Microwave response catalytic material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalysts, and particularly provides a microwave response catalytic material, the chemical composition of which is CoaMnbOx, wherein the ratio of a to b is (2: 1)-(1: 2), and x is 2-4. According to the microwave response catalytic material, dual adjustment of microwave absorption characteristics and catalytic performance is achieved by regulating metal ions, meanwhile, MOF-derived porous metal oxide has a porous structure and a high surface area ratio, adsorption and catalytic oxidation reaction of VOCs are facilitated, the situation that a traditional supported catalyst uses carriers such as activated carbon for improving the adsorption performance is avoided, and the service life of the catalyst is prolonged. The stability of the catalyst is favorably improved. Based on the catalytic material, the invention further provides a VOCs adsorption-microwave catalytic oxidation system, and based on the strong adsorption and rapid microwave heating characteristics of the porous metal oxide derived from the metal organic framework, compared with traditional thermocatalysis, the reaction time is shorter, and the energy efficiency is higher.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a microwave response catalytic material and a preparation method and application thereof. BACKGROUND

[0002] Volatile organic compounds (VOCs) have great harm to the ecological environment and human health. At present, end treatment technologies such as catalytic oxidation, photocatalysis and biodegradation are still irreplaceable. The catalytic oxidation technology has been applied to VOCs emission reduction for more than 60 years, and is an effective technology. However, various VOCs put forward high requirements for treatment technologies and catalytic materials, and the catalytic oxidation technology still needs to be further developed. Moreover, from the perspective of energy saving and low carbon, efficient removal of low-concentration VOCs emitted by small and medium-sized pollution sources is still a serious problem.

[0003] Microwave energy (electromagnetic energy) can provide fast, selective and efficient volume heating for materials, and is considered as an excellent alternative heat source for promoting chemical reaction processes and improving reaction temperature. Microwave catalytic reaction has remarkable improvement compared with traditional thermal catalysis, including shorter reaction time, higher energy efficiency and higher product yield. At the same time, the average temperature of the catalyst under microwave reaction is significantly lower than that under traditional thermal catalysis at the same VOCs removal rate, which avoids high-temperature sintering of the catalyst and effectively improves the service life of the catalyst. At the same time, the microwave heating has small inertia and fast temperature control speed, which is conducive to automation and continuous production.

[0004] Metal-organic frameworks (MOFs) are composed of metal nodes and organic linkers, and have attracted wide attention due to their high specific surface area, adjustable porosity, diverse structure and adjustable functional sites. For catalytic oxidation reaction, the stability of MOF materials is limited in high temperature and oxygen environment. MOFs have been applied to sensing, catalysis, gas separation, energy storage, microwave absorption and other fields as templates or precursors to prepare porous carbon materials and composites of metals or metal oxides. The porous metal oxides derived from MOFs have highly porous structure and high surface area, which is beneficial to the adsorption and oxidation reaction of VOCs. However, there are few studies on the dual regulation of microwave absorption characteristics and catalytic performance by regulating metal ions. At the same time, by utilizing the characteristics of large specific surface area, high microwave absorption and catalytic performance of the material, a normal temperature adsorption-fast microwave catalytic oxidation system is designed to realize low-energy consumption removal of low-concentration VOCs emission sources, which has a wider application prospect. SUMMARY

[0005] The purpose of the application is to realize low-energy consumption removal of low-concentration VOCs emission sources.

[0006] To this end, the application provides a microwave response catalytic material, and the chemical composition of the microwave response catalytic material is Co a Mnb O x ; wherein the ratio of a to b is (2:1)-(1:2) and x is 2-4.

[0007] The application further provides a preparation method of the microwave response catalytic material, comprising the following steps:

[0008] (1) dissolving cobalt nitrate hexahydrate and manganese nitrate tetrahydrate in DMF to form solution A; dissolving terephthalic acid in DMF to form solution B;

[0009] (2) mixing solution B with solution A uniformly and then reacting, and then performing solid-liquid separation, washing and drying to obtain CoMn-MOF;

[0010] (3) calcining CoMn-MOF to obtain the microwave response catalytic material Co a Mn b O x .

[0011] Specifically, the molar ratio of cobalt nitrate hexahydrate and manganese nitrate tetrahydrate in the above step (1) is (2:1)-(1:2).

[0012] Specifically, the molar volume ratio of cobalt nitrate hexahydrate and manganese nitrate tetrahydrate to DMF in the above step (1) is (1-5) mmol:40 mL.

[0013] Specifically, the mass volume ratio of terephthalic acid to DMF in the above step (2) is (0.17-1.67) g:40 mL.

[0014] Specifically, the reaction temperature in the above step (2) is 80-120 DEG C, and the reaction time is 12-24 h.

[0015] Specifically, the calcination temperature in the above step (3) is 300-500 DEG C, and the holding time is 3-6 h.

[0016] The application further provides a VOCs adsorption-microwave catalytic oxidation system, comprising a microwave reactor; a catalytic material filling layer is arranged in the reaction tube of the microwave reactor; and the catalytic material is the microwave response catalytic material Co a Mn b O x .

[0017] The application further provides a VOCs treatment method based on the above VOCs normal temperature adsorption-microwave catalytic oxidation system, comprising the following steps: introducing VOCs into the reaction tube of the microwave reactor, and adsorbing VOCs by the catalytic material filling layer; starting the microwave reactor, heating the catalytic material by microwave, and oxidizing the adsorbed VOCs to generate carbon dioxide and water.

[0018] The application also provides application of the microwave-responsive catalytic material or the VOCs adsorption-microwave catalytic oxidation system or the VOCs treatment method in treating VOCs tail gas.

[0019] Compared with the prior art, the application has the following advantages and beneficial effects:

[0020] The microwave-responsive catalytic material provided by the application realizes dual regulation of microwave absorption characteristics and catalytic performance by regulating metal ions, and the MOF-derived porous metal oxide has a porous structure and a high surface area ratio, which is beneficial to adsorption and catalytic oxidation of VOCs and avoids the use of active carbon carriers for improving adsorption performance of traditional supported catalysts, and is beneficial to improving stability of the catalyst.

[0021] The VOCs adsorption-microwave catalytic oxidation system provided by the application is designed based on strong adsorption and rapid microwave heating characteristics of the metal organic framework-derived porous metal oxide, microwave catalysis has shorter reaction time and higher energy efficiency compared with traditional thermal catalysis, can realize adsorption of VOCs at room temperature and concentrated degradation in a short time, solves the high energy consumption problem of traditional thermal catalytic oxidation degradation of low-concentration VOCs of small pollution sources, and has good economic benefits and environmental protection significance.

[0022] The application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is an XRD pattern of Co a Mn b O x in the embodiment of the application.

[0024] Figure 2 is a microwave heating performance pattern of Co a Mn b O x in the embodiment of the application; wherein a is a result of change of temperature of the catalytic material with time of the catalytic material prepared in example 4 under different powers, and b is a result of change of temperature of different catalytic materials with power.

[0025] Figure 3 is a comparison pattern of catalytic performance of the VOCs adsorption-microwave catalytic oxidation system and conventional electric heating in the embodiment of the application; wherein a is a result of VOCs adsorption-microwave catalytic oxidation, and b is a result of conventional electric heating catalysis. DETAILED DESCRIPTION

[0026] The technical solutions in the present application will be clearly and completely described below with embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Although the representative embodiments of the present application have been described in detail, those skilled in the art will understand that various modifications and changes can be made to the present application without departing from the scope of the present application. Therefore, the scope of the present application should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0027] The present application provides a microwave-responsive catalytic material, the chemical composition of the microwave-responsive catalytic material is Co a Mn b O x ; wherein the ratio of a to b is (2:1)-(1:2), and x is 2-4. Co a Mn b O x The specific surface area of the material is greater than or equal to 200 g / m 2 , and the pore volume is greater than or equal to 0.1 mL / g.

[0028] The present application also provides a preparation method of a microwave-responsive catalytic material, comprising the following steps:

[0029] (1) dissolving cobalt nitrate hexahydrate and manganese nitrate tetrahydrate in DMF to form a solution A by ultrasonic dissolution; dissolving terephthalic acid in DMF to form a solution B by ultrasonic dissolution;

[0030] Preferably, the molar ratio of cobalt nitrate hexahydrate and manganese nitrate tetrahydrate is (2:1)-(1:2); and the molar volume ratio of the sum of cobalt nitrate hexahydrate and manganese nitrate tetrahydrate to DMF is (1-5) mmol:40 mL. Preferably, the mass-volume ratio of terephthalic acid to DMF is (0.17-1.67) g:40 mL;

[0031] (2) mixing solution B with solution A uniformly and then placing the mixture in a reaction kettle to react, preferably at a reaction temperature of 80-120 DEG C for 12-24 h, and then performing solid-liquid separation, washing and drying to obtain CoMn-MOF;

[0032] (3) calcining CoMn-MOF in a muffle furnace, preferably at a temperature of 300-500 DEG C for 3-6 h, and then naturally cooling to obtain a microwave-responsive catalytic material Co a Mn b O x .

[0033] The present application also provides a VOCs adsorption-microwave catalytic oxidation system, comprising a microwave reactor; a catalytic material filling layer is arranged in the reaction tube of the microwave reactor; and the catalytic material is the microwave-responsive catalytic material Coa Mn b O x .

[0034] The application also provides a VOCs treatment method based on the VOCs adsorption-microwave catalytic oxidation system at room temperature, which comprises the following steps: introducing VOCs into the reaction tube of the microwave reactor, adsorbing VOCs by the catalytic material filling layer for any time or after adsorption saturation, starting the microwave reactor, heating the catalytic material by microwave, rapidly heating the catalyst under the action of microwave, and oxidizing the adsorbed VOCs to generate carbon dioxide and water.

[0035] Specifically, 1g Co a Mn b O x The microwave power required for heating to 300 DEG C in the fixed-bed flow microwave reactor is less than or equal to 100 W, and the heating time is less than or equal to 30 minutes.

[0036] The microwave response catalytic material, the preparation method and the application effect thereof are studied through specific examples as follows.

[0037] Example 1: The example provides a microwave response catalytic material, which is prepared by the following steps:

[0038] (1) 1.5 mmol Co(NO3)2·6H2O and 1.5 mmol Mn(NO3)2·4H2O are added into 40 mL DMF to form a solution A, and 0.67 g of terephthalic acid is added into 40 mL DMF to form a solution B;

[0039] (2) After the solution B is added into the solution A and uniformly mixed, the mixture is placed in a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and is reacted at 80 DEG C for 24 hours; after solid-liquid separation, washing and drying, CoMn-MOF is obtained;

[0040] (3) The CoMn-MOF is calcined in a muffle furnace at 300 DEG C in air for 3 hours, and is naturally cooled to obtain a microwave response catalytic material Co1Mn1O x -300.

[0041] Example 2: The example provides a microwave response catalytic material, which is prepared by the following steps:

[0042] (1) 2 mmol Co(NO3)2·6H2O and 1 mmol Mn(NO3)2·4H2O are added into 40 mL DMF to form a solution A, and 0.67 g of terephthalic acid is added into 40 mL DMF to form a solution B;

[0043] (2) After solution B is added to solution A and mixed uniformly, it is placed in a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and reacted at 80°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF is obtained;

[0044] (3) CoMn-MOF is calcined in a muffle furnace at 300°C in air for 3 h, and naturally cooled to obtain microwave-responsive catalytic material Co2Mn1O x -300.

[0045] Example 3: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0046] (1) 1 mmol of Co(NO3)2·6H2O and 2 mmol of Mn(NO3)2·4H2O are added to 40 mL of DMF and ultrasonically mixed to form solution A, and 0.67 g of terephthalic acid is added to 40 mL of DMF and ultrasonically mixed to form solution B;

[0047] (2) After solution B is added to solution A and mixed uniformly, it is placed in a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and reacted at 80°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF is obtained;

[0048] (3) CoMn-MOF is calcined in a muffle furnace at 300°C in air for 3 h, and naturally cooled to obtain microwave-responsive catalytic material Co1Mn2O x -300.

[0049] Example 4: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0050] (1) 1.5 mmol of Co(NO3)2·6H2O and 1.5 mmol of Mn(NO3)2·4H2O are added to 40 mL of DMF and ultrasonically mixed to form solution A, and 0.67 g of terephthalic acid is added to 40 mL of DMF and ultrasonically mixed to form solution B;

[0051] (2) After solution B is added to solution A and mixed uniformly, it is placed in a 100 ml polytetrafluoroethylene-lined stainless steel autoclave, and reacted at 80°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF is obtained;

[0052] (3) CoMn-MOF is calcined in a muffle furnace at 400°C in air for 3 h, and naturally cooled to obtain microwave-responsive catalytic material Co1Mn1O x -400.

[0053] Example 5: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0054] (1) 2 mmol Co(N03)2-6H20 and 1 mmol Mn(N03)2-4H20 were added into 40 mL DMF and ultrasonically mixed to form solution A, 0.67 g terephthalic acid was added into 40 mL DMF and ultrasonically mixed to form solution B;

[0055] (2) After solution B was added into solution A and mixed uniformly, it was placed in a 100 ml polytetrafluoroethylene lined stainless steel autoclave, and reacted at 80°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF was obtained;

[0056] (3) CoMn-MOF was calcined in a muffle furnace at 400°C in air for 3 h, and naturally cooled to obtain microwave-responsive catalytic material Co2Mn1O x -400.

[0057] Example 6: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0058] (1) 1 mmol Co(N03)2-6H20 and 2 mmol Mn(N03)2-4H20 were added into 40 mL DMF and ultrasonically mixed to form solution A, 0.67 g terephthalic acid was added into 40 mL DMF and ultrasonically mixed to form solution B;

[0059] (2) After solution B was added into solution A and mixed uniformly, it was placed in a 100 ml polytetrafluoroethylene lined stainless steel autoclave, and reacted at 80°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF was obtained;

[0060] (3) CoMn-MOF was calcined in a muffle furnace at 400°C in air for 3 h, and naturally cooled to obtain microwave-responsive catalytic material Co1Mn2O x -400.

[0061] Example 7: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0062] (1) 1.5 mmol Co(N03)2-6H20 and 1.5 mmol Mn(N03)2-4H20 were added into 40 mL DMF and ultrasonically mixed to form solution A, 0.67 g terephthalic acid was added into 40 mL DMF and ultrasonically mixed to form solution B;

[0063] (2) After solution B was added into solution A and mixed uniformly, it was placed in a 100 ml polytetrafluoroethylene lined stainless steel autoclave, and reacted at 100°C for 24 h. After solid-liquid separation, washing and drying, CoMn-MOF was obtained;

[0064] (3) The CoMn-MOF is calcined in a muffle furnace at 400°C in air for 6h, and naturally cooled to obtain a microwave-responsive catalytic material Co1Mn1O x -400-1.

[0065] Example 8: This example provides a microwave-responsive catalytic material, which is prepared by the following steps:

[0066] (1) 1.5mmol Co(NO3)2·6H2O and 1.5mmol Mn(NO3)2·4H2O are added to 40mL DMF and ultrasonically mixed to form a solution A, and 0.67g terephthalic acid is added to 40mL DMF and ultrasonically mixed to form a solution B;

[0067] (2) The solution B is added to the solution A and mixed uniformly, and then placed in a 100ml polytetrafluoroethylene-lined stainless steel autoclave, and reacted at 120°C for 24h, and then subjected to solid-liquid separation, washing and drying to obtain CoMn-MOF;

[0068] (3) The CoMn-MOF is calcined in a muffle furnace at 400°C in air for 6h, and naturally cooled to obtain a microwave-responsive catalytic material Co1Mn1O x -400-2.

[0069] Example 9: This example tests the microwave-responsive catalytic material Co a Mn b O x performance.

[0070] 1. Catalyst characterization

[0071] The catalytic materials prepared in Examples 4-6 are subjected to X-ray diffraction, and the XRD characterization results are shown in Figure 1 Co a Mn b O x -300, the crystal structure is not obvious, Co a Mn b O x -400, the crystal structures of CoMn2O4 and MnCo2O4 are detected, indicating that the cobalt-manganese binary metal oxide catalyst is successfully prepared. Changing the ratio of metal atoms can prepare different crystal compounds.

[0072] 2. Microwave heating performance of the catalyst

[0073] The heating behavior of Co a Mn b O x under different microwave powers is determined, and the results are shown in Figure 2As shown, the catalyst temperature increases over time and reaches a steady state within 30 minutes. The steady state temperature increases with the increase of microwave power, and the reaction temperature of the catalyst can be adjusted by changing the microwave power.

[0074] 3. Catalytic performance

[0075] The catalytic materials Co a Mn b O x The catalytic performance of benzene under conventional electric heating and microwave was tested, and the results are shown in Table 1.

[0076] Table 1 Co a Mn b O x The catalytic performance of benzene under conventional electric heating and microwave

[0077]

[0078] The microwave-responsive catalytic material provided by the present application has higher energy efficiency under microwave catalysis than conventional thermal catalysis.

[0079] Example 10: The present example provides a VOCs adsorption-microwave catalytic oxidation system, comprising a microwave reactor; the quartz reaction tube of the microwave reactor is filled with a catalytic material to form a catalytic material filling layer; the catalytic material is the microwave-responsive catalytic material Co a Mn b O x -400.

[0080] At room temperature, benzene with a concentration of 100 ppm and a flow rate of 100 mL / min was introduced into the quartz reaction tube of the microwave reactor, so that the benzene was pre-adsorbed on Co a Mn b O x -400, after 60 minutes, the microwave reactor was started, and the catalyst was catalyzed under microwave irradiation (30W) for 20 minutes, and the concentration of the reactant (benzene) and the product (CO2) changed with time as shown in Figure 3 a. Benzene with the same concentration and flow rate was reacted under conventional electric heating (200℃) for 30 minutes, and the concentration of benzene and CO2 changed with time as shown in Figure 3 b. Since no other carbon-containing by-products are generated, the molar ratio of CO2 generation to benzene consumption is 6:1 according to reaction formula (1). The total amount of CO2 generated in this period can be calculated by Figure 3 the CO2 generation curve in the middle, and the total amount of CO2 generated in this period can be obtained by integrating the green area in the figure, wherein Figure 3 a. The amount of CO2 generated in 20 minutes in -5mol, Figure 3 The amount of CO2 produced in 30 minutes in b was 8.1*10 -5 mol, therefore, under this condition, the microwave catalytic intermittent reaction for 1 h can obtain similar effect as the continuous electric heating catalytic reaction for 75 minutes.

[0081]

[0082] The above examples are only illustrative of the present application, and do not constitute a limitation on the scope of protection of the present application, any design identical or similar to the present application shall fall within the scope of protection of the present application.

Claims

1. A microwave responsive catalytic material characterized by: The chemical composition of the microwave-responsive catalytic material is Co a Mn b O x ; wherein the ratio of a to b is (2:1) - (1:2) and x is 2-4.

2. A method of preparing a microwave responsive catalytic material, characterized by, The method comprises the following steps: (1) dissolving cobalt nitrate hexahydrate and manganese nitrate tetrahydrate in DMF to form solution A; dissolving terephthalic acid in DMF to form solution B; (2) mixing solution B with solution A, and then reacting, and then performing solid-liquid separation, washing, and drying to obtain CoMn-MOF; (3) calcining CoMn-MOF to obtain microwave-responsive catalytic material Co a Mn b O x .

3. The method for preparing the microwave-responsive catalytic material as described in claim 2, characterized in that: In step (1), the molar ratio of cobalt nitrate hexahydrate to manganese nitrate tetrahydrate is (2:1)-(1:2).

4. The method for preparing the microwave-responsive catalytic material as described in claim 3, characterized in that: In step (1), the molar volume ratio of cobalt nitrate hexahydrate to manganese nitrate tetrahydrate to DMF is (1-5) mmol:40 mL.

5. The method for preparing the microwave-responsive catalytic material as described in claim 2, characterized in that: In step (2), the mass-volume ratio of terephthalic acid to DMF is (0.17-1.67) g:40 mL.

6. The method for preparing the microwave-responsive catalytic material as described in claim 2, characterized in that: In step (2), the reaction temperature is 80-120°C, and the reaction time is 12-24 h.

7. The method for preparing the microwave-responsive catalytic material as described in claim 2, characterized in that: In step (3), the calcination temperature is 300-500°C, and the holding time is 3-6 h.

8. A VOCs adsorption-microwave catalytic oxidation system, characterized in that: The microwave reactor comprises a microwave reactor; a catalytic material filling layer is arranged in the reaction tube of the microwave reactor; the catalytic material is the microwave responsive catalytic material Co a Mn b O x .

9. A method of VOCs treatment, characterized by, The VOCs normal-temperature adsorption-microwave catalytic oxidation system based on claim 8 comprises the following steps: introducing VOCs into the reaction tube of the microwave reactor, and absorbing the VOCs by the catalytic material filling layer; starting the microwave reactor, heating the catalytic material by microwave, and oxidizing the absorbed VOCs to generate carbon dioxide and water.

10. The application of the microwave-responsive catalytic material according to claim 1 or the VOCs adsorption-microwave catalytic oxidation system according to claim 8 or the VOCs treatment method according to claim 9 in treating VOCs tail gas.

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