Method for co-producing carbon gas and synchronously preparing straw activated carbon and combustible gas and application

Abstract

The invention discloses a method for synchronously preparing straw activated carbon and combustible gas through carbon gas co-production and application, and relates to a method for preparing straw activated carbon and combustible gas and application. The invention aims to solve the problems of low straw high-end utilization level, high energy consumption, complex process, secondary pollution and poor environmental adaptability when the straws are converted into the clean synthesis gas in the prior art. According to the method, straw is taken as a raw material, and high-performance activated carbon and CH4 and H2 gas are synchronously prepared through efficient gasification, activation and multistage membrane separation and purification, so that straw agricultural and sideline products are comprehensively utilized; by means of the method, high-performance activated carbon can be scientifically, reasonably, greenly and efficiently prepared, CH4 and H2 with high purity are obtained, and combustion waste heat of CH4 and H2 can be used for heating; meanwhile, the prepared straw activated carbon has a high specific surface area and a rich pore structure, and can effectively adsorb heavy metal cadmium (Cd (II)). The method is simple in technological process and beneficial to industrial production.

Description

Technical Field

[0001] The invention relates to a method for preparing straw activated carbon and combustible gas and application thereof. Background Art

[0002] Due to massive carbon dioxide emissions, the global greenhouse effect is intensifying. In addition to industrial emission reduction measures, sequestering and storing atmospheric CO2 is equally important. Crops play an indispensable role in carbon sequestration, fixing atmospheric CO2 into their organic carbohydrates through photosynthesis. Corn straw, an agricultural byproduct, is the stem and leaf portion remaining after the corn crop matures and is a valuable renewable resource. my country boasts abundant straw resources, with an annual output of approximately 800 million tons. The three northeastern provinces are particularly rich in corn straw resources and have a high density. Statistics show that from 2011 to 2020, Heilongjiang Province produced an average of 31.4849 million tons of corn straw annually. However, due to inadequate comprehensive utilization planning, crude and extensive processing methods, and a low level of high-end utilization, a large amount of straw is still disposed of through open-air burning. This not only wastes resources but also seriously impacts air quality.

[0003] Straw is rich in cellulose, hemicellulose, and lignin. During gasification, it produces gases such as CO, CO2, H2, and CH4. Methane, hydrogen, and carbon monoxide can be separated and purified at multiple stages, serving as fuel gas or raw materials for the synthesis of new materials. Furthermore, it produces a solid product, biochar, which, through further activation, can be converted into high-value-added activated carbon. Due to its high specific surface area and porous structure, activated carbon exhibits superior adsorption capacity, high chemical stability, and strong charge storage capacity, making it suitable for applications in flue gas desulfurization, water purification, and supercapacitor electrode preparation.

[0004] Traditional biomass gasification can convert renewable resources into clean synthesis gas (H2, CO, CH4, etc.). However, the complex gas composition of the gasification products (such as tar, dust, acidic gas and multi-component mixed gas) seriously restricts its efficient utilization downstream. Although traditional separation technologies (such as pressure swing adsorption, cryogenic distillation, chemical absorption, etc.) can achieve partial purification, they generally have problems such as high energy consumption, complex processes, secondary pollution, and poor environmental adaptability. In recent years, inorganic membrane separation technology has shown unique advantages in the field of high-temperature gas separation due to its high thermal stability, chemical corrosion resistance and adjustable pore size / surface properties. In particular, the multi-stage inorganic membrane system can achieve cascade purification from crude fuel gas to high value-added products by connecting different selective membrane layers in series, and has both high efficiency and process integration potential. Therefore, the construction of a multi-stage inorganic membrane separation and purification technology system is not only a scientific need to break through the barriers to efficient utilization of biomass energy, but also a key direction to promote the upgrading of green chemical industry and clean energy industry. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems of low level of existing high-end utilization of straw, high energy consumption, complex process, secondary pollution and poor environmental adaptability in converting straw into clean synthesis gas, and to provide a method and application for the simultaneous preparation of straw activated carbon and combustible gas by carbon-gas co-production.

[0006] A method for simultaneously preparing straw activated carbon and combustible gas by carbon-gas cogeneration is completed by the following steps:

[0007] 1. Grinding the straw in a grinder, sieving, and drying to obtain pulverized straw;

[0008] 2. Place the crushed straw and corundum balls into a polytetrafluoroethylene ball mill, and then place the ball mill into a planetary ball mill for ball milling to obtain straw powder;

[0009] 3. Place the straw powder in a tubular furnace and calcine it in sections with controlled temperature to obtain solid reaction products and gaseous reaction products;

[0010] 4. Activating the solid reaction product with water vapor to obtain straw activated carbon;

[0011] 5. The gaseous reaction products are introduced into a multi-stage inorganic membrane gas separation and purification system, and are gradually processed through a ceramic multi-cyclone dust collector 1, a high-pressure electrostatic washing tower 2, a NaOH packing tower 3, a security filter 4, a functional ceramic membrane 5, a CORMs functional membrane 6, a metal organic framework functional membrane 7 and an MDEA spray tower multi-stage separation device 8 in the multi-stage inorganic membrane gas separation and purification system to remove tar, dust, acidic gas and CO, and collect and purify H2 and CH4 gas products step by step to obtain combustible gas.

[0012] Principle of the present invention:

[0013] The present invention uses straw as raw material and simultaneously prepares high-performance activated carbon and CH4 and H2 gases through high-efficiency gasification-activation-multi-stage membrane separation and purification, so that straw agricultural and sideline products can be comprehensively utilized. The method of the present invention can be used to scientifically, rationally, greenly and efficiently prepare high-performance activated carbon, and obtain CH4 and H2 with high purity, and the waste heat of combustion can be used for heating. At the same time, the prepared straw activated carbon has a high specific surface area and a rich pore structure, and can effectively adsorb heavy metals such as cadmium Cd(II). CH4 and H2 can be used as combustible gas and also as raw materials for preparing new materials. The present invention can effectively realize waste resource utilization, energy conservation and emission reduction, and water pollution treatment. At the same time, no external chemical agents are required in the whole process, the process flow is simple, and it is conducive to industrial production.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention uses straw as raw material, and all raw materials come only from the corn straw processing industry chain;

[0016] Second, the method of the present invention adopts gasification-physical activation combined with staged temperature control. The use of steam activation is easy to realize integrated combination with biomass gasification, which is conducive to shortening the process flow, saving costs, and not causing secondary pollution.

[0017] 3. The present invention has developed a unique multi-stage inorganic membrane gas separation and purification system. The combustible components in the straw undergo drying, pyrolysis, oxidation and reduction at high temperature to produce gases such as CO, H2, CH4, and CO2. These gases are then passed through a multi-stage separation device including a ceramic multi-cyclone dust collector, a high-pressure electrostatic scrubber, a NaOH packing tower, a security filter, a functional ceramic membrane, a CORMs functional membrane, a metal-organic framework functional membrane, and an MDEA (methyldiethanolamine) solution spray tower. This system can gradually remove wastes such as tar, dust, acidic gases, CO, and CO2, while collecting and purifying high-value-added gas products such as H2 and CH4 step by step.

[0018] Fourth, the large amount of heat released in the oxidation stage of the present invention can be used in the drying, pyrolysis and reduction stages through heat conduction, thereby realizing the comprehensive utilization of gas, solid and heat in gasification preparation; at the same time, the whole process does not require the addition of external chemical agents, the process flow is simple, and it is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the SEM image of the straw activated carbon prepared in Example 1;

[0020] Figure 2 This is the N2 adsorption and desorption curve of the straw activated carbon prepared in Example 1;

[0021] Figure 3 This is an infrared spectrum scan of the straw activated carbon prepared in Example 1;

[0022] Figure 4 This is a schematic structural diagram of the multi-stage inorganic membrane gas separation and purification system described in Example 1. In the figure, 1 is a ceramic multi-cyclone dust collector, 2 is a high-pressure electrostatic washing tower, 3 is a NaOH packing tower, 4 is a security filter, 5 is a functional ceramic membrane, 6 is a CORMs functional membrane, 7 is a metal-organic framework functional membrane, and 8 is an MDEA spray tower multi-stage separation device. DETAILED DESCRIPTION

[0023] Specific embodiment 1: This embodiment provides a method for simultaneously preparing straw activated carbon and combustible gas by carbon-gas cogeneration, which is specifically completed by the following steps:

[0024] 1. Grinding the straw in a grinder, sieving, and drying to obtain pulverized straw;

[0025] 2. Place the crushed straw and corundum balls into a polytetrafluoroethylene ball mill, and then place the ball mill into a planetary ball mill for ball milling to obtain straw powder;

[0026] 3. Place the straw powder in a tubular furnace and calcine it in sections with controlled temperature to obtain solid reaction products and gaseous reaction products;

[0027] 4. Activating the solid reaction product with water vapor to obtain straw activated carbon;

[0028] 5. The gaseous reaction products are introduced into a multi-stage inorganic membrane gas separation and purification system, and are gradually processed through a ceramic multi-cyclone dust collector 1, a high-pressure electrostatic washing tower 2, a NaOH packing tower 3, a security filter 4, a functional ceramic membrane 5, a CORMs functional membrane 6, a metal organic framework functional membrane 7 and an MDEA spray tower multi-stage separation device 8 in the multi-stage inorganic membrane gas separation and purification system to remove tar, dust, acidic gas and CO, and collect and purify H2 and CH4 gas products step by step to obtain combustible gas.

[0029] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that: the straw described in step 1 is corn straw; the drying temperature in step 1 is 150°C to 180°C, and the drying time is 1.5 hours to 2 hours; in step 1, the straw is crushed in a grinder and then passed through a 200-300 mesh sieve; the mass ratio of the crushed straw to corundum balls in step 2 is (5-7):90; the ball milling time in step 2 is 2 hours to 2.5 hours, and the ball milling speed is 600 rpm to 700 rpm. The other steps are the same as specific embodiment 1.

[0030] Specific embodiment three: This embodiment differs from specific embodiments one or two in that the specific process of the staged temperature-controlled calcination described in step three is as follows: under nitrogen atmosphere protection, heating to 400°C to 600°C at a heating rate of 5°C / min for 2 to 2.5 hours, then heating to 700°C to 800°C at a heating rate of 5°C / min for 1.5 to 2.5 hours, and finally cooling to 550°C to 600°C at a cooling rate of 5°C / min, and maintaining the temperature at 550°C to 600°C for 1 to 2 hours. The other steps are the same as those in specific embodiments one or two.

[0031] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the specific process for steam activation of the solid reaction product in step 4 is as follows: heating the tubular furnace to 800°C to 900°C, introducing steam into the tubular furnace, and performing steam activation for 1.5 to 2.5 hours at a steam flow rate of 2.5 to 3.5 kg / h. The mass ratio of steam to solid reaction product is 1:(1 to 2), thereby obtaining straw activated carbon. The other steps are the same as those of specific embodiments 1 to 3.

[0032] Specific Embodiment 5: This embodiment differs from Specific Embodiments 1 to 4 in that the multi-stage inorganic membrane gas separation and purification system described in Step 5 comprises a ceramic multi-cyclone dust collector 1, a high-pressure electrostatic scrubber 2, a NaOH packed tower 3, a safety filter 4, a functional ceramic membrane 5, a CORMs functional membrane 6, a metal-organic framework functional membrane 7, and an MDEA spray tower multi-stage separation device 8 connected in series. The ceramic multi-cyclone dust collector 1, high-pressure electrostatic scrubber 2, and NaOH packed tower 3 constitute the pretreatment system, while the safety filter 4, functional ceramic membrane 5, CORMs functional membrane 6, and metal-organic framework functional membrane 7 constitute the purification and separation system. The remaining steps are the same as in Specific Embodiments 1 to 4.

[0033] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the functional ceramic film 5 in step 5 is made of Fe-MnOx material, and the molar ratio of Fe:Mn in the Fe-MnOx material is (1-3):(1-3); the preparation method of the Fe-MnOx material is as follows:

[0034] ①. Mix 1g / L to 3g / L of ferrous sulfate solution and 1g / L to 3g / L of manganese sulfate solution in a certain volume ratio, and then oxidize with an oxidizing solution for 3 to 5 hours to form an iron-manganese mixed oxide particle suspension;

[0035] The molar ratio of Fe:Mn in the iron-manganese mixed oxide particle suspension described in step ① is (1-3):(1-3);

[0036] The volume ratio of the ferrous sulfate solution to the oxidizing solution in step ① is (2-6):1;

[0037] The oxidizing solution described in step ① is a sodium hypochlorite solution with a concentration of 0.5 mg / L to 2 mg / L, a potassium permanganate solution with a concentration of 0.5 mg / L to 2 mg / L, or a hydrogen peroxide solution with a concentration of 0.5 mg / L to 2 mg / L;

[0038] ②. Filter the iron-manganese mixed oxide particle suspension onto a commercial ultrafiltration ceramic membrane at a filtration rate of 1 mL / min to 20 mL / min. After every 30 to 120 minutes of filtration, backwash with pure water at a rate of 50 mL / min to 100 mL / min for 30 to 120 minutes.

[0039] ③. Repeat step ② 3 to 10 times, and then dry to obtain Fe-MnOx material. The other steps are the same as those in specific embodiments 1 to 5.

[0040] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the coordination center of the CORMs functional film 6 in step 5 is metal ruthenium, and the preparation method is as follows:

[0041] ① Under a nitrogen atmosphere, ruthenium trichloride and iron pentacarbonyl were dissolved in tetrahydrofuran at 45°C to 60°C, stirred and reacted for 6 hours, and then the reaction product was washed three times with deionized water and anhydrous ethanol respectively, and finally vacuum dried to obtain Ru-CORMs; the Ru-CORMs were dispersed in anhydrous ethanol to obtain a 0.5 mg / mL Ru-CORMs ethanol solution;

[0042] The molar ratio of ruthenium trichloride to iron pentacarbonyl described in step ① is 1:(2-4);

[0043] The volume ratio of the amount of ruthenium trichloride described in step ① to tetrahydrofuran is 1 mol:1 L;

[0044] ②, polystyrene microspheres with a particle size of 1 μm were added dropwise to a 0.5 mg / mL Ru-CORMs ethanol solution, ultrasonically mixed for 30 min to 60 min, and then centrifuged at a centrifugal speed of 8000 rpm to 10000 rpm for 10 min to 15 min. The microspheres were collected and dried at 60°C for a period of time to obtain Ru-CORMs-coated micro-nanomotors;

[0045] The mass ratio of the polystyrene microspheres to the Ru-CORMs in step ② is (10-15):1;

[0046] ③ Disperse the Ru-CORMs-coated micro-nanomotor in a 0.1 mol / L citrate buffer solution with a pH of 5, then add PEG-2000 polyethylene glycol and stir for 2 to 3 hours to obtain the modified micro-nanomotor.

[0047] The mass fraction of the Ru-CORMs-coated micro-nanomotor in the modified micro-nanomotor described in step ③ is 1% to 3%, and the mass fraction of PEG-2000 polyethylene glycol is 1% to 2%;

[0048] ④. Evenly mix the modified micro-nanomotors obtained in step ③ with polysulfone particles, dissolve them in N,N-dimethylformamide, and ultrasonically disperse them for 1 to 2 hours to obtain a modified solution;

[0049] The mass fraction of the modified micro-nanomotors in the modification solution in step ④ is 5%, and the mass fraction of the polysulfone particles is 15%;

[0050] ⑤. The modified liquid was scraped onto a glass plate to a thickness of 150 μm. The plate was then immersed in a water coagulation bath for 10 seconds to form a porous membrane. The membrane was then removed, and the residual solvent was replaced with anhydrous ethanol. The membrane was then attached to the surface of a commercial ultrafiltration ceramic membrane and dried at room temperature for 20 to 24 hours to obtain a CORMs functional membrane 6. The remaining steps were the same as those in Specific Embodiments 1 to 6.

[0051] Specific embodiment eight: This embodiment differs from specific embodiments one to seven in that the metal organic framework functional membrane 7 described in step five is copper-based or zinc-based, and the preparation method is as follows:

[0052] ①. Ultrasonic cleaning of the commercial ultrafiltration ceramic membrane with hydrochloric acid, anhydrous ethanol and ultrapure water for 30 minutes respectively. Then, the cleaned commercial ultrafiltration ceramic membrane is immersed in an acidic solution or an alkaline solution for a period of time, and then taken out to obtain a pretreated ultrafiltration ceramic membrane;

[0053] The preparation fraction of hydrochloric acid described in step ① is 3% to 5%;

[0054] The acidic solution described in step ① is a mixture of H2SO4 and H2O2, wherein the volume ratio of H2SO4 to H2O2 is 3:1, the mass fraction of H2SO4 is 5%, and the mass fraction of H2O2 is 10%;

[0055] The alkaline solution described in step ① is a mixed solution of ammonium persulfate and sodium hydroxide, wherein the mass fraction of ammonium persulfate is 2% and the mass fraction of sodium hydroxide is 5%;

[0056] ② Dissolve the metal salt and organic ligand in water or anhydrous ethanol to obtain a metal salt-organic ligand solution;

[0057] The metal salt described in step ② is zinc sulfate or copper sulfate;

[0058] The organic ligand in step ② is trimesic acid, tetracarboxyphenylporphyrin or 2,3,6,7,10,11-hexahydroxytriphenyl;

[0059] The concentration of the organic ligand in the metal salt-organic ligand solution in step ② is 5 mg / L, and the concentration of the metal salt is 2 mg / L;

[0060] ③. Immerse the pretreated ultrafiltration ceramic membrane in a metal salt-organic ligand solution for 1 hour to 2 hours, then take it out and immerse it in a hypochlorous acid solution or hydrogen peroxide solution at a temperature of 60℃ to 80℃ for oxidation for 1 hour;

[0061] The concentration of the hypochlorous acid solution in step ③ is 5%, and the concentration of the hydrogen peroxide solution is 10%;

[0062] ④. Repeat step ③ 5 to 10 times, dry, and obtain the metal organic framework functional membrane 7. The other steps are the same as those in the first to seventh embodiments.

[0063] Specific embodiment nine: This embodiment is that the straw activated carbon is used to adsorb heavy metal ions in sewage.

[0064] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the heavy metal ion in the sewage is Cd(II). The other steps are the same as those of specific embodiments 1 to 9.

[0065] The following examples are used to verify the beneficial effects of the present invention:

[0066] Example 1: A method for simultaneously preparing straw activated carbon and combustible gas by carbon-gas cogeneration, which is specifically completed by the following steps:

[0067] 1. Grind the straw in a grinder, pass it through a 300-mesh sieve, and then dry it at 180°C for 1.5 hours to obtain the pulverized straw;

[0068] The straw described in step 1 is corn straw;

[0069] 2. Place the crushed straw and corundum balls into a polytetrafluoroethylene ball mill, and then place the ball mill into a planetary ball mill for ball milling to obtain straw powder;

[0070] The mass ratio of the crushed straw to the corundum balls in step 2 is 6:90;

[0071] The ball milling time in step 2 is 2 h, and the ball milling speed is 600 r / min;

[0072] 3. Place the straw powder in a tubular furnace and calcine it in sections with controlled temperature to obtain solid reaction products and gaseous reaction products;

[0073] The specific process of the staged temperature-controlled calcination described in step 3 is as follows: under nitrogen atmosphere protection (flow rate of 0.5 L / min), heating to 600 ° C at a heating rate of 5 ° C / min, heating for 2 h, then heating to 800 ° C at a heating rate of 5 ° C / min, heating for 1.5 h, and finally cooling to 600 ° C at a cooling rate of 5 ° C / min, and keeping at 600 ° C for 1.5 h;

[0074] 4. Activating the solid reaction product with water vapor to obtain straw activated carbon;

[0075] The specific process of steam activation of the solid reaction product in step 4 is as follows: nitrogen is introduced into the tubular furnace to remove impurity gases in the tubular furnace, the tubular furnace is heated to 900° C., and steam is introduced into the tubular furnace. The steam activation time is 2 h, the steam flow rate is 3 kg / h, and the mass ratio of steam to solid reaction product is 1:1, thereby obtaining straw activated carbon;

[0076] 5. The gaseous reaction products are introduced into a multi-stage inorganic membrane gas separation and purification system, and are gradually processed through a ceramic multi-cyclone dust collector 1, a high-pressure electrostatic scrubber 2, a NaOH packing tower 3, a security filter 4, a functional ceramic membrane 5, a CORMs functional membrane 6, a metal organic framework functional membrane 7, and an MDEA spray tower multi-stage separation device 8 in the multi-stage inorganic membrane gas separation and purification system to remove tar, dust, acidic gas, and CO, and the H2 and CH4 gas products are collected and purified step by step to obtain combustible gas;

[0077] The multi-stage inorganic membrane gas separation and purification system described in step 5 is composed of a ceramic multi-cyclone dust collector 1, a high-pressure electrostatic scrubber 2, a NaOH packed tower 3, a security filter 4, a functional ceramic membrane 5, a CORMs functional membrane 6, a metal organic framework functional membrane 7, and an MDEA spray tower multi-stage separation device 8 connected in series; wherein the ceramic multi-cyclone dust collector 1, the high-pressure electrostatic scrubber 2, and the NaOH packed tower 3 constitute a pretreatment system, and the security filter 4, the functional ceramic membrane 5, the CORMs functional membrane 6, and the metal organic framework functional membrane 7 constitute a purification and separation system;

[0078] The functional ceramic membrane 5 described in step 5 is a Fe-MnOx material, and the molar ratio of Fe:Mn in the Fe-MnOx material is (1-3):(1-3); the preparation method of the Fe-MnOx material is as follows:

[0079] ① Mix 2g / L of ferrous sulfate solution and 2g / L of manganese sulfate solution in a certain volume ratio, and oxidize them with an oxidizing solution for 3 hours to form a suspension of iron-manganese mixed oxide particles;

[0080] The molar ratio of Fe:Mn in the iron-manganese mixed oxide particle suspension described in step ① is 1:1;

[0081] The volume ratio of the ferrous sulfate solution to the oxidizing solution in step ① is 4:1;

[0082] The oxidizing solution described in step ① is a sodium hypochlorite solution with a concentration of 1 mg / L;

[0083] ② Filter the iron-manganese mixed oxide particle suspension onto a commercial ultrafiltration ceramic membrane at a filtration rate of 10 mL / min. After every 60 minutes of filtration, backwash with pure water at a rate of 50 mL / min for 30 minutes.

[0084] ③, repeat step ② 3 to 10 times, and then dry to obtain Fe-MnOx material;

[0085] The coordination center of the CORMs functional film 6 described in step 5 is metallic ruthenium, and the preparation method is as follows:

[0086] ① Under a nitrogen atmosphere, ruthenium trichloride and iron pentacarbonyl were dissolved in tetrahydrofuran at 60°C and stirred for 6 hours. The reaction product was then washed three times with deionized water and anhydrous ethanol, respectively, and finally dried under vacuum to obtain Ru-CORMs. The Ru-CORMs were dispersed in anhydrous ethanol to obtain a 0.5 mg / mL Ru-CORMs ethanol solution.

[0087] The molar ratio of ruthenium trichloride to iron pentacarbonyl described in step ① is 1:3;

[0088] The volume ratio of the amount of ruthenium trichloride described in step ① to tetrahydrofuran is 1 mol:1 L;

[0089] ②, polystyrene microspheres with a particle size of 1 μm were added dropwise to a 0.5 mg / mL Ru-CORMs ethanol solution, ultrasonically mixed for 30 min to 60 min, and then centrifuged at a centrifugal speed of 8000 rpm for 10 min. The microspheres were collected and dried at 60°C for a period of time to obtain Ru-CORMs-coated micro-nanomotors;

[0090] The mass ratio of the polystyrene microspheres to the Ru-CORMs in step ② is (10-15):1;

[0091] ③ The Ru-CORMs-coated micro-nanomotors were dispersed in a citrate buffer solution with a concentration of 0.1 mol / L and a pH of 5, and PEG-2000 polyethylene glycol was added and stirred for 2 h to obtain the modified micro-nanomotors.

[0092] The mass fraction of the Ru-CORMs-coated micro-nanomotor in the modified micro-nanomotor described in step ③ is 1% to 3%, and the mass fraction of PEG-2000 polyethylene glycol is 2%;

[0093] ④. The modified micro-nanomotors obtained in step ③ were mixed evenly with polysulfone particles, dissolved in N,N-dimethylformamide, and ultrasonically dispersed for 2 h to obtain a modified solution;

[0094] The mass fraction of the modified micro-nanomotors in the modification solution in step ④ is 5%, and the mass fraction of the polysulfone particles is 15%;

[0095] ⑤. Scrape the modified liquid onto a glass plate with a thickness of 150 μm, then immerse it in a water coagulation bath for 10 seconds to form a porous membrane. After taking out the membrane, use anhydrous ethanol to replace the residual solvent, attach it to the surface of a commercial ultrafiltration ceramic membrane, and dry it at room temperature for 24 hours to obtain a CORMs functional membrane 6.

[0096] The metal organic framework functional membrane 7 described in step 5 is zinc-based and is prepared as follows:

[0097] ①. Ultrasonic cleaning of the commercial ultrafiltration ceramic membrane was performed using hydrochloric acid, anhydrous ethanol, and ultrapure water for 30 minutes respectively. The cleaned commercial ultrafiltration ceramic membrane was then immersed in an acidic solution for a period of time and then removed to obtain a pretreated ultrafiltration ceramic membrane.

[0098] The preparation fraction of hydrochloric acid described in step ① is 4%;

[0099] The acidic solution described in step ① is a mixture of H2SO4 and H2O2, wherein the volume ratio of H2SO4 to H2O2 is 3:1, the mass fraction of H2SO4 is 5%, and the mass fraction of H2O2 is 10%;

[0100] ② Dissolve the organic ligand and zinc sulfate in water or anhydrous ethanol to obtain a zinc sulfate-organic ligand solution;

[0101] The organic ligand in step ② is trimesic acid, tetracarboxyphenylporphyrin or 2,3,6,7,10,11-hexahydroxytriphenyl;

[0102] The concentration of the organic ligand in the zinc sulfate-organic ligand solution in step ② is 5 mg / L, and the concentration of zinc sulfate is 2 mg / L;

[0103] ③ Immerse the pretreated ultrafiltration ceramic membrane in a zinc sulfate-organic ligand solution for 2 hours, then immerse it in a hypochlorous acid solution at a temperature of 60°C to 80°C for oxidation for 1 hour;

[0104] The concentration of the hypochlorous acid solution described in step ③ is 5%;

[0105] ④. Repeat step ③ 5 to 10 times, dry, and obtain the metal organic framework functional membrane 7.

[0106] The gaseous reaction product obtained in step 3 of Example 1 is composed of H2 35%, CH4 15%, CO 20%, CO2 25%, and contains tar 5g / m 3 、Dust 10g / m 3, H2S 800ppm, after being treated by the multi-stage inorganic membrane gas separation and purification system in step five, the pollutant removal rates of tar>99.9%, dust>99.9%, H2S>99.5%, and CO>99% are achieved, and the product separation purity of H2≥99.97% and CH4≥95% is obtained.

[0107] Example 2: This example differs from Example 1 in that the specific process for steam activation of the solid reaction product in step 4 is as follows: the tubular furnace is heated to 900°C, steam is introduced into the tubular furnace, the steam activation time is 1 hour, the steam flow rate is 2.5 kg / h, and the mass ratio of steam to solid reaction product is 1:1, thereby obtaining straw activated carbon. Other steps and parameters are the same as in Example 1.

[0108] Figure 1 This is the SEM image of the straw activated carbon prepared in Example 1;

[0109] from Figure 1 It can be seen that after activation, the carbon forms a structure of stacked small sheets with good microporous structure and good physical adsorption performance.

[0110] Figure 2 This is the N2 adsorption and desorption curve of the straw activated carbon prepared in Example 1;

[0111] from Figure 2 It can be seen that the straw activated carbon prepared in Example 1 has sufficient pores and good adsorption performance.

[0112] Figure 3 This is an infrared spectrum scan of the straw activated carbon prepared in Example 1;

[0113] from Figure 3 It can be seen that the straw activated carbon prepared in Example 1 has rich surface functional groups and can exert more chemical adsorption effects in applications.

[0114] Application Example 1: The straw activated carbon prepared in Example 1 is used to adsorb heavy metal ions in sewage, which is accomplished by the following steps:

[0115] 20 mg of straw activated carbon prepared in Example 1 was added to 100 mL of 4 mg / L divalent cadmium Cd(II) solution, and then stirred at 150 r·min. -1 The mixture was stirred at a frequency of 10 minutes at 25°C, and then allowed to stand for adsorption for 12 hours. Finally, the solution after standing was filtered, and the filtrate was retained. The absorbance of the filtrate was measured, and the adsorption efficiency of Cd(II) was calculated. The results showed that the adsorption efficiency of Cd(II) was 47.25%.

[0116] Application Example 2: The straw activated carbon prepared in Example 2 is used to adsorb heavy metal ions in sewage, which is accomplished by the following steps:

[0117] 1 mg of straw activated carbon prepared in Example 2 was added to 100 mL of 0.1 mg / L divalent cadmium Cd(II) solution, and then stirred at 150 r·min. -1 The mixture was stirred at a frequency of 10 minutes at 25°C, then allowed to stand for adsorption for 1 hour. Finally, the solution after standing was filtered and the filtrate was retained. The absorbance of the filtrate was measured and the adsorption efficiency of Cd(II) was calculated. The results showed that the removal rate of Cd(II) was 99% and the residual concentration was <0.001 mg / L, which met the national standard limit requirements.

Claims

1. A method for simultaneously preparing straw activated carbon and combustible gas by carbon-gas cogeneration, characterized in that The method is specifically completed according to the following steps:

1. Grinding the straw in a grinder, sieving, and drying to obtain pulverized straw; 2. Place the crushed straw and corundum balls into a polytetrafluoroethylene ball mill, and then place the ball mill into a planetary ball mill for ball milling to obtain straw powder; 3. Place the straw powder in a tubular furnace and calcine it in sections with controlled temperature to obtain solid reaction products and gaseous reaction products; 4. Activating the solid reaction product with water vapor to obtain straw activated carbon; 5. The gaseous reaction products are introduced into a multi-stage inorganic membrane gas separation and purification system, and are gradually processed through a ceramic multi-cyclone dust collector (1), a high-pressure electrostatic washing tower (2), a NaOH packing tower (3), a security filter (4), a functional ceramic membrane (5), a CORMs functional membrane (6), a metal organic framework functional membrane (7) and an MDEA spray tower multi-stage separation device (8) in the multi-stage inorganic membrane gas separation and purification system to remove tar, dust, acidic gas and CO, and the H2 and CH4 gas products are collected and purified step by step to obtain combustible gas.

2. The method for synchronously preparing straw activated carbon and combustible gas by carbon cogeneration according to claim 1, characterized in that The straw described in step one is corn straw; the drying temperature described in step one is 150° C. to 180° C., and the drying time is 1.5 h to 2 h; in step one, the straw is crushed in a grinder and then passed through a 200-mesh to 300-mesh sieve; the mass ratio of the crushed straw to the corundum ball described in step two is (5-7):90; the ball milling time described in step two is 2 h to 2.5 h, and the ball milling speed is 600 r / min to 700 r / min.

3. The method for synchronously preparing straw activated carbon and combustible gas by carbon-gas cogeneration according to claim 1, characterized in that The specific process of the staged temperature-controlled calcination described in step three is as follows: under nitrogen atmosphere protection, heating to 400°C~600°C at a heating rate of 5°C / min, heating for 2h~2.5h, then heating to 700°C~800°C at a heating rate of 5°C / min, heating for 1.5h~2.5h, and finally cooling to 550°C~600°C at a cooling rate of 5°C / min, and keeping at 550°C~600°C for 1h~2h.

4. The method for synchronously preparing straw activated carbon and combustible gas by carbon cogeneration according to claim 1, characterized in that The specific process of steam activation of the solid reaction product in step 4 is: heating the tubular furnace to 800°C to 900°C, introducing water vapor into the tubular furnace, the water vapor activation time is 1.5h to 2.5h, the water vapor flow rate is 2.5kg / h to 3.5kg / h, the mass ratio of water vapor to solid reaction product is 1:(1~2), and straw activated carbon is obtained.

5. The method for synchronously preparing straw activated carbon and combustible gas by carbon-gas cogeneration according to claim 1, characterized in that The multi-stage inorganic membrane gas separation and purification system described in step five is composed of a ceramic multi-tube cyclone dust collector (1), a high-pressure electrostatic washing tower (2), a NaOH packed tower (3), a security filter (4), a functional ceramic membrane (5), a CORMs functional membrane (6), a metal organic framework functional membrane (7) and an MDEA spray tower multi-stage separation device (8) connected in series; wherein the ceramic multi-tube cyclone dust collector (1), the high-pressure electrostatic washing tower (2) and the NaOH packed tower (3) constitute a pretreatment system, and the security filter (4), the functional ceramic membrane (5), the CORMs functional membrane (6) and the metal organic framework functional membrane (7) constitute a purification and separation system.

6. The method for synchronously preparing straw activated carbon and combustible gas by carbon-gas cogeneration according to claim 1, characterized in that The functional ceramic membrane (5) described in step 5 is a Fe-MnOx material, and the molar ratio of Fe:Mn in the Fe-MnOx material is (1-3):(1-3); the preparation method of the Fe-MnOx material is as follows: ①. Mix 1g / L to 3g / L of ferrous sulfate solution and 1g / L to 3g / L of manganese sulfate solution in a certain volume ratio, and then oxidize with an oxidizing solution for 3h to 5h to form an iron-manganese mixed oxide particle suspension; The molar ratio of Fe:Mn in the iron-manganese mixed oxide particle suspension described in step ① is (1-3):(1-3); The volume ratio of the ferrous sulfate solution to the oxidizing solution in step ① is (2-6):1; The oxidizing solution described in step ① is a sodium hypochlorite solution with a concentration of 0.5 mg / L to 2 mg / L, a potassium permanganate solution with a concentration of 0.5 mg / L to 2 mg / L, or a hydrogen peroxide solution with a concentration of 0.5 mg / L to 2 mg / L; ②. Filter the iron-manganese mixed oxide particle suspension onto a commercial ultrafiltration ceramic membrane at a filtration rate of 1 mL / min to 20 mL / min. After every 30 to 120 minutes of filtration, backwash with pure water at a rate of 50 mL / min to 100 mL / min for 30 to 120 minutes. ③. Repeat step ② 3 to 10 times, and then dry to obtain Fe-MnOx material.

7. The method for synchronously preparing straw activated carbon and combustible gas by carbon-gas cogeneration according to claim 1, characterized in that The coordination center of the CORMs functional film (6) described in step 5 is metallic ruthenium, and the preparation method is as follows: ① Under a nitrogen atmosphere, ruthenium trichloride and iron pentacarbonyl were dissolved in tetrahydrofuran at 45°C to 60°C, stirred and reacted for 6 hours, and then the reaction product was washed three times with deionized water and anhydrous ethanol respectively, and finally vacuum dried to obtain Ru-CORMs; the Ru-CORMs were dispersed in anhydrous ethanol to obtain a 0.5 mg / mL Ru-CORMs ethanol solution; The molar ratio of ruthenium trichloride to iron pentacarbonyl described in step ① is 1:(2-4); The volume ratio of the amount of ruthenium trichloride described in step ① to tetrahydrofuran is 1 mol:1 L; ②, polystyrene microspheres with a particle size of 1 μm were added dropwise to a 0.5 mg / mL Ru-CORMs ethanol solution, ultrasonically mixed for 30 min to 60 min, and then centrifuged at a centrifugal speed of 8000 rpm to 10000 rpm for 10 min to 15 min. The microspheres were collected and dried at 60°C for a period of time to obtain Ru-CORMs-coated micro-nanomotors; The mass ratio of the polystyrene microspheres to the Ru-CORMs in step ② is (10-15):1; ③ Disperse the Ru-CORMs-coated micro-nanomotor in a 0.1 mol / L citrate buffer solution with a pH of 5, then add PEG-2000 polyethylene glycol and stir for 2 to 3 hours to obtain the modified micro-nanomotor. The mass fraction of the Ru-CORMs-coated micro-nanomotor in the modified micro-nanomotor described in step ③ is 1% to 3%, and the mass fraction of PEG-2000 polyethylene glycol is 1% to 2%; ④. Evenly mix the modified micro-nanomotors obtained in step ③ with polysulfone particles, dissolve them in N,N-dimethylformamide, and ultrasonically disperse them for 1 to 2 hours to obtain a modified solution; The mass fraction of the modified micro-nanomotors in the modification solution in step ④ is 5%, and the mass fraction of the polysulfone particles is 15%; ⑤. Scrape the modified liquid onto a glass plate with a thickness of 150 μm, then immerse it in a water coagulation bath for 10 seconds to form a porous membrane. After taking out the membrane, use anhydrous ethanol to replace the residual solvent, attach it to the surface of a commercial ultrafiltration ceramic membrane, and dry it at room temperature for 20 to 24 hours to obtain a CORMs functional membrane (6).

8. The method for synchronously preparing straw activated carbon and combustible gas by carbon-gas cogeneration according to claim 1, characterized in that The metal organic framework functional membrane (7) described in step 5 is copper-based or zinc-based, and the preparation method is as follows: ①. Ultrasonic cleaning of the commercial ultrafiltration ceramic membrane with hydrochloric acid, anhydrous ethanol and ultrapure water for 30 minutes respectively. Then, the cleaned commercial ultrafiltration ceramic membrane is immersed in an acidic solution or an alkaline solution for a period of time, and then taken out to obtain a pretreated ultrafiltration ceramic membrane; The preparation fraction of hydrochloric acid described in step ① is 3% to 5%; The acidic solution described in step ① is a mixture of H2SO4 and H2O2, wherein the volume ratio of H2SO4 to H2O2 is 3:1, the mass fraction of H2SO4 is 5%, and the mass fraction of H2O2 is 10%; The alkaline solution described in step ① is a mixed solution of ammonium persulfate and sodium hydroxide, wherein the mass fraction of ammonium persulfate is 2% and the mass fraction of sodium hydroxide is 5%; ② Dissolve the metal salt and organic ligand in water or anhydrous ethanol to obtain a metal salt-organic ligand solution; The metal salt described in step ② is zinc sulfate or copper sulfate; The organic ligand in step ② is trimesic acid, tetracarboxyphenylporphyrin or 2,3,6,7,10,11-hexahydroxytriphenyl; The concentration of the organic ligand in the metal salt-organic ligand solution in step ② is 5 mg / L, and the concentration of the metal salt is 2 mg / L; ③. Immerse the pretreated ultrafiltration ceramic membrane in a metal salt-organic ligand solution for 1 hour to 2 hours, then take it out and immerse it in a hypochlorous acid solution or hydrogen peroxide solution at a temperature of 60℃ to 80℃ for oxidation for 1 hour; The concentration of the hypochlorous acid solution in step ③ is 5%, and the concentration of the hydrogen peroxide solution is 10%; ④. Repeat step ③ 5 to 10 times, dry, and obtain a metal organic framework functional membrane (7).

9. Application of straw activated carbon prepared by the preparation method according to claim 1, characterized in that The straw activated carbon is used for adsorbing heavy metal ions in sewage.

10. The application of straw activated carbon according to claim 9, characterized in that The heavy metal ion in the sewage is Cd(Ⅱ).

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