Method for treating oxygen-containing tail gas from preparation of epichlorohydrin by hydrogen peroxide method

Abstract

The present application relates to the technical field of oxygen-containing tail gas treatment, and discloses a method for treating oxygen-containing tail gas generated in the preparation of epichlorohydrin by hydrogen peroxide method. The method comprises the following steps: condensing and separating the oxygen-containing tail gas generated in the preparation of epichlorohydrin by hydrogen peroxide method, diluting the gaseous phase obtained after condensation and separation with explosion suppression gas, washing the obtained mixed gaseous phase, and then performing deoxidation treatment on the washed mixed gaseous phase in the presence of a catalyst and a reducing gas; wherein the catalyst contains a carrier, an active component supported on the carrier, and an additive, the active component is at least one of oxides of Pd, Pt, Ru and Rh, and the additive is at least one of oxides of Zn, Na, K, Mg and Cu. The method can efficiently remove oxygen at a low temperature by catalytic deoxidation, thereby reducing the amount of VOCs to be treated and achieving safety and environmental protection.

Description

Technical Field

[0001] This invention relates to oxygen-containing exhaust gas treatment technology, specifically to a method for treating oxygen-containing exhaust gas from the hydrogen peroxide method for preparing epichlorohydrin. Background Technology

[0002] The hydrogen peroxide method for producing epichlorohydrin (HPECH) boasts advantages such as high atom utilization and environmental friendliness, making it the most promising ECH production technology for industrialization. Currently, the industrial pilot plant is under construction. However, during this process, hydrogen peroxide undergoes byproduct decomposition to generate oxygen. This oxygen can easily form a flammable and explosive mixture during gas-liquid separation, posing a significant risk of combustion and explosion. Currently, continuous nitrogen supplementation is used to dilute the oxygen and prevent combustion and explosion. This not only consumes large amounts of nitrogen, increasing production costs, but also increases VOC treatment requirements, thus increasing environmental pressure.

[0003] Patent application CN107899402B discloses a method for treating tail gas from a chlorohydrin-based propylene oxide plant. The organic waste gas generated during the chlorohydrin process of the propylene oxide plant is treated by removing acidic gases in an alkaline scrubbing tower. It is then introduced into a safety water seal tank, which has an air inlet. The chlorohydrin-based organic waste gas and supplementary air are mixed and then fed into a blower. The gas in the blower outlet pipeline is tested for combustible gas content by an online VOC gas detector, and then metered by a remote flow meter before being transported to the safety water seal tank of the caustic soda flake plant. Finally, it enters the molten salt furnace as combustion air for incineration. This method wastes resources and increases the operational risk of the incinerator.

[0004] Patent application CN105642082B discloses a tail gas treatment device and process for producing propylene oxide from propylene epoxidation using hydrogen peroxide. The device includes a tail gas emission device, a deoxygenation reactor, and a propane separation tower connected in series. The top of the propane separation tower is connected to the bottom of the propylene absorption tower. The tail gas, composed of propylene, propylene oxide, methanol, propane, and oxygen, discharged from the tail gas emission device of the epoxidation reactor, reacts in the deoxygenation reactor. The tail gas discharged from the deoxygenation reactor enters the propane separation tower for separation. The distillate from the top of the propane separation tower enters the propylene absorption tower from the bottom, and after being fully absorbed by the absorbent entering from the top of the propylene absorption tower, it is discharged from the propylene absorption tower. The material at the bottom of the propane separation tower enters the subsequent purification section to purify the propylene oxide. The separated material in the middle of the propane separation tower enters the propane collector. This tail gas treatment process is applicable to propylene systems, but its applicability to systems containing chlorinated propylene requires further evaluation.

[0005] In recent years, catalytic deoxygenation has become an effective deoxygenation method, attracting widespread research and significant industrial applications due to its substantial advantages in economics, environmental protection, and energy conservation. This study focuses on the oxygen-containing tail gas generated during the hydrogen peroxide method for producing epichlorohydrin (HPECH). A catalytic oxidation deoxygenation treatment method and system have been developed to effectively eliminate safety hazards, reduce nitrogen consumption, and improve energy efficiency during the production process. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of existing technologies in the treatment of oxygen-containing tail gas generated during the hydrogen peroxide method for preparing epichlorohydrin, which easily leads to the formation of flammable and explosive oxygen-containing tail gas, consumes a large amount of nitrogen, and increases the VOC treatment volume. This invention provides a method for treating oxygen-containing tail gas generated during the hydrogen peroxide method for preparing epichlorohydrin. This method utilizes catalytic oxidation deoxygenation to effectively reduce the oxygen content in the oxygen-containing tail gas generated during the hydrogen peroxide method for preparing epichlorohydrin, eliminates safety hazards, and reduces the consumption of suppression gas and the VOC treatment volume.

[0007] To achieve the above objectives, the present invention provides a method for treating oxygen-containing tail gas generated during the preparation of epichlorohydrin by the hydrogen peroxide method. The method includes: condensing and separating the oxygen-containing tail gas generated during the preparation of epichlorohydrin by the hydrogen peroxide method; diluting the gas phase obtained after condensation and separation with an explosion-suppressing gas; washing the resulting mixed gas phase; and then deoxygenating the washed mixed gas phase in the presence of a catalyst and a reducing gas.

[0008] The catalyst contains a support and an active component and an auxiliary agent supported on the support. The active component is at least one of the oxides of Pd, Pt, Ru, and Rh, and the auxiliary agent is at least one of the oxides of Zn, Na, K, Mg, and Cu.

[0009] Preferably, in the oxygen-containing tail gas generated during the preparation of epichlorohydrin by the hydrogen peroxide method, the oxygen content is 85-98% by volume, the allyl chloride content is 1-10% by volume, and the epichlorohydrin content is 0.1-1% by volume.

[0010] Preferably, the explosion-suppressing gas is selected from at least one of nitrogen, helium, argon and methane.

[0011] Preferably, in the diluted mixed gas phase, the volume ratio of oxygen to the explosion-suppressing gas is 1:20-90.

[0012] Preferably, the detergent used in the washing process is at least one of ethanol, ethylene glycol, methanol, and deionized water.

[0013] Preferably, the volume ratio of the detergent to the mixed gas phase is 1:5-30.

[0014] Preferably, the weight ratio of the active component, the auxiliary agent, and the carrier is 0.01-1:1-20:100.

[0015] Preferably, the carrier is selected from at least one of alumina, ceramics, zeolite molecular sieves, silicon dioxide, and activated carbon.

[0016] Preferably, the deoxygenation treatment conditions include: a temperature of 120-300℃, a pressure of 0.1-1 MPa, and a reaction space velocity of 1500-4500 h⁻¹. -1 .

[0017] Preferably, the reducing gas is selected from at least one of hydrogen, carbon monoxide, propane, and chloropropane.

[0018] Preferably, the molar ratio of oxygen to the reducing gas in the washed mixed gas phase is 1:2-10.

[0019] Preferably, the method is implemented in an exhaust gas treatment system, which includes a first condensation separation device, a scrubbing device, and a deoxygenation treatment device connected in sequence, wherein...

[0020] The first condensation separation device is equipped with a first gas release device. After the oxygen-containing tail gas enters the first condensation separation device, it undergoes condensation separation. The explosion-suppressing gas delivered by the first gas release device dilutes the gas phase obtained after condensation separation to obtain a mixed gas phase.

[0021] The washing device is equipped with a liquid release device, and the washing agent provided by the liquid release device is used to wash the mixed gas phase from the first condensation separation device to obtain the washed mixed gas phase.

[0022] The deoxidation treatment device is equipped with a second gas release device and a heating device for heating the materials in the deoxidation treatment device. The mixed gas phase after washing from the washing device is mixed and reacted with the reducing gas entering through the second gas release device.

[0023] Preferably, the exhaust gas treatment system further includes a second condensation separation device and a circulation device, wherein the reaction products from the deoxygenation treatment device are condensed and separated in the second condensation separation device, and the separated gas phase is returned to the first condensation separation device for recycling through the circulation device.

[0024] The method for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin, as described in this invention, utilizes catalytic oxidation deoxygenation, enabling efficient recovery of allyl chloride from the oxygen-containing tail gas and efficient removal of oxygen at a relatively low catalytic temperature. Furthermore, the method described in this invention can essentially achieve complete recovery and recycling of the anti-explosion gases in the oxygen-containing tail gas, reducing production costs and the amount of VOCs in the oxygen-containing tail gas, making it safer and more environmentally friendly. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an exemplary system for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin.

[0026] Explanation of reference numerals in the attached figures

[0027] 1. First condensation and separation device; 11. First gas release device; 2. Washing device; 21. Liquid release device; 3. Deoxygenation treatment device; 31. Second gas release device; 4. Second condensation and separation device; 5. Circulation device. Detailed Implementation

[0028] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] The method for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin according to the present invention includes:

[0031] The oxygen-containing tail gas generated during the preparation of epichlorohydrin by hydrogen peroxide method is condensed and separated. The gas phase obtained after condensation and separation is diluted with an explosion-suppressing gas. The resulting mixed gas phase is then washed. Finally, in the presence of a catalyst and a reducing gas, the washed mixed gas phase is deoxygenated.

[0032] The catalyst contains a support and an active component and an auxiliary agent supported on the support. The active component is at least one of the oxides of Pd, Pt, Ru, and Rh, and the auxiliary agent is at least one of the oxides of Zn, Na, K, Mg, and Cu.

[0033] In this invention, the oxygen-containing tail gas generated during the preparation of epichlorohydrin by the hydrogen peroxide method contains 85-98% by volume of oxygen, 1-10% by volume of allyl chloride, and 0.1-1% by volume of epichlorohydrin.

[0034] In this invention, the explosion suppression gas is selected from at least one of nitrogen, helium, argon and methane.

[0035] In some embodiments, the volume ratio of oxygen to the explosion-suppressing gas in the diluted gas mixture is 1:30-80, preferably 1:30-60, and more preferably 1:40-50. In these embodiments, when the volume ratio of oxygen to the explosion-suppressing gas in the diluted gas mixture is within the above range (especially the preferred range), it is possible to prevent the VOCs in the diluted gas mixture from reaching the explosion limit, and at the same time, to avoid wasting materials in subsequent processing steps.

[0036] In this invention, the detergent used in the washing process is at least one of ethanol, ethylene glycol, methanol, and deionized water, preferably ethanol or methanol. In the method described in this invention, the detergent is used to remove residual allyl chloride from the oxygen-containing exhaust gas, preventing it from contaminating the catalyst and affecting subsequent treatment processes.

[0037] In some embodiments, the volume ratio of the detergent to the mixed gas phase is 1:5-30, preferably 1:5-20, and more preferably 1:5-10. In these embodiments, when the volume ratio of the detergent to the mixed gas phase is within the above range (especially the preferred range), it is possible to efficiently remove the allyl chloride from the oxygen-containing exhaust gas, avoiding its contamination of the catalyst and affecting subsequent treatment processes.

[0038] In some embodiments, the weight ratio of the active component, the auxiliary agent, and the support can be 0.01-1:1-20:100, preferably 0.01-0.5:1-15:100, and more preferably 0.1-0.5:1-10:100. In these embodiments, when the weight ratio of the active component, the auxiliary agent, and the support is within the above range (especially within the preferred range), the catalyst exhibits superior catalytic activity and chlorine resistance.

[0039] In a preferred embodiment, the additive may be an oxide of Cu and / or an oxide of Zn. In these preferred embodiments, when the additive is selected as described above, the catalyst exhibits better catalytic activity and chlorine resistance.

[0040] In some embodiments, the carrier may be at least one of alumina, ceramics, molecular sieves and zeolites, preferably alumina.

[0041] In the method described in this invention, the catalyst can be prepared according to conventional processes in the art. In a preferred embodiment, the preparation method of the catalyst includes:

[0042] The precious metal precursor and the auxiliary precursor are attached to the carrier, and then the resulting product is calcined.

[0043] The noble metal precursor is selected from one or more of Pd salt, Pt salt, Ru salt and Rh salt;

[0044] The precursor of the auxiliary agent can be one or more of Zn salt, Na salt, K salt, Mg salt and Cu salt.

[0045] In this invention, the Pd salt can be at least one of PdCl2, Pd(NO3)2, and tetraamminepalladium acetate, preferably PdCl2. The Pt salt can be at least one of PtCl2, dinitrosodiammineplatinum, and tetraammineplatinum acetate, preferably PtCl2. The Ru salt can be at least one of Ru(C2O4)2, RuCl3·3H2O, and Ru(NO3)3, preferably Ru(NO3)3. The Rh salt can be at least one of rhodium nitrate, rhodium phosphate, and RhCl3·3H2O, preferably RhCl3·3H2O.

[0046] In this invention, the Zn salt can be at least one of Zn(NO3)2, ZnSO4, and ZnCl2, preferably Zn(NO3)2. The Na salt can be at least one of NaNO3, Na2SO4, and NaCl, preferably NaNO3. The K salt can be at least one of KNO3, K2SO4, and KCl, preferably KNO3. The Mg salt can be at least one of Mg(NO3)2, MgSO4, and MgCl2, preferably Mg(NO3)2. The Cu salt can be at least one of CuCl2, CuSO4, and Cu(NO3)2, preferably Cu(NO3)2.

[0047] In a preferred embodiment, the weight ratio of the precious metal precursor, the auxiliary precursor and the carrier can be 0.01-1:1-20:100, more preferably 0.1-0.5:1-10:100.

[0048] In a preferred embodiment, the attachment method can be at least one of precipitation, impregnation, and spraying, with impregnation being more preferred. In these preferred embodiments, the prepared catalyst exhibits superior catalytic oxidation activity.

[0049] In a preferred embodiment, the process of attaching the precious metal precursor and the auxiliary precursor to the carrier may further include: preparing the precious metal precursor and the auxiliary precursor into an impregnation solution, impregnating the carrier in the impregnation solution, heating and stirring to evaporate to dryness, and then drying the resulting solid product.

[0050] More preferably, the drying conditions may include a temperature of 100-150°C and a time of 8-12 hours. In these preferred embodiments, the prepared catalyst exhibits superior catalytic oxidation activity.

[0051] In a preferred embodiment, the calcination conditions may include: a temperature of 400-800℃, more preferably 500-600℃, and a time of 1-8 h, more preferably 3-5 h. In these preferred embodiments, the prepared catalyst exhibits superior catalytic oxidation activity.

[0052] In the method described in this invention, the conditions for the deoxygenation treatment include: a temperature of 120-300℃, preferably 150-250℃, more preferably 200-250℃; a pressure of 0.1-1MPa, preferably 0.1-0.8MPa, more preferably 0.1-0.5MPa; and a reaction space velocity of 1500-4500 h⁻¹. -1 Preferably 2000-4000h -1 More preferably 2500-3500h -1 In the method described in this invention, when the conditions of the deoxidation treatment are within the above-mentioned range (especially within the preferred range), the deoxidation treatment is more efficient and the degree of deoxidation is deeper, which can effectively achieve the separation and recycling of the explosion suppression gas.

[0053] In this invention, the reducing gas can be at least one of hydrogen, carbon monoxide, propane and chloropropane, preferably hydrogen.

[0054] In some embodiments, the molar ratio of oxygen to the reducing gas in the washed mixed gas phase can be 1:2-10, preferably 1:2-6, and more preferably 1:3-5. In these embodiments, when the molar ratio of oxygen to the reducing gas is within the above range (especially the preferred range), the catalytic reaction process has higher deoxygenation efficiency and a deeper degree of deoxygenation, effectively achieving the separation and recycling of the explosion-suppressing gas.

[0055] The method for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin, as described in this invention, can be implemented using a combination of conventional process equipment in the art. In a preferred embodiment, the method is implemented in a tail gas treatment system. Figure 1This is a schematic diagram of an exemplary exhaust gas treatment system. The system includes a first condensation separation device 1, a washing device 2, and a deoxygenation treatment device 3 connected in sequence.

[0056] The first condensation separation device 1 is equipped with a first gas release device 11. After the oxygen-containing tail gas enters the first condensation separation device 1, it is condensed and separated. The explosion suppression gas delivered by the first gas release device 11 is used to dilute the gas phase obtained after condensation and separation to obtain a mixed gas phase.

[0057] The washing device 2 is equipped with a liquid release device 21, and the washing agent provided by the liquid release device 21 is used to wash the mixed gas phase from the first condensation separation device 1 to obtain the washed mixed gas phase.

[0058] The deoxidation treatment device 3 is equipped with a second gas release device 31 and a heating device for heating the material in the deoxidation treatment device 3. The mixed gas phase after washing from the washing device 2 is mixed and reacted with the reducing gas entering through the second gas release device 31.

[0059] In this exemplary embodiment, the exhaust gas treatment system further includes a second condensation separation device 4 and a circulation device 5. The reaction products from the deoxygenation treatment device 3 are condensed and separated in the second condensation separation device 4, and the separated gas phase is returned to the first condensation separation device 1 for recycling through the circulation device 5.

[0060] In this exemplary embodiment, the oxygen-containing tail gas generated from the preparation of epichlorohydrin by the hydrogen peroxide method enters the first condensation separation device 1 through the first gas phase inlet located in the middle of the first condensation separation device 1. The liquid chloropropene obtained after condensation separation is discharged from the bottom of the first condensation separation device 1 for recycling. The remaining oxygen-containing tail gas is diluted by the explosion-suppressing gas blown in by the first gas release device 11 located at the top of the first condensation separation device 1 and then enters the washing device 2 from the top.

[0061] In this exemplary embodiment, the mixed gas phase obtained by the first condensation separation device 1 enters the washing device 2 and flows from bottom to top. The detergent sprayed by the liquid release device 21 located at the top of the washing device 2 flows from top to bottom. After the mixed gas phase comes into full contact with the detergent, it is discharged from the top to the deoxygenation treatment device 3. The detergent is discharged from the bottom for recycling.

[0062] In this exemplary embodiment, the deoxygenation treatment device 3 is provided with a catalyst bed containing a catalyst. The reducing gas blown in by the second gas release device 31 located at the top of the deoxygenation treatment device 3 and the washed mixed gas phase entering the deoxygenation treatment device 3 undergo catalytic deoxygenation on the surface of the catalyst bed. The mixed gas phase obtained from the reaction is discharged from the bottom of the deoxygenation treatment device 3 to the second condensation separation device 4.

[0063] In this exemplary embodiment, the gaseous product from the second condensation separation device 4 enters the second condensation separation device 4 through the second gaseous inlet located in the middle of the second condensation separation device 4. The condensate obtained after condensation separation is discharged through the bottom of the second condensation separation device 4 for recycling. The explosion suppression gas obtained by separation is discharged through the top of the second condensation separation device 4 and enters the first condensation separation device 1 through the circulation device 5 as at least a portion of the explosion suppression gas for recycling.

[0064] The following examples further illustrate the method for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0065] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0066] The following examples are in Figure 1 The system shown is implemented in the process of treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin. The system includes a first condensation and separation device 1, a washing device 2, a deoxygenation treatment device 3, a second condensation and separation device 4, and a circulation device 5 connected in sequence.

[0067] The first condensation separation device 1 is equipped with a first gas release device 11. The oxygen-containing tail gas generated by the hydrogen peroxide method for preparing epichlorohydrin enters the first condensation separation device 1 through the first gas phase inlet located in the middle of the first condensation separation device 1. The liquid chloropropene obtained after condensation separation is discharged from the bottom of the first condensation separation device 1 for recycling. The remaining oxygen-containing tail gas is diluted by the explosion-suppressing gas blown in by the first gas release device 11 located at the top of the first condensation separation device 1 and then enters the washing device 2 from the top.

[0068] The mixed gas phase obtained from the first condensation separation device 1 enters the washing device 2 and flows from bottom to top. The detergent sprayed by the liquid release device 21 set at the top of the washing device 2 flows from top to bottom. After the mixed gas phase comes into full contact with the detergent, it is discharged from the top to the deoxygenation treatment device 3. The detergent is discharged from the bottom for recycling.

[0069] The deoxygenation treatment device 3 is provided with a catalyst bed containing a catalyst. The reducing gas blown in by the second gas release device 31 located at the top of the deoxygenation treatment device 3 and the washed mixed gas phase entering the deoxygenation treatment device 3 undergo catalytic deoxygenation on the surface of the catalyst bed. The mixed gas phase obtained from the reaction is discharged from the bottom of the deoxygenation treatment device 3 to the second condensation separation device 4.

[0070] The gaseous product from the second condensation separation device 4 enters the second condensation separation device 4 through the second gaseous inlet located in the middle of the second condensation separation device 4. The condensate obtained after condensation separation is discharged through the bottom of the second condensation separation device 4 for recycling. The explosion suppression gas obtained by separation is discharged through the top of the second condensation separation device 4 and enters the first condensation separation device 1 through the circulation device 5 as at least a part of the explosion suppression gas for recycling.

[0071] Preparation Example 1

[0072] (1) Dissolve Pd(NO3)2 and Zn(NO3)2 in deionized water to obtain a mixed solution of Pd(NO3)2 and Zn(NO3)2;

[0073] (2) Pd(NO3)2 and Zn(NO3)2 were impregnated onto the support Al2O3 by excess impregnation. The water was evaporated under heating and stirring. The resulting solid product was then dried at 120°C for 10 h and finally calcined at 550°C for 4 h to obtain the catalyst for the catalytic reaction described in this invention, designated as Cat-1. The weight ratio of Pd in ​​Pd(NO3)2 to Zn in Zn(NO3)2 and the weight ratio of the support was 0.3:5:100.

[0074] Preparation Example 2

[0075] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the auxiliary precursor is NaNO3, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-2, wherein the weight ratio of the amount of Pd in ​​Pd(NO3)2 to the amount of Na in NaNO3 to the amount of the support is 0.3:3:100.

[0076] Preparation Example 3

[0077] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the auxiliary precursor is Cu(NO3)2, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-3, wherein the weight ratio of the amount of Pd in ​​Pd(NO3)2 to the amount of Cu in Cu(NO3)2 and the amount of support is 0.3:10:100.

[0078] Preparation Example 4

[0079] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the auxiliary precursor is Mg(NO3)2, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-4, wherein the weight ratio of the amount of Pd in ​​Pd(NO3)2 to the amount of Mg in Mg(NO3)2 and the amount of the support is 0.3:10:100.

[0080] Preparation Example 5

[0081] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the noble metal precursor is PdCl2 and the auxiliary precursor is Mg(NO3)2, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-5, wherein the weight ratio of the amount of Pd in ​​PdCl2 and the amount of Mg in Mg(NO3)2 to the amount of the support is 0.3:10:100.

[0082] Preparation Example 6

[0083] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the noble metal precursor is PdCl2 and the auxiliary precursor is KNO3, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-6, wherein the weight ratio of the amount of Pd in ​​PdCl2 and the amount of K in KNO3 to the amount of the support is 0.3:5:100.

[0084] Preparation Example 7

[0085] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the noble metal precursor is tetraamminepalladium acetate, and the catalyst for the catalytic reaction of the present invention is prepared, named Cat-7, wherein the weight ratio of the amount of Pd in ​​tetraamminepalladium acetate and the amount of Zn in Zn(NO3)2 to the amount of support is 0.3:5:100.

[0086] Preparation Example 8

[0087] This embodiment is carried out according to the method of embodiment 1, except that in step (1), the noble metal precursor is tetraamminepalladium acetate, the auxiliary precursor is KNO3, and the catalyst for the catalytic reaction of the present invention is prepared as Cat-8. The weight ratio of the amount of Pd in ​​tetraamminepalladium acetate to the amount of K in the auxiliary precursor KNO3 and the amount of the support is 0.3:3:100.

[0088] Example 1

[0089] (1) The oxygen-containing tail gas generated from the preparation of epichlorohydrin by hydrogen peroxide method with an oxygen content of 90% by volume, an allyl chloride content of 9% by volume, and an epichlorohydrin content of 1% by volume enters the first condensation separation device 1 through the first gas phase inlet. The liquid allyl chloride obtained after condensation separation is discharged from the bottom of the first condensation separation device 1 for recycling. The remaining oxygen-containing tail gas is diluted by nitrogen gas blown in by the first gas release device 11 and then enters the washing device 2 from the top. In the diluted mixed gas phase, the oxygen content is 2% by volume and the nitrogen content is 98% by volume.

[0090] (2) After the mixed gas phase enters the washing device 2, it flows from bottom to top, while the detergent methanol sprayed by the liquid release device 21 flows from top to bottom. After the mixed gas phase and the detergent methanol come into full contact, they are discharged from the top to the deoxygenation treatment device 3. The methanol solution containing chloropropylene is discharged from the bottom for recycling. The flow ratio of the mixed gas phase to the detergent methanol is 1:5.

[0091] (3) The catalyst Cat-1 prepared in Preparation Example 1 is installed in the catalyst bed of the deoxygenation treatment device 3. Hydrogen gas blown in by the second gas release device 31 and the washed mixed gas phase entering the deoxygenation treatment device 3 undergo catalytic deoxygenation on the surface of the catalyst bed. The conditions for the deoxygenation process include: reaction space velocity of 3000 h⁻¹. -1 The reaction pressure is 0.3 MPa, and the reaction temperature is 200℃. The resulting mixed gas phase is discharged from the bottom of the deoxygenation treatment device 3 to the second condensation and separation device 4;

[0092] (4) The gaseous product from the second condensation separation device 4 enters the second condensation separation device 4 through the second gaseous inlet. After condensation separation, the condensate obtained is discharged through the bottom of the second condensation separation device 4 for recycling. The remaining explosion suppression gas obtained by separation is discharged through the top of the second condensation separation device 4 and enters the first condensation separation device 1 through the circulation device 5 for recycling.

[0093] Example 2

[0094] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-2 prepared in Preparation Example 2 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0095] Example 3

[0096] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-3 prepared in Preparation Example 3 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0097] Example 4

[0098] This embodiment is carried out in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-4 prepared in Preparation Example 4 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0099] Example 5

[0100] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-5 prepared in Preparation Example 5 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0101] Example 6

[0102] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-6 prepared in Preparation Example 6 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0103] Example 7

[0104] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-7 prepared in Preparation Example 7 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0105] Example 8

[0106] This embodiment is implemented in accordance with the manner of Example 1, except that in step (3), the catalyst Cat-8 prepared in Preparation Example 8 is installed in the catalyst bed in the deoxygenation treatment device 3.

[0107] Example 9

[0108] This embodiment is implemented in accordance with the manner of embodiment 1, except that in step (1), the oxygen content in the diluted oxygen-containing tail gas is 3% and the helium content is 97%.

[0109] Example 10

[0110] This embodiment is implemented in accordance with the manner of embodiment 1, except that in step (2), the ratio of the flow rate of the diluted oxygenated tail gas to the flow rate of the detergent methanol is 1:10.

[0111] Example 11

[0112] This embodiment is implemented in accordance with the manner of Embodiment 1, except that in step (3), the reaction conditions include: reaction space velocity of 2000 h⁻¹. -1 The reaction pressure was 0.5 MPa and the reaction temperature was 250℃.

[0113] Comparative Example 1

[0114] The comparative example was carried out in accordance with Example 1, except that in step (3), the reaction conditions included a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 1.0 MPa and the reaction temperature was 300℃.

[0115] Comparative Example 2

[0116] The comparative example was carried out in accordance with the preparation method of Example 1, except that the auxiliary precursors were NaNO3 and Fe(NO3)3, respectively, to prepare the catalyst for the catalytic reaction of the present invention, designated as D-Cat-1, wherein the weight ratio of Pd in ​​Pd(NO3)2, Na in NaNO3 and Fe in Fe(NO3)3 to the support was 0.3:3:10:100.

[0117] The oxygen-containing tail gas from the preparation of epichlorohydrin by hydrogen peroxide method is treated in accordance with the method of Example 1, except that in step (3), D-Cat-1 is installed in the catalyst bed of the deoxygenation treatment device 3.

[0118] Test case

[0119] The stability and deoxygenation efficiency of Examples 9-19 and Comparative Examples 1 and 2 were detected in real time using gas chromatography online.

[0120] The deoxygenation rates in the examples and comparative examples were calculated, and the results are shown in Table 1. The calculation method is as follows:

[0121] The results are shown in Table 1.

[0122] Table 1

[0123]

[0124]

[0125] As shown in Table 1, using the technical solution described in this invention, the deoxygenation rates of Examples 1-10 are all above 80%, achieving good deoxygenation effects at relatively low catalytic temperatures. Furthermore, the method described in this invention can essentially achieve complete recovery and recycling of the anti-explosion gas in the oxygen-containing tail gas, reducing production costs and decreasing the amount of VOCs to be treated in the oxygen-containing tail gas, making it safer and more environmentally friendly. In contrast, the catalytic temperature and reaction space velocity of Comparative Example 1 are higher, and the catalyst prepared in Comparative Example 2 has poor chlorine resistance, resulting in a lower deoxygenation efficiency than the method described in this application, thereby increasing the treatment cost of oxygen-containing tail gas from the preparation of epichlorohydrin using the hydrogen peroxide method.

[0126] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for treating oxygen-containing tail gas from the hydrogen peroxide method for preparing epichlorohydrin, characterized in that, The method includes: condensing and separating the oxygen-containing tail gas generated from the preparation of epichlorohydrin by hydrogen peroxide method, diluting the gas phase obtained after condensation and separation with an explosion suppressant gas, washing the resulting mixed gas phase, and then deoxygenating the washed mixed gas phase in the presence of a catalyst and a reducing gas. The catalyst contains a support and an active component and an auxiliary agent supported on the support. The active component is at least one of the oxides of Pd, Pt, Ru, and Rh, and the auxiliary agent is at least one of the oxides of Zn, Na, K, Mg, and Cu.

2. The method according to claim 1, characterized in that, In the oxygen-containing tail gas generated during the preparation of epichlorohydrin by the hydrogen peroxide method, the oxygen content is 85-98% by volume, the allyl chloride content is 1-10% by volume, and the epichlorohydrin content is 0.1-1% by volume.

3. The method according to claim 1 or 2, characterized in that, The explosion suppression gas is selected from at least one of nitrogen, helium, argon and methane; Preferably, in the diluted mixed gas phase, the volume ratio of oxygen to the explosion-suppressing gas is 1:20-90.

4. The method according to claim 1, characterized in that, The detergent used in the washing process is at least one of ethanol, ethylene glycol, methanol, and deionized water; Preferably, the volume ratio of the detergent to the mixed gas phase is 1:5-30.

5. The method according to any one of claims 1-4, characterized in that, The weight ratio of the active component, the auxiliary agent, and the carrier is 0.01-1:1-20:

100.

6. The method according to claim 1 or 5, characterized in that, The carrier is selected from at least one of alumina, ceramics, zeolite molecular sieves, silicon dioxide, and activated carbon.

7. The method according to any one of claims 1-6, characterized in that, The deoxygenation treatment conditions include: a temperature of 120-300℃, a pressure of 0.1-1 MPa, and a reaction space velocity of 1500-4500 h⁻¹. -1 .

8. The method according to claim 1, characterized in that, The reducing gas is selected from at least one of hydrogen, carbon monoxide, propane, and chloropropane; Preferably, the molar ratio of oxygen to the reducing gas in the washed mixed gas phase is 1:2-10.

9. The method according to any one of claims 1-8, characterized in that, The method is implemented in an exhaust gas treatment system, which includes a first condensation separation device (1), a washing device (2), and a deoxygenation treatment device (3) connected in sequence. The first condensation separation device (1) is equipped with a first gas release device (11). After the oxygen-containing tail gas enters the first condensation separation device (1), it is condensed and separated. The explosion suppression gas delivered by the first gas release device (11) is used to dilute the gas phase obtained after condensation separation to obtain a mixed gas phase. The washing device (2) is equipped with a liquid release device (21), and the washing agent provided by the liquid release device (21) is used to wash the mixed gas phase from the first condensation separation device (1) to obtain the washed mixed gas phase. The deoxygenation treatment device (3) is equipped with a second gas release device (31) and a heating device for heating the material in the deoxygenation treatment device (3). The mixed gas phase after washing from the washing device (2) is mixed and reacted with the reducing gas entering through the second gas release device (31).

10. The method according to claim 9, characterized in that, The exhaust gas treatment system also includes a second condensation separation device (4) and a circulation device (5). The reaction products from the deoxygenation treatment device (3) are condensed and separated in the second condensation separation device (4), and the separated gas phase is returned to the first condensation separation device (1) for recycling through the circulation device (5).

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