Catalyst for catalytic reforming of tar and preparation method thereof

Abstract

The invention discloses a catalyst for catalytic reforming of tar and a preparation method thereof, and the preparation method comprises the following steps: carrying out carbonization treatment on a screened biomass raw material, soaking the biomass raw material in a diluted sodium compound-containing polyvinyl chloride alkaline washing liquid for chemical activation treatment to obtain a mixture, calcining the mixture in a nitrogen atmosphere at 500-600 DEG C, and drying the calcined mixture to obtain the catalyst for catalytic reforming of tar. Cooling, washing and drying to obtain activated carbon; dipping the obtained activated carbon in a cationic surfactant for surface modification treatment, and then washing and drying to obtain modified activated carbon; the aqueous solution containing cobalt salt and the aqueous solution containing nickel salt are mixed in proportion, and a mixed metal salt solution is obtained; the modified activated carbon is added into a mixed metal salt solution for constant-temperature dipping, then filtering, drying and calcining at 700-800 DEG C are performed to obtain the metal-loaded catalyst for catalytic reforming of tar, and the biomass carbon-based catalyst has better catalytic cracking activity on tar and is beneficial to improving the carbon deposition phenomenon on the surface of the catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass and organic solid waste utilization, and particularly relates to a catalyst for catalytic reforming of tar and a preparation method thereof. Background Art

[0002] At present, the overuse of fossil energy has led to serious environmental problems globally, and the development of clean energy is imminent. Biomass resources are the largest renewable energy in the world. Biomass is considered to be the best choice to replace fossil energy due to its unique zero-carbon emission characteristics. Biomass gasification technology has been widely used due to its significant advantages in energy utilization efficiency, environmental friendliness and sustainability. However, tar is an inevitable by-product in the process of biomass gasification, which reduces the gasification efficiency and the calorific value of the fuel gas, and corrodes the pipeline. The harm of tar to the gasification efficiency and gasification equipment is the biggest obstacle that prevents the large-scale industrial application of biomass gasification technology.

[0003] Therefore, the efficient treatment of tar has become the key to the large-scale utilization of biomass gasification technology. Using a catalyst for catalytic reforming of tar to produce hydrogen requires a relatively low temperature and has a good conversion effect, which has become one of the effective means of tar treatment at present. Compared with traditional catalysts, they are expensive, have a low catalytic efficiency and a short catalyst life. Carbon-based catalysts have the characteristics of low cost and stable structure. Summary of the Invention

[0004] The present invention provides a method for preparing a high-performance carbon-based catalyst. Using biomass charcoal as a raw material, a highly efficient carbon-based catalyst loaded with metal can utilize the catalyst to catalytically reform heavy tar generated during the operation of an atmospheric fixed-bed gasifier to produce hydrogen.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a method for preparing a catalyst for catalytic reforming of tar, including the following preparation steps:

[0006] Step 1: Carbonize the screened biomass raw materials, soak them in a diluted alkaline washing solution of polyvinyl chloride containing sodium compounds for chemical activation treatment to obtain a mixture, calcine the mixture in a nitrogen atmosphere at 500°C - 600°C, then cool, wash and dry to obtain activated carbon;

[0007] Step 2: Immerse the activated carbon obtained in Step 1 in a cationic surfactant for surface modification treatment, and then wash and dry to obtain modified activated carbon;

[0008] Step 3: Add the modified activated carbon obtained in Step 2 to a metal salt solution for constant-temperature impregnation until the metal loading on the surface of the activated carbon reaches 10%, take it out for filtration, drying and calcination to obtain a catalyst for catalytic reforming of tar loaded with metal.

[0009] Furthermore, for the biomass raw material described in Step 1, raw materials with an ash content of less than 1%, an N element content of less than 0.5%, and a lignin content of more than 25% are selected; the specific surface area of the activated carbon obtained by calcination in Step 1 reaches 1000 cm 3 / g.

[0010] Furthermore, the carbonization treatment is carried out under a nitrogen atmosphere, with continuous heating at 350 °C for 30 minutes and heat preservation for 1 - 2 h to obtain biomass activated carbon.

[0011] Furthermore, the activation method described in Step 2 is chemical activation, and the activating agent is an alkaline washing solution of polyvinyl chloride, 7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl. There is a 5% C - N peak on the surface of the modified activated carbon. Furthermore, the alkaline washing solution of polyvinyl chloride is weakly alkaline.

[0012] Furthermore, the metal salt solution is an aqueous solution containing cobalt salt alone, an aqueous solution containing nickel salt, or a mixed metal salt solution of an aqueous solution containing cobalt salt and an aqueous solution containing nickel salt.

[0013] Furthermore, the cobalt salt described in Step 3 is cobalt nitrate, the nickel salt is nickel nitrate, the Co element concentration is 1 mol / L, the Ni element concentration is 1 mol / L, and the mixed molar ratio of cobalt nitrate to nickel nitrate is 1:4.

[0014] Furthermore, the surface modification treatment method is the impregnation method, the cationic surfactant is cetyltrimethylammonium bromide solution, the concentration of cetyltrimethylammonium bromide solution is 3 mmol / L, and the impregnation method is to continuously stir in a water bath oscillator at room temperature for 12 hours until it is in a completely dissolved state.

[0015] Furthermore, in Step 3, it is stirred and impregnated in a constant temperature water bath at 90 °C for 4 h; the calcination temperature described in Step 3 is 700 - 800 °C, and the calcination time is 4 - 6 h until the specific surface area of the activated carbon reaches 1000 cm 3 / g.

[0016] The present invention can also provide a catalyst for catalytic reforming of tar, which is obtained by using the above catalyst preparation method.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: The raw materials of the present invention are widely sourced and easily obtained, with good economic benefits. The present invention uses the alkaline washing solution in the preparation process of polyvinyl chloride to activate activated carbon, realizing the efficient utilization of waste. The biomass carbon - based catalyst obtained by the present invention has better catalytic cracking activity for tar, stronger catalytic ability compared with mineral - supported catalysts, further promoting the catalytic reforming reaction of tar on the catalyst surface, and lower cost. Description of the Drawings

[0018] Figure 1 This is a schematic flow chart of the method of the present invention. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The present invention first prepares a carbon carrier with high specific surface area and high porosity through low-temperature carbonization and activation with a polyvinyl chloride alkaline washing solution, then impregnates with a cetyltrimethylammonium bromide (CTAB) solution for oxidation modification to increase the number of oxygen-containing acidic groups on the surface of the carbon carrier, and finally prepares a high-performance carbon-based catalyst by loading metals.

[0021] Refer to Figure 1 , the preparation process of the high-performance carbon-based catalyst provided by the present invention is mainly divided into two stages.

[0022] The first stage is to prepare the carbon carrier. Using the widely planted coconut shell as the biomass raw material, the coconut shell is crushed into powder by a wall breaker, and the powder with a mesh size of 40-60 is screened out as the carbonized biomass raw material, and carbonization treatment is carried out in a nitrogen atmosphere using a fixed-bed heating furnace at 350 °C for 30 minutes; then a polyvinyl chloride alkaline washing solution (7.7% NaOH, 2.3% Na2CO3 and 17.1% NaCl) is configured as the activator to carry out chemical activation treatment on the carbonized coconut shell to obtain activated carbon, so as to increase the specific surface area and porosity of the biomass carbon carrier.

[0023] During preparation, the activated carbon obtained by carbonization at 350 °C is soaked in the diluted polyvinyl chloride alkali solution at a ratio of 1:7, stirred for 24 h and then put into an alumina crucible, and then transferred to a horizontal tube furnace. Nitrogen is introduced to remove air, and then the activated carbon is calcined, cooled, washed and dried at 500 °C - 600 °C.

[0024] 120 mL of 3 mmol / L cetyltrimethylammonium bromide (CTAB) solution is configured as a cationic surfactant to modify the activated carbon. The activated carbon is put into a container containing 20 mL of 3 mmol / L CTAB solution and stirred at room temperature for 12 h. Then the sample is separated, washed with deionized water until the pH is weakly alkaline, and dried at 105 °C for 12 h. The activated biomass carbon carrier has a smaller pore diameter and a more abundant pore structure than before activation, thus forming a larger pore volume inside. The chemically adsorbed capacity of the modified biomass carbon carrier is greatly improved compared with that before modification.

[0025] The second stage is the loading of metals. Cobalt is selected as the promoter of nickel for filtration, drying, and calcination in a nitrogen atmosphere at 700 °C - 800 °C using a fixed-bed heating furnace to obtain the metal-loaded carbon-based catalyst. Specifically, after preparing the biomass carbon carrier, two metals, nickel and cobalt, are selected for loading by the impregnation method, and a cobalt-nickel composite catalyst is prepared with cobalt as the promoter of nickel, and the mass ratio of cobalt to nickel is 0.25. 100 mL of 1 mol / L Ni(NO3)2 and 1 mol / L Co(NO3)2 are respectively prepared, and then Ni(NO3)2 and Co(NO3)2 are mixed in a ratio of 1:4. The modified activated carbon prepared above is added to the 100 mL mixed solution, and after stirring and impregnating in a constant-temperature water bath, it is taken out for filtration. After drying, it is calcined in a nitrogen atmosphere at 700 °C - 800 °C for 4 - 6 h to complete the preparation of the metal-loaded carbon-based catalyst.

[0026] The catalyst after loading metals has stronger catalytic activity and selectivity, which is beneficial to improving the carbon deposition phenomenon on the catalyst surface and effectively solving the problems of pipeline corrosion and blockage caused by tar.

[0027] Example 1:

[0028] Ground to 40 - 60 mesh using coconut shells, carbonized in a fixed - bed heating furnace at 350 °C under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to exclude air. Then, the mixture is calcined, cooled, washed, dried, and stored at 550 °C and marked as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as the cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and mark it as MAC. After preparing the biomass carbon carrier, select two metals, nickel and cobalt, and load them by the impregnation method. After preparing 100 mL of Ni(NO3)2 and Co(NO3)2 with a concentration of 1 mol / L, stir and impregnate it with the prepared carbon carrier in a 90 °C constant - temperature water bath for 4 h and then take it out for filtration (Ni(NO3)2:Co(NO3) = 20 mL:80 mL). After drying for 12 h, calcine it at 800 °C for 4 h to obtain MAC - Ni / Co. Adopt the cold - trapping method to collect cold - state tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to catalytically reform the tar in a quartz tube. The tube furnace is single - stage heated and has a catalyst bed layer inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas and then passes downward through the catalyst bed layer and undergoes a reforming reaction with the catalyst on the bed layer. Nitrogen and steam are respectively introduced from both sides above the quartz tube. The nitrogen flow rate is controlled by a flowmeter, and the steam first controls the water flow rate by a flow pump, enters the heating belt to be heated into steam and then enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the condition of the nickel - cobalt composite catalyst, at 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2 is the optimal working condition for catalytic reforming of tar to produce hydrogen. After catalyzing for 30 min, the hydrogen production reaches 108.62 g H2 (per 1 kg of tar).

[0029] Example Two:

[0030] Ground the coconut shell to 40 - 60 mesh, carbonize it in a fixed - bed heating furnace at 350 °C under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali liquor (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to remove air. Then calcine, cool, wash, dry, and store the mixture at 550 °C and label it as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as the cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir it in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and label it as MAC. After preparing the biomass carbon carrier, select nickel and load it by the impregnation method. Prepare 100 mL of Ni(NO3)2 with a concentration of 1 mol / L. After drying for 12 h, calcine it at 800 °C for 4 h to obtain MAC - Ni. Adopt the cold - trapping method to collect cold tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of the tar in a quartz tube. The tube furnace is single - stage heating and has a catalyst bed layer inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket filled with tar enters the tube furnace, the tar turns into gas phase and then passes downward through the catalyst bed layer and reacts with the catalyst on the bed layer for reforming. Nitrogen and steam are respectively introduced from both sides above the quartz tube. The nitrogen flow rate is controlled by a flow meter, and the steam first controls the water flow rate by a flow pump, enters the heating belt to be heated into steam and then enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the condition of the nickel - based catalyst, at 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2 for the working condition of catalytic reforming of tar to produce hydrogen, after catalyzing for 30 min, the hydrogen production reaches 76.46 g H2 (per 1 kg of tar).

[0031] Example Three:

[0032] Ground to 40 - 60 mesh using coconut shells, carbonized in a fixed - bed heating furnace at 350 °C under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to remove air. Then, the mixture is calcined at 550 °C, cooled, washed, dried, and stored, and labeled as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as a cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and label it as MAC. After preparing the biomass carbon carrier, cobalt is selected for loading using the impregnation method. Prepare 100 mL of Co(NO3)2 with a concentration of 1 mol / L. After drying for 12 h, calcine it at 800 °C for 4 h to obtain MAC - Co. Adopt the cold - trapping method to collect cold - state tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of the tar in a quartz tube. The tube furnace is single - stage heated and has a catalyst bed layer inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas and then passes downward through the catalyst bed layer and undergoes a reforming reaction with the catalyst on the bed layer. Nitrogen and steam are introduced into both sides above the quartz tube respectively. The nitrogen flow rate is controlled by a flowmeter, and the steam is first controlled by a flow pump to control the water flow rate. After entering the heating belt and being heated into steam, it enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the conditions of the cobalt - based catalyst, at 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2, for the working condition of catalytic reforming of tar to produce hydrogen, after catalyzing for 30 min, the hydrogen production reaches 88.34 g H2 (per 1 kg of tar).

[0033] Example 4:

[0034] Ground to 40 - 60 mesh using coconut shells, carbonized in a fixed - bed heating furnace at 350℃ under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to exclude air. Then calcine, cool, wash, dry, and store the mixture at 500℃ and label it as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as the cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105℃ for 12 hours, and label it as MAC. After preparing the biomass carbon carrier, select two metals, nickel and cobalt, and load them using the impregnation method. After preparing 100 mL of Ni(NO3)2 and Co(NO3)2 with a concentration of 1 mol / L, stir and impregnate with the prepared carbon carrier in a 90℃ constant - temperature water bath for 4 h and then take it out for filtration (Ni(NO3)2:Co(NO3) = 20 mL:80 mL). After drying for 12 h, calcine at 800℃ for 4 h to obtain MAC - Ni / Co. Adopt the cold - trapping method to collect cold - state tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of the tar in a quartz tube. The tube furnace is single - stage heating and is equipped with a catalyst bed inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas and then passes downward through the catalyst bed and undergoes a reforming reaction with the catalyst on the bed. Nitrogen and steam are respectively introduced from both sides above the quartz tube. The nitrogen flow rate is controlled by a flow meter, and the steam first controls the water flow rate by a flow pump, enters the heating belt to be heated into steam and then enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the condition of the nickel - cobalt composite catalyst, 800℃, m Steam / m Tar =3, m Tar / m Catalyst =2 is the optimal condition for tar catalytic reforming to produce hydrogen. After catalyzing for 30 min, the hydrogen production reaches 97.43 g H2 (per 1 kg of tar).

[0035] Example 5:

[0036] Ground to 40 - 60 mesh using coconut shells, carbonized in a fixed - bed heating furnace at 350 °C under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to exclude air. Then the mixture is calcined, cooled, washed, dried, and stored at 600 °C and labeled as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as the cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and label it as MAC. After preparing the biomass carbon carrier, select two metals, nickel and cobalt, and load them using the impregnation method. After preparing 100 mL of Ni(NO3)2 and Co(NO3)2 with a concentration of 1 mol / L, stir and impregnate with the prepared carbon carrier in a constant - temperature water bath at 90 °C for 4 h and then take it out for filtration (Ni(NO3)2:Co(NO3)=20 mL:80 mL). After drying for 12 h, calcine at 800 °C for 4 h to obtain MAC - Ni / Co. Adopt the cold - trapping method to collect cold tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of tar in a quartz tube. The tube furnace is single - stage heating and is provided with a catalyst bed inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas phase and then passes downward through the catalyst bed and undergoes a reforming reaction with the catalyst on the bed. Nitrogen (N2) and steam are respectively introduced from both sides above the quartz tube. The nitrogen flow rate is controlled by a flow meter, and the steam is first controlled by a flow pump for the water flow rate, enters the heating belt to be heated into steam and then enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the condition of the nickel - cobalt composite catalyst, 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2 is the best working condition for hydrogen production by catalytic reforming of tar. After 30 minutes of catalysis, the hydrogen production reaches 94.21 g H2 (per 1 kg of tar).

[0037] Example Six:

[0038] Ground to 40 - 60 mesh using coconut shells, carbonized in a fixed - bed heating furnace at 350 °C under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to exclude air. Then, the mixture is calcined, cooled, washed, dried, and stored at 550 °C and labeled as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as the cationic surfactant. Put 1 g of unprocessed AC into a 100 - mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water - bath oscillator at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and label it as MAC. After preparing the biomass carbon carrier, select two metals, nickel and cobalt, and load them using the impregnation method. After preparing 100 mL of Ni(NO3)2 and Co(NO3)2 with a concentration of 1 mol / L, stir and impregnate with the prepared carbon carrier in a constant - temperature water bath at 90 °C for 4 h and then take it out for filtration (Ni(NO3)2:Co(NO3)=20 mL:80 mL). After drying for 12 h, calcine at 700 °C for 4 h to obtain MAC - Ni / Co. Adopt the cold - trapping method to collect cold tar at the tar outlet position of a certain atmospheric - pressure fixed - bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of tar in a quartz tube. The tube furnace is single - stage heated and has a catalyst bed layer inside. Set a hanging basket in the quartz tube of the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas phase and then passes downward through the catalyst bed layer and undergoes a reforming reaction with the catalyst on the bed layer. Nitrogen and steam are respectively introduced from both sides above the quartz tube. The nitrogen flow rate is controlled by a flow meter, and the steam is first controlled by a flow pump to control the water flow rate. After entering the heating belt and being heated into steam, it enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the condition of the nickel - cobalt composite catalyst, 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2 is the optimal working condition for hydrogen production by catalytic reforming of tar. After 30 min of catalysis, the hydrogen production reaches 79.86 g H2 (per 1 kg of tar).

[0039] Example Seven:

[0040] Ground to 40-60 mesh using coconut shells, carbonized at 350 °C in a fixed-bed heating furnace under a nitrogen atmosphere for 30 minutes. Select 20 g and soak it in diluted polyvinyl chloride waste alkali solution (7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl) at a ratio of 1:7, stir for 24 hours, then put it into an alumina crucible and transfer it to a horizontal tube furnace. Nitrogen (N2) enters the system at a flow rate of 400 mL / min to remove air. Then the mixture is calcined, cooled, washed, dried, and stored at 550 °C and marked as AC. Use cetyltrimethylammonium bromide (abbreviated as CTAB) as a cationic surfactant. Put 1 g of unprocessed AC into a 100 mL conical flask containing 20 mL of 3 mmol / L CTAB solution, stir in a water bath shaker at room temperature for 12 hours. Then separate the sample, wash it with deionized water, and dry it at 105 °C for 12 hours, and mark it as MAC. After preparing the biomass carbon carrier, select two metals, nickel and cobalt, and load them by the impregnation method. After preparing 100 mL of Ni(NO3)2 and Co(NO3)2 with a concentration of 1 mol / L, stir and impregnate with the prepared carbon carrier in a 90 °C constant temperature water bath for 4 h and then take it out for filtration (Ni(NO3)2:Co(NO3) = 20 mL:80 mL). After drying for 12 h, calcine at 750 °C for 4 h to obtain MAC-Ni / Co. Adopt the cold trapping method to collect cold tar at the tar outlet position of a certain atmospheric fixed-bed straw gasifier. Use a vertical tube furnace to carry out catalytic reforming of tar in a quartz tube. The tube furnace is single-stage heating and is provided with a catalyst bed inside. A hanging basket is arranged in the quartz tube in the heating furnace. After the hanging basket containing tar enters the tube furnace, the tar turns into gas and then passes downward through the catalyst bed and undergoes a reforming reaction with the catalyst on the bed. Nitrogen and steam are respectively introduced into both sides above the quartz tube. The nitrogen flow rate is controlled by a flow meter, and the steam first controls the water flow rate by a flow pump, enters the heating belt to be heated into steam and then enters the quartz tube to participate in the catalytic reforming reaction. The results show that under the conditions of the nickel-cobalt composite catalyst, 800 °C, m Steam / m Tar =3, m Tar / m Catalyst =2 is the optimal working condition for hydrogen production by catalytic reforming of tar. After catalyzing for 30 min, the hydrogen production reaches 81.22 g H2 (per 1 kg of tar).

[0041] The above is only a preferred specific embodiment of the present invention; however, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its improved concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for catalytic reforming of tar, characterized in that, It includes the following preparation steps: Step 1: Carbonize the sieved biomass raw materials, soak them in a diluted alkaline polyvinyl chloride washing solution containing sodium compounds for chemical activation treatment to obtain a mixture, calcine the mixture in a nitrogen atmosphere at 500°C - 600°C, then cool, wash, and dry to obtain activated carbon; Step 2: Immerse the activated carbon obtained in Step 1 in a cationic surfactant for surface modification treatment, then wash and dry to obtain modified activated carbon; Step 3: Add the modified activated carbon obtained in Step 2 to a metal salt solution for constant-temperature impregnation until the metal loading on the surface of the activated carbon reaches 10%, take it out for filtration, drying, and calcination to obtain a catalyst for catalytic reforming of tar loaded with metal.

2. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, wherein, The biomass raw materials described in Step 1 are raw materials with an ash content of less than 1%, an N element content of less than 0.5%, and a lignin content of more than 25%.

3. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, characterized in that, The carbonization treatment is carried out under a nitrogen atmosphere, with continuous heating at 350 °C for 30 minutes and heat preservation for 1 - 2 h to obtain biomass activated carbon; the specific surface area of the activated carbon obtained by calcination in step 1 reaches 1000 cm 3 / g.

4. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, wherein The activation method described in Step 2 is chemical activation, the activator is an alkaline polyvinyl chloride washing solution, 7.7% NaOH, 2.3% Na2CO3, and 17.1% NaCl, and there is a 5% C-N peak on the surface of the modified activated carbon.

5. The method for preparing a catalyst for catalytic reforming of tar according to claim 4, characterized in that, The alkaline polyvinyl chloride washing solution is weakly alkaline.

6. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, characterized in that, The metal salt solution is an aqueous solution containing only cobalt salt, an aqueous solution containing only nickel salt, or a mixed metal salt solution of an aqueous solution containing cobalt salt and an aqueous solution containing nickel salt.

7. The method for preparing a catalyst for catalytic reforming of tar according to claim 6, wherein The cobalt salt described in Step 3 is cobalt nitrate, the nickel salt is nickel nitrate, the Co element concentration is 1 mol / L, the Ni element concentration is 1 mol / L, and the mixed molar ratio of cobalt nitrate to nickel nitrate is 1:

4.

8. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, wherein The surface modification treatment method is the impregnation method, the cationic surfactant is cetyltrimethylammonium bromide solution, the concentration of cetyltrimethylammonium bromide solution is 3 mmol / L, and the impregnation method is to continuously stir in a water bath oscillator at room temperature for 12 hours until it is in a completely dissolved state.

9. The method for preparing a catalyst for catalytic reforming of tar according to claim 1, characterized in that, Step 3 Stir and impregnate in a constant temperature water bath at 90 °C for 4 h; the calcination temperature described in Step 3 is 700-800 °C, and the calcination time is 4-6 h until the specific surface area of the activated carbon reaches 1000 cm 3 / g.

10. A catalyst for catalytic reforming of tar, characterized in that, It is obtained by using the catalyst preparation method described in any one of Claims 1 - 9.

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