Cooperative treatment system for VOCs (volatile organic compounds) waste gas

Abstract

The invention discloses a VOCs waste gas co-processing system which comprises a combustion chamber, the lower end of the combustion chamber is connected with a plurality of evenly-distributed purification pipes, the purification pipes are connected with a VOCs waste gas conveying pipe, a purging air return pipe and a purified flue gas conveying pipe, and a fan is arranged on the VOCs waste gas conveying pipe; the purification pipe is filled with a heat storage ceramic body assembly, and the heat storage ceramic body assembly comprises a monatomic Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment; the upper layer temperature of the purification pipe is 500-900 DEG C, the middle layer temperature is 200-500 DEG C, and the lower layer temperature is 50-200 DEG C. The VOCs waste gas co-processing system has the advantages of being simple in process, easy and convenient to operate, low in energy consumption and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a VOCs waste gas coordinated treatment system. Background Art

[0002] Volatile organic pollutants (VOCs) are widely produced in the petroleum, chemical, plastic, rubber, pharmaceutical, printing, furniture, textile printing and dyeing, coating, paint, semiconductor manufacturing, synthetic materials, new energy and other industries. They have multiple environmental effects and are important precursors to the formation of ozone (O3) and fine particulate matter (PM2.5) pollution, causing great harm to the environment and human health. At present, the effective means of VOCs control is regenerative thermal oxidation technology (RTO), which has the characteristics of high purification efficiency, wide applicability, low operating costs, high degree of automation, simple operation, safe and reliable operation, etc. At the same time, it can treat organic substances including benzene, phenols, aldehydes, ketones, ethers, esters, alcohols, hydrocarbons, etc.

[0003] At the same time, the "Pharmaceutical Industry Air Pollutant Emission Standards (GB37823-2019), "Coating, Ink and Adhesive Industry Air Pollutant Emission Standards" (GB37824-2019), "Volatile Organic Compound Unorganized Emission Control Standards" (GB37822-2019), and "Technical Specifications for Industrial Organic Waste Gas Treatment Engineering by Regenerative Combustion Method" (HJ1093-2020), etc., which were implemented in 2019 and later, have formally raised the issue of nitrogen oxides produced after high-temperature combustion and the control of dioxins produced by chlorine-containing sources.

[0004] The application of catalytic thermal storage oxidation technology has led to the coordinated treatment of various pollutants produced at the end, especially the NO X In the treatment of CO and dioxins, the current treatment technology for these pollutants is single and inefficient, and cannot meet the current environmental protection ultra-clean emissions. Importantly, the treatment of dioxins often adopts the method of rapid cooling and activated carbon adsorption. This treatment method is only a physical avoidance and cannot be catalytically removed from a chemical perspective. It also has high operating energy consumption. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a VOCs waste gas collaborative treatment system, which realizes the efficient collaborative removal of multiple pollutants in VOCs waste gas and has the advantages of simple process, easy operation and low energy consumption.

[0006] The VOCs waste gas collaborative treatment system proposed in the present invention comprises a combustion chamber, the lower end of which is connected to a plurality of evenly distributed purification pipes, the purification pipes are connected to a VOCs waste gas delivery pipe, a purge return air pipe and a clean flue gas delivery pipe, and a fan is arranged on the VOCs waste gas delivery pipe; The purification tube is filled with a thermal storage ceramic assembly, which includes a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment; The temperature of the upper layer of the purification tube is 500-900°C, the temperature of the middle layer is 200-500°C, and the temperature of the lower layer is 50-200°C.

[0007] Preferably, the thermal storage ceramic assembly includes a first thermal storage ceramic body and a second thermal storage ceramic body arranged in sequence from above, the surface of the second thermal storage ceramic body is coated with a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment, the first thermal storage ceramic body fills the upper layer of the purification pipe, and the second thermal storage ceramic body fills the middle and lower layers of the purification pipe.

[0008] Preferably, the first heat storage ceramic body and the second heat storage ceramic body are honeycomb structures, have a specific heat capacity greater than 1000 J / (kg·K), a thermal efficiency of 90%-96%, and can achieve flue gas cooling.

[0009] Preferably, the method steps for preparing the single-atom Fe / CeO2 / ZrO2 catalyst are as follows: S1: mixing a cerium source and a zirconium source and dissolving the mixture in a mixture of ethanol and water to obtain a solution A; S2: mixing glycerol and citric acid and dissolving them in a mixture of ethanol and water to obtain solution B; S3: Solution A of S1 and solution B of S2 are mixed to form a transparent sol, and nano-scale CeO2 / ZrO2 powder is obtained by drying, calcining and ball milling; S4: mixing the iron source and the nano-scale CeO2 / ZrO2 powder of S3 and dissolving them in a mixture of ethanol and water to obtain solution C; S5: Urea is added to the solution C of S4, and the single-atom Fe / CeO2 / ZrO2 catalyst is prepared by stirring, filtering, drying and high-temperature pyrolysis.

[0010] Preferably, the cerium source is cerium nitrate and / or cerium carbonate; the zirconium source is zirconium nitrate and / or zirconium carbonate; and the iron source is one or more of ferric nitrate, ferric chloride and organic iron.

[0011] Preferably, the mass ratio of the cerium source, the zirconium source, the glycerol and the citric acid is 1:1-3:0.1-0.3:0.1-0.3.

[0012] Preferably, the mass ratio of nano-scale CeO2 / ZrO2 powder, iron source and urea is 1:5-10:0.5-1.5.

[0013] Preferably, the drying temperature in S3 is 50-150° C., and the drying time is 8-10 h; the calcination temperature is 350-550° C., and the time is 4-6 h.

[0014] Preferably, the drying temperature in S5 is 40-120° C., and the drying time is 10-12 hours.

[0015] Preferably, the high temperature pyrolysis temperature in S5 is 500-600° C. and the time is 12-24 h.

[0016] Beneficial technical effects of the present invention: The present invention combines the actual operation of RTO and adopts catalytic heat storage body to quickly cool down. Compared with the traditional rapid cooling and activated carbon spraying process, it achieves the purpose of energy saving and consumption reduction and treats dioxins from the source.

[0017] The present invention cleverly designs the spatial arrangement of the heat storage body, and efficiently treats pollutants in layers. Heat is stored in the upper layer of the RTO reaction chamber, and dioxin is catalyzed and NOx is reduced in the middle and lower layers. It has high treatment efficiency and can effectively solve the synthesis of terminal dioxins outside the tower, reduce the impact of dioxins on the heat storage capacity of the heat storage body, and reduce the leakage of dioxins.

[0018] The present invention targets the high temperature zone (250-500°C) in the middle layer of the RTO chamber where dioxins are easily synthesized. The selected single atom catalyst can provide abundant catalytic active sites to catalyze dioxins and solve the sintering and agglomeration of active components caused by high temperature in conventional catalysts.

[0019] The single-atom catalyst designed by the present invention is a metal uniformly loaded on a metal oxide carrier in the form of a single atom, and a catalytic reaction is carried out with the single atom as the catalytic active center. The obtained catalyst has a stable crystal form, high dispersion, and a strong ability to treat pollutants per unit area. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of the VOCs waste gas collaborative treatment system proposed in the present invention.

[0021] In the figure: 1-combustion chamber, 2-purification pipe, 3-first heat storage ceramic body, 4-second heat storage ceramic body, 5-VOCs waste gas conveying pipe, 6-purge return air pipe, 7-fan, 8-clean flue gas conveying pipe. DETAILED DESCRIPTION

[0022] The present invention will be further explained below in conjunction with specific embodiments.

[0023] Example 1 The VOCs waste gas collaborative treatment system proposed by the present invention comprises a combustion chamber 1, a plurality of evenly distributed purification pipes 2 are connected to the lower end of the combustion chamber 1, the purification pipe 2 is connected to a VOCs waste gas delivery pipe 5, a purge return air pipe 6 and a clean flue gas delivery pipe 8, and a fan 7 is arranged on the VOCs waste gas delivery pipe 5; The purification tube 2 is filled with a thermal storage ceramic assembly, which includes a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment; The temperature of the upper layer of the purification tube is 500-900℃, the temperature of the middle layer is 200-500℃, and the temperature of the lower layer is 50-200℃.

[0024] The heat storage ceramic body assembly includes a first heat storage ceramic body 3 and a second heat storage ceramic body 4 which are arranged in sequence from above. The surface of the second heat storage ceramic body 4 is coated with a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment. The first heat storage ceramic body 3 fills the upper layer of the purification pipe 2, and the second heat storage ceramic body 4 fills the middle and lower layers of the purification pipe 2.

[0025] The first heat storage ceramic body 3 and the second heat storage ceramic body 4 are honeycomb structures, with a specific heat capacity greater than 1000 J / (kg·K), a thermal efficiency of 90%-96%, and can achieve flue gas cooling.

[0026] The steps of the method for preparing the single-atom Fe / CeO2 / ZrO2 catalyst are as follows: S1: mixing a cerium source and a zirconium source and dissolving the mixture in a mixture of ethanol and water to obtain a solution A; S2: mixing glycerol and citric acid and dissolving them in a mixture of ethanol and water to obtain solution B; S3: Solution A of S1 and solution B of S2 are mixed to form a transparent sol, and nanometer CeO2 / ZrO2 powder is obtained by drying, calcining and ball milling; S4: mixing the iron source and the nano-scale CeO2 / ZrO2 powder of S3 and dissolving them in a mixture of ethanol and water to obtain solution C; S5: Urea is added to the solution C of S4, and the single-atom Fe / CeO2 / ZrO2 catalyst is prepared by stirring, filtering, drying and high-temperature pyrolysis.

[0027] The cerium source is cerium nitrate and / or cerium carbonate; the zirconium source is zirconium nitrate and / or zirconium carbonate; and the iron source is one or more of ferric nitrate, ferric chloride and organic iron.

[0028] The mass ratio of the cerium source, the zirconium source, glycerol and citric acid is 1:2:0.2:0.2.

[0029] The mass ratio of nano-scale CeO2 / ZrO2 powder, iron source and urea is 1:8:1.

[0030] The drying temperature in S3 is 100°C and the drying time is 10 hours; the calcination temperature is 450°C and the time is 5 hours.

[0031] The drying temperature in S5 is 80°C and the drying time is 12h; the high temperature pyrolysis temperature is 550°C and the time is 18h.

[0032] Example 2 The steps of the method for preparing the single-atom Fe / CeO2 / ZrO2 catalyst of this embodiment are as follows: S1: mixing a cerium source and a zirconium source and dissolving the mixture in a mixture of ethanol and water to obtain a solution A; S2: mixing glycerol and citric acid and dissolving them in a mixture of ethanol and water to obtain solution B; S3: Solution A of S1 and solution B of S2 are mixed to form a transparent sol, and nanometer CeO2 / ZrO2 powder is obtained by drying, calcining and ball milling; S4: mixing the iron source and the nano-scale CeO2 / ZrO2 powder of S3 and dissolving them in a mixture of ethanol and water to obtain solution C; S5: Urea is added to the solution C of S4, and the single-atom Fe / CeO2 / ZrO2 catalyst is prepared by stirring, filtering, drying and high-temperature pyrolysis.

[0033] The cerium source is cerium carbonate; the zirconium source is zirconium carbonate; and the iron source is ferric chloride.

[0034] The mass ratio of the cerium source, the zirconium source, glycerol and citric acid is 1:1:0.1:0.1.

[0035] The mass ratio of nano-scale CeO2 / ZrO2 powder, iron source and urea is 1:5:0.5.

[0036] The drying temperature in S3 is 150°C and the drying time is 10 hours; the calcination temperature is 550°C and the time is 6 hours.

[0037] The drying temperature in S5 is 120°C and the drying time is 12h; the high temperature pyrolysis temperature is 600°C and the time is 24h.

[0038] Example 3 The steps of the method for preparing the single-atom Fe / CeO2 / ZrO2 catalyst of this embodiment are as follows: S1: mixing a cerium source and a zirconium source and dissolving the mixture in a mixture of ethanol and water to obtain a solution A; S2: mixing glycerol and citric acid and dissolving them in a mixture of ethanol and water to obtain solution B; S3: Solution A of S1 and solution B of S2 are mixed to form a transparent sol, and nanometer CeO2 / ZrO2 powder is obtained by drying, calcining and ball milling; S4: mixing the iron source and the nano-scale CeO2 / ZrO2 powder of S3 and dissolving them in a mixture of ethanol and water to obtain solution C; S5: Urea is added to the solution C of S4, and the single-atom Fe / CeO2 / ZrO2 catalyst is prepared by stirring, filtering, drying and high-temperature pyrolysis.

[0039] The cerium source is cerium nitrate; the zirconium source is zirconium nitrate; and the iron source is iron nitrate.

[0040] The mass ratio of the cerium source, the zirconium source, glycerol and citric acid is 1:3:0.3:0.3.

[0041] The mass ratio of nano-scale CeO2 / ZrO2 powder, iron source and urea is 1:10:1.5.

[0042] The drying temperature in S3 is 50°C and the drying time is 8h; the calcination temperature is 350°C and the time is 4h.

[0043] The drying temperature in S5 is 40°C and the drying time is 10 hours; the high temperature pyrolysis temperature is 600°C and the time is 12 hours.

[0044] The activity of the catalyst prepared in Examples 1-3 was tested under the following conditions: 50 ppm NO X , 1000ppmCO, 1ngTEQ / m 3 Chlorobenzene, 10% O2, 95.5% N2, space velocity 100000h - The test temperatures are 50℃, 150℃, 250℃, 350℃ and 450℃ respectively. The test results are shown in Table 1.

[0045] Table 1 Catalytic performance test results of catalysts

[0046] It can be seen from the test results in Table 1 that the single-atom catalyst of the present invention has a very high removal rate for dioxins under the condition of 250-500°C in the middle temperature zone of the regenerator, and has a good oxidation performance for CO. At the same time, under the condition of 50-200°C in the lower temperature zone of the regenerator, it has a very high removal rate for NO. XIt also has a very strong reduction efficiency; it can be seen from the test results of Examples 1-3 that the active component single-atom iron of the present invention has a synergistic effect on improving the performance of the catalyst in removing dioxins, carbon monoxide and reducing nitrogen oxides due to its high dispersion performance on the catalyst carrier; it can also be seen from the test results of Examples 1-3 that the prepared zirconium-cerium composite carrier can better solve the situation of carrier crystal mutation and active component agglomeration at high temperature, and the addition of cerium oxide forms a very strong structure-activity effect between "metal-carrier", and also introduces more active sites for single-atom iron on the carrier. The present invention can better achieve the effect of removing dioxins at the source, while reducing carbon and slowing down the coverage restriction of carbon accumulation on the catalyst, and fully achieves the purpose of zoning and coordinated treatment of multiple pollutants.

Claims

1. VOCs waste gas collaborative treatment system, characterized in that: It comprises a combustion chamber (1), the lower end of the combustion chamber (1) is connected to a plurality of evenly distributed purification pipes (2), the purification pipe (2) is connected to a VOCs waste gas delivery pipe (5), a purge return air pipe (6) and a clean flue gas delivery pipe (8), and the VOCs waste gas delivery pipe (5) is provided with a fan (7); The purification tube (2) is filled with a heat storage ceramic component, which includes a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment; The temperature of the upper layer of the purification tube (2) is 500-900°C, the temperature of the middle layer is 200-500°C, and the temperature of the lower layer is 50-200°C.

2. The VOCs waste gas collaborative treatment system according to claim 1 is characterized in that: The heat storage ceramic assembly comprises a first heat storage ceramic (3) and a second heat storage ceramic (4) which are arranged in sequence from top to bottom; the surface of the second heat storage ceramic (4) is coated with a single-atom Fe / CeO2 / ZrO2 catalyst for VOCs waste gas treatment; the first heat storage ceramic (3) fills the upper layer of the purification pipe (2); and the second heat storage ceramic (4) fills the middle layer and the lower layer of the purification pipe (2).

3. The VOCs waste gas collaborative treatment system according to claim 2 is characterized in that: The first heat storage ceramic body (3) and the second heat storage ceramic body (4) are honeycomb structures, have a specific heat capacity greater than 1000 J / (kg·K), a thermal efficiency of 90%-96%, and are capable of cooling the flue gas.

4. The VOCs waste gas collaborative treatment system according to claim 2, characterized in that: The method steps for preparing the single-atom Fe / CeO2 / ZrO2 catalyst are as follows: S1: mixing a cerium source and a zirconium source and dissolving the mixture in a mixture of ethanol and water to obtain a solution A; S2: mixing glycerol and citric acid and dissolving them in a mixture of ethanol and water to obtain solution B; S3: Solution A of S1 and solution B of S2 are mixed to form a transparent sol, and nanometer CeO2 / ZrO2 powder is obtained by drying, calcining and ball milling; S4: mixing the iron source and the nano-scale CeO2 / ZrO2 powder of S3 and dissolving them in a mixture of ethanol and water to obtain solution C; S5: Urea is added to the solution C of S4, and the single-atom Fe / CeO2 / ZrO2 catalyst is prepared by stirring, filtering, drying and high-temperature pyrolysis.

5. The VOCs waste gas collaborative treatment system according to claim 4, characterized in that: The cerium source is cerium nitrate and / or cerium carbonate; the zirconium source is zirconium nitrate and / or zirconium carbonate; the iron source is one or more of ferric nitrate, ferric chloride and organic iron.

6. The VOCs waste gas collaborative treatment system according to claim 4, characterized in that: The mass ratio of the cerium source, the zirconium source, the glycerol and the citric acid is 1:1-3:0.1-0.3:0.1-0.

3.

7. The VOCs waste gas coordinated treatment system according to claim 4 is characterized in that: The mass ratio of nano-scale CeO2 / ZrO2 powder, iron source and urea is 1:5-10:0.5-1.

5.

8. The VOCs waste gas coordinated treatment system according to claim 4, characterized in that: The drying temperature in S3 is 50-150°C, and the drying time is 8-10 hours; the calcination temperature is 350-550°C, and the time is 4-6 hours.

9. The VOCs waste gas coordinated treatment system according to claim 4, characterized in that: The drying temperature in S5 is 40-120° C., and the drying time is 10-12 hours.

10. The VOCs waste gas coordinated treatment system according to claim 4, characterized in that: The high temperature pyrolysis temperature of S5 is 500-600℃ and the time is 12-24h.

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