CN118253326A - Potassium modified cobalt molybdenum nitride catalyst and preparation method and application thereof - Google Patents
Potassium modified cobalt molybdenum nitride catalyst and preparation method and application thereof Download PDFInfo
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- CN118253326A CN118253326A CN202410329850.XA CN202410329850A CN118253326A CN 118253326 A CN118253326 A CN 118253326A CN 202410329850 A CN202410329850 A CN 202410329850A CN 118253326 A CN118253326 A CN 118253326A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 132
- 229910052700 potassium Inorganic materials 0.000 title claims abstract description 58
- 239000011591 potassium Substances 0.000 title claims abstract description 58
- -1 Potassium modified cobalt molybdenum Chemical class 0.000 title claims abstract description 32
- 238000002360 preparation method Methods 0.000 title abstract description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 219
- 238000006243 chemical reaction Methods 0.000 claims abstract description 138
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 78
- 238000000354 decomposition reaction Methods 0.000 claims abstract description 47
- 239000002243 precursor Substances 0.000 claims abstract description 35
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000001257 hydrogen Substances 0.000 claims abstract description 27
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 27
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000011609 ammonium molybdate Substances 0.000 claims abstract description 19
- 235000018660 ammonium molybdate Nutrition 0.000 claims abstract description 19
- 229940010552 ammonium molybdate Drugs 0.000 claims abstract description 19
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 15
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 claims abstract description 9
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims abstract description 6
- 239000010453 quartz Substances 0.000 claims description 78
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 78
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 60
- 239000002245 particle Substances 0.000 claims description 51
- 238000001035 drying Methods 0.000 claims description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 48
- 238000010438 heat treatment Methods 0.000 claims description 40
- 238000007789 sealing Methods 0.000 claims description 38
- 238000005406 washing Methods 0.000 claims description 37
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 30
- 239000000843 powder Substances 0.000 claims description 29
- 239000012774 insulation material Substances 0.000 claims description 26
- 238000000227 grinding Methods 0.000 claims description 25
- 238000004519 manufacturing process Methods 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 14
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 13
- 238000001914 filtration Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 9
- 238000001354 calcination Methods 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 2
- AFTDTIZUABOECB-UHFFFAOYSA-N [Co].[Mo] Chemical class [Co].[Mo] AFTDTIZUABOECB-UHFFFAOYSA-N 0.000 claims 5
- 229910000510 noble metal Inorganic materials 0.000 abstract description 7
- WHDPTDWLEKQKKX-UHFFFAOYSA-N cobalt molybdenum Chemical compound [Co].[Co].[Mo] WHDPTDWLEKQKKX-UHFFFAOYSA-N 0.000 abstract description 4
- 150000004767 nitrides Chemical class 0.000 abstract description 4
- 238000002715 modification method Methods 0.000 abstract 1
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 63
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 38
- 239000008367 deionised water Substances 0.000 description 35
- 229910021641 deionized water Inorganic materials 0.000 description 35
- 229910052724 xenon Inorganic materials 0.000 description 34
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 34
- 238000012216 screening Methods 0.000 description 24
- 239000007787 solid Substances 0.000 description 23
- 229910002512 Co3Mo3N Inorganic materials 0.000 description 19
- 229910052750 molybdenum Inorganic materials 0.000 description 13
- 239000011733 molybdenum Substances 0.000 description 13
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 12
- QGUAJWGNOXCYJF-UHFFFAOYSA-N cobalt dinitrate hexahydrate Chemical compound O.O.O.O.O.O.[Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QGUAJWGNOXCYJF-UHFFFAOYSA-N 0.000 description 12
- 230000000694 effects Effects 0.000 description 12
- 238000005121 nitriding Methods 0.000 description 12
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 12
- 239000002244 precipitate Substances 0.000 description 12
- 238000004088 simulation Methods 0.000 description 12
- 235000010333 potassium nitrate Nutrition 0.000 description 11
- 230000004048 modification Effects 0.000 description 10
- 238000012986 modification Methods 0.000 description 10
- 239000004323 potassium nitrate Substances 0.000 description 9
- 230000003197 catalytic effect Effects 0.000 description 6
- 229910052783 alkali metal Inorganic materials 0.000 description 5
- 150000001340 alkali metals Chemical class 0.000 description 5
- 229910052723 transition metal Inorganic materials 0.000 description 5
- 150000003624 transition metals Chemical class 0.000 description 5
- 230000001737 promoting effect Effects 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229910052707 ruthenium Inorganic materials 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 229910015667 MoO4 Inorganic materials 0.000 description 1
- 238000005915 ammonolysis reaction Methods 0.000 description 1
- 239000012018 catalyst precursor Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 150000003112 potassium compounds Chemical class 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/24—Nitrogen compounds
-
- 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
- C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
- C01B3/047—Decomposition of ammonia
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Combustion & Propulsion (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
Abstract
The invention discloses a potassium modified cobalt molybdenum nitride catalyst and a preparation method and application thereof. The invention provides a cobalt-molybdenum bimetallic nitride ammonia decomposition catalyst, which is characterized in that a precursor is obtained by mixing and reacting a cobalt nitrate solution and an ammonium molybdate solution, and the precursor is stirred and dried with a potassium carbonate solution and then calcined in an ammonia environment to obtain a potassium modified cobalt-molybdenum nitride catalyst. According to the invention, the non-noble metal catalyst is prepared by a potassium modification method, can efficiently catalyze and promote solar ammonia decomposition to prepare hydrogen under the low-temperature condition, can achieve more than 87% of ammonia decomposition conversion rate under the reaction condition of 500 ℃ and 0.1MPa, can efficiently catalyze ammonia decomposition to prepare hydrogen under the low-temperature condition, and has great industrial application significance.
Description
Technical Field
The invention belongs to the technical field of catalyst preparation, and particularly relates to a potassium modified cobalt molybdenum nitride catalyst, and a preparation method and application thereof.
Background
The hydrogen energy is used as clean energy with high energy density, plays an important role in solving the problems of energy crisis, global warming, environmental pollution and the like, and severe storage and transportation conditions seriously affect the application of the hydrogen energy. Ammonia (NH 3) is considered a very promising renewable hydrogen (H 2) carrier due to its high hydrogen content and convenient transportation and storage conditions. Solar ammonia decomposition provides a green sustainable pathway for hydrogen release from ammonia, but traditional solar ammonia decomposition typically requires operating temperatures >550 ℃ and expensive and complex concentrating equipment, so developing a catalyst that efficiently promotes ammonia decomposition at low temperatures is critical for large-scale applications of solar ammonia decomposition hydrogen production.
Ruthenium-based catalysts are currently considered to be the most active ammonia decomposition catalysts at low temperatures, and generally achieve higher ammonia decomposition conversion rates at 500 ℃, however the scarcity and high cost of ruthenium have prevented commercial scale applications; ni, co, mo, fe and other non-noble metal transition metals are considered to be capable of replacing ruthenium-based catalysts, wherein the nickel-based catalysts have the highest activity, but have the problems of easy sintering, poor stability and the like, and are difficult to meet the solar ammonia decomposition under the low-temperature condition.
Currently, non-noble metal double transition metal catalysts are a research hotspot, and the synergistic effect of double transition metals can show excellent ammonia decomposition activity, but they still do not perform well under low temperature conditions. Meanwhile, research proves that alkali metal modification can effectively promote the catalytic activity of the ammonia decomposition catalyst, but the interaction of different alkali metals and the catalyst still needs further research.
In summary, the synergistic effect of double transition metals is explored, the optimal double transition metal catalyst is screened out, and the alkali metal modification with proper proportion is utilized, so that the improvement of the low-temperature ammonia decomposition activity is a new idea for constructing a novel solar ammonia decomposition catalyst.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a potassium modified cobalt molybdenum nitride catalyst, a preparation method thereof and application thereof in catalytic ammonia decomposition hydrogen production reaction. The cobalt-molybdenum bimetallic nitride ammonia decomposition catalyst provided by the invention has excellent performance, and based on the alkali metal modification principle, the K x-Co3Mo3 N non-noble metal nitride catalyst is prepared, so that the ammonia decomposition activity of the catalyst is further improved, and the catalyst can efficiently catalyze ammonia to decompose and prepare hydrogen under the low-temperature condition.
The invention provides a preparation method of a potassium modified cobalt molybdenum nitride catalyst, which specifically comprises the following steps:
1) Mixing a cobalt nitrate solution and an ammonium molybdate solution, performing constant-temperature reaction for 12 hours at 80 ℃, cooling to room temperature after the reaction is finished, filtering, washing filter residues with water, drying and grinding to obtain precursor CoMoO 4 powder;
2) Adding a potassium carbonate solution into the precursor CoMoO 4 powder in the step 1), stirring, drying at 80 ℃ completely, and calcining in an ammonia environment to obtain the potassium modified cobalt molybdenum nitride catalyst K x-Co3Mo3 N.
Further, the invention also defines that the concentration of the cobalt nitrate (Co (NO 3)2·6H2 O, relative molecular weight 291) solution is 0.4mol/L, the concentration of ammonium molybdate ((NH 4)2MoO4, relative molecular weight 196) is 0.4mol/L, the concentration of the potassium carbonate (K 2CO3, relative molecular weight 138) solution is 0.00116-0.116mol/L, and the feeding mole ratio of Co to Mo element is 1:1.
Further, the invention also defines that the precursor CoMoO 4 powder is selected by a filter screen to have a particle size of less than 40 microns.
Further, the invention also defines the calculation formula of the potassium carbonate feeding mass calculated by the mole number of Mo in the step 2) as follows:
Wherein, from the precursor to the catalyst, the mole number of Mo is unchanged, and in the catalyst, the proportion of potassium and molybdenum elements is x:3, calculating the mole number of potassium according to the mole number of Mo, wherein the mole number of potassium carbonate is half of that of potassium element, and then calculating the mass of potassium carbonate.
Further, the invention also defines that the molar ratio of potassium ions in the potassium carbonate to molybdenum ions in the ammonium molybdate in the potassium modified cobalt molybdenum nitride catalyst K x-Co3Mo3 N in step 2) is 0.005 to 0.5:1, preferably 0.01-0.1:1, most preferably 0.05:1; i.e. x=0.015-1.5, preferably 0.03-0.3, most preferably 0.15.
Further, the invention also defines that the calcining temperature in the step 2) is gradually increased from room temperature to 785 ℃, the total calcining time is 12 hours, and the gradual heating is specifically as follows: the precursor was fully aminated by heating from room temperature to 357 deg.c at 5 deg.c/min, then to 450 deg.c at 0.5 deg.c/min, and finally to 785 deg.c at 2.1 deg.c/min.
Further, the invention also defines a potassium modified cobalt molybdenum nitride catalyst obtained by the preparation method, which has the structural formula of K x-Co3Mo3 N, wherein x represents the molar ratio of potassium in a metal element in the catalyst, and x=0.015-1.5.
Furthermore, the invention also defines the application of the prepared potassium modified cobalt molybdenum nitride catalyst in the solar ammonia decomposition hydrogen production reaction; adding a potassium modified cobalt molybdenum nitride catalyst into a quartz reaction tube, wrapping the quartz reaction tube with a heat insulation material, placing the quartz reaction tube under a sunlight simulator, and introducing ammonia gas under a sealing condition for reaction, wherein the reaction temperature is 350-500 ℃, and the ammonia gas pressure is 0.1MPa.
By adopting the technical scheme, compared with the prior art, the invention has the following advantages:
1) The cobalt-molybdenum bimetallic nitride ammonia decomposition catalyst designed by the invention is based on an alkali metal modification principle, and a K x-Co3Mo3 N non-noble metal catalyst is prepared by a potassium modification mode, so that the catalyst can efficiently catalyze and promote solar ammonia decomposition to prepare hydrogen under a low-temperature condition, a catalyst precursor is formed by non-noble metal salt ammonium molybdate and cobalt nitrate, the precursor is mixed with potassium carbonate and then calcined to form a potassium modified cobalt-molybdenum nitride catalyst, the catalyst has high catalytic activity, ammonia decomposition can be carried out under the reaction condition of 350 ℃ and 0.1MPa, and the ammonia decomposition conversion rate can reach 100% under the reaction condition of 550 ℃ and 0.1 MPa; compared with other non-noble metal catalysts reported in the prior literature, the catalyst generally needs more than 800 ℃ of reaction conditions to achieve similar catalytic effects, can efficiently catalyze ammonia to decompose and produce hydrogen at low temperature, and has great industrial application significance;
2) The invention adopts sectional heating during calcination, which can make the ammoniation reaction more sufficient;
3) According to the invention, the effect of improving the ammonia decomposition activity of Co 3Mo3 N by experimental comparison of different potassium compound accelerators (K 2CO3、KOH、KNO3) is found that the promoting effect of K 2CO3 is obviously better than that of KOH and KNO 3, so that the preparation process of the invention adopts K 2CO3 as the accelerator to better meet the requirements of economy, environmental protection and practicability.
Drawings
FIG. 1 is a graph showing the ammonia decomposition conversion of the catalysts of examples 1 to 4,5 to 8, 9 to 12, 13 to 16, 17 to 20, 21 to 24 of the present invention;
FIG. 2 (a) is a graph showing the ammonia decomposition conversion rate of the catalysts of examples 1 to 4, 9 to 12, 25 to 28, and 33 to 36 according to the present invention;
FIG. 2 (b) is a graph showing the ammonia decomposition conversion rate of the catalysts of examples 1 to 4, 13 to 16, 29 to 32, 41 to 44 according to the present invention;
FIG. 2 (c) is a graph showing the ammonia decomposition conversion rate of the catalysts of examples 1 to 4, 17 to 20, 33 to 36, 45 to 48 according to the present invention;
FIG. 3 shows XRD patterns of catalysts of examples 1 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20, and 21 to 24 of the present invention;
FIG. 4 is an XPS plot of catalysts of examples 13-16 of the present invention;
FIG. 5 is an SEM image of the catalysts of examples 13-16 of the invention.
Detailed Description
The following examples are given to illustrate the present invention, but the present invention is not limited thereto:
The equipment, reagents, processes, parameters, etc. according to the present invention are conventional equipment, reagents, processes, parameters, etc. unless otherwise specified, and are not exemplified. All ranges recited herein are inclusive of all point values within the range. The terms "about," "about," or "about" and the like as used herein refer to a range of + -20% of the stated range or value.
In the present invention, the "room temperature" is a conventional ambient temperature, and may be 10 to 30 ℃.
Examples 1 to 4
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen. Nitriding at high temperature in pure ammonia atmosphere, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain cobalt-molybdenum nitride catalyst, screening particles with particle size smaller than 20 microns by a filter screen, and marking the catalyst as Co 3Mo3 N.
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g of Co 3Mo3 N catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube respectively reaches 350 ℃, 400 ℃, 450 ℃,500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 1-4 of table 1.
Examples 5 to 8
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium carbonate is calculated by the following formula:
Dissolving 0.0032g of potassium carbonate in 20ml of deionized water, adding 2g of precursor powder into the potassium carbonate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in a pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in an ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.005. The catalyst is marked as K 0.015-Co3Mo3N(K2CO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.015-Co3Mo3N(K2CO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃, 500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 6-8 in table 1.
Examples 9 to 12
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium carbonate is calculated by the following formula:
Dissolving 0.0063g of potassium carbonate in 20ml of deionized water, adding 2g of precursor powder into the potassium carbonate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.01. The catalyst is marked as K 0.03-Co3Mo3N(K2CO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.03-Co3Mo3N(K2CO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a collecting lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃, 500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 9-12 of table 1.
Examples 13 to 16
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium carbonate is calculated by the following formula:
Dissolving 0.032g of potassium carbonate in 20ml of deionized water, adding 2g of precursor powder into the potassium carbonate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.05. The catalyst is marked as K 0.15-Co3Mo3N(K2CO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.15-Co3Mo3N(K2CO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a collecting lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃,500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 13-16 of table 1.
Examples 17 to 20
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium carbonate is calculated by the following formula:
Dissolving 0.063g of potassium carbonate in 20ml of deionized water, adding 2g of precursor powder into the potassium carbonate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.1. The catalyst is marked as K 0.3-Co3Mo3N(K2CO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.3-Co3Mo3N(K2CO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a collecting lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃,500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are shown in sequence numbers 17-20 of table 1.
Examples 21 to 24
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium carbonate is calculated by the following formula:
Dissolving 0.32g of potassium carbonate in 20ml of deionized water, adding 2g of precursor powder into the potassium carbonate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.5. The catalyst is marked as K 1.5-Co3Mo3N(K2CO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.3-Co3Mo3N(K2CO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃,500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 21-24 of table 1.
Examples 25 to 28
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of potassium hydroxide is calculated from the following formula:
Dissolving 0.0051g of potassium hydroxide in 20ml of deionized water, adding 2g of precursor powder into the potassium hydroxide solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.01. The catalyst was designated as K 0.03-Co3Mo3 N (KOH).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g of K 0.03-Co3Mo3 N (KOH) catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure the temperature in the quartz tube to be stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built up by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube respectively reaches 350 ℃,400 ℃,450 ℃ and 500 ℃ (measured by a temperature sensor) after the indication of an outlet flow controller is stable, data are recorded, and the ammonia gas conversion rate is calculated according to the formula of which is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) by 100%, and the results are listed in the sequence numbers 25-28 of table 1.
Examples 29 to 32
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of potassium hydroxide is calculated from the following formula:
Dissolving 0.026g of potassium hydroxide in 20ml of deionized water, adding 2g of precursor powder into the potassium hydroxide solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.05. The catalyst was designated as K 0.15-Co3Mo3 N (KOH).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g of K 0.15-Co3Mo3 N (KOH) catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure the temperature in the quartz tube to be stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built up by a collecting lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube respectively reaches 350 ℃,400 ℃,450 ℃ and 500 ℃ (measured by a temperature sensor) after the indication of an outlet flow controller is stable, data are recorded, and the ammonia gas conversion rate is calculated according to the formula of which is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) by 100%, and the results are listed in the sequence numbers 29-32 of table 1.
Examples 33 to 36
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of potassium hydroxide is calculated from the following formula:
Dissolving 0.051g of potassium hydroxide in 20ml of deionized water, adding 2g of precursor powder into the potassium hydroxide solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.1. The catalyst was designated as K 0.3-Co3Mo3 N (KOH).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g of K 0.3-Co3Mo3 N (KOH) catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure the temperature in the quartz reaction tube to be stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built up by a collecting lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃,400 ℃,450 ℃ and 500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of= (0.5 outlet flow rate/inlet flow rate) by 100%, and the results are listed in the sequence numbers 33-36 of table 1.
Examples 37 to 40
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium nitrate is calculated by the following formula:
Dissolving 0.0092g of potassium nitrate in 20ml of deionized water, adding 2g of precursor powder into the potassium nitrate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.01. The catalyst is marked as K 0.03-Co3Mo3N(KNO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.03-Co3Mo3N(KNO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃,500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 37-40 of table 1.
Examples 41 to 44
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium nitrate is calculated by the following formula:
Dissolving 0.046g of potassium nitrate in 20ml of deionized water, adding 2g of precursor powder into the potassium nitrate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.05. The catalyst is marked as K 0.15-Co3Mo3N(KNO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.15-Co3Mo3N(KNO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃, 500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are listed in sequence numbers 41-44 of table 1.
Examples 45 to 48
7.84G (0.04 mol) of ammonium molybdate, 11.64g (0.04 mol) of cobalt nitrate hexahydrate were each dissolved in 100ml of deionized water; mixing and stirring the two solutions, reacting at 80 ℃ for 12 hours, separating by a high-speed centrifuge to obtain a purple solid precipitate, washing with deionized water for three times, washing with absolute ethyl alcohol for one time, placing in a drying oven, drying at 80 ℃ for 10 hours, filtering, washing with water, drying, grinding to obtain precursor powder (CoMoO 4), and screening particles with the particle size smaller than 40 microns by a filter screen.
The mass of the potassium nitrate is calculated by the following formula:
Dissolving 0.092g of potassium nitrate in 20ml of deionized water, adding 2g of precursor powder into the potassium nitrate solution, drying at 80 ℃ to obtain a purple solid completely, nitriding at high temperature in pure ammonia atmosphere after grinding, heating to 357 ℃ from room temperature at 5 ℃/min, heating to 450 ℃ at 0.5 ℃/min, heating to 785 ℃ at 2.1 ℃/min, maintaining at the temperature for 5 hours, cooling to room temperature in ammonia atmosphere to obtain the potassium modified cobalt-molybdenum nitride catalyst, and screening particles with the particle size smaller than 20 microns by a filter screen, wherein the molar ratio of potassium to molybdenum is 0.01. The catalyst is marked as K 0.3-Co3Mo3N(KNO3).
Then, a solar ammonia decomposition hydrogen production simulation experiment is carried out, 0.3g K 0.3-Co3Mo3N(KNO3 of catalyst is added into a quartz reaction tube, the quartz reaction tube (except for a catalyst sealing section) is wrapped by a heat insulation material after sealing so as to ensure that the temperature in the quartz reaction tube is stable in the reaction process, then the wrapped quartz reaction tube is placed under a sunlight simulator (the sunlight simulator is built by a condenser lens and a xenon lamp), the xenon lamp is opened to irradiate the catalyst sealing section which is not wrapped by the heat insulation material, ammonia gas (space velocity GHSV=6000 ml NH3/gcat/h) is introduced into the quartz reaction tube at a flow rate of 30ml/min, the temperature in the quartz reaction tube is respectively up to 350 ℃, 400 ℃, 450 ℃, 500 ℃ (measured by a temperature sensor) by adjusting the power of the xenon lamp, data are recorded after the indication of an outlet flow controller is stable, and the ammonia gas conversion rate is calculated according to the formula of ammonia gas conversion rate= (0.5 outlet flow rate/inlet flow rate) 100%, and the results are shown in the sequence numbers 45-48 of table 1.
Table 1 ammonia decomposition conversion in each example
As can be seen from the data in Table 1, the proper amount of potassium modification improves the ammonia decomposition activity of Co 3Mo3 N catalyst, and the improvement effect of examples 9-12, 13-16 and 17-20 is obvious, wherein the catalyst of examples 13-16 (K 0.15-Co3Mo3N(K2CO3) has the best catalytic activity at low temperature. Meanwhile, as is clear from the data of comparative examples 1 to 4 and examples 21 to 24, the excessive potassium element modification inhibits the ammonolysis activity of the Co 3Mo3 N catalyst because the excessive potassium element exists on the catalyst surface and covers the active sites on the catalyst surface.
As can be seen from comparison of the example data in table 1, the potassium modification of the Co 3Mo3 N catalyst with KOH and KNO 3 also has a promoting effect, but under the same molar amount of potassium modification (K: mo=0.01, 0.1), the promoting effect of KOH and KNO 3 is less obvious than that of K 2CO3, so that K 2CO3 is an optimal Co 3Mo3 N potassium modifier compared with KOH and KNO 3 from the viewpoint of promoting effect and economy.
FIG. 1 is a graph showing the ammonia decomposition conversion rate of the catalysts of examples 1 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20 and 21 to 24 according to the present invention, and as can be seen from FIG. 1, the addition of a proper amount of potassium for modification significantly improves the ammonia decomposition activity of the Co 3Mo3 N catalyst, and the catalyst of examples 13 to 16 (K 0.15-Co3Mo3N(K2CO3) has a better catalytic activity at low temperatures.
As can be seen from the catalyst ammonia decomposition conversion maps in fig. 2 (a), 2 (b) and 2 (c), the molar ratio K: mo=0.01, 0.05, 0.1: under the condition of 1, K 2CO3, KNO3 and KOH have promotion effects on the Co 3Mo3 N catalyst at the temperature of 350-500 ℃, and the promotion effects of the K 2CO3, the KNO3 and the KOH are ordered as K 2CO3>KNO3 > KOH.
FIG. 3 shows XRD patterns of the catalysts of examples 1-4, 5-8, 9-12, 13-16, 17-20 and 21-24 of the invention, and it is clear from FIG. 3 that the diffraction patterns of all the K 2CO3 modified catalysts are consistent with the pure phase of Co 3Mo3 N, indicating that the XRD does not detect impurity phases, and that the potassium element is highly dispersed on the surface of Co 3Mo3 N.
FIG. 4 is an XPS plot of catalysts of examples 13-16 of the present invention; FIG. 5 is an SEM image of the catalysts of examples 13 to 16 of the present invention, and it is apparent from FIG. 4 that the potassium element was successfully incorporated into Co 3Mo3 N, and that the particle size of examples 13 to 16 (K 0.15-Co3Mo3N(K2CO3)) was about 10 μm, and that the potassium element was uniformly distributed on the surface of Co 3Mo3 N.
Claims (9)
1. A method for preparing a potassium modified cobalt molybdenum nitride catalyst, which is characterized by comprising the following steps:
1) Mixing a cobalt nitrate solution and an ammonium molybdate solution, performing constant-temperature reaction for 12 hours at 80 ℃, cooling to room temperature after the reaction is finished, filtering, washing filter residues with water, drying and grinding to obtain precursor CoMoO 4 powder;
2) Adding a potassium carbonate solution into the precursor CoMoO 4 powder in the step 1), stirring, drying at 80 ℃ completely, and calcining in an ammonia environment to obtain the potassium modified cobalt molybdenum nitride catalyst K x-Co3Mo3 N.
2. The method for preparing the potassium-modified cobalt-molybdenum nitride catalyst according to claim 1, wherein the concentration of the cobalt nitrate solution is 0.4mol/L, the concentration of the ammonium molybdate is 0.4mol/L, the concentration of the potassium carbonate solution is 0.00116-0.116mol/L, and the feeding mole ratio of Co to Mo element is 1:1.
3. The method for preparing the potassium modified cobalt molybdenum nitride catalyst according to claim 1, wherein the particle size of the precursor CoMoO 4 powder is less than 40 microns.
4. The method for preparing a potassium-modified cobalt molybdenum nitride catalyst according to claim 1, wherein in the step 2), the mass calculation formula of the potassium carbonate charge is as follows, calculated by mole number of Mo:
5. The method for preparing a potassium-modified cobalt molybdenum nitride catalyst according to claim 1, wherein the molar ratio of potassium element to molybdenum element in the potassium-modified cobalt molybdenum nitride catalyst K x-Co3Mo3 N in the step 2) is 0.005 to 0.5:1, preferably 0.01-0.1:1, most preferably 0.05:1; i.e. x=0.015-1.5, preferably 0.03-0.3, most preferably 0.15.
6. The method for preparing a potassium-modified cobalt molybdenum nitride catalyst according to claim 1, wherein the calcination temperature in step 2) is raised stepwise from room temperature to 785 ℃, the total calcination time is 12 hours, and the stepwise raising is specifically: the precursor was fully aminated by heating from room temperature to 357 deg.c at 5 deg.c/min, then to 450 deg.c at 0.5 deg.c/min, and finally to 785 deg.c at 2.1 deg.c/min.
7. A potassium modified cobalt molybdenum nitride catalyst having the structural formula K x-Co3Mo3 N, wherein x = 0.015-1.5, obtained according to the process of any one of claims 1-6.
8. Use of the potassium modified cobalt molybdenum nitride catalyst according to claim 7 in a solar ammonia decomposition hydrogen production reaction.
9. The use according to claim 8, characterized in that the solar ammonia decomposition hydrogen production reaction process is: adding a potassium modified cobalt molybdenum nitride catalyst into a quartz reaction tube, wrapping the quartz reaction tube with a heat insulation material, placing the quartz reaction tube under a sunlight simulator, and introducing ammonia gas under a sealing condition for reaction, wherein the reaction temperature is 350-500 ℃, and the ammonia gas pressure is 0.1MPa.
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