CN104437529A - SCR catalyst for efficiently oxidizing elemental mercury and preparation method of SCR catalyst - Google Patents

Abstract

The invention discloses an SCR catalyst for efficiently oxidizing elemental mercury and a preparation method thereof, wherein the catalyst consists of three parts: an active component, an auxiliary agent and a carrier, and the active component is a mixture of CuCl ₂ and V ₂ O ₅ , the auxiliary agent is WO ₃ , the carrier is: TiO ₂ ; the mass of the catalyst is based on the mass of the carrier, and the mass of the active component and the auxiliary agent account for 1%-10% and 1%-8% of the mass of the carrier respectively; In , the mass ratio of CuCl ₂ to V ₂ O ₅ is 1-10:10. The benefit of the present invention is that: the SCR catalyst of the present invention is less dependent on the Cl content in the flue gas, and can efficiently oxidize elemental mercury while ensuring high denitrification efficiency; the two active components CuCl ₂ and V ₂ The effective ratio of O ₅ greatly improves the catalytic oxidation efficiency of the catalyst to elemental mercury; the preparation method of the SCR catalyst of the present invention adopts the impregnation method, and the steps are simple, the reaction process is easy to control, and the stability is good.

Description

SCR catalyst for efficient oxidation of elemental mercury and preparation method thereof

technical field

The invention relates to a catalyst and a preparation method thereof, in particular to an SCR catalyst for efficiently oxidizing elemental mercury and a preparation method thereof, belonging to the technical field of catalysts.

Background technique

Mercury is a global pollutant that travels through the atmosphere and is very mobile. After deposition, it is further converted into methylmercury, thereby causing harm to human health and the environment.

Combustion of fossil fuels is the largest source of mercury emissions from human activities. According to statistics, the coal-fired power plants in the United States currently emit 48 tons of mercury per year, accounting for one-third of the total amount of mercury emitted by human activities; the Pollution Prevention Department of the Ministry of Environmental Protection of my country has conducted research on the mercury emission inventory and mercury reduction of major mercury-related industries. The report shows that in 2007 my country's thermal power mercury emissions were 138.5 tons. Based on the technical route of collaborative control, the compilation team calculated that the thermal power mercury production in 2007 was 205 tons. According to the current installed capacity development trend, by 2010, the thermal power Production was 257 tonnes, 359 tonnes in 2015 and 431 tonnes in 2020.

Therefore, taking measures to control mercury produced by coal combustion has become the focus of attention of various countries. In February 2009, the Executive Council of the United Nations Environment Program agreed to establish a binding mechanism. Due to the considerable amount of mercury discharged into the environment in China, the State Council attaches great importance to the prevention and control of mercury pollution. In the "Notice of the General Office of the State Council Forwarding the Guiding Opinions of the Ministry of Environmental Protection and Other Departments on Strengthening the Prevention and Control of Heavy Metal Pollution" issued in 2009, the prevention and control of mercury pollution was listed as the focus of work. In 2011, the "Twelfth Five-Year Plan for Comprehensive Prevention and Control of Heavy Metal Pollution" approved by the State Council and the "Twelfth Five-Year Plan for Joint Prevention and Control of Air Pollution in Key Areas" under preparation, both control atmospheric mercury emissions from coal-fired power plants. arrange. It clearly stated: "Deeply carry out work on atmospheric mercury emissions from coal-fired power plants, actively promote coordinated control of mercury pollution, compile lists of atmospheric mercury emissions from key industries such as coal-fired, non-ferrous metals, cement, and waste incineration, and study and formulate control measures." In order to control the emission of mercury from thermal power plants and support the implementation of the Convention, the "Emission Standards of Air Pollutants from Thermal Power Plants" promulgated in July 2011 increased the emission limit of mercury to 0.03mg/m ³ , starting from January 1, 2015 implement.

There are three main forms of mercury in coal-fired flue gas, namely elemental mercury (Hg ⁰ ), divalent mercury (Hg ²⁺ , including compounds such as mercury oxide HgO and mercury chloride HgCl ₂ ), and particulate mercury (Hg ^P ). Hg ^P is adsorbed in the fly ash and dust in the flue gas, and can be removed by dust removal equipment (electrostatic precipitator ESP and filter dust collector FF). Hg ²⁺ is easily soluble in water and can be removed by wet absorption. Atomic Hg ⁰ is insoluble in water, volatile, and exists in the flue gas in the form of gas. It is difficult to capture directly by dust removal and wet absorption equipment, and can be almost completely discharged into the atmosphere with the flue gas. Therefore, for mercury removal from coal-fired flue gas, the difficulty is to solve the problem of Hg ⁰ removal.

At present, the researched mercury removal methods mainly focus on two aspects, one is the sorbent injection technology (Sorbent Injection), which uses the sorbent to adsorb the mercury in the flue gas on the sorbent, and then collects the sorbent through dust removal and other equipment , such as spraying activated carbon powder, fly ash powder and calcium-based compound powder into the flue gas to achieve the purpose of mercury removal; on the other hand, the use of existing air pollution control devices (mainly including dust collectors, Denitrification device and desulfurization device) based simultaneous mercury removal method (Co-benefit Mercury Removal). Although the sorbent injection technology has high mercury removal efficiency, its cost is very high. For example, the cost of mercury removal by injecting activated carbon sorbent into the flue is about 80,000-100,000 US dollars/kg. In addition, the follow-up treatment of the sorbent is difficult. If it is not handled properly, it will easily cause secondary pollution. The method of mercury removal using existing pollution control devices has a relatively large advantage in this regard. More than 95% of my country's coal-fired power plants install electrostatic precipitators (ESP) as the main air pollution control equipment, and a small amount of bag dust collectors are used to control the emission of particulate matter. In recent years, almost all power plants have installed flue gas desulfurization equipment (FGD), mainly wet desulfurization equipment (WFGD). More and more power plants have installed or plan to install flue gas denitrification equipment, mainly selective catalytic reduction (SCR) technology. The application of these air pollution control equipment in power plants will not only control NOx, SOx, and particulate matter emissions, but also change the conversion law of mercury in flue gas and the emission characteristics of mercury in power plants to varying degrees.

Field test data from the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE) show that for power plants installed with electric precipitators (ESP) and WFGD (this is also a typical air pollution control device installed in power plants in China), according to the type of coal fired Different, the removal efficiency of mercury is in the range of 0%-74%. The main reason for the low removal efficiency is that WFGD can only remove Hg ²⁺ which is easily soluble in water, but not Hg in flue gas. ⁰ .

The SCR denitrification device converts NOx in the flue gas into N ₂ and H ₂ O by adding NH ₃ under the action of the reaction temperature above 350°C and the SCR denitrification catalyst, so as to remove the NOx in the flue gas. In this process, the SCR denitration catalyst also participates in the oxidation reaction of mercury. Under the action of the SCR denitration catalyst, the elemental mercury reacts with Cl ₂ and O ₂ in the flue gas to form Hg ²⁺ , which reduces the content of Hg ⁰ . The content of Hg ²⁺ rises. The SCR denitrification system does not remove Hg, but its main function is to oxidize Hg ⁰ in the flue gas to Hg ²⁺ and increase the proportion of Hg ²⁺ in the flue gas. The potential ability of SCR catalysts to catalyze the oxidation of elemental mercury makes it possible to use the existing pollutant control equipment in coal-fired power plants to control the emission of mercury pollution in flue gas, and use SCR denitrification devices to realize the form conversion of Hg ⁰ to Hg ²⁺ , and then Use subsequent WFGD desulfurization equipment to wash and remove Hg ²⁺ . Utilizing existing pollutant control equipment in coal-fired power stations to control coal-fired flue gas mercury emissions without adding additional control equipment is a low-cost control technology. However, the key to this technology is how to maximize the use of SCR catalysts before WFGD imports To a certain extent, the form transformation of Hg ⁰ to Hg ²⁺ is realized.

Vanadium-based SCR catalyst (V ₂ O ₅ -WO ₃ /TiO ₂ ) is currently the most widely used SCR denitration catalyst, in which V ₂ O ₅ is the active center of the catalytic reaction, which has high efficiency and good anti-poisoning performance. The catalytic oxidation efficiency of vanadium-based SCR catalysts to Hg0 is limited by various conditions and has great fluctuations. For example, the type of coal, the amount of ammonia injection and the content of HCl will all affect the efficiency of SCR to catalyze the oxidation of elemental mercury.

A large number of studies have shown that the content of chlorine in coal has a great influence on the change of mercury form after the flue gas passes through the SCR system, and the higher the chlorine content in coal, the higher the concentration of divalent mercury at the SCR outlet, which is more conducive to the downstream humidity. The removal of mercury by FGD system. Field test data show that in a power plant burning high Cl bituminous coal, the mercury oxidation efficiency of the SCR device can be as high as 90%; while in a power plant burning subbituminous coal with low Cl, the oxidation efficiency of mercury in the SCR device is lower than 30% .

In view of the generally low Cl content in coal in my country, the present invention aims to find a mercury removal catalyst with low dependence on Cl content in flue gas.

Contents of the invention

The object of the present invention is to provide an SCR catalyst which is less dependent on Cl content in the flue gas and can efficiently oxidize elemental mercury while ensuring high denitrification efficiency, and a preparation method of the catalyst.

In order to achieve the above object, the present invention adopts the following technical solutions:

An SCR catalyst for efficiently oxidizing elemental mercury is characterized in that it consists of three parts: an active component, an auxiliary agent and a carrier, wherein:

The aforementioned active components are: a mixture of CuCl ₂ and V ₂ O ₅ ;

The aforementioned additives are: WO ₃ ;

The aforementioned carrier is: TiO ₂ .

The aforementioned SCR catalyst for efficient oxidation of elemental mercury is characterized in that the quality of the catalyst is based on the mass of the carrier, the mass of the active component accounts for 1%-10% of the mass of the carrier, and the mass of the auxiliary agent accounts for 1%-10% of the mass of the carrier. 8%.

The aforementioned SCR catalyst for efficient oxidation of elemental mercury is characterized in that, in the aforementioned active components, the mass ratio of CuCl ₂ to V ₂ O ₅ is 1-10:10.

The aforementioned SCR catalyst for efficient oxidation of elemental mercury is characterized in that the preparation process is as follows:

(1), ammonium paratungstate and ammonium metavanadate are dissolved in oxalic acid solution, heated and stirred to obtain ammonium paratungstate and ammonium metavanadate mixed solution;

(2), adding titanium dioxide powder into the mixed solution obtained in step (1), after fully stirring, ultrasonically impregnating for 1-3 hours;

(3), the impregnation product obtained in step (2) is placed in a drying oven to dry, then placed in a muffle furnace for roasting, ground after roasting, and passed through an 80-mesh sieve;

(4), the calcined product obtained in step (3) is placed in CuCl ₂ solution, after fully stirring, ultrasonic impregnation for 1-3 hours;

(5), the impregnated product obtained in step (4) is placed in a drying box to dry again, and then placed in a muffle furnace to roast again;

(6) Grinding and sieving the calcined product obtained in step (5), and taking the 40-60 mesh part, which is the required catalyst.

The aforementioned SCR catalyst for efficiently oxidizing elemental mercury is characterized in that, in step (3) and step (5), the temperature of the drying oven is 100-120° C., and the drying time is 1-2 hours.

The aforementioned SCR catalyst for highly efficient oxidation of elemental mercury is characterized in that in step (3) and step (5), the calcination temperature is 400-650° C., and the calcination time is 2-4 hours.

The benefits of the present invention are:

1. The SCR catalyst of the present invention is less dependent on Cl content in flue gas, and can efficiently oxidize elemental mercury while ensuring high denitrification efficiency;

2. The effective ratio of the two active components CuCl ₂ and V ₂ O ₅ greatly improves the catalytic oxidation efficiency of the catalyst to elemental mercury;

3. The preparation method of the SCR catalyst of the present invention adopts the impregnation method, the steps are simple, the reaction process is easy to control, and the stability is good;

4. The catalyst prepared by the impregnation method of the present invention has the characteristics of large temperature window, high activity, and weak dependence on HCl.

Detailed ways

The present invention will be specifically introduced below in conjunction with specific embodiments.

First, the catalyst of the present invention is introduced.

The catalyst of the present invention consists of three parts: active component, auxiliary agent and carrier, wherein the active component is a mixture of CuCl ₂ and V ₂ O ₅ , the auxiliary agent is WO ₃ , and the carrier is TiO ₂ . The mass of the catalyst is based on the mass of the carrier, the mass of the active component accounts for 1%-10% of the mass of the carrier, and the mass of the auxiliary agent accounts for 1-8% of the mass of the carrier. In the active components, the mass ratio of CuCl ₂ to V ₂ O ₅ is 1-10:10.

The catalyst of the present invention is used to control the emission of nitrogen oxides and elemental mercury in the flue gas of coal-fired boilers, specifically to oxidize elemental mercury into divalent mercury without adding other mercury removal equipment, and the existing pollutant control equipment can be used to complete the removal of mercury. HG. Its catalytic principle is as follows:

During the catalytic oxidation reaction, Hg ⁰ in the flue gas is adsorbed on the surface of the catalyst and reacts with the Cl atoms in CuCl ₂ to form HgCl ₂ , while CuCl ₂ is reduced to CuCl at the same time. The CuCl produced by the reaction reacts with HCl and O ₂ in the flue gas, passes through the intermediate product Cu ₂ OCl ₂ , and finally oxidizes to CuCl ₂ . During the whole reaction process, _CuCl2 acts as a catalyst, and the reaction formula is as follows:

Hg(0)+2CuCl ₂ →HgCl ₂ +2CuCl

Cu ₂ OCl ₂ +2HCl→2CuCl ₂ +H ₂ O

The overall reaction formula:

Next, the preparation method of the catalyst of the present invention is introduced.

When preparing the catalyst of the present invention, ammonium paratungstate is used as the precursor of WO ₃ , and ammonium metavanadate is used as the precursor of V ₂ O ₅ .

Example 1

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.3459 g of ammonium paratungstate and 0.0763 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.0274g CuCl ₂ and dissolve it in 10ml deionized water, place the calcined product obtained in step (3) in the CuCl ₂ solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 1wt% V ₂ O ₅ -5wt% WO ₃ -0.5wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 79%.

Example 2

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.3459 g of ammonium paratungstate and 0.0763 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.0411g of _CuCl2 and dissolve it in 10ml of deionized water, place the calcined product obtained in step (3) in the _CuCl2 solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 1wt% V ₂ O ₅ -5wt% WO ₃ -0.75wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 87%.

Example 3

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.3459 g of ammonium paratungstate and 0.0763 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.0548g of _CuCl2 and dissolve it in 10ml of deionized water, place the calcined product obtained in step (3) in the _CuCl2 solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 1wt% V ₂ O ₅ -5wt% WO ₃ -1wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500 mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 98%.

Example 4

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.3459 g of ammonium paratungstate and 0.0763 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.0055g CuCl ₂ and dissolve it in 10ml deionized water, place the calcined product obtained in step (3) in the CuCl ₂ solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 1wt% V ₂ O ₅ -5wt% WO ₃ -0.1wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500 mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 68%.

Example 5

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.0692 g of ammonium paratungstate and 0.3052 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.0548g of _CuCl2 and dissolve it in 10ml of deionized water, place the calcined product obtained in step (3) in the _CuCl2 solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 4wt% V ₂ O ₅ - 1wt% WO ₃ - 1wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 88%.

Example 6

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.5534 g of ammonium paratungstate and 0.5341 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven at 100° C. for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550° C. for 3 hours, grind it, and pass through an 80-mesh sieve.

(4) Weigh 0.1644g CuCl ₂ and dissolve it in 10ml deionized water, place the calcined product obtained in step (3) in the CuCl ₂ solution, stir thoroughly, and ultrasonically impregnate for 2 hours.

(5) Place the impregnated product obtained in step (4) in a drying oven to dry at 100°C for 2 hours, and then place it in a muffle furnace for calcination at a temperature of 550°C for 4 hours.

(6) Grind and sieve the calcined product obtained in step (5), and take the 40-60 mesh part, which is the required catalyst.

In the catalyst, the mass content of each component is: 7wt% V ₂ O ₅ -8wt% WO ₃ -3wt% CuCl ₂ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500 mg. It is measured that the oxidation efficiency of the catalyst to elemental mercury is 74%.

Example 7

(1) Dissolve 1 g of oxalic acid in 20 ml of deionized water, weigh 0.3459 g of ammonium paratungstate and 0.0763 g of ammonium metavanadate and dissolve them in the oxalic acid solution, heat and stir to obtain a solution of ammonium paratungstate and ammonium metavanadate.

(2) Add 5 g of titanium dioxide powder into the mixed solution obtained in step (1), stir thoroughly, and ultrasonically impregnate for 2 hours.

(3) Place the impregnated product obtained in step (2) in a drying oven and dry at 100°C for 2 hours, then place it in a muffle furnace for roasting at a temperature of 550°C for 4 hours, grind it, and pass through a 40-60 mesh sieve , the resulting part is the desired catalyst.

In the catalyst, the mass content of each component is: 1wt% V ₂ O ₅ -5wt% WO ₃ /TiO ₂ .

The catalyst was placed in a fixed-bed reactor to conduct a simulation experiment of mercury removal efficiency. The simulated flue gas is 6% oxygen, 12% carbon dioxide, 600ppm sulfur dioxide, 200ppm nitric oxide, 200ppm ammonia, 15μg/ ^m3 Hg ⁰ , nitrogen is the balance gas, the total gas flow rate is 15L/min, and the reaction temperature is 350 degrees Celsius , the catalyst loading was 500mg. The oxidation efficiency of the catalyst to elemental mercury was measured to be 7%.

As can be seen from Examples 1-6: after adding CuCl _active ingredient in the catalyst, the catalyst is placed in a fixed-bed reactor to carry out a mercury removal efficiency simulation experiment, and the experimental results show that the catalyst is 1% of the mass of the carrier when the mass of the active component accounts for 1% of the mass of the carrier. Under the condition that -10% and the mass of the additive accounts for 1%-8% of the mass of the carrier, the catalytic oxidation efficiency of the catalyst for elemental mercury in flue gas reaches 68%-98%.

Visible by embodiment 7: do not add _CuCl catalyzer of active ingredient, this catalyst is placed in fixed-bed reactor and carries out mercury removal efficiency simulation experiment, and experimental result shows that catalyst accounts for 1% of carrier mass in active component mass, auxiliary agent Under the condition that the mass accounts for 5% of the mass of the carrier, the catalytic oxidation efficiency of the catalyst for elemental mercury in the flue gas is 7%, which is much lower than that of the catalyst added with _CuCl2 active component.

It should be noted that the above embodiments do not limit the present invention in any form, and all technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims (6)

1., for the SCR catalyst of efficient oxidation Elemental Mercury, it is characterized in that, by active component, auxiliary agent and carrier three part form, wherein:

Described active component is: CuCl ₂and V ₂o ₅mixture;

Described auxiliary agent is: WO ₃;

Described carrier is: TiO ₂.

2. the SCR catalyst for efficient oxidation Elemental Mercury according to claim 1, is characterized in that, catalyst quality take carrier quality as benchmark, and the quality of active component accounts for the 1%-10% of carrier quality, and the quality of auxiliary agent accounts for the 1%-8% of carrier quality.

3. the SCR catalyst for efficient oxidation Elemental Mercury according to claim 1 and 2, is characterized in that, in described active component, and CuCl ₂with V ₂o ₅mass ratio be 1-10:10.

4. the SCR catalyst for efficient oxidation Elemental Mercury according to claim 1,2 or 3, it is characterized in that, preparation process is as follows:

(1), ammonium paratungstate and ammonium metavanadate are dissolved in oxalic acid solution, add thermal agitation, obtain ammonium paratungstate and ammonium metavanadate mixed solution;

(2), by titania powder join in the mixed solution of step (1) gained, after fully stirring, ultrasonic immersing 1-3 hour;

(3), by the impregnation product of step (2) gained be placed in drying box dry, be then placed in Muffle furnace roasting, grind after roasting, cross 80 mesh sieves;

(4), the calcined product of step (3) gained is placed in CuCl ₂in solution, after fully stirring, ultrasonic immersing 1-3 hour;

(5), by the impregnation product of step (4) gained be placed in drying box again dry, be then placed in Muffle furnace roasting again;

(6), the calcined product of step (5) gained is carried out grinding sieve, get 40-60 object part, namely required catalyst.

5. the SCR catalyst for efficient oxidation Elemental Mercury according to claim 4, is characterized in that, in step (3) and step (5), the temperature of drying box is 100-120 DEG C, and drying time is 1-2 hour.

6. the SCR catalyst for efficient oxidation Elemental Mercury according to claim 4 or 5, is characterized in that, in step (3) and step (5), sintering temperature is 400-650 DEG C, and roasting time is 2-4 hour.