CN116116210B

CN116116210B - Method for collaboratively removing nitrogen oxides, mercury and dioxins, catalyst and method for preparing catalyst

Info

Publication number: CN116116210B
Application number: CN202310198801.2A
Authority: CN
Inventors: 陈建军; 史建强; 李俊华
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2023-03-03
Filing date: 2023-03-03
Publication date: 2024-11-12
Anticipated expiration: 2043-03-03
Also published as: CN116116210A

Abstract

The invention provides a method for cooperatively removing nitrogen oxides, mercury and dioxin, a catalyst and a preparation method of the catalyst. The method for cooperatively removing nitrogen oxides, mercury and dioxin comprises the following steps: a step of removing nitrogen oxides using a first catalyst; and a step of removing dioxin and mercury by using a second catalyst. The method for removing the nitrogen oxides, the mercury and the dioxin is simple and feasible, convenient to operate, has wide application prospect and is suitable for industrial batch production.

Description

Method for cooperatively removing nitrogen oxides, mercury and dioxin, catalyst and preparation method of catalyst

Technical Field

The invention relates to a method for removing nitrogen oxides, mercury and dioxin, a catalyst and a preparation method of the catalyst, and belongs to the fields of environmental protection and waste gas purification.

Background

With the rapid development of modern industry, a great amount of industrial waste gas causes more and more serious air pollution, and has become one of the most concerned problems. Nitrogen oxides (NO _x) are important primary contaminants that initiate haze and near-surface ozone. Dioxin (dioxin) is a durable and highly toxic substance that can directly and severely harm human bodies and other organisms. Mercury (Hg ⁰) has high toxicity and bioaccumulation, and causes various harmful effects on human health and biological systems. And NO _x, dioxan and Hg ⁰ coexist in the flue gas of the industrial processes such as cement production, metal smelting, garbage incineration, steel sintering and the like. In order to solve the pollution problem, the emission standard of relevant industrial flue gas is gradually increased all over the world.

Ammonia selective catalytic reduction (NH ₃ -SCR) denitration technology is one of the most widely used technologies in industry at present, and SCR core technology is a commercial vanadium-based catalyst which can effectively control the emission of NO _x. Meanwhile, a great deal of research shows that the vanadium-based SCR catalyst can indeed promote the oxidation of Hg ⁰ and can also realize the oxidation of Volatile Organic Compounds (VOCs), so that the control of multiple pollutants such as NO _x、Hg⁰, VOCs and the like by utilizing the SCR catalyst is possible, but the process needs to spray hydrogen chloride (HCl) and can cause the corrosion of equipment. Meanwhile, in practical application, the phenomenon that the content of dioxin is not reduced and increased after the flue gas passes through the vanadium-tungsten-titanium catalyst is found, so that the tungsten-titanium catalyst also becomes a manufacturer of dioxin.

Therefore, the catalyst is used for effectively controlling the emission of multi-pollutants such as NO _x、Hg⁰, VOCs and the like under the condition of NO HCl, and has great theoretical, economic and practical significance for developing a multi-pollution control technology with development prospect.

Disclosure of Invention

Problems to be solved by the invention

In view of the technical problems in the prior art, the invention firstly provides a method for removing nitrogen oxides, mercury and dioxin, and the method is simple and feasible, is convenient to operate and has wide application prospect.

Further, the invention also provides a catalyst for removing nitrogen oxides, mercury and dioxin, which has excellent catalytic effect, excellent NH ₃ selective reduction NO activity, hg ⁰ oxidation efficiency, dioxin (chlorobenzene) conversion rate and stable sulfur and water resistance.

Furthermore, the invention also provides a preparation method of the catalyst, which is simple and easy to implement, raw materials are easy to obtain, and the preparation method is suitable for industrial batch production.

Solution for solving the problem

The invention provides a method for cooperatively removing nitrogen oxides, mercury and dioxin, which comprises the following steps:

a step of removing nitrogen oxides using a first catalyst;

And a step of removing dioxin and mercury by using a second catalyst.

The method according to the present invention, wherein the first catalyst comprises a first carrier and a first active ingredient, the content of the first carrier being 80-99% based on 100% of the total mass of the first catalyst; the content of the first active ingredient is 1-15%.

The method of the present invention, wherein the first support comprises one or a combination of two or more of titanium oxide, aluminum oxide, cerium oxide, zirconium oxide, tin oxide, and silicon oxide; and/or

The first active ingredient comprises one or more than two of vanadium oxide, iron oxide, copper oxide, tungsten oxide, molybdenum oxide and manganese oxide.

The method according to the present invention, wherein the content of the titanium oxide in the first carrier is 75% to 90%, the content of the aluminum oxide is 0% to 5%, the content of the cerium oxide is 1% to 10%, the content of the zirconium oxide is 0% to 5%, the content of the tin oxide is 1% to 10%, and the content of the silicon oxide is 0% to 5%, based on 100% of the total mass of the first catalyst; and/or

The content of the vanadium oxide in the first active component is 1% -3%, the content of the iron oxide is 0% -5%, the content of the copper oxide is 0% -1%, the content of the tungsten oxide is 0% -5%, the content of the molybdenum oxide is 1% -5%, and the content of the manganese oxide is 1% -5% based on 100% of the total mass of the first catalyst.

The method according to the invention, wherein the first catalyst further has sulfate ions therein; the content of sulfate ions is 1.5-3% calculated by SO ₃ and calculated by 100% of the total mass of the first catalyst; and/or

The first catalyst also has phosphate ions therein, wherein the content of the phosphate ions is 5% or less in terms of P ₂O₅, based on 100% of the total mass of the first catalyst.

The method according to the present invention, wherein the second catalyst comprises a second carrier and a second active ingredient, the content of the second carrier being 80-99% based on 100% of the total mass of the second catalyst; the content of the second active ingredient is 1-15%.

The method of the present invention, wherein the second support comprises one or a combination of two or more of titanium oxide, aluminum oxide, cerium oxide, zirconium oxide, tin oxide, and silicon oxide; and/or

The second active ingredient comprises one or more of ruthenium oxide, platinum oxide, cobalt oxide, gold oxide, vanadium oxide, iron oxide, copper oxide, molybdenum oxide and manganese oxide.

The method according to the present invention, wherein the content of the titanium oxide in the second carrier is 70% to 90%, the content of the aluminum oxide is 0% to 5%, the content of the cerium oxide is 1% to 10%, the content of the zirconium oxide is 0% to 5%, the content of the tin oxide is 1% to 10%, and the content of the silicon oxide is 0% to 5%, based on 100% of the total mass of the second catalyst; and/or

In the second active component, the content of ruthenium oxide is 0.1% -1%, the content of platinum oxide is 0% -1%, the content of cobalt oxide is 1% -20%, the content of gold oxide is 0% -1%, the content of vanadium oxide is 0% -5%, the content of iron oxide is 0% -1%, the content of copper oxide is 0% -5%, the content of molybdenum oxide is 0% -5%, and the content of manganese oxide is 0% -10%, based on 100% of the total mass of the second catalyst.

The method according to the present invention, wherein the second catalyst further has phosphate ions therein, and the content of phosphate ions is 5% or less in terms of P ₂O₅, based on 100% by mass of the total mass of the second catalyst.

The invention also provides a catalyst comprising a first catalyst according to the invention.

The invention also provides a preparation method of the first catalyst, which comprises the following steps:

dissolving a precursor of a first carrier in a solvent to obtain a first carrier precursor solution;

mixing the first carrier precursor solution with an alkaline precipitant and drying to obtain a first carrier dried product;

calcining the first carrier dried product to obtain a first carrier;

Dissolving a precursor of a first active ingredient and a cosolvent in a solvent to obtain a precursor solution of the first active ingredient;

Mixing a first carrier, optionally existing structure auxiliary agents and a first active ingredient precursor solution, and drying to obtain a first mixed product;

calcining the first mixed product to obtain first catalyst powder;

Preparing the first catalyst powder into slurry, and extruding to form or coating the slurry on a substrate to obtain a first catalyst precursor;

And drying and calcining the first catalyst precursor to obtain the first catalyst.

The invention further provides a catalyst comprising a second catalyst according to the invention.

dissolving a precursor of the second carrier in a solvent to obtain a second carrier precursor solution;

mixing the second carrier precursor solution with an alkaline precipitant and drying to obtain a second carrier dried product;

Calcining the second carrier dried product to obtain a second carrier;

Dissolving a precursor of the second active ingredient and a cosolvent in a solvent to obtain a precursor solution of the second active ingredient;

Mixing a second carrier, optionally existing structure auxiliary agents and a second active ingredient precursor solution, and drying to obtain a second mixed product;

Calcining the second mixed product to obtain second catalyst powder;

Preparing the second catalyst powder into slurry, and extruding to form or coating the slurry on a substrate to obtain a second catalyst precursor;

and drying and calcining the second catalyst precursor to obtain the second catalyst.

ADVANTAGEOUS EFFECTS OF INVENTION

Compared with the prior art, the invention has at least one of the following beneficial effects:

(1) The method for removing the nitrogen oxides, the mercury and the dioxin is simple and feasible, convenient to operate, has wide application prospect and is suitable for industrial batch production.

(2) The catalyst for removing nitrogen oxides, mercury and dioxin prepared by the invention shows good activity of NH ₃ selective reduction NO at the temperature of 250-350 ℃, hg ⁰ oxidation efficiency, dioxin (chlorobenzene) conversion rate and stable sulfur and water resistance.

(3) The catalyst for removing nitrogen oxides, mercury and dioxin prepared by the invention can be used in one SCR reactor, reduces the industrial cost, solves the space limitation, does not need to separate SCR and Hg ⁰ and dioxin (chlorobenzene) oxidation units, and has environmental friendliness and environmental protection.

Drawings

FIG. 1 shows an integrated tandem process and corresponding performance curves of a method of the present invention for removing nitrogen oxides, mercury, and dioxins in an applied process;

Fig. 2 shows a split-type tandem process and corresponding performance curves of another method of the present invention for removing nitrogen oxides, mercury, and dioxins in an application process.

Detailed Description

Various exemplary embodiments, features and aspects of the invention are described in detail below. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better illustration of the invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well known methods, procedures, means, equipment and steps have not been described in detail so as not to obscure the present invention.

Unless otherwise indicated, all units used in this specification are units of international standard, and numerical values, ranges of values, etc. appearing in the present invention are understood to include systematic errors unavoidable in industrial production.

In the present specification, the meaning of "can" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

Reference throughout this specification to "some specific/preferred embodiments," "other specific/preferred embodiments," "an embodiment," and so forth, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the elements may be combined in any suitable manner in the various embodiments.

In the present specification, the numerical range indicated by the term "numerical value a to numerical value B" means a range including the end point numerical value A, B.

In the present specification, when "normal temperature" or "room temperature" is used, the temperature may be 10 to 40 ℃.

< First aspect >

First catalyst

The first aspect of the present invention provides a first catalyst first. The first catalyst of the present invention comprises a first carrier and a first active ingredient, and the content of the first carrier is 80 to 99%, based on 100% of the total mass of the first catalyst, for example: 82%, 84%, 86%, 88%, 92%, 94%, 96%, 98%, etc.; the content of the first active ingredient is 1-15%, for example: 2%, 4%, 6%, 8%, 10%, 12%, 14%, etc. When the content of the first carrier is 80 to 99% and the content of the first active ingredient is 1 to 15%, the catalytic performance of the first catalyst is excellent.

In the invention, the primary function of the first carrier is to provide a large specific surface area, stability and mechanical strength, and a certain shape and size of the catalyst, so that the first active component is dispersed, the usage amount of the first active component is reduced, and the poisoning resistance of the catalyst is improved. The primary function of the first active component of the present invention is to provide an active site for NO _x removal. The first catalyst of the invention has an ammoxidation rate of less than 10% at 300 ℃.

In some specific embodiments, the first support comprises one or a combination of two or more of titanium oxide, aluminum oxide, cerium oxide, zirconium oxide, tin oxide, and silicon oxide; and/or the first active ingredient comprises one or more than two of vanadium oxide, iron oxide, copper oxide, tungsten oxide, molybdenum oxide and manganese oxide.

Specifically, the content of the titanium oxide in the first carrier is 75% to 90%, based on 100% of the total mass of the first catalyst, for example: 78%, 80%, 82%, 84%, 86%, 88%, etc.; the content of the aluminum oxide is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the cerium oxide content is 1% -10%, for example: 2%, 4%, 6%, 8%, etc.; the content of zirconium oxide is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the tin oxide content is 1% -10%, for example: 2%, 4%, 6%, 8%, etc.; the silicon oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.

The content of the vanadium oxide in the first active ingredient is 1% -3% based on 100% of the total mass of the first catalyst, for example: 1.5%, 2%, 2.5%, etc.; the iron oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the copper oxide content is 0% -1%, for example: 0.2%, 0.4%, 0.6%, 0.8%, etc.; the tungsten oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the molybdenum oxide content is 1% -5%, for example: 2%, 3%, 4%, etc.; the manganese oxide content is 1% -5%, for example: 2%, 3%, 4%, etc.

When the contents of the components of the first support and the first active material of the present invention are within the above-described ranges, the function of the first catalyst can be most effectively exhibited.

It should be noted that the total content of other impurity oxides in the first catalyst of the present invention should be less than 1%.

In some specific embodiments, the first catalyst also has sulfate ions therein; the sulfate ion content is 1.5 to 3% in terms of SO ₃, based on 100% of the total mass of the first catalyst, for example: 1.8%, 2%, 2.2%, 2.5%, 2.8%, etc.

In the present invention, the use of sulfate ions can enhance the ammonia adsorption promoting denitration activity of the reducing agent, and inhibit the excessive oxidation of ammonia molecules to inhibit the production of byproducts such as nitrous oxide. In general, sulfate ions in the catalyst come from sulfur-containing impurities of titanium dioxide, such as insufficient sulfate content, and sulfate substances are additionally added to improve the sulfur content in the finished catalyst.

In some specific embodiments, the first catalyst composition further has phosphate ions therein in an amount of less than 5%, preferably greater than 0% and less than 5%, based on the total mass of the first catalyst composition of 100%, based on P ₂O₅, for example: 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, etc. In the present invention, the phosphate ion can stabilize the first catalyst surface active site to maintain its configuration at high temperature (> 300 ℃); meanwhile, the method has the effects of enhancing ammonia adsorption and inhibiting the generation of nitrous oxide to a certain extent.

Process for the preparation of a first catalyst

The first aspect of the present invention also provides a process for the preparation of a first catalyst according to the present invention comprising the steps of:

calcining the first carrier dried product to obtain a first carrier;

calcining the first mixed product to obtain first catalyst powder;

For the precursor of the first support, one or a combination of two or more of the soluble salt of the first support or the oxide of the first support may be included. Specifically, the soluble salts may be one or a mixture of two or more of their respective inorganic acid salts such as nitrate, sulfate, hydrochloride, etc., or their hydrates, or may be one or a mixture of two or more of organic acid salts such as acetate, oxalate, etc., or their hydrates.

Likewise, for the first active ingredient precursor, one or a combination of two or more of the soluble salts of the first active ingredient is included. Specifically, the soluble salts may be one or a mixture of two or more of their respective inorganic acid salts such as nitrate, sulfate, hydrochloride, etc., or their hydrates, or may be one or a mixture of two or more of organic acid salts such as acetate, oxalate, etc., or their hydrates.

Specifically, the precursor of the first carrier comprises one or more than two of a titanium source, an aluminum source, a cerium source, a zirconium source, a tin source and a silicon source; the titanium source comprises one or more than two of titanium tetrachloride, titanium sulfate, tiO ₂, tetrabutyl titanate and titanium sol; the aluminum source comprises one or more than two of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum sol and the like; the cerium source comprises one or more than two of cerium chloride, cerium nitrate, cerium sulfate and the like; the zirconium source comprises one or more than two of zirconium chloride, zirconium nitrate, zirconium sulfate and the like; the tin source comprises one or more than two of tin chloride (stannic chloride), stannous chloride, stannous sulfate, stannous nitrate, stannous oxalate and the like; the silicon source comprises one or more of silicon dioxide, silicic acid, aluminum silicate, silica sol and the like.

The first active ingredient precursor comprises one or more than two of a vanadium source, an iron source, a copper source, a tungsten source, a molybdenum source and a manganese source. The vanadium source comprises one or a combination of more than two of ammonium metavanadate, vanadyl sulfate and vanadium tetrachloride; the iron source comprises one or more than two of ferrous sulfate, ferric chloride and ferric nitrate; the copper source comprises one or more than two of copper sulfate, copper chloride and copper nitrate; the tungsten source comprises one or a combination of more than two of ammonium tungstate, ammonium meta-tungstate and ammonium paratungstate; the molybdenum source comprises one or more than two of ammonium meta-molybdate, ammonium molybdate and ammonium paramolybdate; the manganese source comprises one or more of manganese nitrate, manganese chloride, manganese sulfate and the like.

The solvent used for dissolving the first active ingredient precursor is not particularly limited, and may be some solvents commonly used in the art. For example: water, and the like. In addition, in dissolving the precursor, some co-solvents may be used in consideration of the dissolution.

The alkaline precipitant is not particularly limited, and may be any alkaline material commonly used in the art. For example: naOH, KOH, ammonia water and other common alkaline substances. The amount of the alkaline precipitant used is not particularly limited in the present invention, and the pH is usually adjusted to 8 to 11.

Further, a structural auxiliary agent can be added into the first mixed product, and the mass content of the structural auxiliary agent can be 1% -8%. In particular, in the present invention, the construction aid may be glass fiber, ceramic fiber, or the like.

For drying, in the present invention, the temperature at which the drying can be performed may be 50 to 90 ℃; the drying time is 2-20 h. The calcination may be performed by a staged activation method, specifically, may be performed at 150 to 200℃for 1 to 3 hours, and then at 400 to 600℃for 1 to 3 hours.

< Second aspect >

Second catalyst

The second aspect of the present invention provides first a second catalyst. The second catalyst of the present invention comprises a second carrier and a second active ingredient, the content of the second carrier being 80 to 99%, based on 100% of the total mass of the second catalyst, for example: 82%, 84%, 86%, 88%, 92%, 94%, 96%, 98%, etc.; the content of the second active ingredient is 1 to 15%, for example: 2%, 4%, 6%, 8%, 10%, 12%, 14%, etc.

The second catalyst has the mercury removal rate higher than 95% in the range of 200-350 ℃, the dioxin removal rate higher than 90% at 275 ℃, and has stable sulfur and water resistance.

In some specific embodiments, the second support comprises one or a combination of two or more of titanium oxide, aluminum oxide, cerium oxide, zirconium oxide, tin oxide, and silicon oxide; and/or the second active ingredient comprises one or more than two of ruthenium oxide, platinum oxide, cobalt oxide, gold oxide, vanadium oxide, iron oxide, copper oxide, molybdenum oxide and manganese oxide.

Specifically, the content of the titanium oxide in the second carrier is 70% to 90%, based on 100% of the total mass of the second catalyst, for example: 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, etc.; the content of the aluminum oxide is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the cerium oxide content is 1% -10%, for example: 2%, 4%, 6%, 8%, etc.; the content of zirconium oxide is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the tin oxide content is 1% -10%, for example: 2%, 4%, 6%, 8%, etc.; the silicon oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.

The content of the ruthenium oxide in the second active ingredient is 0.1% to 1%, based on 100% of the total mass of the second catalyst, for example: 0.3%, 0.5%, 0.7%, 0.9%, etc.; the platinum oxide content is 0% -1%, for example: 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, etc.; the cobalt oxide content is 1% -20%, for example: 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, etc.; the gold oxide content is 0% -1%, for example: 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, etc.; the vanadium oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the iron oxide content is 0% -1%, for example: 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, etc.; the copper oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the molybdenum oxide content is 0% -5%, for example: 1%, 2%, 3%, 4%, etc.; the manganese oxide content is 0% -10%, for example: 2%, 4%, 6%, 8%, etc.

When the contents of the respective components of the second support and the second active material of the present invention are within the above-described ranges, the function of the second catalyst can be most effectively exhibited.

It should be noted that the total content of other impurity oxides in the second catalyst of the present invention should be less than 1%.

In some specific embodiments, the second catalyst further has phosphate ions therein, the phosphate ions being present in an amount of 5% or less, preferably greater than 0% and 5% or less, based on the total mass of the second catalyst being 100%, based on P ₂O₅, for example: 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, etc. In the second catalyst of the present invention, the phosphate ions enhance the catalyst loadingAnd Lewis acid sites, and the addition of phosphate groups enhances the interaction between the molecules on the catalyst surface by steric effects.

Process for preparing a second catalyst

The second aspect of the present invention also provides a process for preparing a second catalyst according to the present invention, comprising the steps of:

dissolving a second carrier precursor in a solvent to obtain a second carrier precursor solution;

Calcining the second carrier dried product to obtain a second carrier;

Calcining the second mixed product to obtain second catalyst powder;

For the precursor of the second support, one or a combination of two or more of a soluble salt of the second support or an oxide of the second support may be included. Specifically, the soluble salts may be one or a mixture of two or more of their respective inorganic acid salts such as nitrate, sulfate, hydrochloride, etc., or their hydrates, or may be one or a mixture of two or more of organic acid salts such as acetate, oxalate, etc., or their hydrates.

For the second active ingredient precursor, one or a combination of two or more of the soluble salts of the second active ingredient is included. Specifically, the soluble salts may be one or a mixture of two or more of their respective inorganic acid salts such as nitrate, sulfate, hydrochloride, etc., or their hydrates, or may be one or a mixture of two or more of organic acid salts such as acetate, oxalate, etc., or their hydrates.

Specifically, the precursor of the second carrier comprises one or more than two of a titanium source, an aluminum source, a cerium source, a zirconium source, a tin source and a silicon source; the titanium source comprises one or more than two of titanium tetrachloride, titanium sulfate, tiO ₂, tetrabutyl titanate and titanium sol; the aluminum source comprises one or more than two of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum sol and the like; the cerium source comprises one or more than two of cerium chloride, cerium nitrate, cerium sulfate and the like; the zirconium source comprises one or more than two of zirconium chloride, zirconium nitrate, zirconium sulfate and the like; the tin source comprises one or more than two of tin chloride (stannic chloride), stannous chloride, stannous sulfate, stannous nitrate, stannous oxalate and the like; the silicon source comprises one or more of silicon dioxide, silicic acid, aluminum silicate, silica sol and the like.

The second active ingredient precursor comprises one or more than two of ruthenium source, platinum source, cobalt source, gold source, vanadium source, iron source, copper source, molybdenum source and manganese source. The ruthenium source comprises one or more than two of ruthenium chloride, ruthenium nitrate and ruthenium sulfate; the platinum source comprises one or more of chloroplatinic acid, ammonium chloroplatinate and potassium chloroplatinate; the cobalt source comprises one or more than two of cobalt nitrate, cobalt chloride, cobalt sulfate and the like; the gold source comprises chloroauric acid; the vanadium source comprises one or more than two of ammonium metavanadate, vanadyl sulfate, vanadium tetrachloride and the like; the iron source comprises one or more than two of ferrous sulfate, ferric chloride, ferric nitrate and the like; the copper source comprises one or more than two of copper sulfate, copper chloride and copper nitrate; the molybdenum source comprises one or more than two of ammonium meta-molybdate, ammonium molybdate and ammonium paramolybdate; the manganese source comprises one or more of manganese nitrate, manganese chloride, manganese sulfate and the like.

The solvent used for dissolving the second active ingredient precursor is not particularly limited, and may be some solvents commonly used in the art. For example: water, and the like. In addition, in dissolving the precursor, some co-solvents may be used in consideration of the dissolution.

Further, a structural aid may be added to the second mixed product. The mass content of the structural auxiliary agent is 1% -8%. In particular, in the present invention, the construction aid may be glass fiber, ceramic fiber, or the like.

< Third aspect >

In a third aspect, the present invention provides a method for the synergistic removal of nitrogen oxides, mercury and dioxins, comprising the steps of:

a step of removing nitrogen oxides using a second catalyst;

And a step of removing dioxin and mercury by using a second catalyst.

In the present invention, the first catalyst and the second catalyst are located in the same reactor in a series process, i.e., a dual function reactor; in the integrated tandem method, the first catalyst accounts for 50% -80% of the total length of the substrate, and the second catalyst accounts for 20% -50% of the total length of the substrate. In the split-type tandem method, the first catalyst layer is close to the air inlet end, and the second catalyst layer is close to the air outlet end. In the integrated catalyst, the first catalyst accounts for 50% -80% of the total length of the substrate, and the second catalyst accounts for 20% -50% of the total length of the substrate.

The integrated serial connection method and the application process have the characteristics of small occupied area, simple and convenient operation, low energy consumption and the like, and can greatly reduce the flue gas treatment cost. The split type serial connection method and the application process have the characteristics of flexible installation, wide application range and the like, and can be modified based on the original flue gas treatment facilities.

The method for removing nitrogen oxides, mercury and dioxin provided by the invention has good denitration rate (70-99%) and mercury removal efficiency (80-95%) within the range of 200-350 ℃, and has stable sulfur and water resistance, wherein the removal rate of dioxin (chlorobenzene) is higher than 90% at 275 ℃.

Examples

Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1

(1) Preparation of the first catalyst

Dissolving titanium tetrachloride, silica sol, cerium nitrate and tin tetrachloride in a proper amount of water, adding alkaline precipitator ammonia water, controlling the pH to be 9, filtering and washing until the pH is about 7, drying at 60 ℃ for 10 hours, calcining at 180 ℃ for 2 hours, and calcining at 500 ℃ for 2 hours to obtain a catalyst carrier; then dissolving cosolvent monoethanolamine in a proper amount of water, and then adding ammonium metavanadate, ammonium metamolybdate, ammonium metatungstate, ammonium sulfate and ammonium phosphate for dissolution; and immediately adding the prepared catalyst carrier, adding glass fiber (3% of mass content), mixing, and extruding to obtain the honeycomb catalyst. Drying at 80 ℃ for 6 hours, calcining at 180 ℃ for 1 hour, calcining at 500 ℃ for 3 hours, and heating at a rate of 1 ℃/min to obtain the first catalyst.

The raw material ratio is calculated according to titanium dioxide (80 percent, the same mass fraction), aluminum oxide (3 percent), cerium oxide (3.5 percent), tin dioxide (5 percent), vanadium pentoxide (1.5 percent), molybdenum trioxide (1.5 percent), tungsten trioxide (1.5 percent), sulfate radical (2.5 percent) and phosphate radical (1.5 percent).

The ammonia oxidation efficiency of the catalyst is tested by adopting a mode of simulating actual working conditions, and the simulated gas components comprise: 500ppmNH ₃,6％O₂,N₂ is balance gas, the reaction is stable at 300 ℃, the airspeed is 80000h ^-1, the ammoxidation efficiency is tested by using a Gasmet portable Fourier transform infrared gas analyzer, and the ammoxidation rate of the obtained catalyst is about 1% at 300 ℃.

The specific surface area of the catalyst was achieved on a physical adsorption instrument in U.S. Micromeritics ASAP 2460,2460. After the test sample is subjected to N ₂ adsorption-desorption curve test at a low temperature of 77K, the specific surface area of the catalyst can be obtained by calculation through a Brunauer-EMMETTTELLER (BET) formula. Before the specific surface area is carried out, the catalyst must be subjected to vacuum degassing treatment at 300 ℃ for about 3 hours to remove impurities and water adsorbed on the surface of the catalyst, thereby ensuring accurate results. The specific surface area of the catalyst obtained was about 115m ²/g.

(2) Preparation of the second catalyst

Dissolving titanium sulfate, silica sol, cerium nitrate and stannous sulfate in a proper amount of water, adding an ammonia water alkaline precipitant, controlling the pH to be 10, filtering and washing until the pH is about 7, drying at 80 ℃ for 8 hours, calcining at 180 ℃ for 3 hours and calcining at 500 ℃ for 3 hours to obtain a catalyst carrier; then adding ruthenium nitrate, cobalt nitrate, ammonium meta-molybdate and ammonium phosphate for dissolution; and immediately adding the prepared catalyst carrier, adding glass fiber (the mass content is 2%) and ceramic fiber (the mass content is 1%), preparing slurry, coating the slurry on the catalyst carrier, drying at 80 ℃ for 6h, calcining at 180 ℃ for 2h, and calcining at 400 ℃ for 3h to obtain the second catalyst.

The raw material ratio is calculated according to titanium dioxide (77%, the same mass fraction), silicon dioxide (3%), cerium dioxide (6.5%), tin dioxide (5%), ruthenium dioxide (0.5%), tricobalt tetraoxide (3%), molybdenum trioxide (3%) and phosphate (2%).

The mercury and dioxin efficiency of the catalyst was tested in a manner simulating actual conditions (experiments were performed using the model compound chlorobenzene), and the simulated gas components included: 100ppm of chlorobenzene, 80ug/m ³ Hg⁰,6％O₂,N₂ is balance gas, the reaction is stable at 250-300 ℃, the airspeed is 80000h ^-1, the removal rate of chlorobenzene is tested by using a Gasmet portable Fourier transform infrared gas analyzer, the mercury removal efficiency is tested by using a Lumex RA-915+ mercury meter, the mercury removal efficiency of the obtained catalyst is 99% at 250 ℃, and the removal rate of chlorobenzene is higher than 90% at 275 ℃.

The specific surface area of the catalyst was achieved on a physical adsorption instrument in U.S. Micromeritics ASAP 2460,2460. After the test sample is subjected to N ₂ adsorption-desorption curve test at a low temperature of 77K, the specific surface area of the catalyst can be obtained by calculation through a Brunauer-EMMETTTELLER (BET) formula. Before the specific surface area is carried out, the catalyst must be subjected to vacuum degassing treatment at 300 ℃ for about 3 hours to remove impurities and water adsorbed on the surface of the catalyst, thereby ensuring accurate results. The specific surface area of the catalyst obtained was about 135m ²/g.

(3) Method for removing nitrogen oxides, dioxins and mercury

In this embodiment, a split type serial connection method and an application process are adopted, as shown in fig. 1, the first catalyst layer is close to the air inlet end, the second catalyst layer is close to the air outlet end, and the two catalysts can be closely contacted or have a certain distance. The first catalyst is placed in three layers and then the second catalyst is placed in three layers.

(4) Performance testing

The ammonia oxidation efficiency of the catalyst is tested by adopting a mode of simulating actual working conditions, and the simulated gas components comprise: 500ppm NH ₃, 500ppm NO,100ppm chlorobenzene (when needed), 80ug/m ³ Hg⁰,6％O₂,N₂ as balance gas, airspeed of 80000h ^-1, NO _x removal and chlorobenzene removal were tested by Gasmet portable Fourier transform infrared gas analyzer, and mercury removal was tested by Lumex RA-915+ mercury meter. The detection shows that (as shown in figure 1), the reaction temperature is 275-350 ℃, the NO _x removal rate is more than 90%, the mercury removal rate is 85%, and the chlorobenzene removal rate is more than 90%. However, when no chlorobenzene exists, the mercury removal rate is greatly reduced, and therefore, under the working condition, chlorine species in dioxin can be utilized to effectively promote mercury oxidation, so that the synergistic removal effect is achieved.

Pilot test experiment

In a pilot test of a certain garbage incineration power plant, three layers of first catalysts are placed on the upper layer, three layers of second catalysts are placed on the lower layer, the flue gas temperature is about 300 ℃ in 4000m ³/h, the NO _x removal rate and the dioxin removal rate are tested by using a Gasmet portable Fourier transform infrared gas analyzer, the mercury removal efficiency is tested by using a Lumex RA-915+ mercury meter, and the results are shown in Table 1.

Table 1 example 1 split process pilot effect

As can be seen from Table 1, the preparation method and the application process of the tandem catalyst for the synergistic removal of nitrogen oxides, mercury and dioxin have excellent denitration and demercuration performances.

Example 2

(1) Preparation of the first catalyst

Dissolving titanium sulfate, aluminum sol, ceric ammonium nitrate and tin tetrachloride in a proper amount of water, adding alkaline precipitator ammonia water and ammonium bicarbonate, controlling the pH value to be 10, filtering and washing until the pH value is about 7, drying at 70 ℃ for 9 hours, calcining at 200 ℃ for 1 hour, and calcining at 500 ℃ for 3 hours to obtain a catalyst carrier; then dissolving cosolvent monoethanolamine in a proper amount of water, and then adding ammonium metavanadate, ammonium metamolybdate, ammonium metatungstate, ammonium sulfate and ammonium phosphate for dissolution; immediately adding the prepared catalyst carrier, adding glass fiber (mass content 1.5%) and ceramic fiber (mass content 2%), drying at 90 ℃ for 5h, calcining at 180 ℃ for 1h, calcining at 500 ℃ for 4h, and heating at a rate of 1 ℃/min to obtain the powder of the first catalyst. Preparing slurry, forward coating the slurry on a substrate, wherein the first catalyst accounts for 70% of the total length of the substrate, drying at 80 ℃ for 6h, calcining at 180 ℃ for 2h, and calcining at 500 ℃ for 3h to obtain the first catalyst.

The raw material ratio is calculated according to titanium dioxide (82%, the same in mass fraction), aluminum oxide (2%), cerium oxide (3.5%), tin dioxide (4%), vanadium pentoxide (1.5%), molybdenum trioxide (1%), tungsten trioxide (2%), sulfate radical (2.5%) and phosphate radical (1.5%).

The ammonia oxidation efficiency of the catalyst is tested by adopting a mode of simulating actual working conditions, and the simulated gas components comprise: 500ppmNH ₃,6％O₂,N₂ is balance gas, the reaction is stable at 300 ℃, the airspeed is 80000h ^-1, the ammoxidation efficiency is tested by using a Gasmet portable Fourier transform infrared gas analyzer, and the ammoxidation rate of the obtained catalyst is about 2% at 300 ℃.

The specific surface area of the catalyst was achieved on a physical adsorption instrument in U.S. Micromeritics ASAP 2460,2460. After the test sample is subjected to N ₂ adsorption-desorption curve test at a low temperature of 77K, the specific surface area of the catalyst can be obtained by calculation through a Brunauer-EMMETTTELLER (BET) formula. Before the specific surface area is carried out, the catalyst must be subjected to vacuum degassing treatment at 300 ℃ for about 3 hours to remove impurities and water adsorbed on the surface of the catalyst, thereby ensuring accurate results. The specific surface area of the catalyst obtained was about 110m ²/g.

(2) Preparation of the second catalyst

Dissolving tetrabutyl titanate, silica sol, cerium nitrate and stannous sulfate in a proper amount of water, adding alkaline precipitator ammonia water, controlling the pH value to be 9, filtering and washing until the pH value is about 7, drying at 80 ℃ for 10 hours, calcining at 180 ℃ for 3 hours and calcining at 450 ℃ for 2 hours to obtain a catalyst carrier; then adding ruthenium nitrate, cobalt nitrate, ammonium meta-molybdate and ammonium phosphate for dissolution; immediately adding the prepared catalyst carrier, adding glass fiber (mass content 2%) and ceramic fiber (mass content 2%), drying at 90 ℃ for 5h, calcining at 180 ℃ for 1h, and calcining at 400 ℃ for 4h to obtain the powder of the second catalyst. Preparing slurry, reversely coating the slurry on a substrate, wherein the second catalyst accounts for 30% of the total length of the substrate, drying the slurry at 60 ℃ for 10 hours, calcining the slurry at 180 ℃ for 3 hours, and calcining the slurry at 450 ℃ for 3 hours to obtain the serial catalyst with the first catalyst and the second catalyst.

The raw material ratio is calculated according to titanium dioxide (79%, the same in mass fraction), silicon dioxide (3%), cerium dioxide (7.5%), tin dioxide (3%), ruthenium dioxide (0.5%), tricobalt tetraoxide (4%), molybdenum trioxide (2%) and phosphate (1%).

The mercury and dioxin efficiency of the catalyst was tested in a manner simulating actual conditions (experiments were performed using the model compound chlorobenzene), and the simulated gas components included: 100ppm of chlorobenzene, 80ug/m ³ Hg⁰,6％O₂,N₂ is balance gas, the reaction is stable at 250-300 ℃, the airspeed is 80000h ^-1, the removal rate of chlorobenzene is tested by using a Gasmet portable Fourier transform infrared gas analyzer, the mercury removal efficiency is tested by using a Lumex RA-915+ mercury meter, the mercury removal efficiency of the obtained catalyst is 99% at 250 ℃, and the chlorobenzene removal rate is higher than 90% at 275 ℃.

The specific surface area of the catalyst was achieved on a physical adsorption instrument in U.S. Micromeritics ASAP 2460,2460. After the test sample is subjected to N ₂ adsorption-desorption curve test at a low temperature of 77K, the specific surface area of the catalyst can be obtained by calculation through a Brunauer-EMMETTTELLER (BET) formula. Before the specific surface area is carried out, the catalyst must be subjected to vacuum degassing treatment at 300 ℃ for about 3 hours to remove impurities and water adsorbed on the surface of the catalyst, thereby ensuring accurate results. The specific surface area of the catalyst obtained was about 175m ²/g.

(3) Method for removing nitrogen oxides, dioxins and mercury

This embodiment employs an integrated tandem process and application process, as shown in fig. 2, wherein the first catalyst comprises 70% of the total length of the substrate and the second catalyst comprises 30% of the total length of the substrate. The end coated with the first catalyst is placed at the intake end when placed.

(4) Performance testing

The ammonia oxidation efficiency of the catalyst is tested by adopting a mode of simulating actual working conditions, and the simulated gas components comprise: 500ppm NH ₃, 500ppm NO,100ppm chlorobenzene (when needed), 80ug/m ³ Hg⁰,6％O₂,N₂ as balance gas, airspeed of 80000h ^-1, NO _x removal and chlorobenzene removal were tested by Gasmet portable Fourier transform infrared gas analyzer, and mercury removal was tested by Lumex RA-915+ mercury meter. The detection shows that (as shown in figure 2), the reaction temperature is 275-350 ℃, the NO _x removal rate is more than 90%, the mercury removal rate is 80%, and the chlorobenzene removal rate is more than 90%. However, when no chlorobenzene exists, the mercury removal rate is greatly reduced, and therefore, under the working condition, chlorine species in dioxin can be utilized to effectively promote mercury oxidation, so that the synergistic removal effect is achieved.

Pilot test experiment

And (3) performing a pilot test in a certain garbage incineration power plant, wherein the first catalyst accounts for 70% of the total length of the substrate, and the second catalyst accounts for 30% of the total length of the substrate. When the catalyst is placed, one end coated with the first catalyst is placed at an air inlet end, the flue gas is 4000m ³/h, the inlet flue gas temperature is about 300 ℃, the removal rate of NO _x and the removal rate of dioxin are tested by using a Gasmet portable Fourier transform infrared gas analyzer, the mercury removal efficiency is tested by using a Lumex RA-915+ mercury meter, and the results are shown in Table 2.

Table 2 example 2 integrated process pilot effect

As can be seen from Table 2, the preparation method and the application process of the tandem catalyst for the synergistic removal of nitrogen oxides, mercury and dioxin have excellent denitration and demercuration performances.

It should be noted that, although the technical solution of the present invention is described in specific examples, those skilled in the art can understand that the present invention should not be limited thereto.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the technical improvements in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. The method for cooperatively removing the nitrogen oxide, the mercury and the dioxin is characterized by comprising the following steps of:

a step of removing nitrogen oxides using a first catalyst;

A step of removing dioxin and mercury by using a second catalyst; wherein,

The second catalyst comprises a second carrier and a second active ingredient, wherein the content of the second carrier is 80-99% based on 100% of the total mass of the second catalyst; the content of the second active ingredient is 1-15%;

The second support comprises titanium oxide, cerium oxide, and tin oxide; the second active ingredient comprises ruthenium oxide and cobalt oxide; wherein,

The content of the titanium oxide in the second carrier is 70% -90%, the content of the cerium oxide is 1% -10% and the content of the tin oxide is 1% -10% based on 100% of the total mass of the second catalyst;

The content of the ruthenium oxide in the second active component is 0.1% -1% and the content of the cobalt oxide is 1% -14% based on 100% of the total mass of the second catalyst.

2. The method according to claim 1, wherein the first catalyst comprises a first carrier and a first active ingredient, the content of the first carrier being 80-99% based on 100% of the total mass of the first catalyst; the content of the first active ingredient is 1-15%.

3. The method of claim 2, wherein the first support comprises one or a combination of two or more of titanium oxide, aluminum oxide, cerium oxide, zirconium oxide, tin oxide, and silicon oxide; and/or

4. A method according to claim 3, wherein the first carrier has a content of the titanium oxide of 75% to 90%, a content of the aluminum oxide of 0% to 5%, a content of the cerium oxide of 1% to 10%, a content of the zirconium oxide of 0% to 5%, a content of the tin oxide of 1% to 10%, and a content of the silicon oxide of 0% to 5%, based on 100% of the total mass of the first catalyst; and/or

5. The method of any one of claims 1-4, wherein the first catalyst further has sulfate ions therein; the content of sulfate ions is 1.5-3% calculated by SO ₃ and calculated by 100% of the total mass of the first catalyst; and/or

6. The method of any one of claims 1-4, wherein the second support further comprises a combination of one or more of aluminum oxide, zirconium oxide, and silicon oxide; and/or

The second active ingredient further comprises one or a combination of more than two of platinum oxide, gold oxide, vanadium oxide, iron oxide, copper oxide, molybdenum oxide and manganese oxide.

7. The method according to claim 6, wherein the content of the aluminum oxide in the second carrier is 0% to 5%, the content of the zirconium oxide is 0% to 5%, and the content of the silicon oxide is 0% to 5%, based on 100% of the total mass of the second catalyst; and/or

In the second active component, the content of the platinum oxide is 0% -1%, the content of the gold oxide is 0% -1%, the content of the vanadium oxide is 0% -5%, the content of the iron oxide is 0% -1%, the content of the copper oxide is 0% -5%, the content of the molybdenum oxide is 0% -5%, and the content of the manganese oxide is 0% -10% based on 100% of the total mass of the second catalyst.

8. The method according to any one of claims 1 to 4, wherein the second catalyst further has phosphate ions therein, and the content of phosphate ions is 5% or less in terms of P ₂O₅, based on 100% by mass of the total mass of the second catalyst.

9. The method according to any one of claims 1 to 4, wherein the preparation method of the first catalyst comprises the steps of:

calcining the first carrier dried product to obtain a first carrier;

calcining the first mixed product to obtain first catalyst powder;

10. The method according to any one of claims 1 to 4, wherein the preparation method of the second catalyst comprises the steps of:

Calcining the second carrier dried product to obtain a second carrier;

Calcining the second mixed product to obtain second catalyst powder;