CN111672518A - Magnetic catalyst of monoatomic bimetal assembled by porous titanium oxide shell, preparation and application - Google Patents
Magnetic catalyst of monoatomic bimetal assembled by porous titanium oxide shell, preparation and application Download PDFInfo
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims abstract description 91
- 239000003054 catalyst Substances 0.000 title claims abstract description 74
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title claims abstract description 36
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 223
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims abstract description 147
- 239000010936 titanium Substances 0.000 claims abstract description 100
- 239000002077 nanosphere Substances 0.000 claims abstract description 68
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims abstract description 60
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- 229910052751 metal Inorganic materials 0.000 claims abstract description 26
- 239000002184 metal Substances 0.000 claims abstract description 26
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 6
- 238000010668 complexation reaction Methods 0.000 claims abstract description 4
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 153
- 239000000243 solution Substances 0.000 claims description 147
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 81
- 239000008367 deionised water Substances 0.000 claims description 73
- 229910021641 deionized water Inorganic materials 0.000 claims description 73
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 66
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 55
- 239000010931 gold Substances 0.000 claims description 52
- 229910052697 platinum Inorganic materials 0.000 claims description 50
- 238000003756 stirring Methods 0.000 claims description 47
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 44
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 43
- 239000007788 liquid Substances 0.000 claims description 38
- 229910052763 palladium Inorganic materials 0.000 claims description 35
- 230000001588 bifunctional effect Effects 0.000 claims description 33
- 238000005303 weighing Methods 0.000 claims description 33
- 229910052737 gold Inorganic materials 0.000 claims description 32
- 229910052709 silver Inorganic materials 0.000 claims description 32
- GPNNOCMCNFXRAO-UHFFFAOYSA-N 2-aminoterephthalic acid Chemical compound NC1=CC(C(O)=O)=CC=C1C(O)=O GPNNOCMCNFXRAO-UHFFFAOYSA-N 0.000 claims description 26
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 22
- 239000001632 sodium acetate Substances 0.000 claims description 22
- 235000017281 sodium acetate Nutrition 0.000 claims description 22
- 239000008187 granular material Substances 0.000 claims description 21
- 150000002500 ions Chemical class 0.000 claims description 21
- 238000006555 catalytic reaction Methods 0.000 claims description 20
- 229910002710 Au-Pd Inorganic materials 0.000 claims description 19
- 239000010944 silver (metal) Substances 0.000 claims description 18
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 claims description 18
- 230000003197 catalytic effect Effects 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 15
- 239000011259 mixed solution Substances 0.000 claims description 14
- 230000000536 complexating effect Effects 0.000 claims description 13
- 239000007791 liquid phase Substances 0.000 claims description 13
- 238000009210 therapy by ultrasound Methods 0.000 claims description 13
- 238000001291 vacuum drying Methods 0.000 claims description 13
- 238000005216 hydrothermal crystallization Methods 0.000 claims description 11
- 239000006185 dispersion Substances 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 6
- 101710134784 Agnoprotein Proteins 0.000 claims description 5
- 101150003085 Pdcl gene Proteins 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910021578 Iron(III) chloride Inorganic materials 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 2
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 claims description 2
- 239000004332 silver Substances 0.000 claims description 2
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 2
- 239000007858 starting material Substances 0.000 claims 1
- 239000000047 product Substances 0.000 description 16
- 239000000463 material Substances 0.000 description 12
- 239000010410 layer Substances 0.000 description 11
- 239000000725 suspension Substances 0.000 description 10
- 238000004587 chromatography analysis Methods 0.000 description 9
- 239000000843 powder Substances 0.000 description 9
- 238000007254 oxidation reaction Methods 0.000 description 7
- 238000009833 condensation Methods 0.000 description 5
- 230000005494 condensation Effects 0.000 description 5
- 230000032050 esterification Effects 0.000 description 5
- 238000005886 esterification reaction Methods 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 239000013206 MIL-53 Substances 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 239000003446 ligand Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 150000007524 organic acids Chemical class 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000005863 Friedel-Crafts acylation reaction Methods 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- ZGFPIGGZMWGPPW-UHFFFAOYSA-N formaldehyde;formic acid Chemical compound O=C.OC=O ZGFPIGGZMWGPPW-UHFFFAOYSA-N 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- 239000012621 metal-organic framework Substances 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000001338 self-assembly Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229920006221 acetate fiber Polymers 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 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
- 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
- B01J23/8906—Iron and noble metals
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- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/33—Electric or magnetic properties
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- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/396—Distribution of the active metal ingredient
- B01J35/398—Egg yolk like
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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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/51—Spheres
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
- B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
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- B01J37/088—Decomposition of a metal salt
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- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
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- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
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Abstract
A magnetic catalyst with monatomic bimetal assembled by a porous titanium oxide shell, a preparation method and an application belong to the technical field of catalysts. In the presence of magnetic Fe3O4The nuclear surface is synthesized with a layer with hanging-NH2NH of (2)2-MIL-125(Ti) shell, further reacting M metal ions with NH shell2pendant-NH in MIL-125(Ti)2Complexation to prepare M → NH2‑MIL‑125(Ti)@Fe3O4Nanosphere(ii) a Drying and roasting to make M → NH2MIL-125(Ti) decomposes into a porous titanium oxide shell, while the complexed metal M forms a monoatomic confinement in the porous titanium oxide shell. Has good methanol conversion rate and methyl formate selectivity, and the catalyst after reaction can be separated and recovered by an external magnetic field.
Description
Technical Field
The invention relates to a magnetic catalyst of monatomic bimetal assembled by a porous titanium oxide shell layer, preparation and a catalytic reaction for preparing methyl formate by one step with liquid-phase methanol, belonging to the technical field of monatomic metal magnetic catalysts and fine chemical engineering.
Background
Methanol is an important basic chemical raw material, and with the surplus of the methanol production capacity, the development of methanol downstream products with high added values has important significance. Among numerous downstream methanol products, methyl formate is a high value-added downstream methanol green chemical product which is in the spotlight of people. Methyl formate is an important organic synthesis intermediate, and is widely applied to the fields of acetate fiber synthesis, medicines, pesticides and the like.
In recent years, research shows that the supported catalyst with catalytic activity of Au, Pd and the like can catalytically convert liquid-phase methanol into methyl formate in one step. As found in Da Shi et al, Au-Pd/TiO was used2The bifunctional catalyst takes liquid-phase methanol as raw material, and can generate methyl formate (Da Shi, Jianfang Liu, Rui Sun, Shengfuji, Scott M.Rogers, Bethany M.Connolly, Nikolaos Dimitratos, Andrew E.H.Wheatley.preparation of biofunctional Au-Pd/TiO in one step under the condition of oxygen2catalysis today.2018,316, 206-213). Jianfang Liu et Al found that the liquid phase methanol can be catalytically converted into methyl formate in one step in the presence of oxygen by using a bifunctional catalyst in which MIL-53(Al) is used to assemble Pd active components (Jian-fang Liu, Jin-Cheng Mu, Rong-Xian Qin, Sheng-Fu. Pd nanoparticles immobilized on MIL-53(Al) as high purity effective binary catalysts for oxidation of methanol to methyl formate. Petroleum science 2019,16, 901-911). Compared with the traditional methyl formate production by methanol two-step method, the method has the advantages of simple process flow, less waste liquid, low production cost and the like, but the content of the noble metal catalytic active component is generally higher.
Recent studies have shown that the monatomic catalyst not only has a very low loading of metal active components, which greatly improves the utilization efficiency of metal Atoms, but also has a relatively stable monatomic catalytic active component loaded on a metal oxide support, such as Xiong Zhou, which is a highly dispersed Au monatomic catalyst prepared on a Single-layer CuO thin film support grown on the surface of a Cu (110) Single crystal, and has a very high stability in CO oxidation reactions (Xiong Zhou, Qian Shen, KaidiYuan, wenha Yang, Qiwei Chen, zhen, Jialin Zhang, Xiang o, Wei Chen, guoqiin Xu, Xueming Yang, Kai wu.
The metal organic framework material MIL-125(Ti) series is a porous crystal material generated by self-assembly of titanium metal ions and a polybasic organic acid ligand, and has the characteristics of a nanoscale framework type regular pore channel structure, large specific surface area, porosity and the like. If the titanium metal ion is reacted with a compound containing-NH2The polybasic organic acid ligand is self-assembled, and the suspension-NH can be generated2NH of (2)2-MIL-125(Ti) metal organic framework material, which suspends-NH2Can also be complexed with other metal ions through coordination at NH2-MIL-125(Ti) forming uniform metal-amino coordination complex metal ion nodes in the porous cavity, and when such NH having metal-amino coordination complex metal ion nodes2When MIL-125(Ti) is pyrolyzed in air, the organic acid ligand is decomposed to release gases such as carbon dioxide, water and the like; NH (NH)2Metal ions of MIL-125(Ti) may form ordered porous network oxides; and metal ion nodes of metal-amino coordination complex can form high-dispersion monoatomic metal.
With superparamagnetic Fe3O4The magnetic catalyst as the core can be easily separated and recovered by adopting an external magnetic field after the liquid phase catalytic reaction is finished. We use superparamagnetic Fe3O4MIL-53(Al) @ SiO prepared as nucleus2@Fe3O4The magnetic catalyst can be easily recovered and reused by adopting an external magnetic field in the Friedel-Crafts acylation reaction process, and still has good performance after being repeatedly recycled for 5 times (Sai Jiang, Junlei Yan, Fabien Habimana, Shengfu Jible MIL-53(Al)@SiO2@Fe3O4catalysts and their catalytic performance for Friedel-Crafts acylationreaction.Catalysis Today,2016,264,83-90)。
Based on these research works, the idea of the present invention is to first prepare Fe having superparamagnetism3O4A core; then in the presence of magnetic Fe3O4The nuclear surface is synthesized with a layer with hanging-NH2NH of (2)2-MIL-125(Ti) shell to prepare magnetic NH2-MIL-125(Ti)@Fe3O4Nanospheres. Due to NH2MIL-125(Ti) is a porous crystalline material formed by self-assembly of titanium metal ions and 2-aminoterephthalic acid, containing dangling-NH2Can be coordinated and complexed with metal ions such as Au, Pd, Pt, Ag and the like in NH2Uniform Au-amino coordination, Pd-amino coordination, Pt-amino coordination, Ag-amino coordination and other nodes are formed in the porous cavity of the-MIL-125 (Ti), and then magnetic Au (Pd, Pt, Ag) → NH is prepared2-MIL-125(Ti)@Fe3O4Nanospheres. Then roasting in air atmosphere to make NH2Decomposing MIL-125(Ti) into a porous titanium oxide shell, and confining nodes such as Au-amino coordination, Pd-amino coordination, Pt-amino coordination, Ag-amino coordination and the like in the porous titanium oxide shell to form high-dispersion monatomic Au, Pd, Pt and Ag, so as to prepare magnetic Au (Pd, Pt, Ag) → TiO methyl formate prepared by liquid-phase methanol catalytic conversion of monatomic Au, Pd, Pt and Ag assembled by the porous titanium oxide shell2@Fe3O4Catalyst, and monatomic bimetallic Au-Pd (Au-Pt, Au-Ag) → TiO consisting of monatomic Au and monatomic Pd, Pt and Ag2@Fe3O4The magnetic catalyst has better catalytic performance.
In the invention, NH is adopted2pendant-NH in MIL-125(Ti)2Preparing Au (Pd, Pt, Ag) → NH by complexing with Au, Pd, Pt, Ag and other ions2MIL-125(Ti), so Au (Pd, Pt, Ag) → NH during firing2Decomposition of MIL-125(Ti) into an ordered porous titanium oxide shell with simultaneous confinement of the complexed Au, Pd, Pt, Ag to form a monoatomic species in the porous titanium oxide shellThe bimetal Au-Pd, Au-Pt and Au-Ag has very good methanol selective oxidation performance, and meanwhile, the rich acid center of the porous titanium oxide has good catalytic condensation (or esterification) performance. Therefore, the magnetic Au-Pd (Au-Pt, Au-Ag) → TiO prepared by the invention2@Fe3O4The catalyst has good catalytic action on the methanol liquid phase selective oxidation to generate formaldehyde (formic acid) and the further condensation (esterification) of the formaldehyde (formic acid) and the methanol generated in the reaction process, and is a bifunctional catalyst for synthesizing methyl formate by one step of methanol, which can couple the catalytic selective oxidation reaction and the catalytic condensation (or esterification) reaction.
The novel magnetic Au-Pd (Au-Pt, Au-Ag) → TiO prepared by the method2@Fe3O4The bifunctional catalyst not only has good catalytic reaction performance for converting liquid-phase methanol into methyl formate in one step, but also can be easily separated from reactants by using an external magnetic field after reaction, and the operations of recovering and recycling the catalyst and the like are also simpler, so that the bifunctional catalyst has important industrial application value.
Disclosure of Invention
The invention aims to provide a bifunctional catalyst for converting methanol into methyl formate in one step through catalysis, and a preparation method and application thereof.
The invention firstly prepares the Fe with superparamagnetism3O4A core; then in the presence of magnetic Fe3O4The nuclear surface is synthesized with a layer with hanging-NH2NH of (2)2-MIL-125(Ti) shell, preparation of NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres; further, M (selected from Au, Pd, Pt, Ag, etc.) metal ions and shell NH2pendant-NH in MIL-125(Ti)2Complexation to prepare M → NH2-MIL-125(Ti)@Fe3O4Nanospheres; drying and roasting to make M → NH2-MIL-125(Ti) is decomposed into a porous titanium oxide shell, and meanwhile, a monoatomic metal M formed by complexing is confined in the porous titanium oxide shell, so that the methyl formate prepared by the liquid-phase catalytic conversion of methanol with the monoatomic bimetallic M such as Au-Pd, Au-Pt and Au-Ag assembled on the porous titanium oxide shell is preparedMagnetic M → TiO2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4A catalyst.
More preferably, the magnetic material of the present invention is Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The preparation of the bifunctional catalyst specifically comprises the following steps:
(1) magnetic Fe3O4Preparing particles:
preferably: FeCl is added3·6H2Dissolving O in deionized water to prepare FeCl310-15% of solution. Dissolving sodium acetate in ethylene glycol to prepare ethylene glycol solution with the mass content of the sodium acetate of 5-10%. At 30 ℃ with N2Under the protection and stirring conditions, FeCl is added3The solution was added dropwise to a glycol solution of sodium acetate in which FeCl was present3And sodium acetate in a mass ratio of 3: 1, after the dropwise addition, putting the mixed solution into a high-pressure kettle, crystallizing at 180 ℃ for 8 hours, naturally cooling, washing with deionized water and ethanol respectively, and drying at 60 ℃ in vacuum to obtain the prepared magnetic Fe3O4Particles;
(2) magnetic NH2-MIL-125(Ti)@Fe3O4Preparing nanospheres: weighing a certain amount of prepared magnetic Fe3O4Adding the granules into ethanol to prepare Fe3O4Solution of (1), denoted as solution A, Fe3O4The mass concentration of the active carbon is 5 to 10 percent; weighing a certain amount of isopropyl titanate (TPOT) and dissolving the isopropyl titanate (TPOT) in dimethyl formamide (DMF) to prepare a solution of isopropyl titanate, wherein the mass concentration of the isopropyl titanate is 5-10 percent; weighing a certain amount of 2-amino terephthalic acid (NH)2-H2BDC) is dissolved in Dimethylformamide (DMF) to prepare a solution of 2-amino terephthalic acid, which is marked as solution C, wherein the mass concentration of the 2-amino terephthalic acid is 5 to 10 percent; adding the B solution and the C solution into the A solution simultaneously under the stirring condition of 30-60 ℃, wherein the dropwise adding amount is Fe3O4: isopropyl titanate: the mass ratio of the 2-amino terephthalic acid is 1: (0.3-0.8): (0.2-0.6), fully stirring, and then carrying out ultrasonic treatment for 30 min-50 mi under the ultrasonic power of 160W-200Wn, then placing the mixed solution into a high-pressure kettle, carrying out hydrothermal crystallization for 68-72 hours at the temperature of 130-150 ℃, naturally cooling, respectively washing with DMF and methanol, and then carrying out vacuum drying for 12 hours at the temperature of 60 ℃ to obtain the prepared magnetic NH2-MIL-125(Ti)@Fe3O4Nanospheres;
(3) magnetic M → NH2-MIL-125(Ti)@Fe3O4Preparing nanospheres: weighing a certain amount of magnetic NH2-MIL-125(Ti)@Fe3O4Dispersing the nanospheres in deionized water to prepare NH2-MIL-125(Ti)@Fe3O4Dispersion, NH2-MIL-125(Ti)@Fe3O4The mass concentration is 20-30%; weighing a certain amount of metal M salt, and dissolving the metal M salt in deionized water to prepare a solution, wherein the mass percentage concentration of the metal M is preferably 0.1-0.5%; respectively dripping the metal M salt solution into the magnetic NH under stirring2-MIL-125(Ti)@Fe3O4Fully stirring the nano-sphere dispersion liquid, and then carrying out ultrasonic treatment for 30-50 min under the ultrasonic power of 60-100W to finish the metal M ions and the shell NH2pendant-NH in MIL-125(Ti)2The complex is then washed with deionized water and ethanol, respectively, and vacuum dried, e.g., at 50 deg.C for 8 hours, to obtain the magnetic M → NH2-MIL-125(Ti)@Fe3O4Nanospheres.
Weighing a certain amount of M metal salt, dissolving in deionized water to prepare a solution containing one or more of the following components: weighing a certain amount of chloroauric acid (HAuCl)4) Dissolving in deionized water to prepare a solution with the gold mass concentration of 0.1-0.5%; weighing a certain amount of palladium chloride (PdCl)2) Dissolving the palladium in deionized water to prepare a palladium solution with the mass concentration of 0.1-0.5 percent; weighing a certain amount of chloroplatinic acid (H)2PtCl6·6H2O) is dissolved in deionized water to prepare a solution with platinum mass concentration of 0.1-0.5%; weighing a certain amount of silver nitrate (AgNO)3) Dissolving in deionized water to prepare a solution with the silver mass concentration of 0.1-0.5%.
(4) Magnetic M → TiO2@Fe3O4Preparing a catalyst: weighing a certain amountMagnetic M → NH of2-MIL-125(Ti)@Fe3O4Placing the nanospheres into a tubular reactor, roasting at room temperature to (320-380 ℃) under the air atmosphere with a certain flow rate at a programmed temperature, and keeping roasting at 320-380 ℃ for 4-6 hours to obtain the prepared magnetic M → TiO2@Fe3O4A catalyst.
Wherein, the metal M element is selected from at least one, preferably two, more preferably any one of Au and other three of Au, Pd, Pt and Ag, and the mass content of each metal can reach 0.1wt percent to 0.5wt percent respectively.
The invention adopts the prepared magnetic M → TiO2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The catalyst dual-function catalyst is applied to methanol liquid phase selective oxidation coupling catalytic condensation (esterification) reaction, and methyl formate is synthesized by methanol in one step; the catalytic reaction is carried out in a kettle type stirring reactor, liquid methanol is taken as a raw material, and magnetic M → TiO is added2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The bifunctional catalyst is added with H with the molar equivalent to that of methanol2O2Carrying out catalytic reaction at 70-80 deg.c to obtain methyl formate product. The results show that the magnetic material prepared M → TiO2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The bifunctional catalyst has good methanol conversion rate and methyl formate selectivity, and the reacted catalyst can be separated and recovered by an external magnetic field, so that the bifunctional catalyst has good recycling performance.
Magnetic M → TiO prepared by the invention2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The bifunctional catalyst has the following remarkable advantages:
(1) in magnetic NH2-MIL-125(Ti)@Fe3O4Shell NH of nanosphere2Suspension of MIL-125(Ti) -NH2In the process of coordination and complexation with ions such as Au, Pd, Pt and Ag, the ultrasonic method is adopted to ensure that Au is subjected to complexationPd, Pt, Ag plasma and suspension-NH2The complexing process of (A) is both fast, coordinative and stable, and thus Au (Pd, Pt, Ag) → NH2When the-MIL-125 (Ti) is decomposed into porous titanium oxide, the formation of highly dispersed monoatomic bimetallic Au-Pd, Au-Pt, Au-Ag and other catalytic active sites provides guarantee.
(2) Magnetic M → TiO preparation2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4In the bifunctional catalyst, the catalytic active component is a high-dispersion monatomic bimetallic M such as Au-Pd, Au-Pt and Au-Ag assembled in a porous titanium oxide shell layer, so that the aggregation and loss of the catalytic active component in the reaction process can be avoided, the stability of the catalyst is greatly improved, the contents of the catalytic active components such as Au, Pd, Pt and Ag are extremely low, and the utilization efficiency of noble metals such as Au, Pd, Pt and Ag is greatly improved.
(3) Magnetic Au-Pd (Au-Pt, Au-Ag) → TiO prepared2@Fe3O4The bifunctional catalyst can couple selective oxidation, condensation and esterification of methanol together, so that the methanol is catalytically converted into methyl formate in one step, and the bifunctional catalyst has good conversion rate and selectivity, can be separated, recovered and recycled by an external magnetic field after reaction, and reduces the separation cost of liquid phase catalytic reaction, thereby having important industrial application value.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited thereto.
Example 1
(1) 17.6g of FeCl were weighed3·6H2O was dissolved in 82.4g deionized water to make a solution (FeCl)3Concentration 10.5%), 3.5g of sodium acetate was dissolved in 46.5g of ethylene glycol to prepare a solution (concentration 7.0%), and the solution was added dropwise to a solution of N while stirring at a bath temperature of 30 ℃2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.5g of granules are added into 91.5g of ethanol to prepare solution A (the concentration is 8.5 percent); 3.4g of isopropyl titanate (TPOT) is weighed and dissolved in 46.6g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 6.8%); 3.2g of 2-aminoterephthalic acid was dissolved in 46.8g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 6.4%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 50min under the ultrasonic power of 160W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 72 hours at 130 ℃, naturally cooling, respectively washing 3 times with DMF and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the product marked as 3.8NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.34g of HAuCl was weighed out4Dissolving in 99.66g of deionized water to prepare a 0.20 wt% Au solution; 0.53g of PdCl are weighed out2Dissolving in 99.47g deionized water to prepare a solution of 0.32 wt% Pd; 12.3g of the resulting 3.8NH were weighed2-MIL-125(Ti)@Fe3O4Adding nanosphere into 50.0g deionized water, adding 10.0g of 0.20 wt% Au solution, adding 10.0g of 0.32 wt% Pd solution, stirring, and ultrasonic treating at 60W ultrasonic power for 45min to obtain shell NH2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pd ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material which is marked as 0.20Au-0.32Pd → 3.8NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.20Au-0.32Pd → 3.8NH was weighed2-MIL-125(Ti)@Fe3O4The magnetic nanospheres are put into a tubular reactor, heated to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, kept roasted for 5 hours at 350 ℃, and naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.20 wt% Au-0.32 wt% Pd → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a kettle typeIn a stirred reactor, methanol was added first, followed by 0.20 wt% Au-0.32 wt% Pd → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction was carried out at 75 ℃. After completion of the reaction, the conversion to methanol was 60.6% and the selectivity to methyl formate was 92.3%, as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 2
(1) 17.6g of FeCl were weighed3·6H2O was dissolved in 82.4g deionized water to make a solution (FeCl)3Concentration 10.5%), 3.5g of sodium acetate was dissolved in 46.5g of ethylene glycol to prepare a solution (concentration 7.0%), and the solution was added dropwise to a solution of N while stirring at a bath temperature of 30 ℃2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.3g of granules are added into 91.7g of ethanol to prepare solution A (the concentration is 8.3 percent); 3.7g of isopropyl titanate (TPOT) is weighed and dissolved in 46.3g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 7.4%); 3.6g of 2-aminoterephthalic acid was dissolved in 46.4g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 7.2%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 40min under the ultrasonic power of 180W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 70 hours at 140 ℃, naturally cooling, respectively washing 3 times with DMF (dimethyl formamide) and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.2NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.68g of HAuCl was weighed out4Dissolving in 99.32g deionized water to prepare a 0.39 wt% Au solution; 0.35g of PdCl are weighed out2Dissolved in 99.65g of deionized waterTo prepare a solution of 0.21 wt% Pd; 12.5g of the 4.2NH thus obtained are weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.39 wt% Au solution, adding 10.0g of 0.21 wt% Pd solution, stirring, and ultrasonic treating at 70W ultrasonic power for 45min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pd ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material which is recorded as 0.39Au-0.21Pd → 4.2NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of the prepared 0.39Au-0.21Pd → 4.2NH was weighed2-MIL-125(Ti)@Fe3O4The magnetic nanospheres are put into a tubular reactor, heated to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, kept roasted for 4 hours at 350 ℃, and naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.39 wt% Au-0.21 wt% Pd → TiO → the2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.39 wt% Au-0.21 wt% Pd → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 80 ℃. After completion of the reaction, the conversion to methanol was 62.2% and the selectivity to methyl formate was 93.6% as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 3
(1) 21.6g of FeCl were weighed3·6H2O was dissolved in 78.4g deionized water to make a solution (FeCl)312.9 percent of sodium acetate, 4.3g of sodium acetate is weighed and dissolved in 45.7g of ethylene glycol to prepare a solution (the concentration is 8.6 percent), and the solution is added dropwise into a solution containing N at the same time under the conditions of water bath temperature of 30 ℃ and stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively at 60 DEG CVacuum drying for 8 hours to obtain the magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.3g of granules are added into 91.7g of ethanol to prepare solution A (the concentration is 8.3 percent); 3.9g of isopropyl titanate (TPOT) is weighed and dissolved in 46.1g of Dimethylformamide (DMF) to prepare a solution B (TPOT concentration is 7.8%); 3.7g of 2-aminoterephthalic acid was dissolved in 46.3g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 7.4%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 30min under the ultrasonic power of 200W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 68 hours at 150 ℃, naturally cooling, respectively washing for 3 times by using DMF (dimethyl formamide) and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.4NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.82g of HAuCl was weighed out4Dissolving in 99.18g deionized water to obtain 0.47 wt% Au solution; 0.18g of PdCl are weighed out2Dissolving in 99.82g deionized water to prepare a solution of 0.11 wt% Pd; 12.7g of the 4.4NH thus obtained were weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.47 wt% Au solution, adding 10.0g of 0.11 wt% Pd solution, stirring, and ultrasonic treating at 80W ultrasonic power for 40min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pd ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material designated as 0.47Au-0.11Pd → 4.4NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.47Au-0.11Pd → 4.4NH was weighed2-MIL-125(Ti)@Fe3O4The magnetic nanospheres are put into a tubular reactor, heated to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, kept roasted for 4 hours at 350 ℃, and naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.47 wt% Au-0.11 wt% Pd → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.47 wt% Au-0.11 wt% Pd → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 70 ℃. After completion of the reaction, the conversion to methanol was 60.1% and the selectivity to methyl formate was 94.2%, as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 4
(1) 21.6g of FeCl were weighed3·6H2O was dissolved in 78.4g deionized water to make a solution (FeCl)312.9 percent of sodium acetate, 4.3g of sodium acetate is weighed and dissolved in 45.7g of ethylene glycol to prepare a solution (the concentration is 8.6 percent), and the solution is added dropwise into a solution containing N at the same time under the conditions of water bath temperature of 30 ℃ and stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.2g of granules are added into 91.8g of ethanol to prepare solution A (the concentration is 8.2 percent); weighing 4.1g of isopropyl titanate (TPOT) and dissolving in 45.9g of Dimethylformamide (DMF) to prepare a solution B (TPOT concentration is 8.2%); 3.9g of 2-aminoterephthalic acid was dissolved in 46.1g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 7.8%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 40min under the ultrasonic power of 170W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 70 hours at 140 ℃, naturally cooling, respectively washing 3 times with DMF (dimethyl formamide) and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.6NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.32g of HAuCl was weighed out4Dissolving in 99.68g deionized water to make 0.18 wt%A solution of Au; 1.13g of H are weighed2PtCl6·6H2Dissolving O in 98.87g of deionized water to prepare a 0.42 wt% Pt solution; 12.8g of the 4.6NH thus obtained are weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.18 wt% Au solution, adding 10.0g of 0.42 wt% Pt solution, stirring, and ultrasonic treating at 100W ultrasonic power for 30min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pt ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material designated as 0.18Au-0.42Pt → 4.6NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.18Au-0.42Pt → 4.6NH was weighed out2-MIL-125(Ti)@Fe3O4The magnetic nanospheres are put into a tubular reactor, heated to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, kept roasted for 5 hours at 350 ℃, and naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.18 wt% Au-0.42 wt% Pt → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.18 wt% Au-0.42 wt% Pt → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction was carried out at 75 ℃. After completion of the reaction, the conversion to methanol was 61.8% and the selectivity to methyl formate was 93.5%, as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 5
(1) 24.3g of FeCl were weighed3·6H2Dissolving O in 75.7g deionized water to prepare FeCl solution314.6%) of sodium acetate, 4.9g of sodium acetate was dissolved in 45.1g of ethylene glycol to prepare a solution (concentration: 9.8%), and the solution was added dropwise to a solution of N in water at 30 ℃ while stirring2In a protected reactor, after the dropwise addition is finished, the mixed solution is put into an autoclaveCrystallizing at 180 deg.C for 8 hr, naturally cooling, washing with deionized water and ethanol for three times, and vacuum drying at 60 deg.C for 8 hr to obtain the magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.0g of granules are added into 92.0g of ethanol to prepare solution A (the concentration is 8.0 percent); weighing 4.4g of isopropyl titanate (TPOT) and dissolving in 45.6g of Dimethylformamide (DMF) to prepare a solution B (the concentration of TPOT is 8.8%); 4.2g of 2-aminoterephthalic acid was dissolved in 45.8g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 8.4%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 30min under the ultrasonic power of 190W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 72 hours at 135 ℃, naturally cooling, respectively washing 3 times with DMF and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.9NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.61g of HAuCl was weighed out4Dissolving in 99.39g of deionized water to prepare a 0.35 wt% Au solution; 0.62g of H is weighed out2PtCl6·6H2Dissolving O in 99.38g of deionized water to prepare a 0.23 wt% Pt solution; 12.9g of the 4.9NH thus obtained were weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.35 wt% Au solution, adding 10.0g of 0.23 wt% Pt solution, stirring, and ultrasonic treating at 90W ultrasonic power for 35min to obtain NH in shell layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pt ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material designated as 0.35Au-0.23Pt → 4.9NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.35Au-0.23Pt → 4.9NH was weighed out2-MIL-125(Ti)@Fe3O4Magnetic nanospheres are placed in a tubular reactor, heated to 350 ℃ with a 1 ℃/min program at an air flow of 1ml/min and kept calcined at 350 ℃Naturally cooling to room temperature after 6 hours to obtain the prepared product which is marked as 0.35 wt% Au-0.23 wt% Pt → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.35 wt% Au-0.23 wt% Pt → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 80 ℃. After completion of the reaction, the conversion to methanol was 63.7% and the selectivity to methyl formate was 93.1% as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 6
(1) 24.3g of FeCl were weighed3·6H2O was dissolved in 75.7g deionized water to make a solution (FeCl)314.6%) of sodium acetate, 4.9g of sodium acetate was dissolved in 45.1g of ethylene glycol to prepare a solution (concentration: 9.8%), and the solution was added dropwise to a solution of N in water at 30 ℃ while stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.4g of granules are added into 91.6g of ethanol to prepare solution A (the concentration is 8.4 percent); 3.5g of isopropyl titanate (TPOT) is weighed and dissolved in 46.5g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 7.0%); 3.4g of 2-aminoterephthalic acid was dissolved in 46.6g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 6.8%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 45min under the ultrasonic power of 180W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 68 hours at 130 ℃, naturally cooling, respectively washing for 3 times by using DMF (dimethyl formamide) and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.0NH2-MIL-125(Ti)@Fe3O4Magnetic nanoRice ball.
(3) 0.71g of HAuCl was weighed out4Dissolving in 99.29g deionized water to obtain 0.41 wt% Au solution; 0.46g of H is weighed out2PtCl6·6H2Dissolving O in 99.54g of deionized water to prepare a 0.17 wt% Pt solution; 12.4g of the 4.0NH thus obtained are weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.41 wt% Au solution, adding 10.0g of 0.17 wt% Pt solution, stirring, and ultrasonic treating at 80W ultrasonic power for 50min to obtain shell NH2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Pt ions. Then washed with deionized water and ethanol, filtered, and dried under vacuum at 50 ℃ for 8 hours to obtain a powder material designated as 0.41Au-0.17Pt → 4.0NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.41Au-0.17Pt → 4.0NH was weighed2-MIL-125(Ti)@Fe3O4The magnetic nanospheres are put into a tubular reactor, heated to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, kept at 350 ℃ for roasting for 5 hours, and naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.41 wt% Au-0.17 wt% Pt → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.41 wt% Au-0.17 wt% Pt → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 70 ℃. After completion of the reaction, the conversion to methanol was 62.5% and the selectivity to methyl formate was 92.8%, as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 7
(1) 17.6g of FeCl were weighed3·6H2O was dissolved in 82.4g deionized water to make a solution (FeCl)3Concentration 10.5%), 3.5g of sodium acetate was weighed out and dissolved in 46.5g of ethylene glycol to prepare a solution (concentration 7.0%), and the solution was heated in a water bath at 30 ℃Simultaneously dropwise adding N under stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.3g of granules are added into 91.7g of ethanol to prepare solution A (the concentration is 8.3 percent); 3.8g of isopropyl titanate (TPOT) is weighed and dissolved in 46.2g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 7.6%); 3.7g of 2-aminoterephthalic acid was dissolved in 46.3g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 7.4%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 50min under the ultrasonic power of 160W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 70 hours at 135 ℃, naturally cooling, respectively washing 3 times with DMF and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.3NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.38g of HAuCl was weighed out4Dissolving in 99.62g deionized water to obtain 0.22 wt% Au solution; 0.51g of AgNO was weighed3Dissolving in 99.49g deionized water to prepare a solution of 0.32 wt% Ag; 12.6g of the 4.3NH thus obtained were weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.22 wt% Au solution, adding 10.0g of 0.32 wt% Ag solution, stirring, and ultrasonic treating at 70W ultrasonic power for 50min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Ag ions. Then washing with deionized water and ethanol, filtering, vacuum drying at 50 deg.C for 8 hr to obtain powder material (0.22 Au-0.32Ag → 4.3 NH)2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.22Au-0.32Ag → 4.3NH was weighed2-MIL-125(Ti)@Fe3O4Magnetic nanospheres are put into a tubular reactor,heating to 350 deg.C with 1 deg.C/min air flow of 1ml/min, roasting at 350 deg.C for 4 hr, and naturally cooling to room temperature to obtain the final product, i.e. 0.22 wt% Au-0.32 wt% Ag → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.22 wt% Au-0.32 wt% Ag → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 80 ℃. After completion of the reaction, the conversion to methanol was 62.9% and the selectivity to methyl formate was 93.1% as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 8
(1) 21.6g of FeCl were weighed3·6H2O was dissolved in 78.4g deionized water to make a solution (FeCl)312.9 percent of sodium acetate, 4.3g of sodium acetate is weighed and dissolved in 45.7g of ethylene glycol to prepare a solution (the concentration is 8.6 percent), and the solution is added dropwise into a solution containing N at the same time under the conditions of water bath temperature of 30 ℃ and stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.2g of granules are added into 91.8g of ethanol to prepare solution A (the concentration is 8.2 percent); 4.0g of isopropyl titanate (TPOT) is weighed out and dissolved in 46.0g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 8.0%); 3.9g of 2-aminoterephthalic acid was dissolved in 46.1g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 7.8%). Adding the solution B and the solution C into the solution A simultaneously under stirring at 40 deg.C, stirring thoroughly after the dropwise addition, performing ultrasonic treatment at 200W for 30min, placing the mixed solution into an autoclave, performing hydrothermal crystallization at 145 deg.C for 68 hr, cooling naturally, washing with DMF and methanol for 3 times, respectively, and vacuum drying at 60 deg.C12 hours, the prepared product is marked as 4.5NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.58g of HAuCl was weighed out4Dissolving in 99.42g deionized water to prepare a 0.33 wt% Au solution; 0.40g of AgNO was weighed3Dissolving in 99.60g deionized water to prepare a solution of 0.25 wt% Ag; 12.7g of the 4.5NH thus obtained were weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.33 wt% Au solution, adding 10.0g of 0.25 wt% Ag solution, stirring, and ultrasonic treating at 90W ultrasonic power for 35min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Ag ions. Then washed with deionized water and ethanol, filtered, and vacuum dried at 50 deg.C for 8 hours to obtain a powder material designated as 0.33Au-0.25Ag → 4.5NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.33Au-0.25Ag → 4.5NH was weighed2-MIL-125(Ti)@Fe3O4Magnetic nanospheres are placed into a tubular reactor, the temperature is raised to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, the magnetic nanospheres are roasted for 6 hours at 350 ℃, and the magnetic nanospheres are naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.33 wt% Au-0.25 wt% Ag → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.33 wt% Au-0.25 wt% Ag → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction was carried out at 75 ℃. After completion of the reaction, the conversion to methanol was 61.7% and the selectivity to methyl formate was 93.3%, as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Example 9
(1) 24.3g of FeCl were weighed3·6H2O was dissolved in 75.7g deionized water to make a solution (FeCl)3Concentration 14.6%), 4.9g of sodium acetate were weighed out and dissolved in 45%1g of ethylene glycol to prepare a solution (the concentration is 9.8 percent), and the solution is simultaneously added dropwise to the solution containing N under the conditions of water bath temperature of 30 ℃ and stirring2After the dropwise addition is finished in a protected reactor, the mixed solution is put into a high-pressure kettle, crystallized for 8 hours at 180 ℃, naturally cooled, washed for three times by deionized water and ethanol respectively, and dried for 8 hours in vacuum at 60 ℃ to obtain the prepared magnetic Fe3O4And (3) granules.
(2) Weighing the prepared magnetic Fe3O48.1g of granules are added into 91.9g of ethanol to prepare solution A (the concentration is 8.1 percent); weighing 4.3g of isopropyl titanate (TPOT) and dissolving in 45.7g of Dimethylformamide (DMF) to prepare solution B (TPOT concentration is 8.6%); 4.1g of 2-aminoterephthalic acid was dissolved in 45.9g of Dimethylformamide (DMF) to prepare solution C (NH)2-H2BDC concentration 8.2%). Under the condition of stirring at 40 ℃, simultaneously adding the liquid B and the liquid C into the liquid A, fully stirring after the dropwise adding is finished, then carrying out ultrasonic treatment for 50min under the ultrasonic power of 170W, then putting the mixed liquid into an autoclave, carrying out hydrothermal crystallization for 70 hours at 150 ℃, naturally cooling, respectively washing 3 times with DMF (dimethyl formamide) and methanol, and then carrying out vacuum drying for 12 hours at 60 ℃, thus obtaining the prepared solution marked as 4.8NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(3) 0.65g of HAuCl was weighed out4Dissolving in 99.35g deionized water to prepare 0.37 wt% Au solution; 0.31g of AgNO was weighed3Dissolving in 99.69g deionized water to obtain 0.19 wt% Ag solution; 12.9g of the 4.8NH thus obtained were weighed out2-MIL-125(Ti)@Fe3O4Adding magnetic nanosphere into 50.0g deionized water, adding 10.0g of 0.37 wt% Au solution, adding 10.0g of 0.25 wt% Ag solution, stirring, and ultrasonic treating at 100W ultrasonic power for 30min to obtain NH layer2Suspension of MIL-125(Ti) -NH2Fully coordinating and complexing with Au ions and Ag ions. Then washed with deionized water and ethanol, filtered, and vacuum dried at 50 deg.C for 8 hours to obtain a powder material designated as 0.33Au-0.25Ag → 4.8NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres.
(4) 5.0g of prepared 0.33Au-0.25Ag → 4.8NH was weighed2-MIL-125(Ti)@Fe3O4Magnetic nanospheres are placed into a tubular reactor, the temperature is raised to 350 ℃ by the program of 1 ℃/min under the air flow of 1ml/min, the magnetic nanospheres are roasted for 5 hours at 350 ℃, and the magnetic nanospheres are naturally cooled to the room temperature, namely the prepared magnetic nanospheres are marked as 0.33 wt% Au-0.25 wt% Ag → TiO2@Fe3O4A magnetic bifunctional catalyst.
In a stirred tank reactor, methanol was added first, followed by 0.33 wt% Au-0.25 wt% Ag → TiO2@Fe3O4Magnetic bifunctional catalyst, then adding H with equal mole of methanol2O2The catalytic reaction is carried out at 80 ℃. After completion of the reaction, the conversion to methanol was 63.3% and the selectivity to methyl formate was 94.1% as determined by chromatography. The catalyst is repeatedly recycled for 5 times, and the conversion rate of methanol and the selectivity of products are not obviously reduced.
Claims (10)
1. A preparation method of a magnetic catalyst of monoatomic bimetal assembled by a porous titanium oxide shell is characterized by comprising the following steps: in the presence of magnetic Fe3O4The nuclear surface is synthesized with a layer with hanging-NH2NH of (2)2-MIL-125(Ti) shell, preparation of NH2-MIL-125(Ti)@Fe3O4Magnetic nanospheres; further the M metal ion and the shell NH2pendant-NH in MIL-125(Ti)2Complexation to prepare M → NH2-MIL-125(Ti)@Fe3O4Nanospheres; drying and roasting to make M → NH2Decomposing MIL-125(Ti) into porous titanium oxide shell, and simultaneously forming monoatomic metal M by complexing and confining in the porous titanium oxide shell to prepare magnetic M → TiO of methyl formate by using the porous titanium oxide shell to assemble monoatomic bimetallic M such as Au-Pd, Au-Pt and Au-Ag through methanol liquid phase catalytic conversion2@Fe3O4And M is at least one selected from Au, Pd, Pt and Ag, and when two are selected, the M is bimetal.
2. The method for preparing a magnetic catalyst of a porous titanium oxide shell assembled with a monatomic bimetal according to claim 1, comprising the steps of:
(1) magnetic Fe3O4Preparing particles;
(2) magnetic NH2-MIL-125(Ti)@Fe3O4Preparing nanospheres: weighing a certain amount of prepared magnetic Fe3O4Adding the granules into ethanol to prepare Fe3O4The solution of (1) is marked as solution A; weighing a certain amount of isopropyl titanate (TPOT) and dissolving in dimethyl formamide (DMF) to prepare a solution of isopropyl titanate, and marking as solution B; weighing a certain amount of 2-amino terephthalic acid (NH)2-H2BDC) is dissolved in Dimethylformamide (DMF) to prepare a solution of 2-amino terephthalic acid, which is marked as solution C; adding the B solution and the C solution into the A solution simultaneously under the stirring condition of 30-60 ℃, wherein the dropwise adding amount is Fe3O4: isopropyl titanate: the mass ratio of the 2-amino terephthalic acid is 1: (0.3-0.8): (0.2-0.6), fully stirring, performing ultrasonic treatment for 30-50 min under the ultrasonic power of 160-200W, then putting the mixed solution into an autoclave, performing hydrothermal crystallization for 68-72 hours at the temperature of 130-150 ℃, naturally cooling, washing with DMF (dimethyl formamide) and methanol respectively, and then performing vacuum drying to obtain the prepared magnetic NH2-MIL-125(Ti)@Fe3O4Nanospheres;
(3) magnetic M → NH2-MIL-125(Ti)@Fe3O4Preparing nanospheres: weighing a certain amount of magnetic NH2-MIL-125(Ti)@Fe3O4Dispersing the nanospheres in deionized water to prepare NH2-MIL-125(Ti)@Fe3O4A dispersion liquid; weighing a certain amount of metal M salt, and dissolving the metal M salt in deionized water to prepare a metal M salt solution; respectively dripping the metal M salt solution into the magnetic NH under stirring2-MIL-125(Ti)@Fe3O4Fully stirring the nano-sphere dispersion liquid, and then carrying out ultrasonic treatment for 30-50 min under the ultrasonic power of 60-100W to finish the metal M ions and the shell NH2pendant-NH in MIL-125(Ti)2The complex is then washed with deionized water and ethanol, respectively, and vacuum dried, e.g., at 50 deg.C for 8 hours, to obtain the magnetic M → NH2-MIL-125(Ti)@Fe3O4Nanospheres;
(4) magnetic M → TiO2@Fe3O4Preparing a catalyst: magnetic M → TiO2@Fe3O4Preparing a catalyst: weighing a certain amount of magnetic M → NH2-MIL-125(Ti)@Fe3O4Placing the nanospheres into a tubular reactor, roasting at room temperature to (320-380 ℃) under the air atmosphere with a certain flow rate at a programmed temperature, and keeping roasting at 320-380 ℃ for 4-6 hours to obtain the prepared magnetic M → TiO2@Fe3O4A catalyst.
3. The method according to claim 2, wherein in step (2), Fe is contained in the solution A3O4The mass concentration of the active carbon is 5 to 10 percent; the mass concentration of the isopropyl titanate in the solution B is 5-10 percent; the mass concentration of the 2-amino terephthalic acid in the solution C is 5-10%.
4. The method of claim 2, wherein step (3) NH2-MIL-125(Ti)@Fe3O4NH in the dispersion2-MIL-125(Ti)@Fe3O4The mass concentration is 20-30%; the mass percentage concentration of the metal M in the metal M salt solution is 0.1-0.5%.
5. The method according to claim 2, wherein in the step (3), a certain amount of M metal salt is weighed and dissolved in deionized water to prepare a solution of one or more of the following: weighing a certain amount of chloroauric acid (HAuCl)4) Dissolving in deionized water to prepare a solution with the gold mass concentration of 0.1-0.5%; weighing a certain amount of palladium chloride (PdCl)2) Dissolving the palladium in deionized water to prepare a palladium solution with the mass concentration of 0.1-0.5 percent; weighing a certain amount of chloroplatinic acid (H)2PtCl6·6H2O) is dissolved in deionized water to prepare a solution with platinum mass concentration of 0.1-0.5%; weighing a certain amount of silver nitrate (AgNO)3) Dissolving in deionized water to prepare a solution with the silver mass concentration of 0.1-0.5%.
6. The method of claim 2, wherein step (1) comprises magnetic Fe3O4Preparing particles: FeCl is added3·6H2Dissolving O in deionized water to prepare FeCl310-15% of solution. Dissolving sodium acetate in ethylene glycol to prepare ethylene glycol solution with the mass content of the sodium acetate of 5-10%. At 30 ℃ with N2Under the protection and stirring conditions, FeCl is added3The solution was added dropwise to a glycol solution of sodium acetate in which FeCl was present3And sodium acetate in a mass ratio of 3: 1, after the dropwise addition, putting the mixed solution into a high-pressure kettle, crystallizing at 180 ℃ for 8 hours, naturally cooling, washing with deionized water and ethanol respectively, and drying at 60 ℃ in vacuum to obtain the prepared magnetic Fe3O4And (3) granules.
7. The process according to any one of claims 1 to 6, wherein the metal M is selected from at least one, preferably two, more preferably any one of Au and other three of Au, Pd, Pt and Ag, and the mass content of each metal is up to 0.1 wt% to 0.5 wt%, respectively.
8. A magnetic catalyst of a porous titanium oxide shell assembled with a monoatomic metal, characterized by being prepared according to the method of any one of claims 1 to 7.
9. Use of a porous titania shell prepared by the method of any one of claims 1 to 7 in the assembly of a monatomic bimetallic magnetic catalyst, in the one-step preparation of methyl formate from methanol in the liquid phase.
10. The use according to claim 9, the catalytic reaction is carried out in a stirred tank reactor, liquid methanol being used as starting material, magnetic M → TiO being added2@Fe3O4Such as Au-Pd (Au-Pt, Au-Ag) → TiO2@Fe3O4The bifunctional catalyst is added with H with the molar equivalent to that of methanol2O2Carrying out catalytic reaction to obtain the product methyl formate in one step.
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