Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a carrier and a catalyst for integral tar cracking and a preparation method thereof. The catalyst has the advantages of reduced pressure, adjustable porosity, large specific surface area, high activity, high microwave absorption rate, good thermal shock resistance, strong water resistance at high temperature, sintering resistance, carbon deposition resistance and long-term and efficient use. Solves the problem that the prior tar cracking catalyst can not simultaneously consider the performances of high temperature stability, water resistance, high specific surface area, high loading capacity, sintering resistance, carbon deposition resistance and the like.
The invention provides a preparation method of a carrier for integral tar cracking, which comprises the following steps:
(1) mixing the carbon precursor, the activating agent and the aid A solution, and uniformly mixing to obtain slurry A;
(2) adding polyurethane foam into the slurry A for dipping, and then roasting and washing to obtain a carbon template;
(3) mixing a silicon source and the aid B solution, and regulating and controlling the pH value of the system to be 1-10 to obtain slurry B;
(4) and (3) adding the carbon template obtained in the step (2) into the slurry B for dipping, adding a sample obtained after the dipping is finished and the roasting into a hydrofluoric acid solution for treatment, and further washing to obtain the carrier.
In the preparation method of the integral tar cracking carrier, the carbon precursor in the step (1) may be one or more of phenolic resin, starch, dextrin, glycerol and water-soluble polysaccharide, preferably phenolic resin and/or starch, and more preferably water-soluble phenolic resin.
In the preparation method of the carrier for integral tar cracking, the activating agent in the step (1) is one or more of potassium hydroxide, sodium hydroxide, potassium carbonate, zinc chloride and phosphoric acid, and potassium hydroxide is preferred.
In the preparation method of the carrier for integral tar cracking, the assistant A solution in the step (1) comprises an assistant A, a solvent and water, wherein the assistant A is one or more of tetramethylammonium hydroxide, polyethylene glycol (molecular weight 200-. The solvent is an organic solvent, preferably an alcohol solvent, and specifically may be one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butanediol, and more preferably ethanol. Based on the mass of the assistant solution, the mass concentration of the assistant A is 0.1wt% -10 wt%, and the mass concentration of the solvent is 0.1wt% -80 wt%.
In the preparation method of the integral type carrier for tar cracking, the mixing temperature in the step (1) is 20-80 ℃. Based on the dry basis weight of the activating agent, the dry basis content of the assistant A is 1wt% -10 wt%; the mass ratio of the activating agent to the carbon precursor is 0.2-5: 1.
In the preparation method of the integral tar cracking carrier, in the step (2), the polyurethane foam is flexible polyurethane foam with mutually-communicated pores, and the pore size of the flexible polyurethane foam is 5-200 ppi (pore per inch). Further preferably, the polyurethane foam in step (2) of the present invention may be obtained by modifying an existing polyurethane foam material, wherein the modification is obtained by soaking the polyurethane foam material in an acid or alkali solution, and then washing the polyurethane foam material. The acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid and citric acid, and the mass concentration of the acid is 1-20 wt%; the alkali can be one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide, the mass concentration of the alkali is 1wt% -20 wt%, and the soaking time is 1-10 hours. The washing is carried out for 2-6 times by using deionized water, and the washing is further preferably carried out under the ultrasonic condition.
In the preparation method of the integral type carrier for tar cracking, in the step (2), the roasting temperature is 350-900 ℃, the roasting time is 2-10 hours, the roasting is carried out in the presence of nitrogen or inert gas, and the inert gas is one or more of helium, neon, argon, krypton and xenon.
In the preparation method of the carrier for integral tar cracking, the washing in the step (2) is carried out by using an acid solution or deionized water until no activator ion is detected, the acid can be one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, oxalic acid and citric acid, the mass concentration of the acid solution is 1-20 wt%, and the washing temperature is 20-80 ℃.
In the preparation method of the carrier for integral tar cracking, the impregnation step in the step (2) is as follows: and (3) soaking the polyurethane foam into the slurry A, taking out, draining, drying in a vacuum dryer at the temperature of 60-150 ℃, taking out after 5-35 min, and repeating the process for 5-10 times.
In the preparation method of the integral type carrier for tar cracking, the silicon source in the step (3) is one or more of sodium silicate, methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate and isopropyl orthosilicate; preferably sodium silicate and/or ethyl orthosilicate.
In the preparation method of the carrier for integral tar cracking, the assistant B solution in the step (3) comprises an assistant B, a solvent and water, wherein the assistant B is one or more of carboxymethyl cellulose, hydroxyethyl cellulose, microcrystalline cellulose, chitosan, sesbania powder, hydroxypropyl methyl cellulose, polyvinyl alcohol (molecular weight of 5000-; the solvent is an organic solvent, preferably an alcohol solvent, and specifically may be one or more of ethanol, methanol, propanol, butanol, ethylene glycol, propylene glycol, glycerol, and butanediol, and more preferably ethanol. Based on the mass of the solution of the assistant B, the mass concentration of the assistant B is 0.1wt% -20 wt%, and the mass concentration of the solvent is 0.1wt% -80 wt%.
In the preparation method of the carrier for integral tar cracking, the pH value of the regulation and control system in the step (3) is 1-10, and the pH value can be regulated by adding acid or ammonia water, wherein the acid can be one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid and citric acid.
In the preparation method of the integral type carrier for tar cracking, the mixing temperature in the step (3) is 20-120 ℃. Based on the dry basis mass of the silicon source, the dry basis content of the auxiliary B is 1wt% -10 wt%.
In the preparation method of the integral type carrier for tar cracking, the impregnation step in the step (4) is as follows: and (3) immersing the carbon template obtained in the step (2) into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying in a vacuum dryer at the temperature of 60-150 ℃, taking out after 5-35 min, and repeating the process for 5-10 times.
In the preparation method of the integral type carrier for tar cracking, in the step (4), the roasting temperature is 1200-1900 ℃; the roasting time is 3-24 hours, preferably 7-15 hours, the roasting is further preferably carried out in the presence of nitrogen or inert gas, and the inert gas is one or more of helium, neon, argon, krypton and xenon. The calcination is further preferably conducted under microwave conditions.
In the preparation method of the carrier for integral tar cracking, the concentration of the hydrofluoric acid solution in the step (4) is 20-40 wt%, and the treatment time is 5-12 hours.
In the preparation method of the carrier for integral tar cracking, the washing in the step (4) is washing with deionized water for 2-6 times, and the washing is further preferably carried out under an ultrasonic condition.
The second aspect of the invention provides a preparation method of a second integral type carrier for tar cracking, which further comprises a step (5) of carrying out high-temperature treatment on the carrier obtained in the step (4) in the presence of oxygen-containing gas, mixing the treated material with alkaline solution or hydrofluoric acid solution for treatment, and then washing, drying and roasting the mixture to obtain the carrier.
In the preparation method of the integral type carrier for tar cracking, the high-temperature treatment temperature in the step (5) is 800-1300 ℃, preferably 950-1300 ℃, further preferably 1000-1300 ℃, and the treatment time is 0.5-8 hours, preferably 4-6 hours.
In the preparation method of the integral type carrier for cracking tar, in the step (5), the oxygen-containing atmosphere can be any one of air, oxygen, a mixed gas of oxygen and nitrogen and a mixed gas of oxygen and inert gas, wherein the volume content of oxygen in the mixed gas is 5-100%; the inert gas is one or more of helium, neon, argon, krypton and xenon.
In the preparation method of the integral tar cracking carrier, the alkaline solution in the step (5) is an inorganic alkaline solution, and may be one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide, preferably sodium hydroxide and/or potassium hydroxide, and more preferably sodium hydroxide.
In the preparation method of the integral type carrier for tar cracking, the mass ratio of the material obtained after the high-temperature treatment in the step (5) to the alkaline solution or the hydrofluoric acid solution is 1: 80-1: 10, the concentration of the alkaline solution is 0.1-20 wt%, and the concentration of the hydrofluoric acid solution is 0.01-5 wt%.
In the preparation method of the integral type carrier for tar cracking, the mixing treatment temperature in the step (5) is 60-120 ℃, and the treatment time is 0.5-5 hours.
In the preparation method of the carrier for integral tar cracking, the washing in the step (5) is washing with deionized water for 2-6 times, and the washing is further preferably carried out under an ultrasonic condition. In the step (5), the drying temperature is 100-150 ℃, and the drying is preferably carried out under the microwave condition; in the step (5), the roasting temperature is 650-1000 ℃, the roasting time is 3-9 hours, the roasting is preferably carried out under the condition of nitrogen or inert gas, and the roasting is further preferably carried out under the condition of microwave.
In the third aspect of the present invention, there is provided a third method for preparing a carrier for cracking integral tar, the method further preferably includes a step (6) of adding the carrier obtained in the step (5) into a carbon-containing precursor solution for impregnation, and then drying and roasting the impregnated carrier, wherein the roasting is performed in a nitrogen atmosphere.
In the preparation method of the carrier for integral tar cracking, the carbon-containing precursor in the step (6) is one or more of monosaccharide, disaccharide, water-soluble polysaccharide, phenolic resin, starch, dextrin and glycerol, and preferably sucrose and/or phenolic resin.
In the preparation method of the integral type carrier for tar cracking, the mass fraction of the carbon-containing precursor solution in the step (6) is 1-25%, and the dipping temperature in the step (6) is 20-90 ℃.
In the preparation method of the carrier for integral tar cracking, the drying temperature in the step (6) is 100-150 ℃, and preferably, the drying is carried out under the microwave condition.
In the preparation method of the integral type carrier for tar cracking, in the step (6), the roasting temperature is 1000-1600 ℃, preferably 1100-1500 ℃, the treatment time is 0.5-4 hours, and further preferably roasting under the microwave condition.
The invention provides a carrier for cracking integral tar, which is obtained by the first preparation method and is foam silicon carbide.
The fifth aspect of the invention provides a carrier for cracking integral tar, wherein the carrier is obtained by adopting the second preparation method. The carrier is modified foam silicon carbide, and the modified foam silicon carbide comprises foam silicon carbide and silicon oxide dispersed on the surface of the foam silicon carbide.
The sixth aspect of the invention provides a carrier for integral tar cracking, wherein the carrier is obtained by adopting the third preparation method. The carrier is modified foam silicon carbide, and the modified foam silicon carbide comprises foam silicon carbide and silicon oxide and silicon nitride which are dispersed on the surface of the foam silicon carbide.
The seventh aspect of the present invention provides a monolithic tar cracking catalyst, which comprises a carrier and an active metal component, wherein the carrier of the catalyst adopts the carrier provided by the fourth aspect.
In the integral tar cracking catalyst, the weight of the catalyst is taken as a reference, the content of the carrier is 60-99%, preferably 80-98 wt%, and the content of the active metal component is 1-40 wt%, preferably 2-20 wt%.
The specific properties of the monolithic tar cracking catalyst are as follows: the specific surface area is 55-600m2The pore volume is more than 0.01 mL/g.
The eighth aspect of the invention provides an integral tar cracking catalyst, which comprises a carrier and an active metal component, wherein the carrier of the catalyst adopts the carrier provided by the fifth aspect.
In the integral tar cracking catalyst, the weight of the catalyst is taken as a reference, the content of the carrier is 60-99%, preferably 80-98 wt%, and the content of the active metal component is 1-40 wt%, preferably 2-20 wt%.
The specific properties of the monolithic tar cracking catalyst are as follows: the specific surface area is 55-600m2The pore volume is more than 0.01 mL/g.
The ninth aspect of the invention provides an integral tar cracking catalyst, which comprises a carrier and an active metal component, wherein the carrier of the catalyst is the carrier provided by the sixth aspect.
In the integral tar cracking catalyst, the weight of the catalyst is taken as a reference, the content of the carrier is 60-99%, preferably 80-98 wt%, and the content of the active metal component is 1-40 wt%, preferably 2-20 wt%.
The specific properties of the monolithic tar cracking catalyst are as follows: the specific surface area is 55-600m2The pore volume is more than 0.01 mL/g.
In the three tar cracking catalysts, the active metal component is the third
Group metal, group III
Group B metals, group III
One or more of B group metals, wherein VIII group metals are one or more of iron, nickel, cobalt and palladium, and
the B group metal is one or more of chromium, molybdenum and tungsten
The B group metal is one or more of manganese and rhenium; the active metal component is further preferably iron and/or nickel.
In the integral tar cracking catalyst, the catalyst also comprises an auxiliary agent, wherein the auxiliary agent is one or more of compounds containing magnesium, strontium, cerium, zirconium, lanthanum, ytterbium and copper. The content of the auxiliary agent is 0.01-1% by weight of the catalyst.
The tenth aspect of the present invention provides a preparation method of the monolithic tar cracking catalyst, wherein the preparation method comprises the following steps: and adding the prepared carrier into an impregnation solution, and drying and roasting after impregnation to obtain the catalyst.
In the preparation method of the integral tar cracking catalyst, the ingredient of the impregnating solution is
Group metal salt solution, 1
Solution of group B metal salt
One or more of B group metal salt solution, preferably iron salt and/or nickel salt; wherein the ferric salt is one or more of ferric nitrate, ferrous acetate, ferrous nitrate and ferric acetylacetonate, and is further preferably ferric nitrate and/or ferrous acetate; the nickel salt is one or more of nickel chloride, nickel nitrate, nickel acetate and nickel acetylacetonate, and is preferably nickel nitrate and/or nickel acetate. The pH value of the impregnation liquid is 1-10, the pH value of the impregnation liquid can be adjusted by acid, and the impregnation liquid can be one or more of nitric acid, hydrochloric acid, phosphoric acid, oxalic acid and citric acid.
In the preparation method of the integral tar cracking catalyst, the impregnation liquid can also contain an auxiliary agent precursor, and the auxiliary agent precursor can be one or more of magnesium acetate, strontium nitrate, cerium nitrate, zirconyl nitrate, lanthanum nitrate, ytterbium nitrate and copper nitrate.
In the preparation method of the integral tar cracking catalyst, the dipping temperature is normal temperature to 90 ℃.
In the preparation method of the integral tar cracking catalyst, the drying temperature is 100-150 ℃, and the drying is preferably carried out under the microwave condition; the roasting temperature is 650-1000 ℃, the roasting time is 3-9 hours, the roasting is preferably carried out under the condition of nitrogen or inert gas, and the roasting is further preferably carried out under the condition of microwave.
Compared with the prior art, the carrier and the catalyst for cracking the integral tar and the preparation method thereof have the following advantages:
1. the catalyst for cracking the integral tar takes the modified foam silicon carbide material as a carrier, and the carrier has good chemical stability, thermal stability, strength and heat conduction and electric conductivity. The integral tar cracking catalyst obtained by loading metal on the carrier has stable performance in the high-temperature environment of tar cracking reaction, and has higher catalyst activity and longer catalyst service life.
2. The preparation method of the integral type carrier for tar cracking, provided by the invention, comprises the steps of preparing a high specific surface area carbon-deposited template by using an organic template impregnation process for in-situ pyrolysis and carbonization under the action of an activating agent, and then preparing a high specific surface area foam silicon carbide carrier by using a template method taking high specific surface area foam carbon as a template, wherein the specific surface area of the carrier can be controlled by different pyrolysis and carbonization conditions. The high specific surface area of the foam silicon carbide improves the metal loading capacity, so that the catalyst has higher catalytic cracking tar activity. Meanwhile, the drying and sintering treatment under the microwave condition solves the problem that the carrier structure is easy to deform and collapse caused by uneven sintering under the condition of low auxiliary agent, and ensures that the foam silicon carbide carrier with high specific surface area has higher mechanical strength.
3. The carrier for cracking the integral tar has uniform pores, the appearance and the porosity can be regulated and controlled by selecting polyurethane foams with different shapes and pore diameters, and the modified foam silicon carbide material has good permeability, so that the pressure drop of a bed layer is low, the probability of channeling is reduced, the utilization rate of a catalyst is improved, and the carrier can tolerate high-flux gas treatment reaction with higher solid particle content. Meanwhile, the modified foam silicon carbide material has a three-dimensional network open-cell structure which is communicated with each other, the continuity of the structure is favorable for exerting the advantages of high thermal conductivity and high far infrared radiation rate of the silicon carbide, the reaction heat can be effectively transferred in the catalytic reaction process, and the modified foam silicon carbide material is suitable for the strong heat absorption reaction of tar cracking. And the modified foam silicon carbide material has strong microwave absorption capacity because the microwave can be continuously absorbed, reflected and lost in the three-dimensional network structure.
4. According to the preparation method of the carrier for integral tar cracking, the foam silicon carbide is modified, so that the problems that the bonding force between the active metal and the carrier is weak, the active metal is easy to agglomerate and even fall off and the like caused by the chemical inertia of the silicon carbide are solved. The surface of the carrier is treated by high-temperature oxidation atmosphere to form a controllable extremely thin oxide layer, so that the acting force between the carrier and the active metal component can be effectively improved, and the stability of the active metal is ensured. The high-temperature nitriding atmosphere treatment in another embodiment forms weak alkaline centers taking silicon nitride as a main component on the surface of the carrier, and contributes to improving the carbon deposition resistance and the catalytic activity of the catalyst, so that the catalyst has longer service life.
Detailed Description
The following examples are provided to further illustrate the details and effects of the method of the present invention, but are not intended to limit the scope of the invention.
Example 1
Slowly dissolving water-soluble phenolic resin, potassium hydroxide, polyethylene glycol (molecular weight is 400) and carboxymethyl cellulose in deionized water containing 30wt% of ethanol at 25 ℃ under stirring to obtain slurry A. Wherein, based on potassium hydroxide, the content of polyethylene glycol (molecular weight is 400) is 1wt%, the content of carboxymethyl cellulose is 1.5wt%, and the mass ratio of potassium hydroxide to water-soluble phenolic resin is 1: 1.
Selecting a soft polyurethane foam with a pore size of 50 ppi (pore per inch) and mutually communicated pores as a template, firstly cutting the foam into a certain shape, then soaking the foam in a 10wt% NaOH solution for 5 hours, finally placing the foam in deionized water for ultrasonic treatment for 5min, then washing the foam with the deionized water, and repeating the steps for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 120 ℃ in a vacuum dryer, taking out after 35min, repeating the process for 5 times, keeping the temperature at 600 ℃ for 3 hours in a nitrogen atmosphere, cooling, and washing with a 5wt% hydrochloric acid solution at 25 ℃ until no activator ion is detected, thereby obtaining the carbon template.
Sesbania powder and polyvinyl alcohol (average molecular weight is 22000) are dissolved in deionized water containing 25wt% of ethanol, the pH value is adjusted to 3 by oxalic acid, and tetraethoxysilane is slowly added under stirring at 60 ℃ to slowly make the solution become slurry, so that slurry B is obtained. Wherein, the sesbania powder content is 5wt% and the polyvinyl alcohol content is 1wt% based on the weight of the tetraethoxysilane. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 120 ℃ in a vacuum drier, taking out after 35min, and repeating the process for 5 times. And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the dried carrier constant at 1700 ℃ for 15 hours in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times.
The carrier prepared above is put into the impregnation liquid, and the impregnation temperature is 80 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate and lanthanum nitrate, and the pH value is adjusted to 3 by nitric acid. Based on the weight of the catalyst, the iron content was 8%, the nickel content was 2%, and the lanthanum content was 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave baking oven, and keeping the temperature of the microwave baking oven at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 2
Glycerol, potassium hydroxide and carboxymethyl cellulose were slowly dissolved in deionized water containing 0.1wt% ethanol at 120 ℃ with stirring to give slurry A. Wherein, based on potassium hydroxide, the content of the carboxymethyl cellulose is 1wt%, and the mass ratio of the potassium hydroxide to the glycerol is 0.2: 1.
Selecting flexible polyurethane foam with pore size of 5ppi (pore per inch) and mutually communicated pores as a template, cutting into a certain shape, soaking in 1wt% KOH solution for 1 hour, finally placing in deionized water for ultrasonic treatment for 5min, then cleaning with deionized water, and repeating for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying in a vacuum dryer at 150 ℃, taking out after 5min, repeating the process for 10 times, keeping the temperature of 900 ℃ in a nitrogen atmosphere for 2 hours, cooling, and washing with 1wt% hydrochloric acid solution at 25 ℃ until no activator ion is detected, thus obtaining the carbon template.
Hydroxypropyl methylcellulose, polyvinyl alcohol (average molecular weight 22000) were dissolved in deionized water containing 10wt% ethanol, and the pH was adjusted to 5 with citric acid, and isopropyl n-silicate was slowly added under stirring at 80 ℃ to slowly make the solution into a slurry, to obtain slurry B. Wherein, based on the mass of the isopropyl n-silicate, the content of the hydroxypropyl methyl cellulose is 0.5 weight percent, and the content of the polyvinyl alcohol is 0.2 weight percent. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying in a vacuum drier at 100 ℃, taking out after 35min, and repeating the process for 10 times. And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the dried carrier constant for 15 hours at 1900 ℃ in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times.
The carrier prepared above is put into the impregnation liquid, and the impregnation temperature is 80 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate and chromium nitrate, and the pH value is adjusted to 5 by nitric acid. Based on the weight of the catalyst, the content of iron is 0.5%, the content of nickel is 1.5%, and the content of chromium is 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave baking oven, and keeping the temperature of the microwave baking oven at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 3
Slowly dissolving water-soluble phenolic resin, potassium hydroxide, polyethylene glycol (molecular weight is 400) and carboxymethyl cellulose in deionized water containing 30wt% of ethanol at 25 ℃ under stirring to obtain slurry A. Wherein, based on potassium hydroxide, the content of polyethylene glycol (molecular weight is 400) is 1wt%, the content of carboxymethyl cellulose is 1.5wt%, and the mass ratio of potassium hydroxide to water-soluble phenolic resin is 1: 1.
Selecting a soft polyurethane foam with a pore size of 50 ppi (pore per inch) and mutually communicated pores as a template, firstly cutting the foam into a certain shape, then soaking the foam in a 10wt% NaOH solution for 5 hours, finally placing the foam in deionized water for ultrasonic treatment for 5min, then washing the foam with the deionized water, and repeating the steps for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 120 ℃ in a vacuum dryer, taking out after 35min, repeating the process for 5 times, keeping the temperature at 600 ℃ for 3 hours in a nitrogen atmosphere, cooling, and washing with a 5wt% hydrochloric acid solution at 25 ℃ until no activator ion is detected, thereby obtaining the carbon template.
Sesbania powder and polyvinyl alcohol (average molecular weight is 22000) are dissolved in deionized water containing 25wt% of ethanol, the pH value is adjusted to 3 by oxalic acid, and tetraethoxysilane is slowly added under stirring at 60 ℃ to enable the solution to become slurry slowly, so that slurry B is obtained. Wherein, the sesbania powder content is 5wt% and the polyvinyl alcohol content is 1wt% based on the weight of the tetraethoxysilane. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 120 ℃ in a vacuum drier, taking out after 35min, and repeating the process for 5 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the dried carrier constant at 1700 ℃ for 15 hours in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The carrier is put into a microwave roasting oven and is kept at the constant temperature of 1300 ℃ for 4 hours in the oxygen atmosphere. Cooling, adding into 2wt% NaOH solution, slowly heating to 120 deg.C, treating for 2 hr, cooling, placing in deionized water, ultrasonic treating for 5min, cleaning with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and calcining at 800 deg.C for 3 hr.
The carrier prepared above is put into the impregnation liquid, and the impregnation temperature is 80 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate and lanthanum nitrate, and the pH value is adjusted to 3 by nitric acid. Based on the weight of the catalyst, the iron content was 8%, the nickel content was 2%, and the lanthanum content was 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 4
Phenolic resin, zinc chloride, polyethylene glycol (molecular weight is 4000) and tetramethylammonium hydroxide are slowly dissolved in deionized water containing 80wt% of ethanol at 60 ℃ under stirring to obtain slurry A. Wherein, based on zinc chloride, the content of polyethylene glycol (with molecular weight of 4000) is 5wt%, the content of tetramethyl ammonium hydroxide is 0.5wt%, and the mass ratio of zinc chloride to phenolic resin is 0.5: 1.
Selecting a soft polyurethane foam with a pore size of 20 ppi (pore per inch) and mutually communicated pores as a template, cutting into a certain shape, soaking in 10wt% hydrochloric acid solution for 1 hour, finally placing in deionized water for ultrasonic treatment for 5min, then cleaning with deionized water, and repeating for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 120 ℃ in a vacuum dryer, taking out after 25min, repeating the process for 7 times, keeping the temperature at 350 ℃ in a nitrogen atmosphere for 10 hours, cooling, and washing with a 20wt% hydrochloric acid solution at 85 ℃ until no activator ion is detected, thus obtaining the carbon template.
Dissolving sesbania powder and silicone oil in deionized water containing 5wt% of ethanol, adjusting the pH value to 1 by using phosphoric acid, and slowly adding methyl orthosilicate under the stirring at normal temperature to slowly turn the solution into slurry to obtain slurry B. Wherein, based on the mass of the methyl orthosilicate, the sesbania powder content is 9wt%, and the silicone oil content is 0.5 wt%. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 120 ℃ in a vacuum drier, taking out after 15min, and repeating the process for 8 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the carrier constant at 1200 ℃ for 7 hours in an argon atmosphere, soaking the carrier in 40wt% hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The carrier is sent into a microwave roasting oven and is kept at the constant temperature of 800 ℃ for 8 hours in the air atmosphere. Cooling, treating in 0.5wt% hydrofluoric acid solution for 2 hr, ultrasonic treating in deionized water for 5min, washing with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and calcining at 800 deg.C for 3 hr.
The carrier prepared above was put into the impregnation solution at an impregnation temperature of 90 ℃. The impregnation liquid contains ferric acetate and nickel nitrate, and the pH value is adjusted to 3 by citric acid. Based on the weight of the catalyst, the iron content was 12% and the nickel content was 3%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 5
Slowly dissolving water-soluble phenolic resin, potassium hydroxide, polyethylene glycol (molecular weight is 400) and carboxymethyl cellulose in deionized water containing 30wt% of ethanol at 25 ℃ under stirring to obtain slurry A. Wherein, based on potassium hydroxide, the content of polyethylene glycol (molecular weight is 400) is 1wt%, the content of carboxymethyl cellulose is 1.5wt%, and the mass ratio of potassium hydroxide to water-soluble phenolic resin is 1: 1.
Selecting a soft polyurethane foam with a pore size of 50 ppi (pore per inch) and mutually communicated pores as a template, firstly cutting the foam into a certain shape, then soaking the foam in a 10wt% NaOH solution for 5 hours, finally placing the foam in deionized water for ultrasonic treatment for 5min, then washing the foam with the deionized water, and repeating the steps for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 120 ℃ in a vacuum dryer, taking out after 35min, repeating the process for 5 times, keeping the temperature at 600 ℃ for 3 hours in a nitrogen atmosphere, cooling, and washing with a 5wt% hydrochloric acid solution at 25 ℃ until no activator ion is detected, thereby obtaining the carbon template.
Sesbania powder and polyvinyl alcohol (average molecular weight is 22000) are dissolved in deionized water containing 25wt% of ethanol, the pH value is adjusted to 3 by oxalic acid, and tetraethoxysilane is slowly added under stirring at 60 ℃ to slowly make the solution become slurry, so that slurry B is obtained. Wherein, the sesbania powder content is 5wt% and the polyvinyl alcohol content is 1wt% based on the weight of the tetraethoxysilane. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 120 ℃ in a vacuum drier, taking out after 35min, and repeating the process for 5 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the dried carrier constant at 1700 ℃ for 15 hours in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The carrier is put into a microwave roasting oven and is kept at the constant temperature of 1300 ℃ for 4 hours in the oxygen atmosphere. Cooling, adding into 2wt% NaOH solution, slowly heating to 120 deg.C, treating for 2 hr, cooling, placing in deionized water, ultrasonic treating for 5min, cleaning with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and calcining at 800 deg.C for 3 hr. Then the carrier is put into an impregnation liquid containing 5 percent of cane sugar, is impregnated at normal temperature, is dried at 120 ℃ after being impregnated, and is sent into a microwave roasting oven to be kept at the constant temperature of 1400 ℃ for 4 hours in the nitrogen atmosphere.
The carrier prepared above is put into the impregnation liquid, and the impregnation temperature is 80 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate and lanthanum nitrate, and the pH value is adjusted to 3 by nitric acid. Based on the weight of the catalyst, the iron content was 8%, the nickel content was 2%, and the lanthanum content was 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 6
Slowly dissolving starch, potassium hydroxide, ammonium polymethacrylate and TritonX100 in deionized water containing 2wt% of ethanol at 80 ℃ under stirring to obtain slurry A. Wherein, based on potassium hydroxide, the content of ammonium polymethacrylate is 2wt%, the content of TritonX100 is 0.5wt%, and the mass ratio of potassium hydroxide to starch is 3: 1.
Selecting flexible polyurethane foam with pore size of 100 ppi (pore per inch) and mutually communicated pores as a template, cutting into a certain shape, soaking in 20wt% NaOH solution for 10 hours, finally placing in deionized water for ultrasonic treatment for 5min, then washing with deionized water, and repeating for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying in a vacuum dryer at 60 ℃, taking out after 35min, repeating the process for 10 times, keeping the temperature at 500 ℃ for 8 hours in a nitrogen atmosphere, cooling, and washing with a 10wt% nitric acid solution at 25 ℃ until no activator ion is detected, thus obtaining the carbon template.
Dissolving sesbania powder and carboxymethyl cellulose in deionized water containing 0.1wt% of ethanol, adjusting the pH to 1 by using nitric acid, and slowly adding sodium silicate under stirring at 80 ℃ to slowly turn the solution into slurry to obtain slurry B. Wherein, the sesbania powder content is 5wt% and the carboxymethyl cellulose content is 4wt% based on the mass of the sodium silicate. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 80 ℃ in a vacuum dryer, taking out after 35min, and repeating the process for 10 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the microwave roasting furnace constant at 1600 ℃ for 24 hours in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The silicon carbide carrier is sent into a microwave roasting furnace, and the temperature is kept for 0.5 hour at 1300 ℃ in the mixed gas atmosphere of oxygen with the oxygen content of 5 percent and nitrogen. Cooling, adding into 2wt% NaOH solution, slowly heating to 60 deg.C, treating for 0.5 hr, cooling, placing into deionized water, ultrasonic treating for 5min, cleaning with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and roasting at 800 deg.C for 3 hr. Then the carrier is put into an impregnation liquid containing 1wt% of starch, is impregnated at 50 ℃, is dried at 120 ℃ after being impregnated, and is then sent into a microwave roasting oven to be kept at the constant temperature of 1400 ℃ for 0.5 hour in the nitrogen atmosphere.
The carrier prepared above was placed in an impregnation solution at an impregnation temperature of 60 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate and magnesium acetate, and the pH value is adjusted to 1 by hydrochloric acid. Based on the weight of the catalyst, the iron content was 5%, the nickel content was 1%, and the magnesium content was 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 7
Dextrin, phosphoric acid, polyethylene glycol (molecular weight is 400) and carboxymethyl cellulose are slowly dissolved in deionized water containing 20wt% of ethanol at 40 ℃ under stirring to obtain slurry A. Wherein, on the basis of phosphoric acid, the content of polyethylene glycol (molecular weight is 400) is 4wt%, the content of carboxymethyl cellulose is 6wt%, and the mass ratio of phosphoric acid to dextrin is 0.8: 1.
Selecting a soft polyurethane foam with a pore size of 150 ppi (pore per inch) and mutually communicated pores as a template, firstly cutting the foam into a certain shape, then soaking the foam in a 20wt% oxalic acid solution for 7 hours, finally placing the foam in deionized water for ultrasonic treatment for 5min, then washing the foam with the deionized water, and repeating the steps for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 120 ℃ in a vacuum dryer, taking out after 35min, repeating the process for 6 times, keeping the temperature at 800 ℃ for 3 hours in a nitrogen atmosphere, cooling, and washing with 15wt% of oxalic acid solution at 80 ℃ until no activator ions are detected, thus obtaining the carbon template.
Dissolving sesbania powder and hexamethylenetetramine in deionized water containing 80wt% of ethanol, adjusting the pH value to 7 by using oxalic acid, and slowly adding propyl orthosilicate under stirring at the temperature of 20 ℃ to slowly turn the solution into slurry to obtain slurry B. Wherein, the content of sesbania powder is 0.5wt% and the content of hexamethylenetetramine is 0.01wt% based on the mass of the propyl orthosilicate. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying at 120 ℃ in a vacuum drier, taking out after 35min, and repeating the process for 8 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the dried carrier constant at 1300 ℃ for 24 hours in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The silicon carbide carrier is sent into a microwave roasting furnace, and the temperature is kept for 6 hours at 1000 ℃ in the mixed gas atmosphere of oxygen with 60 percent of oxygen content and helium. Cooling, adding into 20wt% NaOH solution, slowly heating to 120 deg.C, treating for 0.5 hr, cooling, placing into deionized water, ultrasonic treating for 5min, cleaning with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and calcining at 800 deg.C for 3 hr. Then the carrier is put into an impregnation liquid containing 5wt% of glucose, impregnated at 90 ℃, dried at 120 ℃ after impregnation, and then sent into a microwave baking oven, and kept at the constant temperature of 1100 ℃ for 4 hours in a nitrogen atmosphere.
The carrier prepared above was put into the impregnation solution at an impregnation temperature of 50 ℃. The impregnation liquid contains ferrous acetate, nickel acetate, chromium nitrate and lanthanum nitrate, and the pH value is adjusted to 10 by phosphoric acid. Based on the weight of the catalyst, the iron content was 15%, the nickel content was 0.5%, the chromium content was 4.5%, and the lanthanum content was 0.1%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Example 8
Slowly dissolving water-soluble phenolic resin, potassium hydroxide, TritonX100 and carboxymethyl cellulose in deionized water containing 5wt% of ethanol at 60 ℃ under stirring to obtain slurry A. Wherein, on the basis of potassium hydroxide, the content of TritonX100 is 1wt%, the content of carboxymethyl cellulose is 9wt%, and the mass ratio of potassium hydroxide to water-soluble phenolic resin is 5: 1.
Selecting flexible polyurethane foam with pore size of 200ppi (pore per inch) and mutually communicated pores as a template, cutting into a certain shape, soaking in 1wt% nitric acid solution for 10 hours, finally placing in deionized water for ultrasonic treatment for 5min, then washing with deionized water, and repeating for 5 times. And (2) soaking the polyurethane foam into the slurry A, taking out, draining, drying at 140 ℃ in a vacuum dryer, taking out after 10min, repeating the process for 7 times, keeping the temperature of the mixture constant at 700 ℃ in a nitrogen atmosphere for 6 hours, cooling, and washing with deionized water at 50 ℃ until no activator ion is detected, thus obtaining the carbon template.
Dissolving microcrystalline cellulose and silica sol in deionized water containing 2wt% of ethanol, adjusting the pH to 10 by using ammonia water, and slowly adding tetraethoxysilane under the stirring at 120 ℃ to slowly turn the solution into slurry to obtain slurry B. Wherein, the content of microcrystalline cellulose is 0.5wt% and the content of silica sol is 5wt% based on the mass of the tetraethoxysilane. And (3) immersing the carbon template into the slurry B, taking out, blowing off redundant slurry among holes by using compressed air, drying in a vacuum dryer at 150 ℃, taking out after 5min, and repeating the process for 6 times.
And (3) conveying the dried carrier into a microwave roasting furnace, keeping the temperature of the microwave roasting furnace constant for 7 hours at 1600 ℃ in an argon atmosphere, soaking the carrier in 40wt% of hydrofluoric acid solution for 12 hours, placing the carrier in deionized water for ultrasonic treatment for 5min, then cleaning the carrier with the deionized water, and repeating the steps for 5 times. The silicon carbide carrier is sent into a microwave roasting furnace, and is kept at the constant temperature of 1200 ℃ for 8 hours in the atmosphere of the mixed gas of oxygen with the oxygen content of 80 percent and argon. Cooling, adding into 0.1wt% NaOH solution, slowly heating to 120 deg.C, treating for 5 hr, cooling, placing into deionized water, ultrasonic treating for 5min, cleaning with deionized water, repeating for 5 times, taking out, oven drying at 120 deg.C, and calcining at 800 deg.C for 3 hr. Then the carrier is put into an impregnation liquid containing 25wt% of glycerol, impregnated at 40 ℃, dried at 120 ℃ after impregnation, and then sent into a microwave roasting oven, and the temperature is kept constant at 1500 ℃ for 0.5 hour in a nitrogen atmosphere.
The carrier prepared above was placed in an impregnation solution at an impregnation temperature of 25 ℃. The impregnation liquid contains ferric nitrate, nickel nitrate, cerium nitrate and zirconyl nitrate, and the pH value is adjusted to 3 by oxalic acid. Based on the weight of the catalyst, the content of iron is 8%, the content of nickel is 1%, the content of cerium is 0.5%, and the content of zirconium is 0.5%. Drying the impregnated catalyst at 120 ℃, then sending the dried catalyst into a microwave roasting furnace, and keeping the temperature of the microwave roasting furnace at 800 ℃ for 3 hours in a nitrogen atmosphere.
Evaluation of catalyst Performance:
the pore structure properties of the supports prepared in examples 1 to 8 were measured using an ASAP 2460 type specific surface area and porosity analyzer, and the results are shown in Table 1:
TABLE 1 catalyst pore Structure Properties
Catalyst and process for producing the same
|
Specific surface area (m)2/g)
|
Pore volume (cm)3/g)
|
Example 1
|
225
|
0.66
|
Example 2
|
94
|
0.23
|
Example 3
|
236
|
0.63
|
Example 4
|
108
|
0.28
|
Example 5
|
217
|
0.61
|
Example 6
|
318
|
0.81
|
Example 7
|
203
|
0.53
|
Example 8
|
427
|
0.95 |
Toluene, phenol and naphthalene were used as tar model compounds, and simulated biomass gasification gas and steam were introduced, and the activity and life of the catalyst were evaluated using a fixed bed evaluation apparatus. Simulating biomass gasification gas flowThe amount is 500mL/min, and the proportion of each component is H 2 20%、CO 29.5%、CH4 10.2%、CO2 15%、N2 25.3%,H2The O flow is 0.15 mL/min, the tar model compound flow is 0.15 mL/min, wherein the ratio of toluene: phenol: the naphthalene molar ratio was 10:2: 0.5. And adding a certain amount of quartz sand to dilute the catalyst at the reaction temperature of 650-750 ℃ to about 5mL, adding the catalyst into a quartz tube reactor, raising the reaction temperature, introducing biomass gasification gas, water and tar model compounds to perform continuous experiments, and evaluating for 48 h. After the reaction tail gas is absorbed by a cold organic solvent, on-line continuous monitoring is carried out by using a Micro 490 type gas chromatography, the yield of the tar cracking gas is calculated according to the flow of each gas component before and after the reaction, and the tar cracking conversion rate is calculated by adopting GC-MS for off-line analysis after the reaction of the organic solvent. The evaluation results of the catalysts obtained in examples 1 to 8 are shown in Table 2.
In order to further examine the service life of the catalyst, the tar cracking conversion rate after 100 hours of operation was examined by using the catalyst obtained in example 5 as a sample, and after a 100-hour evaluation experiment, the tar cracking conversion rate of the catalyst obtained in example 5 was maintained at 98.7%.
TABLE 2 evaluation results of catalysts
Catalyst and process for preparing same
|
Average tar cracking conversion
|
Average tar cracking gas yield
|
Example 1
|
95.63
|
95.42
|
Example 2
|
94.16
|
94.03
|
Example 3
|
98.37
|
98.04
|
Example 4
|
98.14
|
97.93
|
Example 5
|
99.91
|
99.78
|
Example 6
|
99.84
|
99.67
|
Example 7
|
99.21
|
99.13
|
Example 8
|
99.47
|
99.23 |