CN116078400B - Supported gold-based catalyst, preparation method thereof and application thereof in preparation of carboxylic ester by aldehyde oxidation and esterification under low alcohol-aldehyde ratio - Google Patents
Supported gold-based catalyst, preparation method thereof and application thereof in preparation of carboxylic ester by aldehyde oxidation and esterification under low alcohol-aldehyde ratio Download PDFInfo
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- CN116078400B CN116078400B CN202310034424.9A CN202310034424A CN116078400B CN 116078400 B CN116078400 B CN 116078400B CN 202310034424 A CN202310034424 A CN 202310034424A CN 116078400 B CN116078400 B CN 116078400B
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- 239000010931 gold Substances 0.000 title claims abstract description 159
- 239000003054 catalyst Substances 0.000 title claims abstract description 158
- 229910052737 gold Inorganic materials 0.000 title claims abstract description 156
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title claims abstract description 155
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 150000001299 aldehydes Chemical class 0.000 title claims abstract description 10
- 150000001733 carboxylic acid esters Chemical class 0.000 title claims abstract description 8
- 230000003647 oxidation Effects 0.000 title abstract description 10
- 238000007254 oxidation reaction Methods 0.000 title abstract description 10
- 238000005886 esterification reaction Methods 0.000 title abstract description 9
- 230000032050 esterification Effects 0.000 title abstract description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 78
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 77
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 77
- 229910052783 alkali metal Inorganic materials 0.000 claims abstract description 72
- 150000001340 alkali metals Chemical class 0.000 claims abstract description 58
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 45
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 34
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000000126 substance Substances 0.000 claims abstract description 28
- 229910000272 alkali metal oxide Inorganic materials 0.000 claims abstract description 9
- 239000010410 layer Substances 0.000 claims description 96
- 229910052760 oxygen Inorganic materials 0.000 claims description 37
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 33
- 239000001301 oxygen Substances 0.000 claims description 33
- 238000002156 mixing Methods 0.000 claims description 28
- 229910005855 NiOx Inorganic materials 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 239000007788 liquid Substances 0.000 claims description 24
- 150000002815 nickel Chemical class 0.000 claims description 24
- 239000002243 precursor Substances 0.000 claims description 24
- 239000007787 solid Substances 0.000 claims description 24
- 239000007789 gas Substances 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 17
- 238000000926 separation method Methods 0.000 claims description 17
- 238000006722 reduction reaction Methods 0.000 claims description 15
- 238000010304 firing Methods 0.000 claims description 14
- 239000006185 dispersion Substances 0.000 claims description 13
- 229920000620 organic polymer Polymers 0.000 claims description 10
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 9
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 9
- 239000002105 nanoparticle Substances 0.000 claims description 7
- 239000004215 Carbon black (E152) Substances 0.000 claims description 6
- 150000008044 alkali metal hydroxides Chemical class 0.000 claims description 6
- 229930195733 hydrocarbon Natural products 0.000 claims description 6
- 150000002430 hydrocarbons Chemical class 0.000 claims description 6
- 229910000288 alkali metal carbonate Inorganic materials 0.000 claims description 5
- 150000008041 alkali metal carbonates Chemical class 0.000 claims description 5
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 5
- 239000002041 carbon nanotube Substances 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims description 4
- 229910001948 sodium oxide Inorganic materials 0.000 claims description 4
- 229910003481 amorphous carbon Inorganic materials 0.000 claims description 3
- CHWRSCGUEQEHOH-UHFFFAOYSA-N potassium oxide Chemical compound [O-2].[K+].[K+] CHWRSCGUEQEHOH-UHFFFAOYSA-N 0.000 claims description 3
- 229910001950 potassium oxide Inorganic materials 0.000 claims description 3
- 239000002344 surface layer Substances 0.000 claims description 3
- 238000006709 oxidative esterification reaction Methods 0.000 claims description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 12
- HSJKGGMUJITCBW-UHFFFAOYSA-N 3-hydroxybutanal Chemical compound CC(O)CC=O HSJKGGMUJITCBW-UHFFFAOYSA-N 0.000 abstract description 10
- STNJBCKSHOAVAJ-UHFFFAOYSA-N Methacrolein Chemical compound CC(=C)C=O STNJBCKSHOAVAJ-UHFFFAOYSA-N 0.000 abstract description 7
- 239000002244 precipitate Substances 0.000 description 32
- 238000006243 chemical reaction Methods 0.000 description 20
- 239000000243 solution Substances 0.000 description 17
- 238000010438 heat treatment Methods 0.000 description 16
- 230000003197 catalytic effect Effects 0.000 description 15
- 239000000047 product Substances 0.000 description 14
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 12
- -1 alkali metal salt Chemical class 0.000 description 12
- 238000001914 filtration Methods 0.000 description 12
- 238000003756 stirring Methods 0.000 description 11
- 230000008569 process Effects 0.000 description 9
- 229910003297 Ni(NO3)3·6H2O Inorganic materials 0.000 description 8
- 229910003158 γ-Al2O3 Inorganic materials 0.000 description 8
- 239000002253 acid Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 238000001291 vacuum drying Methods 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 239000004372 Polyvinyl alcohol Substances 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000001035 drying Methods 0.000 description 6
- 229920002451 polyvinyl alcohol Polymers 0.000 description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 description 6
- VQTUBCCKSQIDNK-UHFFFAOYSA-N Isobutene Chemical group CC(C)=C VQTUBCCKSQIDNK-UHFFFAOYSA-N 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 5
- 239000012265 solid product Substances 0.000 description 5
- 238000009210 therapy by ultrasound Methods 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 238000001354 calcination Methods 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 4
- LELOWRISYMNNSU-UHFFFAOYSA-N hydrogen cyanide Chemical compound N#C LELOWRISYMNNSU-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 239000003223 protective agent Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 238000004969 ion scattering spectroscopy Methods 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 2
- 239000004926 polymethyl methacrylate Substances 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000001132 ultrasonic dispersion Methods 0.000 description 2
- MWFMGBPGAXYFAR-UHFFFAOYSA-N 2-hydroxy-2-methylpropanenitrile Chemical compound CC(C)(O)C#N MWFMGBPGAXYFAR-UHFFFAOYSA-N 0.000 description 1
- QLDHWVVRQCGZLE-UHFFFAOYSA-N acetyl cyanide Chemical compound CC(=O)C#N QLDHWVVRQCGZLE-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 230000001012 protector Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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
- 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
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/8946—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali or alkaline earth 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
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/39—Preparation of carboxylic acid esters by oxidation of groups which are precursors for the acid moiety of the ester
-
- 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
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
Abstract
The invention belongs to the technical field of gold-based catalysts, and particularly relates to a supported gold-based catalyst, a preparation method thereof and application thereof in preparing carboxylic ester by aldehyde oxidation and esterification under low alcohol-aldehyde ratio. The supported gold-based catalyst provided by the invention comprises a gamma alumina carrier, an active component and a carbon simple substance, wherein the active component and the carbon simple substance are supported on the gamma alumina carrier; the active component consists of a gold simple substance, an alkali metal oxide, a nickel simple substance and oxides thereof; the molar ratio of the aluminum element to the alkali metal element to the gold element to the nickel element to the carbon element is 1 (0.0016-0.0164), 0.0018-0.0031, 0.0061-0.0130 and 0.0425-0.0850. The supported gold-based catalyst provided by the invention has the advantages of hydrophobization, high activity and high stability, and can be used for converting methacrolein into methyl methacrylate with high activity and high stability under the condition of low aldol ratio.
Description
Technical Field
The invention belongs to the technical field of gold-based catalysts, and particularly relates to a supported gold-based catalyst, a preparation method thereof and application thereof in preparing carboxylic ester by aldehyde oxidation and esterification under low alcohol-aldehyde ratio.
Background
Methyl Methacrylate (MMA) is used as a basic chemical raw material, can be applied to the production of polymethyl methacrylate (PMMA), and is widely applied to various fields such as construction, medicine, paint, military industry and the like. Since the 50 s of the 20 th century, china began to carry out large-scale industrial production, and along with the rapid development of economy, the global demand for MMA has been greatly increased.
At present, the world MMA production processes mainly include a pyruvonitrile alcohol process (ACH process), an isobutylene process and an ethylene process. In global MMA production capacity, the acetone cyanohydrin method accounts for 83%, the isobutene method accounts for 16% and the ethylene method accounts for 1%. The ACH method has the characteristics of simple process and high maturity, but raw material hydrocyanic acid used in the method is extremely toxic, hydrocyanic acid and sulfuric acid have strong corrosiveness, the requirements on reaction equipment are high, and the discharge amount of waste acid is large, so that the method can cause great harm to the environment. The two-step isobutene process is a simple, green and economical process route with economic competitiveness, and has no methacrylic acid in the middle, so that the production cost is greatly saved, but in the process of producing MMA by converting Methacrylic Acid (MAL), the first generation Pd-Pb catalyst is too low in environmental protection and large in dosage due to Pb element, so that the development of a new generation efficient green catalyst is still needed.
Among them, au-based catalysts have been slowly paid attention to by many researchers due to their excellent catalytic performance, but in the existing researches, the ratio of aldol is too high (molar ratio is 40 or more) during the catalytic reaction of Au-based catalysts, and a large amount of energy is required for the subsequent separation and recovery of methanol, which is not beneficial to industrial application.
Disclosure of Invention
The invention aims to provide a supported gold-based catalyst, a preparation method thereof and application thereof in preparing carboxylic ester by oxidizing and esterifying aldehydes under a low aldol ratio.
In order to achieve the above object, the present invention provides the following technical solutions:
The invention provides a supported gold-based catalyst, which comprises a gamma alumina carrier, an active component and a carbon simple substance, wherein the active component and the carbon simple substance are supported on the gamma alumina carrier; the active component consists of a gold simple substance, an alkali metal oxide, a nickel simple substance and a nickel oxide thereof;
The molar ratio of aluminum element to alkali metal element in the supported gold-based catalyst is 1 (0.0016-0.0164);
The molar ratio of aluminum element to gold element in the supported gold-based catalyst is 1 (0.0018-0.0031);
The molar ratio of aluminum element to nickel element in the supported gold-based catalyst is 1 (0.0061-0.0130);
The molar ratio of aluminum element to carbon element in the supported gold-based catalyst is 1 (0.0425-0.0850).
Preferably, the simple substance nickel and the nickel oxide thereof are present on the surface of the supported gold-based catalyst at 1.2nm or less.
Preferably, the surface layer of the supported gold-based catalyst sequentially comprises a first layer structure, a second layer structure, a third layer structure and a fourth layer structure from outside to inside;
The first layer structure comprises aluminum element, gold element, carbon element, oxygen element and alkali metal element; the mass percentage of aluminum element in the first layer structure is 46.3-46.6%, the mass percentage of gold element in the first layer structure is 18.1-18.4%, the mass percentage of carbon element and oxygen element in the first layer structure is 29.4-29.7%, and the mass percentage of alkali metal element in the first layer structure is 5.6-5.9%;
the second layer structure comprises aluminum element, gold element, carbon element, oxygen element and alkali metal element; the mass percentage of aluminum element in the second layer structure is 46.9-47.2%, the mass percentage of gold element in the second layer structure is 17.5-17.8%, the mass percentage of carbon element and oxygen element in the second layer structure is 29.7-30.0%, and the mass percentage of alkali metal element in the second layer structure is 5.3-5.6%;
The third layer structure comprises aluminum element, gold element, carbon element, oxygen element, alkali metal element and nickel element; the mass percentage of aluminum element in the third layer structure is 44.4-45.8%, the mass percentage of gold element in the third layer structure is 19.8-20.8%, the mass percentage of carbon element and oxygen element in the third layer structure is 26.4-27.2%, and the mass percentage of alkali metal element in the third layer structure is 5.6-5.9%; the mass percentage of nickel element in the third layer structure is 1.3-2.9%;
The fourth layer structure comprises aluminum element, gold element, carbon element, oxygen element, alkali metal element and nickel element; the mass percentage of aluminum element in the fourth layer structure of the core is 46.7-49.1%, the mass percentage of gold element in the fourth layer structure is 19.0-19.3%, the mass percentage of carbon element and oxygen element in the fourth layer structure is 24.9-25.2%, and the mass percentage of alkali metal element in the fourth layer structure is 5.2-7.2%; the mass percentage of nickel element in the fourth layer structure is 1.8-2.4%.
Preferably, the thicknesses of the first layer structure, the second layer structure, the third layer structure and the fourth layer structure are all 0.6nm.
Preferably, jin Shanzhi is spherical gold nanoparticle, and the particle size of the spherical gold nanoparticle is 3-8 nm.
Preferably, the elemental carbon comprises one or more of amorphous carbon, graphitic carbon, and carbon nanotubes.
Preferably, the alkali metal oxide comprises sodium oxide and/or potassium oxide.
The invention provides a preparation method of the supported gold-based catalyst, which comprises the following steps:
mixing water-soluble nickel salt, water and gamma alumina carrier to obtain nickel salt dispersion system;
Mixing the nickel salt dispersion system with an alkali metal source, and carrying out solid-liquid separation to obtain a first solid precursor; the alkali metal source includes alkali metal hydroxide and alkali metal carbonate;
first roasting the first solid precursor to obtain a first roasting product;
Carrying out reduction reaction on the first roasting product in reducing gas to obtain a supported alkali metal oxide-nickel catalyst;
mixing the supported alkali metal oxide-nickel catalyst, a water-soluble gold source, an organic polymer and water, and standing for solid-liquid separation to obtain a second solid precursor;
Second roasting the second solid precursor to obtain a supported gold-alkali metal oxide-NiOx catalyst;
Thirdly roasting the supported gold-alkali metal oxide-NiOx catalyst in a reducing gas containing a carbon source to obtain the supported gold-based catalyst; the carbon source is a gaseous hydrocarbon.
Preferably, the temperature of the first roasting is 400-450 ℃; the temperature of the reduction reaction is 600-650 ℃; the temperature of the second roasting is 300-350 ℃, and the temperature of the third roasting is 750-900 ℃.
The invention provides an application of the supported gold-based catalyst in the technical scheme or the supported gold-based catalyst prepared by the preparation method in preparation of carboxylic ester by aldehyde oxidation and esterification under low alcohol-aldehyde ratio.
The invention provides a supported gold-based catalyst, which comprises a gamma alumina carrier, an active component and a carbon simple substance, wherein the active component and the carbon simple substance are supported on the gamma alumina carrier; the active component consists of a gold simple substance, an alkali metal oxide, a nickel simple substance and a nickel oxide thereof; the molar ratio of aluminum element to alkali metal element in the supported gold-based catalyst is 1 (0.0016-0.0164); the molar ratio of aluminum element to gold element in the supported gold-based catalyst is 1 (0.0018-0.0031); the molar ratio of aluminum element to nickel element in the supported gold-based catalyst is 1 (0.0061-0.0130); the molar ratio of aluminum element to carbon element in the supported gold-based catalyst is 1 (0.0425-0.0850). The addition of the alkali metal element protects the alkaline site of the supported gold-based catalyst, and is also beneficial to attaching carbon elements on the periphery of the gold metal active site of the supported gold-based catalyst; the addition of the carbon simple substance improves the hydrophobicity of the supported gold-based catalyst, so that the catalyst deactivation caused by water in the catalytic reaction is avoided, and the catalytic life of the supported gold-based catalyst is prolonged; meanwhile, the nickel element is added into the gold-based catalyst, so that the agglomeration growth of the gold simple substance is inhibited, the surface area of the gold simple substance is increased, the catalytic activity of the gold simple substance is improved, and meanwhile, the gold simple substance is protected from being reduced in the catalytic process under the condition of low alcohol-aldehyde ratio, so that the catalytic life of the supported gold-based catalyst is prolonged, the alkalescent sites of the catalyst IDE can be enhanced, and the catalytic activity of the catalyst is improved; the supported gold-based catalyst provided by the invention has the advantages of hydrophobization, high activity and high stability, and can realize high activity and high stability under the condition of low aldol ratio to convert methacrolein into methyl methacrylate.
Further, in the present invention, the elemental nickel and its nickel oxide are present on the surface of the supported gold-based catalyst at 1.2nm or less. The nickel element of the supported gold-based catalyst provided by the invention exists below 1.2nm on the surface of the supported gold-based catalyst, so that the phenomenon that the activity of the catalyst is reduced due to the fact that the alkalinity of the surface of the catalyst is too strong and the occurrence of side reactions is increased can be avoided.
The invention provides a preparation method of the supported gold-based catalyst, which comprises the following steps: mixing water-soluble nickel salt, water and gamma alumina carrier to obtain nickel salt dispersion system; mixing the nickel salt dispersion system with an alkali metal source, and carrying out solid-liquid separation to obtain a first solid precursor; the alkali metal source includes alkali metal hydroxide and alkali metal carbonate; first roasting the first solid precursor to obtain a first roasting product; carrying out reduction reaction on the first roasting product in reducing gas to obtain a supported alkali metal oxide-nickel catalyst; mixing the supported alkali metal oxide-nickel catalyst, a water-soluble gold source, an organic polymer and water, and standing for solid-liquid separation to obtain a second solid precursor; second roasting the second solid precursor to obtain a supported gold-alkali metal oxide-NiOx catalyst; thirdly roasting the supported gold-alkali metal oxide-NiOx catalyst in a reducing gas containing a carbon source to obtain the supported gold-based catalyst; the carbon source is a gaseous hydrocarbon. The preparation method provided by the invention is simple and feasible, and is suitable for industrial production.
Drawings
FIG. 1 is an XRD pattern of a supported gold-based catalyst prepared in example 1 of the present invention;
FIG. 2 is a TEM image of the supported gold-based catalyst prepared in example 1 of the present invention;
FIG. 3 is a low energy ion scattering spectrum of the supported gold-based catalyst prepared in example 1 of the present invention;
FIG. 4 is a graph showing the comparison of catalytic performances of the supported gold-based catalysts prepared in examples 1 to 4 of the present invention.
Detailed Description
The invention provides a supported gold-based catalyst, which comprises a gamma alumina carrier, an active component and a carbon simple substance, wherein the active component and the carbon simple substance are supported on the gamma alumina carrier; the active component consists of a gold simple substance, an alkali metal oxide, a nickel simple substance and a nickel oxide thereof;
The molar ratio of aluminum element to alkali metal element in the supported gold-based catalyst is 1 (0.0016-0.0164);
The molar ratio of aluminum element to gold element in the supported gold-based catalyst is 1 (0.0018-0.0031);
The molar ratio of aluminum element to nickel element in the supported gold-based catalyst is 1 (0.0061-0.0130);
The molar ratio of aluminum element to carbon element in the supported gold-based catalyst is 1 (0.0425-0.0850).
In the present invention, all preparation materials/components are commercially available products well known to those skilled in the art unless specified otherwise.
The supported gold-based catalyst provided by the invention comprises a gamma alumina carrier. The gamma alumina is used as a carrier of the supported gold-based catalyst, has a porous structure and can effectively support active components of the catalyst.
The supported gold-based catalyst provided by the invention comprises an active component and a carbon simple substance which are supported on the gamma alumina carrier.
In the present invention, the active components are elemental gold, alkali metal oxides, elemental nickel, and nickel oxides.
In the present invention, the alkali metal oxide includes sodium oxide and/or potassium oxide, and more preferably sodium oxide.
In the present invention, the carbon element includes one or more of amorphous carbon, graphitic carbon, or carbon nanotubes, and more preferably carbon nanotubes.
In the present invention, the molar ratio of the aluminum element to the alkali metal element in the supported gold-based catalyst is 1 (0.0016 to 0.0164), preferably 1 (0.0018 to 0.016).
In the invention, the molar ratio of the aluminum element to the gold element in the supported gold-based catalyst is 1 (0.0018-0.0031), preferably 1 (0.002-0.003)
In the present invention, the molar ratio of the aluminum element to the nickel element in the supported gold-based catalyst is 1 (0.0061 to 0.0130), preferably 1 (0.008 to 0.01).
In the invention, the molar ratio of aluminum element to carbon element in the supported gold-based catalyst is 1 (0.0425-0.0850), preferably 1 (0.045-0.08).
In the present invention, the elemental nickel and its nickel oxide are preferably present on the surface of the supported gold-based catalyst at 1.2nm or less.
In the present invention, the surface layer of the supported gold-based catalyst preferably comprises a first layer structure, a second layer structure, a third layer structure and a fourth layer structure from outside to inside.
In the present invention, the first layer structure preferably includes an aluminum element, a gold element, a carbon element, an oxygen element, and an alkali metal element; the mass percentage of aluminum element in the first layer structure is preferably 46.3-46.6%, the mass percentage of gold element in the first layer structure is preferably 18.1-18.4%, the mass percentage of carbon element and oxygen element in the first layer structure is preferably 29.4-29.7%, and the mass percentage of alkali metal element in the first layer structure is preferably 5.6-5.9%.
In the present invention, the thickness of the first layer structure is preferably 0.6nm.
In the present invention, the second layer structure preferably includes an aluminum element, a gold element, a carbon element, an oxygen element, and an alkali metal element; the mass percentage of aluminum element in the second layer structure is preferably 46.9-47.2%, the mass percentage of gold element in the second layer structure is preferably 17.5-17.8%, the mass percentage of carbon element and oxygen element in the second layer structure is preferably 29.7-30.0%, and the mass percentage of alkali metal element in the second layer structure is preferably 5.3-5.6%.
In the present invention, the thickness of the second layer structure is preferably 0.6nm.
In the present invention, the third layer structure preferably includes an aluminum element, a gold element, a carbon element, an oxygen element, an alkali metal element, and a nickel element; the mass percentage of aluminum element in the third layer structure is preferably 44.4-45.8%, the mass percentage of gold element in the third layer structure is preferably 19.8-20.8%, the mass percentage of carbon element and oxygen element in the third layer structure is preferably 26.4-27.2%, and the mass percentage of alkali metal element in the third layer structure is preferably 5.6-5.9%; the mass percentage of nickel element in the third layer structure is preferably 1.3-2.9%.
In the present invention, the thickness of the third layer structure is preferably 0.6nm.
In the present invention, the fourth layer structure preferably includes an aluminum element, a gold element, a carbon element, an oxygen element, an alkali metal element, and a nickel element; the mass percentage of aluminum element in the fourth layer structure of the core is preferably 46.7-49.1%, the mass percentage of gold element in the fourth layer structure is preferably 19.0-19.3%, the mass percentage of carbon element and oxygen element in the fourth layer structure is preferably 24.9-25.2%, and the mass percentage of alkali metal element in the fourth layer structure is preferably 5.2-7.2%; the mass percentage of nickel element in the fourth layer structure is preferably 1.8-2.4%.
In the present invention, the thickness of the fourth layer structure is preferably 0.6nm.
In the invention, the content of nickel and gold elements is increased and the content of carbon and gamma alumina is decreased as the load-type gold-based catalyst goes deep from outside to inside, which indicates that the carbon better realizes hydrophobicity and sintering resistance on the surface coated with the catalyst, and the interaction between Au and Ni under C greatly improves the stability of the catalyst.
In the invention, jin Shanzhi is spherical gold nanoparticle, and the particle size of the spherical gold nanoparticle is 3-8 nm.
The invention provides a preparation method of the supported gold-based catalyst, which comprises the following steps:
mixing water-soluble nickel salt, water and gamma alumina carrier to obtain nickel salt dispersion system;
Mixing the nickel salt dispersion system with an alkali metal source, and carrying out solid-liquid separation to obtain a first solid precursor; the alkali metal source includes alkali metal hydroxide and alkali metal carbonate;
first roasting the first solid precursor to obtain a first roasting product;
Carrying out reduction reaction on the first roasting product in reducing gas to obtain a supported alkali metal oxide-nickel catalyst;
mixing the supported alkali metal oxide-nickel catalyst, a water-soluble gold source, an organic polymer and water, and standing for solid-liquid separation to obtain a second solid precursor;
Second roasting the second solid precursor to obtain a supported gold-alkali metal oxide-NiOx catalyst;
Thirdly roasting the supported gold-alkali metal oxide-NiOx catalyst in a reducing gas containing a carbon source to obtain the supported gold-based catalyst; the carbon source is a gaseous hydrocarbon.
The present invention mixes a water-soluble nickel salt, water and a gamma alumina carrier (hereinafter referred to as a first mix) to obtain a nickel salt dispersion.
In the present invention, the water-soluble nickel salt is particularly preferably Ni (NO 3)3·6H2 O).
In the invention, the mass ratio of the water-soluble nickel salt to the gamma alumina carrier is preferably 0.3-0.4:1.
In the present invention, the first mixing preferably includes the steps of: dissolving the water-soluble nickel salt in water to obtain a water-soluble nickel salt solution; and mixing and dispersing the water-soluble nickel salt solution and the gamma alumina carrier. The invention has no special requirement on the dosage of the water, and ensures that the water-soluble nickel salt is completely dissolved. In the present invention, the mixing and dispersing preferably includes stirring and mixing and ultrasonic dispersing in this order; the temperature of the stirring and mixing is preferably 60 ℃, and the heat preservation time of the stirring and mixing is preferably 30min; the time of the ultrasonic dispersion is preferably 30 minutes.
After the nickel salt dispersion system is obtained, the nickel salt dispersion system and an alkali metal source are mixed (hereinafter referred to as second mixing), and solid-liquid separation (hereinafter referred to as first solid-liquid separation) is carried out to obtain a first solid precursor; the alkali metal source includes alkali metal hydroxide and alkali metal carbonate.
In the present invention, the alkali metal hydroxide preferably includes sodium hydroxide and/or potassium hydroxide, more preferably includes sodium hydroxide. In the present invention, the alkali metal salt acid salt preferably includes sodium carbonate and/or potassium carbonate, more preferably includes sodium carbonate.
In a specific embodiment of the present invention, the alkali metal source is particularly preferably sodium carbonate.
In the present invention, the alkali metal source is preferably used in the form of an aqueous solution of the alkali metal source at the time of the second mixing. In the present invention, the molar concentration of the alkali metal source aqueous solution is preferably 0.5mol/L.
In the present invention, the mass ratio of the water-soluble nickel salt to the alkali metal source is preferably 1:0.5 to 1.5.
The invention has no special requirements for the implementation of the second mixing.
In the present invention, the specific embodiment of the first solid-liquid separation is preferably filtration. In the present invention, the first solid-liquid separation is performed to obtain a solid product, and the solid product is preferably dried to obtain the first solid precursor. In the present invention, the drying is preferably vacuum drying, the temperature of the vacuum drying is preferably 55 ℃, and the time of the vacuum drying is preferably 12 hours.
After a first solid precursor is obtained, the first solid precursor is subjected to first roasting to obtain a first roasting product.
In the present invention, the first firing is preferably performed in a muffle furnace.
In the present invention, the temperature of the first firing is preferably 400 to 450 ℃, more preferably 400 ℃.
In the present invention, the holding time of the second firing is preferably 3 hours.
In the present invention, the temperature rising rate from the room temperature to the temperature of the first firing is preferably 2 ℃/min.
After the first roasting product is obtained, the first roasting product is subjected to reduction reaction in reducing gas to obtain the supported alkali metal oxide-nickel catalyst.
In the present invention, the reduction reaction is preferably carried out in a tube furnace.
In the present invention, the reducing gas is preferably hydrogen.
In the present invention, the temperature of the reduction reaction is preferably 600 to 650 ℃, more preferably 600 ℃.
In the present invention, the incubation time for the reduction reaction is preferably 4 hours.
In the present invention, the rate of temperature increase from room temperature to the temperature of the reduction reaction is preferably 2 ℃/min.
After the supported alkali metal oxide-nickel catalyst is obtained, the supported alkali metal oxide-nickel catalyst, a water-soluble gold source, an organic polymer and water are mixed (hereinafter referred to as third mixing), and solid-liquid separation (hereinafter referred to as second solid-liquid separation) is performed after standing, so that a second solid precursor is obtained.
In the present invention, the water-soluble gold source is particularly preferably chloroauric acid.
In the present invention, the organic polymer is particularly preferably polyvinyl alcohol (PVA). The present invention preferably uses the organic polymer as a protector to protect the gold element from oxidation during the second firing.
In the present invention, the mass ratio of the water-soluble gold source to the water-soluble nickel salt is preferably 0.02026 (0.058 to 0.581).
In the present invention, the mass ratio of the water-soluble gold source to the organic polymer is preferably 0.02026:0.01.
In the present invention, the third mixing preferably includes the steps of: dissolving the water-soluble gold source in part of water to obtain a gold source solution; ultrasonically dispersing the gold source solution, the organic polymer and the residual water to obtain a mixed dispersion liquid; mixing the mixed dispersion with the supported alkali metal oxide-nickel catalyst. In the present invention, the mass concentration of the gold source solution is preferably 1g/50mL. The time of the ultrasonic dispersion is preferably 10 minutes.
In the present invention, the time of the standing is preferably 6 hours.
The present invention has no special requirements for the specific embodiment of the second solid-liquid separation.
In the present invention, the second solid-liquid separation is performed to obtain a solid product, and the present invention preferably performs post-treatment on the solid product to obtain the second solid precursor. In the present invention, the post-treatment preferably includes: the solid product is sequentially washed with water and dried, and in the present invention, the drying time is preferably 10 hours.
After the second solid precursor is obtained, the second solid precursor is subjected to second roasting to obtain the supported gold-alkali metal oxide-NiOx catalyst.
In the present invention, the second firing is preferably performed in a muffle furnace.
In the present invention, the temperature of the second firing is preferably 300 to 350 ℃, more preferably 300 ℃.
In the present invention, the holding time of the second firing is preferably 3 hours.
In the present invention, the rate of temperature increase from room temperature to the temperature of the second firing is preferably 2 ℃/min.
After obtaining a supported gold-alkali metal oxide-NiOx catalyst, the invention carries out third roasting on the supported gold-alkali metal oxide-NiOx catalyst in reducing gas containing a carbon source to obtain the supported gold-based catalyst; the carbon source is a gaseous hydrocarbon.
In the present invention, the supported gold-alkali metal oxide-NiOx catalyst is preferably pre-calcined to remove the organic polymer on the surface of the supported gold-alkali metal oxide-NiOx catalyst before the third calcination is performed. In the present invention, the temperature of the pre-calcination is preferably 450 to 500 ℃, and the heat-preserving time of the pre-calcination is preferably 2 hours.
In the present invention, the carbon source is a gaseous hydrocarbon, preferably methane.
In the present invention, the reducing gas containing a carbon source specifically preferably includes a carbon source gas, hydrogen gas, and an inert gas; the inert gas is preferably argon.
In the present invention, the volume ratio of the carbon source gas, hydrogen gas and inert gas in the reducing gas containing a carbon source is preferably 3 to 5:13.1 to 14.0:1.
In the present invention, the third firing is preferably performed in a tube furnace.
In the present invention, the temperature of the third firing is preferably 750 to 900 ℃, more preferably 850 ℃.
The third calcination is preferably performed at 850 ℃, and the obtained carbon simple substance is preferably a carbon nanotube.
In the present invention, the holding time of the third firing is preferably 3 minutes.
In the present invention, the rate of temperature increase from room temperature to the temperature of the third firing is preferably 2 ℃/min.
The invention provides an application of the supported gold-based catalyst in the preparation of carboxylic ester by aldehyde oxidation and esterification.
In the present invention, the application preferably includes the steps of:
in oxidizing gas, liquid aldehyde compound, liquid alcohol compound and supported gold-based catalyst are mixed for catalytic oxidation esterification reaction to obtain carboxylate compound.
In the present invention, the liquid aldehyde compound is specifically preferably Methacrolein (MAL).
In the present invention, the liquid alcohol compound is preferably methanol.
In the present invention, the volume ratio of the liquid alcohol compound to the liquid aldehyde compound is preferably equal to or less than 20:1, and particularly preferably 3:1, 5:1, 8:1, 10:1 or 20:1.
In the present invention, the ratio of the liquid aldehyde compound to the mass of the supported gold-based catalyst is preferably 5mL (0.5-1) g.
In the present invention, the oxidizing gas is particularly preferably oxygen.
In the present invention, the space velocity of the oxidizing gas is preferably 20mL/min, and the pressure of the catalytic oxidative esterification reaction is preferably normal pressure. The temperature of the catalytic oxidation esterification reaction is preferably 60 ℃, and the heat preservation time of the catalytic oxidation esterification reaction is preferably 2h.
In the present invention, the carboxylic acid ester compound is particularly preferably Methyl Methacrylate (MMA).
The technical solutions provided by the present invention are described in detail below with reference to the drawings and examples for further illustrating the present invention, but they should not be construed as limiting the scope of the present invention.
Example 1
Adding 0.116g of Ni (NO 3)3·6H2 O) into water, stirring uniformly, adding a gamma alumina carrier, heating and stirring at 60 ℃ for 30min to enable the gamma alumina carrier to be fully dispersed, then adding a 0.5mol/L sodium carbonate aqueous solution, filtering to obtain a precipitate, placing the precipitate into a muffle furnace for vacuum drying for 12H at 55 ℃, placing the precipitate into the muffle furnace for roasting for 3H at 400 ℃, wherein the heating rate is 2 ℃/min during roasting, placing the precipitate into a tubular furnace, and reducing for 4H at 600 ℃ in an atmosphere of H 2 to obtain a Na-Ni catalyst, wherein the heating rate is 2 ℃/min during reduction;
adding 1.013mL of chloroauric acid solution with the concentration of 1g/50mL and 0.01g of protective agent (PVA) into water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, then adding Na-Ni catalyst, uniformly mixing the solution, standing for 6h, filtering to obtain a precipitate, washing and drying the precipitate for 10h, putting the precipitate into a muffle furnace, roasting the precipitate for 3h at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and roasting to obtain the Au-Na-NiOx catalyst;
And (3) roasting the Au-Na-NiOx catalyst to remove surface organic matters, then placing the catalyst in a tube furnace, roasting the catalyst for 30 minutes at 850 ℃ in CH 4、H2 and Ar atmosphere to load carbon tubes on the surface of the catalyst, and obtaining a supported gold-based catalyst, namely the Au-Na-NiO x-5-CNT/γ-Al2O3 catalyst.
FIG. 1 is an XRD pattern of a supported gold-based catalyst prepared in example 1 of the present invention; as can be seen from fig. 1: the support of this example is gamma alumina.
FIG. 2 is a TEM image of the supported gold-based catalyst prepared in example 1 of the present invention; as can be seen from fig. 2: in the Au-Na-NiO x-5-CNT/γ-Al2O3 catalyst prepared in the embodiment, jin Shanzhi is spherical gold nanoparticles, and the particle size of the spherical gold nanoparticles is 3-8 nm.
FIG. 3 is a low energy ion scattering spectrum of the supported gold-based catalyst prepared in example 1 of the present invention; as can be seen from fig. 3: the surface of the Au-Na-NiO x-5-CNT/γ-Al2O3 catalyst prepared in the embodiment is divided into four layers, the thickness of each layer is 0.6nm, the first layer of composition elements are Al, au, O and C, and Na, and the relative contents are 46.3-46.6%, 18.1-18.4%, 29.4-29.7% and 5.6-5.9% respectively. The second layer comprises the relative contents of Al, au, O and C, na of 46.9-47.2%, 17.5-17.8%, 29.7-30.0% and 5.3-5.6% respectively; the third layer comprises Al, au, O, C, na and Ni, and the relative contents of the Al, the Au, the O, the C, the Na and the Ni are 44.4 to 45.8 percent, 19.8 to 20.8 percent, 26.4 to 27.2 percent, 5.6 to 5.9 percent and 1.3 to 2.9 percent respectively; the fourth layer contains Al, au, O and C, na and Ni in the relative content of 46.7-49.1%, 19.0-19.3%, 24.9-25.2%, 5.2-7.2% and 1.8-2.4%.
Example 2
The preparation process was essentially the same as in example 1, except that: ni (NO 3)3·6H2 O mass was changed to 0.058g to give a supported gold-based catalyst, designated Au-Na-NiO x-1-CNT/γ-Al2O3 catalyst.
Example 3
The preparation process was essentially the same as in example 1, except that: ni (NO 3)3·6H2 O mass was changed to 0.174g to obtain a supported gold-based catalyst, which was designated as Au-Na-NiO x-3-CNT/γ-Al2O3 catalyst.
Example 4
The preparation process was essentially the same as in example 1, except that: ni (NO 3)3·6H2 O mass was changed to 0.581 g) to obtain a supported gold-based catalyst, which was designated as Au-Na-NiO x-10-CNT/γ-Al2O3 catalyst.
Application example 1
40ML of CH 3 OH and 5mL of mLMAL are added into a three-necked flask, then 1g of Au-Na-NiO x-CNT/γ-Al2O3 catalyst prepared in examples 1-4 is respectively put into the three-necked flask, industrial oxygen is introduced into the three-necked flask for reaction, the reaction temperature is 60 ℃, the oxygen airspeed is 20mL/min, the reaction pressure is normal pressure, and the target product MMA is obtained after the reaction for 2h by filtration. The number of reactions was 2. The filtered reaction product was quantitatively analyzed by a SHIMADZU GC2010 type gas chromatograph.
FIG. 4 is a graph showing the comparison of catalytic performances of the supported gold-based catalysts prepared in examples 1 to 4 of the present invention.
As can be seen from fig. 4: with the increase of Ni content, the activity of the catalyst is increased and then reduced, because the excessive Ni content causes the over-strong alkalinity and increases the occurrence of side reaction, thereby causing the activity to be reduced, and the catalyst can still keep high activity under the long-time reaction under the condition of low alcohol-aldehyde ratio, which indicates that the catalyst has good stability. And with the addition of Ni content, the alkalescent site of the catalyst is gradually enhanced, and the reaction is well promoted.
Comparative example 1
Adding 0.116g of Ni (NO 3)3·6H2 O) into water, stirring uniformly, adding a gamma alumina carrier, heating and stirring at 60 ℃ for 30min, fully dispersing, performing ultrasonic treatment for 30min, filtering to obtain a precipitate, placing the precipitate into a 55 ℃ for vacuum drying for 12H, placing the precipitate into a muffle furnace for roasting for 3H at 400 ℃, heating up at 2 ℃/min, placing the precipitate into a tube furnace, and reducing for 4H at 600 ℃ under H 2 atmosphere to obtain a Ni catalyst, wherein the heating up rate during reduction is 2 ℃/min;
adding 1.013mL of chloroauric acid solution with the concentration of 1g/50mL and 0.01g of protective agent (PVA) into water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, then adding a Ni catalyst, uniformly mixing the solution, standing for 6h, filtering to obtain a precipitate, washing and drying the precipitate for 10h, putting the precipitate into a muffle furnace, roasting the precipitate for 3h at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and roasting to obtain the Au-NiOx catalyst;
Application example 2
40ML of CH 3 OH and 5mL of mLMAL are added into a three-necked flask, then 0.5g of the supported gold-based catalyst prepared in the example 1 and the supported gold-based catalyst prepared in the comparative example 1 are respectively placed into the three-necked flask, industrial oxygen is introduced into the three-necked flask for reaction, the reaction temperature is 60 ℃, the oxygen airspeed is 20mL/min, the reaction pressure is normal pressure, and the target product MMA is obtained after the reaction for 2h by filtration. The filtered reaction product was quantitatively analyzed by a SHIMADZU GC2010 type gas chromatograph.
The results are shown in Table 1.
Table 1 catalytic performance of the supported gold catalysts prepared in example 1 and comparative example 1
As can be seen from table 1: the addition of Na element improves the alkalescence of the catalyst, promotes the generation of intermediate product methoxy, and greatly improves the activity of the catalyst.
Comparative example 2
Adding 0.116g of Ni (NO 3)3·6H2 O) into water, stirring uniformly, adding a gamma alumina carrier, heating and stirring at 60 ℃ for 30min to enable the gamma alumina carrier to be fully dispersed, then adding a 0.5mol/L sodium carbonate aqueous solution, filtering to obtain a precipitate, placing the precipitate into a muffle furnace for vacuum drying for 12H at 55 ℃, placing the precipitate into the muffle furnace for roasting for 3H at 400 ℃, wherein the heating rate is 2 ℃/min during roasting, placing the precipitate into a tubular furnace, and reducing for 4H at 600 ℃ in an atmosphere of H 2 to obtain a Na-Ni catalyst, wherein the heating rate is 2 ℃/min during reduction;
adding 1.013mL of chloroauric acid solution with the concentration of 1g/50mL and 0.01g of protective agent (PVA) into water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, then adding Na-Ni catalyst, uniformly mixing the solution, standing for 6h, filtering to obtain a precipitate, washing and drying the precipitate for 10h, putting the precipitate into a muffle furnace, roasting the precipitate for 3h at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and roasting to obtain the Au-Na-NiOx catalyst;
The Au-Na-NiOx catalyst is subjected to roasting pretreatment to remove surface organic matters, then the Au-Na-NiOx catalyst is placed in a tube furnace and is roasted for 15min in the atmosphere of CH 4、H2 and Ar at the temperature of 850 ℃ to load carbon tubes on the surface of the Au-Na-NiOx catalyst, and the Au-Na-NiOx-C-15 min/gamma-Al 2O3 catalyst is obtained.
Comparative example 3
Adding 0.116g of Ni (NO 3)3·6H2 O) into water, stirring uniformly, adding a gamma alumina carrier, heating and stirring at 60 ℃ for 30min to enable the gamma alumina carrier to be fully dispersed, then adding a 0.5mol/L sodium carbonate aqueous solution, filtering to obtain a precipitate, placing the precipitate into a muffle furnace for vacuum drying for 12H at 55 ℃, placing the precipitate into the muffle furnace for roasting for 3H at 400 ℃, wherein the heating rate is 2 ℃/min during roasting, placing the precipitate into a tubular furnace, and reducing for 4H at 600 ℃ in an atmosphere of H 2 to obtain a Na-Ni catalyst, wherein the heating rate is 2 ℃/min during reduction;
adding 1.013mL of chloroauric acid solution with the concentration of 1g/50mL and 0.01g of protective agent (PVA) into water, carrying out ultrasonic treatment for 10min to uniformly disperse the solution, then adding Na-Ni catalyst, uniformly mixing the solution, standing for 6h, filtering to obtain a precipitate, washing and drying the precipitate for 10h, putting the precipitate into a muffle furnace, roasting the precipitate for 3h at the temperature of 300 ℃, wherein the heating rate is 2 ℃/min, and roasting to obtain the Au-Na-NiOx catalyst;
The Au-Na-NiOx catalyst is subjected to roasting pretreatment to remove surface organic matters, then the Au-Na-NiOx catalyst is placed in a tube furnace and is roasted for 60 minutes in the atmosphere of CH 4、H2 and Ar at the temperature of 850 ℃ to load carbon tubes on the surface of the Au-Na-NiOx catalyst, and the Au-Na-NiOx catalyst is recorded as Au-Na-NiOx-C-60 min/gamma-Al 2O3 catalyst.
Application example 3
40ML of CH 3 OH and 5mL of mLMAL are added into a three-necked flask, then 0.5g of the supported gold-based catalysts prepared in example 1 and comparative examples 2-3 are respectively placed into the three-necked flask, industrial oxygen is introduced for reaction, the reaction temperature is 60 ℃, the oxygen airspeed is 20mL/min, the reaction pressure is normal pressure, and the target product MMA is obtained after the reaction for 2 h. The filtered reaction product was quantitatively analyzed by a SHIMADZU GC2010 type gas chromatograph.
The results are shown in Table 2.
TABLE 2 catalytic Properties of Supported gold catalysts prepared in example 1 and comparative examples 2 to 3
As can be seen from table 2: too short a carbon component loading time may cause water generated by the reaction to affect the activity of the catalyst, while too long a carbon component loading time may cause carbon to cover active sites of Au, resulting in a decrease in the activity thereof.
Application example 4
Adding CH 3 OH and MAL into a three-necked flask, then respectively putting 1g of the Au-Na-NiO x-CNT/γ-Al2O3 catalyst prepared in the embodiment 1 into the three-necked flask, introducing industrial oxygen to perform reaction, wherein the reaction temperature is 60 ℃, the oxygen airspeed is 20mL/min, the reaction pressure is normal pressure, and filtering to obtain a target product MMA after reacting for 2 hours, wherein the volume ratio of CH 3 OH to MAL is 3:1, 5:1, 10:1 or 20:1 respectively; the filtered reaction product was quantitatively analyzed by a SHIMADZU GC2010 type gas chromatograph.
The results are shown in Table 3.
TABLE 3 catalytic Performance of the Supported gold catalysts prepared in example 1 under different aldol ratios
| Sample of | XMAL | SMMA |
| Alcohol aldehyde ratio 3 (volume ratio) | 92.7 | 96.8 |
| Alcohol aldehyde ratio 5 (volume ratio) | 98.71 | 98.2 |
| Alcohol to aldehyde ratio 10 (volume ratio) | 99.4 | 99.6 |
| Alcohol to aldehyde ratio 20 (volume ratio) | 99.1 | 99.8 |
As can be seen from table 3: the supported gold-based catalyst prepared in the embodiment 1 of the invention still shows high activity and high stability under the condition of low alcohol-aldehyde ratio, and lays a good foundation for industrialization.
Although the foregoing embodiments have been described in some, but not all embodiments of the invention, other embodiments may be obtained according to the present embodiments without departing from the scope of the invention.
Claims (9)
1. The supported gold-based catalyst is characterized by comprising a gamma alumina carrier, an active component and a carbon simple substance, wherein the active component and the carbon simple substance are supported on the gamma alumina carrier; the active component consists of a gold simple substance, an alkali metal oxide, a nickel simple substance and a nickel oxide thereof;
The molar ratio of aluminum element to alkali metal element in the supported gold-based catalyst is 1 (0.0016-0.0164);
The molar ratio of aluminum element to gold element in the supported gold-based catalyst is 1 (0.0018-0.0031);
The molar ratio of aluminum element to nickel element in the supported gold-based catalyst is 1 (0.0061-0.0130);
The molar ratio of aluminum element to carbon element in the supported gold-based catalyst is 1 (0.0425-0.0850);
The surface layer of the supported gold-based catalyst sequentially comprises a first layer structure, a second layer structure, a third layer structure and a fourth layer structure from outside to inside;
The first layer structure comprises aluminum element, gold element, carbon element, oxygen element and alkali metal element; the mass percentage of aluminum element in the first layer structure is 46.3-46.6%, the mass percentage of gold element in the first layer structure is 18.1-18.4%, the mass percentage of carbon element and oxygen element in the first layer structure is 29.4-29.7%, and the mass percentage of alkali metal element in the first layer structure is 5.6-5.9%;
the second layer structure comprises aluminum element, gold element, carbon element, oxygen element and alkali metal element; the mass percentage of aluminum element in the second layer structure is 46.9-47.2%, the mass percentage of gold element in the second layer structure is 17.5-17.8%, the mass percentage of carbon element and oxygen element in the second layer structure is 29.7-30.0%, and the mass percentage of alkali metal element in the second layer structure is 5.3-5.6%;
The third layer structure comprises aluminum element, gold element, carbon element, oxygen element, alkali metal element and nickel element; the mass percentage of aluminum element in the third layer structure is 44.4-45.8%, the mass percentage of gold element in the third layer structure is 19.8-20.8%, the mass percentage of carbon element and oxygen element in the third layer structure is 26.4-27.2%, and the mass percentage of alkali metal element in the third layer structure is 5.6-5.9%; the mass percentage of nickel element in the third layer structure is 1.3-2.9%;
The fourth layer structure comprises aluminum element, gold element, carbon element, oxygen element, alkali metal element and nickel element; the mass percentage of aluminum element in the fourth layer structure is 46.7-49.1%, the mass percentage of gold element in the fourth layer structure is 19.0-19.3%, the mass percentage of carbon element and oxygen element in the fourth layer structure is 24.9-25.2%, and the mass percentage of alkali metal element in the fourth layer structure is 5.2-7.2%; the mass percentage of nickel element in the fourth layer structure is 1.8-2.4%.
2. The supported gold-based catalyst according to claim 1, wherein the elemental nickel and its nickel oxide are present at 1.2nm or less on the surface of the supported gold-based catalyst.
3. The supported gold-based catalyst of claim 1, wherein the thickness of the first layer structure, the second layer structure, the third layer structure, and the fourth layer structure are each 0.6nm.
4. The supported gold-based catalyst of claim 1, wherein Jin Shanzhi is spherical gold nanoparticles having a particle size of 3-8 nm.
5. The supported gold-based catalyst of claim 1, wherein the elemental carbon comprises one or more of amorphous carbon, graphitic carbon, and carbon nanotubes.
6. The supported gold-based catalyst of claim 1, wherein the alkali metal oxide comprises sodium oxide and/or potassium oxide.
7. The method for preparing a supported gold-based catalyst as claimed in any one of claims 1 to 6, comprising the steps of:
mixing water-soluble nickel salt, water and gamma alumina carrier to obtain nickel salt dispersion system;
Mixing the nickel salt dispersion system with an alkali metal source, and carrying out solid-liquid separation to obtain a first solid precursor; the alkali metal source includes alkali metal hydroxide and alkali metal carbonate;
first roasting the first solid precursor to obtain a first roasting product;
Carrying out reduction reaction on the first roasting product in reducing gas to obtain a supported alkali metal oxide-nickel catalyst;
mixing the supported alkali metal oxide-nickel catalyst, a water-soluble gold source, an organic polymer and water, and standing for solid-liquid separation to obtain a second solid precursor;
Second roasting the second solid precursor to obtain a supported gold-alkali metal oxide-NiOx catalyst;
Thirdly roasting the supported gold-alkali metal oxide-NiOx catalyst in a reducing gas containing a carbon source to obtain the supported gold-based catalyst; the carbon source is a gaseous hydrocarbon.
8. The method of claim 7, wherein the first firing temperature is 400-450 ℃; the temperature of the reduction reaction is 600-650 ℃; the temperature of the second roasting is 300-350 ℃, and the temperature of the third roasting is 750-900 ℃.
9. The use of the supported gold-based catalyst according to any one of claims 1 to 6 or the supported gold-based catalyst prepared by the preparation method according to claim 7 or 8 in the preparation of carboxylic esters by oxidative esterification of aldehydes.
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