CN106669728A - Integral-type low-temperature SCR denitration catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses an integral low-temperature SCR denitrification catalyst and a preparation method thereof. The catalyst comprises: 24-48% of titanium dioxide, 12-16% of manganese oxide, 1-10% of holmium trioxide, 5% of ferric oxide ～9%, glass fiber 3～8%, carboxymethyl cellulose 2～5%, glycerin 3～6%, activated carbon powder 0.7～2% and water 21～26%; the preparation method is to oxidize titanium dioxide and manganese compound, holmium oxide, ferric oxide, glass fiber, carboxymethyl cellulose and activated carbon powder, add glycerin and water to make a paste; age the paste, mold it, dry and calcinate . The advantage is that the denitration catalyst has good low-temperature activity, that is, at 120°C, the _NOx conversion rate can reach about 95%, the denitration efficiency is high, and the mechanical properties are strong; at the same time, the preparation method is strong in operability and can obtain ideal Excellent catalyst molding effect, simple process and high yield.

Description

A kind of monolithic low-temperature SCR denitrification catalyst and preparation method thereof

technical field

The invention belongs to the technical field of catalysts, and in particular relates to an integral low-temperature SCR denitration catalyst and a preparation method thereof.

Background technique

Ammonia Selective Catalytic Reduction (NH ₃ -SCR) is currently the most efficient and widely used flue gas denitrification technology. Nitrogen oxides (NO _x ) were removed using this method. Catalyst is the core part of NH ₃ -SCR denitrification technology. At present, most commercial catalysts are V ₂ O ₅ -WO ₃ (MoO ₃ )/TiO ₂ catalysts, whose working temperature is generally in the range of 300-450°C, which is a medium-temperature catalyst. However, the raw materials and equipment for the preparation of monolithic denitration catalysts in my country still mainly rely on the introduction of foreign advanced technology, and the molding and preparation technology of monolithic catalysts still lags behind foreign countries, and there is a big gap.

At present, China's SCR denitrification process mostly adopts high-temperature and high-dust arrangement. During the operation, the commercial monolithic catalyst is washed by soot and fly ash for a long time, which is easy to cause wear and blockage. SO ₂ , water vapor, and alkaline earth in the soot and fly ash Metals, heavy metals, etc. will cause the poisoning and deactivation of the monolithic catalyst. Therefore, the research and development of an integrated low-temperature SCR denitrification catalyst suitable for low-temperature and low-dust arrangement technology has extremely important practical significance and development prospects.

Contents of the invention

Purpose of the invention: the first purpose of the present invention is to provide a monolithic low-temperature SCR denitration catalyst with good low-temperature activity; another purpose of the present invention is to provide a preparation method of the catalyst.

Technical solution: The integral low-temperature SCR denitrification catalyst of the present invention comprises the following raw materials in terms of mass percentage: 24-48% of titanium dioxide, 12-16% of manganese oxide, 1-10% of holmium trioxide, 5-5% of ferric oxide 9%, glass fiber 3-8%, carboxymethyl cellulose 2-5%, glycerin 3-6%, activated carbon powder 0.7-2% and water 21-26%.

By adding glass fiber, carboxymethyl cellulose, glycerin, activated carbon powder and water, the present invention further improves the cohesiveness between raw materials, increases the specific surface area of the catalyst, and makes the prepared monolithic low-temperature SCR denitrification catalyst not only have Good low temperature activity and strong mechanical properties. Preferably, the raw materials may include: 29-31% of titanium dioxide, 12-14% of manganese oxide, 6-8% of holmium trioxide, 7-9% of ferric oxide, 5-7% of glass fiber, carboxymethyl Cellulose 2-4%, glycerin 5-6%, activated carbon powder 0.8-1% and water 23-25%.

Furthermore, the manganese oxide used in the present invention includes at least one of MnO ₂ , Mn ₂ O ₃ or Mn ₃ O ₄ . The particle size of the glass fiber is 100-200 mesh.

The method for preparing the monolithic low-temperature SCR denitration catalyst of the present invention comprises the following steps:

(1) Titanium dioxide, manganese oxide, holmium sesquioxide, ferric oxide, glass fiber, carboxymethyl cellulose and activated carbon powder are mixed by mass percentage, and glycerin and water are added to prepare a paste;

(2) After the above paste is aged, molded, dried and calcined, an integral low-temperature SCR denitration catalyst is prepared.

Furthermore, in step (2), the paste is aged for 5-7 hours to enhance the plasticity of the paste; compression molding is carried out under the condition of 10-12 MPa.

Furthermore, in step (2), the drying is first dried at 50-70°C for 11-13 hours, then dried at 70-90°C for 7-9 hours, and finally dried at 100-120°C for 3-5 hours. The three-stage drying method is adopted to prevent the water from evaporating too quickly, so as to prevent the green body from cracking. For calcination, the temperature is raised to 200-400°C at a rate of 4-6°C/min and maintained for 2-4 hours, and then the temperature is raised to 400-600°C at a rate of 4-6°C/min and maintained for 4-6 hours. In the present invention, the temperature is raised at a rate of 4-6° C./min, which further improves the mechanical strength of the denitrification catalyst.

Beneficial effects: Compared with the prior art, the significant advantages of the present invention are: the integral SCR denitration catalyst has good low-temperature activity, that is, under the condition of 120°C, the NO _x conversion rate can be as high as about 95%, and the denitration efficiency is high. And the mechanical performance is strong; at the same time, the preparation method has strong operability, can obtain an ideal catalyst forming effect, and has a simple process and a high yield.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the examples.

Example 1

(1) Mixture: 48% titanium dioxide, 16% manganese oxide, 1% holmium sesquioxide, 5% ferric oxide, 3% glass fiber, 2% carboxymethyl cellulose and 1% activated carbon powder Mix and stir evenly for 15 minutes to prepare a solid-phase mixture; wherein, the manganese oxide includes at least one of MnO ₂ , Mn ₂ O ₃ or Mn ₃ O ₄ .

(2) Kneading: Add 3% glycerin and 21% water into the solid-phase mixture, and knead for 30 minutes to obtain a mud ball with uniform texture.

(3) Mud practice: practice mud 4 times under an external pressure of 2MPa to obtain a compact plastic paste.

(4) Aging: Seal and age the plastic paste at room temperature for 5 hours.

(5) Molding: the paste obtained in step (5) is molded and shaped under a pressure of 10 MPa, and a honeycomb molded green body is obtained after demoulding.

(6) Drying: Dry the molded body at 50°C for 11h, then at 70°C for 7h, and finally at 100°C for 3h

(7) Roasting: The dried molded body is first heated to 200°C at a rate of 4°C/min and maintained for 2h, then raised to 400°C at a rate of 4°C/min and maintained for 4h, and obtained after natural cooling The finished product of integral honeycomb low-temperature SCR denitration catalyst.

The integrated low-temperature SCR denitration catalyst prepared in Example 1 was placed in a simulated reactor for activity evaluation, and the reaction gas composition was Ф(NO)=Ф(NH ₃ )=0.08% (volume fraction), Ф(O ₂ )= 5% (volume fraction), N ₂ as balance gas, space velocity 4000h ^-1 , and under the condition of 120°C, the measured _NOx conversion rate of the monolithic low-temperature SCR catalyst is 80%.

Example 2

(1) Mixture: 24% titanium dioxide, 12% manganese oxide, 8% holmium sesquioxide, 9% ferric oxide, 8% glass fiber, 5% carboxymethyl cellulose and 2% activated carbon powder Mix and stir evenly for 20 minutes to prepare a solid-phase mixture; wherein, the manganese oxide includes at least one of MnO ₂ , Mn ₂ O ₃ or Mn ₃ O ₄ .

(2) Kneading: Add 6% glycerin and 26% water into the solid-phase mixture, and knead for 40 minutes to obtain a mud ball with uniform texture.

(3) Mud practice: practice mud 5 times under an external pressure of 3MPa to obtain a compact plastic paste.

(4) Aging: Seal and age the plastic paste at room temperature for 7 hours to further enhance the plasticity of the paste.

(5) Molding: the paste obtained in step (5) is molded and shaped under a pressure of 12 MPa, and a honeycomb shaped green body is obtained after demoulding.

(6) Drying: Dry the molded body at 70°C for 13h, then at 90°C for 9h, and finally at 120°C for 5h

(7) Roasting: The dried molded body is first heated to 400°C at a rate of 6°C/min and maintained for 4h, then raised to 600°C at a rate of 6°C/min and maintained for 6h, and then obtained after natural cooling The finished product of integral honeycomb low-temperature SCR denitration catalyst.

The monolithic low-temperature SCR denitration catalyst prepared in Example 2 was placed in a simulated reactor for activity evaluation, and the reaction gas composition was Ф(NO)=Ф(NH ₃ )=0.08% (volume fraction), Ф(O ₂ ) =5% (volume fraction), N ₂ is the balance gas, the space velocity is 4000h ^-1 , and under the condition of 120°C, the measured NO _x conversion rate of the monolithic low-temperature SCR catalyst is 85%.

Example 3

(1) Mixture: 30% titanium dioxide, 13% manganese oxide, 7% holmium sesquioxide, 9% ferric oxide, 6% glass fiber, 3% carboxymethyl cellulose and 1% activated carbon powder Mix and stir evenly for 20 minutes to prepare a solid-phase mixture; wherein, the manganese oxide includes at least one of MnO ₂ , Mn ₂ O ₃ or Mn ₃ O ₄ .

(2) Kneading: Add 6% glycerin and 25% water into the solid-phase mixture, and knead for 40 minutes to obtain a mud ball with uniform texture.

(3) Mud practice: practice mud 5 times under an external pressure of 2MPa to obtain a compact plastic paste.

(4) Aging: Seal and age the plastic paste at room temperature for 6 hours to further enhance the plasticity of the paste.

(5) Molding: the paste obtained in step (5) is molded and shaped under a pressure of 10 MPa, and a honeycomb molded green body is obtained after demoulding.

(6) Drying: The molded body was first dried at 60°C for 12 hours, then at 80°C for 8 hours, and finally at 110°C for 4 hours.

(7) Roasting: The dried molded body is first heated to 300°C at a rate of 5°C/min and maintained for 3h, then raised to 500°C at a rate of 5°C/min and maintained for 5h, and obtained after natural cooling The finished product of integral honeycomb low-temperature SCR denitration catalyst.

The monolithic low-temperature SCR denitration catalyst prepared in Example 3 was placed in a simulated reactor for activity evaluation, and the reaction gas composition was Ф(NO)=Ф(NH ₃ )=0.08% (volume fraction), Ф(O ₂ ) =5% (volume fraction), N ₂ is the balance gas, and the space velocity is 4000h ^-1 . Under this condition, the measured _NOx conversion rate of the monolithic low-temperature SCR catalyst is 95%.

Example 4

The steps are basically the same as in Example 3, except that the component content of each raw material is specifically: 24% titanium dioxide, 12% manganese oxide, 10% holmium sesquioxide, 7% ferric oxide, 8% glass Fiber, 5% carboxymethyl cellulose, 6% glycerin, 2% activated charcoal powder and 26% water.

Example 5

The steps are basically the same as in Example 3, except that the component content of each raw material is specifically: 29% titanium dioxide, 14% manganese oxide, 8% holmium sesquioxide, 9% ferric oxide, 5% glass Fiber, 4% Carboxymethyl Cellulose, 5% Glycerin, 1% Activated Carbon Powder and 25% Water.

Example 6

The steps are basically the same as in Example 3, except that the component content of each raw material is specifically: 31% titanium dioxide, 14% manganese oxide, 7.2% holmium sesquioxide, 7% ferric oxide, 7% glass Fiber, 2% carboxymethyl cellulose, 6% glycerin, 0.8% activated carbon powder and 25% water.

Example 7

The steps are basically the same as in Example 3, except that the component content of each raw material is specifically: 31% titanium dioxide, 12% manganese oxide, 6% holmium oxide, 9% ferric oxide, 7% glass Fiber, 4% carboxymethyl cellulose, 6% glycerin, 1% activated charcoal powder and 24% water.

Comparative example 1

The steps are basically the same as in Example 3, the difference being the component content of each raw material, specifically: 22% titanium dioxide, 25% manganese oxide, 0.5% holmium oxide, 15% ferric oxide, 1% glass Fiber, 10% carboxymethyl cellulose, 1% glycerin, 7% activated carbon powder and 18.5% water.

Comparative example 2

The steps are basically the same as in Example 3, except that the component content of each raw material is specifically: 52% titanium dioxide, 8% manganese oxide, 12% holmium oxide, 3% ferric oxide, 12% glass Fiber, 1% carboxymethyl cellulose, 9% glycerin, 0.5% activated carbon powder and 2.5% water.

The monolithic low-temperature SCR denitrification catalysts made in Examples 4-7 and Comparative Examples 1-2 were placed in a simulated reactor for activity evaluation, and the reaction gas composition was Ф(NO)=Ф(NH ₃ )=0.08% (volume fraction), Ф(O ₂ )=5% (volume fraction), N ₂ is the balance gas, and the space velocity is 4000h ^-1 . Under this condition, the measured NO _x conversion rate of the monolithic low-temperature SCR catalyst is shown in Table 1.

Table 1:

It can be seen from Table 1 that the denitration catalyst prepared by using the raw materials within the content range of the present invention has excellent low-temperature activity, high denitration rate, and strong mechanical properties.

Claims (9)

1. a kind of integrated low temperature SCR denitration, it is characterised in that the catalyst includes following former by mass percentage Material：The oxide 12~16% of titanium dioxide 24~48%, manganese, holmium oxide 1~10%, di-iron trioxide 5~9%, glass Glass fiber 3~8%, carboxymethylcellulose calcium 2~5%, glycerine 3~6%, activated carbon powder 0.7~2% and water 21~26%.

2. integrated low temperature SCR denitration according to claim 1, it is characterised in that：The titanium dioxide 29~ 31%th, the oxide 12~14% of manganese, holmium oxide 6~8%, di-iron trioxide 7~9%, glass fibre 5~7%, carboxylic first Base cellulose 2~4%, glycerine 5~6%, activated carbon powder 0.8~1% and water 23~25%.

3. integrated low temperature SCR denitration according to claim 1 and 2, it is characterised in that：The oxide of the manganese At least include MnO₂、Mn₂O₃Or Mn₃O₄In one kind.

4. integrated low temperature SCR denitration according to claim 1, it is characterised in that：The grain of the glass fibre Footpath is 100~200 mesh.

5. a kind of method of the integrated low temperature SCR denitration prepared described in claim 1, it is characterised in that including as follows Step：

(1) by mass percentage by titanium dioxide, the oxide of manganese, holmium oxide, di-iron trioxide, glass fibre, carboxylic first After base cellulose and activated carbon powder mixing, G ＆ W is added, lotion is obtained；

(2) after by above-mentioned lotion ageing, compression molding, drying and calcining, that is, integrated low temperature SCR denitration is obtained.

6. the method for preparing integrated low temperature SCR denitration according to claim 5, it is characterised in that：Step (2) In, the time of the ageing is 5~7h.

7. the method for preparing integrated low temperature SCR denitration according to claim 5, it is characterised in that：Step (2) In, the compression molding is carried out under the conditions of 10~12MPa.

8. the method for preparing integrated low temperature SCR denitration according to claim 5, it is characterised in that：Step (2) In, the drying is that 11~13h is first dried at 50~70 DEG C, and 7~9h is then dried at 70~90 DEG C, finally 100~ 3~5h is dried at 120 DEG C.

9. the method for preparing integrated low temperature SCR denitration according to claim 5, it is characterised in that：Step (2) In, the calcining is first to be warming up to 200~400 DEG C with the speed of 4~6 DEG C/min and be incubated 2~4h, then with 4~6 DEG C/min's Speed is warming up to 400~600 DEG C and is incubated 4~6h.