A method for preparing a toluene waste gas catalytic cracking agent

Abstract

The invention discloses a method for preparing a catalytic cracking agent for toluene waste gas, comprising the following steps: (1) preparing phosphomolybdic divanadic acid; (2) preparing an ion catalyst solution and temporarily storing it in a nitrogen-protected container; (3) taking a methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin and adding them into a reactor, heating while stirring, stopping the reaction after keeping the temperature reaction for a period of time, and cooling to room temperature, taking the reaction solution and removing methanol by a rotary evaporator, and then extracting it by dichloromethane, and performing a desiccant after the extraction is completed to obtain a catalytic cracking agent. The advantage of the present invention is that by using lignin, phosphomolybdic divanadic acid and an ion catalyst to act synergistically, phosphomolybdic divanadic acid can effectively improve the catalytic cracking efficiency of lignin, and the ion catalyst can crack toluene waste gas into CO2, H2 and CH4 under high temperature roasting conditions, and can be subsequently recovered and collected, and the conversion rate is high, and the stability is also higher.

Description

Technical Field

[0001] The invention relates to the technical field of waste gas treatment, and in particular to a method for preparing a toluene waste gas catalytic cracking agent. Background Art

[0002] Toluene, as a representative of VOCs, mainly comes from industries such as building materials, steel smelting, kerosene refining, organic chemicals and furniture manufacturing. In particular, the steel smelting industry is the main source of air pollution. In the coking process, coal will be distilled under air-blocking conditions to generate a large amount of gas containing organic matter such as toluene, which is very harmful. Therefore, the study of efficient treatment technology for toluene pollutants has become a difficult problem that urgently needs to be broken through in today's society.

[0003] Traditional treatment technologies for toluene in industrial waste gas treatment mainly include adsorption, absorption, membrane separation, condensation, catalytic combustion, photocatalytic oxidation and biological methods, each of which has its own advantages and disadvantages. Common VOCs in industry are complex components. Some VOCs can be absorbed and removed by soluble in water, acid or alkali, such as amines, alcohols, carboxylic acids, etc., while VOCs containing benzene rings, such as toluene, are slightly soluble in water, acid or alkali, and have a stable chemical structure, making it difficult to purify them through a single technical equipment.

[0004] During the rapid development of my country, the increasingly serious environmental problems have attracted the attention of all sectors of society, giving rise to many technologies for the treatment of VOCs, such as activated carbon adsorption, plasma, ultraviolet light and other commonly used technologies. However, these purification technologies for VOCs have certain limitations, such as low adsorption capacity of activated carbon, easy adsorption saturation, short life, high regeneration cost, and eventually forming hazardous waste. If the equipment stops running, due to the loss of negative pressure, the adsorbed activated carbon will desorb and release VOCs; its operation is also affected by humidity, dust and temperature during operation. The higher the humidity, the more dust, and the worse the adsorption effect; the higher the temperature (the temperature in my country is long-term high in summer), the less conducive it is to adsorption. Low-temperature plasma technology will also reduce the treatment efficiency due to the influence of water vapor and dust in the exhaust gas. In addition, if low-energy plasma is used, the so-called plasma process now mostly adopts the principle of oil removal by range hoods, which is basically not suitable for the treatment of VOCs containing benzene rings. If high-power plasma technology is used, there are also disadvantages. The equipment is expensive. For example, if the plasma is excited to produce an arc, it will inevitably produce secondary pollutants such as ozone, nitrogen oxides and intermediate byproducts of partial degradation of organic waste gas. What's more serious is that since most of the organic waste gas is flammable and explosive compounds, the organic waste gas treatment project has a slight flaw in the design. The arc during plasma operation can easily cause an explosion accident. The explosion in Tianjin has informed everyone of its safety hazards. The time for this technology to be banned is running out. The application of ultraviolet photolysis technology will be affected by dust, which will continuously weaken the radiation energy, and the ultraviolet light with a wavelength of 185nm will produce a large amount of ozone, causing secondary pollution, and the current treatment method basically has no instantaneous reaction effect. As for the microbial method, it is also difficult to achieve instantaneous reaction to remove toluene in the high-concentration toluene waste gas in the convection state. As for the catalytic combustion method, it can purify some organic waste gas, but toluene is a non-flammable gas. If the combustion method is used, dioxin byproducts may be generated, causing secondary pollution. It can be seen that if each treatment equipment and its combination are used without quantitative analysis of the treatment and without researching targeted solutions, the waste gas from different emission sources will also be very different. A single technology for organic waste gas treatment has made it difficult for the emission of organic waste gas to meet the increasingly stringent environmental protection requirements. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a toluene waste gas catalytic cracking agent.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] A method for preparing a toluene waste gas catalytic cracking agent, characterized in that it comprises the following steps:

[0008] (1) Sodium metavanadate is dissolved in deionized water, and disodium hydrogen phosphate is added after the dissolution is completed. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added to dissolve. Concentrated sulfuric acid is added under strong stirring. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and the red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and water removal, crystals are obtained, which are phosphomolybdic divanadic acid.

[0009] (2) N-methylimidazole and 1-chlorobutane are added to an autoclave, heated and stirred under nitrogen protection to react, cooled to room temperature after the reaction is completed, and the mixture is passed through a rotary evaporator to remove the remaining unreacted substances, and the obtained product is dissolved in acetonitrile, and then the acetonitrile and water are removed through a vacuum drying oven. After drying, aluminum chloride is slowly added under nitrogen protection and stirred, and the obtained ion catalyst solution is temporarily stored in a nitrogen-protected container;

[0010] (3) A methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin are added to a reactor, and the temperature is raised while stirring. The temperature is maintained for a period of time, and then the reaction is stopped and cooled to room temperature. The reaction liquid is removed by a rotary evaporator to remove methanol, and then extracted with dichloromethane for at least four times. After the extraction is completed, a drying agent is used to obtain a catalytic cracking agent.

[0011] Preferably, the reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate in (1) is 1:(0.2-0.3):(2-3).

[0012] Preferably, the sodium metavanadate in (1) is dissolved in boiling deionized water, wherein the total amount of concentrated sulfuric acid used and the volume molar ratio of sodium metavanadate are (400-500 ml): 1 mol, and the ratio of the amount of concentrated sulfuric acid added in the two steps is 2:8.

[0013] Preferably, the middle liquid surface obtained after the extraction in (1) is purged in air to remove the ether.

[0014] Preferably, in (2), both N-methylimidazole and 1-n-chlorobutane are purified by distillation in advance, and the mass ratio of N-methylimidazole to 1-n-chlorobutane is 1:(6-8).

[0015] Preferably, the nitrogen pressure in (2) is 0.54-0.58 MPa, and the stirring temperature of the heating reaction is 80-85°C.

[0016] Preferably, the evaporation temperature of the rotary evaporator in (2) is 95°C, and the evaporation temperature of the rotary evaporator in (3) is 35-40°C.

[0017] Preferably, the mass volume ratio of lignin, phosphomolybdic divanadic acid and ionic catalyst solution in (3) is 1 g: (7-10 g): (4-11 ml).

[0018] Preferably, the reaction temperature of the methanol-water mixed solution, the ion catalyst solution and the lignin in the reaction vessel in (3) is 185-195° C., and the reaction time is 5-7 hours.

[0019] In summary, the present invention has the following beneficial effects: the present invention adopts lignin, phosphomolybdic divanadic acid and ionic catalyst for synergistic effect, phosphomolybdic divanadic acid can effectively improve the catalytic cracking efficiency of lignin, and the ionic catalyst can crack toluene waste gas into CO2, H2 and CH4 under high temperature roasting conditions, which can be recovered and collected later, with high conversion rate and higher stability. DETAILED DESCRIPTION

[0020] The specific implementation modes of the present invention are further described below, and these embodiments do not constitute a limitation of the present invention.

[0021] Example 1

[0022] A method for preparing a toluene waste gas catalytic cracking agent comprises the following steps:

[0023] (1) Sodium metavanadate is dissolved in boiling deionized water. After the dissolution is completed, disodium hydrogen phosphate is added. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added to dissolve. The reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate is 1:0.2:2. Concentrated sulfuric acid is added under strong stirring. The total amount of concentrated sulfuric acid and the volume molar ratio of sodium metavanadate are 400ml:1mol. The ratio of the amount of concentrated sulfuric acid added in the two steps is 2:8. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and purged in the air to remove the ether. The red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and dehydration, crystals are obtained, which are phosphomolybdic divanadic acid.

[0024] (2) N-methylimidazole and 1-chlorobutane which have been purified by distillation in advance are added to an autoclave in a mass ratio of 1:6. The mixture is heated to 80°C and stirred for reaction under the protection of 0.54 MPa nitrogen. After the reaction is completed, the mixture is cooled to room temperature. After cooling, the remaining unreacted substances are removed by a rotary evaporator at 95°C. The obtained product is dissolved in acetonitrile, and the acetonitrile and water are removed by a vacuum drying oven. After drying, aluminum chloride is slowly added under the protection of nitrogen and stirred. The obtained ion catalyst solution is temporarily stored in a nitrogen-protected container.

[0025] (3) A methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin are added into a reactor, wherein the mass volume ratio of lignin, phosphomolybdic divanadic acid and ion catalyst solution is 1 g:7 g:4 ml. The temperature is raised to 185°C while stirring, and the reaction is stopped after maintaining the temperature for 5 hours. The reaction is cooled to room temperature, and the reaction liquid is removed from the methanol by a rotary evaporator at 35°C, and then extracted with dichloromethane for at least four times. After the extraction is completed, a drying agent is used to obtain a catalytic cracking agent.

[0026] Example 2

[0027] A method for preparing a toluene waste gas catalytic cracking agent comprises the following steps:

[0028] (1) Sodium metavanadate is dissolved in boiling deionized water. After the dissolution is completed, disodium hydrogen phosphate is added. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added to dissolve. The reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate is 1:0.3:2. Concentrated sulfuric acid is added under strong stirring. The total amount of concentrated sulfuric acid and the volume molar ratio of sodium metavanadate are 450ml:1mol. The ratio of the amount of concentrated sulfuric acid added in the two steps is 2:8. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and purged in the air to remove the ether. The red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and dehydration, crystals are obtained, which are phosphomolybdic divanadic acid.

[0029] (2) N-methylimidazole and 1-chlorobutane which have been purified by distillation are added to an autoclave in a mass ratio of 1:7. The mixture is heated to 82°C and stirred for reaction under the protection of 0.55 MPa nitrogen. After the reaction is completed, the mixture is cooled to room temperature. After cooling, the remaining unreacted substances are removed by a rotary evaporator at 95°C. The obtained product is dissolved in acetonitrile, and the acetonitrile and water are removed by a vacuum drying oven. After drying, aluminum chloride is slowly added under the protection of nitrogen and stirred. The obtained ion catalyst solution is temporarily stored in a nitrogen-protected container.

[0030] (3) A methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin are added into a reactor, wherein the mass volume ratio of lignin, phosphomolybdic divanadic acid and ion catalyst solution is 1 g:8 g:7 ml. The temperature is raised to 190°C while stirring, and the temperature is maintained for 6 hours before the reaction is stopped and cooled to room temperature. The reaction liquid is removed from the methanol by a rotary evaporator at 37°C, and then extracted with dichloromethane for at least four times. After the extraction is completed, a drying agent is used to obtain a catalytic cracking agent.

[0031] Example 3

[0032] A method for preparing a toluene waste gas catalytic cracking agent comprises the following steps:

[0033] (1) Sodium metavanadate is dissolved in boiling deionized water. After the dissolution is completed, disodium hydrogen phosphate is added. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added to dissolve. The reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate is 1:0.3): 3. Concentrated sulfuric acid is added under strong stirring. The total amount of concentrated sulfuric acid and the volume molar ratio of sodium metavanadate are 480ml:1mol. The ratio of the amount of concentrated sulfuric acid added in the two steps is 2:8. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and purged in the air to remove the ether. The red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and dehydration, crystals are obtained, which are phosphomolybdic divanadic acid.

[0034] (2) N-methylimidazole and 1-chlorobutane which have been purified by distillation are added to an autoclave in a mass ratio of 1:8. The mixture is heated to 84°C and stirred for reaction under the protection of 0.58 MPa nitrogen. After the reaction is completed, the mixture is cooled to room temperature. After cooling, the remaining unreacted substances are removed by a rotary evaporator at 95°C. The obtained product is dissolved in acetonitrile, and the acetonitrile and water are removed by a vacuum drying oven. After drying, aluminum chloride is slowly added under the protection of nitrogen and stirred. The obtained ion catalyst solution is temporarily stored in a nitrogen-protected container.

[0035] (3) A methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin are added into a reactor, wherein the mass volume ratio of lignin, phosphomolybdic divanadic acid and ion catalyst solution is 1 g:9 g:10 ml. The temperature is raised to 193°C while stirring, and the reaction is stopped after maintaining the temperature for 6 hours. The reaction is cooled to room temperature, and the reaction solution is subjected to a rotary evaporator at 38°C to remove methanol, and then extracted with dichloromethane for at least four times. After the extraction is completed, a drying agent is used to obtain a catalytic cracking agent.

[0036] Example 4

[0037] A method for preparing a toluene waste gas catalytic cracking agent comprises the following steps:

[0038] (1) Sodium metavanadate is dissolved in boiling deionized water. After the dissolution is completed, disodium hydrogen phosphate is added. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added for dissolution. The reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate is 1:0.3:3. Concentrated sulfuric acid is added under strong stirring. The total amount of concentrated sulfuric acid and the volume molar ratio of sodium metavanadate are 500ml:1mol. The ratio of the amount of concentrated sulfuric acid added in the two steps is 2:8. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and purged in the air to remove the ether. The red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and dehydration, crystals are obtained, which are phosphomolybdic divanadic acid.

[0039] (2) N-methylimidazole and 1-chlorobutane which have been purified by distillation are added to an autoclave in a mass ratio of 1:8. The mixture is heated to 85°C and stirred for reaction under the protection of 0.58 MPa nitrogen. After the reaction is completed, the mixture is cooled to room temperature. After cooling, the remaining unreacted substances are removed by a rotary evaporator at 95°C. The obtained product is dissolved in acetonitrile, and the acetonitrile and water are removed by a vacuum drying oven. After drying, aluminum chloride is slowly added under the protection of nitrogen and stirred. The obtained ion catalyst solution is temporarily stored in a nitrogen-protected container.

[0040] (3) A methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin are added into a reactor, wherein the mass volume ratio of lignin, phosphomolybdic divanadic acid and ion catalyst solution is 1 g:10 g:11 ml. The temperature is raised to 195°C while stirring, and the reaction is stopped after maintaining the temperature for 7 hours. The reaction is cooled to room temperature, and the reaction liquid is removed from the methanol by a rotary evaporator at 40°C, and then extracted with dichloromethane for at least four times. After the extraction is completed, a drying agent is used to obtain a catalytic cracking agent.

[0041] The present invention adopts lignin, phosphomolybdic divanadic acid and ion catalyst for synergistic effect. Phosphomolybdic divanadic acid can effectively improve the catalytic cracking efficiency of lignin. At the same time, the ion catalyst can crack toluene waste gas into CO2, H2 and CH4 under high-temperature roasting conditions, which can be recovered and collected later. The conversion rate is high and the stability is also higher.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a toluene waste gas catalytic cracking agent, characterized in that: The steps include: (1) Sodium metavanadate is dissolved in deionized water, and disodium hydrogen phosphate is added after the dissolution is completed. After cooling, concentrated sulfuric acid is added. After the solution turns dark red, sodium molybdate is added to dissolve. Concentrated sulfuric acid is added under strong stirring. The solution is cooled to room temperature and extracted with ether. The middle liquid surface is taken and the red solid in the middle liquid surface is dissolved in deionized water. After vacuum drying and dehydration, crystals are obtained, which are phosphomolybdic divanadic acid. (2) N-methylimidazole and 1-chlorobutane are added to an autoclave, heated and stirred under nitrogen protection to react, cooled to room temperature after the reaction is completed, and the mixture is passed through a rotary evaporator to remove the remaining unreacted substances, and the obtained product is dissolved in acetonitrile, and then the acetonitrile and water are removed through a vacuum drying oven. After drying, aluminum chloride is slowly added under nitrogen protection and stirred, and the obtained ion catalyst solution is temporarily stored in a nitrogen-protected container; (3) adding a methanol-water mixed solution of phosphomolybdic divanadic acid, an ion catalyst solution and lignin into a reactor, heating the reactor while stirring, maintaining the temperature for a period of time, stopping the reaction, and cooling the reactor to room temperature. The reaction solution was removed by a rotary evaporator to remove methanol, and then extracted with dichloromethane for at least four times. After the extraction, the reaction solution was dried to obtain a catalytic cracking agent. The mass volume ratio of lignin, phosphomolybdic divanadic acid and ion catalyst solution is 1g: (7~10g): (4~11ml); The reaction temperature of the methanol-water mixed solution, the ion catalyst solution and the lignin in the reactor is 185-195° C., and the reaction time is 5-7 hours.

2. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: The reaction molar ratio of sodium metavanadate, disodium hydrogen phosphate and sodium molybdate in (1) is 1: (0.2-0.3): (2-3).

3. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: The sodium metavanadate in (1) is dissolved in boiling deionized water, wherein the total amount of concentrated sulfuric acid and the volume molar ratio of sodium metavanadate are (400-500 ml): 1 mol, and the ratio of the amount of concentrated sulfuric acid added in the two steps is 2:

8.

4. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: The middle liquid surface obtained after the extraction in (1) is purged in the air to remove the ether.

5. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: In the (2), both N-methylimidazole and 1-chlorobutane are purified by distillation in advance, and the mass ratio of N-methylimidazole to 1-chlorobutane is 1:(6-8).

6. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: The nitrogen pressure in (2) is 0.54-0.58 MPa, and the stirring temperature of the heating reaction is 80-85°C.

7. The method for preparing a toluene waste gas catalytic cracking agent according to claim 1, characterized in that: The evaporation temperature of the rotary evaporator in (2) is 95°C, and the evaporation temperature of the rotary evaporator in (3) is 35-40°C.