Catalyst for catalytic oxidation of formaldehyde and preparation method thereof
Technical Field
The invention belongs to the field of chemical industry, relates to a material for purifying formaldehyde and a preparation method thereof, and particularly relates to a catalyst for catalyzing and oxidizing formaldehyde and a preparation method thereof.
Background
Formaldehyde (HCHO) is a common indoor air pollutant, and has various sources, mainly including various adhesive glues, various synthetic panels, wallpaper, coatings, foam materials, chemical fiber products, and the like. Formaldehyde has high toxicity, and chronic respiratory diseases are increased due to long-term contact or inhalation of low-concentration formaldehyde gas, and toxic symptoms comprise headache, neurasthenia, anxiety, dizziness, reduction of nervous system function and the like; the high-concentration formaldehyde has certain toxic action on human nervous system, liver, skin and immune system. More seriously, formaldehyde is carcinogenic. Therefore, the purification of formaldehyde is the key to ensure the cleanness of indoor air.
At present, an adsorption method is mostly adopted for removing formaldehyde gas, and commonly used adsorbents mainly comprise activated carbon, activated carbon fibers, molecular sieves, porous clay ores, silica gel and the like. The method has the advantages of simplicity, low cost and easy popularization; however, the adsorption method is limited by the capacity of the adsorbent, and the adsorbent only adsorbs formaldehyde but does not eliminate the formaldehyde, so that the adsorption method has poor effect in a high-temperature environment and causes secondary pollution. The catalytic oxidation method uses oxygen in the air as an oxidant, and can convert formaldehyde into harmless CO under the conditions of normal temperature and normal pressure 2 And H 2 O, the catalyst has a long service life, and the amount of the active component supported and the form of the catalyst can be controlled in consideration of the concentration of formaldehyde in the indoor air and the cost, which is an effective and practical technique. The key to the catalytic oxidation process is to find a catalyst that can maintain the long-term, high-efficiency decomposition of formaldehyde while maintaining high activity.
Catalysts for the catalytic oxidation of formaldehyde generally include noble metal catalysts and non-noble metal catalysts.
CN105289593A discloses a preparation method of micro-nano silver-loaded activated carbon for long-acting elimination of formaldehyde at room temperature, in the technology, a formaldehyde purification material is prepared by using ultrapure water cleaning and activated carbon treated by ammonia water as a carrier and loading micro-nano silver active components, and the formaldehyde purification material utilizes the adsorption and the reducibility of the activated carbon, the catalytic oxidation performance of the micro-nano silver on formaldehyde and an enrichment and conversion synergistic mechanism between the micro-nano silver and the activated carbon, so that the micro-nano silver-loaded activated carbon has high decomposition rate and stable performance of the catalytic oxidation of formaldehyde, but the silver application cost is high, and large-scale application is difficult to realize.
CN105435740A discloses a preparation method of a manganese dioxide-loaded activated carbon formaldehyde adsorbent, which comprises the steps of etching carbon on the surface of activated carbon by potassium permanganate to realize active carbon pore reconstruction, adjusting the pore structure and pore size of the surface of the activated carbon, improving the formaldehyde adsorption capacity, and enabling the formaldehyde adsorption amount of each gram of modified product to reach 195mg/g after being modified by loaded manganese dioxide.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a catalyst for catalytic oxidation of formaldehyde and a preparation method thereof, in the preparation method of the catalyst, active metal is introduced in the petroleum coke activation process, an activating agent enters a diffusion path generated by petroleum coke bulk phase, and is combined with amorphous carbon defects or graphite carbon sheet layers under the action of microwave catalysis to form a high-dispersion and stable-state structure, and the prepared catalyst has the advantages of good dispersion of active components, high degradation efficiency, high selectivity on formaldehyde and the like.
The invention provides a catalyst for catalyzing and oxidizing formaldehyde, which comprises an active component, an auxiliary agent and a carrier; the active component is Mn, the auxiliary agent is one or more of Mg, ba, zn, co, ti, cu, la and Ce, and preferably one or more of Co, cu and Ce; the carrier is petroleum coke-based activated carbon, wherein the content of the active component is 1-15%, preferably 3-12%, the content of the auxiliary agent is 1-10%, preferably 3-8%, and the content of the carrier is 76-97%, preferably 81-92%, based on the weight of the catalyst.
In the catalyst for catalyzing and oxidizing formaldehyde, the specific surface area of the catalyst is 1000-2800 m 2 A ratio of 1200 to 2500 m/g is preferred 2 /g。
In the catalyst for catalytic oxidation of formaldehyde, the active component is embedded into the amorphous defect of the petroleum coke-based active carbon and the active carbon graphite microchip layer, and the size of the active metal crystal grain is 1.1-6.3 nm, preferably 1.5-5 nm.
In a second aspect, the present invention provides a method for preparing a catalyst for catalytic oxidation of formaldehyde, the method comprising:
(1) Pretreating petroleum coke;
(2) Mixing the petroleum coke obtained in the step (1), an active metal-containing compound, an auxiliary agent-containing metal compound and an activating agent, and activating after uniformly mixing;
(3) Washing and drying the sample obtained in the step (2) to obtain a catalyst precursor A;
(4) Treating the catalyst precursor A by using an oxidizing solution, and drying to obtain a catalyst precursor B;
(5) And (3) treating the catalyst precursor B by using a coupling agent to obtain the catalyst for catalyzing and oxidizing the formaldehyde.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the pretreatment in the step (1) comprises the following steps:
(1.1) introducing ammonium phosphate salt into petroleum coke, and then drying;
(1.2) pretreating the sample obtained in the step (1.1) with water vapor-containing gas.
In the method, the ammonium phosphate salt in the step (1.1) is one or more of ammonium phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate, and is preferably ammonium phosphate.
In the above method, the method for introducing the ammonium phosphate salt into the petroleum coke in the step (1.1) is performed according to a method known in the art, and comprises one or more of an equal volume impregnation method, a supersaturated impregnation method and a kneading method, and is preferably a supersaturated impregnation method.
In the method, the drying temperature in the step (1.1) is 60-120 ℃, preferably the drying temperature is 80-100 ℃, the drying time is 2-8 h, preferably the drying time is 4-6 h; the drying is further preferably carried out under vacuum conditions.
In the method, the weight ratio of the ammonium phosphate salt to the petroleum coke in the step (1.1) is 0.1-1: 1, preferably 0.3 to 0.8.
In the above method, in step (1.2), the water vapor-containing gas is water vapor or a mixed gas of water vapor and a carrier gas, and the volume ratio of water vapor to carrier gas in the mixed gas is 1; the carrier gas is nitrogen or inert gas, and the inert gas is one or more of helium, neon, argon, krypton and xenon.
In the method, the pretreatment process in the step (1.2) comprises a first-stage pretreatment process, a second-stage pretreatment process and a cooling process, wherein the temperature of the first-stage pretreatment process is 150-250 ℃, preferably 180-220 ℃, and the pretreatment time is 1-6 hours, preferably 2-4 hours; the temperature of the second stage of pretreatment is 300-500 ℃, preferably 350-450 ℃, the pretreatment time is 1-6 h, preferably 2-4 h, and the second stage of pretreatment is cooled to 20-100 ℃, preferably 40-80 ℃ after the second stage of pretreatment is finished; the cooling process is preferably carried out under nitrogen protection.
In the method, the volume space velocity of the vapor-containing gas in the step (1.2) is 500 to 2000h -1 。
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the active metal-containing compound in the step (2) can be one or more of lithium permanganate, sodium permanganate, potassium permanganate and ammonium permanganate, and potassium permanganate is preferred.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the metal compound containing the auxiliary agent in the step (2) can be one or more of nitrate, sulfate and hydrochloride, preferably nitrate, specifically can be one or more of magnesium nitrate, barium nitrate, zinc nitrate, cobalt nitrate, titanium nitrate, copper nitrate, cerium nitrate and lanthanum nitrate, and preferably is one or more of cobalt nitrate, copper nitrate and cerium nitrate. The auxiliary agent is one or more of Mg, ba, zn, co, ti, cu, la and Ce, and preferably one or more of Co, cu and Ce.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the activating agent in the step (2) is one or more of potassium hydroxide, sodium hydroxide, potassium bicarbonate and sodium bicarbonate, and preferably potassium hydroxide.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the mass ratio of the active metal-containing compound (calculated by the mass of active metal elements), the auxiliary agent-containing metal compound (calculated by the mass of auxiliary agent metal oxides), the activator and the petroleum coke in the step (2) is 0.004-0.08: 0.004-0.06: 0.5 to 4:1, preferably 0.014 to 0.062:0.014 to 0.042:1 to 3:1.
in the preparation method of the catalyst for catalytic oxidation of formaldehyde, the activation process in the step (2) is as follows: uniformly mixing the petroleum coke obtained in the step (1), an active metal compound, an auxiliary agent-containing metal compound and an activating agent, heating to an activation temperature in a nitrogen or inert atmosphere, and cooling to 20-100 ℃ after activation for subsequent treatment, wherein the inert atmosphere is one or more of helium or argon; the activation temperature is 400-1000 ℃, preferably 700-900 ℃, and the activation time is 5-240 min, preferably 10-120 min. The activation process is further preferably carried out under the condition of microwave radiation, and the microwave frequency is 2450MHz or 915MHz; the microwave power is 1-10 kw, preferably 2-4 kw per kg of petroleum coke. When the activation is carried out under the microwave radiation condition, the method further preferably comprises two-stage activation, wherein the first stage is activated for 10 to 60min at 400 to 600 ℃ under the vacuum condition, inert gas or nitrogen is introduced to the atmosphere under the constant temperature condition, and the temperature is continuously increased to 700 to 900 ℃ under the microwave radiation condition for activation for 10 to 30min.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the washing in the step (3) is water washing, and the sample obtained in the step (2) is firstly mixed with deionized water, and after uniform mixing, solid-liquid separation is carried out until the pH value of the filtrate is neutral. The mass ratio of the sample obtained in the step (2) to the deionized water is 1.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the drying temperature in the step (3) is 100-200 ℃, preferably 120-180 ℃, and the drying time is 2-10 hours, preferably 4-8 hours. The drying is preferably carried out under vacuum conditions.
The preparation of the catalyst for catalyzing and oxidizing formaldehydeIn the method, the oxidizing solution in the step (4) contains HNO 3 、HClO、H 2 O 2 The concentration of the aqueous solution is 1 to 10 weight percent, preferably 1 to 5 weight percent; the process of treating the catalyst precursor A obtained in the step (3) with an oxidizing solution is as follows: mixing the catalyst precursor A with an oxidizing solution for 0.5-1 h, and then carrying out solid-liquid separation, wherein the mass ratio of the catalyst precursor A to the oxidizing solution is 1:5 to 1:30, preferably 1: 10-1: 20.
in the preparation method of the catalyst for catalytic oxidation of formaldehyde, the drying temperature in the step (4) is 100-200 ℃, preferably the drying temperature is 120-180 ℃, the drying time is 2-10 h, preferably the drying time is 4-8 h; the drying is preferably carried out under vacuum.
In the preparation method of the catalyst for catalytic oxidation of formaldehyde, the coupling agent in the step (5) can be one or more of dichlorodimethylsilane, trimethylchlorosilane, hexamethyldisilazane, aminopropyltriethoxysilane, methyltriethoxysilane and mercaptopropyltrimethoxysilane, and preferred is mercaptopropyltrimethoxysilane. The specific process for treating the catalyst precursor B by using the coupling agent in the step (5) is as follows: supersaturating ethanol solution containing coupling agent to impregnate catalyst precursor B, fully reacting for 1-3 h at 40-70 ℃, evaporating ethanol solution to dryness at 80-120 ℃, and roasting the obtained sample at 500-700 ℃ for 4-8 h in nitrogen atmosphere to obtain the catalyst for catalytic oxidation of formaldehyde. Wherein, in the ethanol solution containing the coupling agent, the mass ratio of the coupling agent to the ethanol is 1.
The third aspect of the present invention provides a catalyst for the catalytic oxidation of formaldehyde, which is obtained by the above-mentioned preparation method. The catalyst comprises an active component, an auxiliary agent and a carrier; the active component is Mn, the auxiliary agent is one or more of Mg, ba, zn, co, ti, cu, la and Ce, and preferably one or more of Co, cu and Ce; the carrier is petroleum coke-based activated carbon, wherein the content of active components is 1 to 15 percent, preferably 3 to 12 percent, and the content of auxiliaries is 1 to up to e, based on the weight of the catalyst10 percent, preferably 3 to 8 percent, and the content of the carrier is 76 to 97 percent, preferably 81 to 92 percent. In the catalyst for catalyzing and oxidizing formaldehyde, the specific surface area of the catalyst is 1000-2800 m 2 A ratio of 1200 to 2500 m/g is preferred 2 /g。
In the catalyst for catalyzing and oxidizing formaldehyde, the active component is embedded into the amorphous defects of the petroleum coke-based active carbon and the active carbon graphite microchip layer, and the size of the active metal crystal grain is 1.1-6.3 nm, preferably 1.5-5 nm.
The invention also provides the application of the catalyst in the catalytic oxidation reaction of formaldehyde. The formaldehyde catalytic oxidation reaction is carried out in a continuous flow fixed bed device, the raw material is the mixed gas of formaldehyde and air, the reaction pressure is normal pressure to 1atm, the total flow of the gas is 300 to 500mL/min, and the concentration of the formaldehyde is 50 to 500ppm.
Compared with the prior art, the catalyst for catalyzing and oxidizing formaldehyde and the preparation method thereof have the following advantages:
1. according to the preparation method of the catalyst for catalytic oxidation of formaldehyde, active metal and auxiliary agent are introduced in the petroleum coke activation process, the active agent enters a diffusion path generated by petroleum coke phase, and is combined with amorphous carbon defects or graphite carbon sheet layers under the action of microwave catalysis to form a high-dispersion and stable-state structure.
2. According to the preparation method of the catalyst for catalytic oxidation of formaldehyde, an active metal precursor is introduced in the petroleum coke activation process, so that active metal molecules can be better dispersed in a molten state activator, and the active metal is further promoted to enter the petroleum coke; when the active metal precursor exists in an acid radical form, the active metal precursor can more easily enter the petroleum coke-based active carbon. The reason is that under the action of an activator, active sites of petroleum coke react to generate positive charged cavities, and acid radical anions are more easily combined and intercalated.
3. The preparation method of the catalyst for catalytic oxidation of formaldehyde comprises the steps of pretreating petroleum coke, introducing ammonium phosphate into the petroleum coke, and then carrying out two-stage treatment on the petroleum coke by using steam-containing gas, so that the ammonium phosphate is promoted to be decomposed in the petroleum coke to generate ammonia gas and phosphoric acid, the generated ammonia gas provides more primary pores for further activation of the petroleum coke, and meanwhile, the generated phosphoric acid can also be used as an activating agent for carrying out primary activation on the petroleum coke to create a developed pore structure and reduce the consumption of a subsequent alkali activating agent, so that the production cost is low, and the environmental pollution is small. Solves the problems that the petroleum coke used has compact structure, high crystallinity and lacks of primary pores required by activation, and needs to be activated to form pores by strong alkali with the alkali-coke ratio of more than 3/1 in inert atmosphere, which causes serious corrosion of equipment and higher production cost and restricts the development and application of the petroleum coke.
4. In the catalyst for catalytic oxidation of formaldehyde and the preparation method thereof, the raw materials used by the catalyst are cheap and easy to obtain, the preparation method is simple, formaldehyde can be converted into harmless carbon dioxide and water through low-temperature catalytic oxidation, and secondary pollution is avoided. The coupling agent is adopted to treat the catalyst precursor, so that the hydrophobicity of the activated carbon carrier is effectively improved, the desorption of product water from the carrier is accelerated, the catalytic oxidation reaction is promoted, and the catalyst is not easy to inactivate. In the catalyst, the active metal is highly dispersed on the surface of the carrier, and is not easy to agglomerate in the reaction process, so that the anti-sintering capability is improved, and the catalytic reaction capability of the catalyst on formaldehyde is enhanced.
Detailed Description
The following examples are provided to further illustrate the technical solutions of the present invention, but the present invention is not limited to the following examples.
The specific surface and pore size distribution of the catalyst in the following examples and comparative examples are shown by using low temperature N 2 Measuring by an adsorption method; the grain size of the active component of the catalyst is measured by an X-ray broadening method.
Example 1
Weighing 50g of ammonium phosphate, and dissolving the ammonium phosphate in 200mL of deionized water to obtain a solution A; grinding 100g petroleum coke into powder, adding into the solution A, standing for 1.5h, filtering, and drying the obtained solid sample in an oven at 110 deg.CAnd 5h. Pretreating the dried solid sample with water vapor at 200 deg.C for 3h (volume space velocity of water vapor gas is 800 h) -1 ) And then raising the temperature to 400 ℃, continuing to pretreat for 3h, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, then uniformly mixing with 16.18g of potassium permanganate, 9.87g of cobalt nitrate and 300g of potassium hydroxide, placing in a tube furnace, and heating to 800 ℃ in nitrogen atmosphere for activation for 40min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
The obtained catalyst precursor B was weighed and mixed in a mass ratio of 1:15 and 3wt% of H 2 O 2 And mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
The catalyst precursor C is supersaturated and impregnated by an ethanol solution of mercaptopropyltrimethoxysilane (the mass ratio of the mercaptopropyltrimethoxysilane to the ethanol is 1: 30), and after the catalyst precursor C fully reacts for 2 hours at the temperature of 60 ℃, evaporating the ethanol solution to dryness at 100 deg.C, calcining the sample at 600 deg.C under nitrogen atmosphere for 6h to obtain a dry mass fraction of 10% Mn, 5% Co 2 O 3 The catalyst of (4), noted C-1.
Example 2
Weighing 50g of ammonium phosphate, and dissolving the ammonium phosphate in 200mL of deionized water to obtain a solution A; 100g of petroleum coke was ground to a powder, then added to solution A, left to stand for 1.5h, then filtered, and the resulting solid sample was dried in an oven at 110 ℃ for 5h. Pretreating the dried solid sample with water vapor at 200 deg.C for 3h (volume space velocity of water vapor gas is 800 h) -1 ) And then raising the temperature to 400 ℃, continuing to pretreat for 3h, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, then uniformly mixing with 16.18g of potassium permanganate, 8.56g of copper nitrate and 300g of potassium hydroxide, placing in a microwave heating furnace with microwave frequency of 2450MHz, and heating to 800 ℃ under the condition of microwave power of 0.3kw and activating for 40min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
The obtained catalyst precursor B was weighed and mixed in a mass ratio of 1:15 and 3wt% of H 2 O 2 And mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
The catalyst precursor C is supersaturated and impregnated with an ethanol solution of mercaptopropyltrimethoxysilane (the mass ratio of mercaptopropyltrimethoxysilane to ethanol is 1: 30), the mixture is fully reacted at 60 ℃ for 2 hours, the ethanol solution is evaporated at 100 ℃, the obtained sample is roasted at 600 ℃ for 6 hours in a nitrogen atmosphere, and the catalyst with the mass accounting for 10% of Mn and 5% of CuO in the adsorbent is prepared and recorded as C-2.
Example 3
Weighing 50g of ammonium phosphate, and dissolving the ammonium phosphate in 200mL of deionized water to obtain a solution A; 100g of petroleum coke was ground to a powder, then added to solution A, left to stand for 1.5h, then filtered, and the resulting solid sample was dried in an oven at 110 ℃ for 5h. Pretreating the dried solid sample with water vapor at 200 deg.C for 3h (volume space velocity of water vapor gas is 800 h) -1 ) And raising the temperature to 400 ℃, continuing to pretreat for 3 hours, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, uniformly mixing with 16.18g of potassium permanganate, 7.10g of cerium nitrate and 300g of potassium hydroxide, placing in a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 500 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 40min, introducing nitrogen to the normal pressure, and continuously heating to 800 ℃ under the condition that the microwave power is 0.3kw for activation for 20min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
The obtained catalyst precursor B was weighed and mixed in a mass ratio of 1:15 and 3wt% of H 2 O 2 And mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
Supersaturating and dipping the catalyst precursor C by adopting ethanol solution of mercaptopropyltrimethoxysilane (the mass ratio of the mercaptopropyltrimethoxysilane to the ethanol is 1: 30), fully reacting for 2 hours at 60 ℃, evaporating the ethanol solution to dryness at 100 ℃, roasting the obtained sample for 6 hours at 600 ℃ in nitrogen atmosphere, and finally obtaining the catalyst precursor C with the mass accounting for 10 percent of the adsorbent, wherein the mass of the catalyst precursor C accounts for 5 percent of the content of the CeO and the mass of the CeO 5 2 The catalyst of (4), noted C-3.
Example 4
Weighing 50g of ammonium phosphate, and dissolving the ammonium phosphate in 200mL of deionized water to obtain a solution A; 100g of petroleum coke is ground into powder, then added into the solution A, placed for 1.5h and then filtered, and the solid sample obtained is dried in an oven at 110 ℃ for 5h. Pretreating the dried solid sample with water vapor at 200 deg.C for 3h (volume space velocity of water vapor gas is 500 h) -1 ) And then raising the temperature to 400 ℃, continuing to pretreat for 3h, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, then uniformly mixing the powder with 7.89g of potassium permanganate, 4.15g of cerium nitrate and 300g of sodium hydroxide, putting the mixture into a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 600 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 20min, then introducing nitrogen to the normal pressure, and continuously heating to 900 ℃ under the condition that the microwave power is 0.3kw to activate for 10min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
Weighing the obtained catalyst precursor B, and mixing the weighed catalyst precursor B with the catalyst precursor B according to a mass ratio of 1:15 and 3wt% of H 2 O 2 And (3) mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
The catalyst precursor C is supersaturated and impregnated with an ethanol solution of mercaptopropyltrimethoxysilane (the mass ratio of the mercaptopropyltrimethoxysilane to the ethanol is 1: 30), fully reacted at 60 ℃ for 2 hours, the ethanol solution is evaporated at 100 ℃, the obtained sample is roasted at 600 ℃ for 6 hours in a nitrogen atmosphere, and the active carbon adsorbent is prepared, wherein the mass of the active carbon adsorbent accounts for 5 percent of Mn and 3 percent of CeO 2 The catalyst of (4), noted C-4.
Example 5
Weighing 50g of ammonium phosphate, and dissolving the ammonium phosphate in 200mL of deionized water to obtain a solution A; 100g of petroleum coke is ground into powder, then added into the solution A, placed for 1.5h and then filtered, and the solid sample obtained is dried in an oven at 110 ℃ for 5h. Pretreating the dried solid sample with water vapor at 200 deg.C for 3h (the volume space velocity of water vapor gas is 1200 h) -1 ) And raising the temperature to 400 ℃, continuing to pretreat for 3 hours, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, uniformly mixing with 25.22g of potassium permanganate, 11.79g of cerium nitrate, 100g of potassium hydroxide and 200g of potassium bicarbonate, placing in a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 400 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 60min, introducing nitrogen to the normal pressure, and continuously heating to 700 ℃ under the condition that the microwave power is 0.3kw for activation for 30min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
The obtained catalyst precursor B was weighed and mixed in a mass ratio of 1:15 and 3wt% of H 2 O 2 And (3) mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
Supersaturating and dipping a catalyst precursor C by adopting an ethanol solution of mercaptopropyltrimethoxysilane (the mass ratio of the mercaptopropyltrimethoxysilane to the ethanol is 1: 30), fully reacting at 60 ℃ for 2 hours, evaporating the ethanol solution at 100 ℃, roasting the obtained sample at 600 ℃ for 6 hours in a nitrogen atmosphere, and thus obtaining the catalyst precursor C with the mass percentage of 15% of CeO Mn and 8% of CeO in the adsorbent 2 The catalyst of (4), noted C-5.
Example 6
Weighing 50g of ammonium dihydrogen phosphate, and dissolving in 200mL of deionized water to obtain a solution A; 100g of petroleum coke is ground into powder, then added into the solution A, placed for 1.5h and then filtered, and the solid sample obtained is dried in an oven at 110 ℃ for 5h. And (2) pretreating the dried solid sample for 3h at 200 ℃ by using a mixed gas with the volume ratio of water vapor to nitrogen being 1 -1 ) And raising the temperature to 400 ℃, continuing to pretreat for 3 hours, and then cooling to 60 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, uniformly mixing with 16.18g of potassium permanganate, 7.10g of cerium nitrate and 300g of potassium hydroxide, placing in a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 500 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 40min, introducing nitrogen to the normal pressure, and continuously heating to 800 ℃ under the condition that the microwave power is 0.3kw for activation for 20min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
Weighing the obtained catalyst precursor B, and mixing the weighed catalyst precursor B with the catalyst precursor B according to a mass ratio of 1:20 and 1wt% HNO 3 And (3) mixing the aqueous solutions, fully stirring for 0.5h, then carrying out solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under a vacuum condition to obtain a catalyst precursor C.
The catalyst precursor C is supersaturated and impregnated with an ethanol solution of methyltriethoxysilane (the mass ratio of methyltriethoxysilane to ethanol is 1 2 The catalyst of (4), denoted as C-6.
Example 7
Weighing 50g of ammonium hydrogen phosphate, and dissolving in 200mL of deionized water to obtain a solution A; 100g of petroleum coke is ground into powder, then added into the solution A, placed for 1.5h and then filtered, and the solid sample obtained is dried in an oven at 90 ℃ for 8h. And (2) pretreating the dried solid sample for 3h at 200 ℃ by using a mixed gas with the volume ratio of water vapor to argon gas being 1 -1 ) And then raising the temperature to 400 ℃, continuing to pretreat for 3 hours, and then cooling to 40 ℃ under the protection of nitrogen to obtain the pretreated petroleum coke.
Grinding the petroleum coke into powder, then uniformly mixing with 16.18g of potassium permanganate, 7.10g of cerium nitrate and 300g of potassium hydroxide, placing the mixture in a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 500 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 40min, then introducing nitrogen to the normal pressure, and continuously heating to 800 ℃ under the condition that the microwave power is 0.3kw to activate for 20min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6 hours under a vacuum condition to obtain a catalyst precursor B.
The obtained catalyst precursor B was weighed and mixed in a mass ratio of 1: mixing 10 with 5wt% HClO aqueous solution, stirring thoroughly for 1h, performing solid-liquid separation, placing the obtained solid sample in a vacuum drying oven, and drying at 150 ℃ for 6h under vacuum condition to obtain catalyst precursor C.
The catalyst precursor C was supersaturated and impregnated with an ethanol solution of hexamethyldisilazane (the mass ratio of hexamethyldisilazane to ethanol was 1 2 The catalyst of (4), noted C-7.
Comparative example
Grinding 100g of petroleum coke into powder, then uniformly mixing the powder with 300g of potassium hydroxide, placing the mixture into a microwave heating furnace with microwave frequency of 2450MHz, vacuumizing, heating to 500 ℃ under the condition that the microwave power is 0.3kw, keeping the temperature constant for 40min, then introducing nitrogen to normal pressure, and continuing heating to 800 ℃ under the condition that the microwave power is 0.3kw to activate for 20min.
Grinding the activated sample into powder, weighing, and mixing the powder according to a mass ratio of 1:15 and deionized water, fully stirring, then carrying out solid-liquid separation until the pH value of the filtrate is neutral, placing the obtained solid sample in a vacuum drying oven, and drying for 6 hours at 150 ℃ under the vacuum condition.
Weighing 16.18g of potassium permanganate and 7.10g of cerous nitrate, dissolving the potassium permanganate and the cerous nitrate in 100mL of deionized water, adding the mixture into the sample obtained in the step of vacuum drying, uniformly stirring, aging for 2 hours, then placing the sample into a vacuum drying oven, drying the sample for 6 hours at 150 ℃ under a vacuum condition, roasting the dried sample for 6 hours at 700 ℃ under a nitrogen atmosphere, and thus obtaining the catalyst with the weight percentage content of 10% of Mn and 5% of CeO 2 The catalyst of (4), denoted as D-1.
Evaluation conditions were as follows: the formaldehyde catalytic oxidation reaction is carried out in a continuous flow fixed bed device, the raw material is a mixed gas of formaldehyde and air with the concentration of 220ppm, the reaction pressure is normal pressure, the temperature is room temperature, the total flow of the gas is 400mL/min, the point of 10h of reaction is taken for analysis, and the reaction results are shown in Table 1.
TABLE 1 catalyst Properties and reaction Performance