Classifications

• • 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
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/041—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41
  • B01J29/045—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
• • 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
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/24—Chromium, molybdenum or tungsten
• • 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
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/74—Iron group metals
• • 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
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
• • 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
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
  • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
  • B01J29/0316—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing iron group metals, noble metals or copper
  • B01J29/0333—Iron group metals or copper
• • 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
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
  • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
  • B01J29/0341—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
• • 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
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/041—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41
  • B01J29/042—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41 containing iron group metals, noble metals or copper
  • B01J29/044—Iron group metals or copper
• • 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
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/64—Pore diameter
  • B01J35/647—2-50 nm
• • 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
  • C10G45/12—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 containing crystalline alumino-silicates, e.g. molecular sieves
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/10—After treatment, characterised by the effect to be obtained
  • B01J2229/20—After treatment, characterised by the effect to be obtained to introduce other elements in the catalyst composition comprising the molecular sieve, but not specially in or on the molecular sieve itself
• • 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
  • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
  • B01J2229/30—After treatment, characterised by the means used
  • B01J2229/42—Addition of matrix or binder particles
• • 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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/20—Sulfiding

Definitions

• the present invention relates to a catalyst and process for selectively hydrodesulfurizing naphtha feedstreams using a catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material.
• Gasoline comprises naphtha boiling-range hydrocarbons ("naphtha") obtained from natural and/or synthetic sources.
• Naphtha especially naphtha obtained from a cracking process, such as fluidized catalytic cracking and coking, typically contains undesirable sulfur species.
• naphtha also can contain valuable olefins which contribute to the octane number of the resulting gasoline, and it is, consequently, highly desirable not to saturate them to lower octane paraffins during processing.
• Continuing regulatory pressure to lower the amount of sulfur present in naphtha has resulted in a continuing need for catalysts having ever improved desulfurization properties.
• the invention relates to a selective hydrodesulfurization catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material and bound with a silica binder derived from silicone resin.
• the invention in another embodiment, relates to a selective hydrodesulfurization process, comprising: contacting a naphtha feedstream containing sulfur and olefin with a catalytically effective amount of a catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material under selective catalytic hydrodesulfurization conditions.
• Yet another embodiment of the invention relates to a selective hydrodesulfurization process, comprising: contacting a naphtha feedstream containing sulfur and olefin with a catalytically effective amount of a catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material and silica binder derived from silicone resin under selective catalytic hydrodesulfurizing conditions.
• the invention relates to a selective hydrodesulfurization catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material, the selective hydrodesulfurization catalyst being made by a process comprising: (a) combining the low acidity, ordered mesoporous support material with silicone resin to form a mixture of mesoporous support material and silicone resin,
• step (b) calcining the mixture from step (a) to convert silicone resin to silica binder
• step (c) impregnating the calcined low acidity, ordered mesoporous support material from step (b) with an aqueous precursor containing at least one metal to form a metal-impregnated, low acidity, ordered mesoporous support material, and
• step (d) heating the calcined metal-impregnated, low acidity, ordered mesoporous support material from step (c) at a drying temperature and drying pressure and for a drying time to remove water and form a dried, metal-impregnated, low acidity, ordered mesoporous support material.
• the combining of ordered mesoporous support material with silicone resin is free of added organic solvent.
• the process further comprises sulfiding the metal- impregnated low acidity, ordered mesoporous support under sulfiding conditions for a sulfiding time to form the selective hydrodesulfurization catalyst.
• the figure is a graph showing the rate ratio of hydrodesulfurization/olefin saturation vs. amount of hydrodesulfurization for two catalysts having different support acidities. - A -
• the invention relates to (I) a selective hydrodesulfurization catalyst, (II) a selective hydrodesulfurization process, and (III) method for making a selective hydrodesulfurization catalyst.
• the invention relates to a selective hydrodesulfurization catalyst comprising at least one catalytic metal supported on a low acidity, ordered mesoporous support material and bound with a silica binder.
• a selective hydrodesulfurization catalyst comprising at least one catalytic metal supported on a low acidity, ordered mesoporous support material and bound with a silica binder.
• the terms "macropores” and “mesopores” are as defined in Pure Appl. Chem., 45 (1976), 79, namely as pores whose diameter is above 50 nm (macropores) or whose diameter is from 2 nm and 50 nm (mesopores).
• the catalytic metal or metals can be Group VIA and non-noble metal Group VIIIA metals. The Groups are given in the Periodic Table of the Elements by Sargent- Welch Scientific Company, No.
• the metal is selected from at least one of Mo, Co, Ni, Fe, W. More than one such metal can be used.
• Total metal loading on the catalyst may range from 4 to 40 wt.% metals, based on catalyst, preferably 10 to 30 wt.%.
• the support comprises one or more low acidity, ordered mesoporous materials, such as molecular sieve.
• molecular sieve refers to ordered structures having pore sizes suitable for adsorbing molecules and that are capable of separating components of a mixture on the basis of molecular size and shape differences.
• the low acidity, ordered mesoporous materials may be crystalline, that is, having sufficient order to provide a diffraction pattern such as, for example, by X-ray, electron or neutron diffraction, following calcination, with at least one peak.
• the term "low acidity" is used herein in the sense of a 2-methyl-2 pentene reaction test and the resulting rate ratio, as described in Kramer and McVicker, Accounts of Chemical Research, 19, 78 (1986), and U.S. Patent No. 5,420,092.
• This scale for evaluating the acidity of materials is based on the isomerization of 2-methyl-2-pentene (2MP2).
• the material to be evaluated is contacted with 2MP2 at a fixed temperature, typically in the range of 200 0 C to 25O 0 C.
• the formation rates and rate ratios of the product hexene isomers of this test reaction reflect the acid site concentration and strength of the catalyst respectively.
• the product hexene isomers formed include (cis/trans)4-methylpent- 2-ene (4MP2), (cis/trans)3-methyl ⁇ ent-2-ene (3MP2), and 2,3 dimethylbute-2-ene (2,3 DMB2).
• 4MP2 requires only a double bond shift, a reaction occurring on weak acid sites.
• 3MP2 requires a methyl group shift (i.e., stronger acidity than double bond shift), whereas 2,3DMB2 requires even stronger acidity to produce a second methyl branch.
• differences in 3MP2 rates normalized with respect to surface area reflect the density of acid sites possessing strengths sufficient to catalyze the skeletal isomerization.
• Rate Ratio is expressed as the rate of (cis/trans)3-methylpent-2-ene (3MP2) over (cis/trans)4-methylpent-2-ene (4MP2).
• the use of the Rate Ratio in lieu of individual conversion rates, beneficially normalizes differences in acid site populations.
• rate ratio of 3MP2 to 4MP2 provides a useful scale of acidity and forms the basis of the definition of "low acidity" as that term is used herein.
• the rate ratio of 3MP2 to 4MP2 is "low acidity" at a ratio of 3.85 or less, preferably 3.25 or less, more preferably 3.00 or less. It should be noted that that these low acidity materials will have an Alpha value of 1.
• the Alpha test is described in U.S. Patent No. 3,354,078. However, the Alpha test is not as sensitive for evaluating acidity as the acidity scale based on the isomerization of 2MP2. Hence two different materials may have an Alpha value of 1, but may or may not meet the definition of "low acidity" as defined herein. Controlling the acidity of the support provides a means to hydrodesulfurize a naphtha feedstream while minimizing saturation of desirable olefins.
• the low acidity, ordered mesoporous material contains silica and alumina
• a high silica material is desired for low acidity.
• the silica to alumina molar ratio is preferably at least 100, more preferably at least 200, and most preferably at least 300.
• Support porosity generally ranges from 20 to 75% by volume, or, alternatively, from 20% to 60% by volume.
• Support surface areas generally ranges upwards from 20 m 2 /g, or alternatively, from 20 m 2 /g to at least 200 m 2 /g, or 100 m 2 /g to at least 400 m 2 /g.
• Ordered mesoporous materials can accommodate surface areas up to 1000 m 2 /g.
• the ordered mesoporous materials are of low acidity, inorganic, porous, non-layered, molecular sieve materials which, in their calcined forms, exhibit an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18 Angstrom Units (A). They also have a benzene adsorption capacity of greater than 15 grams of benzene per 100 grams of the material at 50 torr and 25 0 C. Suitable ordered mesoporous materials include those synthesized using amphophilic compounds as directing agents. Examples of such materials are described in U.S. Patent No. 5,250,282.
• amphiphilic compounds are also disclosed in Winsor, Chemical Reviews, 68(1), 1968.
• Other suitable ordered mesoporous materials are disclosed in "Review of Ordered Mesoporous Materials," U. Ciesla and F. Schuth, Microporous and Mesoporous Materials, 27, (1999), 131- 49.
• Suitable mesoporous materials include, by way of example, materials designated as SBA (Santa Barbara) such as SBA-2, SBA- 15 and SBA- 16, materials designated as FSM (Folding Sheet Mechanism) such as FSM- 16 and KSW-2, materials designated as MSU (Michigan State) such as MSU-S and MSU-X, materials designated as TMS or Transition Metal Sieves, materials designated as FMMS or functionalized monolayers on mesoporous supports and materials designated as APM or Acid Prepared Mesostructure.
• the support material is characterized by a substantially uniform hexagonal honeycomb microstructure with uniform pores having a cell diameter greater than 2 nm and typically in the range of 2 to 50 nm, preferably 3 to 30 nm, and most preferably from 3 to 20 nm.
• the low acidity, ordered mesoporous materials include the silicate ordered mesoporous materials designated as M41S such as MCM-41, MCM-48 and MCM-50, including mixtures thereof, provided they are of sufficiently low acidity.
• MCM-41 can be synthesized as a metallosilicate with Broensted acid sites by incorporating a tetrahedrally coordinated trivalent element such as Al, Ga, B, or Fe within the silicate framework. Methods of preparation are described in U.S. Patents Nos. 5,098,684, 5,102,643 and 5,837,639.
• MCM-41 is characterized by a microstructure with a uniform, hexagonal arrangement of pores with diameters of at least 2 nm. After calcination, it exhibits an X-ray diffraction pattern with at least one d-spacing greater than 18 A. and a hexagonal electron diffraction pattern that can be indexed with a dioo value of greater than 18 A, which corresponds to the d-spacing of the peak in the X-ray diffraction pattern.
• hexagonal is intended to encompass not only materials that exhibit mathematically perfect hexagonal symmetry within the limits of experimental measurement, but also those with significant observable deviations from that ideal state.
• a working definition as applied to the microstructure of the ordered mesoporous support material would be that most channels in the material would be surrounded by six nearest neighbor channels at roughly the same distance. Defects and imperfections will cause significant numbers of channels to violate this criterion to varying degrees, depending on the quality of the material's preparation. Samples which exhibit as much as +/- 25% random deviation from the average repeat distance between adjacent channels still clearly give images recognizable as hexagonal.
• MCM-41 and similar ordered mesoporous materials can be distinguished from other porous inorganic solids by the regularity of their large open pores, whose pore size more nearly resembles that of amorphous or paracrystalline materials, but whose regular arrangement and uniformity of size (pore size distribution within a single phase of, for example, +/-25%, usually +/- 15% or less of the average pore size of that phase) resemble more those of crystalline framework materials such as zeolites.
• the low acidity, ordered mesoporous material used in the catalyst support has the following composition:
• W is a divalent element, such as a divalent first row transition metal, e.g., manganese, cobalt and iron, and/or magnesium, preferably cobalt
• X is a trivalent element, such as aluminum, boron, iron and/or gallium, preferably aluminum
• Y is a tetravalent element such as silicon and/or germanium, preferably silicon
• Z is a pentavalent element, such as phosphorus
• M is one or more ions, such as, for example, ammonium, Group IA, HA and VIIB ions, usually hydrogen, sodium and/or fluoride ions
• n is the charge of the composition excluding M expressed as oxides
• q is the weighted molar average valence of M
• n/q is the number of moles or mole fraction of M
• a, b, c, and d are mole fractions of W, X,
• the mesoporous material has a composition, on an anhydrous basis, expressed empirically as follows:
• R is the total organic material not included in M as an ion
• r is the coefficient for R, i.e., the number of moles or mole fraction of R.
• the M and R components are associated with the material as a result of their presence during synthesis of the material and are easily removed or, in the case of M, replaced by post-synthesis methods hereinafter more particularly described.
• the original M e.g., ammonium, sodium or chloride
• ions of the as-synthesized material can be replaced, at least in part, by ion exchange with other ions.
• Conventional ion-exchange methods can be used.
• Replacing ions include metal ions, hydrogen ions, hydrogen precursor, e.g., ammonium, ions and mixtures thereof.
• ions include rare earth metals and metals of Groups IA (e.g., K), HA (e.g., Ca), VIIA (e.g., Mn), VIIIA (e.g., Ni), IB (e.g., Cu), HB (e.g., Zn), IIIB (e.g., In), IVB (e.g., Sn), and VIIB (e.g., F) of the Periodic Table of the Elements (Sargent- Welch Co. Cat. No. S- 18806, 1979) and mixtures thereof.
• IA e.g., K
• HA e.g., Ca
• VIIA e.g., Mn
• VIIIA e.g., Ni
• IB e.g., Cu
• HB e.g., Zn
• IIIB e.g., In
• IVB e.g., Sn
• VIIB e.g., F
• the support can further comprise additional materials, particularly additional inorganic materials.
• inorganic materials may be used as binders, or to dilute and therefore control the amount of active mesoporous material present in the support.
• Inorganic diluents can be inert or, optionally, can have a catalytic functionality.
• Suitable inorganic diluent materials include, by way of example, alumina or silica and the like, or precursors to these materials such as Na-silicate and Al-nitrate.
• the particulate inorganic oxides are not acting as binder materials but are primarily acting as bulk diluents although the material may still exert some binding function.
• the binder function can be performed by the particulate silicone resin, a separate binder can be used. In the calcined state of the support, it is believed that the binder function is provided by silica derived from the silicone resin on top of any other binder that may be present. In the uncalcined state (e.g., the dried state), it is believed that the binding, (i.e., the green strength) is in part derived from the resin as is.
• the particulate inorganic materials When used as diluents for supports comprising molecular sieves, the particulate inorganic materials may be present at the desired level to achieve the requisite dilution of molecular sieve.
• the amount of diluent material can be within the range of 10 to 90 wt.%, or 10 to 50 wt.%, or 20 to 50 wt. % of the combined weight of diluent and molecular sieve material in the structure.
• the inorganic material may also or alternatively function as an aid to mass transport into and within the structured body. This can be advantageous when the inorganic material has large pores and high levels of porosity.
• the uncalcined binder material (the silicone resin) itself is not acidic. Thus the addition of silicone binding material should have a dilution function on the total acidity prior to calcination.
• the invention in another embodiment, relates to a selective hydrodesulfurization process. More particularly, the invention relates to selective hydrodesulfurization of a naphtha boiling-range hydrocarbon.
• Naphtha feedstocks suitable for hydrodesulfurization comprise one or more natural and/or synthetic hydrocarbons boiling in the range from 50 0 F to 450 0 F (1O 0 C to 232 0 C), at atmospheric pressure.
• the naphtha feedstock generally contains cracked naphtha which usually comprises fluid catalytic cracking unit naphtha (FCC catalytic naphtha), coker naphtha, hydrocracker naphtha, resid hydrotreater naphtha, debutanized natural gasoline (DNG), and gasoline blending components from other sources wherein a naphtha boiling range stream can be produced.
• the feedstock is selected from FCC catalytic naphtha, coker naphtha, and combinations thereof.
• the naphtha feedstock generally contains not only paraffins, naphthenes, and aromatics, but also unsaturates, such as open-chain and cyclic olefins, dienes, and cyclic hydrocarbons with olefinic side chains.
• the cracked naphtha feedstock generally comprises an overall olefins concentration ranging as high as 60 wt.%, based on feedstock, more typically as high as 50 wt.%, and most typically from 5 wt.% to 40 wt.%.
• the cracked naphtha feedstock can comprise a diene concentration of as much as 15 wt.% 5 but more typically ranges from 0.02 wt.% to 5 wt.% of the feedstock.
• the cracked naphtha feedstock sulfur content will generally range from 0.05 wt.% to 0.7 wt.% and more typically from 0.07 wt.% to 0.5 wt.%, based on the total weight of the feedstock.
• Nitrogen content will generally range from 5 wppm to 500 wppm, and more typically from 20 wppm to 200 wppm.
• Hydrodesulfurization using the selective hydrodesulfurization catalysts can comprise a naphtha feedstock preheating step.
• the chargestock is preheated in feed/effluent heat exchangers prior to entering a furnace for final preheating to a targeted reaction zone inlet temperature.
• the feedstock can be contacted with a hydrogen-containing stream prior to, during, and/or after preheating.
• the hydrogen-containing stream can also be added in the hydrodesulfurization reaction zone.
• the hydrogen stream can be pure hydrogen or can be in admixture with other components found in refinery hydrogen streams. It is preferred that the hydrogen-containing stream have little, if any, hydrogen sulfide.
• the hydrogen stream purity should be at least 50% by volume hydrogen, preferably at least 65% by volume hydrogen, and more preferably at least 75% by volume hydrogen for best results.
• the reaction zone can consist of one or more fixed bed reactors each of which can comprise a plurality of catalyst beds. Since some olefin saturation will take place, and olefin saturation and the desulfurization reaction are generally exothermic, consequently interstage cooling between fixed bed reactors, or between catalyst beds in the same reactor shell, can be employed. A portion of the heat generated from the hydrodesulfurization process can be recovered, and where this heat recovery option is not available, cooling may be performed through cooling utilities such as cooling water or air, or through use of a hydrogen quench stream. In this manner, optimum reaction temperatures can be more easily maintained.
• the hydrodesulfurization process uses a reactor inlet temperature below the dew point of the feedstock so that the naphtha fraction will not be completely vaporized at the reactor inlet.
• the hydrodesulfurization reaction begins when the naphtha feed contacts the catalyst, some of the exothermic heat of reaction is absorbed by the endothermic heat of vaporization, thus achieving 100% vaporization within the bed (dry point operation).
• the overall temperature rise across the reactor is moderated, thus reducing the overall extent of olefin hydrogenation with only small reductions in hydrodesulfurization.
• the degree of vaporization is defined by the ratio of the inlet dew point temperature (T DP , R) of the naphtha feedstock to the reactor inlet temperature (T IN , R), where R is the absolute temperature in degrees Rankine.
• the dew point temperatures can be calculated by computer software programs, such as Pro/II, available from Simulation Sciences Inc.
• the T DP /T ⁇ - J ratio should be greater than or equal to 0.990, but less than the ratio at which dry point operation is not achieved within the catalyst bed. That is, the ratio extends up to the point at which the operation stays all mixed phase in the reactor.
• the ratio limit may vary somewhat depending on selected operating conditions.
• hydrodesulfurization of the naphtha feedstocks are performed under the following conditions:
• reaction pressures and hydrogen circulation rates below these ranges can result in higher catalyst deactivation rates resulting in less effective selective hydrotreating. Excessively high reaction pressures increase energy and equipment costs and provide diminishing marginal benefits.
• the selective hydrodesulfurization catalysts are supported catalysts, in which the support comprises a low acidity, ordered mesoporous material.
• Such catalysts can be made by impregnating a low acidity, ordered mesoporous material with the catalytic metal(s).
• Conventional methods in which the catalytic metal is contained in an aqueous precursor can be used.
• Aqueous precursors can further comprise an organic complexing agent, as described in Chem. Soc. Chem. Commun. 22, 1684 (1987).
• impregnation of the hydrodesulfurizing metal or metals on the catalyst support can be performed using incipient wetness techniques. An amount of water to just wet all of the support is determined and added. The aqueous impregnation solutions are added such that the aqueous solution contains the total amount of hydrogenation component metal(s) to be deposited on the given mass of support. When more than one hydrodesulfurizing metal is to be used, impregnation can be performed for each metal separately, including an intervening drying step between impregnations, or as a single co-impregnation step. The saturated support can then be separated, drained, and dried in preparation for calcination.
• impregnation of the hydrodesulfurizing metal or metals is on the calcined low acidity, ordered mesoporous support material which has been mixed with silicone resin. Calcination generally is performed at a temperature of from 480 0 F to 1200 0 F (249 0 C to 649 0 C), or more preferably from 800 0 F to 1100 0 F (427°C to 593 0 C).
• the low acidity, ordered mesoporous supports have relatively low levels of inorganic binder and have been manufactured without the addition of organic solvents, i.e., they are free of added organic solvent.
• present support materials either contain no added organic solvent, or that if amounts of organic solvents are present in the support materials, they are present in such minor amounts that their presence will not adversely affect the integrity of the silica binder formed upon calcination.
• the amount of solvent which any given support material may tolerate is determined by comparing the physical properties, especially the crush strength, of the silica bound support material with and without the organic solvent. It is preferred that no organic solvent be added to the support material. It is preferred to use water instead of added organic solvents in the manufacturing process. [0032] When organic solvents are omitted from the support formulation, calcined supports have higher compressive strength than calcined supports formed using organic solvents.
• Impregnation of the calcined support can be accomplished as described above for the catalyst support.
• Conventional methods can be used to make catalyst supports. Such methods generally include the steps of mixing batch materials, which have as their main constituents particulate inorganic material (and, optionally, binder), blending the mixture, forming or shaping the batch into a green body, drying, and subsequently calcining the green body to form the support.
• forming is undertaken via extrusion or via other methods that require the application of pressure and/or heat such as compression molding.
• Binders when used, can be inorganic, organic, or a combination thereof.
• Organic binders are temporary binders because they can be removed during heat-treating such as calcination, but they may assist in maintaining the green strength of the structured body extrudate after extrusion.
• the green support is free of organic binder, and the formed and calcined support is also free of organic binder residues.
• porosity is also dependent on the firing temperature. The higher the firing temperature, the more dense (less porous) the resulting fired structure. Conventional extrusion procedures and equipment can be used, including the use of extrusion aids.
• the support material is a low acidity, ordered mesoporous support material.
• Ordered mesoporous support materials can be synthesized using amphiphilic compounds, as hereinafter described, and especially high silica/alumina ratio mesoporous materials, especially the high surface area mesoporous aluminosilicate and silicate materials designated as M41S silica materials such as for example MCM-41 and MCM-48.
• Such materials can be made using from a homogeneous formable mixture comprising support material, silicone resin, optional extrusion aid and water.
• the mixture components are combined to form a homogeneous or substantially homogeneous mixture without the addition of organic solvent.
• the dry ingredients are first combined, e.g., dry blended in an intensive mixer, and then water is added in an amount to enable the formation of an extrudable mixture.
• Typical water amounts form a mixture that is at least 20 wt.% solids, or at least 30 wt.% solids, or at least 40 wt.% solids, based on the weight of the mixture.
• Solids typically range from 20 to 70 wt.% solids, or 30 to 70 wt.% solids, based on the weight of the mixture.
• Conventional mixing equipment e.g., mix-muller or high shear mixers, and "noodling dies" can be used.
• some suitable mixture compositions include 25 to 95 wt.% support material, and 5 to 75 wt.% silicone resin.
• Extrusion aids can be added in amounts ranging from 1 to 5 wt.%, or alternatively, 1 to 2 wt.%, or 1.5 wt.% or less.
• the extrudate contains sufficient support material to yield a final calcined support comprising:
• support material in an amount ranging from 40 to 95 parts by weight (wt.%), or alternatively, 70 to 95 wt.%, or 80 to 95 wt.%, and
• silica in an amount ranging from 5 to 60 parts wt.%, or alternatively, 5 to 20 wt.%, or 5 to 10 wt.%, the wt.% being based on the weight of the extrudate.
• silica in an amount ranging from 0.5 to 50 parts by wt.%, or alternatively, 5 to 25 wt.%, or 5 to 20 wt.%, or 5 to 10 wt.% silica.
• Such supports can be made using silicone resin of defined average particle size.
• a silicone resin in this form enables the support material to be extruded without the use of high levels of additional organic or undesirable inorganic binder materials, with the minimal amount necessary of organic extrusion aids and importantly without the use of organic solvents. This enables green extrudates of high strength to be produced.
• This approach also enables support materials to be produced, which have high contents of active catalytic material (90 wt.% or greater) and which have high compressive strengths after calcination.
• the silicone resin of defined average particle size is converted in-siru to a silica binder upon calcination.
• the resultant calcined support material contains a primarily low acidity silica binder, which is highly desirable for many applications especially where the support material comprises ordered mesoporous materials.
• silicone resins can be used.
• the silicone resin is used in particulate form as opposed to an emulsion, or a solution or in the form of flakes.
• the particulate silicone resins of this embodiment have the following properties:
• the particulate silicone resins can have an average particle size of 700 ⁇ m or less, preferably 600 ⁇ m or less. Expressed in terms of a range, the average particle size of the particulate silicone resin can range from 0.01 to 700 ⁇ m or, alternatively, 0.02 to 600 ⁇ m, or 0.1 to 450 ⁇ m. (ii) The particulate silicone resins have a minimum particle size ranging from at least 2 ⁇ m to at least about 25 ⁇ m.
• the particulate silicone resin remains solid at ambient temperature (i.e., room temperature or below the forming temperature used to prepare the support, e.g., below the extrusion or compression molding temperature).
• the particulate silicone resins can have a softening point such that under the selected pressures and temperatures of forming, e.g., extrusion or compression molding, it melts or flows or is able to coalesce.
• the silicone resin can re-solidify on cooling after extrusion or compression molding.
• the particulate silicone resins can have a silicon oxide content of at least 50% by weight and a degree of cross-linking of 1.5 or less or, alternatively, 1.3 or less, or 1.2 or less.
• the particulate silicone resins can have a viscosity of at least about 20 centipoise (60% solids in toluene, though the use of a solvent is optional) or, alternatively, at least about 30 centipoise, or at least about 50 centipoise.
• the particulate silicone resins have a weight average molecular weight within the range of about 1000 to 10000 or, alternatively, about 2000 to 7000, or about 2000 to 4000.
• the particulate silicone resins have a silanol content of at least about 3 wt.% or, alternatively, at least about 5 wt.%
• the silicone resin can be a single silicone resin or a combination of silicone resins, which meet the above criteria.
• Silicone resins include polysiloxanes containing a repeating silicon-oxygen backbone and organic groups attached to a proportion of the silicon atoms by silicon-carbon bonds, including linear, branched and/or cross-linked structures.
• Silane monomers are the precursors of silicones and the nomenclature of silicones makes use of the letters M, D, T and Q to represent monofunctional, difunctional, trifunctional and quadrifunctional monomer units.
• Primes, e.g., D' are used to indicate substituents other than methyl. Examples of formulas and their corresponding symbols for silicones are provided in Table 1.
• the silicone resins are the polysiloxanes with alkyl and/or aryl and/or glycol groups.
• the alkyl groups can include 1 to 12 carbons, and more particularly 6 to 10 carbons.
• the resins can be cross-linkable silicones containing reactive silanol groups. Examples of suitable silicone resins are those that originate from methyl hydrogen polysiloxane and phenyl methyl polysiloxanes. High activity silicones can be used, such as Dow Corning Q6-2230 silicone resin, sometimes referred to as Dow Corning ® 233 flake resin.
• the resulting-shaped green material can be optionally dried to remove the water used in forming the composition mixture.
• Conventional drying methods can be used, alone or in combination. Drying times range for a period of about one minute to about 12 hours or more. In an embodiment, drying is accomplished by placing the green material in an oven at a temperature in the range of 5O 0 C to 100 0 C, or 90 0 C to 100 0 C. Drying forms a crack-free, self-supporting structure. The support is calcined following extrusion and optional drying.
• the silicone resin is converted to silica, which acts as an inorganic binder for the particulate inorganic material in the calcined support.
• Conventional calcination conditions and equipment can be used.
• the extrudate may be calcined in an oxygen-containing atmosphere, preferably air, at a rate of 0.2 0 C to 5 0 C per minute to a temperature greater than 300 0 C, but below a temperature at which the crystallinity of the molecular sieve is adversely affected.
• such temperature will be in the range of 400 0 C to 1000 0 C, preferably below 600 0 C.
• the temperature of calcination is within the approximate range of 35O 0 C to 55O 0 C.
• the product is maintained at the calcination temperature usually for 1 to 24 hours.
• the dried support body is first calcined at a temperature in the range of 400 0 C to 1000 0 C, preferably 400 0 C to 600 0 C 5 most preferably 45O 0 C to 550 0 C, in an inert atmosphere, which is preferably flowing nitrogen.
• the preferred flow rate is within the range of 1 to 10 v/v/hr, preferably 2 to 8 v/v/hr, and most preferably is a flow rate of 5 v/v/hr.
• the first stage is undertaken for a period between 1 to 24 hours, preferably 1 to 10 hours, and most preferably for 2 hours.
• This first stage is then followed by a second calcination stage in an oxidizing atmosphere; preferably the oxidizing atmosphere is 100% air.
• the second stage is undertaken for a period of 1 to 24 hours, preferably 1 to 12 hours, and most preferably for between 6 to 13 hours.
• the flow rate for the oxidizing gas is within the range of 1 to 10 v/v/hr, preferably 2 to 8 v/v/hr, and most preferably is a flow rate of 5 v/v/hr.
• the temperature of the second stage is within the range 400 0 C to 1000 0 C, preferably 400 0 C to 600 0 C, most preferably 45O 0 C to 55O 0 C.
• the switchover from the first stage to the second stage is gradual and is typically undertaken over a period of 1 to 10 hours, more preferably 1 to 5 hours, and most preferably 2 to 4 hours.
• a silicone resin enables the particulate inorganic material to be extruded without the use of high levels of additional organic or undesirable inorganic binder materials, without excessive amounts of organic extrusion aids, and without the use of organic solvents.
• the resulting support materials can have high contents of mesoporous support material (90 wt.% or greater) and retain a degree of compressive strength after calcination. Since calcination converts in-situ the silicone resin of defined average particle size to a silica binder, the resultant calcined support contains particulate inorganic material in the presence of a primarily low acidity silica binder.
• the most common binder for molecular sieves is alumina. Using silica as a binder in molecular sieves is difficult and is not simply a matter of replacing alumina with silica.
• Conventional silica binders typically involve the use of caustic and water with the silica gel and powdered silica in the preparation of the silica binder.
• caustic may damage the support structure.
• MCM-41S family members e.g., MCM- 41, have high sorption capacity and thus require large amounts of water. This leads to processing difficulties such as over peptizing and solidifying before the mesoporous material can be extruded.
• alumina binders can alter the overall acidity of the support material.
• Alumina is more acidic than silica, thus resulting in a support that can be sufficiently acidic to cause significant olefin saturation during the hydrodesulfurization process.
• hydrodesulfurization metals can be added following calcination of the mesoporous support materials. Impregnation of the hydrodesulfurizing metal or metals on the catalyst support can be performed using incipient wetness techniques. An amount of water to just wet all of the support is determined and added. The aqueous impregnation solutions are added such that the aqueous solution contains the total amount of hydrogenation component metal(s) to be deposited on the given mass of support.
• impregnation can be performed for each metal separately, including an intervening drying step between impregnations, or as a single co-impregnation step.
• the saturated support can then be separated, drained, and dried.
• a mixture was prepared for extrusion by blending about 90 wt.% of MCM-41 crystal that had been calcined, and 10 wt.% SiO 2 equivalent of Dow Corning 6-2230 silicone resin (which had been milled to ⁇ 30 US mesh), in an Eirich mixer for 5 minutes. Water was added to adjust the solids in the mixture to 42 wt.%, and 1.5 wt.% polyvinylalcohol was added as an extrusion aid. This mixture was allowed to ball up into 1/16" (1.5875 mm) to 1/8" (3.175 mm) spheres prior to extrusion. The extrusion was run with a 1/16" (1.5875 mm) cylinder die plate and at 11.5 amps.
• Support A comprised 87 wt.% silica and 13 wt.% alumina and is the amorphous silica-alumina Davison MS- 13.
• Support B comprised Davisil amorphous silica powder of unknown purity.
• Support C comprised MCM-41 containing 90.7 wt.% silica and 9.3 wt.% alumina without binder.
• Support D comprised MCM-41 containing 99.7 wt.% silica and 0.3 wt.% alumina without binder.
• Support E comprised 35 wt.% alumina binder and 65 wt.% Support D (MCM-41 containing 99.7 wt.% silica and 0.3 wt.% alumina).
• Support F comprised 10 wt.% silica binder and 90 wt.% Support D (MCM-41 containing 99.7 wt.% silica and 0.3 wt.% alumina).
• Support A which is an amorphous silica-alumina, has an acidity measured by the Alpha test of about 1.
• the acid catalytic activity of a zeolite may be measured by its "alpha value", which is the ratio of the rate constant of a test sample for cracking normal hexane to the rate constant of a standard reference catalyst (U.S. Patent No. 3,354,078 and in The Journal of Catalysis, Vol. IV, pp. 522-529 (August 1965), both of which are incorporated herein by reference).
• the Alpha test is insensitive to differentiation of the very low levels of acidity discerned in the 2-methyl-2 pentene reaction test, differences which affect selectivity for olefin saturation during HDS.
• the amorphous silica sample, Support B has a low acidity compared with the amorphous silica-alumina (Support A).
• the framework alumina containing MCM-41, Support C shows a high acidity, nearly at the equilibrium value.
• the same mesoporous material prepared without alumina, Support D is characterized by a low acidity value.
• This support can further be formulated with a binder to achieve Support E and Support F. It is clear from this example that the addition of alumina binder to the MCM-41 material, Support E, results in much higher acidity than the MCM-41 material bound with silica, Support F. In these examples, Supports A, C and E are too acidic for use as the catalyst support.
• Catalyst A comprised Support D (MCM-41 containing 99.7 wt.% silica, 0.3 wt.% alumina) with approximately 7.4 wt.% CoO and 28.5 wt.% MoO 3 .
• Catalyst B comprised Support C (MCM-41 containing 90.7 wt.% silica and 9.3 wt.% alumina) with approximately 7.4 wt.% CoO and 28.5 wt.% MoO 3 .
• Catalysts were evaluated in the oxide form. Test results are set out in the following table.
• Catalyst A comprising MCM-41 of the highest silica content compared to the other MCM-41 catalyst, has the lowest acidity.
• Catalyst B which contains some alumina, has an appreciably higher acid strength, but is still low acidity as that term is used herein. Although the measured acidities for both of these catalysts are considered low, the inherent higher acidity of the support used to prepare Catalyst B results in higher acidity in the final catalyst. This comparison illustrates that the support acidity should be used as the indicator of acidity for the purpose of choosing a suitable support to achieve high selectivity. The example below will illustrate that the higher acidity of the support manifests as diminished catalyst selectivity in a catalyst performance test.
• Catalyst C is a CoMo/MCM-41 catalyst (7.4% CoO and 28.5% MoO 3 ) on MCM-41 containing 99.7 wt.% silica and 0.3 wt.% alumina (Catalyst A) and has been sulfided prior to use.
• Catalyst D is a CoMo/MCM-41 catalyst (7.4% CoO and 28.5% MoO 3 ) on MCM-41 containing 90.7 wt.% silica and 9.3 wt.% alumina (Catalyst B) which has also been sulfided prior to use.
• the alumina containing catalyst, Catalyst D shows lower selectivity than the lower acidity siliceous catalyst, Catalyst C. As one familiar with the art would observe, both these catalysts would traditionally be considered to demonstrate high selectivity towards retention of olefins.
• Catalysts were tested in a small pilot plant on an intermediate cat naphtha feed.
• Catalyst A comprised Support D (MCM-41) containing 99.7 wt.% silica, 0.3 wt.% alumina) with approximately 7.4 wt.% CoO and 28.5 wt.% MoO 3 .
• Catalyst E comprised Support B (Davisil amorphous silica powder of unknown purity) with approximately 7.4 wt.% CoO and 28.5 wt.% MoO 3 , The reactors were loaded with 4.0 cc of catalyst.
• the catalysts were sulfided with a 10% H 2 S/H 2 gas blend at approximately a 10 L/hr gas rate at 1652 kPa (225 psig) for two 12-hour holding periods at temperatures of 204 0 C to 343 0 C (400 0 F and 65O 0 F). Temperature was reduced to 93 0 C (200 0 F) and 100% H 2 was introduced into the reactor followed by the intermediate cat naphtha feed. The test was performed in an isothermal, downflow, all-vapor-phase pilot plant.
• the intermediate cat naphtha had a 5/95% boiling range of 68 0 C to 186 0 C (155 0 F to 367 0 F), 1425 wppm total sulfur, 33 wppm nitrogen, and 64.6 bromine number.
• the catalysts were allowed to line out on feed at 274 0 C (525 0 F) and 1652 kPa (225 psig) before the test.
• Test reactor conditions were 302 0 C (575 0 F), 356 mVm 3 (2000 scf/B), 100% hydrogen treat gas, 1652 kPa (225 psig) total inlet pressure, and an LHSV of 5.4 hr '1 .
• Product from Catalyst A had 97.73% sulfur removal and a 33.13% bromine number reduction.
• Product from Catalyst E had 96.44% sulfur removal and a 41.18% bromine number reduction.
• the catalyst based on the mesoporous-ordered (MCM- 41) support saturated fewer olefins (shows greater selectivity) than the catalyst based on an amorphous support.
• Co/Mo catalyst on a mesoporous MCM-41 support is more selective than a Co/Mo reference catalyst on an amorphous support, i.e., the mesoporous catalyst has a higher HDS/OSAT (olefin saturation) ratio than the reference catalyst.
• the catalyst based on this support is less selective (saturates more olefins) than the catalyst based on the mesoporous-ordered support.
• the novel structure of mesoporous-ordered supports increases the selectivity performance of the final catalyst.

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