 11 lists desulfurization of PPS on KH/C in different conditions. The DS conditions may include 1.15 equivalent of KH/C per C-S bond. DS of PPS is carried out in various solvents: mesitylene, toluene, and n-octane. Some embodiments provide that DS activity of PPS on KH/C is higher in an aromatic solvent than in an aliphatic solvent. In certain embodiments, DS activity of PPS on KH/C is higher in H2 than those in Ar. C-C coupling product phenylcyclohexane (4) may be observed when reaction performed in H2; while production of biphenyl may not be observed. Cyclohexane (3) may be formed only in mesitylene. 1 ,3- dimethylbenzene (5) can be formed due to the demethylation of mesitylene. A mixture of isomers of demethylated biphenyls (6) may be formed in mesitylene due to coupling of the radicals of benzene and 1 ,3-dimethylbenzene, and its subsequent isomerization. A mixture of isomers of demethy!ated biphenyls (6) may be formed in toluene due to coupling of toluene radicals and its subsequent isomerization.
Table 11 . Desulfurization of PPS on KH/C in different conditions.
Figure imgf000035_0001
[0089] Many embodiments provide that KH/C can reduce sulfur content of dibenzothiophene and its derivatives to low ppm levels. In several embodiments, KH/C can reduce sulfur concentration of 4,6-Me2DBT to less than about 3 ppm. The concentration of [S] due to 4,6-Mb2qBT in the mesitylene solution can be lowered from about 1000 - 100 ppm to [S] less than 3 ppm. Table 12 lists [S] concentration in the solution before and after the ultra-deep desulfurization of 4,8-Me2-DBT. The ultra-deep desulfurization in accordance with some embodiments can take place with about 3 molar equivalents of KH/C at about 185 °C for about 20 hours (Table 12, entries 1-2). With about 10 ppm of [S] in solution, the ppm content about 2.4 ppm of 4,6-Me2DBT can be achieved with 12 equivalent of KH/C (Table 12, entry 3).
Table 12. Ultra-deep desulfurization of 4,8~l\/!e2~DBT using KH/C.
Figure imgf000036_0001
[0090] While various processes for desulfurization of sulfur-containing compounds using alkali metal hydrides are described above with reference to FIG. 13 - FIG. 19, any variety of processes that utilize alkali metal hydrides can be utilized in the sulfur- containing compounds desulfurization processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of desulfurization of DBT derivatives with alkali metal molecular compounds in accordance with various embodiments of the invention are discussed further below.
Desulfurization of Dibenzothioohene Derivatives with Molecular Potassium Compounds [0091] Many embodiments provide desulfurization of dibenzothiophene derivatives including (but not limited to) alkylated dibenzothiphene using molecular potassium compounds including (but not limited to) KHMDS. Alkylated DBTs include (but are not limited to) 4,6-dimethyldibenzothiophene (4,6~Me2DBT), and 4,6- diethyidibenzothiophene (4,6-Et2DBT). Many embodiments provide desulfurization reactivity of DBT derivatives on KHMDS: DBT > 4,6~Me2DBT > 4,6~Et2DBT. The relatively lower DS activity on alkylated DBT may be due to the steric effect of substituted alkyl groups. Such steric effect may not be observed with the KH/C system, where the DS efficiency may not depend on the steric bulk of DBT derivatives.
[0092] FIG. 20 illustrates a DS reaction scheme of alkylated DBTs with KHMDS in accordance with an embodiment of the invention. Alkylated DBT 2001 can have different groups in R1 and R2 positions. R1 can be a hydrogen, a methyl, or a diethyl group. R2 can be a hydrogen, a methyl, or a diethyl group. The DS process can produce biaryls 2002 and phenyl cyclohexane 2003. Table 13 lists desulfurization of alkylated DBT using KHIVIDS in hydrogen. The reaction conditions include: KHIVIDS is about 1.15 equivalent per C-S bond, solution is n-octane, reaction temperature about 165 °C, reaction time about 20 hours, under hydrogen gas.
Table 13. Desulfurization of various alkylated DBT using KHIVIDS.
Figure imgf000037_0001
[0093] While various processes for desulfurization of DBT derivatives using alkali metal molecular compounds are described above with reference to FIG. 20, any variety of processes that utilize alkali metal molecular compounds can be utilized in the DBT derivatives desulfurization processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of deoxygenation with alkali metal hydrides in accordance with various embodiments of the invention are discussed further below.
Deoxyaenatson
[0094] Many embodiments provide that KH/C can be used for the reductive cleavage of C — O bonds. In some embodiments, KH/C can convert dibenzofuran to 2-phenylphenol by cleaving the C-0 bonds. KH/C in accordance with several embodiments eliminates the use of transition metals and/or silane in deoxygenation processes. Deoxygenation processes with KH/C can undergo milder reaction conditions including (but not limited to) less amount of KH/C compared to other catalysts, lower reaction temperature and shorter reaction time. FIG. 21 A and FIG. 21 B illustrate reaction schemes of dibenzofuran conversion with KH/C in accordance with an embodiment. In FIG. 21 A, dibenzofuran can be converted to 2-phenyiphenol by KH/C. The reactions may use mesitylene as a solvent, reaction temperature at about 165 °C, reaction time of about 3 hours, under Ar, with KH/C at 1 .15 equivalent per C-0 bond. FIG. 21 B illustrates that dibenzofuran can be converted to 2-phenyiphenol, 2-cyclohexyiphenol, and phenyl cyclohexane by KH/C. Table 14 lists deoxygenation of dibenzofuran on KH/C under different conditions. The reactions may use mesitylene as a solvent, at a temperature of about 165 °C. reaction time from about 3 hours to about 8 hours, under about 10 bar Ar or H2, with KH/C at 1.15 equivalent per C-0 bond. KH/C may convert dibenzofuran at about 165 °C for about 3 hours with a conversion rate of about 100% and 76% under Ar and H2, respectively (Table 14, entries 1-2), About 1 % yield of 2-phenylpbenoi can be detected in the supernatant after the reaction. Several embodiments provide that stirring the reaction mixture with isopropanol may increase 2-phenylphenoi yield to about 83%. This suggests a strong adsorption of potassium aryloxide of 2-phenyiphenol on the reacted KH/C and its protonation by isopropanol. After reaction, about 0.3 mL isopropanol can be added to the reaction mixture and stir for about 3 hours at room temperature followed by filtration. When reaction is performed under H2 for about 8 hours, 2-cyc!ohexylpheno! may form in about 8% yield along with about 4% yield of phenyl cyclohexane (Table 14, entry 4).
Table 14. Deoxygenation of dibenzofuran on KH/C.
Figure imgf000038_0001
Figure imgf000039_0001
[0095] While various processes for deoxygenation of dibenzofuran using alkali metal hydrides are described above with reference to FIG. 21 A - FIG. 21 B, any variety of processes that utilize alkali metal hydrides can be utilized in the deoxygenation processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of denitrogenation with alkali metal hydrides in accordance with various embodiments of the invention are discussed further below.
Denitrogenation
[0096] Several embodiments provide that KH/C can be used for the reductive cleavage of C-N bonds. Many embodiments provide denitrogenation of 9- phenyicarbazole with KH/C. In some embodiments, KH/C can eliminate the use of transition metals and/or silane in denitrogenation processes. Denitrogenation processes with KH/C can undergo milder reaction conditions including (but not limited to) less amount of KH/C compared to other catalysts, lower reaction temperature and shorter reaction time. FIG. 22 illustrates a reaction scheme of denitrogenation of 9- phenylcarbazole in accordance with an embodiment of the invention. The reactions may use mesity!ene as a solvent, reaction temperature at about 185 °C, reaction time of about 20 hours, under H2, with KH/C at 0.78 equivalent per C-N bond. Table 15 lists denitrogenation of 9-phenylcarbazole with KH/C under different conditions. 9- phenylcarbazoie with KH/C in mesityiene at about 185 °C under Ar provides benzene as the detected product at about 35% yield and at about 35% conversion of 9- phenylcarbazole (Table 15, entry 1 ). In some embodiments, performing this reaction under H2 may increase conversion of 9-phenylcarbazole to about 49% and yield about 38% benzene, about 12% biphenyl, and about 8% phenylcyciohexane. Increasing the ratio of KH/C: 9-pheny!carbazole from 2.3:1 to 3.3:1 may not increase yield of products (Table 15, entries 3-4). Increasing H2 pressure from 10 to 100 bar may lead to a higher conversion of 9-phenylcarbazole, from about 49% conversion to about 80%, and yield about 51% yield of benzene and about 18% of phenylcyclohexane (Table 15, entry 5). Adding isopropanol to the reaction mixture of 9-phenylcarbazole may not lead to higher yields of products (Table 15, entry 6).
Table 15. Denitrogenation of 9-phenyl carbazoie on the KH/C,
Figure imgf000040_0001
[0097] While various processes for denitrogenation of 9~phenylcarbazo!e using alkali metal hydrides are described above with reference to FIG. 22, any variety of processes that utilize alkali metal hydrides can be utilized in the denitrogenation processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of dehydrogenation with alkali metal and alkali metal hydrides in accordance with various embodiments of the invention are discussed further below.
Dehydrogenation -0098] Many embodiments provide that alkali metal supported by carbon including (but not limited to) K/C can initiate dehydrogenation processes. In several embodiments, carbon-supported alkali metal hydride including (but not limited to) KH/C may participate in dehydrogenation processes. KH/C may act as a precursor and decompose to K/C at dehydrogenation temperatures of at least 400 °C. K/C in accordance with some embodiments can activate C-H bonds and remove hydrogen. Many embodiments provide dehydrogenation of propane with K/C and KH/C. K/C and KH/C may have similar reactivities during dehydrogenation of propane processes. Propane dehydrogenation (PDH) is a process of catalytic conversion of propane into propylene and hydrogen. FIG. 23 illustrates main target reaction and side reactions of PDH. Conventional PDH catalysts include K(Na)-Cr0x/Ai203 in the Catofin process, and K(Na)-Pt-Sn/Al203 in the Oleflex process. K(Na)-Cr0x/Ai203 can be toxic and can be deactivated quickly. K(Na)-Pt- Sn/AbGs can be high cost, and may have high tendency to sintering and to form coke. [0099] Many embodiments provide the transition-metai-free K/C and/or KH/C systems to activate C-H bonds in CsHs for PDH processes. K/C and KH/C can have high conversion rate of propane. Propane (C3H8) dehydrogenation with K/C can generate propylene (C3H6), ethane (C2H6), ethylene (C2H4), and methane (CH4).
[00100] Several embodiments provide that at about 400 °C, 30 wt.% K/C may have conversion efficiency of about 30% of C3H8 and CH4 selectivity of about 80% at the initial stage. Some embodiments provide that at about 500 °C, CsHe selectivity may be lower. FIGs. 24A - 24D illustrate conversion and product yields during propane dehydrogenation on K/C at about 500 °C in accordance with an embodiment of the invention. The reaction conditions of propane dehydrogenation reactions include 5% C3H8 in N2 with about 100 mg 30 wt.% K/C. Total flow rate is about 10 mi min'1. Temperature is about 500 °C. FIG. 24A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). CsHe selectivity firstly increases to about 75% in about 120 minutes and then decreases to about 43% after about 650 minutes. FIG. 24B shows propylene production rate. Deactivation can be observed. Production rate of CaHe firstly increases to about 1.4 mmol gcat -1 h -1 and then decreases to about 0.1 mmol gcaf1 h"1 along the reaction time. FIG. 24C shows the conversion percentage of propane vs time, FIG. 24D shows the percentage of carbon balance.
[00101] FIGs. 25A - 25D illustrate conversion and product formation rates during propane dehydrogenation on K/C at about 400 °C in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% C3H3 in N2 with about 100 mg 30 wt.% K/C. Total flow rate is about 10 ml min 1. Temperature is about 400 °C. FIG. 25A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At the beginning of the reaction, CFU may be the main product. CsHe selectivity increases rapidly from 9% to 91 % in 30 min and then keeps stable. FIG. 24B shows propylene production rate. Production rate of CsHe gradually decreases from 0.3 to 0.1 mmol gcat"1 IT1 along the reaction time. FIG. 24C shows the conversion percentage of propane vs time. FIG. 24D shows the percentage of carbon balance.
[00102] In many embodiments, 20 wt.%KH/C and 30 wt.% KH/C may have similar selectivity during PDH with that on 30 wt.% K/C at about 400 °C. Several embodiments provide K/C and KH/C may become amorphous after PDH processes. Several embodiments provide that CsHe production rate on KH/C may be higher than on K/C under same reaction conditions. FIGs. 26A - 26D illustrate conversion and product yields during propane dehydrogenation on 30wt.% KH/C at about 400 °C in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% CsHs in N2 with about 100 mg 30 wt.% KH/C. Total flow rate is about 10 ml min-1. Temperature is about 400 °C. FIG. 26A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At the beginning of the reaction, CH4 may be the main product. CsHs selectivity increases rapidly from 9% to 91 % in 30 min and then keeps stable, similar to K/C. FIG. 28B shows propylene production rate. Deactivation may be observed. Production rate of CsHe firstly increases to about 0.5 mmol gcat -1 h -1 and then decreases to about 0.3 mmol gcat -1 h -1 after about 1300 min. FIG. 26C shows the conversion percentage of propane vs time. FIG. 28D shows the percentage of carbon balance. [00103] Some embodiments provide that CsHe production rate on 20 wt.% KH/C may be comparable to 30 wt.% KH/C under same reaction conditions. FIGs. 27A - 27D illustrate conversion and product yields during propane dehydrogenation on 2Qwt.% KH/C at about 400 X in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% CsHs in Nb with about 100 mg 20 wt.% KH/C. Total flow rate is about 10 ml min'1. Temperature is about 400 °C. FIG, 27A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At the beginning of the reaction, CH4 may be the main product. C3H6 selectivity increases rapidly to about 94%, similar to 30 wt% KH/C. FIG. 27B shows propylene production rate. Production rate of C3H6 firstly increases to about 0.5 mmol gcat -1 h -1 and then decreases to about 0.1 mmol gcat -1 h -1 after about 2000 min. FIG. 27C shows the conversion percentage of propane vs time. FIG. 27D shows the percentage of carbon balance.
[00104] F!Gs. 28A - 28D illustrate conversion and product formation rates during propane dehydrogenation on 1Gwt.% KH/C at about 400 X in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% C3H8 in N2 with about 100 mg 10 wt.% KH/C. Total flow rate is about 10 ml min'1. Temperature is about 400 X. FIG. 28A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). Being different from other high loading samples, high conversion of C3H8 and high selectivity to CH4 may not be observed on 1Qwt.% KH/C at the beginning of the reaction, FIG. 28B shows propylene production rate. Deactivation may be observed. C3H6 selectivity may keep at about 90% in 400 min, after which gradually decreases to about 84% in 700 min. FIG. 28C shows the conversion percentage of propane vs time. FIG. 28D shows the percentage of carbon balance.
[00106] Many embodiments provide PDH with bare carbon support. Several embodiments provide that at about 400 X, bare carbon support may show negligible activity (about 0.01 mmol gcat -1 h -1 of CsHe production ) for PDH. Selectivity to CsHe may decrease from about 91% to about 68% in 600 min, accompanied by the increasing reaction rate of CsHs cracking. Some embodiments provide that at about 500 X, C3 H6 selectivity may be lower (ca, 50%). FIGs. 29A - 29D illustrate conversion and product yields during propane dehydrogenation on carbon at about 400 °C in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% C3H6 in ISh with about 70 mg carbon. Total flow rate is about 10 ml min -1. Temperature is about 400 °C. FIG. 29A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At 400 °C, bare carbon support shows an initial CsHe selectivity of about 91%, which gradually decreases to about 68% after 600 min. FIG. 29B shows propylene production rate. Production rate of C3H6 is slow at about 0.01 mmol gcat -1 h -1. FIG. 29C shows the conversion percentage of propane vs time. FIG. 29D shows the percentage of carbon balance.
[00106] FIGs. 30A - 30D illustrate conversion and product formation rates during propane dehydrogenation on carbon at about 500 °C in accordance with an embodiment of the invention. The reaction conditions of PDH include 5% CaHs in N2 with about 70 mg carbon. Total flow rate is about 10 mi min-1. Temperature is about 500 °C. FIG. 30A shows propane dehydrogenation product selectivity of propylene (inverted triangle), ethane (circle), ethylene (triangle), and methane (diamond). At 500 °C, bare carbon support shows lower selectivity (ca. 50%) to C3H6. Cracking of C3He to CH4 and C2H4 may be the main side reaction, which can compete with PDH. FIG. 30B shows propylene production rate. FIG. 30C shows the conversion percentage of propane vs time. FIG. 30D shows the percentage of carbon balance.
[00107] While various processes for dehydrogenation of propane using alkali metal and alkali metal hydrides are described above with reference to FIG. 24A - FIG, 30D, any variety of processes that utilize alkali metal and alkali metal hydrides can be utilized in the dehydrogenation processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention. For the purposes of illustrates a specific example of hydrogenation with alkali metal and alkali metal hydrides in accordance with various embodiments of the invention are discussed further below.
Catalytic Hydrogenation on Alkali Metal Hydrides [00108] In a number of embodiments, KH/C can participate in catalytic hydrogenation processes and provide hydrogen to compounds including (but not limited to) aikynes and unsubstituted phenyl rings. Several embodiments provide that KH/C can cleave C-C bonds during hydrogenation processes. Certain embodiments provide KH/C can convert aikynes to olefins with high selectivity, that is, without forming large amounts of alkanes. In some embodiments, KH/C can catalyze hydrogenation of unsubstituted phenyl rings including (but not limited to) biphenyl. Certain embodiments provide that phenyicyclohexane can be a secondary product formed via hydrogenation of biphenyl. Several embodiments provide that the subsequent hydrogenation of phenyicyclohexane to bicyclohexane on KH/C can proceed under a higher pressure of hydrogen,
[00109] Many embodiments provide that phenyicyclohexane can be a secondary product formed via hydrogenation of biphenyl. FIG. 31 illustrates a reaction scheme of hydrogenation of biphenyl to phenyicyclohexane in accordance with an embodiment of the invention. By using biphenyl as the substrate, the hydrogenation of biphenyl to phenyicyclohexane on the KH/C is catalytic with turnover numbers (TON) of up to 23. Several embodiments provide that phenyicyclohexane may be a hydrogenation product independent on the stoichiometric ratios of biphenyl to KH used. In some embodiments, phenyicyclohexane may not form on a bare carbon support. With the absence of H2 and using about 2,3:1 molar ratio of KH/C to biphenyl, about 3% yield of phenyicyclohexane can be obtained. Table 16 lists catalytic hydrogenation of biphenyl using KH/C. The catalytic hydrogenation reactions use mesitylene as a solvent, reaction temperature at about 165 °C, under about 10 bar Ar or about 10 bar H2, with KH/C. The ratio of KH/C is about 0.023 to about 0.37 equivalent per C-H bond. Turnover number (TON) is calculated based on the mol of hydrogenated C=C bonds per mol of KH in KH/C.
Table 16, Catalytic hydrogenation of biphenyl using KH/C.
Figure imgf000045_0001
Figure imgf000046_0001
[00110] Several embodiments provide that the subsequent hydrogenation of phenylcyclohexane to bicyclohexane can proceed at a higher pressure of hydrogen. FIG. 32 illustrates a reaction scheme of hydrogenation of phenylcyclohexane to bicyclohexane in accordance with an embodiment of the invention. At a pressure of about 100 bar of H2, the yield of bicyclohexane may be about 3%, likely because of the steric effect of the cydohexyi group in phenylcyclohexane. Table 17 lists hydrogenation of phenylcyclohexane using KH/C. The catalytic hydrogenation reactions use mesitylene as a solvent, reaction temperature from about 165 °C to about 200 °C, reaction time of about 20 hours, under about 10 bar or about 100 bar H2, with KH/C. The ratio of KH/C is about 0.37 equivalent per C-H bond. Turnover number (TON) is calculated based on the mol of hydrogenated C^C bonds per mol of KH in KH/C,
Table 17. Hydrogenation of phenylcyclohexane using KH/C.
Figure imgf000046_0002
[00111] Selective hydrogenation of carbon triple bond to carbon double bond can be a key step in the synthesis of many important compounds, for instance, vitamins. Many embodiments provide that KH/C can hydrogenate alkyne to alkene. In some embodiments, KH/C act as a catalyst in the hydrogenation of phenyiacetylene substrate. FIG. 33 illustrates a hydrogenation scheme of phenyiacetylene in accordance with an embodiment of the invention, FIG. 33 shows that the target semihydrogenation product styrene can be a major product of phenyiacetylene hydrogenation. Carbon coupling products including dimers and trimers may also form. Table 18 lists various reaction conditions of phenyiacetylene hydrogenation reactions. The solvent used in all reactions is mesityiene. The molar ratio between KH and phenyiacetylene is about 1 :10. The selectivity of styrene can be up to about 86% (at about 33% conversion of phenyiacetylene, Table 6 entry 1 ).
Table 18. Catalytic hydrogenation of phenyiacetylene.
Figure imgf000047_0001
[00112] While various processes for catalytic hydrogenation of organic molecules using alkali metal hydrides are described above with reference to FIG, 31 - FIG. 33, any variety of processes that utilize alkali metal hydrides can be utilized in the hydrogenation processes as appropriate to the requirements of specific applications in accordance with various embodiments of the invention.
EXEMPLARY EMBODIMENTS
[00113] Although specific embodiments of systems and methods are discussed in the following sections, it will be understood that these embodiments are provided as exemplary and are not intended to be limiting.
Example 1: KH/C Formation
[00114] Many embodiments provide KH/C can be prepared by heating at about 110 °C metallic potassium mixed with a carbon support (graphite, surface area about 500 m2 g~1) under about 10 bar of H2 for about 10 hours. The loading of K on KH/C is about 30.1 wt% according to inductively coupled plasma optical emission spectroscopy (ICP-OES), which is close to the nominal loading of 30 wt%. The content of various transition metals (Co, Fe, Cu, Ni, Mo, V, Mn, Cr, Cd, In, Ag, Pd, Pb, Pt, Ru, and Zn) in KH/C is below the detection limit (less than about 1 ppm) of the ICP-OES. X-ray diffraction (XRD) pattern of KH/C contains peaks attributed to graphite (at about 28°, 43° and 54°) and to potassium hydride (at about 27°, 31°, 45°, 53° and 56°), consistent with the oxidation of metallic K by H2. The crystallite size of KH in KH/C is about 40 nm. Temperature-programmed desorption (TPD) can be performed to quantify the amount of KH in KH/C. Three peaks corresponding to the release of H2, at about 171 , 327 and 400 °C, can be observed. The quantity of H2 released from KH/C during the TPD experiment under an Ar flow is about 4.5 mmol H 2 gKH/c\-1 which is higher than the quantity of H2 expected from the KH loading by ICP-OES (3.8 mmol H2 gKH/c -1). This suggests that KH/C contains additional chemisorbed H2. A reference K/C material can be prepared as described above for KH/C except that an Ar atmosphere is used instead of H2. This K/C material has a K loading of about 28.9 wt% according to ICP-OES, and is amorphous by XRD.
[00115] KH/C can be prepared by a melt impregnation method. The carbon support (graphene nanoplateiets with a BET surface area of ca. 500 m2 g”1) can be pre-treated in a N2 flow (30 ml min-1) at about 550 °C for about 6 hours and then stored in a Na-filled glovebox. In the glovebox, about 150 mg of metallic potassium and about 350 mg of the pre-treated carbon support can be physically mixed and placed into an autoclave with a glass liner. Then the autoclave may be sealed, brought out from the glovebox and connected to a high pressure H2 line. The line can be purged (5 times with 10 bar of H2), the autoclave pressurized to about 10 bar of H2, heated to about 110 °C (ramping rate at 5 °C min-1) and hold at this temperature for about 10 hours. After cooling down, the solid material in the autoclave can be collected under the glovebox atmosphere and carefully mixed by using mortar and pestle. The K/C material can be prepared in the same manner as KH/C except that the autoclave is pressurized with 10 bar of Ar instead of H2. A postdecomposition sample of KH/C can be prepared by treating about 150 mg of fresh KH/C in 10 ml of mesitylene in an autoclave under 10 bar Ar (165 °C, 20 hours). After this time, the material may be dried under vacuum on a Scbienk line at room temperature and handled without exposure to air.
Example 2: Desulfurization of dibenzothiophene and its derivatives [00116] Several embodiments provide desulfurization procedures of DBT and its derivatives. In a Nte-filied glovebox, a known amount of a solid material (KH/C, K/C, commercial KH or KHMDS, typically 12-92 mg, 0.09-0.71 mmol K) and a known volume of about 0.03 M mesitylene solution of a substrate (typically, 5-10 ml, 0.15-0.30 mmol) can be added to a glass liner. This gives molar ratios of KH or K to S of the substrate ranging from about 0.6:1 to 2.3:1. The autoclave can be sealed, brought out from the glovebox and connected to a high pressure line of Ar or H2. The line can be purged (5 times with 10 bar of Ar or H2) and the autoclave can be pressurized to a set pressure of Ar or H2 and heated to desired temperature (ramping rate at 5 °C min-1) with mechanical stirring at about 500 rpm. After the test, the reaction mixture can open in air, filtered (filter paper) and the supernatant collected and analyzed by GC-MS.
Example 3: Desulfurization of 2-phenylthiophenol [00117] Some embodiments provide desulfurization of 2-phenylthiopheno! on KH/C. The desulfurization can be performed following the same procedure for DS of dibenzothiophene in Example 2. After reaction, the reaction mixture can be treated in two ways: 1 ) the reaction mixture can be filtered through a filter paper and the supernatant analyzed by GC-MS, or 2) 0.3 ml of isopropanol can be added to the reaction mixture at room temperature and stirred for about 3 hours. Then this reaction mixture filtered through a filter paper and the supernatant analyzed by GC-MS.
Example 4: Desulfurization of di-n-octyl sulfide and diphenyl sulfide [00118] Many embodiments provide desulfurization of di-n-octyl sulfide and diphenyl sulfide on KH/C. KH/C (48 mg, 0.35 mmol K) and 5 ml of solvent (cyclohexane or mesityiene) can be added to a glass liner in a Nfe-fil!ed glovebox. The autoclave can be brought out from the glovebox, 45 pi (0,15 mmol) of di-/?-octyl sulfide or 25 pi (0,15 mmol) of diphenyl sulfide can be quickly injected to the liner and the autoclave sealed immediately. The autoclave can be then filled with Ar or H2 and experiments run as described above for the desulfurization of dibenzothiophene.
Example 5: Desulfurization of dihenzothiophene-sulfone and polyphenylene sulfide [00119] Several embodiments provide desulfurization procedures of dibenzothiophene- sulfone and polyphenylene sulfide KH/C. A known amount of KH/C (typically, 46-118 mg, 0.35-0.91 mmol K), the solid substrate and 5 ml mesityiene, toluene or n~ octane can be added to a glass liner in the glovebox. The molar ratio of KH to sulfur in the reaction mixture may range from 2.3:1 to 6:1. Experiments run as described in Example 2 for desulfurization of dibenzothiophene. After the tests, the reaction mixture can be opened in air, filtered (filter paper) and the supernatant collected and analyzed by GC-MS. Conversion of dibenzothiophene sulfone can be determined by 1H NMR spectroscopy. The reaction mixture after DS of dibenzothiophene-sulfone can be filtered through a filter paper and the supernatant can be collected. The supernatant can be dried under vacuum using a Schienk line at room temperature. Then precipitate can be dissolved in 400 pL CDCIs (containing 0.01 M 1 ,3,5-trimethoxybenzene as an internal standard). The CDCta solution can be used for NMR measurement.
Example 6: Hydrogenation tests
[00120] Many embodiments provide that the hydrogenation procedures are similar as that for the desulfurization of dibenzothiophene. In one experiment, a mixture of about 46 mg KH/C (0.35 mmol K) and 5 ml of a 0.03-0.70 M solution of biphenyl, pbenyicyclohexane or phenylacety!ene In mesitylene can be used.
Example 7: Deoxygenation of dibenzofuran
[00121] Several embodiments provide that experimental procedures for the desulfurization of dibenzothiophene can be used for deoxygenation of dibenzofuran. In one experiment, a mixture of KH/C (46 mg, 0.35 mmol K) and 5 ml of solution containing 0.03 M dibenzofuran (0.15 mmol of dibenzofuran) in mesitylene can be used. After reaction, the reaction mixture can be treated In two ways: 1) the reaction mixture can be filtered through a filter paper and the supernatant analyzed by GC-MS; 2) 0.3 ml of isopropanol can be added to the reaction mixture at room temperature and stirred for 3 h. Then this reaction mixture can be filtered through a filter paper and the supernatant analyzed by GC-MS.
Example 8: Denitrogenation of 9-phenyl carbazole
[00122] Several embodiments provide that experimental procedures for the desulfurization of dibenzothiophene can be used for denitrogenation of 9-phenyl carbazole. In one experiment, a mixture of 46-65 mg (0.35-0.50 mmol K) of KH/C and 5 ml of a 0.03 M solution of 9~phenyl carbazole in mesitylene (0.15 mmol) can be used.
Example 9: Ultra-deep desulfurization tests
[00123] Many embodiment provide procedures for ultra-deep desulfurization processes. Solutions of 4,6-DMDBT in mesitylene with a concentration of 1000 ppm (a), 100 ppm (b) or 10 ppm (c) can be prepared in a Ns-filled glovebox. Solution (a) can be prepared by dissolving 284 mg (1 .25 mmol) of 4,8-DMDBT in 46 ml mesitylene. Solutions (b) and (c) can be prepared, respectively, by a 10-fold and a 100-fold dilution of solution a with mesitylene. In the Na-filled glovebox, a known amount of KH/C and a known volume of 4,8-DMDBT solution (a, b, or c) can be added to a glass liner of the autoclave. More specifically, 9-218 mg of KH/C (0.07-1.86 mmol K) can be mixed with 20 mi of the substrate solution to reach about 3:1 or 12:1 molar ratio of KH : 4,6-DMDBT. The autoclave can be sealed, brought out from the glovebox and connected to a high pressure Ar line. The line can be purged and the autoclave can be pressurized to 10 bar of Ar. Desulfurization experiments can run at 185 °C for 20 h under mechanical stirring (500 rpm). After this time, the autoclave can be depressurized and the reaction mixture filtered three times to remove the solid material (filter paper). The supernatant can be collected and used to determine the quantity of sulfur and potassium after the reaction by iCP- OES.
Example 10: Deuteration experiments
[00124] Deuteration experiments can be conducted by using toiuene-ds or benzene-de as the solvent in accordance with some embodiments. The experimental procedure is similar as the desulfurization of dibenzothiophene or deoxygenation of dibenzofuran. In one experiment, KH/C (28 mg, 0.21 mmol KH), DBT (18.6 mg, 0.09 mmol) or biphenyl (13.9 mg, 0.09 mmol) or dibenzofuran (15,1 mg, 0.09 mmol) can be added to 3 ml of toluene-de or benzene-de. The reactions can be performed at 50 or 185 °C in 10 bar of Ar for 3-20 h. Identification of products and their mass number analyses can be performed using the gas chromatography mass spectrometer (GC-MS).
Example 11: Propane dehydrogenation tests
[0093] The performance of propane dehydrogenation on KH/C, K/C or bare carbon support can be evaluated using a fixed bed reactor. Typicaily, 100 mg of solid material can be loaded between two plugs of quartz wool into a fixed-bed reactor in a ISb-fiiled glovebox. The reactor can be sealed, brought out from the glovebox and connected to a gas line. The gas line can be purged by a flow of N2 and then a mixture of 5% C3H3 in N2 (total flow rate of 10 ml min-1) can be flown Into the reactor. The reactor can be heated to the desired reaction temperature (400 or 500 °C, 10 °C min-1). The off-gas composition can be analysed using a Clarus 480 gas chromatograph (PerkinEimer) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD). The chromatograms can be acquired every 14 minutes.
DOCTRINE OF EQUIVALENTS
[00125] As can be inferred from the above discussion, the above-mentioned concepts can be implemented in a variety of arrangements in accordance with embodiments of the invention. Accordingly, although the present invention has been described in certain specific aspects, many additional modifications and variations would be apparent to those skilled in the art. It is therefore to be understood that the present invention may be practiced otherwise than specifically described. Thus, embodiments of the present invention should be considered in ail respects as illustrative and not restrictive.
[00126] As used herein, the singular terms "a," "an,” and "the" may include plural referents unless the context clearly dictates otherwise. Reference to an object in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more."
[00127] As used herein, the terms "substantially" and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. When used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ± 10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1 %, less than or equal to ±0,5%, less than or equal to ±0.1 %, or less than or equal to ±0.05%.
[00128] Additionally, amounts, ratios, and other numerical values may sometimes be presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicit!y specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a ratio in the range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual ratios such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth.

Claims

WHAT IS CLAIMED IS:
1. A system for desulfurization, denitrogenation, deoxygenation, dehydrogenation, and hydrogenation comprising: at least one alkali metal hydride of a formula MaHb; and a carbon substrate; wherein M is selected from the group consisting of lithium, sodium, and potassium, and a molar ratio a/b between M and H is: 0 < a/b < 1 ; wherein the at least one alkali metal hydride is supported on the carbon substrate; and wherein the system reductively cleaves at least one C-X bond in an organic substrate, wherein X is selected from the group consisting of S, N, 0, H, and C.
2. The system of claim 1 , wherein the system is free of transition metal and free of silane.
3. The system of claim 1 , wherein the system reductively cleaves at least one C- S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound.
4. The system of claim 1 , wherein the system reductively cleaves at least one C-
S bond in a S-containing organic substrate selected from the group consisting of dibenzothiophene, 4,6-dimethyldibenzothiophene, 4,6- diethyldibenzothiophene, 4-methyldibenzothiophene, dibenzothiophene sulfone, diphenyl sulfide, 2-phenylthiophenol, polyphenylene sulfide, and aliphatic di-n~octyl suifide.
5. The system of claim 1, wherein the desulfurization occurs at a temperature between 50 °C and 165 °C.
6. The system of claim 1 , wherein the system reduetively cleaves at least one C~ N bond in a N-coniaining heterocyclic compound.
7. The system of claim 8, wherein the N-containing heterocyclic compound is 9- phenyi-carbazole.
8. The system of claim 1 , wherein the system reduetively cleaves at least one C- 0 bond in a O-containing heterocyclic compound.
9. The system of claim 8, wherein the O-containing heterocyclic compound is dibenzofuran.
10. The system of claim 1 , wherein the system reduetively cleaves at least one C- H bond and removes at least one H In propane.
11. The system of claim 10, wherein the alkali metal is potassium and potassium hydride on carbon decomposes to potassium on carbon during propane dehydrogenation.
12. The system of claim 11 , wherein the potassium hydride on carbon has a weight percentage between 20% and 30%.
13. The system of claim 1 , wherein the at least one alkali metal hydride is potassium hydride and the carbon substrate is graphite.
14. The system of claim 1 , further comprising an organic solvent.
15. The system of claim 14, wherein the organic solvent is selected from the group consisting of mesityiene, cyclohexane, toluene, and n-octane.
16. The system of claim 1 , wherein the desulfurization, denitrogenation, and deoxygenation occur under hydrogen gas or an inert gas selected from the group consisting of argon, nitrogen, and helium.
17. The system of claim 1 , wherein the dehydrogenation occurs under an inert gas selected from the group consisting of argon, nitrogen, and helium,
18. The system of claim 1 , wherein the system cleaves at least one C-C bond in aromatic heterocyclic compounds and catalytically hydrogenizes at least one unsubstituted phenyl ring,
19. The system of claim 18, wherein the unsubstituted phenyl ring is biphenyl,
20. The system of claim 1 , wherein the system cleaves at least one C-C bond and catalytically hydrogenates at least one carbon triple bond in an a!kyne to form at least one carbon double bond in an olefin.
21 .The system of claim 20, wherein the alkyne is phenyiacetylene.
22, The system of claim 1 , wherein the hydrogenation occurs under hydrogen gas.
23, A system for dehydrogenation comprising: at least one alkali metal; and a carbon substrate; wherein the at least one alkali metal is selected from the group consisting of lithium, sodium, and potassium; wherein the carbon substrate supports the at least one alkali metal; and wherein the system reductively cleaves at least one OX bond in an organic substrate, wherein X is H or C,
24, The system of claim 23, wherein the organic substrate is propane.
25. The system of claim 23, wherein a dehydrogenation temperature is at least 400 °C.
26. The system of claim 23, wherein the dehydrogenation occurs under an inert gas selected from the group consisting of nitrogen, helium, and argon.
27. The system of claim 23, wherein the alkali metal is potassium and the carbon substrate is graphite.
28. The system of claim 27, wherein the potassium on the carbon substrate has a weight percentage between 20% and 30%.
29. A system for desulfurization comprising a molecular compound comprising at least one alkali metal selected from the group consisting of lithium, sodium, and potassium.
30. The system of claim 29, wherein the system reductively cleaves at least one C- S bond in a S-containing aromatic heterocyclic compound or a S-containing aliphatic compound.
31. The system of claim 29, wherein the molecular compound is potassium bis(trimethylsilyl)amide.
32. The system of claim 29, wherein the system if free of silane and free of transition metal.
33. The system of claim 31 , further comprising an organic solvent, wherein the organic solvent is selected from the group consisting of mesity!ene, toluene, and n-octane.
34. The system of claim 31 , wherein the system reductiveiy cleaves at least one C- S bond in a S-containing organic substrate selected from the group consisting of dibenzothiophene, 4,6-dimethyldibenzothiophene, and 4,6- d!ethyld!benzothiophene.
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