WO2018164989A1 - Catalyseur zéolithique de type titanosilicate contenant des nanoparticules d'or encapsulées, procédé de synthèse et d'utilisation - Google Patents

Catalyseur zéolithique de type titanosilicate contenant des nanoparticules d'or encapsulées, procédé de synthèse et d'utilisation Download PDF

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WO2018164989A1
WO2018164989A1 PCT/US2018/020849 US2018020849W WO2018164989A1 WO 2018164989 A1 WO2018164989 A1 WO 2018164989A1 US 2018020849 W US2018020849 W US 2018020849W WO 2018164989 A1 WO2018164989 A1 WO 2018164989A1
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gold
zeolite
titanium
silica
source
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PCT/US2018/020849
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English (en)
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Ihab Nizar Odeh
Yuming Xie
C. William GUNDLACH
Alexander Nijhuis
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Sabic Global Technologies B.V.
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Publication of WO2018164989A1 publication Critical patent/WO2018164989A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/06—Preparation of isomorphous zeolites characterised by measures to replace the aluminium or silicon atoms in the lattice framework by atoms of other elements, i.e. by direct or secondary synthesis
    • C01B39/08—Preparation of isomorphous zeolites characterised by measures to replace the aluminium or silicon atoms in the lattice framework by atoms of other elements, i.e. by direct or secondary synthesis the aluminium atoms being wholly replaced
    • C01B39/085—Group IVB- metallosilicates
    • 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
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/52—Gold
    • 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
    • B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
    • 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
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • 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
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/396—Distribution of the active metal ingredient
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
    • C01B39/026—After-treatment
    • 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
    • B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
    • B01J2231/70—Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues

Definitions

  • the invention relates to zeolite catalysts, their synthesis and use.
  • Propylene oxide is a valuable chemical intermediate used in the production of valuable commercial products, such as propylene glycols and polyethers, which are then used for making products such as polyurethane.
  • Propylene oxide may be formed by the oxidation of propylene with organic peroxides. These processes, however, form organic co-products that must be separated from the propylene oxide.
  • Recently, commercial production of propylene oxide has been achieved by reacting propylene with hydrogen peroxide (H 2 O 2 ) to form propylene oxide. In this process, water (3 ⁇ 40) is the only co-product produced.
  • titanium silicalite-1 (TS-1) is used as the catalyst. Highly dispersed titanium oxide in a tetrahedral structure on silica has been confirmed to form active sites to promote formation of hydrogen-peroxy species on the surface of the catalysts.
  • TS-1 zeolites naturally provide tetrahedral T1O 2 and have been proven to be excellent catalyst supports for propylene epoxidation using H 2 O 2 .
  • Gold is typically a chemically inert metal. But when Au is formed into extremely small particles of less than 5 nm, it has been found to be a very effective catalyst. In particular, highly divided nanoscale Au ( ⁇ 5 nm) particles are known for activation of O 2 at low temperature. With such nanoscale Au particles, in the presence of O 2 and 3 ⁇ 4, hydrogen can be oxidized to form hydrogen peroxide. H 2 O 2 is short lived in the presence of these gold particles, however, so that it cannot react with other reactants.
  • the tetrahedral titanium oxide tends to hold the disassociated hydrogen peroxide that is formed with the oxidation of hydrogen by the gold particles so that it can react with other reactants, such as propylene to form propylene oxide.
  • a catalyst composition comprises a silica-titania (Si0 2 /Ti0 2 ) zeolite having a tetrahedral structure.
  • the zeolite contains gold (Au) particles encapsulated within and dispersed throughout void spaces of the zeolite.
  • the catalyst composition may have several variations.
  • the silica-titania zeolite has a Ti0 2 content of from 0.1 wt.% to 5 wt.% by total weight of the silica-titania zeolite.
  • the gold particles may have a particle size of 5 nm or less. In others, the gold particles may have a particle size of 2 nm or less.
  • the silica- titania zeolite may have an average pore size of from 1 nm or less.
  • the gold may be present within the zeolite in an amount of from 0.01 wt.% to 5 wt.% by total weight of the gold-containing zeolite.
  • the silica-titania (Si0 2 /Ti0 2 ) zeolite is at least one of a TS-1 zeolite, Ti-mordenite, and a Ti-beta zeolite.
  • a method of forming a catalyst composition may be carried out by forming an aqueous mixture comprising a silicon (Si) source, a titanium (Ti) source, a gold (Au) source, a gold complexing agent and a structure-directing agent.
  • the mixture is hydrothermally treated to provide silica-titania (Si0 2 /Ti0 2 ) zeolite having a tetrahedral structure wherein the gold (Au) particles are encapsulated within and dispersed throughout void spaces of the zeolite.
  • the method may have several variations.
  • the silicon source and titanium source may be used in the mixture in an amount to provide a Si:Ti molar ratio of from 30: 1 or more for the zeolite.
  • the gold source may provide a gold content of from 0.01 wt.% to 5 wt.% by total weight of the gold-containing zeolite.
  • the titanium source may be at least one of a titanium alkoxide, a titanium halide, a titanium nitrate, a titanium sulfate, a titanium acetoacetonate, a titanium oxyhalide, a titanium formate, and a titanium acetate.
  • the gold complexing agent may be at least one of a silicon-containing and titanium-containing compound containing at least one of phosphorus (P) and sulfur (S).
  • P phosphorus
  • S sulfur
  • alcohol produced from hydrolysis of the mixture is removed from the mixture prior to hydrothermally treating the mixture.
  • the structure-directing agent may be at least one of a tetraalkylammonium hydroxide, a tetraalkylammonium halide, tetraalkylammonium nitrate, a tetraalkylammonium sulfate, and an organoamine.
  • the silicon source may be at least one of a tetraalkyl orthosilicate, a haloalkoxysilane, an alkaline silicate, a colloidal silica, and a fumed silica.
  • the gold source may be at least one of auric chloride, chlorauric acid, gold nitrate, and gold sulfate.
  • the gold-containing zeolite may be calcined.
  • a method of forming a reaction product is carried out by contacting a catalyst composition with a reaction feed under reaction conditions suitable for producing the reaction product.
  • the catalyst composition is a silica-titania (SiOi/TiOi) zeolite having a tetrahedral structure.
  • the zeolite contains gold (Au) particles encapsulated within and dispersed throughout void spaces of the zeolite.
  • the reaction feed is oxygen and at least one of an alkene, an aromatic compound, and hydrogen.
  • FIG. 1 shows a 3-dimensional schematic representation of TS-1 zeolite containing gold (Au) particles dispersed within void spaces of the Si/Ti tetrahedral framework of the zeolite;
  • FIG. 2 is a scanning electron microscope (SEM) image of a prepared gold-containing TS-1 zeolite
  • FIG. 3 is a SEM image at lower magnification of a prepared gold-containing TS-1 zeolite observed with backscatter electron detector to image elemental contrast;
  • FIG. 4 is an XRD plot of the gold-containing TS-1 catalyst of Sample 6 from Table 1 of Example 1, showing that it has a TS-1 zeolite structure.
  • FIG. 5 is an XRD plot of the gold-containing TS-1 catalyst of Sample 9 from Table 1 of Example 1, showing that it has a TS-1 zeolite structure.
  • FIG. 6 is a plot of propene oxide yield, propene conversion, and hydrogen efficiency for the gold-containing TS-1 catalyst of Sample 6 from Table 1 of Example 1 used in the propene epoxidation of Example 2;
  • FIG. 7 is a plot of propene oxide yield, propene conversion, and hydrogen efficiency for gold-containing TS-1 catalyst of Sample 9 from Table 1 of Example 1 used in the propene epoxidation of Example 2.
  • Titanosilicate materials such as TS-1 zeolite, Ti-mordenite, and Ti-beta zeolite, have small pore sizes of 1 nm or less.
  • the pore size is typically at 0.55 nm.
  • the pore sizes are typically at 0.65 nm X 0.65 nm.
  • the pore sizes are typically 0.55 nm X 0.70 nm.
  • gold is deposited on the outer surface of such titania- silica support materials it cannot enter the small pore channels, but instead remains solely on the outer surface of the zeolite.
  • gold ions typically do not enter and become deposited within the pore channels of the titania- silica support materials. This is because titanosilicate materials, such as TS-1, Ti- mordenite and Ti-beta, do not contain ion exchange sites as do silica/alumina zeolite materials. Gold ions (e.g., Au + or Au 3+ ) therefore do not enter or migrate into the pore channels through ion exchange mechanisms, as may occur in metal ion treatments of silica/alumina materials that do contain such ion exchange sites.
  • FIG. 1 shows a 3-dimensional schematic of such a structure for a TS-1 zeolite containing gold particles.
  • the nanocluster sizes appear to be limited by the zeolite channel dimensions and the resulting nanoclusters of Au° are protected against coalescence and poisoning by their uniform dispersion and encapsulation within the void spaces of the zeolite.
  • the catalyst composition can be prepared through hydrothermal synthesis wherein an aqueous mixture comprising a silicon (Si) source, a titanium (Ti) source, a gold (Au) source, a gold complexing agent and a structure-directing agent are combined and then hydrothermally treated to provide a silica-titania (Si0 2 /Ti0 2 ) zeolite wherein the gold (Au) particles are encapsulated within and dispersed throughout void spaces of the zeolite.
  • aqueous mixture comprising a silicon (Si) source, a titanium (Ti) source, a gold (Au) source, a gold complexing agent and a structure-directing agent are combined and then hydrothermally treated to provide a silica-titania (Si0 2 /Ti0 2 ) zeolite wherein the gold (Au) particles are encapsulated within and dispersed throughout void spaces of the zeolite.
  • the titanium (Ti) is integrated into the framework of the zeolite as highly dispersed titanium oxide in a tetrahedral geometry. Titanium is difficult to build into the framework, however. Typically, no more than a 1:50 molar ratio of Ti:Si, which is equivalent to approximately 3 wt.% Ti0 2 or 1.8 wt.% Ti by weight of the titanosilicate structure can be included. The use of higher amounts of titanium during synthesis can result in different phase materials from the desired Si0 2 / i0 2 zeolite structure.
  • the titanium source may be a hydrolyzable titanium compound that provides a source of titanium oxide.
  • the hydrolyzable titanium compound used for the titanium source may include a titanium alkoxide, such as tetramethyl orthotitanate, tetraethyl orthotitanate (TEOT), tetrapropyl orthotitanate (TPOT), and tetrabutyl orthotitanate (TBOT).
  • TEOT tetramethyl orthotitanate
  • TPOT tetrapropyl orthotitanate
  • TBOT tetrabutyl orthotitanate
  • titanium sources may include titanium halides (e.g., TiF 4 , TiF 3 , TiCl 4i TiCl 3 , TiCl 2 , TiBr 4 , TiL , titanium oxyhalides (e.g., TiOCl 2 ), titanium tetranitrates, titanium sulfates, titanium acetoacetonate, titanium formate, and titanium acetate. Combinations of these materials may also be used. These materials may be used to provide a Si:Ti molar ratio of from 30: 1 to 40: 1 or more of the synthesized titanosilicate zeolite.
  • titanium halides e.g., TiF 4 , TiF 3 , TiCl 4i TiCl 3 , TiCl 2 , TiBr 4 , TiL
  • titanium oxyhalides e.g., TiOCl 2
  • Ti tetranitrates titanium sulfates
  • titanium acetoacetonate titanium formate
  • the titanium may be used to provide a Ti0 2 content of from 0.1 wt.% to 5 wt.% by total weight of the silica-titania zeolite or from 0.06 wt.% to 3.0 wt.% of Ti by weight of the titanosilicate structure.
  • the Si:Ti molar ratio will be from 50: 1 or higher.
  • the titanium may be used to provide a Ti0 2 content of from 1.0 wt. % to 4 wt.% by total weight of the titanosilicate zeolite or from 0.6 wt.% to 2.5 wt.% of Ti by weight of the titanosilicate structure.
  • the Si:Ti molar ratio is lower than 50: 1, some amounts of Ti may be present as an amorphous or crystalline Ti0 2 as a secondary phase.
  • the silicon source may be a hydrolyzable or non-hydrolyzable silicon compound that is used to provide the zeolite primarily composed of Si0 2 with Ti atoms in tetrahedral geometry and dispersed throughout the silicate structure.
  • the amount of silicon source used is determined by the relative ratio of Si:Ti or Si0 2 :Ti0 2 discussed previously.
  • Non-limiting examples of the silicon source include at least one of a tetraalkyl orthosilicate, an alkaline silicate, a colloidal silica, or a fumed silica.
  • suitable colloidal silica may include those marketed under the name LUDOX ® , available from Sigma-Aldrich, which may be in the form of aqueous silica suspensions.
  • the silicon source may include tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS).
  • a templating or structure-directing agent is used in the synthesis to aid in forming the crystalline Si0 2 /Ti0 2 structure.
  • This is typically a nitrogen-containing organic base, such as quaternary ammoniums, which direct the formation of the MFI zeolite structure.
  • structure-directing agents include tetraalkylammonium hydroxides, tetraalkylammonium halides, and organoamines.
  • tetrapropylammonium hydroxide (TPAOH) may be used as the structure-directing agent.
  • the amount of structure-directing agent used is sufficient to stabilize the desired zeolite framework and broadly includes a SDA:Si molar ratio of greater than 0 to 0.20.
  • the structure-directing agent may be used in an amount of from 0.01 to 0.10 SDA: Si molar ratio.
  • the gold source used in the synthesis may be that which provides gold ions in solution, which may be Au 3+ cations, during the synthesis.
  • suitable gold sources include auric halide such as fluoride, chloride, bromide, iodide, auric cyanide, chloroauric acid, bromoauric acid, gold hydroxide, gold nitrate, and gold sulfate.
  • the gold source is used in an amount to provide from 0.01 wt.%, 0.02 wt.%, 0.03 wt.%, 0.04 wt.%, 0.05 wt.%, 0.06 wt.%, 0.07 wt.%, 0.08 wt.%, 0.09 wt.%, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, or 1 wt.% to 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, or 5 wt.% of gold by total weight of the gold- containing titanosilicate zeolite catalyst composition.
  • the gold source may be used in an amount to provide from 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, or 1 wt.% to 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, or 5 wt.% of gold by total weight of the gold-containing titanosilicate zeolite catalyst composition.
  • a gold complexing agent is used to facilitate dispersing the gold ions during synthesis throughout the synthesis gel.
  • One portion of the complexing agent may contain a silicon or titanium moiety that can be incorporated into the crystalline Si0 2 /Ti0 2 structure either as-is or after a reaction, such as hydrolysis.
  • the gold complexing agent should also not release chemicals that are not compatible with zeolite formation.
  • a preferred moiety for incorporation the Si0 2 /Ti0 2 structure is a trialkoxysilane.
  • the gold complexing agent also has or contains a functional group(s) that attracts, binds or otherwise complexes with the gold ions so that they are dispersed and drawn into the synthesis gel and into the resulting zeolite structure.
  • This functionality may be provided by sulfur (S) and/or phosphorus (P) atoms, which may be in the form of thiol (mercapto) or phosphine moieties.
  • Non-limiting examples of suitable compounds for use as the gold complexing agent include mercaptoalkyl trialkyloxysilanes, such as 3-mercaptopropyl trimethyloxysilane (3-MPTS), 4-mercapto-n-butyltrimethoxysilane, and 3-mercaptopropyl triethoxysilane.
  • mercaptoalkyl trialkyloxysilanes such as 3-mercaptopropyl trimethyloxysilane (3-MPTS), 4-mercapto-n-butyltrimethoxysilane, and 3-mercaptopropyl triethoxysilane.
  • the gold complexing agent is typically used in an amount to complex with all the gold so that it is fully dispersed. This may be in an amount so that the gold complexing functional groups of the gold complexing agent are used in at least a 1: 1 molar ratio or more with respect to the gold used.
  • the silicon or titanium of the gold complexing agent is incorporated into the silicate structure of the zeolite, it also functions as a silicon or titanium source and the amount of silicon or titanium from the gold complexing agent should be taken into account with respect to the relative amounts of Si and Ti and Si0 2 and Ti0 2 , as was discussed earlier.
  • the titanium and silicon sources, as well as other compounds used in the synthesis be free or substantially free from impurities.
  • impurities may include minor amounts of Al, Fe, Na, Mg, Ca, etc., as well as residual materials from the synthesis precursors, such as S or P from the gold complexing agent that are not completely removed during the catalyst formation.
  • these materials will be present in the final catalyst composition in amounts of less than 0.1 wt. % by weight of the catalyst composition.
  • an aqueous mixture of the catalyst precursors is prepared. This may be carried out in sequential steps.
  • an aqueous solution of the structure-directing agent, such as TPAOH is combined or admixed with the gold complexing agent, such as 3-MPTS.
  • the structure-directing agent which may be a nitrogen-containing organic base, serves as a base to hydrolyze the silane functional groups of the gold complexing agent to form the silicon- containing oligomer or polymer chain structure with the -Si-O-Si- linkages and gold complexing functional groups, as discussed previously.
  • such structure-directing agent may be used in excess (e.g., > 50 wt. %) to that needed in synthesizing the Si0 2 /Ti0 2 structure to promote the hydrolysis of the gold complexing agent.
  • the gold source which may be gold cations in an aqueous solution.
  • the gold source may be added gradually to this solution to prevent local large concentrations of gold from forming in solution that could tend to form larger gold particles.
  • This step is typically operated at or near room temperature.
  • the amount of gold solution added is kept at or near a 1 : 1 ratio of gold to the gold complexing agent to ensure all gold is complexed with the gold complexing agent. This forms a first solution of the gold with the gold complexing agent.
  • the titanium source may be combined or admixed at or near 0 °C with an aqueous solution of a structure-directing agent, such as TPAOH, to form a titanium sol.
  • a structure-directing agent such as TPAOH
  • TPAOH structure-directing agent
  • the titanium source may be added gradually to prevent high local Ti concentrations so that the Ti remains isolated and to prevent the precipitation of titanium hydroxide or titanium oxide, which tends to readily precipitate.
  • the temperature is typically maintained below 4 °C.
  • the amount of the titanium source used is determined by the targeted zeolite Si:Ti molar composition.
  • the titanium sol may then be admixed with the first solution of gold with the gold complexing agent to form a third solution containing the titanium sol gel and gold with the gold complexing agent.
  • the silicon source such as TEOS
  • TEOS is immediately added to this third solution at or near room temperature. This may be added with additional water being added to the third solution or the silicon source may be added as an aqueous solution to better facilitate zeolite synthesis.
  • the total water volume is controlled to be about twice of volume of TEOS added.
  • This forms a fourth solution of a synthesis gel, containing a silica sol gel and titanium sol gel with the gold and the gold complexing agent.
  • This solution is then mixed at or near room temperature for a sufficient period of time (e.g., 2 hrs to 48 hrs or more) to ensure thorough dispersal of the titanium and gold throughout the final synthesis gel. Such mixing may occur at ambient conditions.
  • alkyl alcohols may be formed, such as methanol from the hydrolysis of 3-MTPS, ethanol from the hydrolysis of TEOS, and butanol from the hydrolysis of TBOT.
  • Such residual alcohols can act as reductants of the Au cations, particular at higher temperatures, so that removal of these alcohols may be desired prior to the hydrothermal treatment.
  • the alcohols may be removed at various stages during the reaction steps and prior to crystallization by evaporative separation where the various solutions are subjected to heat and/or vacuum to drive off these alcohols.
  • the alcohols are driven off after all the precursors are combined to form the final synthesis gel. This may occur by heating the final mixture to a temperature of 100 °C or less.
  • the alcohols may be removed by evaporation under reduced pressure.
  • the final synthesis gel may be heated to dryness to ensure all or substantially all the alcohol is removed.
  • the resulting solid may be ground to a fine powder to ensure homogeneity and then reconstituted by suspending it in an aqueous solution containing a structure-directing agent.
  • the amount of structure-directing agent may be from greater than 0 to 0.20 SDA:Si molar ratio, more particularly from 0.01 to 0.10 SDA:Si molar ratio. Additional water added is several times (e.g., 6-8) the weight of the dried gel weight.
  • the gold source is not added to the initial solution of structure-directing agent and gold complexing agent. In such case, all the other precursors are combined, however, as describe previously.
  • This solution containing the synthesis gels absent the gold source is then subjected to heating to a temperature of 100 °C or less with or without vacuum to dryness to remove alcohols. This may be done in oxygen-free conditions to eliminate oxygen exposure that can cause oxidation of thiols to disulfides, which may hinder Au cation complexation.
  • the resulting solid is ground to a fine powder and then reconstituted by suspending the powder with additional structure-directing agent and water, in the same manner as was described previously.
  • the gold source is then admixed with the suspension for a sufficient period of time (e.g., 2 hrs to 48 hrs or more) to ensure thorough dispersal of the titanium and gold throughout the synthesis gel.
  • the gold source and the gold complexing agent are not added to the initial solution of structure-directing agent.
  • all the other precursors of the titanium and silicon sources are combined in solution with the structure- directing agent, as describe previously.
  • This solution containing the synthesis gels, absent the gold source and gold complexing agent is then subjected to heating to a temperature of 100 °C or less with or without vacuum to dryness to remove alcohols. After drying, the resulting solid is ground to a fine powder and then reconstituted by suspending the powder with additional structure-directing agent and water, in the same manner as was described earlier.
  • the gold source and gold complexing agent are then admixed with the suspension for a sufficient period of time (e.g., 2 hrs to 48 hrs or more) to ensure thorough dispersal of the titanium and gold throughout the synthesis gel.
  • the final synthesis gel, as formed in solution or reconstituted, as described above, is then hydrothermally treated to facilitate crystallization.
  • This may be conducted in an autoclave with agitation to facilitate mixing within the liquid suspension and to avoid local concentration differences. Heating temperatures may range from 120 °C to 180 °C, more particularly from 160 °C to 180 °C. Pressures encountered during the hydrothermal treatment may range from 800 kPa to 1200 kPa.
  • the hydrothermal treatment may be continued for a sufficient period of time to ensure complete or substantially complete crystallization. This may be for several hours to several days (e.g., 2 days to 1 week or more).
  • the product is cooled and the liquids are separated from the solids.
  • the solids are washed, such as with deionized water, and the resulting crystals are dried. Drying temperatures may range from 80 °C to 120 °C.
  • the zeolite crystals may be calcined in dry air or oxygen wherein the zeolite crystals are heated through stepwise or ramped heating to the final calcination temperatures.
  • stepwise or ramped heating prevents high concentrations of steam being formed during calcination.
  • High steam concentrations formed during calcination can damage the zeolite.
  • Final calcination temperatures may range from 400 °C to 450 °C, which may be maintained from 1 hr to 4 hrs or more.
  • the zeolite crystals may be cooled to less than 100 °C and then purged using a flow of an inert gas, such as nitrogen, to remove oxygen.
  • the calcined crystals may then be subjected to hydrogen gas (H 2 ) with stepwise or ramped heating (e.g., 1 °C/min to 5 °C/min) to a final temperature of from 400 °C to 450 °C for 1 or more hours. Thereafter, the zeolite crystals may be cooled and subjected to purging with an inert gas, such as nitrogen.
  • the resulting composition formed is a silica-titania (Si0 2 /Ti0 2 ) zeolite having a tetrahedral structure with gold (Au°) nanoparticles encapsulated within and dispersed throughout void spaces of the formed zeolite crystals.
  • These gold nanoparticles may have a particle size of from 5 nm or less. In certain embodiments, the gold nanoparticles may have a particle size of 2 nm or less.
  • the gold nanoparticles may have a particle size of from 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, or 1 nm to 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, or 2 nm.
  • Gold particles size may be determined through transmission electron microscopy (TEM) or extended X-ray absorption fine structure (EXAFS) measurement techniques.
  • TEM transmission electron microscopy
  • EXAFS extended X-ray absorption fine structure
  • a TS-1 zeolite is the silica-titania (Si0 2 /Ti0 2 ) zeolite that is formed.
  • a Ti- mordenite or Ti-beta zeolite is the silica-titania (Si0 2 /Ti0 2 ) zeolite that is formed.
  • Such zeolites typically have average pore sizes of less than 1 nm, however, the gold particles can be greater than such pore channel size due some Si-O-Si or Si-O-Ti bonds being locally broken, while the overall zeolite structure is still maintained.
  • the gold nanoparticles of less than 5 nm of the formed catalyst facilitate the activation of 0 2 at low reaction temperatures.
  • Such low reaction temperatures may range from 50 °C to 300°C, more particularly from 100 °C to 250 °C, and still more particularly from 150 °C to 225 °C.
  • hydrogen can be oxidized to form hydrogen peroxide so that hydrogen peroxide does not have to be used as an added reactant but is instead created in situ during the reaction.
  • the tetrahedral titanium oxide of the silica-titania zeolite structure tends to hold the disassociated hydrogen peroxide that is formed with the oxidation of hydrogen by the gold particles so that it can react with other reactants, such as propylene to form propylene oxide.
  • Such catalyst may also be used for similar selective oxidation of other hydrocarbons in the presence of oxygen and hydrogen.
  • the reaction feed may include oxygen and at least one of an alkene and/or an aromatic compound, and hydrogen. Examples of these reactions may include propylene to propylene oxide, butene to butene oxide, pentene to pentene oxide, benzene to phenol, etc.
  • an additional co-feed of carbon monoxide (CO) may be used in small amounts (e.g., ⁇ 5 vol. %) in the epoxidation reactions. This may facilitate reducing the amount of unwanted alkanes that may be produced as side reactions.
  • CO carbon monoxide
  • Step 1 Tetrapropyl ammonium hydroxide (TPAOH) at 8.25 ml as a 2M TPAOH solution diluted with 8.25 ml of water was combined with 3-mercaptopropyltrimethoxysilane in various amounts as presented in Table 1 below. These were mixed in a 100 ml polypropylene reaction bottle and stirred for 8 hrs at ambient conditions to make Solution 1.
  • TPAOH Tetrapropyl ammonium hydroxide
  • Step 2 HAuCl 4 in 1.88 ml of deionized water in the amounts listed in Table 1 below was added dropwise to the solution of Step 1 to make Solution 2.
  • Step 3 Tetrabutylorthotitanate (TBOT) in the amounts listed in Table 1 below was added dropwise to an 8.25 ml as a 2M TPAOH solution diluted with 8.25 ml of water at 0 °C for 60 minutes to form Solution 3.
  • TBOT Tetrabutylorthotitanate
  • Step 4 Solution 2 from Step 2 was added to Solution 3 of Step 3 to form Solution 4.
  • Step 5 Tetraethylorthosilicate (TEOS) at 17.3 g was added to Solution 4 of Step 4 and additional water was added, as set forth in Table 1 below.
  • TEOS Tetraethylorthosilicate
  • Step 6 The reaction bottle was capped and stirred for 13 hrs or more at ambient conditions.
  • Step 7 The product mixture from Step 6 was uncapped and heated in a water bath at 60 °C for 2 hrs in a fume hood to reduce alcohol concentration.
  • Step 8 The resulting solution from Step 7 was transferred to PTFE-lined autoclaves, sealed, and then heated to 170 °C with end-over-end tumbling and held at temperature for 3 days.
  • Step 9 The product from Step 8 was cooled to ambient temperature and was centrifuged and decanted to separate liquids and solids of the formed zeolite crystals. The solids were washed three times with deionized water and the collected zeolite crystals were dried at 90 °C overnight.
  • Step 10 The dried zeolite was heated in dry air flow (100 seem) to 273 °C at 1 °C/min and held at that temperature for 2 hrs. The temperature was raised to 375 °C at 1 °C/min and held for 2 hrs. This was followed by an increase of temperature to 450 °C at 1 °C/min, which was held for 4 hrs.
  • Step 11 The calcined product from Step 10 was cooled to less than 100 °C and subjected to nitrogen gas (N 2 ) flow so that the product was nitrogen purging from >15 min. The gas flow was then switched to H 2 gas (100 seem) flow and the samples were heated to 273 °C at 1 °C/min and held at temperature for 2 hrs. After cooling, the samples were purged with flowing N 2 .
  • N 2 nitrogen gas
  • Catalysts 6 and 9 from the above Table 1 were analyzed for their chemical compositions and surface area. The results are presented in Table 2 below.
  • FIG. 2 shows the typical SEM result of the prepared Au-containing TS-1 zeolites. As can be seen, the particles are in the size range of 200-400 nm with well defined crystals.
  • FIG. 3 shows a lower SEM magnification observed with the backscatter electron detector to image elemental contrast. As can be seen, some larger particles of gold (in the tens of nm size) were visible due to alcohol reduction during the zeolite synthesis. Large gold particles are catalytically inactive. The activity of the prepared catalyst is attributed to the SEM-invisible nanosized Au encapsulated inside of zeolite pore channels.
  • FIGS. 4-5 show XRD diffraction plots for catalyst Samples 6 and 9, respectively, each showing that the zeolite possesses the TS-1 structure.
  • the resulting gold-containing TS-1 zeolite catalysts from Example 1 were tested in a packed bed flow reactor at various reaction conditions in a single experimental run.
  • a catalyst quantity of 300 mg was loaded into a reactor, diluted with 500 mg of silicon carbide to assure good heat transfer and even temperature within the catalyst bed.
  • the standard reaction condition was repeated throughout the catalytic experiment to determine the catalyst stability.
  • the initial reactant feed rate was 50 seem of a blend of 10 vol.% 0 2 , 10 vol.% H 2 , 10 vol.% propene, and the balance N 2 at a temperature of 120 °C and 700 kPa pressure.
  • the pressure was varied from 400 kPa to 1200 kPa
  • the reaction temperature was varied from 120 °C to 250 °C
  • the propene content was varied from 10 vol.% to 40 vol.%.
  • the catalyst performance was monitored for 8 hrs, during which all relevant reaction products were analyzed. Typically, each catalyst was tested at 20- 25 different conditions, during which the standard reaction condition was repeated 5 times. Before the first catalytic condition and between the different reaction conditions, the catalysts were activated/regenerated at 300°C in 10 vol. % oxygen in N 2 at 31 seem for 3 hrs. Irreversible deactivation was the main indication of sintering of the gold particles
  • FIGS. 6-7 show the propene oxide yield, propene conversion, and hydrogen efficiency for the gold-containing TS-1 zeolite catalyst of Sample Nos. 6 and 9, respectively, from Table 1.
  • each segment represents the catalytic performance of the catalyst at 120 °C and 700 kPa pressure in an 8 hour run. Samples of the gas leaving the reactor were taken once per hour. The plots are not continuous so the vertical lines represent breaks where data at other conditions is not presented.

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Abstract

Cette invention concerne une composition de catalyseur zéolithique de type silice-oxyde de titane (SiO2/TiO2) ayant une structure tétraédrique qui contient des nanoparticules d'or (Au), où les particules d'or (Au) sont encapsulées et dispersées dans tous les espaces vides de la zéolithe. Le catalyseur peut être préparé par formation d'un mélange aqueux d'une source de silicium (Si), d'une source de titane (Ti), d'une source d'or (Au), d'un agent complexant l'or et d'un agent d'orientation de structure. Le mélange est traité par voie hydrothermale pour obtenir une zéolithe de type silice-oxyde de titane (SiO2/TiO2) ayant une structure tétraédrique dans laquelle les particules d'or (Au) sont encapsulées et dispersées dans tous les espaces vides de la zéolithe. La composition de catalyseur peut être mise en contact avec une charge de réaction dans des conditions de réaction appropriées pour obtenir le produit réactionnel.
PCT/US2018/020849 2017-03-06 2018-03-05 Catalyseur zéolithique de type titanosilicate contenant des nanoparticules d'or encapsulées, procédé de synthèse et d'utilisation WO2018164989A1 (fr)

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CN111841623A (zh) * 2020-08-19 2020-10-30 河南大学 分子筛催化剂及其制备方法及用途
CN113441136A (zh) * 2021-06-25 2021-09-28 中山大学 一种原位封装纳米贵金属的多级孔催化剂的制备与应用
CN116332195A (zh) * 2021-12-22 2023-06-27 中国石油化工股份有限公司 多级孔钛硅分子筛及其制备方法和催化氧化环己烯的方法

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Publication number Priority date Publication date Assignee Title
CN109399659A (zh) * 2018-11-16 2019-03-01 华东理工大学 一种小尺寸金纳米颗粒负载的钛硅沸石及其制备方法
WO2020116470A1 (fr) * 2018-12-03 2020-06-11 国立大学法人北海道大学 Structure fonctionnelle
JPWO2020116470A1 (ja) * 2018-12-03 2021-12-09 国立大学法人北海道大学 機能性構造体
CN111841623A (zh) * 2020-08-19 2020-10-30 河南大学 分子筛催化剂及其制备方法及用途
CN111841623B (zh) * 2020-08-19 2021-09-24 河南大学 分子筛催化剂及其制备方法及用途
CN113441136A (zh) * 2021-06-25 2021-09-28 中山大学 一种原位封装纳米贵金属的多级孔催化剂的制备与应用
CN116332195A (zh) * 2021-12-22 2023-06-27 中国石油化工股份有限公司 多级孔钛硅分子筛及其制备方法和催化氧化环己烯的方法

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