CN114029054B - Preparation method of acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst - Google Patents
Preparation method of acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst Download PDFInfo
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- CN114029054B CN114029054B CN202111559330.0A CN202111559330A CN114029054B CN 114029054 B CN114029054 B CN 114029054B CN 202111559330 A CN202111559330 A CN 202111559330A CN 114029054 B CN114029054 B CN 114029054B
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- 239000004113 Sepiolite Substances 0.000 title claims abstract description 67
- 229910052624 sepiolite Inorganic materials 0.000 title claims abstract description 67
- 235000019355 sepiolite Nutrition 0.000 title claims abstract description 67
- 239000003054 catalyst Substances 0.000 title claims abstract description 29
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 45
- 239000011707 mineral Substances 0.000 claims abstract description 45
- 238000000034 method Methods 0.000 claims abstract description 18
- 239000002253 acid Substances 0.000 claims abstract description 15
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 7
- 239000000243 solution Substances 0.000 claims description 20
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 9
- 239000002243 precursor Substances 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 4
- 230000004048 modification Effects 0.000 claims description 4
- 238000012986 modification Methods 0.000 claims description 4
- 239000012266 salt solution Substances 0.000 claims description 4
- 230000032683 aging Effects 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- 238000000967 suction filtration Methods 0.000 claims description 3
- 238000009210 therapy by ultrasound Methods 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 2
- 239000003929 acidic solution Substances 0.000 claims description 2
- 229910021529 ammonia Inorganic materials 0.000 claims description 2
- KZLHPYLCKHJIMM-UHFFFAOYSA-K iridium(3+);triacetate Chemical compound [Ir+3].CC([O-])=O.CC([O-])=O.CC([O-])=O KZLHPYLCKHJIMM-UHFFFAOYSA-K 0.000 claims description 2
- 229910017604 nitric acid Inorganic materials 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims 1
- 239000011148 porous material Substances 0.000 abstract description 22
- 238000005342 ion exchange Methods 0.000 abstract description 6
- 150000001450 anions Chemical group 0.000 abstract description 5
- 159000000009 barium salts Chemical class 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract description 3
- 238000005516 engineering process Methods 0.000 abstract description 3
- 238000011946 reduction process Methods 0.000 abstract description 3
- 239000011777 magnesium Substances 0.000 description 8
- 239000002121 nanofiber Substances 0.000 description 7
- 230000000052 comparative effect Effects 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
- 230000008569 process Effects 0.000 description 5
- YNJJJJLQPVLIEW-UHFFFAOYSA-M [Ir]Cl Chemical compound [Ir]Cl YNJJJJLQPVLIEW-UHFFFAOYSA-M 0.000 description 4
- 238000004873 anchoring Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 238000006555 catalytic reaction Methods 0.000 description 3
- 229910000420 cerium oxide Inorganic materials 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003575 carbonaceous material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052741 iridium Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 230000005476 size effect Effects 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- BJHMLLOSYSFSAV-UHFFFAOYSA-N Cl[Cl][Ir] Chemical compound Cl[Cl][Ir] BJHMLLOSYSFSAV-UHFFFAOYSA-N 0.000 description 1
- 238000010499 C–H functionalization reaction Methods 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
- 238000000137 annealing Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000003421 catalytic decomposition reaction Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000010335 hydrothermal treatment Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 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
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002135 nanosheet Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 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
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000004627 transmission electron microscopy Methods 0.000 description 1
Classifications
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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
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/58—Platinum group metals with alkali- or alkaline earth metals
-
- B01J35/391—
-
- 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
- B01J37/08—Heat treatment
- B01J37/10—Heat treatment in the presence of water, e.g. steam
-
- 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
Abstract
The invention relates to a preparation method of an Ir single-atom catalyst loaded by an acid-barium-modified sepiolite group mineral. The method comprises the steps of firstly treating sepiolite family minerals through an acid-hydrothermal method, and enabling H to be formed under the premise of not damaging pore channel structures of the sepiolite family minerals by using proper acid concentration and hydrothermal temperature + Displacing part of Mg with weaker exchange capacity 2+ H in the mineral at this time + The Ir is easier to replace, then the isoelectric point of the surface of the Ir is raised by barium salt treatment, and the affinity of the Ir to the Ir-containing anion group is enhanced, so that the Ir-containing group is easier to enter the pore canal of the sepiolite mineral by ion exchange, and the size of the pore canal controls the growth size of the exchanged Ir in the reduction process, so that the Ir exists stably in a single atom form. The invention overcomes the defects of low atom utilization rate, poor selectivity and stability of the traditional Ir catalyst, complex preparation and processing technology of the single-atom catalyst carrier and high cost.
Description
Technical Field
The technical scheme of the invention relates to the field of catalyst synthesis, in particular to a preparation method of sepiolite mineral loaded Ir monoatomic catalyst.
Background
Ir is one of the rarest elements in the earth's crust, and the average mass fraction is only one part per million, thus being very expensive. The Ir-based catalyst is successfully applied to the catalysis process in the fields of national defense, energy and environmental protection due to the characteristic of the Ir-based catalyst in the catalytic decomposition reaction of nitrogen-containing compounds. The Ir participates in the catalytic reaction in a single atom form, so that the use efficiency of the Ir atom is greatly improved (the theoretical efficiency can reach 100 percent), the stability of the Ir is improved by utilizing the strong interaction between the Ir and the carrier, and the catalytic performance and the stability are improved while the cost is reduced.
CN111804298A relates to a mayenite anchoring noble metal monoatomic catalyst rich in sub-nanometer cavity, which firstly synthesizes mayenite C by using a hydrothermal method 12 A 7 And then, adopting a vacuum impregnation method and high-temperature annealing heat treatment, and utilizing the confinement effect of the sub-nanometer cavity of the mayenite to ensure that noble metal is stably stored in a single atom form, wherein the preparation of the mayenite requires a long-time hydrothermal reaction and high-temperature heat treatment, so that the energy consumption is high. CN109225301B provides a method for preparing a monoatomic catalyst by electrochemical deposition, which uses CoFeSe nanosheets as a matrix, deposits Ir on the matrix in a monoatomic form through a three-electrode working system in an electrolyte containing Ir salt, but the deposition process requires strict control of experimental parameters (such as potential, sweep rate, and number of scans). CN112191246a discloses a method for preparing O vacancy anchoring monoatoms by using cerium oxide, firstly preparing cerium oxide containing O vacancies through hydrothermal and heat treatment in a specific atmosphere, then anchoring metal salt on the O vacancies on the surface of the cerium oxide by adopting an impregnation method, preparing a metal precursor, and finally reducing the precursor in hydrogen at a low temperature, wherein hydrogen also reduces part of the carrier in the reaction process, so that the carrier is lost. CN109939712a provides a surface-modified activated carbon-anchored metal monoatomic catalyst, in which the surface of activated carbon is first modified by high-temperature pyrolysis of nitride, and then metal is anchored on a carbon material in the form of monoatomic atoms by adding metal salts and reducing agents, but the price of the carbon material is relatively high, and a large amount of chemical reagents are used for preparing the catalyst, so that the process is complex, and the actual production is not facilitated.
The sepiolite group mineral is an ideal environment material, has rich reserves, low price, small influence on ecological environment, high regeneration and recycling rate and excellent usability and environment harmony. It mainly comprises sepiolite and palygorskite, and has rich pore canal structure (theoretical pore diameter: sepiolite isPalygorskite is->). Sepiolite is taken as an example, and is an aqueous magnesium silicate clay mineral, the main chemical components are silicon and magnesium, and the chemical structural general formula is Mg 8 [Si 12 O 30 ](OH) 4 (OH 2 ) 4 ·8H 2 O. The crystal structure unit is composed of two layers of silicon oxygen tetrahedron and one layer of octahedron interposed therebetween, and has +.>Is a porous structure of (a). The pore canal structure of sepiolite nanofiber contains Mg and Al ions which can be exchanged with Ir ions, and +.>The open cell structure of (2) can limit the size of Ir so that Ir is present in the sepiolite as a single atom. Similarly, the Mg and Al ions in palygorskite can also be exchanged with Ir ions, which are +.>The pore size of (2) also ensures that Ir is dispersed in the palygorskite as a single atom. However, the sepiolite group mineral has poor Mg ion exchange capability and negative surface electronegativity is unfavorable for anion (group) exchange, which results in lower ion exchange efficiency under natural conditions, so that modification is needed to improve the ion exchange efficiency.
Disclosure of Invention
The invention aims at overcoming the defects of the prior art and provides a preparation method of an acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst. The method comprises the steps of firstly treating sepiolite family minerals through an acid-hydrothermal method, and enabling H to be formed under the premise of not damaging pore channel structures of the sepiolite family minerals by using proper acid concentration and hydrothermal temperature + Displacing part of Mg with weaker exchange capacity 2+ H in the mineral at this time + Is easier to be replaced by Ir, and then the isoelectric point of the surface of the Ir-containing anion is increased by barium salt treatment, so that the affinity of the Ir-containing anion is enhanced, thereby leading to the Ir-containing group to be moreThe Ir is easy to enter the pore canal of sepiolite group mineral through ion exchange, and the size of the pore canal controls the growth size of the exchanged Ir in the reduction process, so that the Ir exists stably in a form of single atom. The invention overcomes the defects of low atom utilization rate, poor selectivity and stability of the traditional Ir catalyst, complex preparation and processing technology of the single-atom catalyst carrier and high cost.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the preparation method of the acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst comprises the following steps:
(1) Adding sepiolite group mineral into an acidic solution, stirring for 1-12 h at room temperature, and then placing the mixed solution into an oscillator to oscillate for 1-12 h;
(2) Transferring the mixed solution obtained in the step (1) into a reaction kettle, then placing the reaction kettle into an oven for hydrothermal reaction for 1-6 h, after cooling to room temperature, washing mineral powder in the reaction kettle until the washing solution is neutral, and fully drying at 60-120 ℃ to obtain the acid-combined hydrothermal modified sepiolite mineral powder;
(3) Immersing the sepiolite group mineral powder obtained in the step (2) and subjected to acid synergistic hydrothermal modification in 0.01-1 mmol/L BaCl 2 Stirring the solution for 1 to 12 hours at room temperature;
(4) Adding Ir salt solution into the mixed solution in the step (3), stirring and carrying out ultrasonic treatment, and aging for 1-12 h at room temperature; then carrying out suction filtration, washing and drying on the product to obtain an Ir precursor;
(5) Placing the precursor obtained in the step (4) in a tubular atmosphere furnace, and introducing H 2 /N 2 And (3) reducing the mixed gas at 100-400 ℃ for 1-4 hours to obtain the acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst.
The acid solution in the step (1) is hydrochloric acid, sulfuric acid or nitric acid solution, and the concentration of the acid solution is between 0.1 and 3 mol/L.
The hydrothermal temperature of the step (2) is between 60 and 180 ℃.
BaCl of the step (3) 2 Sepiolite family ore hydrothermally modified in coordination with acidThe mass ratio is 1:20-1:300.
The Ir salt in the step (4) is ammonia chloroiridate, an iridium chlorochloride acid hydrate or iridium acetate; ir salt solution is added into the mixed solution, and the concentration of Ir is 0.1-2 mmol/L.
The mass ratio of the Ir salt and the acid-combined barium-modified sepiolite mineral in the step (4) is 1:10-1:100.
The preparation method of the acid-barium-modified sepiolite-group mineral-supported Ir monoatomic catalyst is characterized in that other raw materials, reagents and equipment except for sepiolite-group minerals are obtained through known methods, and the operation process can be mastered by a person skilled in the art.
The invention has the substantial characteristics that:
the method comprises the steps of firstly treating sepiolite group minerals by an acid-hydrothermal method, and using proper acid concentration and hydrothermal temperature to enable H to be formed on the premise of not damaging pore channel structures of the sepiolite group minerals + Displacing part of Mg with weaker exchange capacity 2+ H in the mineral at this time + The Ir is easier to replace, then the isoelectric point of the surface of the Ir is raised by barium salt treatment, and the affinity of the Ir to the Ir-containing anion group is enhanced, so that the Ir-containing group is easier to enter the pore canal of the sepiolite mineral by ion exchange, and the size of the pore canal controls the growth size of the exchanged Ir in the reduction process, so that the Ir exists stably in a single atom form.
The beneficial effects of the invention are as follows: compared with the prior art, the invention has the following outstanding substantial characteristics and remarkable progress:
(1) The size of Ir is limited by utilizing the pore canal size effect of the sepiolite mineral, so that the Ir is uniformly distributed in the sepiolite mineral in a single-atom form, the atom utilization rate of the Ir is improved, and the dosage of the Ir is reduced.
(2) Compared with CN111804298A, the invention uses natural sepiolite group mineral as carrier, the pore canal size of the mineral can limit the noble metal to form single atom, the mineral reserves are abundant in the nature, the artificial synthesis is not needed, the treatment process is simple, and the energy consumption is low.
(3) Compared with CN109225301B, the invention has good inclusion for experimental parameters and no requirement for the conductivity of the carrier.
(4) In contrast to CN107537481B, the present invention does not lose carrier during the preparation process.
(5) Compared with CN109939712A, the sepiolite used in the invention has low price, less chemical reagents used for modifying the sepiolite and simple process.
(6) Compared with the Ir-Ir bond and the Ir-O (sepiolite family mineral) bond in the sepiolite loaded Ir particle, the sepiolite anchoring Ir single atom has only the Ir-O (sepiolite family mineral) bond, and the active site is single, thereby being beneficial to optimizing the selectivity of the reaction.
(7) The sepiolite family mineral has the advantages of low price, abundant resources and the like as the natural mineral, utilizes the natural mineral as the natural resource, saves the cost, and can be widely applied to the fields of energy, chemical industry and the like, such as Cativa catalysis, carbon-hydrogen bond activation, carbon dioxide reduction, propane dehydrogenation and the like.
Drawings
FIG. 1 is a high-resolution transmission electron microscope image of spherical aberration corrected high-angle dark field image of the monoatomic Ir/sepiolite nanofiber catalyst prepared in example 1;
FIG. 2 is a high angle dark field image transmission electron microscopy image of spherical aberration correction of the Ir/sepiolite nanofiber catalyst prepared in comparative example 1;
Detailed Description
The present invention will be described with reference to specific examples, but the scope of the present invention is not limited to these examples.
The sepiolite group mineral is a known material, and is specifically sepiolite or palygorskite. Sepiolite was used in the examples below. But is not limited thereto.
Example 1
600mg of sepiolite nanofiber powder (100 meshes) is weighed and immersed into 100ml of 0.5mol/L hydrochloric acid solution, and the mixture is stirred for 2 hours and then is continuously oscillated for 2 hours; transferring the mixed solution into a reaction kettle to react for 3 hours at 130 ℃, and after cooling to room temperature, separating mineral powder in the mixed solution and fully washing until the washing solution is neutral; putting the modified mineral powder into an oven to be dried for 8 hours at 100 ℃; formulation 99ml 0.1mmol/L BaCl 2 The aqueous solution was immersed by adding 500mg of the treated sepiolite nanofiber powder, stirring for 2 hours, adding 1ml of 0.025mmol/ml chloroiridium acid solution, stirring at 700rpm/min for 1 hour and ultrasonic treatment for 1 hour, aging at room temperature for 2 hours, suction filtration, washing, and drying at 80 ℃ for 12 hours to prepare the precursor. Placing the precursor into a quartz boat, placing into a tubular atmosphere furnace, and introducing 5%H 2 +95％N 2 And (3) mixing the gases at a heating rate of 5 ℃/min to 300 ℃, preserving heat for 1h, and naturally cooling to room temperature to finish the preparation of the catalyst.
Fig. 1 is a spherical aberration-corrected high-angle dark field image high-resolution transmission electron microscope image of the prepared monoatomic Ir/sepiolite nanofiber catalyst obtained in this example, and the area marked by circles in the figure is Ir monoatomic signal (bright spot), so that it can be explained that Ir in the catalyst exists stably in monoatomic form.
Example 2
The other procedure was as in example 1, except that "1 ml of 0.025mmol/ml chloroiridium acid solution was added" was replaced with "1 ml of 0.1mmol/ml chloroiridium acid solution was added".
The higher loading monatomic Ir/sepiolite nanofiber catalyst is obtained, which shows that the sepiolite pore canal has good domain-limiting effect, and the proper increase of the concentration of the chloroiridium acid solution can not lead Ir monatomic growth into Ir particles.
Comparative example 1
The other procedure is as in example 1, except that "immersed in 0.5mol/L hydrochloric acid solution" is replaced by "immersed in 4mol/L hydrochloric acid solution".
In comparative example 1, 4mol/L hydrochloric acid solution treatment of sepiolite resulted in an excess of Mg 2+ And the sepiolite falls off to destroy the pore canal structure of the sepiolite, so that the pore canal collapses. It can be seen from fig. 2 that Ir cannot be limited in size when the sepiolite pore structure is broken, and Ir grows into 1nm sized particles.
Comparative example 2
The other procedure is as in example 1, except that "reaction at 130℃for 3h" is replaced by "reaction at 200℃for 3h".
The Ir/sepiolite composite material obtained was essentially free of Ir monoatomic signals, and small amounts of Ir nanoparticles were present on the sepiolite surface, since in comparative example 2, too high a hydrothermal temperature resulted in a large excess of Mg 2+ Quilt H + Instead, the sepiolite pore canal collapses, so that Ir is difficult to enter the pore canal to be adsorbed on the sepiolite surface, and Ir nano particles are grown.
As can be seen from the above examples and comparative examples, the present invention prepares a sepiolite group mineral-supported Ir monoatomic catalyst by a simple impregnation method on the basis of modifying a sepiolite group mineral, and limits the size of Ir by using the pore size effect of the sepiolite group mineral, so that Ir is uniformly distributed in the sepiolite group mineral in a monoatomic form. The invention has simple preparation process, adopts natural minerals with abundant reserves as carriers and has low price.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
The invention is not a matter of the known technology.
Claims (2)
1. The preparation method of the acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst is characterized by comprising the following steps:
(1) Adding sepiolite group minerals into an acidic solution, stirring for 1-12 h at room temperature, and then placing the mixed solution into an oscillator to oscillate for 1-12 h;
(2) Transferring the mixed solution obtained in the step (1) into a reaction kettle, then placing the reaction kettle into an oven for hydrothermal reaction for 1-6 hours, after cooling to room temperature, washing mineral powder in the reaction kettle until the washing solution is neutral, and fully drying at 60-120 ℃ to obtain acid-combined hydrothermal modified sepiolite mineral powder;
(3) Immersing the sepiolite group mineral powder obtained in the step (2) through acid and hydrothermal modification in the solution of 0.01-1 mmol/L BaCl 2 Stirring the solution for 1-12 h at room temperature;
wherein, baCl 2 The mass ratio of the sepiolite mineral modified by combining with acid and water is 1:20-1:300;
(4) Adding Ir salt solution into the mixed solution in the step (3), stirring and aging at room temperature for 1-12 h after ultrasonic treatment; then carrying out suction filtration, washing and drying on the product to obtain an Ir precursor;
wherein the mass ratio of Ir salt to acid-barium-modified sepiolite mineral is 1:10-1:100;
(5) Placing the precursor obtained in the step (4) in a tubular atmosphere furnace, and introducing H 2 /N 2 Reducing the mixed gas at 100-400 ℃ to 1-4 h to obtain the acid-combined barium-modified sepiolite mineral-supported Ir monoatomic catalyst;
the acid solution in the step (1) is hydrochloric acid, sulfuric acid or nitric acid solution, and the concentration of the acid solution is 0.1-3 mol/L;
the hydrothermal temperature of the step (2) is 60-180 ℃;
and (3) adding an Ir salt solution into the mixed solution in the step (4), wherein the concentration of Ir is 0.1-2 mmol/L.
2. The method for preparing the acid-barium-modified sepiolite-group mineral-supported Ir monoatomic catalyst according to claim 1, wherein the Ir salt in the step (4) is ammonia chloroiridate, chloroiridate hydrate or iridium acetate.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111559330.0A CN114029054B (en) | 2021-12-20 | 2021-12-20 | Preparation method of acid-barium-modified sepiolite group mineral-supported Ir monoatomic catalyst |
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| CN109453762A (en) * | 2018-10-23 | 2019-03-12 | 湖南大学 | A kind of preparation method and application of modified clay mine loaded palladium catalyst |
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