CN106076417A - Charcoal base heteropolyacid catalyst and preparation and application method thereof for low-temperature flue gas simultaneous SO_2 and NO removal - Google Patents

Abstract

The invention discloses a carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas and its preparation and application method. The catalyst uses activated carbon as a carrier and Keggin type heteropolyacid as an active component. The content in parts by weight is: 80-85 parts by weight of activated carbon, and 15-20 parts by weight of Keggin type heteropolyacid. The catalyst provided by the present invention is not highly dependent on temperature, and still has high desulfurization and denitrification activity under low temperature conditions (80-160°C); therefore, the catalyst can be placed at the tail of the lower-temperature flue gas treatment system, where After the dust removal system, the dust is greatly reduced, and the content of alkali metal and alkaline earth metal attached to the dust is also reduced, so that the blocking effect of dust on the catalyst and the poisoning effect of alkali metal on the catalyst are also greatly reduced, reducing the consumption of catalyst during operation. The service life of the catalyst is extended; for the user, it can reduce the number of maintenance times and costs in the later period.

Description

Carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas and its preparation and application application method

technical field

The invention relates to the field of catalytic flue gas desulfurization and denitrification, in particular to a catalyst capable of simultaneously desulfurizing and denitrifying low-temperature flue gas and a preparation method thereof.

Background technique

my country's air pollution is very serious, among which sulfur dioxide and nitrogen oxides are the main air pollutants in our country, and they are also the focus and difficulty of air pollution control and environmental protection. According to the China Environmental Status Bulletin, the total emissions of SO ₂ and nitrogen oxides in the atmosphere in China in 2014 were 19.744 million tons and 20.788 million tons, respectively. Since the "Tenth Five-Year Plan", with the construction of desulfurization facilities in my country's power plants, the effect of sulfur dioxide control has begun to appear, and nitrogen oxides have begun to replace sulfur dioxide as the largest acid polluting gas. Therefore, how to remove nitrogen oxides in flue gas desulfurization has become an urgent problem to be solved in my country's air pollution control.

Flue gas desulfurization technologies are mainly divided into two categories: wet desulfurization and dry desulfurization. The main method of so-called wet desulfurization is to spray lime slurry and react with sulfur dioxide in the flue gas to form slurry-like calcium sulfate gypsum. However, this method has the disadvantages of large investment, high operating cost, and secondary pollution. The so-called dry flue gas desulfurization is the application of powdery or granular absorbents, adsorbents or catalysts to remove SO ₂ in the flue gas. The advantage is that the process is simple, there is no problem of sewage and acid treatment, low energy consumption, no "white smoke" phenomenon, the purified flue gas does not need secondary heating, and is less corrosive. The disadvantage is that the desulfurization efficiency is low, the equipment is huge, the investment is large, the floor area is large, and the operation technology requirements are high.

Flue gas denitrification technology is currently widely used in industry is selective catalytic reduction technology (SCR) and selective non-catalytic reduction (SNCR) technology. Among them, SCR is the most mainstream flue gas denitrification technology in the world. This technology is a catalytic reaction process in which the reducing agent preferentially reacts with nitrogen oxides to generate nitrogen and water under the action of a catalyst in an oxygen-containing atmosphere. Among them, the gases used as reducing agents mainly include NH ₃ , CO, and hydrocarbons.

At present, the desulfurization and denitrification process widely used in industrial flue gas in China is the combination of traditional desulfurization technology (FGD) combined with selective catalytic reduction technology (SCR) to remove SO ₂ and nitrogen oxides in flue gas, such as lime/limestone Method - SCR method combined process. The combined desulfurization and denitrification process generally has a high pollutant removal efficiency, but because two sets of devices are used to perform desulfurization and denitrification separately, there are disadvantages such as large footprint, complicated process, and high investment and operating costs.

Therefore, the desulfurization and denitrification technology that simultaneously removes SO2 and nitrogen oxides in flue gas in one system undoubtedly has greater advantages _over it. In recent years, flue gas simultaneous desulfurization and denitrification technologies have gradually begun to attract people's attention, including: plasma method, liquid absorption method and adsorption catalytic method. However, many technologies of the plasma method rely on foreign imports, and it is difficult to realize industrial application in my country. The liquid absorption method has disadvantages such as easy corrosion of equipment, high cost of absorption liquid, and easy to cause secondary pollution. The adsorption catalytic method overcomes the above shortcomings, and is currently the most promising technology for simultaneous desulfurization and denitrification of flue gas.

The Chinese patent document with the publication number CN102974359A discloses a catalyst for simultaneous desulfurization and denitrification. The catalyst uses activated carbon (AC) as a carrier, neodymium trioxide as an active component, and cobalt monoxide as a promoter. The mass fraction of the catalyst is 60-98 parts by weight of AC, 2-40 parts by weight of Nd ₂ O ₃ , and 0-20 parts by weight of cobalt monoxide. The preparation method is to prepare neodymium salt and cobalt salt solution first, add polyvinyl alcohol to it, stir to dissolve, then add activated carbon particles or powder, then heat and evaporate to an appropriate amount of water, and use different molding methods to make particles, columns or honeycombs Catalyst, finally the shaped catalyst is dried, and the finished catalyst is obtained by calcining at different temperature ranges.

Although the catalyst has high catalytic activity, neodymium is a rare earth metal, which is expensive and is listed in the list of hazardous chemicals; the preparation method is complicated, the catalyst components are many, the technical requirements are high, and the preparation cost is high. Therefore, it is difficult to realize industrial application and popularization; and the reaction temperature is high, only under the condition of 350-500 ℃ can the removal rate of SO2 and nitrogen _oxide be higher, so it must be arranged in the high-temperature and high-dust section, which will easily cause the poisoning and loss of catalyst live.

Contents of the invention

In view of the current situation and shortcomings of flue gas desulfurization and denitrification technology in the prior art, the first object of the present invention is to provide a high-activity, low-cost, green and environmentally friendly carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas; The second object of the present invention provides a method for preparing the carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas; based heteropolyacid catalyst method.

For the first purpose of the present invention, the carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas provided by the present invention uses Keggin type heteropolyacid as the active component and activated carbon as the carrier. Keggin-type heteropolyacids have strong proton and electron transmission and storage capabilities, large molecular volume, strong redox and strong acidity, and are widely used in the field of catalysis. However, it has problems such as poor thermal stability, small specific surface area, and easy dissolution in the liquid phase, which limits its development in the field of catalysis. The invention loads the heteropolyacid on the activated carbon carrier, utilizes the high specific surface area, rich pore structure and good chemical stability of the activated carbon to overcome the above disadvantages and achieve a stable catalytic effect.

The parts by weight of each component in the carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of low-temperature flue gas are: 80-85 parts by weight of activated carbon, and 15-20 parts by weight of Keggin type heteropolyacid. When the Keggin type heteropolyacid content is less than 15 parts by weight, the active component is insufficient, which will directly affect the desulfurization and denitrification efficiency; Covering, blocking, and reducing the specific surface area of the surface pores, on the contrary, make the desulfurization and denitrification efficiency of the catalyst worse.

The present invention further provides a method for preparing the above-mentioned carbon-based heteropolyacid catalyst for simultaneous desulfurization and denitrification of flue gas, comprising the following preparation process steps:

(1) Under the condition of 60-65°C, the activated carbon particles are pickled with a nitric acid solution with a mass fraction of 28%-32%, then washed with water until neutral, and dried (denoted as NAC);

(2) Weigh 15-20 parts by weight of heteropoly acid, dissolve it in water to make a heteropoly acid solution with a mass fraction of 8.9%-12.0%; then weigh 80-85 parts by weight of NAC, and soak it in the above-mentioned mass fraction 8.9% to 12% heteropolyacid solution, standing still for no less than 18 hours, evaporating to dryness at 60-65°C; then drying at 100-105°C for 10-12h to obtain a catalyst precursor;

(3) With N ₂ as the protective gas, the catalyst precursor is placed in a muffle furnace for calcination, the heating rate is 4-6°C/min, the calcination temperature is 200-800°C, and the calcination time is 2-3h. Then cool naturally to room temperature to obtain the finished catalyst.

The above step (1) is to carry out conventional pickling treatment on the activated carbon, and the particle size of the activated carbon used is between 10 and 20 mesh. Before pickling the activated carbon, it needs to be pretreated, that is, the activated carbon is immersed in distilled water and boiled for 1-2 hours, and then dried at 100-105°C for 10-12 hours; after the pretreatment, the activated carbon is then acid-washed. , that is, the activated carbon is immersed in a nitric acid solution with a mass fraction of 28% to 32%, and kept at 60 to 65°C for 1 to 2 hours, then the acid solution is filtered off, and the deionized water is used for suction filtration and washing until the pH is 6-7 Finally, dry at 100-105°C for 10-12 hours to obtain NAC.

The purpose of the above step (2) is to prepare the catalyst precursor, which adopts the equal-volume impregnation method, that is, the volume of the prepared heteropolyacid solution is the same as the volume of the added activated carbon. By impregnating the activated carbon in the heteropoly acid solution for a long time, combined with the rich pore structure of the activated carbon, the heteropoly acid is evenly loaded on the activated carbon.

The purpose of the above step (3) is to activate the catalyst, and it is necessary to control the calcination temperature at 200-800°C. It has been found through research that when the calcination temperature is too low, the effective desulfurization time of the catalyst will be shortened; and when the calcination temperature is too high, The denitrification efficiency of the catalyst will decrease; when the roasting temperature is controlled at 300-500°C, the carbon-based heteropolyacid catalyst provided by the invention has high desulfurization and denitrification activity at low temperature, especially the carbon-based phosphotungstic acid catalyst, desulfurization The efficiency can reach more than 98%, and the denitrification efficiency can be as high as 82.8%. In addition, the catalyst obtained in this step has good thermal stability and is not easy to decompose under low temperature conditions (80-160° C.).

Heteropolyacids are oxygen-containing polyacids that are bridged by heteroatoms and polyatoms through oxygen atoms in a certain structure. The inventors have realized that heteropolyacids have large molecular volumes and excellent transport of electrons and protons. and storage capacity, the activity of "lattice oxygen", high proton acidity, and the characteristics of easy separation, non-toxic, odorless, and non-volatile. Based on the above characteristics, heteropolyacids are used to prepare catalysts for flue gas desulfurization and denitrification , for flue gas desulfurization and denitrification.

The catalyst provided by the invention can be used as a catalyst for flue gas desulfurization and denitrification simultaneously, and its desulfurization and denitrification mechanism is as follows:

(1) Desulfurization mechanism, SO ₂ is firstly adsorbed on the surface of the catalyst, under the catalysis of the active component heteropolyacid, SO ₂ is oxidized to SO ₃ , and at the same time SO ₃ reacts with water vapor in the flue gas to generate sulfuric acid; The sulfuric acid attached to the surface of the catalyst affects the activity of the catalyst, so the catalyst needs to be desulfurized and regenerated to obtain sulfuric acid and a catalyst that restores its activity.

(2) Denitrification mechanism, when the flue gas is in contact with the catalyst, the _NOx (x=1 or 2) in it will undergo a reduction reaction with _NH3 under the action of the active component heteropolyacid to generate non-toxic and polluting _N2 and water; the main reactions are as follows:

Due to the strong proton acidity of the heteropoly acid, the basic gas _NH3 is easy to undergo adsorption reaction with it, which enhances the contact between the reactant and the catalyst, which is conducive to the occurrence of subsequent chemical reactions, thereby improving the denitrification efficiency.

The beneficial effects of the present invention are:

(1) The activated carbon required by the present invention has a wide range of sources, easy access, and simple preparation method; the preparation cost is cheap and suitable for large-scale production; after accounting, compared with the simultaneous desulfurization and denitrification catalyst disclosed in the Chinese patent literature with the publication number CN102974359A, the present invention The preparation cost of the provided catalyst can be reduced by about 110 yuan/Kg;

(2) The catalyst provided by the present invention is not highly dependent on temperature, and still has high desulfurization and denitrification activity under low temperature conditions (80-160°C); therefore, the catalyst can be placed at the tail of the lower-temperature flue gas treatment system , here is located after the dust removal system, the dust is greatly reduced, and the content of alkali metals and alkaline earth metals attached to the dust is also reduced, so that the blocking effect of dust on the catalyst and the poisoning effect of alkali metals on the catalyst are also greatly reduced, reducing the catalyst during operation. The consumption of the catalyst prolongs the service life of the catalyst; for the user, it can reduce the maintenance times and operating costs in the later period.

Description of drawings

Fig. 1 is a desulfurization simulation test using the catalysts obtained in Example 5, Example 6 and Example 7 of the present invention, and the desulfurization efficiency is a curve diagram of the desulfurization reaction time;

Fig. 2 is a denitrification simulation test using the catalysts obtained in Example 1, Example 2 and Example 3 of the present invention, and a graph showing the variation of denitrification efficiency with the denitrification reaction temperature.

detailed description

The present invention will be further described below through the accompanying drawings and specific embodiments, the purpose of which is to enable those skilled in the art to better understand the content of the present invention, rather than to limit the content of the present invention.

In order to study the desulfurization and denitrification performance of the carbon _- based heteropolyacid catalyst provided by the present invention, the catalyst prepared in the following examples is prepared to remove SO2 and the performance of NO in the simulated flue gas is tested, and the test conditions are: simulated flue gas with The flow rate is 945mL/min through the simulated reactor, the inlet concentration of SO ₂ in the simulated flue gas is 1000ppm, the concentration of NO is 500ppm, the oxygen content is 10%, the balance gas is nitrogen, and the space velocity is 5000h ^-1 ; the front end of the simulated reactor is desulfurized, The back end of the simulated reactor is fed with ammonia gas at the NH ₃ /NO volume ratio of 1:1 for destocking; the temperature of the simulated reactor is controlled at 60°C to 200°C.

Example 1

Weigh 8g of commercial activated carbon, immerse it in distilled water and boil for 2h, then place it in a constant temperature drying oven at 105°C for 12h; then immerse it in a nitric acid solution with a mass fraction of 30%, and keep it in a constant temperature water bath at 60°C for 2h ; Filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 105°C for 12 hours.

Weigh 2g of phosphomolybdic acid and dissolve it in 16mL of water. Add the above-mentioned activated carbon into the aqueous solution of phosphomolybdic acid, stir manually until the mixture is even, seal it and let it stand for 18 hours, keep stirring in the water bath in a constant temperature water bath at 60°C until it evaporates to dryness, and then dry it in a constant temperature drying oven at 100°C for 12 hours to obtain the catalyst Precursor. Put the above precursor in a muffle furnace for activation, use N ₂ as the protective gas, the gas flow rate is 200ml/min, the heating rate is 5°C/min, when the temperature rises to 200°C, stay for 2h. Cool naturally to room temperature to obtain a carbon-based phosphomolybdic acidifying agent with a loading of 20%.

The results of desulfurization and denitrification experiments show that the desulfurization efficiency of the catalyst can be maintained above 95% at a reaction temperature of 60-140°C, but cannot reach 100%. When the reaction temperature exceeds 140°C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst first increases and then decreases with the increase of temperature, and is the best at 140°C, reaching 66.2% (see Figure 2).

Example 2

Weigh 8g of commercial activated carbon, immerse it in distilled water and boil for 1.5h, then place it in a constant temperature drying oven at 100°C for 12h; then immerse it in a nitric acid solution with a mass fraction of 28%, and keep it 1h; filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 100°C for 12h.

Weigh 2g of silicotungstic acid and dissolve it in 16mL of water. Add the treated activated carbon into the aqueous solution of silicotungstic acid, stir manually until the mixture is uniform, seal and let stand for 21 hours. The impregnated activated carbon was placed in a constant temperature water bath at 63°C and stirred continuously until evaporated to dryness, and then dried in a constant temperature drying oven at 102°C for 11 hours to obtain a catalyst precursor.

Put the above precursor in a muffle furnace for roasting activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 5°C/min, when the temperature rises to 300 After ℃, stay for 2.5h. Cool naturally to room temperature to obtain a carbon-based silicotungstic acid catalyst with a loading capacity of 20%.

The results of desulfurization and denitrification experiments show that: at a reaction temperature of 80-140°C, the desulfurization efficiency of the catalyst is relatively high and can basically be maintained above 98%. When it reaches 160°C, the desulfurization efficiency begins to decline. The denitrification efficiency showed a trend of first increasing and then decreasing with the increase of temperature, reaching the maximum at 160°C, the maximum being 63.2% (see Figure 2).

Example 3

Weigh 8.5g of commercial activated carbon, immerse it in distilled water and boil for 1h, then place it in a constant temperature drying oven at 103°C and dry it for 11h; then immerse it in a nitric acid solution with a mass fraction of 32%, and keep it 1.5h; filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 103°C for 11h.

Weigh 1.5g of phosphotungstic acid and dissolve it in 17mL of water. Add the treated activated carbon into the aqueous solution of phosphotungstic acid, stir manually until the mixture is uniform, seal and let it stand for 24 hours. The impregnated activated carbon was evaporated to dryness in a constant temperature water bath at 65°C, and then dried in a constant temperature drying oven at 105°C for 10 hours to obtain a catalyst precursor.

Put the above-mentioned precursor in a muffle furnace for roasting activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 6°C/min, when the temperature rises to 500 After ℃, stay for 3h. Cool naturally to room temperature to obtain a carbon-based phosphotungstic acid catalyst with a loading of 15%.

The results of desulfurization and denitrification experiments show that within the reaction temperature of 60-160°C, the desulfurization efficiency of the catalyst is very high and can be stabilized above 98%. When the reaction temperature is 80°C, the stabilization time of 100% desulfurization efficiency reaches 150 minutes; After 160°C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst first increased and then decreased with the increase of the reaction temperature, and the denitrification efficiency was the highest when the reaction temperature was 140°C, reaching 82.8% (as shown in Figure 2).

Example 4

Weigh 8.5g of commercial activated carbon, immerse it in distilled water and boil for 1h, then place it in a constant temperature drying oven at 105°C and dry it for 10h; then immerse it in a nitric acid solution with a mass fraction of 28%, and keep it 1h; filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 105°C for 10h.

Weigh 1.5g of phosphotungstic acid and dissolve it in 17mL of water. Add the treated activated carbon into the aqueous solution of phosphotungstic acid, stir manually until the mixture is uniform, seal and let it stand for 18 hours. The impregnated activated carbon was placed in a constant temperature water bath at 60°C and stirred continuously until it was evaporated to dryness, and then dried in a constant temperature drying oven at 100°C for 12 hours to obtain a catalyst precursor.

Put the above precursors in a muffle furnace for roasting activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 4°C/min, when the temperature rises to 400 After ℃, stay for 2h. Cool naturally to room temperature to obtain a carbon-based phosphotungstic acid catalyst with a loading of 15%.

The results of desulfurization and denitrification experiments show that the desulfurization efficiency of the catalyst is very high at a reaction temperature of 60-140°C and can be stabilized above 98%. When the reaction temperature is 80°C, the stabilization time of 100% desulfurization efficiency reaches 120 minutes; After 140°C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst first increased and then decreased with the increase of the reaction temperature, and the denitrification efficiency was the best when the reaction temperature was 140℃, reaching 68%.

Example 5

Weigh 8g of commercial activated carbon, immerse it in distilled water and boil for 2h, then place it in a constant temperature drying oven at 100°C for 12h; h; filter out the acid solution, and perform suction filtration and washing with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 100°C for 12 hours.

Weigh 2g of silicotungstic acid and dissolve it in 16mL of water. Add the treated activated carbon into the aqueous solution of silicotungstic acid, stir manually until the mixture is uniform, seal and let stand for 21 hours. The impregnated activated carbon was placed in a constant temperature water bath at 63°C and stirred continuously until evaporated to dryness, and then dried in a constant temperature drying oven at 102°C for 11 hours to obtain a catalyst precursor.

Put the above precursor in a muffle furnace for roasting activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 5°C/min, when the temperature rises to 600 After ℃, stay for 2.5h. Cool naturally to room temperature to obtain a carbon-based silicotungstic acid catalyst with a loading capacity of 20%.

The results of desulfurization and denitrification experiments show that within the reaction temperature of 80-160°C, the desulfurization efficiency of the catalyst is very high and can be stabilized above 98%. shown); when the reaction temperature exceeds 160 °C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst increased firstly and then decreased with the increase of reaction temperature, and the denitrification efficiency was the best when the reaction temperature was 160℃, reaching 51%.

Example 6

Weigh 8g of commercial activated carbon, immerse it in distilled water and boil for 1.5h, then place it in a constant temperature drying oven at 103°C for 12h; then immerse it in a nitric acid solution with a mass fraction of 32%, and keep it 2h; filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 103°C for 12h.

Weigh 2g of phosphomolybdic acid and dissolve it in 16mL of water. Add the treated activated carbon into the aqueous solution of phosphomolybdic acid, stir manually until the mixture is uniform, seal and let stand for 24 hours. The impregnated activated carbon was placed in a constant temperature water bath at 65°C and stirred continuously until it evaporated to dryness, and then dried in a constant temperature drying oven at 105°C for 12 hours to obtain a catalyst precursor.

Put the above precursor in a muffle furnace for roasting activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 6°C/min, when the temperature rises to 700 After ℃, stay for 3h. Cool naturally to room temperature to obtain a carbon-based phosphomolybdic acid catalyst with a loading of 20%.

The results of desulfurization and denitrification experiments show that the desulfurization efficiency of the catalyst is very high at a reaction temperature of 80-160°C and can be stabilized above 98%. shown); when the reaction temperature exceeds 160 °C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst first increased and then decreased with the increase of the reaction temperature, and the denitrification efficiency was the best when the reaction temperature was 160°C, reaching 45%.

Example 7

Weigh 8.5g of commercial activated carbon, immerse it in distilled water and boil for 1h, then place it in a constant temperature drying oven at 100°C for 12h; then immerse it in a nitric acid solution with a mass fraction of 30%, and keep it 2h; filter out the acid solution, filter and wash with deionized water until the pH is between 6-7; finally place it in a constant temperature drying oven at 105°C for 10h.

Weigh 1.5g of phosphotungstic acid and dissolve it in 17mL of water. Add the treated activated carbon into the aqueous solution of phosphotungstic acid, stir manually until the mixture is uniform, seal and let it stand for 20 hours. The impregnated activated carbon was placed in a constant temperature water bath at 60°C and stirred continuously until it evaporated to dryness, and then dried in a constant temperature drying oven at 105°C for 12 hours to obtain a catalyst precursor.

Put the above precursor in a muffle furnace for roasting and activation, use _N2 as the protective gas, and the gas flow rate is 200ml/min to ensure heat treatment under anaerobic conditions, the heating rate is 5°C/min, when the temperature rises to 800 After ℃, stay for 2h. Cool naturally to room temperature to obtain a carbon-based silicotungstic acid catalyst with a loading capacity of 15%.

The results of desulfurization and denitrification experiments show that the desulfurization efficiency of the catalyst is very high at a reaction temperature of 80-140°C and can be stabilized above 98%. shown); when the reaction temperature exceeds 140 °C, the desulfurization efficiency begins to decline. The denitrification efficiency of the catalyst first increased and then decreased with the increase of the reaction temperature, and the denitrification efficiency was the best when the reaction temperature was 160℃, reaching 41%.

Fig. 1 has provided and used the catalyst that the embodiment 5 of the present invention, embodiment 6 and embodiment 7 obtains to carry out in the desulfurization simulation test, the graph of desulfurization efficiency with desulfurization reaction time, as can be seen from the figure, the catalyst provided by the present invention In terms of desulfurization, it can maintain 100% desulfurization efficiency for a long time under the condition of low-temperature flue gas, which shows that the catalyst has a stable catalytic effect.

Fig. 2 has provided and used the catalyst that the embodiment 1 of the present invention obtains, embodiment 2 and embodiment 3 to carry out denitrification simulation test, the curve graph of denitrification efficiency with denitrification reaction temperature, as can be seen from the figure, the catalyst provided by the present invention It still has high denitrification efficiency in low temperature flue gas.

It can be seen from the above Examples 1-Example 7 that the catalyst provided by the present invention can simultaneously realize desulfurization and denitrification under low temperature reaction conditions; especially when the catalyst activation temperature is 300-500°C, the carbon-based heteropoly The acid catalyst also has high desulfurization and denitrification activity. The carbon-based phosphotungstic acid catalyst given in Example 3 has a desulfurization efficiency of 100% and a denitration efficiency of 82.8%.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (6)

1. the charcoal base heteropolyacid catalyst for low-temperature flue gas simultaneous SO_2 and NO removal, it is characterised in that with activated carbon for carrying Body, Keggin-type heteropoly acid is active component, and in this catalyst, the parts by weight content of each component is: the work of 80～85 weight portions Property charcoal, 15～20 Keggin-type heteropoly acids of weight portion.

Charcoal base heteropolyacid catalyst for low-temperature flue gas simultaneous SO_2 and NO removal the most according to claim 1, its feature exists It is the one in phosphomolybdic acid, phosphotungstic acid and silico-tungstic acid in being carried on the described Keggin-type heteropoly acid of activated carbon.

3. described in claim 1 or 2, it is used for the preparation method of the charcoal base heteropolyacid catalyst of low-temperature flue gas simultaneous SO_2 and NO removal, its It is characterised by mainly including following step of preparation process:

(1) under the conditions of 60～65 DEG C, by the salpeter solution pickling processes that activated carbon granule weight fraction is 28%～32%, It is washed to neutrality again, dries, be designated as NAC；

(2) weigh the heteropoly acid of 15～20 weight portions, soluble in water to make the heteropoly acid that weight fraction is 8.9%～12.0% molten Liquid；Weigh the NAC of 80～85 weight portions again, impregnated in the heteropoly acid solution that above-mentioned weight fraction is 8.9%～12%, stand No less than 18 hours, it is evaporated at 60～65 DEG C；Then it is dried 10～12h in 100～105 DEG C, prepares catalyst precursor；

(3) with N₂For protection gas, catalyst precursor being placed in Muffle kiln roasting, heating rate is not higher than 6 DEG C/min, roasting Burn temperature be 200～800 DEG C, roasting time be 2～3h, then naturally cool to room temperature and i.e. obtain finished catalyst.

It is used for the preparation method of the charcoal base heteropolyacid catalyst of low-temperature flue gas simultaneous SO_2 and NO removal the most according to claim 3, It is characterized in that activated carbon granule size is between 10～20 mesh.

It is used for the preparation method of the charcoal base heteropolyacid catalyst of low-temperature flue gas simultaneous SO_2 and NO removal the most according to claim 3, It is characterized in that described heteropoly acid liquor capacity is identical with the volume of added activated carbon.

6. the charcoal base heteropolyacid catalyst for low-temperature flue gas simultaneous SO_2 and NO removal described in claim 1 or 2 is applied, its feature It is, the flue gases of 80～160 DEG C are carried out desulphurization denitration simultaneously.