阅读说明：本技术 一种去除可挥发性有机物催化剂及制备方法 (Catalyst for removing volatile organic compounds and preparation method thereof ) 是由 郭明星 张喆 黄均妍 尹淑慧 于 2021-08-06 设计创作，主要内容包括：本发明公开了一种去除可挥发性有机物催化剂及制备方法,通过将钴盐和铝盐用75％～87.5％的乙醇溶解后,搅拌并依次加入碳酸钾和柠檬酸使其完全溶解,得到前驱液；将前驱液边加热边搅拌后,干燥,得到前驱体；前驱体经研磨后焙烧,压片,得到去除可挥发性有机物催化剂。本发明的一种去除可挥发性有机物催化剂及制备方法,该催化剂当K-(2)CO-(3)的掺杂量为15％时,催化剂对乙苯的转化率达到90％,此时所需的测试温度最低,只需194℃。随着K-(2)CO-(3)掺杂量的增加,K-(2)CO-(3)/CoAl-(2)O-(4)催化剂对乙苯的催化活性表现出先升高后降低的趋势,其中,15％K-(2)CO-(3)/CoAl-(2)O-(4)对目标污染物乙苯表现出最好的催化活性和氧化还原性。(The invention discloses a catalyst for removing volatile organic compounds and a preparation method thereof, which comprises the steps of dissolving cobalt salt and aluminum salt by using 75-87.5% of ethanol, stirring, and sequentially adding potassium carbonate and citric acid to completely dissolve the cobalt salt and the aluminum salt to obtain a precursor solution; heating and stirring the precursor solution, and drying to obtain a precursor; grinding the precursor, roasting, and tabletting to obtain the volatile organic matter removing catalyst. The invention relates to a catalyst for removing volatile organic compounds and a preparation method thereof, wherein the catalyst is K 2 CO 3 When the doping amount of the catalyst is 15 percent, the conversion rate of the catalyst to ethylbenzene is up toTo 90%, the required test temperature is minimum at 194 ℃. With K 2 CO 3 Increase in doping amount, K 2 CO 3 /CoAl 2 O 4 The catalytic activity of the catalyst on ethylbenzene shows a tendency of increasing and then decreasing, wherein the K is 15 percent 2 CO 3 /CoAl 2 O 4 The catalyst shows the best catalytic activity and oxidation reduction performance on the target pollutant ethylbenzene.)

1. The preparation method of the catalyst for removing the volatile organic compounds is characterized by comprising the following steps:

s1: dissolving cobalt salt and aluminum salt with 75-87.5% ethanol, stirring, and sequentially adding potassium carbonate and citric acid to completely dissolve to obtain a precursor solution;

s2: heating and stirring the precursor liquid in the step S1, and drying to obtain a precursor;

s3: and (4) grinding the precursor in the step S2, roasting, and tabletting to obtain the volatile organic compound removal catalyst.

2. The method as claimed in claim 1, wherein in step S1, the cobalt salt is one of cobalt acetate, cobalt chloride, cobalt nitrate and cobalt acetylacetonate; the aluminum salt is one of aluminum nitrate, aluminum sulfate and aluminum chloride.

3. The method of claim 2, wherein in step S1, the cobalt salt is cobalt nitrate and the aluminum salt is aluminum nitrate.

4. The method of claim 1, wherein in step S1, the molar ratio of the cobalt salt to the aluminum salt is 1-3: 1-6, wherein the mass ratio of the potassium carbonate is 0.05-0.2, and the molar ratio of the citric acid to the metal ions in the precursor liquid is 1-3: 1 to 6.

5. The method according to claim 1, wherein in step S2, the heating temperature is 60-100 ℃, and the stirring time is 5-10 h; the drying is drying, the drying temperature is 70-120 ℃, and the drying time is 12-48 h.

6. The method of claim 1, wherein in step S3, the calcination temperature is 500-900 ℃ and the calcination time is 4-8 h.

7. The catalyst for removing the volatile organic compounds is characterized by being prepared by the preparation method of the catalyst for removing the volatile organic compounds as claimed in claims 1-6.

Technical Field

The invention relates to the technical field of catalysts for energy utilization and environmental protection, in particular to a catalyst for removing volatile organic compounds and a preparation method thereof.

Background

VOCs, i.e., volatile organic compounds, refer to organic compounds having a saturated vapor pressure of greater than 133.32Pa at room temperature and a boiling point of 260 ℃ or lower at atmospheric pressure, or any organic solid or liquid that is volatile at room temperature and atmospheric pressure. Most VOCs have strong toxicity, can damage blood and cardiovascular systems of human bodies, cause various diseases, cause metabolic defects, and have the harm of carcinogenesis, teratogenesis and mutagenesis to human bodies. The chemical properties of VOCs are such that under certain environmental conditions, photochemical reactions may occur to form photochemical smog and secondary pollutants, which are even more harmful than the primary pollutants and seriously threaten the ecological environment.

VOCs are removed by a variety of methods including combustion, condensation, absorption, adsorption, biological, catalytic oxidation, and the like. Wherein the catalytic oxidation method has the characteristics of environmental protection, wide application and capability of generating CO by reaction under mild conditions₂And H₂And O. This method does not produce secondary pollution and can be reacted at low temperature, which is considered to be the most promising and suitable method for eliminating VOCs.

The key point of the catalytic oxidation method is the selection of the catalyst, so far, the catalyst for catalytically oxidizing organic pollutants mainly comprises a perovskite composite oxide catalyst (non-noble metal oxide catalyst) and a noble metal supported catalyst, the preparation cost of the catalyst is lower, but the catalytic performance and the stability performance are poorer; the metal catalyst or the metal oxide catalyst is mostly high in cost, or relatively poor in catalytic performance and quick in inactivation, and the noble metal is easy to volatilize and sinter and is high in cost; in addition, the removal of halogen-containing VOCs can result in rapid catalyst deactivation. Therefore, how to prepare a catalyst with simple preparation process, low cost, stable performance and high catalytic efficiency is a technical problem to be solved at present.

Disclosure of Invention

The invention provides a catalyst for removing volatile organic compounds and a preparation method thereof, which aim to solve the problems of low efficiency and high cost of the existing catalyst.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the preparation method of the catalyst for removing the volatile organic compounds is characterized by comprising the following steps:

s1: dissolving cobalt salt and aluminum salt with 75-87.5% ethanol, stirring, and sequentially adding potassium carbonate and citric acid to completely dissolve to obtain a precursor solution;

s2: heating and stirring the precursor liquid in the step S1, and drying to obtain a precursor;

s3: and (4) grinding the precursor in the step S2, roasting, and tabletting to obtain the volatile organic compound removal catalyst.

Further, in the step S1, the cobalt salt is one of cobalt acetate, cobalt chloride, cobalt nitrate, and cobalt acetylacetonate; the aluminum salt is one of aluminum nitrate, aluminum sulfate and aluminum chloride.

In step S1, the cobalt salt is cobalt nitrate, and the aluminum salt is aluminum nitrate.

Further, in the step S1, the molar ratio of the cobalt salt to the aluminum salt is 1 to 3: 1-6, wherein the mass ratio of the potassium carbonate is 0.05-0.2, and the molar ratio of the citric acid to the metal ions in the precursor liquid is 1-3: 1 to 6.

Further, in the step S2, the heating temperature range of the heating is 60-100 ℃, and the stirring time is 5-10 hours; the drying is drying, the drying temperature is 70-120 ℃, and the drying time is 12-48 h.

Further, in the step S3, the roasting temperature is 500-900 ℃ and the time is 4-8 h.

The catalyst for removing the volatile organic compounds is prepared by a preparation method of the catalyst for removing the volatile organic compounds.

The invention relates to a catalyst for removing volatile organic compounds and a preparation method thereof, wherein the catalyst is K₂CO₃When the doping amount is 15%, the conversion rate of the catalyst to ethylbenzene reaches 90%, and the required test temperature is the lowest and only needs 194 ℃. With K₂CO₃Increase in doping amount, K₂CO₃/CoAl₂O₄The catalytic activity of the catalyst on ethylbenzene shows a tendency of increasing and then decreasing, wherein the K is 15 percent₂CO₃/CoAl₂O₄The catalyst shows the best catalytic activity and oxidation reduction performance on the target pollutant ethylbenzene.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 shows xK of the present invention₂CO₃/CoAl₂O₄A catalyst activity evaluation chart;

FIG. 2 shows xK₂CO₃/CoAl₂O₄H of catalyst₂-a TPR map.

In the figure, xK₂CO₃/CoAl₂O₄For removing volatile organic catalyst, x is K in catalyst₂CO₃Mass fraction of (c).

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The catalyst for removing volatile organic compounds prepared by the invention is marked as xK₂CO₃/CoAl₂O₄(x represents K in the catalyst)₂CO₃Mass fraction) of the catalyst prepared by the invention, the evaluation method of the catalyst prepared by the invention is as follows: filling 20-40 mesh catalyst with the same mass in a constant temperature area of a fixed bed stainless steel reaction tube (the upper part and the lower part are filled with quartz wool), introducing nitrogen after leakage test, wherein the nitrogen is used as carrier gas to bring ethylbenzene as a target pollutant into a catalytic oxidation reactor for catalytic reaction, detecting the content of a product after catalysis by using a gas chromatograph GC-7900, and calculating the ethylbenzene conversion rate by the ratio of the reduction amount of the peak area before and after reaction to the peak area before reaction. The technological parameters are the temperature rising speed of 10 ℃/min, the airspeed of 6000h-¹The flow rate of the reaction gas was 20mL/min, and the temperature of the detector FID was 200 ℃. The catalysts of examples 1 to 5 of the present invention were evaluated by the same methods as those of the evaluation methods.

Removal of volatile organic catalysts in examples 1-5 xK was prepared as follows₂CO₃/CoAl₂O₄Preparation of xK by catalyst (1)₂CO₃/CoAl₂O₄The precursor solution is converted into a precursor by a sol-gel method, and the prepared precursor is roasted and tabletted to form the target catalyst.

Example 1:

8.73g of cobalt nitrate hexahydrate, 22.51g of aluminum nitrate nonahydrate and 34.59g of citric acid were dissolved in 300ml of 87.5% ethanol. And fully stirring the prepared mixed solution in a water bath kettle at 70 ℃ for 5 hours to obtain a precursor solution. And then the prepared precursor solution is put into an oven with the temperature of 100 ℃ for drying for 36h to obtain the precursor. Finally, grinding the prepared precursor into powderHeating to 700 deg.C at a rate of 5 deg.C/min in a muffle furnace, calcining at 700 deg.C in air atmosphere for 4 hr, and tabletting with a tabletting machine of 18Mpa to obtain 20-40 mesh CoAl₂O₄Catalyst, labeled cat.1.

Example 2:

8.73g of cobalt nitrate hexahydrate, 22.51g of aluminum nitrate nonahydrate, 0.265g of potassium carbonate and 34.59g of citric acid were dissolved in 300ml of 87.5% ethanol. And fully stirring the prepared mixed solution in a water bath kettle at 70 ℃ for 5 hours to obtain a precursor solution. And then the prepared precursor solution is put into an oven with the temperature of 100 ℃ for drying for 36h to obtain the precursor. Finally, grinding the prepared precursor into powder, heating to 700 ℃ at a heating rate of 5 ℃/min in a muffle furnace, roasting at 700 ℃ for 4h in an air atmosphere, and tabletting by using a tabletting machine with the pressure of 18Mpa to obtain 5% K of 20-40 meshes₂CO₃/CoAl₂O₄Catalyst, labeled cat.2.

Example 3:

8.73g of cobalt nitrate hexahydrate, 22.51g of aluminum nitrate nonahydrate, 0.53g of potassium carbonate and 34.59g of citric acid were dissolved in 300ml of 87.5% ethanol. And fully stirring the prepared mixed solution in a water bath kettle at 70 ℃ for 5 hours to obtain a precursor solution. And then the prepared precursor solution is put into an oven with the temperature of 100 ℃ for drying for 36h to obtain the precursor. Finally, grinding the prepared precursor into powder, heating to 700 ℃ at a heating rate of 5 ℃/min in a muffle furnace, roasting for 4h at 700 ℃ in air atmosphere, and tabletting by using a tabletting machine with the pressure of 18Mpa to obtain 20-40 meshes of 10% K₂CO₃/CoAl₂O₄Catalyst, labeled cat.3.

Example 4:

8.73g of cobalt nitrate hexahydrate, 22.51g of aluminum nitrate nonahydrate, 0.796g of potassium carbonate and 34.59g of citric acid were dissolved in 300ml of 87.5% ethanol. And fully stirring the prepared mixed solution in a water bath kettle at 70 ℃ for 5 hours to obtain a precursor solution. And then the prepared precursor solution is put into an oven with the temperature of 100 ℃ for drying for 36h to obtain the precursor. Finally, grinding the prepared precursor into powder, heating to 700 ℃ at a heating rate of 5 ℃/min in a muffle furnace, and baking at 700 ℃ in an air atmosphereBurning for 4 hr, and tabletting with a tabletting machine of 18Mpa to obtain 20-40 mesh 15% K₂CO₃/CoAl₂O₄Catalyst, labeled cat.4.

Example 5:

8.73g of cobalt nitrate hexahydrate, 22.51g of aluminum nitrate nonahydrate, 1.06g of potassium carbonate and 34.59g of citric acid were dissolved in 300ml of 87.5% ethanol. And fully stirring the prepared mixed solution in a water bath kettle at 70 ℃ for 5 hours to obtain a precursor solution. And then the prepared precursor solution is put into an oven with the temperature of 100 ℃ for drying for 36h to obtain the precursor. Finally, grinding the prepared precursor into powder, heating to 700 ℃ at a heating rate of 5 ℃/min in a muffle furnace, roasting for 4h at 700 ℃ in air atmosphere, and tabletting by using a tabletting machine with the pressure of 18Mpa to obtain 20-40 meshes of 20% K₂CO₃/CoAl₂O₄Catalyst, labeled cat.5.

Examples 1 to 5, different K₂CO₃The effect of the doping amount on the specific surface area of the catalyst is shown in Table 1, when K is₂CO₃Respectively, 0%, 5%, 10%, 15% and 20% and corresponding specific surface areas of respectively 62.50m²·g^-1、70.10m²·g^-1、77.35m²·g^-1、88.36m²·g^-1And 84.60m²·g^-1It is clear that K is₂CO₃The specific surface area of the catalyst is increased when the doping amount is increased, and when K is₂CO₃When the doping amount of (A) is 0 to 15%, the specific surface area of the catalyst is gradually increased, probably because K is₂CO₃The doping affects the symmetry of crystal lattices, thereby inhibiting the growth of crystals and enabling the catalyst to be closer to an amorphous state. Therefore, the prepared catalyst has larger specific surface area. When K is₂CO₃When the doping amount of (C) is 20% (Cat.5), the specific surface area of the catalyst is reduced, and excessive K is doped to cause lattice distortion of the catalyst, so that the specific surface area is reduced. In most cases, the larger the specific surface area is, the more reactive sites of the catalyst are, and the better the catalytic activity of the catalyst is, which is shown in the specification of the catalystThe conversion rate of ethylbenzene is higher during the reaction, so that when K is used₂CO₃When the doping amount of (2) is 15%, the specific surface area of the catalyst is the largest, and the catalyst has high catalytic activity.

Table 1: different K₂CO₃Effect of doping amount on specific surface area of catalyst

Catalyst and process for preparing same	K2CO3Doping amount/%)	Specific surface area/m2·g-1
			Cat.1	0	62.50
Cat.2	5	70.10
			Cat.3	10	77.35
Cat.4	15	88.36
			Cat.5	20	84.60

As shown in FIG. 1, it can be seen from the evaluation of the catalysts of examples 1 to 5 that Cat.4 of example 4 has the best catalytic effect, and K is the best when₂CO₃Is 15% by mass, the lowest test temperature required for 90% conversion of the catalyst to ethylbenzene is 194 ℃, whereas K is the same as in examples 1, 2, 3 and 5₂CO₃The temperatures at which the corresponding conversions reached 90% (T90) were 311 deg.C, 262 deg.C, 238 deg.C and 210 deg.C, respectively, at mass fractions of 0%, 5%, 10% and 20%, respectively, thus making it possible to demonstrate that when K is present₂CO₃When the mass fraction of (A) is 15%, the modulation effect of K on the catalyst is the best. Different K₂CO₃Mass fraction of CoAl₂O₄The spinel catalyst exhibits a catalytic activity sequence for ethylbenzene of: 15% K₂CO₃/CoAl₂O₄＞20％K₂CO₃/CoAl₂O₄＞10％K₂CO₃/CoAl₂O₄＞5％K₂CO₃/CoAl₂O₄＞CoAl₂O₄With K₂CO₃Increase in doping amount, K₂CO₃/CoAl₂O₄The catalytic activity of the catalyst on ethylbenzene shows a tendency of increasing and then decreasing, wherein the K is 15 percent₂CO₃/CoAl₂O₄Shows the best catalytic activity to the target pollutant ethylbenzene.

It can be seen from FIG. 2 that the first peak position lies between 250 ℃ and 500 ℃ and that in this temperature interval 10% K₂CO₃/CoAl₂O₄(Cat.3)，15％K₂CO₃/CoAl₂O₄(Cat.4) and 20% K₂CO₃/CoAl₂O₄(Cat.5) three groups of catalyst samples all produced reduction peaks, and in this case, the reduction peaks should be due to Co₃O₄Of (5) Co³⁺Is reduced to Co²⁺Produced when K₂CO₃At a doping level of 5% (Cat.2), no significant reduction peak was observed in this temperature interval, probably because the doping level of K was low and the incorporation into the catalyst lattice occurredBecause of the dispersion, the Co does not greatly affect the A site of the catalyst, and Co is not produced or is produced in a very small amount in the catalyst₃O₄Therefore at H₂The reduction peak generated by the test can not be obviously detected, the second peak position is between 550 and 700 ℃, and at the moment, Co₃O₄And CoAl₂O₄Of (5) Co²⁺Is reduced, wherein, when K₂CO₃At a doping amount of 15% (cat.4), the reduction peak becomes broad and splits into two peaks, and since the interaction between K and Al occurs, the chemical bond between cobalt and aluminum is weakened to some extent, so that more Co is released. At the same time, with K₂CO₃The reduction peak gradually shifted toward a low temperature direction with an increase in the doping amount, and it was confirmed that in this interval, as K increased₂CO₃The catalyst becomes easier to be reduced and the redox performance of the catalyst is better due to the increase of the doping amount. When K is₂CO₃When the doping amount reaches 20% (Cat.5), the reduction peak starts to move in the high temperature direction, and the redox performance of the catalyst starts to be lowered, possibly due to lattice distortion or micropore blockage of the catalyst caused by excessive K doping, so that the redox performance of the catalyst is lowered, and therefore, when K is added₂CO₃When the doping amount of the catalyst is 15 percent (Cat.4), the catalyst has better oxidation-reduction performance.

The invention relates to a catalyst for removing volatile organic compounds and a preparation method thereof, wherein the catalyst is K₂CO₃When the doping amount is 15%, the conversion rate of the catalyst to ethylbenzene reaches 90%, and the required test temperature is the lowest and only needs 194 ℃. With K₂CO₃Increase in doping amount, K₂CO₃/CoAl₂O₄The catalytic activity of the catalyst on ethylbenzene shows a tendency of increasing and then decreasing, wherein the K is 15 percent₂CO₃/CoAl₂O₄The catalyst shows the best catalytic activity and oxidation reduction performance on the target pollutant ethylbenzene.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.