Anti-carbon-deposition porous carbon-loaded multi-alloy catalyst

Abstract

The invention discloses an anti-carbon-deposition porous carbon-loaded multi-alloy catalyst, and belongs to the technical field of energy catalysis. The catalyst is applied to tar catalytic cracking hydrogen production. The catalyst takes porous carbon as a carrier, active centers of Ni, Co and Fe are loaded on the carrier at the same time, and the catalyst has a pore channel structure in which micropores are partially communicated and mesopores are partially communicated. The process is simple, the cost is low, the catalyst has high activity and long service life, the catalyst is suitable for resource utilization of biomass tar and organic waste, a new technical approach is provided for efficient utilization of biomass energy, the key technical problems that the catalyst is prone to inactivation, low in catalytic efficiency and the like are solved, and the method is suitable for industrial production. The method has remarkable technical innovation and practical application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-value utilization of biomass resources and clean energy technology, and particularly relates to a porous carbon supported multi-alloy catalyst with anti-accumulation of carbon. BACKGROUND

[0002] Hydrogen energy, as a recognized core component of future renewable energy, plays a key role in global energy transformation. Its combustion product is only water, with zero pollution and greenhouse gas emissions, making it an ideal choice for addressing climate change and building a green energy system. Governments and enterprises around the world are actively investing in hydrogen energy technology research and development, striving to establish a hydrogen economy in the future. Hydrogen energy not only helps to achieve energy structure diversification, but also promotes clean energy transformation, and is a key link to achieve sustainable development. With the continuous maturation of technology and the gradual reduction of cost, the widespread application of hydrogen energy will provide new solutions to global energy crisis and environmental challenges.

[0003] Hydrogen production technology is an important part of hydrogen energy utilization. Currently, hydrogen production methods can be roughly divided into three categories: fossil fuel hydrogen production, water electrolysis hydrogen production, and biomass hydrogen production. However, coal hydrogen production and natural gas reforming hydrogen production account for more than 95% of current production capacity, but have high carbon emissions and do not meet the requirements of low-carbon development. Using renewable energy to generate electricity to electrolyze water produces high-purity products, but has high energy consumption and electricity cost, and is only suitable for areas with abundant green electricity. Biomass hydrogen production through pyrolysis and gasification technologies converts biomass into hydrogen-rich gas, combining the advantages of "carbon neutrality" and waste resourceization.

[0004] Biomass energy, as a widely available and renewable energy source, its thermochemical conversion is the main way of biomass energy utilization. However, the tar produced during the conversion process can block pipelines, corrode equipment, reduce system efficiency, and cause secondary pollution, severely restricting its large-scale application. Catalytic reforming technology can convert tar into hydrogen-rich gas, but traditional Ni-based catalysts are prone to carbon deposition and deactivation, so a low-cost, high-anti-carbon-effect, and long-service-life catalyst needs to be developed to replace existing hydrogen production catalysts. SUMMARY

[0005] In view of the problems of easy deactivation, low catalytic efficiency, and short service life of existing hydrogen production catalysts, the present application aims to provide a porous carbon supported multi-alloy catalyst with anti-accumulation of carbon. The material has stable structure, strong adsorption capacity, and specific surface area, and its special pore structure can greatly reduce the aggregation of metals on the surface of the carrier. At the same time, the partially interconnected multi-level pore structure cooperates with the loaded Ni, Co, and Fe active centers, greatly improving the anti-accumulation of carbon performance and catalytic efficiency of the catalyst when applied to tar catalytic cracking for hydrogen production, thereby significantly prolonging the service life of the catalyst.

[0006] In order to achieve the above technical purposes, the present application provides a porous carbon supported multi-alloy catalyst with anti-carbon deposition, which is applied to catalytic cracking of tar for hydrogen production; the catalyst has a porous carbon carrier, and the carrier is simultaneously loaded with Ni, Co and Fe active centers, and the catalyst has a pore structure with micropore and mesopore through-paths.

[0007] The catalyst of the present application has high catalytic capacity and anti-carbon deposition performance, mainly due to the special pore structure and the introduced Ni, Co and Fe active centers. The principle is that: on the one hand, the catalyst material after multiple modifications has a suitable micropore structure and mesopore structure, which is beneficial to the formation of multiple metal active sites of elemental Ni, Co and Fe on the surface and inside of the carrier, and simultaneously improves the structural stability of the catalyst, and the partially through-pore is more conducive to reducing carbon deposition; on the other hand, the loaded metal Ni can catalyze the oxidative decomposition of toluene, the interaction between highly dispersed Ni and activated carbon is strong, which can promote the adsorption and transfer of active hydrogen in the catalyst. Co has a rich electronic structure and variable oxidation state, which can provide a variety of active sites, and there is a synergistic effect between Ni and Co, which can optimize the electronic structure and surface properties of the catalyst, improve the activity and selectivity of the catalyst, and more importantly, the simultaneously introduced Fe active center can accelerate the reaction of CO2 or H2O with the surface carbon under the synergistic effect of the special pore structure, so that the carbon deposition is removed at the initial stage; at the same time, the dynamic valence change of Fe 2+ and Fe 3+ occurs in the reaction, which directly oxidizes the carbon deposition, thereby achieving the remarkable effect of inhibiting carbon deposition and maintaining the activity of the catalyst.

[0008] The catalyst of the present application has excellent catalytic performance and anti-carbon deposition performance, so that the toluene conversion rate of the porous carbon supported multi-alloy catalyst is 96%, and the service life can reach 14h.

[0009] As a preferred scheme, the preparation process of the catalyst is: after the biomass raw material is crushed, a preliminary carbonized material is obtained by carbonization, and then potassium carbonate is added for calcination treatment to obtain a porous carbon precursor; the porous carbon precursor is mixed and dried with a nickel source, a cobalt source and an iron source, and then calcined and reduced under a protective atmosphere to obtain the catalyst.

[0010] The application activates the preliminary carbonized material through K2CO3 mixed calcination, and high specific surface area biochar carriers can be generated at high temperature. In addition, CO2 generated by the decomposition of K2CO3 performs gas phase etching on the biochar skeleton to form a hierarchical pore structure with micropores and mesopores, and part of the micropores and mesopores form a through structure, and the specific surface area of the material is further increased. The obtained porous carbon precursor is calcined with a metal source (nickel source, cobalt source and iron source) at high temperature, and part of the porous carbon performs reduction on the metal source to load new structures on the porous carbon and obtain metal active sites with rich surface.

[0011] As a preferred scheme, the catalyst is prepared by crushing the biomass raw material, obtaining preliminary carbonized material through carbonization, adding potassium carbonate for calcination treatment to obtain a porous carbon precursor, and then mixing the porous carbon precursor with a nickel source, a cobalt source and an iron source and adding a reducing agent to perform a reduction reaction at room temperature.

[0012] The application can also use a strong reducing chemical reducing agent to reduce metal ions into metal elements in a solution, which has lower energy consumption than high-temperature calcination reduction, can deposit metal nanoparticles on the porous carbon carrier, and can make the metal active sites uniformly distributed.

[0013] As a preferred scheme, the carbonization conditions are that the temperature is 350-650 DEG C, the time is 1-4 h, and nitrogen gas with a flow rate of 80-100 mL / min is used as a protective atmosphere. The application can obtain a porous carbon precursor with high specific surface area and high pore structure through carbonization, which is beneficial to the subsequent loading of metals.

[0014] As a preferred scheme, the adding amount of potassium carbonate is 1-4 times the mass of the preliminary carbonized material. The amount of potassium carbonate needs to be particularly controlled in the application. If the amount of potassium carbonate is insufficient, it is difficult to form the pore structure with microporous and mesoporous parts through in the application, and the catalytic performance is low. If the amount of potassium carbonate is too high, the carbon itself and the reaction with it will occur, the carbon will be oxidized to generate the corresponding carbon oxides or carbonates, the skeleton will be etched, and the structure will collapse.

[0015] As a preferred scheme, the biomass raw material is derived from reed, and actual operations can select tobacco stems, corn stems, bamboo fibers, distiller's grains and the like.

[0016] As a preferred scheme, the porous carbon precursor is mixed with the metal source after acid pickling and impurity removal. Further acid pickling and impurity removal can remove the influence of metal impurity atoms in the biomass raw material on the material.

[0017] As a preferred scheme, the calcination treatment is performed at a temperature of 600-950°C for 1-4h, and nitrogen gas with a flow rate of 60-100mL / min is used as a protective atmosphere. By controlling the temperature and time of the calcination treatment, the potassium carbonate can be fully subjected to gas phase etching with the porous carbon to form hierarchical pores. Further preferably, the temperature is 800-900°C.

[0018] As a preferred scheme, the total mass ratio of the porous carbon precursor to the nickel source, the cobalt source and the iron source is 1:(1-10). Within the mass ratio range selected in the application, the introduction of active sites in the reaction is ensured, and the excessive amount of metal does not cause the blockage of the pore structure and the collapse of the structure, thereby reducing the specific surface area of the material and the catalytic performance. Further preferably, the mass ratio is 1:(1.5-5).

[0019] As a preferred scheme, the molar ratio of the nickel source, the cobalt source and the iron source is (3-8):(1-3):(1-2). When the amount of the iron source is too low in the application, the effect of inhibiting carbon deposition cannot be achieved, and when the amount of the iron source is too high, the active sites of the nickel source and the iron source are easily occupied, thereby reducing the activity of the catalyst. Therefore, the amount of the iron source is less than the total amount of the cobalt source and the nickel source to ensure the balance between the catalytic performance and the long service life. Further preferably, the molar ratio is (4-5):(1-2):(1-2).

[0020] As a preferred scheme, the nickel source is at least one of nickel chloride, nickel nitrate, nickel chloride hexahydrate and nickel nitrate hexahydrate; the cobalt source is at least one of cobalt chloride, cobalt nitrate, cobalt acetate, cobalt chloride hexahydrate, cobalt nitrate hexahydrate and cobalt acetate tetrahydrate; and the iron source is at least one of iron chloride, iron nitrate and iron nitrate nonahydrate.

[0021] As a preferred scheme, the calcination reduction is performed at a temperature of 550-950°C for 0.5-3h. The temperature and time of the calcination reduction in the application have a direct impact on the amount and uniformity of the metal active sites introduced on the porous carbon carrier. Too high a temperature can cause the generation of metal elements too fast, so that the metal elements cannot effectively react with the surface of the porous carbon, thus the specific surface area cannot be fully utilized, and the metal elements are accumulated and the pore structure is blocked. Too low a temperature can reduce the reaction rate, so that the metal active sites are generated slowly and the effect is poor. The length of time also affects the introduction rate of the metal active sites, and affects the structure and catalytic performance of the final sample. In the application, further preferably, the temperature of the high-temperature calcination is 600-800°C, and the reaction time is 1-1.5h. Still further preferably, the calcination temperature is 700-800°C.

[0022] As a preferred scheme, the reducing agent is at least one of sodium hypophosphite, sodium citrate and sodium borohydride, the mass ratio of the reducing agent to the porous carbon precursor is (0.5-3):1, and the reaction time of the reduction reaction is 1-4h.

[0023] As a preferred scheme, the catalyst is applied to catalytic cracking of tar to produce hydrogen, the reaction temperature is 450-950℃, the catalyst is 0.2-1g, tar (calculated by toluene, wherein the toluene concentration is 5000-6000ppm) and nitrogen as the balance gas are introduced. The catalyst of the application can achieve that the toluene conversion rate reaches 96% at 750℃, the catalyst stability reaches 14h at 700℃, and the toluene conversion rate still maintains above 90%. Further preferably, the catalytic temperature is 650-750℃.

[0024] The preparation method of the anti-carbon deposition porous carbon supported multi-alloy catalyst in the application specifically comprises the following steps:

[0025] (1) The biomass raw material is dried and broken into particles, and the preliminary carbonized material is obtained by carbonization under a nitrogen atmosphere;

[0026] (2) The preliminary carbonized material is calcined with potassium carbonate to obtain a porous carbon precursor;

[0027] (3) The porous carbon precursor, a nickel source, a cobalt source and an iron source are dissolved in water, ultrasonic mixing is performed, and then the mixture is filtered and dried in a vacuum drying box to obtain a mixed black powder.

[0028] (4) The black powder is calcined under a nitrogen atmosphere to obtain a Ni-Co-Fe carbon supported catalyst.

[0029] or specifically comprising the following steps:

[0030] (1) The biomass raw material is dried and broken into particles, and the preliminary carbonized material is obtained by carbonization under a nitrogen atmosphere;

[0031] (2) The preliminary carbonized material is calcined with potassium carbonate to obtain a porous carbon precursor;

[0032] (3) The porous carbon precursor, a nickel source, a cobalt source and an iron source are dissolved in water, ultrasonic mixing is performed, and then a reducing agent is added to carry out a reduction reaction at room temperature, and the mixture is filtered and dried to obtain a Ni-Co-Fe carbon supported catalyst.

[0033] Compared with the prior art, the application has the following beneficial effects:

[0034] (1) The catalyst has high catalytic performance: uniform metal active sites are formed on the porous carbon carrier, and it has high structural stability; the metal Ni loaded thereon can catalyze the oxidative decomposition of toluene; the highly dispersed Ni has strong interaction with the activated carbon, which can promote the adsorption and transfer of active hydrogen in the catalyst. Co has rich electronic structure and variable oxidation state, which can provide diverse active sites; meanwhile, there is a synergistic effect between Ni and Co, which can optimize the electronic structure and surface properties of the catalyst, and improve the activity and selectivity of the catalyst.

[0035] (2) The Fe active center introduced in the catalyst can accelerate the reaction of CO2 or H2O with the surface carbon under the synergistic effect of the micropore through and mesopore through channel structure, so that the coke is removed at the initial stage of formation; meanwhile, iron undergoes dynamic valence state change of Fe 2+ and Fe 3+ in the reaction, directly oxidizing the coke, so as to inhibit the coke deposition, greatly improve the anti-coking performance and catalytic efficiency of the catalyst when applied to the catalytic cracking of tar to produce hydrogen, and thus the service life of the catalyst can be significantly prolonged.

[0036] (3) The process for preparing the catalyst is simple, and the biomass material is used as the carbon precursor, so that the catalyst has the characteristics of low cost, green environmental protection and high economic benefit.

[0037] (4) The catalyst can efficiently crack tar to 96%, and has a service life of 14h; while reducing the yield of tar, the catalyst converts the tar into hydrogen-rich gas, realizes the resource utilization of waste, and can be applied to the pyrolysis treatment of other organic waste (such as plastic products), reduces environmental pollution, and realizes the conversion of "waste" to "energy". BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is a comparison chart of specific surface areas of the porous carbon precursors after activation and roasting of different mass ratios of potassium carbonate in Example 1.

[0039] Figure 2 It is a BET comparison chart of the porous carbon precursors C-K2CO3 (reed carbon-K2CO3 activation) prepared by activation and roasting at 800 DEG C in Example 2 and the original reed carbon.

[0040] Figure 3 It is a comparison chart of SEM of the original reed carbon (C) in Example 1 Figure 3 (a) and C-K2CO3 (b) obtained in Example 1. Figure 3

[0041] Figure 4 ​The Ni-Co-Fe carbon-supported catalyst prepared in Example 3 with a calcination temperature of 700℃ after reaction Figure 4 (a) Comparison chart of the Ni-Co carbon-supported catalyst prepared in Comparative Example 1 Figure 4 (b) SEM chart.

[0042] Figure 5 Comparison chart of the proportion of hydrogen in the gas after catalysis by the Ni-Co-Fe carbon-supported catalyst prepared in Example 3 with a calcination temperature of 700℃ and the Ni-Co carbon-supported catalyst prepared in Comparative Example 1. As can be seen from the chart, the addition of Fe can also improve the catalytic activity to a certain extent.

[0043] Figure 6 Catalytic activity (characterized by toluene conversion rate) of the Ni-Co-Fe carbon-supported catalyst prepared in Example 3 with a calcination temperature of 700℃ at different catalytic temperatures and stability of the catalyst at a catalytic temperature of 700℃. DETAILED DESCRIPTION

[0044] The present application will be further described below in conjunction with specific examples. It is apparent that the following described examples are only a part of the examples, and all other examples obtained by those skilled in the art without making creative efforts still fall within the protection scope of the present application.

[0045] Unless otherwise specified, various raw materials, reagents, instruments and equipment, etc. used in the present application can be purchased from the market or can be prepared by existing methods.

[0046] Example 1 (potassium carbonate amount exploration experiment)

[0047] The crushed and dried reed raw material was moved into a carbonization furnace, and carbonization was performed at a temperature of 400℃. High-purity nitrogen gas with a flow rate of 100 mL / min was introduced throughout the process for 2h. After carbonization and cooling, impurities were removed by sieving. The obtained material was washed with an aqueous solution, and impurities were removed by stirring and filtration. After washing, the biochar was dried again. The dried biochar was crushed using a ball mill to obtain the desired particle size of the preliminary carbonized material (raw reed carbon).

[0048] Take the preliminary carbonization material (C) and K2CO3 respectively for 1:1 and 1:2 mixed, fully ground and put into high temperature tube furnace, the experimental process is always in the flow of 80 mL / min of high purity nitrogen atmosphere, set temperature at 800℃, the heating rate is 5℃ / min, calcination 1h, the process continues to pass in 60 mL / min of high purity nitrogen, after cooling to room temperature, take out and put into beaker add water solution, using stirring device for fully stirring, then using suction filtration device to filter and dry the solution obtained by stirring and get the K2CO3 activated porous carbon precursor (C-K2CO3), the results are as follows Figure 1 and Table 1.

[0049]

[0050] From Figure 1 and Table 1, when the mixing mass ratio is 1:2, the specific surface area of the activated porous carbon precursor is larger, and the activity is stronger.

[0051] Example 2 (specific surface area exploration experiment)

[0052] The broken and dried reed raw material is moved into the carbonization furnace, the temperature is set to 400℃ for carbonization, the carbonization time is 1h, the flow of high purity nitrogen is 100mL / min throughout the process, after carbonization and cooling, the impurities are removed by screening, the obtained material is washed with water solution, the impurities are removed by stirring and filtering. After washing, the biochar is dried again, and the dried biochar is crushed by ball mill to obtain the desired particle size of the preliminary carbonization material (raw reed carbon).

[0053] Take the preliminary carbonization material and K2CO3 for 1:2 mixed, fully ground and put into high temperature tube furnace, pass in 10 minutes 144mL / min of high purity nitrogen to remove the air in the device, set the activation calcination temperature to 800℃, the heating rate is 5℃ / min, calcination 1h, the process continues to pass in 60 mL / min of high purity nitrogen, after cooling to room temperature, take out and put into beaker add water solution, using stirring device for fully stirring, then using suction filtration device to filter and dry the solution obtained by stirring and get the K2CO3 activated porous carbon precursor (reed carbon-K2CO3 activation).

[0054] From Figure 2 the results show that under the condition of 800℃ calcination, the specific surface area of reed carbon-K2CO3 activation is greatly improved compared with the unactivated raw reed carbon.

[0055] Example 3

[0056] Preparation of anti-coking porous carbon loaded multi-alloy catalyst (Ni-Co-Fe carbon catalyst):

[0057] 0.952 g of NiCl₂·6H₂O, 0.291 g of Co(NO₃)₂·6H₂O, and 0.404 g of Fe(NO₃)₃·9H₂O (molar ratio of 4:1:1) were weighed and dissolved in 30 mL of deionized water. One g of the porous carbon precursor prepared in Example 2 was immersed in the mixed metal salt solution and ultrasonically treated. Stirring was performed on a magnetic stirrer to ensure uniform adsorption of the metal ions on the support. The impregnated sample was dried in an oven. The dried sample was placed in a tube furnace and calcined at 600°C, 700°C, and 800°C under a nitrogen atmosphere for 1 h to obtain the final catalysts at different temperatures.

[0058] Example 4

[0059] 0.952g NiCl2·6H2O, 0.291g Co(NO3)2·6H2O, and 0.404g Fe(NO3)3·9H2O (molar ratio of 4:1:1) were weighed and dissolved in 30mL of deionized water. 1g of the porous carbon precursor prepared in Example 2 was immersed in the mixed metal salt solution and sonicated. Stirring was performed on a magnetic stirrer to ensure uniform adsorption of the metal ions on the carbon support surface. The impregnated sample was dried in an oven. A 0.1M NaBH4 solution was prepared (0.5g NaBH4 dissolved in 50mL of deionized water). The dried sample was immersed in the NaBH4 solution and stirred at room temperature for 1 hour to reduce the metal ions. The sample was washed with deionized water and ethanol, dried in an oven, and cooled naturally to room temperature to obtain the final catalyst. This catalyst was used in toluene pyrolysis experiments, and its toluene catalytic efficiency was slightly lower than that of the catalyst obtained by calcination reduction in Example 3.

[0060] Comparative Example 1

[0061] The only difference between this comparative example and the catalyst prepared at a calcination temperature of 700° C. in Example 3 is that ferric nitrate nonahydrate is not added. The remaining steps and conditions are the same to obtain a carbon-supported nickel-cobalt catalyst.

[0062] Compare the SEM images of the catalyst of Example 3 and the catalyst of Comparative Example 1 after toluene pyrolysis experiment (the specific experimental steps and conditions are the same as those of the catalytic performance evaluation). Figure 4 . Figure 4 (a) shows the catalyst of Example 3 after the reaction. It can be seen that some flocculent carbon is accumulated on the surface, but metal active sites are still exposed on the surface, indicating that it still has strong catalytic ability. Figure 4 (b) shows the catalyst of Comparative Example 1 after the reaction. Obvious flocculent carbon deposits can be observed on the surface, and the metal active sites are almost invisible, which indicates that the addition of Fe in the present invention makes the catalyst have stronger resistance to carbon deposition.

[0063] Comparative Example 2

[0064] The difference between the comparative example and Example 2 is only that no potassium carbonate is added during the calcination process, and the rest of the steps and conditions are consistent, to obtain reed carbon which is not activated by potassium carbonate.

[0065] Figure 3(a) is an SEM photograph of Comparative Example 2, and it can be seen that the surface of the reed carbon is relatively smooth; Figure 3(b) is an SEM photograph of Example 2, and it can be seen that the surface of the activated carbon has obvious pore structure, and the BET is increased from 800 m 2 / g to 2000 m 2 / g, the specific surface area is significantly improved, and a super activated carbon is formed, such as Figure 1 .

[0066] Catalytic performance evaluation

[0067] The Ni-Co-Fe carbon-supported catalysts prepared in Example 3 at three different calcination temperatures and the catalyst prepared in Example 4 are evaluated for catalytic effect, as follows:

[0068] The catalyst is mixed with an appropriate amount of quartz sand (0.2 g of catalyst and 3 ml of quartz sand) and placed in a catalytic reaction container. Then, the catalyst catalytic activity experiment is performed, and a total gas flow of 160 mL / min of reaction gas is introduced, including: toluene concentration of 6000 ppm and nitrogen as balance gas. Through a programmed temperature process, the toluene concentration in the tail gas at each temperature is recorded, and the toluene conversion rate is calculated (in the present application, toluene is mainly converted into H2, a small part of CH4, C2H6, C3H6, which is measured by the toluene concentration before and after the reaction and the tail gas content. The toluene concentration can be detected by gas chromatography, and then the toluene conversion rate and hydrogen yield are calculated).

[0069] The toluene conversion rate and hydrogen yield of the Ni-Co-Fe carbon-supported catalysts of Example 3 at different calcination temperatures at a catalytic temperature of 700°C are shown in Table 2, as shown in Table 2. Figure 6 .

[0070] The examples demonstrate the activation effect of potassium carbonate on biochar and the influence of temperature on the reduction effect of the catalyst, and further optimize the carbon to potassium carbonate ratio to 1:2, and the calcination temperature to 700°C as the best conditions for preparing the catalyst, and Table 3 shows the toluene conversion rate of the catalyst at different temperatures for pyrolyzing toluene.

[0071] In Example 2, K2CO3 etches the reed carbon to form a gradient link pore channel (according to the pore size distribution), and the SEM photograph is as shown in Figure 2(b). The SEM photograph of the reed carbon which is not activated by K2CO3 in Comparative Example 2 is as shown in Figure 3(a). Figure 3 Figure 3 ​(a) By comparison, it can be found that the reed carbon activated by K2CO3 has a porous structure, providing a large number of metal attachment sites, while the surface of the unactivated reed carbon is relatively smooth. In terms of BET determination, the specific surface area of the activated reed carbon is 2000 m 2 / g, which is significantly improved compared to the unactivated reed carbon 800 m 2 / g, and the alloy has more anchoring sites.

[0072] In Comparative Example 1, under the same conditions, the SEM photos of the carbon-supported nickel-cobalt catalyst after reaction ( Figure 4 (b)) are compared with the SEM photos of the carbon-supported nickel-cobalt-iron catalyst after reaction in Example 3 ( Figure 4 (a)), it can be seen that the surface of the nickel-cobalt catalyst has obvious carbon deposition phenomenon, and carbon particles occupy the catalytic sites, reducing the activity of the catalyst; while the catalytic sites of the nickel-cobalt-iron catalyst do not have obvious carbon deposition phenomenon, and iron species (such as Fe, FeO x ) provide active sites, accelerate the reaction of CO2 or H2O with surface carbon, and make the carbon deposition be removed at the initial stage; at the same time, iron undergoes dynamic valence change of Fe 2+ and Fe 3+ in the reaction, directly oxidizing the carbon deposition. Thus, it is proved that the addition of Fe can inhibit carbon deposition and maintain the activity of the catalyst.

[0073]

[0074]

Claims

1. A carbon-deposition resistant, porous carbon supported multi-alloy catalyst, characterized by: The application relates to a tar catalytic cracking hydrogen production catalyst. The catalyst is supported on porous carbon, and simultaneously loaded with Ni, Co and Fe active centers, and has a pore structure with micropore and mesopore through-paths.

2. The carbon-deposition resistant, porous carbon supported multi-alloy catalyst of claim 1, wherein: The catalyst is prepared by crushing a biomass raw material, carbonizing the biomass raw material to obtain preliminary carbonized material, adding potassium carbonate to the preliminary carbonized material, and performing roasting treatment to obtain a porous carbon precursor; mixing and drying the porous carbon precursor, a nickel source, a cobalt source and an iron source, and then performing calcination reduction under a protective atmosphere to obtain the catalyst. Or; The catalyst is prepared by crushing a biomass raw material, carbonizing the biomass raw material to obtain preliminary carbonized material, adding potassium carbonate to the preliminary carbonized material, and performing roasting treatment to obtain a porous carbon precursor; mixing and drying the porous carbon precursor, a nickel source, a cobalt source and an iron source, and then performing calcination reduction under a protective atmosphere to obtain the catalyst.

3. The carbon-deposition resistant, porous carbon supported multi-alloy catalyst of claim 2, wherein: The carbonization is performed at a temperature of 350-650 DEG C for 1-4 h, and nitrogen gas with a flow rate of 80-100 mL / min is used as the protective atmosphere.

4. The carbon-deposition resistant, porous carbon-supported multi-alloy catalyst according to claim 2 or 3, characterized in that: The potassium carbonate is added in an amount of 1-4 times the mass of the preliminary carbonized material.

5. The carbon-deposition resistant, porous carbon supported multi-alloy catalyst of claim 4, wherein: The roasting treatment is performed at a temperature of 600-950 DEG C for 1-4 h, and nitrogen gas with a flow rate of 60-100 mL / min is used as the protective atmosphere.

6. The anti-carbon deposition porous carbon supported multi-alloy catalyst according to claim 2 or 5, characterized in that: The total mass ratio of the porous carbon precursor to the three metal sources, namely the nickel source, the cobalt source and the iron source, is 1:(1-10); The molar ratio of the nickel source, the cobalt source and the iron source is (3-8):(1-3):(1-2).

7. The carbon-deposition resistant, porous carbon supported multi-alloy catalyst of claim 6, wherein: The calcination reduction is performed at a temperature of 550-950 DEG C for 0.5-3 h.

8. The carbon-deposition resistant, porous carbon supported multi-alloy catalyst of claim 2, wherein: The reducing agent is at least one of sodium hypophosphite, sodium citrate and sodium borohydride, the mass ratio of the reducing agent to the porous carbon precursor is (0.5-3):1, and the reduction reaction is performed for 1-4 h.

9. The anti-coking, porous carbon supported multi-alloy catalyst of claim 1, 2, 3, 5, 7, or 8, wherein: When the catalyst is applied to tar catalytic cracking hydrogen production, the reaction temperature is 450-950 DEG C.

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