CN115283011A - Method for improving dispersity of gold nanoparticles of titanium-silicon molecular sieve supported gold catalyst and application of gold nanoparticles - Google Patents
Method for improving dispersity of gold nanoparticles of titanium-silicon molecular sieve supported gold catalyst and application of gold nanoparticles Download PDFInfo
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- CN115283011A CN115283011A CN202211026338.5A CN202211026338A CN115283011A CN 115283011 A CN115283011 A CN 115283011A CN 202211026338 A CN202211026338 A CN 202211026338A CN 115283011 A CN115283011 A CN 115283011A
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- 239000010931 gold Substances 0.000 title claims abstract description 66
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 66
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 54
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 239000003054 catalyst Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 24
- 239000002105 nanoparticle Substances 0.000 title claims abstract description 18
- UGACIEPFGXRWCH-UHFFFAOYSA-N [Si].[Ti] Chemical compound [Si].[Ti] UGACIEPFGXRWCH-UHFFFAOYSA-N 0.000 title claims abstract description 12
- 239000010936 titanium Substances 0.000 claims abstract description 52
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 44
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 44
- 239000002245 particle Substances 0.000 claims abstract description 20
- GOOHAUXETOMSMM-UHFFFAOYSA-N Propylene oxide Chemical compound CC1CO1 GOOHAUXETOMSMM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims abstract description 11
- 238000004108 freeze drying Methods 0.000 claims abstract description 10
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims abstract description 8
- 239000002243 precursor Substances 0.000 claims description 11
- 238000006735 epoxidation reaction Methods 0.000 claims description 9
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 6
- 239000002253 acid Substances 0.000 claims description 6
- 239000004202 carbamide Substances 0.000 claims description 6
- 230000003213 activating effect Effects 0.000 claims description 5
- 239000012716 precipitator Substances 0.000 claims description 5
- 230000004913 activation Effects 0.000 claims description 4
- 229910052792 caesium Inorganic materials 0.000 claims description 4
- 239000002149 hierarchical pore Substances 0.000 claims description 4
- 229910052744 lithium Inorganic materials 0.000 claims description 4
- 229910052700 potassium Inorganic materials 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- WPEJSSRSFRWYJB-UHFFFAOYSA-K azanium;tetrachlorogold(1-) Chemical compound [NH4+].[Cl-].[Cl-].[Cl-].[Cl-].[Au+3] WPEJSSRSFRWYJB-UHFFFAOYSA-K 0.000 claims description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 2
- 239000011591 potassium Substances 0.000 claims description 2
- 229910052708 sodium Inorganic materials 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 230000003197 catalytic effect Effects 0.000 abstract description 7
- 238000007254 oxidation reaction Methods 0.000 abstract description 6
- 230000003647 oxidation Effects 0.000 abstract description 5
- 238000005054 agglomeration Methods 0.000 abstract description 3
- 230000002776 aggregation Effects 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 230000001588 bifunctional effect Effects 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000012018 catalyst precursor Substances 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- 229910052739 hydrogen Inorganic materials 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 5
- 238000012512 characterization method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000000731 high angular annular dark-field scanning transmission electron microscopy Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
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- 241000282326 Felis catus Species 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- XENVCRGQTABGKY-ZHACJKMWSA-N chlorohydrin Chemical compound CC#CC#CC#CC#C\C=C\C(Cl)CO XENVCRGQTABGKY-ZHACJKMWSA-N 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000005216 hydrothermal crystallization Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- GQZXNSPRSGFJLY-UHFFFAOYSA-N hydroxyphosphanone Chemical compound OP=O GQZXNSPRSGFJLY-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
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- 239000000126 substance Substances 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
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- 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
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D301/00—Preparation of oxiranes
- C07D301/02—Synthesis of the oxirane ring
- C07D301/03—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds
- C07D301/04—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen
- C07D301/08—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase
- C07D301/10—Synthesis of the oxirane ring by oxidation of unsaturated compounds, or of mixtures of unsaturated and saturated compounds with air or molecular oxygen in the gaseous phase with catalysts containing silver or gold
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms
-
- 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
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
- B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
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- Epoxy Compounds (AREA)
Abstract
The invention belongs to the technical field of catalysts, and provides a method for improving the dispersity of gold nanoparticles of a titanium-silicon molecular sieve supported gold catalyst. Compared with the prior art, the freeze drying technology can obviously reduce the agglomeration degree of titanium silicalite molecular sieve particles, and the prepared nano gold particles on the titanium silicalite molecular sieve supported gold catalyst have higher dispersity. When the prepared gold catalyst is used in the reaction of preparing propylene oxide by propylene oxidation, the catalyst shows higher catalytic activity.
Description
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to a method for improving the dispersity of gold nanoparticles of a titanium-silicon molecular sieve supported gold catalyst and application thereof.
Background
Propylene Oxide (PO) is the second largest Propylene derivative next to polypropylene, and is mainly used for producing chemical products such as polyether polyol and Propylene glycol. Compared with the prior chlorohydrin method, the co-oxidation method and the direct hydrogen peroxide oxidation method for industrially producing PO, the method has the advantages that propylene is subjected to H 2 /O 2 The PO is directly synthesized by epoxidation in the atmosphere, namely the HOPO process has the unique advantages of cheap and easily obtained raw materials, simple process, green and environment-friendly process and the like, and is always regarded as an ideal process for producing PO for a long time.
At present, the catalyst used for catalyzing propylene to generate PO by hydrogen oxidation is a nano-gold catalyst immobilized on a titanium silicalite molecular sieve. The titanium silicalite molecular sieve supported gold catalyst is an Au-Ti bifunctional catalyst: au site catalysis H 2 And O 2 Hydroperoxide species are formed which then diffuse to the Ti sites to form Ti-OOH reactive intermediates, with which propylene reacts to form PO.
A great deal of research finds that the grain size of the gold nanoparticles is a key factor influencing the performance of the Au-Ti bifunctional catalyst. Generally, the gold nanoparticles with smaller particle size help to promote the adsorption of oxygen because more Corner sites are exposed, so that the generation rate of hydroperoxide species on the gold nanoparticles is increased, and finally, higher catalytic activity is shown, and the properties of the titanium silicalite molecular sieve have important influence on the particle size of the gold nanoparticles. Generally speaking, improving the dispersity of titanium silicalite molecular sieve particles is beneficial to promoting the uniform loading of gold precursors on the surface of the molecular sieve in the catalyst preparation process, so as to obtain higher dispersity of nano-gold particles.
According to literature reports, the drying method of the nano molecular sieve has a significant influence on the agglomeration degree of nano molecular sieve particles. Generally, because the surface tension of water is very high, water adsorbed on the nano molecular sieve particles is easily evaporated when the nano molecular sieve sample is dried at a high temperature, so that the nano molecular sieve particles are aggregated into a large number of aggregates with larger sizes, and therefore, if the surface tension of water molecules adsorbed on the surfaces of the nano molecular sieve particles can be effectively reduced, the dispersion degree of titanium silicalite molecular sieve particles can be improved, so that the uniform loading of a gold precursor on the surfaces of the titanium silicalite molecular sieve is promoted, the dispersion degree of nano gold particles is further improved, and finally, the performance of a titanium silicalite molecular sieve solid-supported gold catalyst in an propylene-hydrogen-oxygen epoxidation reaction is improved. At present, the influence of the drying mode of the titanium silicalite molecular sieve on the performance of the supported gold catalyst in the epoxidation reaction of the propylene oxide and hydrogen oxide is not reported.
Disclosure of Invention
In view of the above, the present invention provides a method for improving the dispersity of gold nanoparticles in a titanium silicalite molecular sieve supported gold catalyst, which improves the dispersity of gold nanoparticles by using a freeze-dried unfired titanium silicalite molecular sieve supported gold, and the prepared titanium silicalite molecular sieve supported gold catalyst shows higher catalytic activity when used in a reaction of preparing PO by propylene oxidation.
The technical scheme of the invention is as follows: the method for improving the dispersity of gold nanoparticles of a titanium-silicon molecular sieve-supported gold catalyst is characterized by taking a freeze-dried unfired titanium-silicon molecular sieve as a carrier, mixing a gold precursor solution, a precipitator and the freeze-dried unfired titanium-silicon molecular sieve, and then drying and activating the mixture to obtain the titanium-silicon molecular sieve-supported gold catalyst.
The invention is further set that the preparation process of the titanium silicalite molecular sieve supported gold catalyst comprises the steps of adding a freeze-dried unfired titanium silicalite molecular sieve into a mixed solution containing water, a gold precursor solution and a precipitator, uniformly mixing, placing the obtained catalyst precursor at room temperature for vacuum drying, and finally activating the dried catalyst precursor to obtain the Au-Ti bifunctional catalyst.
The uncalcined titanium silicalite molecular sieve subjected to freeze drying treatment in the invention is prepared by a conventional hydrothermal method, and after the hydrothermal crystallization process is finished, the uncalcined titanium silicalite molecular sieve is obtained through solid-liquid separation.
The invention is further configured that the unfired titanium silicalite molecular sieve comprises one or more of Ti-SBA-15, ti-MCM-41, ti-MCM-48, ti-MCM-36, ti-MWW, ti-MOR, ti-Beta, ti-TUD-1, TS-1, hierarchical pore TS-1, TS-2 and hierarchical pore TS-2.
The invention is further configured that the temperature of the non-calcined titanium silicalite molecular sieve freeze drying is-80-0 ℃, preferably-50-0 ℃.
The invention further provides that the time for freeze drying the unfired titanium silicalite molecular sieve is 24-96h, preferably 36-48h.
The invention is further configured that the unfired titanium silicalite molecular sieve is pre-frozen at-10 to 0 ℃ for 2 to 8 hours before freeze-drying.
The invention is further provided that the gold precursor in the gold precursor solution is selected from one or more of chloroauric acid, sodium chloroaurate, potassium chloroaurate, cesium chloroaurate, lithium chloroaurate or ammonium chloroaurate.
The invention further provides that the precipitant is selected from MOH and M 2 CO 3 One or more of urea and ammonia water, wherein M is Li, na, K, rb or Cs.
The invention further provides that the activation treatment is carried out in the presence of an activating atmosphere, wherein the activating atmosphere is air, reducing atmosphere or inert atmosphere; the activation temperature is 150 to 400 ℃, preferably 200 to 350 ℃, more preferably 300 to 320 ℃.
In a second aspect of the invention, a titanium silicalite molecular sieve supported gold catalyst prepared by the method is provided.
The invention further provides that the particle size of the gold nanoparticles on the titanium silicalite supported gold catalyst is less than 5nm, preferably less than 2.5nm.
The third aspect of the invention provides an application of the titanium silicalite molecular sieve gold-supported catalyst in the reaction of preparing PO by the epoxidation of propylene with hydrogen and oxygen.
The invention has the following beneficial effects: compared with the traditional drying mode, the agglomeration degree of titanium silicalite nano particles is obviously reduced by carrying out low-temperature freeze drying treatment on the non-roasted titanium silicalite molecular sieve, the particle size of nano gold particles on the gold catalyst immobilized by adopting the freeze-dried non-roasted titanium silicalite molecular sieve as a carrier is obviously smaller, and the prepared gold catalyst shows higher catalytic activity in the reaction of preparing PO by propylene-hydrogen oxidation.
Drawings
FIG. 1 is an SEM image of a sample of an unfired titanium silicalite molecular sieve prepared in example 1.
FIG. 2 is an SEM image of a sample of an unfired titanium silicalite molecular sieve prepared in comparative example 1.
FIG. 3 is the HAADF-STEM diagram and the particle size distribution diagram of the catalyst prepared in example 1.
FIG. 4 is a HAADF-STEM diagram and a particle size distribution diagram of the catalyst prepared in comparative example 1.
FIG. 5 is a graph comparing the results of catalytic activity in the oxyhydrogen epoxidation reaction of propylene for the catalysts prepared in example 1 and comparative example 1.
Detailed Description
The technical solution of the present invention is clearly and completely described below with reference to specific embodiments. It is to be understood that the described embodiments are only a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without making creative efforts, fall within the scope of the invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers. Unless otherwise stated, room temperature means a temperature of 20-30 ℃.
Example 1
The Au-Ti bifunctional catalyst is prepared by taking urea as a precipitator, chloroauric acid as a gold precursor and freeze-dried unbaked TS-1 (namely TS-1-B) as a carrier, and comprises the following steps:
(1) Placing an unfired titanium silicalite TS-1-B sample in a freeze dryer, freezing for 2h at-4 ℃ in advance, and then vacuumizing (pressure 2 Pa) at-50 ℃ for freeze drying for 48h.
(2) Putting 1g of freeze-dried TS-1-B molecular sieve in a 100ml beaker, adding 39ml of water, 1ml of chloroauric acid aqueous solution and 0.09g of urea, stirring in a water bath kettle at 90 ℃ in the dark for 6 hours, transferring the suspension into a centrifuge tube, centrifuging twice at 6000 rpm, and washing the catalyst sample by using ultrapure water after each centrifugation. The obtained catalyst was placed in a room temperature vacuum desiccator and dried overnight in the dark to obtain a catalyst precursor.
(3) And (2) placing the dried catalyst precursor in a fixed bed reactor, and heating to 300 ℃ at the speed of 1 ℃/min from room temperature for 100min under the conditions that the hydrogen/nitrogen =2:3 (volume ratio) and the gas flow rate is 50mL/min to obtain the supported Au-Ti bifunctional catalyst, wherein the loading capacity of gold is 0.09wt%.
Comparative example 1
The Au-Ti bifunctional catalyst is prepared by taking urea as a precipitator, chloroauric acid as a gold precursor and unbaked TS-1 (namely TS-1-B) dried by a high-temperature oven as a carrier, and comprises the following steps:
(1) Placing an unfired titanium silicalite TS-1-B sample in an oven, and then drying in static air at 60 ℃ for 12h.
(2) Putting 1g of TS-1-B molecular sieve dried by a high-temperature oven into a 100ml beaker, adding 39ml of water, 1ml of chloroauric acid aqueous solution and 0.09g of urea, stirring for 6 hours in a water bath kettle at 90 ℃ in a dark place, transferring the suspension into a centrifuge tube, centrifuging twice at 6000 rpm, and washing the catalyst sample by using ultrapure water after each centrifugation. The obtained catalyst was placed in a room temperature vacuum desiccator and dried overnight in the dark to obtain a catalyst precursor.
(3) And (2) placing the dried catalyst precursor in a fixed bed reactor, heating to 300 ℃ from room temperature at the speed of 1 ℃/min under the conditions of hydrogen/nitrogen =2:3 (volume ratio) and gas flow rate of 50mL/min, and keeping for 100min to obtain the supported Au-Ti bifunctional catalyst, wherein the loading capacity of gold is 0.09wt%.
SEM characterization is performed on the TS-1-B titanium silicalite molecular sieve samples prepared in the step (1) of the example 1 and the comparative example 1, and the corresponding characterization results are respectively shown in FIG. 1 and FIG. 2, the comparative example 1 has aggregates with a significantly larger size, compared with the comparative example 1, the size of the aggregates of the titanium silicalite molecular sieve prepared by freeze drying in the example 1 is significantly smaller than that of the titanium silicalite molecular sieve prepared by high temperature drying in a traditional oven, which means that the dispersity of the freeze-dried TS-1-B molecular sieve particles is significantly improved.
HAADF-STEM characterization was performed on the gold catalysts prepared in example 1 and comparative example 1, and the corresponding characterization results are shown in FIG. 3 and FIG. 4, respectively, compared with comparative example 1, the gold catalysts prepared in example 1 using freeze-dried TS-1-B as a carrier and supported on gold had smaller particle sizes of gold nanoparticles.
Example 2
The gold catalysts prepared in the above example 1 and comparative example 1 were used to evaluate the catalytic performance in the reaction of propylene oxide preparation by oxyhydrogen epoxidation, the propylene gas phase epoxidation reaction was carried out in a fixed bed reactor at normal pressure, and the reaction atmosphere consisted of propylene: hydrogen gas: oxygen: nitrogen =1:1:1:7 (volume ratio) and the space velocity of 14000 mL.h -1 ·g cat -1 The outlet product was analyzed by gas chromatography. The catalytic reaction results are shown in table 1 and fig. 5.
TABLE 1 evaluation of catalyst Performance
As can be seen from the results of table 1 and fig. 5, the uncalcined titanium silicalite TS-1-B supported gold catalyst prepared in example 1 by freeze-drying has higher hydrogen utilization rate and higher PO formation rate, i.e., higher catalytic activity, for the reaction of preparing propylene oxide by oxyhydrogen epoxidation compared with the uncalcined titanium silicalite TS-1-B supported gold catalyst prepared in comparative example 1 by drying.
Claims (10)
1. A method for improving dispersity of gold nanoparticles on a gold catalyst supported by a titanium-silicon molecular sieve is characterized in that a freeze-dried unfired titanium-silicon molecular sieve is used as a carrier, and a gold precursor solution, a precipitator and the freeze-dried unfired titanium-silicon molecular sieve are mixed, dried and activated to obtain the gold catalyst supported by the titanium-silicon molecular sieve.
2. The process of claim 1, wherein the uncalcined titanium silicalite molecular sieve comprises one or more of Ti-SBA-15, ti-MCM-41, ti-MCM-48, ti-MCM-36, ti-MWW, ti-MOR, ti-Beta, ti-TUD-1, TS-1, hierarchical pore TS-1, TS-2, and hierarchical pore TS-2.
3. The method of claim 1, wherein the non-calcined titanium silicalite molecular sieve is freeze-dried at a temperature of-80 to 0 ℃, preferably-50 to 0 ℃.
4. The method of claim 1, wherein the uncalcined titanium silicalite molecular sieve is pre-frozen at-10 to 0 ℃ for 2 to 8 hours prior to freeze drying.
5. The method of claim 1, wherein the uncalcined titanium silicalite molecular sieve is freeze-dried for 24 to 96 hours, preferably 36 to 48 hours.
6. The method according to claim 1, wherein the gold precursor in the gold precursor solution is selected from one or more of chloroauric acid, sodium chloroaurate, potassium chloroaurate, cesium chloroaurate, lithium chloroaurate, or ammonium chloroaurate; the precipitant is selected from MOH and M 2 CO 3 And one or more of urea and ammonia water, wherein M is Li, na, K, rb or Cs.
7. The method according to claim 1, characterized in that the activation treatment is carried out in the presence of an activating atmosphere, which is air, a reducing atmosphere or an inert atmosphere; the activation temperature is 150 to 400 ℃, preferably 200 to 350 ℃, more preferably 300 to 320 ℃.
8. A titanium silicalite supported gold catalyst prepared by the method of any one of claims 1 to 7.
9. The titanium silicalite supported gold catalyst of claim 8, wherein the particle size of the gold nanoparticles on the titanium silicalite supported gold catalyst is less than 5nm, preferably less than 2.5nm.
10. The use of the titanium silicalite molecular sieve-supported gold catalyst according to claim 8 or 9, characterized in that the catalyst is used in the reaction of producing propylene oxide by oxyhydrogen epoxidation of propylene.
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| CN202211026338.5A CN115283011A (en) | 2022-08-25 | 2022-08-25 | Method for improving dispersity of gold nanoparticles of titanium-silicon molecular sieve supported gold catalyst and application of gold nanoparticles |
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| CN202211026338.5A CN115283011A (en) | 2022-08-25 | 2022-08-25 | Method for improving dispersity of gold nanoparticles of titanium-silicon molecular sieve supported gold catalyst and application of gold nanoparticles |
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| US20100234623A1 (en) * | 2009-03-13 | 2010-09-16 | Tokyo Metropolitan University | Method for producing propylene oxide |
| CN103395799A (en) * | 2013-08-07 | 2013-11-20 | 华东理工大学 | Preparation method for titanium silicalite molecular sieve and applications |
| CN105363436A (en) * | 2014-08-27 | 2016-03-02 | 中国石油化工股份有限公司 | Carbon monoxide gas phase coupling oxalate synthesis catalyst and preparation method and application thereof |
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| US20100234623A1 (en) * | 2009-03-13 | 2010-09-16 | Tokyo Metropolitan University | Method for producing propylene oxide |
| CN103395799A (en) * | 2013-08-07 | 2013-11-20 | 华东理工大学 | Preparation method for titanium silicalite molecular sieve and applications |
| CN105363436A (en) * | 2014-08-27 | 2016-03-02 | 中国石油化工股份有限公司 | Carbon monoxide gas phase coupling oxalate synthesis catalyst and preparation method and application thereof |
Non-Patent Citations (1)
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| 钱泽朋等: "多孔负载型纳米金属催化剂制备研究进展", 应用化工, vol. 50, no. 6, 30 June 2021 (2021-06-30), pages 1699 - 1703 * |
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