Overview of denitrification catalysts, what are the high sulfur resistance denitrification catalysts

Most of the SCR denitrification catalysts are composed of two parts: carrier and activity, and the carrier accounts for about 85% of the catalyst composition. In terms of cost, the carrier accounts for about 45% of the total cost of the catalyst

The development of SCR flue gas denitrification catalyst has mainly gone through four stages, the earliest active composition is PT, NH, PD, etc., the reducing agent often uses CO and H2 or hydrocarbons, the active temperature of such catalyst reaction is low, generally below 300 degrees Celsius, at present, there are more catalysts, which are used in the emission control of diesel engines, and then the introduction of metal oxides such as V2O5 and TiO2 as catalysts, 250 degrees to 400 degrees Celsius, It is the active temperature range of metal oxides, among which, the most widely used catalyst in the SCR flue gas denitrification system of coal-fired power plants is titanium-based vanadium catalyst, and the introduction of carbon-based catalyst for desulfurization and denitrification is effectively controlled.

The denitrification catalyst is commonly used as a catalyst for flue gas denitrification with TiO2 as the carrier, V2O5 as the activated active substance, and WO3 as the anti-sintering substance and some inorganic elements.

At present, the most commonly used catalysts are V2O5-WO3 (MoO3) TiO2 series (TiO2 as the main carrier and V2O5 as the main active ingredient).

Flue gas SNCR denitrification process (process diagram).

Flue gas SCR denitrification process (process diagram).

Comparison of different types of denitrification catalysts.

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At present, there are mainly the following types of high-sulfur resistant denitrification catalysts on the market:1V2O5-WO3 TiO2 catalyst:

It is prepared by sol-gel method from tetrabutyl titanate as raw material. The catalyst has excellent denitrification energy and high sulfide resistance CEO2-TIO2-WO3 catalyst: prepared by hydrothermal synthesis or co-precipitation.

The catalyst has good sulfide resistance and can work stably in a high concentration of SO2. 3.Mnox-CEO2 TiO2 catalyst:

Prepared by co-precipitation method. The catalyst has good denitrification energy and high sulfur resistance, and can work stably in a high concentration of SO2 environment. 4.

LAFEO3 catalyst: prepared by solvothermal method. The catalyst has high sulfur resistance and good denitrification energy, and can effectively remove NOx in high concentrations of SO2 and water vapor.

What are the catalysts for high sulfur resistance denitrification?

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At present, there are mainly the following types of high-sulfur resistant denitrification catalysts on the market:1V2O5-WO3 TiO2 catalyst:

It is prepared by sol-gel method from tetrabutyl titanate as raw material. The catalyst has excellent denitrification energy and high sulfide resistance CEO2-TIO2-WO3 catalyst: prepared by hydrothermal synthesis or co-precipitation.

The catalyst has good sulfide resistance and can work stably in a high concentration of SO2. 3.Mnox-CEO2 TiO2 catalyst:

The rebalance is prepared by the co-combustion precipitation method. The catalyst has good denitrification energy and high sulfur resistance, and can work stably in a high concentration of SO2 environment. 4.

LAFEO3 catalyst: prepared by solvothermal method. The catalyst has high sulfur resistance and good denitrification energy, and can effectively remove NOx in high concentrations of SO2 and water vapor.

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Xian Gao Honghua]: Dear, it should be noted that the process conditions and scope of application of different denitrification catalysts are different, so it is necessary to choose according to the actual situation in the specific application of branch potatoes.

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Find the answer for you: high sulfur resistance denitrification catalyst has 1Vanadium-tungsten-titanium catalyst:

It has high catalytic activity and good anti-sulfur performance, and is suitable for denitrification of high-sulfur flue gas. 2.Nickel-chromium catalysts:

It has good sulfur resistance and catalytic activity, and shows good denitrification effect in high sulfur flue gas. 3.Platinum Cobalt Catalyst:

It has high catalytic activity and sulfur resistance, and is suitable for denitrification of high sulfur flue gas. 4.Chromium-molybdenum catalyst:

It has wide and good catalytic activity and sulfur resistance, and is suitable for denitrification of high sulfur flue gas.

Selective catalytic reduction of nitrogen oxides to achieve denitrification.

Selective Catalytic Reduction (SCR) refers to the use of reducing agents (such as NH3, liquid ammonia, urea) to "selectively" react with NOx in flue gas under the action of catalysts to generate non-toxic and non-polluting N2 and H2O. First discovered by Engelhard in the United States and patented in 1957, Japan successfully developed the V2O5 TiO2 catalyst, which is widely used today, and successfully put it into commercial use in oil-fired and coal-fired boilers in 1977 and 1979 respectively. SCR technology has a very significant effect on the control of boiler flue gas NOx, and the technology is relatively mature, and it has become the most widely used and effective flue gas denitrification technology in the world.

Under the reasonable arrangement and temperature range, the removal rate of 80 to 90% can be achieved. In China, the use of SCR for flue gas denitrification has just begun.

Features: In the selective catalytic reduction system, it is generally composed of ammonia storage system, ammonia and air mixing system, ammonia injection system, reactor system and monitoring and control system, etc., for thermal power plants, SCR reactor is generally installed between the boiler economizer and the air preheater, here is a high dust and high temperature arrangement, the flue gas temperature in this interval is conducive to SCR denitrification reduction reaction, and ammonia is sprayed at the appropriate position in the flue between the economizer and the SCR reactor. It is mixed with flue gas and reacted with NOx in the reactor by means of a catalyst. The catalyst is housed in a chamber that resembles a solid reactor.

The catalyst units are usually arranged vertically, and the flue gas flows from top to bottom.

SCR technology has the following characteristics.

High NOx removal efficiency.

According to the relevant literature and the monitoring data of engineering examples, the general NOx removal efficiency of SCR method can be maintained at 70%-90%, and the general NOx outlet concentration can be reduced to about 100mg M, which is an efficient flue gas denitrification technology.

The secondary pollution is small.

The basic principle of the SCR method is to reduce NOx to non-toxic and non-polluting N2 and H2O with a reducing agent, and the secondary pollutant substances produced in the whole process are very few.

The technology is relatively mature and widely used.

SCR flue gas denitrification technology has been widely used in developed countries. For example, in Germany, the SCR method accounts for about 95% of the flue gas denitrification units of thermal power plants. In the flue gas denitrification projects that have been completed or planned in China, the SCR method is mostly used.

The investment cost is high, and the operating cost is high.

Taking China's first thermal power plant with SCR denitrification system - Fujian Zhangzhou Houshi Power Plant as an example, the 600MW unit of the power plant adopts Hitachi's SCR flue gas denitrification technology, with a total investment of about 100 million yuan. In addition to the one-time investment, the operating costs of the SCR process are also high, which is mainly reflected in the high cost of catalyst replacement and the high cost of reducing agent (liquid ammonia, ammonia, urea, etc.).

SCR is a widely used denitrification at present, selective catalytic denitrification, and the raw materials are urea, liquid ammonia, and ammonia.

Is it ammonia? Such a very expensive one seems to be too expensive to produce and should not be used.

Selective Catalytic Reduction (SCR) flue gas denitrification technology is a mature technology with simple operation and control and high denitrification efficiency, which is widely used in flue gas denitrification engineering.

Basic Equation:

4 no + 4 nh3 + o2=4 n2 + 6 h2o

6 NO2 + 8 NH3 = 7 N2 + 12 H2O Under the condition of no catalyst, the chemical reaction temperature of ammonia and nitrogen oxides is 900, and if ammonia is added, part of the ammonia will decompose at high temperature.

If a catalyst is added, the reaction temperature can be reduced to 320-400.

The catalyst is generally a mixture of V2O5 and Woo3 with TiO2 as the matrix.

The specific formula is determined according to the flue gas parameters.

Hope it works for you.

The SCR denitrification system is mainly composed of SCR catalytic reactor, ammonia injection system, flue gas bypass system, ammonia storage and preparation system, etc.

At present, the layout of SCR catalytic reactor generally adopts the high-dust arrangement method at home and abroad, that is, it is arranged in the high-temperature flue between the economizer and the air preheater. At this location, the flue gas temperature reaches the optimal temperature for the reaction. Therefore, the denitrification device of this phase of the project is planned to adopt a high-dust arrangement.

The flue gas is evenly divided into two circuits at the outlet of the boiler economizer, and each flue gas enters a vertically arranged SCR reactor in parallel, that is, each boiler is equipped with two reactors, and the flue gas passes through the homogenizer and enters the catalyst layer. Before the flue gas enters the catalyst layer, there is an ammonia injection system, and the flue gas is fully mixed with ammonia to carry out a catalyst reaction to remove NOx. After the reaction, the flue gas enters the air preheater, electrostatic precipitator, induced draft fan and desulfurization device, and then discharges into the chimney.

The SCR reactor is arranged above the air preheater.

The basic principle of SCR denitrification catalyst is to catalyze the redox reaction between flue gas and ammonia at high temperature under his action, and the process principle is SCR reaction system.

Selective catalytic reduction refers to the use of reducing agents (such as ammonia, liquid ammonia, urea, etc.) to disturb the "selective" reaction with nitrogen oxides in flue gas and generate non-toxic and non-polluting nitrogen and water under the action of catalysts. The method was first discovered and patented by Engelhard in the United States, and later in Japan, driven by the country's environmental policy, the catalytic fibrillator that is now widely used was successfully developed, and successfully put into commercial use in oil-fired and coal-fired boilers in 1977 and 1979, respectively. Selective catalytic reduction (SCR) has a significant effect on the control of nitrogen oxides in boiler flue gas, and the technology is relatively mature, and it has become the most widely used and effective flue gas denitrification technology in the world.

Features: 1. High removal efficiency of nitrogen-containing chemicals;

2. Small secondary pollution;

3. The technology is relatively mature;

4. High investment costs and high operating costs.