CN118217998A - Catalyst for in-situ synthesis-supported high-entropy oxide and preparation method and application thereof - Google Patents
Catalyst for in-situ synthesis-supported high-entropy oxide and preparation method and application thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 58
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 17
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 239000011248 coating agent Substances 0.000 claims abstract description 38
- 238000000576 coating method Methods 0.000 claims abstract description 38
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 34
- 230000003197 catalytic effect Effects 0.000 claims abstract description 21
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 5
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 5
- 239000002002 slurry Substances 0.000 claims description 25
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 21
- 238000000034 method Methods 0.000 claims description 15
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 238000000498 ball milling Methods 0.000 claims description 12
- 239000000919 ceramic Substances 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 238000002407 reforming Methods 0.000 claims description 11
- 239000002243 precursor Substances 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 7
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 7
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 7
- 239000007789 gas Substances 0.000 claims description 6
- 239000011268 mixed slurry Substances 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 230000008569 process Effects 0.000 claims description 5
- 229910052721 tungsten Inorganic materials 0.000 claims description 5
- 229910052707 ruthenium Inorganic materials 0.000 claims description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 2
- 229910002651 NO3 Inorganic materials 0.000 claims description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 2
- 238000010306 acid treatment Methods 0.000 claims description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 2
- 238000005470 impregnation Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 229910052760 oxygen Inorganic materials 0.000 claims description 2
- 239000001301 oxygen Substances 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims 1
- 229910044991 metal oxide Inorganic materials 0.000 abstract description 12
- 150000004706 metal oxides Chemical class 0.000 abstract description 12
- 229910052799 carbon Inorganic materials 0.000 abstract description 8
- 238000006057 reforming reaction Methods 0.000 abstract description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 6
- 230000008021 deposition Effects 0.000 abstract description 6
- 238000011068 loading method Methods 0.000 abstract description 5
- 230000009286 beneficial effect Effects 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 6
- 238000007664 blowing Methods 0.000 description 6
- 229910017604 nitric acid Inorganic materials 0.000 description 6
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000009849 deactivation Effects 0.000 description 3
- 239000008367 deionised water Substances 0.000 description 3
- 229910021641 deionized water Inorganic materials 0.000 description 3
- 238000003618 dip coating Methods 0.000 description 3
- 239000005431 greenhouse gas Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 238000013112 stability test Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910000753 refractory alloy Inorganic materials 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000012720 thermal barrier coating 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
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/894—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
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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
- B01J37/0203—Impregnation the impregnation liquid containing organic compounds
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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
- B01J37/08—Heat treatment
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
- C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
- C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
- C01B3/40—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts characterised by the catalyst
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Abstract
The application discloses an in-situ synthesis-supported high-entropy oxide catalyst, and a preparation method and application thereof. The catalyst comprises a honeycomb carrier and a catalytic coating, wherein the catalytic coating is supported on the surface of the honeycomb carrier; the inner layer of the catalytic coating is an alumina coating; the outer layer of the catalytic coating is a high-entropy oxide coating. The catalyst has excellent high-temperature hydrothermal stability and carbon deposition resistance in methane/CO 2 reforming reaction, can keep high catalytic activity in high-temperature reducing atmosphere, and provides a thinking for catalyst development under high-temperature and high-temperature hydrothermal conditions. The application also provides an in-situ synthesis loading method of the high-entropy metal oxide with the integral honeycomb structure, which simplifies the preparation process, improves the technical economy and is beneficial to the industrial application of the technology.
Description
Technical Field
The application relates to a catalyst for in-situ synthesis-supported high-entropy oxide, and a preparation method and application thereof, and belongs to the field of catalytic material preparation.
Background
Carbon dioxide and methane are used as typical greenhouse gases, and the efficient conversion and recycling of the carbon dioxide and the methane are particularly important. The methane dry reforming reaction (DRM) can directly convert the two greenhouse gases into the synthetic gas, can reduce the energy consumption and simultaneously relieve the emission reduction pressure of the greenhouse gases, and has both environmental and economic benefits. However, the DRM reaction needs to be carried out under the high-temperature (700-850 ℃) and strong-reducibility reaction atmosphere, and the catalyst needs to have excellent sintering resistance, carbon deposit resistance and water resistance.
High Entropy Oxide (HEO) maintains a stable structure even under extreme use conditions due to the high entropy effect of thermodynamics and the delayed diffusion effect of kinetics. The high-entropy oxide has been widely paid attention from birth, and is expected to be applied to different fields such as high-entropy alloy (CN 109182877A), high-entropy alloy coating CN 103484810B), high-entropy ceramic (AU 2021102229A4, CN 111763087A), high-entropy semiconductor or insulator (TWI 395336B), corrosion-resistant coating (CN 108914041B, CN 108914041A), high-entropy oxide amorphous (CN 108821571B), high-heat-conducting material (WO 2022160471A 1), refractory alloy (CN 109182877B), high-electric conductivity (CN 113023777A), thermal barrier coating (SG 11202100226YA, EP3863990A2, CA3106049A1, WO2020142125A 3), electrochromic material (CN 112340787A) and ferromagnetic material (WO 2019109059A 1), and the related applications are mainly based on excellent heat conduction, electric conduction, corrosion resistance and other properties. And relatively few applications in the catalytic field, only (US 20220134316 A1) applied to CO catalytic oxidation reactions; patent CN111790397a discloses a high entropy metal oxide catalyst for removing aromatic organic sulfide in fuel oil by catalytic oxidation. The high entropy oxide has high thermal stability and heat conducting property, and the multi-component adjustability can solve the requirement of methane CO 2 reforming reaction on the high hydrothermal stability of the catalyst. In addition, the reaction is affected by heat and mass transfer, and the high mass transfer performance of the catalyst with the integral structure is beneficial to eliminating hot spots of a bed layer and avoiding the problem of carbon deposition caused by uneven temperature distribution. However, the conventional preparation process of the catalyst for synthesizing the high-entropy oxide and then loading the high-entropy oxide is complex, and the process flow can be simplified by adopting an in-situ synthesis loading method.
Disclosure of Invention
In order to overcome the problems that the dry reforming catalyst of methane has poor water-heat resistance and is easy to be deactivated by carbon deposition, the catalytic reaction is controlled by mass transfer and heat transfer, and the like, the invention discloses the dry reforming catalyst of methane with high entropy metal oxide, which has excellent water-heat stability and adjustable structural performance; meanwhile, the low diffusion resistance of the catalyst with the integral structure is utilized, so that the temperature gradient on the catalyst is avoided; the in-situ synthesis of the supported process also simplifies the catalyst preparation process. The technical problem to be solved is to provide a methane/CO 2 reforming catalyst with excellent hydrothermal stability and anti-carbon deposition and a preparation method thereof.
According to one aspect of the present application, there is provided an in situ synthesis-supported high entropy oxide catalyst comprising a honeycomb support and a catalytic coating supported on the surface of the honeycomb support;
The inner layer of the catalytic coating is an alumina coating;
The outer layer of the catalytic coating is a high-entropy oxide coating;
The high entropy oxide includes a first element and a second element;
the first element is selected from at least five of Mg, al, ce, la, sr, W, K, zr, mn, ba, si, nb, mo, nd, gd;
The second element is selected from at least one of Ni, co, ru, rh, ir, pt.
Optionally, the catalytic coating accounts for 5-20wt% of the mass of the catalyst.
Optionally, the alumina coating comprises 5 to 15wt% of the catalyst mass.
Optionally, the high entropy oxide coating comprises 5 to 10wt% of the catalyst mass.
Optionally, each element in the first element independently accounts for 5-50wt% of the mass of the high-entropy oxide.
Optionally, each element in the first element independently accounts for any value or a range of values between two values of 5wt%, 15wt%, 25wt%, 35wt%, 55wt% of the high entropy oxide mass.
Optionally, ru, rh, ir, pt elements in the second element independently account for 0-5 wt% of the mass of the high entropy oxide.
Optionally, ni or Co in the second element independently accounts for 5-50% of the mass of the high entropy oxide.
Optionally, ni or Co in the second element independently accounts for any value or range of values between 5wt%, 15wt%, 25wt%, 35wt%, 55wt% of the high entropy oxide mass.
Optionally, the molar ratio of the elements except Ru, rh, ir, pt in the high-entropy oxide is the same.
Optionally, the honeycomb support is selected from a ceramic honeycomb support and/or a metal honeycomb ceramic.
According to still another aspect of the present application, there is provided a method for preparing the above catalyst, comprising the steps of:
(1) Ball milling mixed slurry containing gamma-Al 2O3, pseudo-boehmite, al (OH) 3, polyvinyl alcohol, citric acid and water to obtain slurry A;
(2) Impregnating a honeycomb carrier into the slurry A, drying I, and roasting I in an oxygen-containing atmosphere to obtain an intermediate with an alumina coating;
(3) Immersing the intermediate with the alumina coating in a precursor solution containing a first element and a second element in an equal volume, drying II, and roasting II in a reducing atmosphere to obtain the catalyst;
Wherein the first element is selected from at least five of Mg, al, ce, la, sr, W, K, zr, mn, ba, si, nb, mo, nd, gd;
The second element is selected from at least one of Ni, co, ru, rh, ir, pt.
Optionally, the mass ratio of the gamma-Al 2O3 to the pseudo-boehmite to the Al (OH) 3 to the polyvinyl alcohol to the citric acid to the water is 1:0.1 to 0.5:0.2 to 1.0:0.5 to 2.0:0.05 to 0.2:2.0 to 4.0.
Optionally, the precursor solution containing the first element and the second element is selected from at least one of nitrate, hydrochloride and acetate containing the first element and the second element.
Optionally, the honeycomb support is selected from a ceramic honeycomb support and/or a metal honeycomb ceramic;
The honeycomb carrier is subjected to an acid treatment prior to use.
Optionally, in the step (1), the rotation speed of the ball milling is 300-800 r/min, and the time of the ball milling is 2-10 h.
Optionally, in step (1), the average particle size of the slurry a is 1.0 to 4.0 μm.
Optionally, in step (1), the pH of slurry a is 1.0 to 6.0.
Optionally, in the step (2), the time of the impregnation is 1 to 3 minutes.
Optionally, in the step (2), the temperature of the drying I is 100-150 ℃, and the time of the drying I is 2-10 h.
Optionally, in the step (2), the temperature of the roasting I is 600-900 ℃, and the time of the roasting I is 2-6 h.
Optionally, in the step (3), the temperature of the drying II is 100-150 ℃, and the time of the drying II is 2-10 h.
Optionally, in the step (3), the time of roasting II is 700-1100 ℃, and the time of roasting II is 2-8 h.
Optionally, the solid-to-liquid ratio of the honeycomb carrier to the slurry a is 1:1 to 3.
According to a further aspect of the present application there is provided the use of a catalyst as hereinbefore defined or obtainable according to a process as hereinbefore defined in the preparation of synthesis gas by reforming methane and CO 2.
The application has the beneficial effects that:
1) The catalyst for in-situ synthesis-loading high-entropy oxide provided by the application has a high-entropy oxide structure and excellent hydrothermal stability and anti-carbon deposition performance.
2) The catalyst for in-situ synthesis-loading high-entropy oxide provided by the application has the advantages that the high-entropy oxide is loaded on the honeycomb carrier with the alumina layer, the heat transfer and mass transfer of the catalyst with the integral structure are enhanced, and the strong endothermic catalytic reaction performance is improved.
3) The preparation method provided by the application has the advantages of simple process and easy engineering application.
4) The catalyst provided by the application has excellent hydrothermal stability and carbon deposition resistance in methane/CO 2 reforming reaction, and can maintain high catalytic activity in high-temperature reducing atmosphere.
Detailed Description
The present application is described in detail below with reference to examples, but the present application is not limited to these examples.
Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.
The CO 2 conversion, CH 4 conversion, and H 2 selectivity in the examples of the present application were calculated as follows:
CO 2 conversion is
CH 4 conversion was
H 2 Selectivity is
In the examples of the present application, the CO 2 conversion, CH 4 conversion, and H 2 selectivity were all calculated on a carbon mole basis.
Example 1:
The present example provides a method for preparing a monolithic honeycomb in situ synthesis-supported high entropy metal oxide methane/CO 2 reforming catalyst.
1. Gamma-Al 2O3, pseudo-boehmite, al (OH) 3, 5wt% polyvinyl alcohol aqueous solution, citric acid and deionized water according to the weight ratio of 1.0:0.2:0.6:0.5:0.15:2.5, mixing;
2. Ball milling the mixed slurry obtained in the step 1 on a high-energy ball mill, and ball milling for 5 hours at the rotating speed of 500 revolutions per minute to obtain slurry A; the average particle diameter (D50) of the slurry A is 2.0 microns, and the pH value range of the slurry A is adjusted to 4.0 by adding dilute nitric acid;
3. dip-coating a ceramic honeycomb carrier treated in 2% dilute nitric acid or a metal honeycomb carrier pretreated at a high temperature in the slurry prepared in the step 2 for 3 minutes, and blowing off the redundant slurry A by using compressed air to prepare a sample B; sample B was dried at 150 ℃ for 8 hours and weighed; repeating the step according to the coating quantity until reaching the target coating quantity;
4. then, baking in a muffle furnace at 800 ℃ under an air atmosphere for 6 hours to obtain a sample C coated with an inner layer, wherein the inner layer coating accounts for 10wt.% of the total catalyst weight;
5. According to the condition that the outer layer high-entropy metal oxide accounts for 5% of the weight of the whole catalyst, preparing Ni, mg, al, ce, si, la, co and a salt solution D of Ru precursor, wherein non-noble metal elements have the same mole number;
6. Immersing the catalyst C in the precursor solution D, and blowing off redundant solution by using compressed air;
7. Sample C impregnated with solution D was dried at 120deg.C for 10 hours;
8. Roasting the dried sample for 2 hours at 700 ℃ in an air atmosphere to prepare the catalyst E for in-situ synthesis-supported high-entropy metal oxide for standby.
Example 2:
The present example provides a method for preparing a monolithic honeycomb in situ synthesis-supported high entropy metal oxide methane/CO 2 reforming catalyst.
1. Gamma-Al 2O3, pseudo-boehmite, al (OH) 3, 5wt% polyvinyl alcohol aqueous solution, citric acid and deionized water according to the weight ratio of 1.0:0.2:0.6:0.5:0.15:2.5, mixing;
2. Ball milling the mixed slurry obtained in the step 1 on a high-energy ball mill, and ball milling for 5 hours at the rotating speed of 500 revolutions per minute to obtain slurry A; the average particle diameter (D50) of the slurry A is 2.0 microns, and the pH value range of the slurry A is adjusted to 4.0 by adding dilute nitric acid;
3. dip-coating a ceramic honeycomb carrier treated in 2% dilute nitric acid or a metal honeycomb carrier pretreated at a high temperature in the slurry prepared in the step 2 for 3 minutes, and blowing off the redundant slurry A by using compressed air to prepare a sample B; sample B was dried at 150 ℃ for 8 hours and weighed; repeating the step according to the coating quantity until reaching the target coating quantity;
4. then, roasting in a muffle furnace at 800 ℃ under an air atmosphere for 6 hours to obtain a sample C coated with an inner layer, wherein the inner layer catalytic coating accounts for 10wt.% of the total catalyst weight;
5. according to the condition that the outer layer high entropy metal oxide accounts for 5% of the weight of the whole catalyst, preparing Ni, sr, mn, mg, al, nd, ce, la and a salt solution D of Ru and Pt precursors, wherein non-noble metal elements have the same mole number;
6. Immersing the catalyst C in the precursor solution D, and blowing off redundant solution by using compressed air;
7. Sample C impregnated with solution D was dried at 120deg.C for 10 hours;
8. Roasting the dried sample for 2 hours at 700 ℃ in an air atmosphere to prepare the catalyst E for in-situ synthesis-supported high-entropy metal oxide for standby.
Example 3:
The present example provides a method for preparing a monolithic honeycomb in situ synthesis-supported high entropy metal oxide methane/CO 2 reforming catalyst.
1. Gamma-Al 2O3, pseudo-boehmite, al (OH) 3, 5wt% polyvinyl alcohol aqueous solution, citric acid and deionized water according to the weight ratio of 1.0:0.2:0.6:0.5:0.15:2.5, mixing;
2. Ball milling the mixed slurry obtained in the step 1 on a high-energy ball mill, and ball milling for 5 hours at the rotating speed of 500 revolutions per minute to obtain slurry A; the average particle diameter (D50) of the slurry A is 2.0 microns, and the pH value range of the slurry A is adjusted to 4.0 by adding dilute nitric acid;
3. dip-coating a ceramic honeycomb carrier treated in 2% dilute nitric acid or a metal honeycomb carrier pretreated at a high temperature in the slurry prepared in the step 2 for 3 minutes, and blowing off the redundant slurry A by using compressed air to prepare a sample B; sample B was dried at 150 ℃ for 8 hours and weighed; repeating the step according to the coating quantity until reaching the target coating quantity;
4. then, roasting in a muffle furnace at 800 ℃ under an air atmosphere for 6 hours to obtain a sample C coated with an inner layer, wherein the inner layer catalytic coating accounts for 10wt.% of the total catalyst weight;
5. According to the condition that the outer layer high entropy metal oxide accounts for 5% of the weight of the whole catalyst, preparing Ni, mg, al, ce, W, zr, ba, co and a salt solution D of Ru and Rh precursors, wherein non-noble metal elements have the same mole number;
6. Immersing the catalyst C in the precursor solution D, and blowing off redundant solution by using compressed air;
7. Sample C impregnated with solution D was dried at 120deg.C for 10 hours;
8. Roasting the dried sample for 2 hours at 700 ℃ in an air atmosphere to prepare the catalyst E for in-situ synthesis-supported high-entropy metal oxide for standby.
Application example 1:
the embodiment provides an application of a monolithic honeycomb loaded high-entropy oxide catalyst in methane/CO 2 reforming.
The monolithic catalyst prepared in example 1 was placed in a fixed bed reactor and the dry reforming reaction was carried out by heating to 650℃at a mixed gas flow rate of 100mL/min, CH 4/CO2/N2 =1/1/3. The conversion rates of CH 4 and CO 2 can reach 94% and 98%, respectively, and the selectivity of H 2 can reach 99%. After 48 hours of stability test, the activity is basically kept unchanged, and no deactivation phenomenon occurs.
Application example 2:
the embodiment provides an application of a monolithic honeycomb loaded high-entropy oxide catalyst in methane/CO 2 reforming.
The monolithic catalyst prepared in example 2 was placed in a fixed bed reactor, and the dry reforming reaction was carried out by heating to 700℃at a mixed gas flow rate of 100mL/min, CH 4/CO2/N2 =1/1/3. The conversion rates of CH 4 and CO 2 can reach 92% and 95%, respectively, and the selectivity of H 2 can reach 96%. After 48 hours of stability test, the activity is basically kept unchanged, and no deactivation phenomenon occurs.
Application example 3:
the embodiment provides an application of a monolithic honeycomb loaded high-entropy oxide catalyst in methane/CO 2 reforming.
The monolithic catalyst prepared in example 2 was placed in a fixed bed reactor, and the dry reforming reaction was carried out by heating to 700℃at a mixed gas flow rate of 100mL/min, CH 4/CO2/N2 =1/1/3. The conversion rates of CH 4 and CO 2 can reach 97% and 95%, respectively, and the selectivity of H 2 can reach 99%. After 48 hours of stability test, the activity is basically kept unchanged, and no deactivation phenomenon occurs.
While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.
Claims (10)
1. The catalyst for in-situ synthesis-supported high-entropy oxide is characterized by comprising a honeycomb carrier and a catalytic coating, wherein the catalytic coating is supported on the surface of the honeycomb carrier;
The inner layer of the catalytic coating is an alumina coating;
The outer layer of the catalytic coating is a high-entropy oxide coating;
The high entropy oxide includes a first element and a second element;
the first element is selected from at least five of Mg, al, ce, la, sr, W, K, zr, mn, ba, si, nb, mo, nd, gd;
The second element is selected from at least one of Ni, co, ru, rh, ir, pt.
2. The catalyst according to claim 1, wherein the catalytic coating comprises 5 to 20wt% of the catalyst mass;
preferably, the alumina coating accounts for 5-15 wt% of the mass of the catalyst;
preferably, the high entropy oxide coating accounts for 5-10wt% of the catalyst mass;
preferably, each element in the first element independently accounts for 5-50wt% of the mass of the high-entropy oxide;
Preferably, ru, rh, ir, pt elements in the second element independently account for 0-5 wt% of the mass of the high entropy oxide;
Preferably, ni or Co in the second element independently accounts for 5-50wt% of the mass of the high-entropy oxide;
preferably, the molar ratio of elements except Ru, rh, ir, pt in the high-entropy oxide is the same;
Preferably, the honeycomb support is selected from ceramic honeycomb supports and/or metal honeycomb ceramics.
3. A method for preparing the catalyst according to claim 1 or 2, comprising the steps of:
(1) Ball milling mixed slurry containing gamma-Al 2O3, pseudo-boehmite, al (OH) 3, polyvinyl alcohol, citric acid and water to obtain slurry A;
(2) Impregnating a honeycomb carrier into the slurry A, drying I, and roasting I in an oxygen-containing atmosphere to obtain an intermediate with an alumina coating;
(3) Immersing the intermediate with the alumina coating in a precursor solution containing a first element and a second element in an equal volume, drying II, and roasting II in a reducing atmosphere to obtain the catalyst;
Wherein the first element is selected from at least five of Mg, al, ce, la, sr, W, K, zr, mn, ba, si, nb, mo, nd, gd;
The second element is selected from at least one of Ni, co, ru, rh, ir, pt.
4. The preparation method according to claim 3, wherein the mass ratio of gamma-Al 2O3, pseudo-boehmite, al (OH) 3, polyvinyl alcohol, citric acid and water is 1:0.1 to 0.5:0.2 to 1.0:0.5 to 2.0:0.05 to 0.2:2.0 to 4.0.
5. The method according to claim 3, wherein the precursor solution containing the first element and the second element is selected from at least one of nitrate, hydrochloride, acetate containing the first element and the second element;
preferably, the honeycomb support is selected from ceramic honeycomb supports and/or metal honeycomb ceramics;
The honeycomb carrier is subjected to an acid treatment prior to use.
6. The method according to claim 3, wherein in the step (1), the rotational speed of the ball milling is 300-800 r/min, and the time of the ball milling is 2-10 hours;
Preferably, in the step (1), the average particle diameter of the slurry A is 1.0-4.0 μm;
preferably, in step (1), the pH of slurry A is 1.0 to 6.0.
7. A method according to claim 3, wherein in step (2), the time of the impregnation is 1 to 3 minutes;
Preferably, in the step (2), the temperature of the drying I is 100-150 ℃, and the time of the drying I is 2-10 h;
Preferably, in the step (2), the temperature of the roasting I is 600-900 ℃, and the time of the roasting I is 2-6 h.
8. The method according to claim 3, wherein in the step (3), the temperature of the drying II is 100-150 ℃, and the time of the drying II is 2-10 hours;
preferably, in the step (3), the time of roasting II is 700-1100 ℃, and the time of roasting II is 2-8 h.
9. A method of preparation according to claim 3, wherein the solid to liquid ratio of the honeycomb carrier to slurry a is 1:1 to 3.
10. Use of a catalyst according to claim 1 or 2 or obtainable by a process according to any one of claims 3 to 9 in a reaction for the reforming of methane and CO 2 to produce synthesis gas.
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