High-temperature denitration catalyst, preparation method and application

Abstract

The high-temperature denitration catalyst provided by the invention comprises a vanadium-containing active matter and a tungsten-containing active matter, the content of the vanadium-containing active matter in the catalyst is calculated by vanadium element, and the mass percent of the vanadium element in the catalyst is 1-3%; the content of the tungsten-containing active matter in the catalyst is calculated by tungsten element, and the mass percent of the tungsten element in the catalyst is 4-10%. The method has the advantage that the difficult problem is effectively solved by accurately adjusting the contents of the active components vanadium and tungsten. By means of precise regulation and control of the proportion of vanadium and tungsten, active sites are still stable at high temperature, good catalytic performance is maintained, and the monolithic catalyst can continuously and stably work at the high temperature of 400 DEG C or above. Due to the characteristic, the application scene of the catalyst is greatly widened, and the catalyst has extremely high application value for high-temperature industrial reaction and improvement of production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental control and pollution treatment, and specifically relates to a high-temperature denitration catalyst, a preparation method and an application thereof. Background Art

[0002] With the acceleration of the industrialization process, nitrogen oxides (NOx) have become one of the core sources of air pollution, and the research and application of their catalytic conversion technology are crucial for environmental protection. At present, although the mainstream zeolite-based catalysts, noble metal catalysts and metal oxide catalysts are widely used in industry, they all have significant technical bottlenecks. For example, common zeolite-based catalysts, represented by molecular sieves such as ZSM-5 and SAPO-34, achieve selective catalytic reduction (SCR) by ion-exchanging and loading transition metals (such as Cu, Fe). Their advantage lies in the medium and low temperature activity window (150 - 300 °C), which is suitable for diesel vehicle exhaust treatment. However, when applied under high temperature conditions, a better denitration effect cannot be achieved. Furthermore, common noble metal catalysts with platinum (Pt) and palladium (Pd) as active components are commonly used in three-way catalytic converters. Their high oxidation-reduction ability can simultaneously remove CO, HC and NOx, but they are costly and rely on imports, and are prone to sintering and deactivation at high temperatures.

[0003] In summary, the existing catalyst technology has significant shortcomings in terms of cost, stability and environmental adaptability, which restricts the in-depth treatment of NOx. Therefore, it is of great significance to develop a high-temperature denitration catalyst with high activity, high stability and long life in a high-temperature flue gas environment. Summary of the Invention

[0004] The purpose of the present invention is to solve the above technical problems of the existing technology.

[0005] To achieve the purpose of the present invention, the technical solution provided by the present invention is that a high-temperature denitration catalyst provided by the present invention includes a vanadium-containing active substance and a tungsten-containing active substance. The content of the vanadium-containing active substance in the catalyst is calculated based on vanadium element, and the mass percentage of vanadium element in the catalyst is 1 - 3%; the content of the tungsten-containing active substance in the catalyst is calculated based on tungsten element, and the mass percentage of tungsten element in the catalyst is 4 - 10%. By adjusting the contents of the active components vanadium and tungsten, the overall catalyst can also work under high temperature conditions above 400 °C.

[0006] Further, the catalyst further includes a titanium-containing carrier. The content of the titanium-containing carrier in the catalyst is calculated based on titanium element, and the mass percentage of titanium element in the catalyst is 50 - 80%. The titanium carrier is any one of titanium dioxide, zinc titanate, aluminum titanate, titanium silicon molecular sieve, nitrogen-doped titanium dioxide, barium titanate, and lanthanum titanate. The selected titanium-containing carrier can be combined with the active substance to obtain a catalyst that can also be used at high temperature.

[0007] Furthermore, the catalyst further includes a binder, and the balance in the catalyst is the binder, and the binder is carboxymethyl cellulose. The screened usable binder can, firstly, be combined with the active substance and the carrier to form a shaped honeycomb catalyst, and secondly, will not affect the function of the catalyst.

[0008] Furthermore, this catalyst of the present invention is a body-shaped honeycomb catalyst. Selecting to make such a honeycomb catalyst has a large specific surface area, can enable the flue gas to be in full contact with the catalyst, improve the catalytic efficiency, and has a large flue gas flow area and less consumption. The production process is reasonable, the active components are evenly distributed, and the anti-poisoning ability is strong.

[0009] The present invention also provides a preparation method of the above catalyst. The carrier, the active substance, and the binder are mixed and kneaded into a mud, and then the mud is aged and extruded into a honeycomb-shaped formed sample, and then the formed sample is dried and calcined to obtain the finished catalyst.

[0010] Furthermore, the carrier, the active substance, the binder, and water are mixed and stirred at 2000 - 5000 r / min for 3 - 6 h to obtain the mud. The mud is aged for 24 h - 48 h, and then the mud is filtered under vacuum conditions to remove impurities and air therein; then the mud is extruded into a shape, the extrusion pressure is 5 - 10 MPa, and the extrusion speed is 1.5 - 3 m / min to obtain the formed sample. Finally, the formed sample is dried, the drying time is 10 - 20 days, and the dried sample is calcined at 500 - 650 °C for 3 - 4 hours to finally obtain the catalyst.

[0011] The preparation method provided by the present invention is simple and easy to operate and is suitable for large-scale production.

[0012] The present invention also provides an application of the catalyst, which is used as a denitration catalyst for a working environment above 400 °C. The raw materials and the preparation method used in the catalyst of the present invention enable the prepared catalyst to still be usable under the high-temperature condition of 400 °C, expanding the application range of the catalyst. For example, the working environments in the shipbuilding industry and the ethylene cracking furnace industry mostly exceed 400 °C. Using the catalyst provided by the present invention breaks through the bottleneck of the prior art in treating nitrogen oxides in a high-temperature environment.

[0013] In summary, the beneficial effects of the present invention are as follows. Currently, most catalysts will have a significant reduction in catalytic activity or even deactivation at high temperatures above 400°C, severely limiting their scope of application. However, the technical solution provided by the present invention effectively overcomes this problem by precisely adjusting the contents of the active components vanadium and tungsten. By accurately controlling the ratio of vanadium to tungsten, the active sites remain stable at high temperatures, maintaining good catalytic performance, enabling the overall catalyst to continuously and stably operate under high-temperature conditions above 400°C. This characteristic greatly broadens the applicable scenarios of the catalyst and has extremely high application value for both high-temperature industrial reactions and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a diagram of the catalyst product prepared in Example 1 of the present invention;

[0015] Figure 2 It is a schematic flow chart of the preparation method in Example 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Example 1: A high-temperature denitration catalyst provided by the present invention has the following formula:

[0017] Component Content Ammonium metavanadate Calculated based on the vanadium content, 1% Tungstic acid Calculated based on the tungsten content, 4% Titanium dioxide Calculated based on the titanium element, 50% Carboxymethyl cellulose 20％ Water The balance

[0018] Preparation method: Mix the above components at 2000 r / min for 3 h to obtain a mud material, let the mud material age for 24 h, and then filter the mud material under vacuum conditions to remove impurities and air therein; then extrude the mud material into a shape, with an extrusion pressure of 5 MPa and an extrusion speed of 1.5 m / min to obtain a formed sample. Finally, dry the formed sample. After drying for 10 days, calcine the dried sample at 500°C for 3 hours to finally obtain the catalyst. The integrally formed honeycomb catalyst thus prepared is as Figure 1 shown.

[0019] Example 2: A high-temperature denitration catalyst provided by the present invention has the following formula:

[0020] Component Content Vanadyl oxalate Calculated based on the vanadium content, 3% Sodium tungstate Calculated based on the tungsten content, 10% Zinc titanate Calculated based on the titanium element, 80% Carboxymethyl cellulose 5％ Water The balance

[0021] The preparation method process is as Figure 2 shown: Mix the above components at 5000 r / min for 6 h to obtain a mud material, let the mud material age for 48 h, and then filter the mud material under vacuum conditions to remove impurities and air therein; then extrude the mud material into a shape, with an extrusion pressure of 10 MPa and an extrusion speed of 3 m / min to obtain a formed sample. Finally, dry the formed sample for 20 days, and calcine the dried sample at 650°C for 4 hours to finally obtain the catalyst.

[0022] Example 3: A high-temperature denitration catalyst provided by the present invention has the following formula:

[0023]

[0024]

[0025] Preparation method: Mix the above components at 3500 r / min and stir for 4.5 h to obtain a mud material. Let the mud material age for 36 h, and then filter the mud material under vacuum conditions to remove impurities and air therein. Then extrude the mud material into a shape with an extrusion pressure of 7 MPa and an extrusion speed of 2.5 m / min to obtain a shaped sample. Finally, dry the shaped sample for 15 days and calcine the dried sample at 600 °C for 3.5 hours to finally obtain the catalyst.

[0026] Among the catalyst components provided by the present invention, the titanium-containing support can also be aluminum titanate, titanium silicalite, nitrogen-doped titanium dioxide, barium titanate, and lanthanum titanate. The performance of the obtained catalyst is consistent with that of Examples 1 to 3, so no redundant introduction will be made.

[0027] The following specific experiments are used to illustrate the application of the catalyst provided by the present invention, which can be used as a denitration catalyst for working environments above 400 °C.

[0028] The denitration catalytic efficiency of Examples 1 to 3 of the present invention and the commonly used zeolite-based and noble metal catalysts in the prior art was tested. The test conditions and data are shown in the following table:

[0029] Parameter Test condition Unit Remark Space velocity 10000 <![CDATA[h -1 > / NOx content 800 ppmvd Standard state, dry basis, actual oxygen <![CDATA[SO2 content]]> 20.0 ppmvd Standard state, dry basis, actual oxygen <![CDATA[O2 content]]> 4.00 Dry Vol% Dry basis <![CDATA[H2O content]]> 6.00 ％ / Ammonia-nitrogen molar ratio (denitrification efficiency) 1.00 / / Temperature 200-500 ℃ /

[0030]

[0031]

[0032] It should be noted that the above experimental data are all average values obtained from multiple parallel repeated experiments. When preparing the catalyst of the present invention, the components used, the amounts of the components, and the condition parameters in the preparation method all need to be tested for their catalytic performance after obtaining the finished product in order to obtain the technical solution of the present invention.

[0033] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A high temperature denitration catalyst, characterized in that: The catalyst comprises a vanadium-containing active substance and a tungsten-containing active substance. The content of the vanadium-containing active substance in the catalyst is calculated as vanadium element, and the mass percentage of the vanadium element in the catalyst is 1-3%; the content of the tungsten-containing active substance in the catalyst is calculated as tungsten element, and the mass percentage of the tungsten element in the catalyst is 4-10%.

2. The catalyst according to claim 1, characterized in that The catalyst also includes a titanium-containing carrier. The content of the titanium-containing carrier in the catalyst is calculated as titanium element, and the mass percentage of the titanium element in the catalyst is 50-80%.

3. The catalyst according to claim 1, characterized in that The catalyst also includes a binder, the mass percentage of the binder in the catalyst is 10-20%, and the binder is carboxymethyl cellulose.

4. The catalyst according to claim 1, characterized in that The vanadium-containing active substance is any one of ammonium metavanadate and vanadyl oxalate.

5. The catalyst according to claim 1, characterized in that The tungsten-containing active substance is any one of tungstic acid, sodium tungstate and ammonium metatungstate.

6. The catalyst according to claim 2, characterized in that The titanium-containing carrier is any one of titanium dioxide, zinc titanate, aluminum titanate, titanium silicon molecular sieve, nitrogen-doped titanium dioxide, barium titanate, and lanthanum titanate.

7. A denitration catalyst, characterized in that: The catalyst is an integrally formed honeycomb catalyst.

8. A method for preparing the catalyst according to any one of claims 1 to 7, characterized in that: The carrier, active material and binder are mixed into a slurry, and then aged and extruded to obtain a honeycomb molded sample, and then the molded sample is dried and calcined to obtain a finished catalyst product.

9. The method according to claim 8, characterized in that The carrier, active substance, binder and water are mixed and stirred at 2000-5000 r / min for 3-6 hours to obtain a mud material, and the mud material is aged for 24-48 hours, and then the mud material is filtered under vacuum conditions to remove impurities and air therein; the mud material is then extruded and molded at an extrusion pressure of 5-10 MPa and an extrusion speed of 1.5-3 m / min to obtain a molded sample, and finally the molded sample is dried for 10-20 days, and the dried sample is roasted at 500-650°C for 3-4 hours to finally obtain a catalyst.

10. Use of the catalyst according to any one of claims 1 to 7 and 9, characterized in that: It is used as a denitrification catalyst in an operating environment above 400°C.

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