An efficient porous visible-light photocatalytic H2S splitting hydrogen production catalyst and its preparation method

Abstract

Provided is a highly efficient porous visible-light photocatalytic H2S decomposition hydrogen production catalyst and a preparation method thereof. The catalyst is a porous metal sulfide@perovskite oxide heterojunction catalyst; wherein, the metal sulfide is loaded on the porous perovskite oxide. The preparation method forms a perovskite oxide on a SiO2 template, then removes the template to obtain a porous perovskite oxide, and then loads the metal sulfide on the porous perovskite oxide, finally obtaining a porous metal sulfide@perovskite oxide heterojunction catalyst, which effectively increases the contact area between the catalyst and light, and thus significantly improves the photocatalytic reaction efficiency of the heterojunction catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst material preparation, and particularly relates to a highly efficient porous visible-light catalytic H2S decomposition hydrogen production catalyst and a preparation method thereof. Background Art

[0002] A large amount of H2S is generated in the production processes of petrochemical and coal chemical industries. H2S is a chemical that is extremely harmful to the environment and human health. The main method for treating H2S in industry is the Claus process, which has a series of problems such as high energy consumption in this process, secondary pollution caused by harmful substances generated, and waste of hydrogen resources due to the formation of water from hydrogen atoms.

[0003] By using photocatalytic technology to decompose H2S, the hydrogen in H2S can be recovered to achieve resource utilization, and solar energy resources can be utilized to collect and store solar energy in the form of fuel hydrogen, achieving the win-win goal of reducing energy consumption and not polluting the environment, which has obvious advantages compared with other H2S treatment methods.

[0004] When two semiconductor materials with different band gaps are combined to form a heterojunction, the advantages of the two semiconductors can be complementary, which is an important way to expand the spectral response range of the catalyst, improve the separation efficiency of electrons and holes, and effectively improve the photocatalytic reaction performance.

[0005] Metal sulfides have a relatively narrow band gap and good light absorption properties, and are the most commonly used catalysts for photocatalytic decomposition of H2S at present, especially outstanding in the performance of decomposing H2S under visible light conditions.

[0006] ABO3 perovskite metal oxides are a class of semiconductor materials with excellent properties and wide applications, and are considered to be one of the most promising photocatalysts, which are widely used in multiple photocatalytic fields. For example, Chinese Patent Application CN111346644A uses perovskite as a photocatalyst, and shows good results in photocatalytic water splitting for hydrogen production.

[0007] It can be expected that if a heterostructure is formed by combining metal sulfide and perovskite, the efficiency of photocatalytic decomposition of H2S can be greatly improved. However, overall, the specific surface area of the heterojunction photocatalyst prepared by the traditional preparation method is small, and the catalytic efficiency is low.

[0008] To solve this technical problem, in the prior art, a traditional carrier is used to load the photocatalyst, but this will reduce the light absorption efficiency of the catalyst, and the improvement of the catalytic efficiency of the entire catalytic system is not obvious.

[0009] Therefore, a new visible-light catalytic H2S decomposition hydrogen production catalyst and a preparation method thereof are needed to solve the above technical problems. Summary of the Invention

[0010] To this end, in view of the deficiencies of the prior art, the present invention provides a highly efficient porous visible-light catalytic H2S decomposition hydrogen production catalyst, and the catalyst is a porous metal sulfide@perovskite oxide heterojunction catalyst; wherein, the metal sulfide is loaded on the porous perovskite oxide.

[0011] Among them, the content of the metal sulfide is 5-60% by mass; the content of the perovskite oxide is 40-95% by mass.

[0012] Among them, the metal sulfide is one selected from MnS, CuS, In2S3, CdS, Bi2S3; the perovskite oxide is one selected from SrTiO3, BaTiO3, NiTiO3, CoTiO3, FeTiO3, NaTaO3, AgTaO3, KTaO3, AgNbO3, CuNbO3, LaFeO3, BiFeO3.

[0013] The present invention also provides a preparation method of the above-mentioned highly efficient porous visible-light catalytic H2S decomposition hydrogen production catalyst, including the steps:

[0014] (1) Take a certain amount of metal precursor and drop it into an aqueous citric acid solution to obtain solution M1;

[0015] (2) After stirring solution M1 for a certain time, drop a certain amount of aqueous metal nitrate solution into solution M1 to obtain solution M2;

[0016] (3) Add a certain amount of porous SiO2 support to solution M2 to form a suspension;

[0017] (4) After stirring the suspension for a certain time, heat it to a certain temperature, and while stirring, carry out drying to obtain a first solid;

[0018] (5) Dry the first solid and then calcine it to obtain a supported perovskite oxide;

[0019] (6) Add the supported perovskite oxide to an aqueous NaOH solution with a certain concentration, stir for a certain time, and then pour it into a hydrothermal reactor to react for a period of time to remove silica in the solid material to obtain a mixture;

[0020] (7) Carry out suction filtration and washing on the mixture until the pH value is neutral, and then dry the washed solid to obtain a porous perovskite oxide;

[0021] (8) Pour a certain amount of porous perovskite oxide, a certain amount of metal nitrate, thioacetamide and pyridine solution into a high-pressure reactor, and keep the temperature constant and react for a certain time;

[0022] (9) After the reaction is completed, cool down, filter, wash, and dry the obtained solid to obtain the porous catalyst.

[0023] Among them, in the step (1), the metal precursor is one selected from tetrabutyl titanate, orthothallate, niobium oxalate, and iron nitrate.

[0024] Among them, in the step (2) or (4), the stirring time is 30 min.

[0025] Among them, in the step (2), the metal nitrate is one selected from strontium nitrate, barium nitrate, nickel nitrate, iron nitrate, sodium nitrate, silver nitrate, potassium nitrate, copper nitrate, lanthanum nitrate, and bismuth nitrate.

[0026] Among them, in the step (3), the porous SiO2 support is one selected from SBA-15, MCM-41, synthetic zeolite, and silica gel.

[0027] Among them, in the step (4), the temperature is raised to 60 - 80 °C.

[0028] Among them, in the step (5), the first solid is dried overnight.

[0029] Among them, in the step (5), the drying temperature is 60 - 120 °C, and the calcination temperature is 500 - 1000 °C.

[0030] Among them, in the step (6), the concentration of the NaOH aqueous solution is 1 - 3 mol / L.

[0031] Among them, in the step (6), the stirring is carried out at room temperature, and the stirring time is 8 h.

[0032] Among them, in the step (6), the reaction temperature in the hydrothermal autoclave is 80 - 150 °C, and the reaction time is 8 - 24 h.

[0033] Among them, in the step (7), deionized water or ethanol is used for suction filtration and washing.

[0034] Among them, in the step (7), the washing is carried out until the pH = 7.

[0035] Among them, in the step (7), the drying temperature is 80 °C.

[0036] Among them, in the step (8), the metal nitrate is one selected from manganese nitrate, copper nitrate, indium nitrate, cadmium nitrate, and bismuth nitrate.

[0037] Among them, in the step (8), the inner liner of the high-pressure reaction kettle is made of polytetrafluoroethylene.

[0038] Among them, in the step (8), the reaction temperature is 180 °C and the reaction time is 18 - 36 h.

[0039] Among them, in the step (9), the cooling is natural cooling to room temperature; ethanol is used to filter and wash the obtained solid; the drying temperature is 50 - 100 °C.

[0040] The present invention also provides the use of the catalyst, and the catalyst is used for catalytically decomposing H2S to produce hydrogen under visible light conditions.

[0041] The present invention has the following beneficial technical effects:

[0042] (1) The present invention uses a composite of metal sulfide and perovskite oxide to form a heterojunction catalyst, and the heterojunction catalyst can be used to decompose H2S under visible light conditions, which can effectively avoid the problems of high energy consumption and still polluted tail gas in the traditional H2S treatment process; at the same time, H2S can also be decomposed into H2 and sulfur to realize the efficient utilization of H2S.

[0043] (2) The efficiency of the traditional catalytic decomposition of H2S process under visible light conditions is relatively low, while the present invention synthesizes a metal sulfide@perovskite oxide heterojunction catalyst by combining metal sulfide and perovskite materials, making full use of the characteristics of strong light absorption performance of metal sulfide and high response degree of perovskite oxide under visible light conditions to realize the combination of the advantages of the two catalysts. At the same time, the prepared catalyst is a porous catalyst, which further improves the light efficiency, so that H2S can be efficiently decomposed into H2 and elemental S under visible light conditions. While efficiently treating H2S pollutants, clean energy H2 can be obtained to realize the efficient and clean utilization of H2S, and the energy consumption during the treatment process is extremely low.

[0044] (3) The specific surface area of the traditionally generated heterojunction catalyst is relatively small and the photocatalytic efficiency is weak. In the prior art, traditional carriers are used for loading, but this will weaken the photocatalytic efficiency of the catalyst. The porous heterojunction photocatalyst prepared by the present invention forms perovskite oxide on the SiO2 template, then removes the template to obtain porous perovskite oxide, and then loads metal sulfide on the porous perovskite oxide to finally obtain a metal sulfide@perovskite oxide porous heterojunction catalyst, which effectively increases the contact area between the catalyst and light, and further significantly improves the photocatalytic reaction efficiency of the heterojunction catalyst. Specific Embodiments

[0045] In order to make the purpose, technical solution and advantages of the present invention clearer, the following further elaborates on the present invention in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Example 1

[0047] 7.4 g of tetrabutyl titanate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 4.61 g of an aqueous strontium nitrate solution was dropped into the aqueous solution of M1 to obtain solution M2. After adding 2.6 g of SBA-15 and stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution was gradually dried into a solid. The obtained solid was dried at 120 °C and calcined at 750 °C to prepare a supported SrTiO3 perovskite oxide. A certain amount of the supported SrTiO3 perovskite oxide was poured into a 3 mol / L aqueous NaOH solution and stirred at room temperature for 8 h. Then the solution was poured into a hydrothermal reactor and reacted at 80 °C for 24 h to remove SiO2 in the solid material. For the hydrothermally treated mixture, it was filtered and washed with deionized water until the pH = 7. Then the washed solid was dried at 80 °C to obtain a porous perovskite oxide SrTiO3. The porous perovskite oxide SrTiO3, 2.05 g of manganese nitrate, thioacetamide and a pyridine solution were jointly poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 18 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing was completed, it was dried at 60 °C to obtain 5.0 g of a porous MnS@SrTiO3 heterojunction catalyst with a MnS content of 20%.

[0048] Example 2

[0049] 5.1 g of tetrabutyl titanate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 3.92 g of an aqueous barium nitrate solution was dropped into the aqueous solution of M1 to obtain solution M2. A certain amount of 6.0 g of MCM-41 was added thereto. After stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution was gradually dried into a solid. Then, the obtained solid was dried at 100 °C and calcined at 850 °C to prepare a supported BaTiO3 perovskite oxide. The prepared supported BaTiO3 perovskite oxide was poured into a 3 mol / L aqueous NaOH solution and stirred at room temperature for 8 h. Then, the solution was poured into a hydrothermal reactor and reacted at 80 °C for 24 h to remove SiO2 in the solid material. For the hydrothermally treated mixture, ethanol was used for suction filtration and washing until pH = 7. Then, the washed solid was dried at 80 °C to obtain a porous perovskite oxide BaTiO3. The porous perovskite oxide BaTiO3, 2.94 g of copper nitrate, and a certain amount of thioacetamide and pyridine solution were jointly poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 24 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing was completed, it was dried at 80 °C to obtain 5.0 g of a porous CuS@BaTiO3 heterojunction catalyst with a CuS content of 30%.

[0050] Example 3

[0051] 5.0 g of tetrabutyl titanate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 2.5 g of an aqueous silver nitrate solution was dropped into the aqueous solution of M1 to obtain solution M2. A certain amount of silica gel was added to M2. After stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution was gradually dried to form a solid. Then, the obtained solid was dried at 80 °C and calcined at 950 °C to prepare a supported AgTiO3 perovskite oxide. A certain amount of the supported AgTiO3 perovskite oxide was poured into a 2 mol / L aqueous NaOH solution and stirred at room temperature for 8 h. Then, the solution was poured into a hydrothermal reactor and reacted at 100 °C for 24 h to remove SiO2 in the solid material. For the hydrothermally treated mixture, deionized water was used for suction filtration and washing until pH = 7. Then, the washed solid was dried at 80 °C to obtain a porous perovskite oxide AgTiO3. A certain amount of the porous perovskite oxide AgTiO3, 3.7 g of indium nitrate, and a certain amount of thioacetamide and pyridine solution were jointly poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 30 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing was completed, it was dried at 60 °C to obtain 5 g of a porous In2S3@TiO3 heterojunction catalyst with an In2S3 content of 40%.

[0052] Example 4

[0053] 4.39 g of niobium oxalate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 1.7 g of an aqueous silver nitrate solution was dropped into the aqueous solution of M1 to obtain solution M2. After stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution gradually dried to form a gel. Then the gel was dried at 110 °C and calcined at 650 °C to obtain a supported AgNbO3 perovskite oxide. A certain amount of the supported AgNbO3 perovskite oxide was poured into a 2 mol / L aqueous NaOH solution and stirred at room temperature for 16 h. Then the solution was poured into a hydrothermal reactor and reacted at 120 °C for 24 h to remove SiO2 in the solid material. For the hydrothermally treated mixture, it was filtered and washed with deionized water until pH = 7. Then the washed solid was dried at 80 °C to obtain a porous perovskite oxide AgNbO3. A certain amount of the porous perovskite oxide AgNbO3, 3.84 g of bismuth nitrate, thioacetamide and pyridine solution were jointly poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 36 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing ended, it was dried at 70 °C to obtain a porous Bi2S3@AgNbO3 heterojunction catalyst with a Bi2S3 content of 50%.

[0054] Comparative Example 1 - The prepared catalyst was a supported SrTiO3 perovskite oxide

[0055] 7.4 g of tetrabutyl titanate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 4.61 g of an aqueous strontium nitrate solution was dropped into the aqueous solution of M1 to obtain solution M2. After adding 2.6 g of SBA-15 and stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution gradually dried to become a solid. The obtained solid was dried at 120 °C and calcined at 750 °C to obtain a supported SrTiO3 perovskite oxide.

[0056] Comparative Example 2 - The prepared catalyst was MnS

[0057] 2.05 g of manganese nitrate, thioacetamide and pyridine solution were jointly poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 18 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing ended, it was dried at 60 °C to obtain MnS.

[0058] Comparative Example 3 - The prepared catalyst was a supported MnS@SrTiO3 heterojunction catalyst

[0059] 7.4 g of tetrabutyl titanate was dropped into an aqueous citric acid solution to obtain solution M1. After stirring for 30 min, 4.61 g of an aqueous strontium nitrate solution was dropped into the M1 aqueous solution to obtain solution M2. After adding 2.6 g of SBA-15 and stirring for 30 min, the temperature was raised to 80 °C. Under strong stirring, the solution gradually dried to become a solid. The obtained solid was dried at 120 °C and calcined at 750 °C to prepare a supported SrTiO3 perovskite oxide. A certain amount of the supported SrTiO3 perovskite oxide, 2.05 g of manganese nitrate, thioacetamide and a pyridine solution were poured into a high-pressure reactor with a polytetrafluoroethylene inner liner and kept at 180 °C for 18 h. After the reaction ended, it was naturally cooled to room temperature. The obtained solid sample was filtered and washed with ethanol. After the washing ended, it was dried at 60 °C to obtain a supported MnS@SrTiO3 heterojunction catalyst.

[0060] Catalyst evaluation process

[0061] H2S gas was continuously introduced into the reactor of the photocatalytic evaluation device equipped with a specific organic solvent and a photocatalyst. The amount of the catalyst added was 50 mg, the gas flow rate was 10 ml / min. After evacuating the system, it was irradiated with a xenon lamp. The light source intensity was 300 W. A certain reaction temperature was controlled, and the generated hydrogen was detected online by gas chromatography.

[0062] The obtained test results are shown in Table 1.

[0063] Table 1 Catalyst evaluation results of examples and comparative examples

[0064] Catalyst Hydrogen production activity (mmol / h) Example 1 35 Example 2 32 Example 3 34 Example 4 36 Comparative Example 1 10 Comparative Example 2 5 Comparative Example 3 18

[0065] Obviously, the above examples are only for clearly illustrating the examples and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A preparation method of a porous catalyst, wherein the catalyst is a porous metal sulfide@perovskite oxide heterojunction catalyst; Wherein, The metal sulfide is supported on a porous perovskite oxide; wherein, the content of the metal sulfide is 20-60% by mass; the content of the perovskite oxide is 40-80% by mass; Among them, the preparation method of the porous catalyst includes the steps: (1) Take a certain amount of metal precursor and drop it into an aqueous citric acid solution to obtain solution M1; (2) After stirring solution M1 for a certain time, drop a certain amount of aqueous metal nitrate solution into solution M1 to obtain solution M2; (3) Add a certain amount of porous SiO2 support to solution M2 to form a suspension; (4) After stirring the suspension for a certain time, heat it up to a certain temperature, and then stir to dry to obtain a first solid; (5) Dry the first solid and then calcine it to obtain a supported perovskite oxide; (6) Add the supported perovskite oxide to an aqueous NaOH solution with a certain concentration, stir for a certain time, and then pour it into a hydrothermal reactor to react for a period of time to remove silica in the solid material to obtain a mixture; (7) Filter and wash the mixture until the pH value is neutral, and then dry the washed solid to obtain a porous perovskite oxide; (8) Pour a certain amount of porous perovskite oxide, a certain amount of metal nitrate, thioacetamide and pyridine solution into a high-pressure reactor, and keep the temperature for a certain reaction time; (9) After the reaction is completed, cool it, filter, wash and dry the obtained solid to obtain the porous catalyst; Among them, in step (1), the metal precursor is one selected from tetrabutyl titanate, niobium oxalate, and iron nitrate; Among them, in step (2), the metal nitrate is one selected from strontium nitrate, barium nitrate, nickel nitrate, iron nitrate, sodium nitrate, silver nitrate, potassium nitrate, copper nitrate, lanthanum nitrate, and bismuth nitrate; Among them, in step (8), the metal nitrate is one selected from manganese nitrate, copper nitrate, indium nitrate, cadmium nitrate, and bismuth nitrate.

2. The preparation method of the porous catalyst according to claim 1, wherein, The metal sulfide is one selected from MnS, CuS, In2S3, CdS, and Bi2S3; the perovskite oxide is one selected from SrTiO3, BaTiO3, NiTiO3, CoTiO3, FeTiO3, AgNbO3, CuNbO3, LaFeO3, and BiFeO3.

3. The preparation method of the porous catalyst according to claim 1, wherein, In step (6), the concentration of the NaOH aqueous solution is 1-3 mol / L.

4. The preparation method of the porous catalyst according to claim 1, wherein, In step (3), the porous SiO2 support is one selected from SBA-15, MCM-41, synthetic zeolite, and silica gel.

5. The preparation method of the porous catalyst according to claim 1, wherein, In step (4), the heating up is to heat up to 60-80 °C.

6. The preparation method of the porous catalyst according to claim 1, wherein, In step (5), the drying temperature is 60-120 °C, and the calcination temperature is 500-1000 °C.

7. The preparation method of the porous catalyst according to claim 1, wherein, In step (6), the reaction temperature in the hydrothermal reactor is 80-150 °C, and the reaction time is 8-24 h.

8. The preparation method of the porous catalyst according to claim 1, wherein, In step (8), the reaction temperature is 180 °C, and the reaction time is 18-36 h.

9. A porous catalyst prepared by the preparation method of the porous catalyst according to any one of claims 1-8.

10. The use of the porous catalyst according to claim 9, wherein the porous catalyst is used for catalytic decomposition of H2S to produce hydrogen under visible light conditions.