CN113877603A

CN113877603A - Monolithic catalyst, process for producing the same, and process for purifying exhaust gas containing bromine-containing organic substance

Info

Publication number: CN113877603A
Application number: CN202010627365.2A
Authority: CN
Inventors: 蒋见; 缪长喜; 卢媛娇; 孙清
Original assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Current assignee: China Petroleum and Chemical Corp; Sinopec Shanghai Research Institute of Petrochemical Technology
Priority date: 2020-07-01
Filing date: 2020-07-01
Publication date: 2022-01-04
Anticipated expiration: 2040-07-01
Also published as: CN113877603B

Abstract

The invention relates to the technical field of catalytic combustion and environmental protection, and discloses an integral catalyst, a preparation method thereof and a method for purifying waste gas containing bromine-containing organic matters, wherein the catalyst comprises an integral carrier containing an alumina coating, and a noble metal active component and a non-noble metal active component which are loaded on the integral carrier; wherein, the non-noble metal active component is a composite oxide containing cobalt oxide and cerium oxide and/or copper oxide; the cobalt oxide contains Co³⁺And Co²⁺Said Co³⁺And Co²⁺In a molar ratio of 0.85 to 2.2: 1. the monolithic catalyst has higher halogen toxicity resistance and stability, and can be used for purifying waste gas containing bromine-containing organic matters at lower reaction temperatureStill has higher catalytic activity and selectivity.

Description

Monolithic catalyst, process for producing the same, and process for purifying exhaust gas containing bromine-containing organic substance

Technical Field

The invention relates to the technical field of catalytic combustion environmental protection, in particular to an integral catalyst, a preparation method thereof and a method for purifying waste gas containing bromine-containing organic matters.

Background

Petrochemical production processes often produce waste gases containing volatile organic compounds, which if discharged directly into the atmosphere, can cause significant damage to the atmospheric environment. Most volatile organic compounds have peculiar smell and cause pathological changes and even carcinogenesis to human bodies; in particular, the volatile organic waste gas containing halogen has high toxicity, and can generate photochemical reaction with ozone to generate photochemical smog, thereby greatly damaging the global environment.

The domestic and foreign treatment methods for volatile organic compounds are mainly classified into physical methods and chemical methods. The physical method comprises an adsorption method, a condensation method, a membrane separation method and the like, which is a non-destructive method and has the advantages that volatile organic compounds can be recycled, but the treatment is not thorough, and secondary pollution is easily caused; the chemical method mainly includes a direct thermal combustion method, a catalytic combustion method, and the like. The chemical method is characterized by thorough treatment. The thermal combustion method is to crack harmful substances in the tail gas at high temperature, the thermal cracking temperature is as high as 800-900 ℃, the method needs to consume a large amount of fuel oil, the operation cost is high, the energy consumption is high, the removal rate of halogen-containing organic matters is low, and nitrogen oxides can be generated. Whereas the catalytic combustion method lowers the operation temperature by the action of the catalyst, the activity of the catalyst is not high at a lower temperature.

The catalysts for catalytic combustion mainly comprise: noble metal type catalysts, such as Pt, Pd, Rh, etc., which generally have high activity, but have poor halogen resistance and are easily poisoned, resulting in poor stability, and meanwhile, the resources are rare and the price is expensive; single metal oxide catalysts, such as copper, manganese, cobalt and other metal oxides, are relatively low in cost but generally active; the catalytic activity and the anti-toxicity of the composite oxide catalyst are higher than those of the corresponding single oxide, for example, CN103252242B discloses a catalytic combustion catalyst of the composite oxide of copper, manganese and cerium, but the catalytic activity of the catalyst is still lower and the reaction temperature is higher.

Disclosure of Invention

The invention aims to overcome the problems of high catalytic reaction temperature, low catalyst activity, poor antitoxic property and poor stability in the prior art, and provides a monolithic catalyst, a preparation method thereof and a method for purifying waste gas containing bromine-containing organic matters.

In order to achieve the above object, the present invention provides, in one aspect, a monolithic catalyst comprising a monolithic support comprising an alumina coating layer and a noble metal active component and a non-noble metal active component supported on the monolithic support;

wherein, the non-noble metal active component is a composite oxide containing cobalt oxide and cerium oxide and/or copper oxide;

the cobalt oxide contains Co³⁺And Co²⁺Said Co³⁺And Co²⁺In a molar ratio of 0.85 to 2.2: 1.

in a second aspect, the present invention provides a process for preparing a monolithic catalyst, the process comprising:

(1) coating the slurry containing the alumina and/or the alumina precursor on the monolithic carrier, and then drying and/or roasting to obtain the monolithic carrier containing the alumina coating;

(2) loading a composite oxide containing cobalt oxide and cerium oxide and/or copper oxide and a noble metal active component on an integral carrier containing an alumina coating;

in a third aspect of the present invention, there is provided a monolithic catalyst produced by the production method described in the second aspect.

In a fourth aspect of the present invention, there is provided a method for purifying an exhaust gas containing a bromine-containing organic substance, comprising reacting an exhaust gas containing a bromine-containing organic substance in contact with the monolithic catalyst of the first or third aspect in an oxygen-containing atmosphere.

By adopting the technical scheme, the prepared monolithic catalyst has higher halogen toxicity resistance and stability, still has higher catalytic activity and selectivity when being used for catalytic combustion of waste gas containing bromine-containing organic matters at lower reaction temperature, and can still enable the conversion rates of methyl acetate, p-xylene and dibromomethane to reach more than 99 percent and CO when the catalytic combustion reaction is carried out for 1000h at lower reaction temperature₂The selectivity of the catalyst can reach 99 percent, which shows that the catalyst of the invention has higher stability and anti-halogen toxicity capability.

Drawings

FIG. 1 is an XPS spectrum of cobalt in a monolithic catalyst prepared in example 7;

FIG. 2 is an XPS spectrum of cobalt in a monolithic catalyst prepared in example 19;

FIG. 3 is an XPS spectrum of cobalt in the monolithic catalyst prepared in comparative example 5;

figure 4 is an XPS spectrum of cobalt in the monolithic catalyst prepared in comparative example 6.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The inventors of the present invention found, through research, thatIn the type of catalyst, Co in the cobalt oxide³⁺And Co²⁺Under the condition of existing in a specific proportion, the composite oxide containing cobalt oxide and cerium oxide and/or copper oxide and the noble metal active component can generate a synergistic effect, so that the halogen toxicity resistance and stability of the catalyst can be obviously improved, and the catalyst still has excellent catalytic activity and selectivity at a lower reaction temperature in the treatment of waste gas containing bromine-containing organic matters.

In a first aspect, the present invention provides a monolithic catalyst comprising a monolithic support comprising an alumina coating and, supported on said monolithic support, a noble metal active component and a non-noble metal active component;

according to the invention, preferably, said Co³⁺And Co²⁺In a molar ratio of 0.85 to 1.5: 1. in this preferred case, the halogen toxicity resistance, catalytic activity, selectivity and stability of the monolithic catalyst are further improved.

According to the present invention, the amount of the non-noble metal active component supported on an oxide basis is preferably 12 to 110g (for example, 12g, 20g, 30g, 40g, 50g, 60g, 70g, 80g, 90g, 100g, 110g, or any value therebetween), more preferably 50 to 100g, relative to 1L of the monolithic support.

According to the invention, preferably, the molar ratio of Co to Ce in the non-noble metal active component is 2-18: 1 (e.g., can be 2: 1, 4: 1, 6: 1, 8: 1, 10: 1, 12: 1, 14: 1, 16: 1, 18: 1, or any value in between), more preferably 6-14: 1, more preferably 8 to 12: 1.

according to the invention, preferably, the molar ratio of Co to Cu in the non-noble metal active component is 2-12: 1 (e.g., can be 2: 1, 4: 1, 6: 1, 8: 1, 10: 1, 12: 1, or any value in between), more preferably 5-11.5: 1, more preferably 6 to 10: 1.

according to the present invention, the halogen toxicity resistance, catalytic activity, selectivity and stability of the monolithic catalyst are further improved, and preferably, the non-noble metal active component is a composite oxide containing cobalt oxide, cerium oxide and copper oxide.

According to the present invention, the loading amount of the noble metal active component can be selected in a wide range, and preferably, the loading amount of the noble metal active component is 200-.

According to the present invention, preferably, the noble metal is selected from at least one of Au, Ag, Pt, Pd, Ru, Rh, Os, and Ir.

More preferably, the noble metal is Pt and/or Pd.

Further preferably, the noble metals are Pt and Pd.

Further preferably, the molar ratio of Pt and Pd in the noble metal active component is 0.01 to 10: 1, more preferably 0.5 to 5: 1. the Pt and Pd in the optimal proportion are matched, so that the catalytic performance of the catalyst is improved.

According to the present invention, the alumina coating layer is preferably contained in the monolithic support in an amount of 5 to 20% by weight, preferably 6 to 19% by weight, more preferably 7 to 15% by weight. The adoption of the alumina coating with the optimized content can further improve the number of the pore channels and the specific surface area of the monolithic carrier, thereby further improving the catalytic activity and the selectivity of the catalyst.

According to the present invention, the monolith support has a general illustration in the art, and preferably, the monolith support is selected from monolith supports having a parallel channel structure with both ends open.

According to the present invention, the porosity of the monolithic support in cross section can be selected within a wide range, preferably the porosity of the monolithic support in cross section is in the range of 30 to 90%, preferably 45 to 75%. The porosity of the cross section of the monolith support means a ratio of a pore area of the cross section of the monolith support to the entire cross sectional area.

According to the present invention, the cross-sectional area of the channels of the monolithic support can be selected within a wide range, and preferably, the cross-sectional area of each channel is 0.5 to 1.5 μm²More preferably 0.7 to 1.3 μm²。

According to the present invention, the kind of the monolith support may be selected from a wide range, and preferably, the monolith support is a ceramic monolith support.

More preferably, the ceramic monolith carrier is at least one selected from the group consisting of a cordierite monolith carrier, a mullite monolith carrier, a zirconia monolith carrier and an alumina monolith carrier, and further preferably a cordierite monolith carrier and/or a mullite monolith carrier.

In a second aspect, the present invention provides a process for the preparation of a monolithic catalyst, the process comprising:

according to the present invention, preferably, the method further comprises: in the step (1), before the slurry containing the alumina and/or the alumina precursor is coated on the monolithic carrier, the slurry containing the alumina and/or the alumina precursor is stirred and colloid-milled. Preferably, the conditions of the stirring include: the stirring time is 0.1-5h, and the rotation speed is 200-1500 rpm. Preferably, the conditions of the colloid mill include: the colloid mill time is 0.1-5h, and the colloid mill tooth gap size is 0.01-1 mm.

According to the present invention, preferably, the slurry containing alumina and/or an alumina precursor and the monolithic support are used in amounts such that the alumina coating layer content of the monolithic support containing an alumina coating layer obtained in step (1) is 5 to 20 wt%, preferably 6 to 19 wt%, more preferably 7 to 15 wt%.

According to the present invention, preferably, the alumina and/or alumina precursor-containing slurry contains alumina and/or alumina precursor, water, and optionally pore former, and optionally acid.

According to the invention, preferably, the weight ratio of alumina and/or alumina precursor to water, calculated as alumina, is between 0.05 and 0.8: 1, more preferably 0.3 to 0.7: 1.

the slurry may or may not contain a pore-forming agent, and more preferably contains a pore-forming agent. The existence of the pore-forming agent is more beneficial to improving the specific surface area of the alumina coating and improving the catalytic reaction efficiency of the catalyst.

According to the invention, the weight ratio of alumina and/or alumina precursor to pore former, calculated as alumina, is preferably 1: 0.3-2.5, more preferably 1: 0.35-1.5.

The slurry may or may not contain an acid, and more preferably contains an acid. The presence of said acid is more advantageous for optimizing the coating effect of the slurry containing alumina.

According to the present invention, the number of times of coating in step (1) is not particularly limited, and may be one coating or multiple coatings, as long as the required loading amount can be obtained, and the number of times of coating can be specifically selected by those skilled in the art according to actual circumstances.

According to the invention, preferably, the weight ratio of alumina and/or alumina precursor to acid, calculated as alumina, is 1: 0.01 to 0.2, more preferably 1: 0.05-0.15. With this preferred embodiment, the alumina-containing slurry can be made to have a suitable viscosity, further improving the coating effect of the alumina-containing slurry.

According to the present invention, the coating method in the step (1) is not particularly limited as long as the slurry containing alumina can be uniformly adhered to the monolithic support, and is preferably a positive pressure coating method or a negative pressure coating method, and more preferably a negative pressure coating method. The negative pressure coating is performed in a coating machine, and specifically comprises: the alumina-containing slurry at one end of the monolith support is coated onto the monolith support by forming a low pressure environment in a coater. Preferably, the pressure in the coating machine is 0-5 kPa. The negative pressure coating is used in the embodiment of the present invention.

The pressure in the present invention is absolute pressure.

According to the present invention, the kind of the alumina precursor is not particularly limited, and preferably, the alumina precursor is pseudoboehmite and/or alumina sol, more preferably pseudoboehmite.

According to the present invention, there is no particular limitation on the kind of the pore-forming agent as long as it can make the alumina coating layer porous without destroying the entire structure of the alumina coating layer, and preferably, the pore-forming agent is selected from at least one of urea, carboxymethyl cellulose, cetyltrimethyl ammonium bromide, and polyvinyl alcohol, and more preferably, urea.

According to the present invention, there is no particular limitation on the kind of the acid as long as it can increase the viscosity of the alumina-containing slurry, and preferably, the acid is selected from HNO₃、H₂SO₄、HCl、CH₃COOH (acetic acid) and H₂C₂O₄At least one of (oxalic acid), more preferably nitric acid.

According to the present invention, there is no particular limitation on the conditions for the drying in step (1), and preferably, the conditions for the drying in step (1) include: the drying temperature is 80-130 ℃, preferably 100-125 ℃; the drying time is 1-25h, preferably 2-10 h.

More preferably, the drying conditions of step (1) include: heating to the drying temperature from room temperature at the rate of 0.3-0.8 ℃/min for drying.

According to the invention, the method further comprises: before the drying in the step (1), the monolithic carrier coated with the slurry containing the alumina and/or the alumina precursor is purged to remove residual liquid, and then the monolithic carrier is placed at room temperature for 0.5 to 15 hours. The purge may be performed using a wide range of gases, such as air, nitrogen, helium, and other inert gases. The purge is usually performed by a high-pressure purge, and the pressure is not particularly limited as long as the residual liquid can be purged.

According to the present invention, the conditions of the calcination in step (1) are not particularly limited, and preferably, the conditions of the calcination in step (1) include: roasting in an oxygen-containing atmosphere, wherein the roasting temperature is 300-600 ℃, and preferably 450-550 ℃; the roasting time is 3-10h, preferably 5-8 h.

More preferably, the roasting conditions of step (1) include: after drying, heating to the roasting temperature at the speed of 0.3-0.8 ℃/min for roasting.

According to the invention, the oxygen content of the oxygen-containing atmosphere may be selected within a wide range, preferably from 5 to 25% by volume.

According to the present invention, preferably, the oxygen containing atmosphere contains oxygen and optionally an inert gas.

According to the present invention, preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon. It is to be understood that the inert gas according to the present invention refers to a gas that does not participate in the reaction under the firing conditions in the present invention. From an economic point of view, the oxygen-containing atmosphere may be air.

In the step (2) of the present invention, the composite oxide may be loaded on the monolithic carrier with the alumina coating, and then the noble metal active component is loaded, or the noble metal active component may be loaded on the monolithic carrier with the alumina coating, and then the composite oxide is loaded, or the composite oxide and the noble metal active component are loaded on the noble metal active component together. In order to further improve the catalytic performance of the catalyst obtained by the preparation, it is preferable that the step (2) comprises the steps of:

(2-1) loading a composite oxide containing cobalt oxide and cerium oxide and/or copper oxide on an integral carrier containing an alumina coating to obtain a semi-finished catalyst;

(2-2) loading the noble metal active component on the semi-finished product catalyst. With this preferred embodiment, the halogen toxicity resistance, catalytic activity, selectivity and stability of the monolithic catalyst can be further improved.

More preferably, the composite oxide contains cobalt oxide, cerium oxide, and copper oxide.

According to the present invention, preferably, the step (2-1) comprises: coating the slurry containing the composite oxide on an integral carrier containing an alumina coating, and then drying and/or roasting to obtain a semi-finished catalyst; and/or the presence of a gas in the gas,

the step (2-2) comprises: the slurry containing the noble metal source is coated on the semi-finished catalyst and then calcined.

According to the present invention, the manner of coating in step (2-1) is as described above, and will not be described herein.

According to the present invention, the number of times of coating in the step (2-1) is not particularly limited, and may be one coating or multiple coatings, as long as the required loading amount can be obtained, and the number of times of coating can be specifically selected by those skilled in the art according to actual circumstances.

According to the present invention, the solid content of the slurry containing a composite oxide can be selected in a wide range so as to satisfy the coating, and preferably, the solid content of the slurry containing a composite oxide is 10 to 35% by weight, preferably 20 to 30% by weight.

According to the present invention, it is preferred that the slurry containing the composite oxide and the monolithic carrier containing the alumina coating are used in such amounts that the prepared semi-finished catalyst has a composite oxide loading amount of 12 to 110g, more preferably 50 to 100g, in terms of oxide, relative to 1L of the monolithic carrier containing the alumina coating. The halogen toxicity resistance and stability of the monolithic catalyst can be further improved by adopting the preferred loading amount of the composite oxide.

According to the present invention, the drying conditions in the step (2-1) can be selected from a wide range, and preferably, the drying conditions in the step (2-1) include: the drying temperature is 80-130 ℃, and more preferably 100-125 ℃; the drying time is 1-25h, more preferably 2-10 h.

According to the invention, the method further comprises: before the drying in the step (2-1), the monolith type carrier coated with the slurry containing the composite oxide is purged to remove a residual liquid. The purge may be performed using a wide range of gases, such as air, nitrogen, helium, and other inert gases. The purge is usually performed by a high-pressure purge, and the pressure is not particularly limited as long as the residual liquid can be purged.

According to the present invention, the conditions for the calcination in step (2-1) can be selected from a wide range, and preferably, the conditions for the calcination in step (2-1) include: in an oxygen-containing atmosphere, the roasting temperature is 300-600 ℃, and more preferably 450-550 ℃; the calcination time is 3 to 10 hours, more preferably 3.5 to 8 hours.

According to the invention, in the cobalt oxide, the Co³⁺And Co²⁺The selection range of the molar ratio is as described above, and the details are not repeated herein.

According to the present invention, there is no particular limitation on the method for preparing the composite oxide of step (2), and preferably, the composite oxide of step (2) is prepared by a coprecipitation method.

According to the present invention, preferably, the method for preparing the composite oxide of step (2) comprises: mixing a precursor solution containing cobalt and a precursor of cerium and/or a precursor of copper with a precipitator for precipitation reaction to obtain a precipitation product, and then drying and roasting the precipitation product.

According to the present invention, preferably, the method for preparing the composite oxide of step (2) further comprises: before mixing the precursor solution containing cobalt and the precursor solution of cerium and/or copper with the precipitant, colloid milling is performed on the precursor solution containing cobalt and the precursor solution of cerium and/or copper. Preferably, the conditions of the colloid mill include: the colloid mill time is 0.1-5h, and the colloid mill tooth gap size is 0.01-1 mm.

According to the invention, preferably, the cobalt precursor and the cerium precursor and/or the copper precursor are used in such amounts as to obtain a monolithic catalyst having a molar ratio of cobalt to cerium of 2 to 18: 1, more preferably 6 to 14: 1, more preferably 8 to 12: 1.

according to the invention, preferably, the cobalt precursor and the cerium precursor and/or the copper precursor are used in such amounts as to obtain a monolithic catalyst having a molar ratio of cobalt to copper, calculated as the metal element, of 2 to 12: 1, more preferably 5 to 11.5: 1, more preferably 6 to 10: 1.

more preferably, the precursor solution contains a precursor of cobalt, a precursor of cerium, and a precursor of copper. The catalytic performance of the catalyst can be further improved with this preferred embodiment.

According to the present invention, there is no particular limitation on the kinds of the cobalt precursor, the cerium precursor, and the copper precursor as long as free cobalt ions, cerium ions, and copper ions can be provided, and preferably, the cobalt precursor, the cerium precursor, and the copper precursor are each independently selected from at least one of metal nitrates, acetates, sulfates, oxalates, and halides, and more preferably, nitrates.

According to the present invention, the kind of the precipitant is not particularly limited as long as it can react with cobalt ions, cerium ions and copper ions to generate precipitates, and preferably, the precipitant is selected from at least one of carbonates, bicarbonates and hydroxides of alkali metals, more preferably at least one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and lithium hydroxide, and more preferably sodium carbonate and/or sodium hydroxide.

According to the present invention, in a preferred embodiment, the conditions of the precipitation reaction include: the reaction temperature is 50-85 ℃ (for example, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, or any value between any two values), more preferably 55-80 ℃; the pH is 8.5 to 11 (e.g., can be 8.5, 9, 9.5, 10, 10.5, 11, 11.5, or any value in between), and more preferably is 9 to 10.

According to the invention, preferably, stirring can also be carried out during the precipitation reaction. The stirring is advantageous for improving the effect of the precipitation reaction. The stirring rate can be selected within a wide range, and preferably, the stirring rate is 200-1500 rpm.

According to the present invention, the conditions for drying the precipitated product are not particularly limited, and preferably, the drying conditions include: the drying temperature is 100-120 ℃, and the drying time is 2-8 h.

According to the present invention, the conditions for calcining the precipitated product are not particularly limited, and preferably, the calcining conditions include: in an oxygen-containing atmosphere, the roasting temperature is 400-600 ℃, and more preferably 450-550 ℃; the calcination time is 3 to 8 hours, more preferably 3.5 to 7 hours.

According to the present invention, there is no particular limitation on the method of coating in step (2-2), and preferably, the method of coating is selected from a water coating method, a dipping method or a spraying method, more preferably a dipping method.

According to the present invention, it is preferable that the method of coating the slurry containing the noble metal source on the semi-finished catalyst in the step (2-2) employs an equivalent impregnation method. The preferred equivalent impregnation method is more advantageous in increasing the coating effect and reducing the loss of precious metals.

According to the present invention, the content of the noble metal in the noble metal source-containing slurry is not particularly limited, and preferably, the noble metal content of the noble metal source-containing slurry is 0.05 to 0.5% by weight, preferably 0.1 to 0.35% by weight, in terms of the metal element.

According to the present invention, the amounts of the slurry containing a noble metal source and the semi-finished catalyst can be selected within a wide range, and preferably, the amounts of the slurry containing a noble metal source and the semi-finished catalyst are such that the supported amount of the noble metal in the obtained monolithic catalyst is 200-2000mg, more preferably 400-1500mg, in terms of the metal element, relative to 1L of the monolithic support containing an alumina coating.

According to the present invention, preferably, the noble metal source is selected from a precursor of at least one of Au, Ag, Pt, Pd, Ru, Rh, Os, and Ir, more preferably a precursor of Pt and/or a precursor of Pd, and further preferably a precursor of Pt and a precursor of Pd.

According to the invention, the amount of the precursor of Pt and the precursor of Pd can be selected in a wide range, and preferably, the amount of the precursor of Pt and the precursor of Pd is such that the molar ratio of Pt and Pd supported on the surface of the alumina-coating-containing monolithic support is 0.01 to 10: 1, more preferably 0.05 to 5: 1.

according to the present invention, there is no particular limitation on the kinds of the precursor of Pt and the precursor of Pd, and preferably, the precursor of Pt and the precursor of Pd are each independently a soluble acid and/or a soluble salt of a metal.

More preferably, the precursor of Pt is selected from at least one of chloroplatinic acid, platinum nitrate and platinum chloride, and further preferably chloroplatinic acid.

More preferably, the precursor of Pd is at least one selected from palladium nitrate, tetraaminopalladium nitrate and palladium chloride, and still more preferably palladium chloride.

According to the present invention, the conditions for the calcination in step (2-2) can be selected from a wide range, and preferably, the conditions for the calcination in step (2-2) include: in an oxygen-containing atmosphere, the roasting temperature is 300-600 ℃, and more preferably 450-550 ℃; the calcination time is 3-10h, more preferably 4-8 h.

According to the present invention, preferably, the method further comprises: in the step (2-2), the slurry containing the noble metal source is coated on the semi-finished catalyst before calcination, and then dried. The drying conditions can be selected within a wide range, and preferably include: the drying temperature is 80-130 ℃, and more preferably 100-125 ℃; the drying time is 1-25h, more preferably 3.5-7 h.

According to the invention, the oxygen content of the oxygen-containing atmosphere may be selected within a wide range, preferably from 5 to 20 vol%.

According to the present invention, preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon. It is to be understood that the inert gas according to the present invention refers to a gas that does not participate in the reaction under the firing conditions in the present invention.

In a third aspect, the present invention provides a monolithic catalyst prepared by the preparation method of the second aspect. The monolithic catalyst has high halogen toxicity resistance, and still has high catalytic activity and selectivity at low reaction temperature. The structural composition and the component content of the monolithic catalyst are as described in the first aspect, and will not be described herein again.

In a fourth aspect, the present invention provides a method for purifying an exhaust gas containing a bromine-containing organic substance, wherein the exhaust gas containing a bromine-containing organic substance is subjected to catalytic combustion in an oxygen-containing atmosphere by contacting with the monolithic catalyst of the first or third aspect.

Specifically, in the presence of an oxygen-containing atmosphere, waste gas containing bromine-containing organic matters is contacted with a catalyst to be catalytically combusted to generate carbon dioxide and water, and if the waste gas also comprises the bromine-containing organic matters, hydrogen bromide and/or bromine are also generated.

According to the present invention, in order to further enhance the effect of purifying the exhaust gas containing the bromine-containing organic matter, it is preferable that the catalytic combustion conditions include: the temperature is 200-450 ℃, and the optimal temperature is 250-400 ℃; the volume space velocity is 3000-30000h^-1Preferably 5000-^-1(ii) a The pressure is 0 to 3MPa, preferably 0 to 2 MPa.

In the present invention, the waste gas containing organic bromine compounds may be any industrial waste gas that can be treated by a catalytic combustion method. The invention has wider selection range for the composition of the waste gas containing the bromine-containing organic matters and the content of the bromine-containing organic matters. In the research process, the inventor of the invention finds that the catalyst provided by the invention is particularly suitable for treating the waste gas containing the bromine-containing organic matters.

According to a preferred embodiment of the present invention, the content of the bromine-containing organic substance in the exhaust gas containing the bromine-containing organic substance is 0.1 to 150ppm, more preferably 0.1 to 100ppm, in terms of Br element.

According to a preferred embodiment of the present invention, the bromine-containing organic substance includes, but is not limited to, at least one of monobromomethane, dibromomethane, monobromoethane, dibromoethane, monobromoethylene and dibromoethylene.

According to the present invention, preferably, the exhaust gas containing bromine-containing organic compounds further includes ester compounds and/or aromatic hydrocarbons. The ester compounds include but are not limited to methyl acetate, ethyl acetate, preferably methyl acetate; the aromatic hydrocarbon includes, but is not limited to, at least one of benzene, toluene, xylene, ethylbenzene, diethylbenzene, n-propylbenzene, and isopropylbenzene.

In the examples of the present invention, methyl acetate, p-xylene, and dibromomethane are exemplified as the off-gas containing the bromine-containing organic matter, and the present invention is not limited thereto.

According to the present invention, the content of oxygen in the oxygen-containing atmosphere may be selected from a wide range as long as it is capable of reacting the exhaust gas containing bromine-containing organic compounds, and in order to further enhance the purification effect, it is preferable that the content of oxygen in the oxygen-containing atmosphere is 3 to 100% by volume.

According to the present invention, preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon. It is to be understood that the inert gas according to the present invention refers to a gas that does not participate in the reaction under the reaction conditions in the present invention.

It will be appreciated by those skilled in the art that the monolithic catalyst may be subjected to a reduction before the catalytic reaction, and the reduction method is not particularly limited and may be a reduction method conventionally used in the art, for example, the reduction method includes: reducing the catalyst for 3-10h at the temperature of 250-350 ℃ in a mixed atmosphere of hydrogen and inert gas. Preferably, the content of hydrogen in the mixed gas of hydrogen and inert gas is 1 to 10% by volume. Preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon. It is to be understood that the inert gas according to the present invention refers to a gas that does not participate in the reaction under the reducing conditions in the present invention.

The present invention will be described in detail below by way of examples. In the following examples of the present invention,

Co³⁺and Co²+ molar ratio was determined by XPS analysis;

methyl acetate conversion rate ÷ (amount of unreacted methyl acetate + amount of reacted methyl acetate species) amount of reacted methyl acetate species;

para-xylene conversion ÷ (amount of unreacted para-xylene plus amount of reacted para-xylene);

dibromomethane conversion ═ amount of reacted dibromomethane species ÷ (amount of unreacted dibromomethane species + amount of reacted dibromomethane species);

CO₂selectivity of (a) the amount of substance of the reactant converted to carbon dioxide ÷ (amount of substance of the reactant converted to non-carbon dioxide + amount of substance of the reactant converted to carbon dioxide);

the pseudoboehmite is a commercial product of Jiangsu three-agent industry Co Ltd, and the content of the alumina is 72 percent by weight;

the firing described in the following examples and comparative examples is carried out in an air atmosphere without particular limitation.

Example 1

(1) Mixing 150g of pseudo-boehmite calculated by alumina, 75g of urea and 15g of concentrated nitric acid (mass fraction is 68%), and 300g of water, stirring for 30 minutes at the rotating speed of 500rpm, and then carrying out colloid milling for 30 minutes by using a colloid mill (the width of a tooth gap of the colloid mill is 0.05mm) to obtain slurry containing alumina;

in a coater, a slurry containing alumina was coated on a cordierite monolith carrier (having a parallel channel structure with openings at both ends, a porosity of 60%, and a cross-sectional area of each channel of 1 mm) under a condition of 3kPa²) And after coating, blowing residual liquid in the integral carrier by adopting high-pressure nitrogen, standing at room temperature for 10h, raising the temperature from 20 ℃ to 110 ℃ at the heating rate of 0.5 ℃/min, keeping for 10h, drying, raising the temperature from 110 ℃ to 550 ℃ at the temperature of 0.5 ℃/min, keeping for 6h, roasting to obtain the integral carrier containing the alumina coating, and carrying out multiple times of dipping, drying and roasting to obtain the integral carrier containing the alumina coating, wherein the alumina coating accounts for 10% of the total mass of the alumina coating and the integral carrier.

(2) Preparing cobalt nitrate hexahydrate and cerium nitrate hexahydrate into aqueous solution according to a molar ratio shown in table 1, adding sodium carbonate solution into the aqueous solution under the condition of stirring at 60 ℃ until the pH value is 9.5, filtering, drying the obtained precipitate at 110 ℃ for 5 hours, and roasting at 500 ℃ for 6 hours to obtain composite oxide particles containing cobalt oxide and cerium oxide;

dispersing the obtained composite oxide particles into water, then carrying out colloid milling for 30min by using a colloid mill (the tooth peak size of the colloid mill is 0.05mm), so as to prepare slurry containing the composite oxide, wherein the solid content of the slurry is 25 wt%, coating the slurry containing the composite oxide on an integral carrier containing an alumina coating in a coating machine under the condition of 3kPa, blowing the residual slurry in a pore channel by using high-pressure nitrogen after the coating is finished, then drying for 5h at 110 ℃, roasting for 6h at 550 ℃, and carrying out multiple times of impregnation, drying and roasting so as to obtain a semi-finished catalyst, wherein the loading capacity of the composite oxide is 80g/L in terms of oxide relative to 1L of the integral carrier containing the alumina coating.

Preparing chloroplatinic acid and palladium chloride into aqueous solution containing platinum element and palladium element (the mass fraction of noble metal platinum and palladium is 0.1 wt%), impregnating the semi-finished catalyst with the aqueous solution containing platinum element and palladium element, drying at 110 ℃ for 5h, and calcining at 550 ℃ for 6h to obtain the monolithic catalyst, wherein the loading amounts of platinum and palladium are calculated by metal element relative to 1L of monolithic carrier containing an alumina coatingAt 400mg/L, the molar ratio of the platinum element to the palladium element in the obtained monolithic carrier was 0.25: 1. co in the obtained monolithic support³⁺And Co²⁺The molar ratio of (A) is shown in Table 1.

(3) Reducing the monolithic catalyst obtained in the step (2), specifically: the catalyst was subjected to reduction treatment at 300 ℃ for 6 hours in a mixed atmosphere of hydrogen and nitrogen (containing 5% by volume of hydrogen). In the mixed atmosphere of oxygen and nitrogen (oxygen content is 10 vol%), under the pressure of 0.1MPa and the volume space velocity of 20000h^-1Under the conditions of (1) catalytic combustion of a bromine-containing organic matter-containing exhaust gas containing 1000ppm of methyl acetate, 500ppm of p-xylene and 100ppm of dibromomethane in contact with a reduced monolithic catalyst, gradually raising the reaction temperature at a rate of 0.1 ℃/min from 200 ℃, recording the lowest reaction temperature T1 at 99% conversion of methyl acetate, the lowest reaction temperature T2 at 99% conversion of p-xylene and the lowest reaction temperature T3 at 99% conversion of dibromomethane, respectively, and calculating the CO conversion at 20h₂Selectivity of (2).

(4) Under the conditions of T3 temperature and other constant catalytic combustion conditions, the catalytic combustion reaction is carried out, and the conversion rate of methyl acetate, p-xylene and dibromomethane and the CO are reached to the 1000h₂The selectivities are shown in Table 2.

Examples 2 to 3

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by the method of example 1, except that cobalt nitrate hexahydrate and cerium nitrate hexahydrate were prepared as an aqueous solution in the molar ratio shown in table 1.

Content of each component of the obtained monolithic catalyst, Co³⁺And Co²⁺The molar ratio of (A) is shown in Table 1; t1, T2 and T3 and CO₂The selectivities are shown in Table 2.

The conversion rate of methyl acetate, p-xylene and dibromomethane and CO are calculated by the running time of 1000h₂The selectivities are shown in Table 2.

Examples 4 to 6

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by catalyzing the exhaust gas in the same manner as in example 1, except that cerium nitrate hexahydrate was replaced with copper nitrate hexahydrate, and cobalt nitrate hexahydrate and copper nitrate hexahydrate were prepared as an aqueous solution in the molar ratio shown in table 1.

Example 7

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by catalyzing the exhaust gas in the same manner as in example 1, except that cobalt nitrate hexahydrate and cerium nitrate hexahydrate were replaced with cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate, and the cobalt nitrate hexahydrate, the cerium nitrate hexahydrate and the copper nitrate hexahydrate were prepared as an aqueous solution in the molar ratio shown in table 1. The XPS spectrum of Co in the resulting monolithic catalyst is shown in FIG. 1.

Example 8

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in accordance with the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 60 ℃ to adjust the pH to 8.5.

The conversion rate of methyl acetate, p-xylene and dibromomethane is up to 1000hAnd CO₂The selectivities are shown in Table 2.

Example 9

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in accordance with the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 60 ℃ to adjust the pH to 9.

Example 10

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 60 ℃ to adjust the pH to 10.

Example 11

A monolithic catalyst was prepared and reacted with an exhaust gas containing bromine-containing organic compound by the method of example 7, except that the alumina coating layer was 19% by mass of the total mass of the alumina coating layer and the monolithic carrier.

When the reaction is carried out for 1000h, methyl acetate, p-xylene and dibromoConversion of methane and CO₂The selectivities are shown in Table 2.

Example 12

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that the supported amount of the composite oxide was 105g/L in terms of oxide with respect to 1L of the monolithic support containing an alumina coating layer.

Example 13

A monolithic catalyst was prepared and reacted with the exhaust gas containing a bromine-containing organic compound by the method of example 7, except that the molar ratio of platinum element to palladium element in the obtained monolithic catalyst was 0.1: 1.

Example 14

A monolithic catalyst was prepared and reacted with the exhaust gas containing a bromine-containing organic compound by the method of example 7, except that the molar ratio of platinum element to palladium element in the obtained monolithic catalyst was 0.5: 1.

Example 15

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that the supported amounts of platinum and palladium were 800mg/L in terms of metal elements with respect to 1L of the monolithic support containing an alumina coating layer.

Example 16

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that the supported amounts of platinum and palladium were 1500mg/L in terms of metal elements with respect to 1L of the monolithic support containing an alumina coating layer.

Example 17

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by the method of example 7, except that in the step (3), an exhaust gas containing a bromine-containing organic compound, which contained 2000ppm of methyl acetate, 700ppm of p-xylene and 200ppm of dibromomethane, was contacted with the monolithic catalyst obtained in the step (2) to react.

Example 18

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by the method of example 7, except that in the step (3), an exhaust gas containing a bromine-containing organic compound, which contained 3000ppm of methyl acetate, 1000ppm of p-xylene and 300ppm of dibromomethane, was contacted with the monolithic catalyst obtained in the step (2) to carry out the reaction.

Example 19

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 70 ℃ to adjust the pH to 9.5. The XPS spectrum of Co in the resulting monolithic catalyst is shown in FIG. 2.

Example 20

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 60 ℃ to adjust the pH to 8.

When the reaction is carried out for 1000h, acetic acid is addedConversion of methyl ester, p-xylene and dibromomethane and CO₂The selectivities are shown in Table 2.

Example 21

A monolithic catalyst was prepared and reacted with the exhaust gas containing a bromine-containing organic compound by the method of example 7, except that the molar ratio of platinum element to palladium element in the obtained monolithic carrier was 10: 1.

Example 22

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that the non-noble metal active component was supported at a supporting amount of 50g in terms of oxide with respect to 1L of the monolithic support.

Comparative example 1

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that the alumina-coated monolithic carrier obtained in step (1) was impregnated with an aqueous solution containing a platinum element and a palladium element without supporting a composite oxide in step (2).

The contents of the components of the obtained monolithic catalyst are shown in Table 1; t1, T2 and T3 and CO₂The selectivities are shown in Table 2.

Comparative example 2

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by catalyzing the exhaust gas in the same manner as in example 7, except that cerium nitrate hexahydrate and copper nitrate hexahydrate were replaced with cobalt nitrate hexahydrate, and the cobalt nitrate hexahydrate was made into an aqueous solution, in terms of metal elements.

Comparative example 3

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by catalyzing the exhaust gas in the same manner as in example 7, except that cobalt nitrate hexahydrate and copper nitrate hexahydrate were replaced with cerium nitrate hexahydrate, and the cerium nitrate hexahydrate was prepared as an aqueous solution, in terms of metal elements.

Comparative example 4

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound by catalyzing the exhaust gas in the same manner as in example 7, except that cobalt nitrate hexahydrate and cerium nitrate hexahydrate were replaced with copper nitrate hexahydrate, and the copper nitrate hexahydrate was prepared as an aqueous solution in terms of metal elements.

Comparative example 5

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 20 ℃ to adjust the pH to 9.5. The XPS spectrum of Co in the resulting monolithic catalyst is shown in FIG. 3.

Comparative example 6

A monolithic catalyst was prepared and reacted with an exhaust gas containing a bromine-containing organic compound in the same manner as in example 7, except that cobalt nitrate hexahydrate, cerium nitrate hexahydrate and copper nitrate hexahydrate were prepared in the form of an aqueous solution in the molar ratio shown in Table 1, and a sodium carbonate solution was added thereto with stirring at 40 ℃ to adjust the pH to 9.5. The XPS spectrum of Co in the resulting monolithic catalyst is shown in FIG. 4.

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the monolithic catalyst prepared by the embodiment of the technical scheme of the invention can still obtain the effect that the conversion rates of methyl acetate, p-xylene and dibromomethane reach more than 99% at a lower reaction temperature, and CO is reacted for 20h₂The selectivity of the monolithic catalyst can reach 99 percent, which shows that the monolithic catalyst has higher catalytic activity and selectivity, and the conversion rates of methyl acetate, p-xylene and dibromomethane can reach more than 99 percent when the catalytic combustion reaction is carried out for 1000 hours at the temperature of T3, and CO₂The selectivity of the catalyst can reach 99 percent, which shows that the catalyst of the invention has higher stability and anti-halogen toxicity capability.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A monolithic catalyst comprising a monolithic support comprising an alumina coating and a noble metal active component and a non-noble metal active component supported on said monolithic support;

2. according to claim 1The catalyst of (1), wherein the Co³⁺And Co²⁺In a molar ratio of 0.85 to 1.5: 1;

preferably, the loading amount of the non-noble metal active component is 12-110g, more preferably 50-100g, calculated by oxide, relative to 1L of the monolithic carrier;

preferably, the molar ratio of Co to Ce in the non-noble metal active component is 2-18: 1, more preferably 6 to 14: 1, more preferably 8 to 12: 1;

preferably, the molar ratio of Co to Cu in the non-noble metal active component is 2-12: 1, more preferably 5 to 11.5: 1, more preferably 6 to 10: 1;

preferably, the non-noble metal active component is a composite oxide containing cobalt oxide, cerium oxide and copper oxide.

3. The catalyst according to claim 1 or 2, wherein the loading amount of the noble metal active component is 200-2000mg, more preferably 400-1500mg, in terms of metal element, relative to 1L of the monolithic support;

preferably, the noble metal is selected from at least one of Au, Ag, Pt, Pd, Ru, Rh, Os, and Ir;

preferably, the noble metal is Pt and/or Pd;

preferably, the noble metals are Pt and Pd;

further preferably, the molar ratio of Pt and Pd in the noble metal active component is 0.01 to 10: 1, more preferably 0.05 to 5: 1.

4. a catalyst according to any one of claims 1 to 3, wherein the alumina coating is present in the monolithic support in an amount of from 5 to 20 wt%, preferably from 6 to 19 wt%, more preferably from 7 to 15 wt%.

5. The catalyst according to any one of claims 1 to 4, wherein the porosity of the cross section of the monolithic support is 30 to 90%;

preferably, the monolithic carrier is a ceramic monolithic carrier;

preferably, the ceramic monolith support is selected from at least one of a cordierite monolith support, a mullite monolith support, a zirconia monolith support and an alumina monolith support.

6. A process for preparing a monolithic catalyst, comprising:

7. the production method according to claim 6, wherein the slurry containing alumina and/or an alumina precursor and the monolithic support are used in amounts such that the alumina coating layer is contained in the alumina coating layer-containing monolithic support obtained in step (1) in an amount of 5 to 20% by weight, preferably 6 to 19% by weight, more preferably 7 to 15% by weight;

preferably, the slurry containing alumina and/or alumina precursors contains alumina and/or alumina precursors, water and optionally pore formers, optionally acids;

preferably, the weight ratio of alumina and/or alumina precursor to water, calculated as alumina, is between 0.05 and 0.8: 1, more preferably 0.3 to 0.7: 1;

preferably, the weight ratio of the alumina and/or the alumina precursor to the pore former, calculated as alumina, is 1: 0.3-2.5, more preferably 1: 0.35-1.5;

preferably, the weight ratio of alumina and/or alumina precursor to acid, calculated as alumina, is 1: 0.01 to 0.2, more preferably 1: 0.05-0.15;

preferably, the alumina precursor is pseudo-boehmite and/or alumina sol;

preferably, the pore-forming agent is selected from at least one of urea, carboxymethyl cellulose, cetyl trimethyl ammonium bromide and polyvinyl alcohol;

preferably, the acid is selected from HNO₃、H₂SO₄、HCl、CH₃COOH and H₂C₂O₄At least one of;

preferably, the drying conditions of step (1) include: the drying temperature is 80-130 ℃, preferably 100-125 ℃; the drying time is 1-25h, preferably 2-10 h;

preferably, the roasting conditions in step (1) include: roasting in an oxygen-containing atmosphere, wherein the roasting temperature is 300-600 ℃, and preferably 450-550 ℃; the roasting time is 3-10h, preferably 5-8 h.

8. The production method according to claim 6 or 7, wherein the step (2) comprises the steps of:

(2-2) loading a noble metal active component on the semi-finished product catalyst;

preferably, the composite oxide contains cobalt oxide, cerium oxide and copper oxide.

9. The production method according to claim 8, wherein the step (2-1) includes: coating the slurry containing the composite oxide on an integral carrier containing an alumina coating, and then drying and/or roasting to obtain a semi-finished catalyst; and/or the presence of a gas in the gas,

the step (2-2) comprises: coating the slurry containing the noble metal source on the semi-finished catalyst, and then roasting;

preferably, the solid content of the slurry containing the composite oxide is 10 to 35% by weight, preferably 20 to 30% by weight;

preferably, the slurry containing the composite oxide and the monolithic carrier containing the alumina coating are used in such amounts that the prepared semi-finished catalyst has a composite oxide loading amount of 12 to 110g, more preferably 50 to 100g, in terms of oxide, relative to 1L of the monolithic carrier containing the alumina coating;

preferably, the drying conditions of step (2-1) include: the drying temperature is 80-130 ℃, and more preferably 100-125 ℃; the drying time is 1-25h, more preferably 2-10 h;

preferably, the roasting conditions in step (2-1) include: in an oxygen-containing atmosphere, the roasting temperature is 300-600 ℃, and more preferably 450-550 ℃; the calcination time is 3 to 10 hours, more preferably 3.5 to 8 hours.

10. The production method according to any one of claims 6 to 9, wherein, in the cobalt oxide, the Co is present in the cobalt oxide³⁺And Co²⁺In a molar ratio of 0.85 to 1.5: 1;

preferably, the composite oxide in the step (2) is prepared by a coprecipitation method;

preferably, the preparation method of the composite oxide in the step (2) comprises: mixing a precursor solution containing cobalt and a precursor of cerium and/or a precursor of copper with a precipitator for precipitation reaction to obtain a precipitation product, and then drying and roasting the precipitation product;

preferably, the precursors of cobalt and cerium and/or the precursors of copper are used in such amounts as to obtain a monolithic catalyst in which the molar ratio of cobalt to cerium, calculated as the metal element, is between 2 and 18: 1, more preferably 6 to 14: 1, more preferably 8 to 12: 1; cobalt to copper molar ratio 2-12: 1, more preferably 5 to 11.5: 1, more preferably 6 to 10: 1;

preferably, the precursor solution contains a precursor of cobalt, a precursor of cerium and a precursor of copper;

preferably, the precursor of cobalt, the precursor of cerium and the precursor of copper are each independently selected from at least one of nitrate, acetate, sulfate, oxalate and halide of metal;

preferably, the precipitant is at least one of carbonate, bicarbonate and hydroxide of alkali metal, more preferably at least one selected from the group consisting of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide and lithium hydroxide;

preferably, the conditions of the precipitation reaction include: the reaction temperature is 50-85 ℃, and more preferably 55-80 ℃; the pH value is 8.5-11, and more preferably 9-10;

preferably, the conditions for drying the precipitated product include: the drying temperature is 100-120 ℃, and the drying time is 2-8 h;

preferably, the conditions for calcining the precipitated product include: in an oxygen-containing atmosphere, the roasting temperature is 400-600 ℃, and more preferably 450-550 ℃; the calcination time is 3 to 8 hours, more preferably 3.5 to 7 hours.

11. The production method according to claim 9, wherein the slurry containing a noble metal source and the semi-finished catalyst are used in amounts such that the supported amount of the noble metal in the obtained monolithic catalyst is 200-2000mg, more preferably 400-1500mg, in terms of the metal element, relative to 1L of the monolithic support containing an alumina coating;

preferably, the noble metal source is selected from at least one precursor of Au, Ag, Pt, Pd, Ru, Rh, Os and Ir, more preferably a precursor of Pt and/or a precursor of Pd, and further preferably a precursor of Pt and a precursor of Pd;

preferably, the precursor of Pt and the precursor of Pd are used in such amounts that the molar ratio of Pt to Pd supported on the surface of the alumina-coated monolithic carrier is 0.01-10: 1, more preferably 0.05 to 5: 1;

preferably, the precursor of Pt and the precursor of Pd are each independently an acid and/or a salt of a metal;

preferably, the precursor of Pt is selected from at least one of chloroplatinic acid, platinum nitrate and platinum chloride;

preferably, the precursor of Pd is selected from at least one of palladium nitrate, tetraaminopalladium nitrate and palladium chloride.

12. A monolithic catalyst prepared by the process of any one of claims 6 to 11.

13. A method for purifying an exhaust gas containing a bromine-containing organic substance, characterized in that the exhaust gas containing a bromine-containing organic substance is subjected to catalytic combustion in an oxygen-containing atmosphere by contacting it with the monolithic catalyst according to any one of claims 1 to 5 and claim 12.

14. The method of claim 13, wherein the conditions of catalytic combustion comprise: the temperature is 200-450 ℃, and the optimal temperature is 250-400 ℃; the volume space velocity is 3000-30000h^-1Preferably 5000-^-1(ii) a The pressure is 0 to 3MPa, preferably 0 to 2 MPa.

15. The method according to claim 13 or 14, wherein the content of the bromine-containing organic matter in the off-gas containing the bromine-containing organic matter is 0.1 to 100ppm as Br element;

preferably, the oxygen-containing atmosphere contains oxygen and optionally an inert gas;

preferably, the oxygen content of the oxygen-containing atmosphere is 3 to 100% by volume;

preferably, the inert gas is selected from at least one of nitrogen, helium, neon and argon.