Catalyst for hydrogen deoxidation and purification as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for hydrogen deoxidation and purification as well as a preparation method and application thereof. The catalyst comprises SiC modified by hydrophobic functional groups as a carrier and an active component Pd loaded on the carrier, the catalyst adopts SiC as a carrier, has the advantages of good heat and electricity conductivity, high temperature resistance, acid and alkali corrosion resistance and the like, and can well disperse and stabilize an active component Pd loaded on the surface. The SiC surface has hydrogen overflow and oxygen overflow phenomena, and can be used as an active surface for hydrogen-oxygen reaction. The unique physicochemical property of SiC can prevent the overheating phenomenon in the catalytic deoxidation process, the reaction rate is effectively controlled, the metal utilization rate is improved, and the use cost is reduced. In addition, SiC is resistant to acid and alkali corrosion, so that after the catalyst is inactivated, metal components can be dissolved through acid and collected for further utilization; siC can be directly recycled and reused, and the cost of the whole service cycle is low. The catalyst takes hydrophobic functional group modified SiC as a carrier, has extremely strong hydrophobicity, can solve the problem of rapid discharge of water formed by hydroxide, and avoids catalyst deactivation.

Description

Technical Field

[0001] The present application relates to the technical field of hydrogen deoxygenation and purification, and in particular to a catalyst for hydrogen deoxygenation and purification, a method for preparing a catalyst for hydrogen deoxygenation and purification, and an application of a catalyst for hydrogen deoxygenation and purification. Background Art

[0002] As a new type of clean, low-carbon energy carrier, hydrogen energy is abundant in resources and does not emit pollutants. In recent years, with the rapid development of electronics, semiconductors, fuel cells and other fields, the demand for high-purity hydrogen has increased significantly. Coke oven gas is rich in hydrogen. Through appropriate treatment processes, high-purity hydrogen can be extracted from coke oven gas. The method of extracting hydrogen from coke oven gas is not only low-cost, but also mature in technology. It is a large-scale and low-cost by-product of liquid hydrogen supply, and is regarded as an important industrial hydrogen production method.

[0003] The process of hydrogen production from coke oven gas mainly includes desulfurization and denaphthalene, compression pretreatment, pressure swing adsorption hydrogen production, deoxygenation and drying, among which hydrogen deoxygenation and purification is a very critical step. Catalytic deoxygenation is one of the main methods for hydrogen purification in industry. Catalytic deoxygenation refers to the reaction of oxygen in hydrogen with hydrogen under the action of a catalyst to generate water, and then the water is removed by adsorption and drying. The catalytic deoxygenation method has a simple principle, easy operation and low equipment cost.

[0004] At present, the catalyst commonly used in the catalytic deoxygenation method is Pd (palladium) or Pt (platinum) catalyst. At present, the carriers of Pd catalysts mainly include Al2O3 (aluminum oxide), activated carbon and molecular sieves, but the water formed by the Pd catalysts loaded by these carriers during the catalytic reaction will cover the surface of the metal particles, causing the catalyst to be deactivated. In addition, the above-mentioned catalytic deoxygenation reaction is an exothermic reaction and is prone to spontaneous combustion or explosion.

[0005] It can be seen that the existing technology still needs to be improved and enhanced. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a catalyst for hydrogen deoxygenation purification and a preparation method and application thereof, aiming to avoid the problem in the prior art that the catalyst for hydrogen deoxygenation purification is deactivated by the water generated by the reaction during the deoxygenation process.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] On one hand, the present application discloses a catalyst for deoxygenation and purification of hydrogen, wherein the catalyst comprises SiC (silicon carbide) modified with hydrophobic functional groups as a carrier, and an active component Pd supported on the carrier.

[0009] In some embodiments of the present application, the SiC and the modifier are modified by one or more of esterification reaction, acylation reaction or etherification reaction to obtain the carrier.

[0010] In some embodiments of the present application, the modifier includes a combination of one or more of acetic anhydride, succinic anhydride, dodecenylsuccinic anhydride, 2-octen-1-ylsuccinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate, and 1-bromohexadecane.

[0011] In some embodiments of the present application, in the catalyst, the content of Pd is 0.1 to 10 wt %.

[0012] In some embodiments of the present application, in the catalyst, Pd exists in the form of a single atom or a cluster.

[0013] On the other hand, the present application also provides a method for preparing a catalyst for deoxygenation and purification of hydrogen, the preparation method comprising:

[0014] Hydrophobic modification of SiC surface: Weigh a certain amount of SiC and disperse it in a mixed solvent of water and ethanol, stir evenly, adjust the pH to 8.5-9, slowly add the modifier, adjust the pH to 7 after sufficient reaction, wash and dry to obtain hydrophobic modified SiC;

[0015] Preparation of SiC-based Pd catalyst: Take a certain amount of hydrophobically modified SiC and disperse it in deionized water, add a certain amount of chloropalladic acid solution according to the required loading amount, stir evenly, react at low temperature for 0.5 to 2 hours to obtain a Pd / SiC composite, wash the Pd / SiC composite with water and ethanol in turn, and dry it to obtain a Pd / SiC catalyst.

[0016] In some embodiments of the present application, the SiC is hydrophobically modified by a combination of one or more of acetic anhydride, succinic anhydride, dodecenylsuccinic anhydride, 2-octen-1-ylsuccinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate, and 1-bromohexadecane.

[0017] In some embodiments of the present application, the preparation method further comprises: after obtaining the hydrophobically modified SiC, repeating the step of hydrophobic modification of the SiC surface.

[0018] In some embodiments of the present application, a quantitative amount of chloropalladic acid solution is added according to the required loading amount, stirred evenly, and reacted for 0.5 to 2 hours under low temperature conditions, specifically comprising:

[0019] A quantitative amount of chloropalladium acid solution is added according to the required loading amount, stirred evenly, ethanol and liquid nitrogen are introduced into the reactor, and the reaction is irradiated with ultraviolet light for 0.5 to 2 hours.

[0020] In some embodiments of the present application, the Pd / SiC composite is washed with water and ethanol in sequence, and dried to obtain a Pd / SiC catalyst, specifically comprising:

[0021] The Pd / SiC composite was washed with water and ethanol in sequence, and then placed in a vacuum drying oven at a temperature of 60° C. for drying for 6 to 12 hours to obtain a Pd / SiC catalyst.

[0022] Another aspect of the present application also provides an application of a catalyst for deoxygenation and purification of hydrogen, wherein the catalyst as described in any one of the above items is applied to deoxygenation and purification of hydrogen in a hydrogen production process.

[0023] In some embodiments of the present application, the deoxygenation purification process is carried out under normal pressure, the reaction temperature is less than 50°C, and the air velocity is 9000-15000h -1 .

[0024] Beneficial effects:

[0025] The catalyst for hydrogen deoxygenation and purification provided in the present application uses SiC as a carrier, has the advantages of good thermal conductivity, high temperature resistance and acid-base corrosion resistance, and can better disperse and stabilize the active component Pd loaded on the surface. There are hydrogen overflow and oxygen overflow phenomena on the SiC surface, which can be used as an active surface for hydrogen-oxygen reactions. The unique physical and chemical properties of SiC can prevent the occurrence of overheating during catalytic deoxygenation, effectively control the reaction rate, improve metal utilization, and reduce the cost of use. In addition, since SiC is resistant to acid and alkali corrosion, when the catalyst is deactivated, the metal components can be dissolved by acid and further utilized after collection; and SiC can also be directly recycled and reused, and the cost of the entire use cycle is low. The catalyst uses SiC modified with hydrophobic functional groups as a carrier, has extremely strong hydrophobicity, and can solve the problem of rapid discharge of water formed by hydroxides.

[0026] The present application provides a method for preparing a catalyst for deoxygenation and purification of hydrogen, which utilizes a low-temperature liquid phase reduction method to load Pd on a SiC surface modified with a hydrophobic functional group to prepare a Pd / SiC catalyst, so that the obtained catalyst has a smaller particle size, a larger specific surface area, can load Pd more effectively, and has extremely strong hydrophobicity, effectively avoiding the problem of catalyst deactivation due to the formation of water by hydroxides in the reaction.

[0027] The catalyst for hydrogen deoxygenation and purification provided in the present application can be used in the industrial hydrogen deoxygenation and purification process with an oxygen content of less than 1000 ppm, and can achieve a good catalytic deoxygenation effect at low temperature and normal pressure. DETAILED DESCRIPTION

[0028] The present application provides a catalyst for deoxygenation and purification of hydrogen, and a preparation method and application thereof. In order to make the purpose, technical solution and effect of the present application clearer and more specific, the present application is further described in detail with examples below. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application.

[0029] On the one hand, the present application provides a catalyst for hydrogen deoxygenation and purification, which can be used in the deoxygenation and purification step in the process of extracting high-purity hydrogen from coke oven gas. It can effectively remove oxygen from hydrogen raw gas by catalytic oxidation at low temperature and normal pressure, has high catalytic efficiency and high safety in use, and has important development significance.

[0030] Specifically, the catalyst includes a SiC carrier precisely modified with hydrophobic functional groups, and an active component Pd loaded on the carrier.

[0031] As a carrier, SiC has the advantages of good thermal conductivity, high temperature resistance and acid and alkali corrosion resistance, thus enhancing the stability and durability of the catalyst. Since SiC is resistant to acid and alkali corrosion, when the catalyst is deactivated, the metal components can be dissolved by acid and collected for further use; SiC can also be directly recycled and reused, with low cost throughout the entire life cycle.

[0032] In addition, SiC has good compatibility with the metal matrix, which can effectively enhance the mechanical strength and thermal stability of the metal matrix, and can better disperse and stabilize the active component Pd loaded on the surface, thereby further improving the overall performance of the catalyst.

[0033] There is hydrogen overflow and oxygen overflow phenomenon on the SiC surface, which can serve as an active surface for hydrogen-oxygen reaction and improve the catalytic effect of the catalyst.

[0034] SiC is modified with hydrophobic functional groups, so that the generated catalyst has good hydrophobic properties, which can effectively avoid the water formed during the deoxygenation reaction covering the surface of the metal particles and causing catalyst deactivation, as well as spontaneous combustion or explosion caused by the reaction exothermicity.

[0035] Pd has high catalytic activity in catalytic oxidation reactions, can selectively catalyze the formation of target products, avoid the generation of by-products, and does not need to react under high temperature and high pressure conditions. It has high stability and is not easily affected by the environment. In addition, Pd also has a long service life, can be recycled many times, has good regeneration, and can be regenerated by simple methods, reducing production costs.

[0036] In some embodiments, SiC can be reacted with a modifier through one or more of an esterification reaction, an acylation reaction, or an etherification reaction to obtain a catalyst carrier.

[0037] SiC can be modified once to obtain the catalyst carrier, or SiC can be modified twice or more to obtain the catalyst carrier. When SiC is modified multiple times, the multiple modifications can use the same type of reaction or different types of reactions. It is understood that when SiC is modified multiple times by the same type of reaction, different modification reactions use different modifiers.

[0038] By modifying the SiC multiple times, the deoxidation effect of the catalyst can be further improved to a certain extent, the surface structure of SiC can be improved, and the hydrophobic effect of the SiC surface can be improved, thereby increasing the service life of the catalyst.

[0039] In some embodiments, the modifier can be selected from but not limited to acetic anhydride, succinic anhydride, dodecenyl succinic anhydride, 2-octen-1-yl succinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate, 1-bromohexadecane, or one or more combinations thereof. When SiC needs to be modified multiple times, different modifiers can be selected to react successively.

[0040] For example, acetic anhydride can react with a compound containing active hydrogen atoms to introduce an acetyl group. The acetyl group is a hydrophobic functional group. The reaction of SiC with acetic anhydride can modify the SiC surface with the acetyl group, thereby making the SiC surface hydrophobic.

[0041] 2-Propyl glycidyl ether is a hydrophobic compound that can react with hydrogen atoms on the SiC surface through reaction mechanisms such as acylation to introduce hydrophobic propyl glycidyl ether groups into the silicon carbide surface, thereby achieving hydrophobic modification of SiC.

[0042] Hexadecanoyl chloride contains a hydrophobic group, a hexadecyl group. After the active group is introduced on the SiC surface, it can react with the hexadecanoyl chloride to introduce the hexadecyl group into the silicon carbide surface to achieve hydrophobic modification.

[0043] In some embodiments, the content of Pd in ​​the catalyst is 0.1-10wt%. The Pd loading is controlled within the above range, so that the catalyst has good controllability in the hydrogen deoxygenation purification reaction. In addition, the catalyst with the above Pd loading can achieve an effective catalytic deoxygenation effect in the industrial hydrogen deoxygenation purification process with an oxygen content of less than 1000ppm, and the oxygen content in the purified hydrogen is less than 1.0ppm.

[0044] Furthermore, in the catalyst, Pd exists in the form of single atoms or clusters. This unique form of existence allows Pd atoms to maximize their catalytic activity, because single atoms or small clusters of Pd have higher surface energy and more active sites, which can significantly improve the efficiency and selectivity of the catalytic reaction. In addition, since the Pd atoms are very evenly dispersed in the catalyst, this helps prevent agglomeration between Pd atoms, thereby maintaining the stability and long-term service life of the catalyst. This dispersed Pd catalyst oxidation reaction can exhibit excellent catalytic performance, providing an efficient and economical solution for industrial catalytic processes.

[0045] On the other hand, the present application also provides a method for preparing a catalyst for hydrogen deoxygenation purification. Specifically, the preparation method comprises:

[0046] S100. Hydrophobic modification of SiC surface: Weigh a certain amount of SiC and disperse it in a mixed solvent of water and ethanol, wherein the volume ratio of water to ethanol is 1:1. Stir evenly, adjust the pH of the solution to 8.5-9 with 0.1M NaOH, and slowly add the modifier diluted with an equal volume of ethanol; continue stirring and reacting at 35°C for 1h. After sufficient reaction, adjust the pH to 7 with 0.1M HCl, wash and dry to obtain hydrophobically modified SiC.

[0047] When SiC is dissolved in a mixed solvent of water and ethanol, active atoms can be obtained on the surface of SiC, so that it can better combine with the modifier to obtain hydrophobic functional groups. After modification, the surface properties of SiC are improved, which can increase the hydrophobicity of the catalyst, thereby reducing the possibility of water poisoning the catalyst produced by the hydrogen oxidation reaction and increasing the service life of the catalyst.

[0048] Further, in the process of modifying SiC, a variety of different modifiers can be selected to achieve the optimization of its surface characteristics. These modifiers include but are not limited to acetic anhydride, succinic anhydride, dodecenyl succinic anhydride, 2-octen-1-yl succinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate and 1-bromohexadecane etc. These modifiers can be used alone, or two or more thereof can be used in combination according to specific needs and expected modification effects. In this way, the surface chemical properties of silicon carbide can be effectively adjusted to improve the hydrophobic properties of its surface, thereby improving the service life of the catalyst.

[0049] Further, when two or more modifiers are used to modify SiC, the same reaction type can be used successively, or different reaction types can be used to modify SiC. The reaction between SiC and the modifier can be, but is not limited to, one or more of esterification, acylation or etherification. That is, when SiC needs to be modified twice or more, the above-mentioned step of hydrophobic modification of the SiC surface can be repeated after obtaining the hydrophobically modified SiC.

[0050] S200. Preparation of SiC-based Pd catalyst: Take a certain amount of hydrophobically modified SiC and disperse it in deionized water, add a certain amount of chloropalladic acid solution according to the required loading amount, stir evenly, react at low temperature for 0.5 to 2 hours to obtain a Pd / SiC complex, wash the Pd / SiC complex with water and ethanol in turn, and dry it to obtain a Pd / SiC catalyst.

[0051] In the above, Pd is loaded onto the surface of hydrophobically modified SiC by liquid phase reduction method under low temperature conditions, which enables Pd to be loaded more evenly on the surface of SiC, and the generated catalyst particles are smaller, thereby increasing the specific surface area of ​​the catalyst and thus improving the catalytic performance.

[0052] Specifically, during the process of loading Pd onto SiC, the reactor is placed in an ethanol atmosphere and cooled by introducing liquid nitrogen.

[0053] In the process of Pd loading to SiC, in order to ensure the smooth progress of the reaction and prevent the material from being damaged by excessive temperature, the present application is to place the reactor in an ethanol atmosphere and pass liquid nitrogen to effectively cool the reaction. Liquid nitrogen is a very low temperature coolant that can quickly reduce the temperature in the reactor to avoid the adverse effects of high temperature on Pd and SiC. However, the temperature of liquid nitrogen is too low and not easy to control. Mixing liquid nitrogen into ethanol can slow down the cooling rate of liquid nitrogen and help maintain the stability of the low temperature environment. The freezing point of ethanol is relatively low and it is not easy to solidify, which can ensure the continuous production of a mitigating effect on the volatilization rate of liquid nitrogen. Through this cooling method, the present application can accurately control the reaction temperature, ensure that Pd can be stably loaded on SiC, and maintain the integrity of its structure and performance.

[0054] At the same time, in order to further improve the cooling efficiency, the reactor may also be equipped with a heat exchanger or other cooling devices. These devices can further reduce the temperature of the cooling medium, thereby enhancing the cooling effect on the reactor. In the process of Pd loading onto SiC, cooling is not only a key step to ensure the smooth progress of the reaction, but also an important factor affecting the quality and performance of the final product.

[0055] In some embodiments, ethanol and liquid nitrogen can be stored in a Dewar flask.

[0056] Dewar flasks can effectively isolate external heat, reduce heat exchange between the contents and the outside world, and maintain the temperature of internal substances. Ethanol is liquid at room temperature and is volatile, so special attention should be paid to sealing and temperature control during storage. Liquid nitrogen has a boiling point of -196°C and is an ultra-low temperature liquid, which requires extremely high insulation performance of the storage container. Since the vacuum layer inside the Dewar flask can effectively prevent heat conduction and convection, it can provide a stable low-temperature environment for ethanol and liquid nitrogen, preventing them from undergoing unnecessary physical changes such as evaporation or freezing due to the influence of external temperature. In addition, the outer shell of the Dewar flask is usually made of metal or other strong materials and can withstand a certain pressure, which is especially important for storing liquid nitrogen, because liquid nitrogen will evaporate rapidly at room temperature and produce higher pressure.

[0057] Furthermore, when Pd is loaded onto a SiC carrier, it reacts under the irradiation of ultraviolet light. Ultraviolet light has high energy, and under the irradiation of ultraviolet light, the interface between Pd and SiC can absorb the energy of ultraviolet light, and the Pd precursor is reduced to Pd particles. The surface of SiC can support the Pd particles and prevent the Pd particles from agglomerating, so that Pd can be loaded on the carrier surface in the form of single atoms or clusters.

[0058] In another embodiment, when Pd is loaded onto a SiC carrier, it can also react under the irradiation of visible light, but the energy of visible light is not as high as that of ultraviolet light, so the loading effect of Pd will be reduced accordingly.

[0059] Furthermore, the Pd / SiC composite is washed with water and ethanol in turn and then placed in a vacuum drying oven at a temperature of 60°C for 6 to 12 hours. The vacuum drying oven at 60°C can stably maintain the drying temperature of the Pd / SiC composite, so that the Pd / SiC composite can be dried evenly. In addition, setting the drying temperature to 60°C can avoid excessively high temperatures that may damage the surface of silicon carbide or produce adverse effects. Since it takes a long time to dry SiC at 60°C, the above drying time can ensure the dryness of the obtained Pd / SiC catalyst, thereby ensuring that the catalyst has good catalytic activity and extending the service life of the catalyst.

[0060] Another aspect of the present application also provides an application of a catalyst for deoxygenation and purification of hydrogen, wherein the catalyst as described above is applied to the deoxygenation and purification of hydrogen in a hydrogen production process. For example, the catalyst can be applied to the deoxygenation and purification process of hydrogen in hydrogen production from coke oven gas.

[0061] In some embodiments, the catalyst can be used in an industrial hydrogen deoxygenation purification process with an oxygen content of less than 1000 ppm.

[0062] Specifically, the catalyst can be used in the deoxygenation and purification process of hydrogen under normal pressure, with a reaction temperature of less than 50°C and a space velocity of 9000 to 15000 h -1 , realizing the hydrogen production process under normal pressure and low temperature, reducing the energy consumption of hydrogen production.

[0063] The oxygen content in the hydrogen after being purified by the above catalyst can be less than 1.0 ppm. That is, the catalyst provided in the present application can be applied to industrial hydrogen deoxygenation purification to achieve a good catalytic deoxygenation effect at low temperature and normal pressure.

[0064] The present application is described in more detail below through examples and comparative examples, but the present application is not limited to the following examples.

[0065] Example 1

[0066] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solvent of deionized water and ethanol with a volume ratio of 1:1 and stir for 30min; then adjust the pH value of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of acetic anhydride diluted with an equal volume of ethanol; continue stirring and reacting at 35℃ for 1h. Neutralize it with 0.1M HCl to a pH of 7, wash it with water and ethanol successively, and dry it to obtain hydrophobically modified SiC.

[0067] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 0.5 wt%.

[0068] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 0.9 ppm.

[0069] Example 2

[0070] 10g SiC was ultrasonically dispersed in 100mL of a mixed solution of deionized water and ethanol in a volume ratio of 1:1, and stirred for 30min; then the pH of the solution was adjusted to 8.5-9 with 0.1M NaOH, and 1g of acetic anhydride diluted with an equal volume of ethanol was slowly added, and the reaction was continued at 35°C with stirring for 1h. It was neutralized to pH 7 with 0.1M HCl, washed with water and ethanol successively, and dried to obtain hydrophobically modified SiC.

[0071] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 9.4 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10 ° C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60 ° C to obtain a Pd / SiC catalyst with a Pd content of 1 wt%.

[0072] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 1 wt% was loaded into a fixed bed reactor, and a hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45°C, the pressure was normal, and the air velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 0.78 ppm.

[0073] Example 3

[0074] 10g SiC was ultrasonically dispersed in 100mL of a mixed solution of deionized water and ethanol with a volume ratio of 1:1, and stirred for 30min; then the pH of the solution was adjusted to 8.5-9 with 0.1M NaOH, and 1g of hexadecanoyl chloride diluted with an equal volume of ethanol was slowly added, and the reaction was continued at 35°C with stirring for 1h. It was neutralized to pH 7 with 0.1M HCl, washed with water and ethanol successively, and dried to obtain hydrophobically modified SiC.

[0075] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 0.5 wt%.

[0076] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 0.86 ppm.

[0077] Example 4

[0078] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solution of deionized water and ethanol with a volume ratio of 1:1, and stir for 30min; then adjust the pH of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of acetic anhydride diluted with an equal volume of ethanol, and continue stirring and reacting at 35°C for 1h. Finally, neutralize it with 0.1M HCl to pH 7, wash it with water and ethanol successively, and dry it; then use dodecenyl succinic anhydride as a modifier, and further modify the obtained SiC according to the above steps to enhance the hydrophobicity of the carrier, and obtain secondary hydrophobically modified SiC.

[0079] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 0.5 wt%.

[0080] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions. The oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was 0.80 ppm.

[0081] Example 5

[0082] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solution of deionized water and ethanol with a volume ratio of 1:1, and stir for 30min; then adjust the pH of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of hexadecanoyl chloride diluted with an equal volume of ethanol, and continue stirring and reacting at 35°C for 1h. Neutralize it with 0.1M HCl to pH 7, wash it with water and ethanol successively, and dry it; then use diethyl maleate as a modifier, and further modify the obtained SiC according to the above steps to enhance the hydrophobicity of the carrier, and obtain a secondary hydrophobically modified SiC.

[0083] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 0.5 wt%.

[0084] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions. The oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was 0.75 ppm.

[0085] Example 6

[0086] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solvent of deionized water and ethanol with a volume ratio of 1:1 and stir for 30min; then adjust the pH value of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of acetic anhydride diluted with an equal volume of ethanol; continue stirring and reacting at 35℃ for 1h. Neutralize it with 0.1M HCl to a pH of 7, wash it with water and ethanol successively, and dry it to obtain hydrophobically modified SiC.

[0087] Weigh 999 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.002 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10 ° C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60 ° C to obtain a Pd / SiC catalyst with a Pd content of 0.1 wt%.

[0088] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.1 wt% was loaded into a fixed bed reactor, and a hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, the pressure was normal, and the air velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 2.8 ppm.

[0089] Example 7

[0090] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solvent of deionized water and ethanol with a volume ratio of 1:1 and stir for 30min; then adjust the pH value of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of acetic anhydride diluted with an equal volume of ethanol; continue stirring and reacting at 35℃ for 1h. Neutralize it with 0.1M HCl to a pH of 7, wash it with water and ethanol successively, and dry it to obtain hydrophobically modified SiC.

[0091] Weigh 950 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 9.4 mL of 0.05 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10 ° C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60 ° C to obtain a Pd / SiC catalyst with a Pd content of 5 wt%.

[0092] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 0.56 ppm.

[0093] Example 8

[0094] Weigh 10g SiC and ultrasonically disperse it in 100mL of a mixed solvent of deionized water and ethanol with a volume ratio of 1:1 and stir for 30min; then adjust the pH value of the solution to 8.5-9 with 0.1M NaOH, slowly add 1g of acetic anhydride diluted with an equal volume of ethanol; continue stirring and reacting at 35℃ for 1h. Neutralize it with 0.1M HCl to a pH of 7, wash it with water and ethanol successively, and dry it to obtain hydrophobically modified SiC.

[0095] Weigh 900 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 9.4 mL of 0.1 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 10 wt%.

[0096] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 10 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions, and the oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was found to be 0.51 ppm.

[0097] Comparative Example 1

[0098] Weigh 995 mg of the prepared SiC in a beaker, ultrasonically disperse it in deionized water, add 4.7 mL of 0.01 M chloropalladic acid solution, stir evenly, place the beaker in a Dewar flask filled with ethanol solution, gradually add liquid nitrogen to adjust the temperature to -10°C, irradiate with ultraviolet light for 1 h, wash with water and ethanol in turn after the reaction, and dry it in a vacuum drying oven at 60°C to obtain a Pd / SiC catalyst with a Pd content of 0.5 wt%.

[0099] The above catalyst was used in the hydrogen deoxygenation process: 50 mg of the above Pd / SiC catalyst with a Pd content of 0.5 wt% was loaded into a fixed bed reactor, and hydrogen feed gas with an oxygen content of 400 ppm was introduced. The temperature was controlled at 45 ° C, atmospheric pressure, and the space velocity was 10000 h -1 The catalytic deoxygenation reaction was carried out under the following conditions. The oxygen content in the tail gas at the reactor outlet was detected by gas chromatography, and the oxygen content in the tail gas was 6.16 ppm.

[0100] The deoxygenation and purification effects of the catalysts prepared in Examples 1 to 5 and Comparative Example 1 in the hydrogen deoxygenation reaction are shown in Table 1.

[0101] Table 1:

[0102]

[0103] It can be seen from Example 1, Example 2, Examples 6 to 8 and Table 1 that increasing the loading of Pd on the carrier surface can improve the deoxygenation and purification effect of the catalyst to a certain extent. When the loading of Pd in ​​the Pd / SiC catalyst reaches 0.5wt%, the catalyst can reduce the content of oxygen to less than 1ppm in the hydrogen deoxygenation reaction, effectively improving the purity of the finished hydrogen. However, by comparing the data of Example 7 and Example 8, it can be seen that when the loading of Pd in ​​the Pd / SiC catalyst is 5wt% and the loading of Pd in ​​the Pd / SiC catalyst is 10wt%, the deoxygenation effect is not much different. In Example 6, the Pd loading content can reduce the oxygen concentration in hydrogen to a very low concentration. When the oxygen concentration is already very low, the increase in the Pd loading in the catalyst does not have a great effect on the removal effect of oxygen. Therefore, based on the economic benefits of the catalyst, it is sufficient to control the loading of Pd in ​​the catalyst within the scope disclosed in this application.

[0104] It can be seen from Example 1, Example 3, Example 4 and Example 5 and Table 1 that, when the Pd loading amount remains unchanged, the secondary hydrophobic modification of SiC can improve the deoxidation and purification effect of the Pd / SiC catalyst to a certain extent. In addition, the multiple hydrophobic modifications of SiC can further improve the surface structure of SiC, further improve its hydrophobicity, and thereby reduce the possibility of the catalyst being poisoned and deactivated due to the generation of water by the hydrogen-oxygen reaction, thereby improving the service life of the catalyst.

[0105] It can be seen from Example 1, Example 3, Comparative Example 1 and Table 1 that the SiC in Comparative Example 1 is not hydrophobically modified before loading Pd. Therefore, when it is used for hydrogen deoxygenation reaction under the same experimental conditions as in Example 1 and Example 3, the concentration of oxygen in the tail gas generated is as high as 6.16 ppm, while the concentration of oxygen in the tail gas generated in Example 1 and Example 3 is less than 1 ppm, ensuring the safety of hydrogen application.

[0106] In summary, the present application uses a low-temperature liquid phase reduction method to load Pd on a SiC surface modified with a hydrophobic functional group to prepare a Pd / SiC catalyst, so that the obtained catalyst has a smaller particle size, a larger specific surface area, can load Pd more effectively, and has extremely strong hydrophobicity, effectively avoiding the problem of catalyst deactivation caused by the formation of water by hydroxides in the reaction. The catalyst is used in the hydrogen deoxygenation purification process, and can achieve a good catalytic deoxygenation effect at low temperature and normal pressure, proving the safety of hydrogen application.

[0107] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and application concept of the present application, and all these changes or substitutions should fall within the protection scope of the claims attached to the present application.

Claims

1. A catalyst for deoxygenation and purification of hydrogen, characterized in that: The catalyst comprises SiC modified with hydrophobic functional groups as a carrier and an active component Pd loaded on the carrier.

2. The catalyst according to claim 1, characterized in that The SiC and the modifier are modified by one or more of esterification reaction, acylation reaction or etherification reaction to obtain the carrier.

3. The catalyst according to claim 2, characterized in that The modifier includes one or more of acetic anhydride, succinic anhydride, dodecenylsuccinic anhydride, 2-octen-1-ylsuccinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate, and 1-bromohexadecane.

4. The catalyst according to claim 1, characterized in that In the catalyst, the content of Pd is 0.1-10 wt %.

5. The catalyst according to claim 1, characterized in that In the catalyst, Pd exists in the form of single atom or cluster.

6. A method for preparing a catalyst for deoxygenation and purification of hydrogen, characterized in that: The preparation method comprises: Hydrophobic modification of SiC surface: Weigh a certain amount of SiC and disperse it in a mixed solvent of water and ethanol, stir evenly, adjust the pH to 8.5-9, slowly add the modifier, adjust the pH to 7 after sufficient reaction, wash and dry to obtain hydrophobic modified SiC; Preparation of SiC-based Pd catalyst: Take a certain amount of hydrophobically modified SiC and disperse it in deionized water, add a certain amount of chloropalladic acid solution according to the required loading amount, stir evenly, react at low temperature for 0.5 to 2 hours to obtain a Pd / SiC composite, wash the Pd / SiC composite with water and ethanol in turn, and dry it to obtain a Pd / SiC catalyst.

7. The preparation method according to claim 6, characterized in that: The SiC is hydrophobically modified by a combination of one or more of acetic anhydride, succinic anhydride, dodecenylsuccinic anhydride, 2-octen-1-ylsuccinic anhydride, maleic anhydride, octadecanoyl chloride, hexadecanoyl chloride, 2-propyl glycidyl ether, diethyl maleate, dibutyl maleate, and 1-bromohexadecane.

8. The preparation method according to claim 6, characterized in that: The preparation method further comprises: after obtaining the hydrophobically modified SiC, repeating the step of hydrophobically modifying the surface of SiC.

9. The preparation method according to claim 6, characterized in that: The method comprises adding a certain amount of chloropalladic acid solution according to the required loading amount, stirring evenly, and reacting for 0.5 to 2 hours under low temperature conditions, specifically comprising: A quantitative amount of chloropalladium acid solution is added according to the required loading amount, stirred evenly, ethanol and liquid nitrogen are introduced into the reactor, and the reaction is irradiated with ultraviolet light for 0.5 to 2 hours.

10. The preparation method according to claim 6, characterized in that: The method comprises washing the Pd / SiC composite with water and ethanol in sequence, and drying to obtain a Pd / SiC catalyst, specifically comprising: The Pd / SiC composite was washed with water and ethanol in sequence, and then placed in a vacuum drying oven at a temperature of 60° C. for drying for 6 to 12 hours to obtain a Pd / SiC catalyst.

11. An application of a catalyst for deoxygenation and purification of hydrogen, characterized in that: The catalyst as claimed in any one of claims 1 to 10 is used for deoxygenation and purification of hydrogen in a hydrogen production process.

12. The use according to claim 11, characterized in that: The deoxygenation purification process is carried out under normal pressure, the reaction temperature is less than 50°C, and the air velocity is 9000-15000h -1 .

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