A waste incinerator flue gas treatment process

Abstract

The application discloses a waste incinerator flue gas treatment process, which uses a core-shell structure catalyst with internal and external function division to catalytically oxidize and synchronously remove CO, non-methane total hydrocarbon and dioxin in waste incinerator flue gas; the core-shell structure catalyst with internal and external function division comprises an inner core capable of catalytically oxidizing and removing CO and non-methane total hydrocarbon and an outer shell capable of catalytically decomposing dioxin; the inner core is a mesoporous Co-M mixed oxide nanorod, wherein M is at least one of La, Ce and Pr; and the outer shell is a macroporous N-HZSM-5 molecular sieve, wherein N is at least one of Pt, Pd and Ru. The catalyst can well solve the problems of synchronous one-off catalytic removal of flue gas pollutants such as CO, non-methane total hydrocarbon and dioxin and chlorine poisoning of the catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of complex flue gas treatment, and particularly relates to a waste incinerator flue gas treatment process. BACKGROUND

[0002] With the development of cities and population growth, the amount of municipal solid waste is steadily increasing year by year, and the widely used waste treatment methods at present are sanitary landfill, incineration and composting, among which the incineration method has the highest degree of harmlessness, reduction and resource utilization.

[0003] Although incineration of waste can avoid some pollution caused by landfill, the incineration process of waste will inevitably produce a large amount of gaseous pollutants, such as a large amount of CO, VOCs, NO x , SO2 and dust. Kitchen and other household wastes contain different concentrations of chloride ions, which produce more toxic chlorinated organic compounds (such as chlorobenzene, dioxin, etc.), which are difficult to treat and can easily cause huge environmental pollution. In the traditional pharmaceutical and chemical industry, a large amount of organic solvents containing chlorine and not containing chlorine are used in the production process, and the tail gas discharged also has the characteristics of mixed with such chlorinated organic compounds and non-chlorinated organic compounds.

[0004] For the compounds such as CO, VOCs and chlorinated organic compounds which are flammable, catalytic degradation technology is one of the preferred treatment processes, which is considered as an effective means for treating CO, VOCs and chlorinated organic compounds, and is widely concerned by domestic and foreign experts and scholars. It has the characteristics of low conversion temperature, high treatment efficiency and not easy to produce secondary pollution, and is one of the most effective end treatment technologies for many flammable gases.

[0005] The patent specification with publication number CN109772347B discloses a sulfur-tolerant CO catalytic combustion agent for FCC production process and a preparation method thereof. The catalyst contains copper cerium zirconium magnesium composite oxide supported on alumina, and also contains heat stability additives such as zirconium and sulfur poisoning resistance additives such as magnesium. It has high CO catalytic combustion activity (CO conversion rate 100%), high hydrothermal stability and effectively inhibits the generation of NO x in flue gas, and also has sulfur poisoning resistance. However, the catalyst is only suitable for FCC production process, and does not have the performance of synergistic treatment of other gaseous pollutants.

[0006] The patent specification with publication number CN104549231B discloses a catalyst for catalytic degradation of dioxin generated in waste incineration tail gas and a preparation method thereof. The catalyst takes carbon nanotubes as the main carrier, and takes VO x , WO x , MnO xTiO2 is the main active catalytic component, and the honeycomb catalyst is prepared by extrusion molding, and then dried and activated.

[0007] The patent specification with publication number CN109126773B discloses a catalyst for waste incineration flue gas purification, which uses vanadium pentoxide, platinum oxide and tungsten oxide as active components, gamma-alumina, titanium dioxide and carbon nanotubes as carriers, and one or more of manganese oxide, iron oxide, copper oxide, tin oxide and cerium oxide as active additives. The catalyst has the functions of decomposing dioxins and chlorobenzene compounds, and also has the functions of denitrification and sulfur resistance, and still has effects on dioxins, NO x It has excellent removal capacity.

[0008] The patent specification with publication number CN113333015B discloses a chlorine-containing organic waste gas catalytic combustion catalyst with high carbon dioxide selectivity and a preparation method thereof. The catalyst uses HZSM-5 molecular sieve as the carrier, and loads copper oxide, niobium oxide and cerium oxide as active components, wherein the molar ratio of Cu:Nb:Ce is 0.25-0.75:0.5-1:0.25-1.5. The niobium oxalate, copper nitrate and cerium nitrate are dissolved in deionized water, then the HZSM-5 molecular sieve is added, and after sufficient impregnation, drying and calcination at 550℃, the chlorine-containing organic waste gas catalytic combustion catalyst with high carbon dioxide selectivity is obtained.

[0009] Therefore, catalytic degradation technology is a high-efficiency treatment process for flammable gas pollutants such as CO, VOCs and dioxins. However, most existing catalytic degradation processes are single objects or the same type of gaseous components, and the catalyst components for treating CO, VOCs and dioxins are quite different, and the catalyst cannot be universal.

[0010] The catalytic oxidation reaction process of dioxin and other chlorine-containing VOCs can be roughly divided into three steps: (1) pollutants molecules or dioxin-absorbed fine particles are intercepted on the surface of the catalyst, dissociate and dechlorinate (C-Cl bond breaks) to form intermediate species, HCl and Cl2; (2) the intermediate species are further deeply oxidized by active oxygen species to generate CO2 and H2O (3) the dissociated HCl and Cl2 chlorine species are removed from the surface of the catalyst. The noble metal-loaded molecular sieve and other materials are used as catalysts for the catalytic oxidation of chlorine-containing organic waste gas, and the catalytic degradation performance is superior. The noble metal-loaded molecular sieve has rich acid sites, which can be used as adsorption and dechlorination sites for pollutants, however, this type of catalyst does not have the ability to catalytically oxidize CO and other VOCs, in addition, the accumulation of chlorine-containing species and intermediate products on the acid sites can easily cause catalyst poisoning. Transition metal oxides such as Co3O4 have excellent redox performance, which can realize the deep oxidation of CO, VOCs and other carbon-containing intermediate products. However, transition metal oxides have strong adsorption capacity for chlorine species and can react with chlorine species to generate metal chlorides, which can cause serious chlorine poisoning of the catalyst. Therefore, how to realize the catalytic degradation of different types of flue gas pollutants through the structural design of the catalyst to realize the function of different zones is a big challenge for the current waste incinerator and other flue gas containing multiple flue gas pollution components. SUMMARY

[0011] In view of the above technical problems and the deficiencies in the field, the present application provides a waste incinerator flue gas treatment process, which solves the problem of simultaneous one-time catalytic removal of CO, non-methane total hydrocarbon and dioxin and other flue gas pollutants emitted in large quantities under the condition of incomplete combustion of the waste incinerator. The traditional catalyst for removing dioxin in flue gas is mainly a vanadium-based catalyst, and CO and non-methane total hydrocarbon generated by incomplete combustion of the waste incinerator cannot be effectively degraded on the vanadium-based catalyst. At the same time, the adsorption and insufficient degradation of CO and non-methane total hydrocarbon on the surface of the catalyst can cause the catalyst to be rapidly deactivated due to surface carbon accumulation, and the vanadium-based catalyst has insufficient dioxin removal capacity under the condition of coexistence of other volatile organic compounds.

[0012] The technical solutions adopted by the present application are as follows:

[0013] A waste incinerator flue gas treatment process uses a core-shell structure catalyst with internal and external functional zones to catalytically oxidize and simultaneously remove CO, non-methane total hydrocarbon and dioxin in the flue gas of the waste incinerator;

[0014] The core-shell structure catalyst with internal and external functional zones includes an inner core that can catalytically oxidize and remove CO and non-methane total hydrocarbon, and an outer shell that can catalytically decompose dioxin;

[0015] The inner core is a mesoporous Co-M mixed oxide nanorod (wherein Co exists in the form of Co3O4), wherein M is at least one of La, Ce, Pr;

[0016] The outer shell is a macroporous N-HZSM-5 molecular sieve, wherein N is at least one of Pt, Pd, Ru.

[0017] Dioxins and polychlorinated biphenyls in incineration flue gas are adsorbed in fine particulate matters. Traditional catalysts cannot effectively contact with fine particulate matters, and the interception efficiency is also low. Not only the degradation efficiency of dioxins is low, but also poisoning is easily caused. In the core-shell structure catalyst with internal and external functional partition, the N-HZSM-5 molecular sieve in the shell layer has a macroporous structure, which is suitable for the interception and in-situ contact of fine particulate matters. Meanwhile, the outer shell has abundant acid sites, and the interception, adsorption of dioxins and the rupture of C-Cl can be efficiently completed on the catalyst in the layer, and the generation and adsorption of degradation products HCl and Cl2 also occur on the surface of the catalyst shell. The Co-M mixed oxide nanorod inner core ensures the superior redox performance of the catalytic system, which can realize the deep oxidation of CO, non-methane total hydrocarbons and dioxin degradation intermediates, and avoid the attack of chloride ions on Co3O4 and La, Ce, Pr oxides. Through the design of the macroporous structure of the catalyst shell, the interception of fine particulate matters adsorbing dioxins and the adsorption of other macromolecular chlorine-containing VOCs can be realized, and the mesoporous structure of the inner core ensures that CO, non-methane total hydrocarbons and dioxin degradation intermediates can effectively diffuse to the surface of the active center of the catalyst, realizing the efficient degradation of various pollution components in the flue gas by the catalyst.

[0018] In a preferred embodiment, the mass ratio of the inner core to the outer shell is 0.35-4:1.

[0019] In a preferred embodiment, the mass ratio of Co to M in the mesoporous Co-M mixed oxide nanorod is 1:0.05-0.5.

[0020] In a preferred embodiment, the specific surface area of the mesoporous Co-M mixed oxide nanorod is 5-20 m 2 / g.

[0021] In a preferred embodiment, the length of the mesoporous Co-M mixed oxide nanorod is 1-30 μm, and the width is 0.5-1 μm.

[0022] In a preferred embodiment, the mesopore size of the mesoporous Co-M mixed oxide nanorod is 2-10 nm.

[0023] The mesoporous Co-M mixed oxide nanorod can be prepared by a uniform hydrothermal method.

[0024] In a preferred embodiment, the method for preparing the mesoporous Co-M mixed oxide nanorod comprises: preparing a mixed aqueous solution of cobalt chloride hexahydrate, nitrate of M and urea and performing a uniform hydrothermal treatment, cooling, and washing the obtained solid with water and drying to obtain the mesoporous Co-M mixed oxide nanorod.

[0025] In a preferred embodiment, in the method for preparing the mesoporous Co-M mixed oxide nanorod, the mass ratio of the cobalt chloride hexahydrate to the urea is 1:5-50.

[0026] In a preferred embodiment, in the method for preparing the mesoporous Co-M mixed oxide nanorod, the uniform hydrothermal treatment is performed in a polytetrafluoroethylene-lined hydrothermal kettle, and the filling degree of the polytetrafluoroethylene-lined hydrothermal kettle is 50%-80%.

[0027] In a preferred embodiment, in the method for preparing the mesoporous Co-M mixed oxide nanorod, the temperature of the uniform hydrothermal treatment is 100-200°C.

[0028] In a preferred embodiment, in the method for preparing the mesoporous Co-M mixed oxide nanorod, the time of the uniform hydrothermal treatment is 10-100 hours.

[0029] In a preferred embodiment, in the method for preparing the mesoporous Co-M mixed oxide nanorod, the temperature of the drying is lower than the temperature of the hydrothermal treatment. Further, the temperature of the drying can be 60-80°C.

[0030] The macroporous N-HZSM-5 molecular sieve is prepared by a microwave hydrothermal method.

[0031] In a preferred embodiment, in the macroporous N-HZSM-5 molecular sieve, the mass ratio of HZSM-5 to N is 1:0.001-0.05.

[0032] In a preferred embodiment, the specific surface area of the macroporous N-HZSM-5 molecular sieve is 200-300 m 2 / g.

[0033] In a preferred embodiment, the extragranular diameter of the macroporous N-HZSM-5 molecular sieve is 0.2-0.6 μm.

[0034] In a preferred embodiment, the macropore size of the macroporous N-HZSM-5 molecular sieve is 50-300 nm.

[0035] The N-HZSM-5 molecular sieve with the large pore structure is formed by secondary crystallization on the Co-M mixed oxide nanorod with the mesoporous structure based on the hotspot effect of the microwave hydrothermal method. The Co-M nanorod has excellent microwave absorption function and can be quickly heated to form a regional hotspot in a microwave field. The precursors in the solution can be quickly crystallized at the regional hotspot, so as to form the N-HZSM-5 crystal on the surface of the Co-M nanorod.

[0036] In a preferred embodiment, the preparation method of the core-shell structure catalyst with internal and external functional partitioning comprises the following steps:

[0037] S1, in deionized water, sodium chloride, polyethylene glycol, tetrapropylammonium hydroxide and aluminum isopropoxide are added in sequence while stirring to obtain a first mixture;

[0038] S2, the first mixture is ultrasonically treated for 10-40 minutes, and then stirred for 5-20 minutes, and then the soluble salt of N is quickly added to the first mixture while stirring, and finally the Co-M mixed oxide nanorod with the mesoporous structure is added, and stirred at room temperature for 20-40 hours to obtain a second mixture;

[0039] S3, the second mixture is transferred to a polytetrafluoroethylene hydrothermal kettle, and two-step hydrothermal reactions are carried out in a microwave hydrothermal reactor, i.e., first reacted at 60-200℃ for 0.5-8 hours, and then reacted at 120-200℃ for 1-16 hours, and the solid obtained by hydrothermal reaction is washed, dried and calcined at 300-600℃ for 1-5 hours to obtain the core-shell structure catalyst with internal and external functional partitioning.

[0040] In a preferred embodiment, in the preparation method of the core-shell structure catalyst with internal and external functional partitioning, the mass ratio of deionized water, sodium chloride, polyethylene glycol, tetrapropylammonium hydroxide, aluminum isopropoxide, and tetraethyl orthosilicate is 100:1-5:5-10:10-30:0.1-1.0:10-20.

[0041] In a preferred embodiment, in the preparation method of the core-shell structure catalyst with internal and external functional partitioning, the filling degree of the polytetrafluoroethylene hydrothermal kettle is 30-75%.

[0042] In an embodiment, in the waste incinerator flue gas treatment process, the amount of the core-shell structure catalyst with internal and external functional partitioning is 40000-100000h -1 -1, the temperature of the waste incinerator flue gas is 170-400℃, the concentration of CO in the waste incinerator flue gas is 500-50000mg / m 3 , the concentration of non-methane total hydrocarbon in the waste incinerator flue gas is 20-2000mg / m 3 , and the concentration of dioxin in the waste incinerator flue gas is 0.2-5ng / m 3The waste incinerator flue gas treatment process has a CO removal rate of 90% to 99%, a non-methane total hydrocarbon removal rate of 90% to 95%, and a dioxin removal rate of 90% to 95%.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] The waste incinerator flue gas treatment process of the present application uses a shell-core hierarchical pore macro-mesopore structure catalyst with outer and inner functional partitions, wherein the N-HZSM-5 molecular sieve shell has abundant acid sites and a large pore structure, providing interception sites and adsorption sites for fine particulate matter containing dioxin and large molecules of chlorine-containing VOCs, and enabling the C-Cl of the pollutant molecules to be broken; and the Co-M mixed oxide nanorod core has excellent redox performance and a suitable mesopore structure, enabling the deep oxidation of CO, non-methane total hydrocarbon and dioxin degradation intermediates to be further achieved. HCl and Cl2 are mainly generated on the acid sites on the surface of the N-HZSM-5 molecular sieve shell, and the unique structure of the core material can promote rapid dechlorination on the surface of the catalyst, so that the catalyst has good resistance to chlorine poisoning. At the same time, the molecular sieve shell in the core-shell structure can prevent the Co-M mixed oxide nanorod core from directly contacting dioxin, reducing the generation of polychlorinated by-products. This type of catalyst can well solve the problems of simultaneous one-time catalytic removal of gaseous pollutants such as CO, non-methane total hydrocarbon and dioxin, and chlorine poisoning of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 A scanning electron microscope (SEM) photo of the Co-M nanorod prepared by the homogeneous hydrothermal method for Example 1.

[0046] Figure 2 A SEM photo of the Co-M@N-HZSM-5 core-shell structure catalyst prepared by the homogeneous hydrothermal method and the microwave hydrothermal method for Example 1. DETAILED DESCRIPTION

[0047] The present application will be further described below in conjunction with the drawings and specific examples. It should be understood that these examples are only used to illustrate the present application and are not used to limit the scope of the present application.

[0048] Example 1:

[0049] Preparation of mesoporous Co-La mixed oxide nanorods: raw material mass CoCl2·6H2O: lanthanum nitrate: water: urea = 1:0.1:300:6. Dissolve cobalt chloride hexahydrate and lanthanum nitrate in deionized water, then add urea to the solution and stir for 20 minutes, then pour into a polytetrafluoroethylene-lined hydrothermal kettle at 110℃ for 12 hours of hydrothermal treatment, and the filling degree of the hydrothermal kettle is 70%. The precipitate after hydrothermal treatment is washed with deionized water and anhydrous ethanol, and then the sample is dried at 80℃.Figure 1 SEM images of the mesoporous Co-La mixed oxide nanorods of the present embodiment are shown.

[0050] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 8.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, followed by adding 0.4 g of aluminum isopropoxide. The mixture was then treated with ultrasound in an ultrasonic instrument for 15 minutes, and after stirring for 10 minutes, 13.08 g of tetraethyl orthosilicate was quickly added into the solution under stirring, followed by adding 0.02 g of H2PtCl6, and finally adding 1.2 g of the mesoporous Co-La mixed oxide nanorods, and stirring at room temperature for 24 h. After completion of the stirring, the above mixture was transferred into a polytetrafluoroethylene hydrothermal kettle, with a filling degree of 40%, and subjected to two-step hydrothermal reaction in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 1 h, and then at 170°C for 2 h. The hydrothermally obtained reaction product was dried at 80°C after filtration and washing, and calcined at 400°C for 2 hours to obtain the finished catalyst, i.e. the core-shell structure catalyst with internal and external functional partition. Figure 2 SEM images of the core-shell structure catalyst with internal and external functional partition of the present embodiment are shown.

[0051] The above core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 350°C, a gas flow of 500 m 3 / h, a CO concentration of 5000 mg / m 3 , a non-methane total hydrocarbon concentration of 200 mg / m 3 , and a dioxin concentration of 2 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 40000 h -1 . The removal efficiency of CO generated by combustion was 95%, the removal rate of non-methane total hydrocarbon generated by combustion was 92.3%, and the removal efficiency of dioxin in the flue gas was 94.9%.

[0052] Example 2:

[0053] Preparation of mesoporous Co-Ce mixed oxide nanorods: raw materials CoCl2·6H2O: Ce(NO3)3: water: urea = 1:0.2:300:10. Cobalt chloride hexahydrate and cerium nitrate were dissolved in deionized water, and then urea was added into the solution and stirred for 30 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, with a filling degree of the hydrothermal kettle of 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 60°C.

[0054] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate was quickly added into the solution under stirring, 0.025 g of PdCl2 was added, and finally 1.2 g of mesoporous Co-Ce mixed oxide nanorods were added, and stirred at room temperature for 24 h. After stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 1.5 h, and then at 170°C for 3 h. The hydrothermally obtained reaction product was filtered, washed, and dried at 60°C, and the catalyst product was obtained by calcining at 400°C for 2 hours, i.e. the core-shell structure catalyst with internal and external functional partition.

[0055] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 300°C, a gas flow of 5000 m 3 / h, a CO concentration of 10000 mg / m 3 , a non-methane total hydrocarbon concentration of 1000 mg / m 3 , and a dioxin concentration of 4 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 40000 h -1 , and the removal efficiency of CO generated by combustion was 96%, the removal rate of non-methane total hydrocarbon generated by combustion was 90.6%, and the removal efficiency of dioxin in the flue gas was 93.5%.

[0056] Example 3:

[0057] Preparation of mesoporous Co-Pr mixed oxide nanorods: raw material mass CoCl2·6H2O: Pr(NO3)3: water: urea = 1:0.3:300:35. Cobalt chloride hexahydrate and praseodymium nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0058] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.03 g of RuCl3·3H2O, and finally 1.2 g of mesoporous Co-Pr mixed oxide nanorods were quickly added into the solution under stirring, and stirred at room temperature for 24 h. After stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was dried at 80°C after filtration and washing, and the catalyst product was obtained by calcining at 400°C for 2 hours, i.e. the core-shell structure catalyst with internal and external functional partition.

[0059] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 270°C, a gas flow of 2000 m 3 / h, a CO concentration of 30000 mg / m 3 , a non-methane total hydrocarbon concentration of 300 mg / m 3 , and a dioxin concentration of 3 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 60000 h -1 , and the removal efficiency of CO generated by combustion was 95.0%, the removal rate of non-methane total hydrocarbon generated by combustion was 90.3%, and the removal efficiency of dioxin in the flue gas was 91.8%.

[0060] Example 4:

[0061] Preparation of mesoporous Co-Pr mixed oxide nanorods: raw material mass CoCl2·6H2O: Pr(NO3)3: water: urea = 1:0.4:300:20. Cobalt chloride hexahydrate and praseodymium nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoroethylene-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0062] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 15 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.05 g of PdCl2, and finally 1.2 g of mesoporous Co-Pr mixed oxide nanorods were quickly added to the solution under stirring, and stirred at room temperature for 24 h. After stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was dried at 80°C after filtration and washing, and the catalyst product was obtained by calcining at 400°C for 2 hours, i.e. the core-shell structure catalyst with internal and external functional partition.

[0063] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas temperature of 200°C, a gas flow of 1000 m 3 / h, a CO concentration of 10000 mg / m 3 , a non-methane total hydrocarbon concentration of 500 mg / m 3 , and a dioxin concentration of 2 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 80000 h -1 , and the removal efficiency of CO generated by combustion was 96.1%, the removal rate of non-methane total hydrocarbon generated by combustion was 91.0%, and the removal efficiency of dioxin in the flue gas was 93.2%.

[0064] Example 5:

[0065] Preparation of mesoporous Co-Ce mixed oxide nanorods: raw material mass CoCl2·6H2O: Ce(NO3)3: water: urea = 1:0.18:300:45. Cobalt chloride hexahydrate and cerium nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0066] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.015 g of RuCl3·3H2O, and finally 1.5 g of mesoporous Co-Ce mixed oxide nanorods were quickly added into the solution under stirring, and stirred at room temperature for 24 h. After stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was filtered, washed, and dried at 60°C, and the catalyst product was obtained by calcining at 400°C for 2 hours, i.e. the core-shell structure catalyst with internal and external functional partition.

[0067] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 210°C, a gas flow of 5000 m 3 / h, a CO concentration of 40000 mg / m 3 , a non-methane total hydrocarbon concentration of 250 mg / m 3 , and a dioxin concentration of 1.1 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 40000 h -1 , and the removal efficiency of CO generated by combustion was 98.0%, the removal rate of non-methane total hydrocarbon generated by combustion was 94.6%, and the removal efficiency of dioxin in the flue gas was 94.9%.

[0068] Example 6:

[0069] Preparation of mesoporous Co-Ce mixed oxide nanorods: raw material mass CoCl2·6H2O: Ce(NO3)3: water: urea = 1:0.15:300:30. Cobalt chloride hexahydrate and cerium nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0070] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.03 g of H2PtCl6, and finally 4.8 g of mesoporous Co-Ce mixed oxide nanorods were quickly added to the solution under stirring, and stirred at room temperature for 24 h. After stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was filtered, washed, and dried at 60°C, and then calcined at 400°C for 2 hours to obtain the finished catalyst, i.e. the core-shell structure catalyst with internal and external functional partition.

[0071] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 280°C, a gas flow of 1000 m 3 / h, a CO concentration of 20000 mg / m 3 , a non-methane total hydrocarbon concentration of 350 mg / m 3 , and a dioxin concentration of 4 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 50000 h -1 , and the removal efficiency of CO generated by combustion was 96.9%, the removal rate of non-methane total hydrocarbon generated by combustion was 94.1%, and the removal efficiency of dioxin in the flue gas was 92.7%.

[0072] Example 7:

[0073] Preparation of mesoporous Co-La mixed oxide nanorods: raw materials CoCl2·6H2O: lanthanum nitrate: water: urea = 1:0.15:300:25. Cobalt chloride hexahydrate and lanthanum nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0074] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.025 g of RuCl3·3H2O, and finally 2.4 g of mesoporous Co-La mixed oxide nanorods were quickly added into the solution under stirring, and stirred at room temperature for 24 h. After the stirring was completed, the above mixture was transferred to a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was dried at 80°C after filtration and washing, and the catalyst product was obtained by calcining at 550°C for 2 hours, i.e. the core-shell structure catalyst with internal and external functional partition.

[0075] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 260°C, a gas flow of 3000 m 3 / h, a CO concentration of 8000 mg / m 3 , a non-methane total hydrocarbon concentration of 500 mg / m 3 , and a dioxin concentration of 3 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 100000 h -1 , and the removal efficiency of CO generated by combustion was 95.2%, the removal rate of non-methane total hydrocarbon generated by combustion was 90.4%, and the removal efficiency of dioxin in the flue gas was 91.1%.

[0076] Example 8:

[0077] Preparation of mesoporous Co-La mixed oxide nanorods: raw materials CoCl2·6H2O: lanthanum nitrate: water: urea = 1:0.25:300:30. Cobalt chloride hexahydrate and lanthanum nitrate were dissolved in deionized water, and then urea was added to the solution and stirred for 20 minutes, and then poured into a polytetrafluoro-lined hydrothermal kettle and hydrothermally treated at 110°C for 12 hours, and the filling degree of the hydrothermal kettle was 70%. The precipitate after hydrothermal treatment was washed with deionized water and anhydrous ethanol, and then the sample was dried at 80°C.

[0078] Preparation of the core-shell structure catalyst: 1.24 g of sodium chloride, 10.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, and then 0.4 g of aluminum isopropoxide was added. Subsequently, the mixture was ultrasonically treated in an ultrasonic instrument for 30 minutes, and after stirring for about ten minutes, 13.08 g of tetraethyl orthosilicate, 0.04 g of PdCl2 and finally 2.4 g of mesoporous Co-La mixed oxide nanorods were quickly added into the solution under stirring, and stirred at room temperature for 24 h. After completion of the stirring, the above mixture was transferred into a polytetrafluoroethylene hydrothermal kettle, the filling degree was 40%, and two-step hydrothermal reaction was carried out in a microwave hydrothermal reactor. The reaction was first carried out at 80°C for 2 h, and then at 170°C for 4 h. The hydrothermally obtained reaction product was filtered, washed and dried at 60°C, and then calcined at 400°C for 2 hours to obtain the catalyst product, i.e. the core-shell structure catalyst with internal and external functional partition.

[0079] The above-mentioned core-shell structure catalyst with internal and external functional partition was used in a waste incinerator flue gas with a temperature of 320°C, a gas flow of 2500 m 3 / h, a CO concentration of 12000 mg / m 3 , a non-methane total hydrocarbon concentration of 250 mg / m 3 , and a dioxin concentration of 2.8 ng / m 3 . The amount of the core-shell structure catalyst was calculated according to the space velocity of 50000 h -1 , and the removal efficiency of CO generated by combustion was 98.5%, the removal rate of non-methane total hydrocarbon generated by combustion was 94.6%, and the removal efficiency of dioxin in the flue gas was 94.7%.

[0080] Comparative Example 1:

[0081] The difference from Example 1 is only that no lanthanum nitrate is added in the preparation process of the nanorods, and no H2PtCl6 is added in the preparation process of the core-shell structure catalyst, and the rest is the same, to obtain a composite catalyst.

[0082] The above-mentioned composite catalyst was used in a waste incinerator flue gas with a temperature of 350°C, a gas flow of 500 m 3 / h, a CO concentration of 5000 mg / m 3 , a non-methane total hydrocarbon concentration of 200 mg / m 3 , and a dioxin concentration of 2 ng / m 3 . The amount of the composite catalyst was calculated according to the space velocity of 40000 h -1 , and the removal efficiency of CO generated by combustion was 83.1%, the removal rate of non-methane total hydrocarbon generated by combustion was 60.5%, and the removal efficiency of dioxin in the flue gas was 30.5%.

[0083] Comparative Example 2:

[0084] The difference from Example 1 is only that no lanthanum nitrate is added in the nanorod preparation process, and the rest is the same, to obtain the composite catalyst.

[0085] The composite catalyst above is used in the waste incinerator flue gas temperature of 350℃, gas flow of 500m 3 / h, CO concentration of 5000mg / m 3 , non-methane total hydrocarbon concentration of 200mg / m 3 , dioxin concentration of 2ng / m 3 ; the composite catalyst is used in the amount of 40000h -1 -1, the removal efficiency of CO produced by combustion is 82.4%, the removal rate of non-methane total hydrocarbon produced by combustion is 67.1%, and the removal efficiency of dioxin in the flue gas is 90.0%.

[0086] Comparative Example 3:

[0087] The difference from Example 1 is only that the ordinary hydrothermal reactor is used instead of the microwave hydrothermal reactor, and the rest is the same, and the composite catalyst obtained has no core-shell structure.

[0088] The composite catalyst above is used in the waste incinerator flue gas temperature of 350℃, gas flow of 500m 3 / h, CO concentration of 5000mg / m 3 , non-methane total hydrocarbon concentration of 200mg / m 3 , dioxin concentration of 2ng / m 3 ; the composite catalyst is used in the amount of 40000h -1 -1, the removal efficiency of CO produced by combustion is 74.3%, the removal rate of non-methane total hydrocarbon produced by combustion is 50.6%, and the removal efficiency of dioxin in the flue gas is 30.2%.

[0089] Comparative Example 4:

[0090] Co-La mixed oxide preparation: raw material mass CoCl2·6H2O: lanthanum nitrate: water: urea = 1:0.1:300:6. Dissolve cobalt chloride hexahydrate and lanthanum nitrate in deionized water, then add urea to the solution and stir for 400 minutes. The precipitate after uniform precipitation is washed with deionized water and anhydrous ethanol, and then the sample is dried at 80℃.

[0091] Preparation of Co-La / Pt-HZSM-5 composite catalyst: 1.24 g of sodium chloride, 8.0 g of polyethylene glycol, 22.5 g of tetrapropylammonium hydroxide were added into 100 mL of deionized water under stirring, followed by adding 0.4 g of aluminum isopropoxide. The mixture was then treated with ultrasonic for 15 minutes, and after stirring for ten minutes, 13.08 g of tetraethyl orthosilicate, 0.03 g of H2PtCl6 and finally 1.2 g of Co-La mixed oxide were added into the solution under stirring at 80 °C for 48 h. The obtained reaction mixture was uniformly precipitated, filtered, washed and dried at 80 °C, and calcined at 400 °C for 2 hours to obtain the composite catalyst.

[0092] Compared with Example 1, the Co-La mixed oxide and the Co-La / Pt-HZSM-5 composite catalyst of the present comparative example were both prepared by the uniform precipitation method, and were metal oxide mixture catalysts.

[0093] The above composite catalyst was used in a waste incinerator flue gas with a temperature of 350 °C, a gas flow of 500 m 3 / h, a CO concentration of 5000 mg / m 3 , a non-methane total hydrocarbon concentration of 200 mg / m 3 , and a dioxin concentration of 2 ng / m 3 . The amount of the composite catalyst was calculated according to the space velocity of 40000 h -1 , and the removal efficiency of the CO generated by combustion was 76.2%, the removal efficiency of the non-methane total hydrocarbon generated by combustion was 65.8%, and the removal efficiency of the dioxin in the flue gas was 40.2%.

[0094] Furthermore, it is to be understood that various alterations and modifications can be made to the application herein disclosed in the above description, within the scope of the appended claims, and it is intended to cover in the claims all such alterations and modifications of the application.

Claims

1. A process for treating flue gas from a waste incinerator, characterized in that, The application discloses a core-shell structure catalyst with internal and external functional division for catalyzing oxidation to simultaneously remove CO, non-methane total hydrocarbon and dioxin in flue gas of a waste incinerator; The core-shell structure catalyst with internal and external functional division comprises an inner core capable of catalyzing oxidation to remove CO and non-methane total hydrocarbon and an outer shell capable of catalyzing decomposition of dioxin; and the mass ratio of the inner core to the outer shell is 0.35-4:

1. The core is a mesoporous Co-M mixed oxide nanorod, wherein M is at least one of La, Ce and Pr; the mass ratio of Co to M in the mesoporous Co-M mixed oxide nanorod is 1:0.05-0.5; the specific surface area of the mesoporous Co-M mixed oxide nanorod is 5-20 m 2 / g; the length of the mesoporous Co-M mixed oxide nanorod is 1-30 μm, the width is 0.5-1 μm; the mesopore size of the mesoporous Co-M mixed oxide nanorod is 2-10 nm. The shell is a N-HZSM-5 molecular sieve with a large pore structure, wherein N is at least one of Pt, Pd and Ru; the specific surface area of the N-HZSM-5 molecular sieve with the large pore structure is 200-300 m 2 / g; the external diameter of the N-HZSM-5 molecular sieve with the large pore structure is 0.2-0.6 μm; and the large pore size of the N-HZSM-5 molecular sieve with the large pore structure is 50-300 nm. The preparation method of the core-shell structure catalyst with internal and external functional division comprises the following steps: S1, sodium chloride, polyethylene glycol, tetrapropylammonium hydroxide and aluminum isopropyl alcohol are sequentially added into deionized water while stirring to obtain a first mixture; S2, the first mixture is ultrasonically treated for 10-40 minutes, and then stirred for 5-20 minutes; a soluble salt of N is quickly added into the first mixture while stirring; finally, the mesoporous Co-M mixed oxide nanorod is added into the first mixture while stirring, and the mixture is stirred at room temperature for 20-40 hours to obtain a second mixture; S3, the second mixture is transferred into a polytetrafluoroethylene hydrothermal kettle, and two-step hydrothermal reactions are carried out in a microwave hydrothermal reactor, i.e., the mixture is first reacted at 60-200 DEG C for 0.5-8 hours, and then reacted at 120-200 DEG C for 1-16 hours; the solid obtained through the hydrothermal reaction is washed, dried and calcined at 300-600 DEG C for 1-5 hours to obtain the core-shell structure catalyst with internal and external functional division.

2. The waste incinerator flue gas treatment process according to claim 1, characterized in that, The preparation method of the mesoporous Co-M mixed oxide nanorod comprises the following steps: a mixed aqueous solution of cobalt chloride hexahydrate, a nitrate of M and urea is prepared and subjected to uniform hydrothermal treatment, and the obtained solid is washed with water and dried to obtain the mesoporous Co-M mixed oxide nanorod.

3. The waste incinerator flue gas treatment process according to claim 2, characterized in that, In the preparation method of the mesoporous Co-M mixed oxide nanorod, The mass ratio of the cobalt chloride hexahydrate to the urea is 1:5-50; The uniform hydrothermal treatment is carried out in a polytetrafluoroethylene lining hydrothermal kettle, and the filling degree of the polytetrafluoroethylene lining hydrothermal kettle is 50%-80%; The temperature of the uniform hydrothermal treatment is 100-200 DEG C; The time of the uniform hydrothermal treatment is 10-100 hours; The drying temperature is lower than the temperature of the hydrothermal treatment.

4. The waste incinerator flue gas treatment process according to claim 3, characterized in that, In the preparation method of the mesoporous Co-M mixed oxide nanorod, the drying temperature is 60-80 DEG C.

5. The waste incinerator flue gas treatment process according to claim 1, characterized in that, The mass ratio of HZSM-5 to N in the macroporous N-HZSM-5 molecular sieve is 1:0.001-0.

05.

6. The waste incinerator flue gas treatment process according to claim 1, characterized in that, In the preparation method of the core-shell structure catalyst with internal and external functional division, The mass ratio of deionized water, sodium chloride, polyethylene glycol, tetrapropylammonium hydroxide, aluminum isopropyl alcohol, tetraethyl orthosilicate is 100:1-5:5-10:10-30:0.1-1.0:10-20; The filling degree of the polytetrafluoroethylene hydrothermal kettle is 30-75%.

7. The waste incinerator flue gas treatment process according to claim 1, characterized in that, The amount of core-shell structure catalyst used in the inner and outer functional zones is based on a space velocity of 40,000–100,000 h⁻¹. -1 The temperature of the flue gas from the waste incinerator is 170–400℃; the CO concentration in the flue gas is 500–50000 mg / m³. 3 The concentration of non-methane total hydrocarbons is 20–2000 mg / m³. 3 The dioxin concentration is 0.2–5 ng / m³. 3 The waste incinerator flue gas treatment process described above has a CO removal rate of 90%–99%, a non-methane total hydrocarbon removal rate of 90%–95%, and a dioxin removal rate of 90%–95%.

Images