CN114210313A - Preparation method of high-dispersion sepiolite mineral loaded Au monatomic catalyst - Google Patents
Preparation method of high-dispersion sepiolite mineral loaded Au monatomic catalyst Download PDFInfo
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- CN114210313A CN114210313A CN202111559014.3A CN202111559014A CN114210313A CN 114210313 A CN114210313 A CN 114210313A CN 202111559014 A CN202111559014 A CN 202111559014A CN 114210313 A CN114210313 A CN 114210313A
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- 239000004113 Sepiolite Substances 0.000 title claims abstract description 70
- 229910052624 sepiolite Inorganic materials 0.000 title claims abstract description 70
- 235000019355 sepiolite Nutrition 0.000 title claims abstract description 70
- 229910052500 inorganic mineral Inorganic materials 0.000 title claims abstract description 50
- 239000011707 mineral Substances 0.000 title claims abstract description 50
- 239000003054 catalyst Substances 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 239000006185 dispersion Substances 0.000 title claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000002270 dispersing agent Substances 0.000 claims abstract description 9
- 239000010931 gold Substances 0.000 claims description 64
- 235000010755 mineral Nutrition 0.000 claims description 44
- 239000000243 solution Substances 0.000 claims description 17
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- 239000002243 precursor Substances 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 7
- 239000000843 powder Substances 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 7
- 239000006228 supernatant Substances 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000005119 centrifugation Methods 0.000 claims description 5
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 238000001035 drying Methods 0.000 claims description 5
- 150000003839 salts Chemical class 0.000 claims description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical group [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- 238000009210 therapy by ultrasound Methods 0.000 claims description 4
- LWIHDJKSTIGBAC-UHFFFAOYSA-K tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 claims description 4
- 230000032683 aging Effects 0.000 claims description 3
- 239000012298 atmosphere Substances 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 claims description 3
- 235000019982 sodium hexametaphosphate Nutrition 0.000 claims description 3
- 239000007787 solid Substances 0.000 claims description 3
- 238000000967 suction filtration Methods 0.000 claims description 3
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims description 3
- -1 gold potassium chloride Chemical compound 0.000 claims description 2
- ZFGJFDFUALJZFF-UHFFFAOYSA-K gold(3+);trichloride;trihydrate Chemical compound O.O.O.Cl[Au](Cl)Cl ZFGJFDFUALJZFF-UHFFFAOYSA-K 0.000 claims description 2
- 239000000047 product Substances 0.000 claims description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 239000001488 sodium phosphate Substances 0.000 claims description 2
- 229910000404 tripotassium phosphate Inorganic materials 0.000 claims description 2
- 235000019798 tripotassium phosphate Nutrition 0.000 claims description 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 2
- 229910000406 trisodium phosphate Inorganic materials 0.000 claims description 2
- 235000019801 trisodium phosphate Nutrition 0.000 claims description 2
- 239000011148 porous material Substances 0.000 abstract description 18
- 238000005342 ion exchange Methods 0.000 abstract description 16
- 230000007547 defect Effects 0.000 abstract description 7
- 230000008569 process Effects 0.000 abstract description 6
- 238000007598 dipping method Methods 0.000 abstract description 4
- 238000000464 low-speed centrifugation Methods 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000011946 reduction process Methods 0.000 abstract description 3
- 150000002500 ions Chemical class 0.000 description 11
- 239000002121 nanofiber Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052625 palygorskite Inorganic materials 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 230000004075 alteration Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 239000006229 carbon black Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 229910021389 graphene Inorganic materials 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 230000036647 reaction Effects 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000005476 size effect Effects 0.000 description 2
- 239000003039 volatile agent Substances 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 229910003771 Gold(I) chloride Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000000231 atomic layer deposition Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- FDWREHZXQUYJFJ-UHFFFAOYSA-M gold monochloride Chemical compound [Cl-].[Au+] FDWREHZXQUYJFJ-UHFFFAOYSA-M 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
- ZADYMNAVLSWLEQ-UHFFFAOYSA-N magnesium;oxygen(2-);silicon(4+) Chemical compound [O-2].[O-2].[O-2].[Mg+2].[Si+4] ZADYMNAVLSWLEQ-UHFFFAOYSA-N 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/30—Ion-exchange
-
- 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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/16—Clays or other mineral silicates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/48—Silver or gold
- B01J23/52—Gold
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/391—Physical properties of the active metal ingredient
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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
- B01J35/58—Fabrics or filaments
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
- B01J37/0207—Pretreatment of the support
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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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/02—Impregnation, coating or precipitation
- B01J37/0201—Impregnation
- B01J37/0213—Preparation of the impregnating solution
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- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Dispersion Chemistry (AREA)
- Catalysts (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
The invention relates to a preparation method of a high-dispersion sepiolite mineral load Au monatomic catalyst. The method comprises the steps of firstly dispersing and unbinding sepiolite family minerals by adding an inorganic dispersant, then removing sepiolite family mineral clusters with poor dispersibility through low-speed centrifugation, enabling the sepiolite family minerals with high dispersibility prepared by the method to expose more ion exchange sites, and then reducing the size of Au-containing ion groups by adjusting the pH value of a solution in the dipping process, so that the Au-containing ion groups can enter pore channels of the sepiolite family minerals through ion exchange more easily, and the size of the pore channels controls the growth size of the exchanged Au-containing ion groups in the reduction process, so that Au stably exists in a monatomic form. The invention not only overcomes the defects of low atom utilization rate, poor selectivity and stability of the traditional Au catalyst, but also overcomes the defects of complex preparation and processing technology and high cost of the single atom catalyst carrier.
Description
Technical Field
The technical scheme of the invention relates to the field of catalyst synthesis, in particular to a preparation method of a sepiolite mineral loaded Au monatomic catalyst.
Background
Catalysts hold an important position in the modern chemical industry. About more than 90% of industrial processes use catalysts, such as chemical, petrochemical, biochemical, environmental protection, etc. In which Au is widely used for CO oxidation and NO oxidation as a common noble metal catalystxReduction of hydrocarbons and organic Volatiles (VOCs), low temperature water gas shift reactions, novel fuel cell reactions, and the like.
The price of gold is high, the utilization rate of Au is improved, Au waste can be effectively avoided in the chemical industry, and the cost is reduced. The utilization efficiency of atoms in the Au monatomic catalyst can reach 100% theoretically, and the single active site and the strong acting force between the single active site and the carrier also cause good selectivity and stability. In conclusion, the Au monatomic catalyst can reduce the cost and has better catalytic activity, selectivity and stability. Therefore, the search for a simple and low-cost method for preparing the monatomic Au-based catalyst is of great significance.
The full harmonize topic group (Nano Energy,2020,69:104409) proposed a method of making monoatomic molecules using steric confinement, which first made K-ion intercalated g-C3N4Subsequently, Pt is taken into g-C by exchanging Pt ions with ions3N4And the size of Pt growth is limited through the interlayer spacing (0.3nm) so that the Pt stably exists in a single atom form, but the preparation process needs long-time high-temperature treatment and consumes large energy. The Xuverlin team (Angewandte Chemie,2019,131(4):1175-Method, first of all by hydrothermal modification and H2O2The method comprises the steps of introducing defects on the surface of commercial carbon black through etching, capturing and anchoring Pt monoatomic atoms through the defects, and finally forming stable coordination between Pt and C through high-temperature pyrolysis to enable Pt to exist stably in a monoatomic form, but the carbon black is high in cost and complex in carbon black treatment process. The Lu group (Nature communications,2018,9:3197) developed a method for controllable preparation of monoatomic atoms by using an atomic layer deposition method, which employs graphene as a substrate, deposits Co on the surface of the graphene after O3 treatment, and stably exists Co in a monoatomic form through strong coordination with the graphene. CN112275303A provides a MAX group ceramic powder as a carrier, which is exchanged with molten metal so that metal enters the carrier and is dispersed in a monoatomic form, although a cheap ceramic matrix is used as the carrier, ion exchange can only be carried out with the molten metal at high temperature, and the energy consumption is high, which is not beneficial to actual production.
The sepiolite mineral is an ideal environment material, has rich reserves, low price, small influence on ecological environment, high regeneration cycle utilization rate, excellent service performance and environmental harmony. It mainly comprises sepiolite and palygorskite, and has rich pore canal structure (theoretical pore diameter: sepiolite is
The palygorskite is
). Taking sepiolite as an example, the sepiolite is a hydrous magnesium silicate clay mineral, the main chemical components are silicon and magnesium, and the general formula of the chemical structure is Mg8[Si12O30](OH)4(OH2)4·8H2And O. The crystal structure unit is composed of two layers of silicon-oxygen tetrahedron and one layer of octahedron between them, and it has
Is provided with an opening structure. The pore channel structure of the sepiolite nano-fiber contains Mg and Al ions which can exchange with Au ions, and
the open pore structure of (a) can limit the size of Au, so that Au exists in the sepiolite in a monoatomic form. Similarly, Mg and Al ions in palygorskite can also be exchanged for Au ions (radicals), which
The pore size of (2) also ensures that Au is dispersed in the palygorskite in a monoatomic form. However, because the sepiolite group minerals are often agglomerated into bundles or even lumps in a natural state, which results in less exposed ion exchange sites, the sepiolite group minerals need to be dispersed and deagglomerated to expose more ion exchange sites, so as to improve the ion exchange efficiency.
Disclosure of Invention
The invention aims to provide a preparation method of a high-dispersion sepiolite mineral loaded Au monatomic catalyst aiming at the defects in the prior art. The method comprises the steps of firstly dispersing and unbinding sepiolite family minerals by adding an inorganic dispersant, then removing sepiolite family mineral clusters with poor dispersibility through low-speed centrifugation, enabling the sepiolite family minerals with high dispersibility prepared by the method to expose more ion exchange sites, and then reducing the size of Au-containing ion groups by adjusting the pH value of a solution in the dipping process, so that the Au-containing ion groups can enter pore channels of the sepiolite family minerals through ion exchange more easily, and the size of the pore channels controls the growth size of the exchanged Au-containing ion groups in the reduction process, so that Au stably exists in a monatomic form. The invention not only overcomes the defects of low atom utilization rate, poor selectivity and stability of the traditional Au catalyst, but also overcomes the defects of complex preparation and processing technology and high cost of the single atom catalyst carrier.
The technical scheme adopted by the invention for solving the technical problem is as follows:
a preparation method of a high-dispersion sepiolite mineral supported Au monatomic catalyst comprises the following steps:
(1) immersing sepiolite minerals in deionized water, adding an inorganic dispersant, adjusting the pH of the mixed solution to 3-7 by using hydrochloric acid, then placing the mixed solution in a high-speed stirrer, stirring at the rotating speed of 600-2500 rpm/min for 1-5 h, and then carrying out ultrasonic treatment for 0.5-2 h;
(2) placing the mixed liquid obtained in the step (1) in a low-speed centrifuge for centrifugation for 1-5 min, and discarding the bottom solid while retaining the supernatant liquid;
(3) repeating the operation of the step (2) for 1-3 times, and placing the finally obtained supernatant liquid into an oven for drying at 60-120 ℃ after suction filtration and washing to obtain the high-dispersion sepiolite minerals;
(4) adding the high-dispersion sepiolite mineral powder obtained in the step (3) into an Au salt solution, adjusting the pH value of the solution to 7-12, stirring and ultrasonically aging at room temperature for 1-12 hours; then washing the product until the washing liquid is neutral, and drying to obtain an Au precursor;
wherein the pH regulator is sodium carbonate, sodium bicarbonate or sodium hydroxide solution;
(5) putting the precursor obtained in the step (4) into a tubular atmosphere furnace, and introducing H2/N2And reducing the mixed gas for 1-4 h at 100-400 ℃ to obtain the highly dispersed sepiolite mineral supported Au monatomic catalyst.
The dispersing agent in the step (1) is sodium hexametaphosphate, trisodium phosphate or tripotassium phosphate, and the mass ratio of the dispersing agent to the sepiolite group minerals is 1: 10-1: 100.
The rotating speed of the step (2) is 1000-2500 rpm/min.
The Au salt in the step (4) is chloroauric acid, gold chloride trihydrate or gold potassium chloride; the concentration of the Au salt solution is 0.1-2 mmol/L.
The mass ratio of the Au salt in the step (4) to the highly dispersed sepiolite mineral is 1: 10-1: 100.
The preparation method of the high-dispersion sepiolite mineral supported Au monatomic catalyst is obtained by known methods from other raw materials, reagents and equipment except the sepiolite mineral, and the operation process can be mastered by a person skilled in the art.
The invention has the substantive characteristics that:
the method comprises the steps of firstly, additionally adding an inorganic dispersant to enable sepiolite family minerals to be deagglomerated, then, removing sepiolite family mineral clusters with poor dispersibility through low-speed centrifugation, enabling the highly dispersible sepiolite family minerals prepared through the method to expose more ion exchange sites so as to improve ion exchange efficiency, and then, adjusting dissolution pH in the dipping process to reduce the size of Au-containing ion groups, enabling the Au-containing ion groups to enter pore channels of the sepiolite family minerals more easily through ion exchange, controlling the size of the pore channels to control the growth size of the exchanged Au-containing ion groups in the reduction process, and enabling Au to exist stably in a monoatomic form.
The invention has the beneficial effects that: compared with the prior art, the invention has the following prominent substantive characteristics and remarkable progress:
(1) the size of Au is limited by utilizing the pore size effect of the sepiolite group minerals, so that the Au is uniformly distributed in the sepiolite group minerals in a monoatomic form, the atom utilization rate of the Au is improved, and the consumption of the Au is reduced.
(2) The present invention uses sepiolite mineral as carrier, which can be formed naturally, and has rich reserves in nature and low cost.
(3) The invention has simple processing technique for the sepiolite, does not need high-temperature cracking, has low energy consumption and is suitable for industrial production.
(4) The invention adopts a simple dipping method to prepare the monatomic catalyst, has simple process, does not need precise equipment and has higher inclusion for experimental parameters.
(5) The sepiolite mineral adopted by the invention can be subjected to ion exchange with metal salt at normal temperature, and has a naturally formed pore channel structure which can limit the size of metal.
(6) The sepiolite mineral has the advantages of low cost, abundant resources, etc., and can be widely used in chemical industry, petrochemical industry, etc,Oxidation of CO and NO in the fields of biochemistry, environmental protection and the likexReduction of hydrocarbons and organic Volatiles (VOCs), low temperature water gas shift reactions, and novel fuel cell reactions.
Drawings
FIG. 1 is a high-resolution transmission electron microscope image of spherical aberration corrected high-angle dark field image of the monoatomic Au/sepiolite nanofiber catalyst prepared in example 1;
FIG. 2 is a transmission electron microscope image of spherical aberration corrected high-angle dark field image of Au/sepiolite nanofiber catalyst prepared in comparative example 1;
Detailed Description
The invention will now be illustrated by means of specific examples, without restricting its scope to these examples.
The sepiolite mineral is a known material, and specifically is sepiolite or palygorskite. Sepiolite was used in the following examples. But is not limited thereto.
Example 1
Weighing 1000mg of sepiolite nanofiber powder (100 meshes) and immersing the sepiolite nanofiber powder in 100ml of deionized water, adding 150mg of sodium hexametaphosphate, adjusting the pH value of the solution to 5 by using 0.1mol/L hydrochloric acid solution, stirring the mixed solution in a high-speed stirrer at 2000rpm/min for 2 hours, and then carrying out ultrasonic treatment for 1 hour; placing the mixed solution in a low-speed centrifuge, centrifuging at 2000rpm/min for 3min, retaining the supernatant, and discarding the bottom solid precipitate; repeating the centrifugation for 2 times, carrying out suction filtration and washing on the obtained supernatant, and then putting the supernatant into a drying oven to be dried for 12 hours at 80 ℃, thus obtaining highly dispersed sepiolite nanofiber powder; weighing 99ml of deionized water, placing the deionized water in a beaker, adding 1ml of 0.025mmol/ml chloroauric acid solution, stirring for 15min, adding 500mg of processed sepiolite nanofiber powder, adjusting the pH value of the solution to 11 by using 1mol/L sodium hydroxide solution, continuously stirring for 1h at the speed of 700rpm/min, carrying out ultrasound treatment for 1h, and aging for 2h at room temperature; then, the precursor is filtered and washed until the washing liquid is neutral, and then the precursor is dried for 12 hours at 80 ℃ to prepare the precursor. Putting the precursor into a quartz boat, putting the quartz boat into a tubular atmosphere furnace, and introducing 5% H2+95％N2(volume ratio) of the mixed gas, the temperature rise rate is 2 ℃And (5) increasing the temperature to 200 ℃ in min, preserving the heat for 1h, and naturally cooling to room temperature to finish the preparation of the catalyst.
Fig. 1 is a high-resolution transmission electron microscope image of a spherical aberration corrected high-angle dark field image of the prepared monatomic Au/sepiolite nanofiber catalyst obtained in the example, and the area marked by a circle in the image is an Au monatomic signal (bright spot), so that the stable existence of Au in the catalyst in a monatomic form can be illustrated.
Example 2
The procedure is as in example 1, except that "1 ml of a 0.025mmol/ml chloroauric acid solution" is replaced by "1 ml of a 0.1mmol/ml chloroauric acid solution".
The obtained monatomic Au/sepiolite nanofiber catalyst with higher loading capacity shows that the sepiolite pore channel has good confinement effect, and the growth of Au monatomic into Au particles is avoided by properly increasing the concentration of chloroauric acid solution.
Comparative example 1
The other steps were the same as in example 1 except that "centrifugation at 2000 rpm/min" was replaced with "centrifugation at 500 rpm/min".
In comparative example 1, the low speed centrifugation did not remove the agglomerated sepiolite family fiber bundles, resulting in some of the subsequently dissociated fibers also re-binding to the agglomerated nano-bundles, greatly reducing the number of exposed ion exchange sites and ion exchange efficiency. It can be seen from fig. 2 that when the ion exchange sites are reduced, the ion exchange efficiency is reduced, Au is difficult to enter the pore channels of sepiolite, so that the size of Au cannot be limited, and Au grows into nanoparticles.
Comparative example 2
The other steps were the same as in example 1 except that "the pH of the solution was adjusted to 11 with 1mol/L sodium hydroxide solution" was replaced with "the pH of the solution was adjusted to 5 with 1mol/L hydrochloric acid solution".
The obtained Au/sepiolite composite material has no Au monoatomic signal basically, and a small amount of Au nano-particles exist on the surface of the sepiolite, because in comparative example 2, chloroauric acid is dissociated into [ AuCl ] in an acidic aqueous solution4]-Large ionic radius and difficult to cross with sepioliteAnd the metal ions enter the pore channel, so that the growth size of the pore channel cannot be limited, and the metal ions grow into Au nano particles.
It can be seen from the above examples and comparative examples that the sepiolite group mineral supported Au monatomic catalyst is prepared by a simple impregnation method on the basis of modification of the sepiolite group mineral, and the size of Au is limited by using the pore size effect of the sepiolite group mineral, so that Au is uniformly distributed in the sepiolite group mineral in a monatomic form. The preparation method has simple preparation process, adopts natural minerals with abundant reserves as carriers, and has low price.
The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
The invention is not the best known technology.
Claims (4)
1. A preparation method of a high-dispersion sepiolite mineral supported Au monatomic catalyst is characterized by comprising the following steps:
(1) immersing sepiolite minerals in deionized water, adding an inorganic dispersant, adjusting the pH of the mixed solution to 3-7 by using hydrochloric acid, then placing the mixed solution in a high-speed stirrer, stirring at the rotating speed of 600-2500 rpm/min for 1-5 h, and then carrying out ultrasonic treatment for 0.5-2 h;
wherein the mass ratio of the dispersing agent to the sepiolite mineral is 1: 10-1: 100;
(2) placing the mixed liquid obtained in the step (1) in a low-speed centrifuge for centrifugation for 1-5 min, and discarding the bottom solid while retaining the supernatant liquid;
(3) repeating the operation of the step (2) for 1-3 times, and placing the finally obtained supernatant liquid into an oven for drying at 60-120 ℃ after suction filtration and washing to obtain the high-dispersion sepiolite minerals;
(4) adding the high-dispersion sepiolite mineral powder obtained in the step (3) into an Au salt solution, adjusting the pH value of the solution to 7-12, stirring and ultrasonically aging at room temperature for 1-12 hours; then washing the product until the washing liquid is neutral, and drying to obtain an Au precursor;
wherein the pH regulator is sodium carbonate, sodium bicarbonate or sodium hydroxide solution; the mass ratio of the Au salt to the high-dispersion sepiolite minerals is 1: 10-1: 100;
(5) putting the precursor obtained in the step (4) into a tubular atmosphere furnace, and introducing H2/N2And reducing the mixed gas for 1-4 h at 100-400 ℃ to obtain the highly dispersed sepiolite mineral supported Au monatomic catalyst.
2. The method for preparing highly dispersed sepiolite-group mineral supported Au monatomic catalyst in accordance with claim 1, wherein the dispersant in the step (1) is sodium hexametaphosphate, trisodium phosphate or tripotassium phosphate.
3. The preparation method of the highly dispersed sepiolite mineral supported Au monatomic catalyst according to claim 1, wherein the rotation speed in the step (2) is between 1000 and 2500 rpm/min.
4. The method for preparing highly dispersed sepiolite mineral supported Au monatomic catalyst according to claim 1, wherein the Au salt of the step (4) is chloroauric acid, gold chloride trihydrate or gold potassium chloride; the concentration of the Au salt solution is 0.1-2 mmol/L.
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| JPH04363138A (en) * | 1991-04-03 | 1992-12-16 | Toyota Central Res & Dev Lab Inc | Oxidation catalyst |
| CN106881092A (en) * | 2017-04-25 | 2017-06-23 | 河北工业大学 | A kind of preparation method of load type metal Raney nickel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH04363138A (en) * | 1991-04-03 | 1992-12-16 | Toyota Central Res & Dev Lab Inc | Oxidation catalyst |
| CN106881092A (en) * | 2017-04-25 | 2017-06-23 | 河北工业大学 | A kind of preparation method of load type metal Raney nickel |
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