阅读说明：本技术 一种适用于高含量有毒组分烟气的脱硝催化剂及其制备方法 (Denitration catalyst suitable for high-content toxic component flue gas and preparation method thereof ) 是由 杨治 于 2019-04-06 设计创作，主要内容包括：本发明公开了一种适用于高含量有毒组分烟气的脱硝催化剂及其制备方法,通过在脱硝催化剂中加入0.1～15%的硫酸氢铝,改性后的脱硝催化剂抗烟气中氟、砷、磷化合物中毒的能力得到很大的提高,改性催化剂可以通过浸渍法、喷涂法、挤出法制得。(The invention discloses a denitration catalyst suitable for high-content toxic component flue gas and a preparation method thereof, wherein 0.1-15% of aluminum bisulfate is added into the denitration catalyst, so that the capability of the modified denitration catalyst for resisting poisoning of fluorine, arsenic and phosphorus compounds in the flue gas is greatly improved, and the modified catalyst can be prepared by an impregnation method, a spraying method and an extrusion method.)

1. The denitration catalyst suitable for the high-content toxic component flue gas is characterized in that aluminum bisulfate is added into the denitration catalyst, the weight percentage of the aluminum bisulfate in the catalyst is 0.1-15%, the aluminum bisulfate is a component for resisting toxic components in the flue gas, and the toxic components in the flue gas are compounds of fluorine, arsenic and phosphorus.

2. A preparation method for realizing the denitration catalyst suitable for high-content toxic component flue gas in the claim 1 is characterized by comprising the following steps: the denitration catalyst suitable for high-content toxic component flue gas is prepared by one of (1) an impregnation method, (2) a spraying method and (3) an extrusion method.

3. The denitration catalyst suitable for high-toxic-component-content flue gas as claimed in claim 1, wherein: the fluorine compound is hydrogen fluoride, the arsenic compound is arsenic oxide, and the phosphorus compound is phosphoric acid or phosphate.

4. The denitration catalyst suitable for high-toxic-component-content flue gas as claimed in claim 1, wherein: the aluminum bisulfate is a component resisting toxic components in the smoke, the aluminum bisulfate source in the catalyst can also be aluminum persulfate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum acetate and aluminum oxide, and the aluminum compound which is not the aluminum bisulfate source can be converted into the aluminum bisulfate during the preparation or use.

5. The method for preparing the denitration catalyst suitable for the flue gas with high content of toxic components according to claim 2, wherein the denitration catalyst suitable for the flue gas with high content of toxic components is obtained by loading aluminum bisulfate or other aluminum salts described in claim 4 on the prepared denitration catalyst by an impregnation method, the weight percentage of the aluminum bisulfate in the catalyst is 0.1-15%, the other aluminum salts are calculated by the aluminum bisulfate, the impregnation method is a preferable modification method, and the method comprises the following steps:

(1) dissolving the calculated mass of aluminum salt in water, soaking the denitration catalyst for 2-5 minutes in an equal volume,

(2) the catalyst is drained at room temperature, the draining time is 30-50 minutes,

(3) and (3) drying the drained catalyst in an oven at the drying temperature of 100-150 ℃.

6. The method for preparing the denitration catalyst suitable for the flue gas with high content of toxic components according to claim 2, wherein the denitration catalyst suitable for the flue gas with high content of toxic components is obtained by loading aluminum bisulfate or other aluminum salts described in claim 4 on the prepared denitration catalyst by a spraying method, the weight percentage of the aluminum bisulfate in the catalyst is 0.1-15%, the other aluminum salts are calculated by the aluminum bisulfate, the spraying method is a modification method which is suboptimal, and the method comprises the following steps:

(1) dissolving aluminum salt with calculated mass in water, atomizing the aluminum salt solution by using spraying equipment, and uniformly spraying the aluminum salt solution on a commercial vanadium tungsten titanium denitration catalyst,

(2) the catalyst is drained at room temperature, the draining time is 30-50 minutes,

(3) drying the drained catalyst in an oven at 100-150 ℃,

(4) and (4) judging whether the steps (1) to (3) need to be repeated or not according to the loading amount of the aluminum salt.

7. The method according to claim 2, wherein the aluminum bisulfate or the other aluminum compounds described in claim 4 are introduced into the denitration catalyst during the production of the denitration catalyst by an extrusion method to produce the denitration catalyst suitable for the flue gas containing a high content of toxic components, the weight percentage of the aluminum bisulfate in the catalyst is 0.1-15%, and the other aluminum compounds are calculated as the aluminum bisulfate, and the method comprises the following steps:

(1) preparing mud materials: mixing anatase titanium dioxide, ammonium metavanadate, ammonium tungstate and aluminum bisulfate according to a formula amount by taking ammonium metavanadate as a source of vanadium pentoxide and ammonium tungstate as a source of tungsten trioxide, adding 0.6 time of water, 0.03 time of glass fiber yarns, 0.005 time of polyethylene oxide and 0.01 time of oxalic acid by weight of the mixture, mixing the mixture in a mixing mill for 1-8 hours to obtain pug,

(2) and (3) forming of the catalyst: and (2) preparing the pug into a honeycomb catalyst blank by an extruder, or a plate catalyst blank, or extruding and coating the pug on a steel wire mesh plate to prepare a plate catalyst blank containing a supporter, drying the prepared catalyst blank at 45-70 ℃ for 5-10 hours, then drying at 120-150 ℃ for 1-2 hours, calcining the dried catalyst at 270-300 ℃ for 3-4 hours, and finally calcining at 460-500 ℃ for 3-4 hours.

Technical Field

The invention relates to a denitration catalyst suitable for high-content toxic component flue gas and a preparation method thereof, and belongs to the technical field of nitrogen oxide control in environmental protection.

Background

Nitrogen oxides NOx are important atmospheric pollutants, and are one of the main pollutants causing disasters such as acid rain, photochemical fog, greenhouse effect and the like, and adverse effects of nitrogen oxides on the environment are seriously concerned by human beings. The combustion process using coal, biomass and garbage as fuel is the main source of nitrogen oxides, so the emission control of the flue gas generated by the combustion of the fuel is increasingly strengthened. Selective Catalytic Reduction (SCR) is widely used in the aforementioned flue gas treatment process because of its excellent reaction selectivity and activity. At present, the selective catalytic reduction technology mainly uses a vanadium tungsten titanium catalyst to reduce the emission of nitrogen oxides. The using temperature of the vanadium-tungsten-titanium catalyst is 300 to 400 ℃, so the catalyst is usually arranged in a high-temperature and high-dust flue gas environment and is easily poisoned by various toxic components in the flue gas. The toxic components in the flue gas include alkali metal compounds, alkaline earth metal compounds, phosphorus compounds, arsenic compounds, fluorine compounds. The catalyst poisoning reduces the activity and the service life of the catalyst, and increases the construction cost and the operation and maintenance cost of a user of the flue gas treatment equipment.

The fluorine element is one of harmful elements in coal, the fluorine content in the coal in China is 17-3088 mg per kilogram, the average content reaches 200 mg per kilogram, and is higher than the average content of 80 mg per kilogram in the world. Under the condition of water vapor, hydrogen fluoride in flue gas generated by burning coal can react with silicon dioxide in the denitration catalyst to generate volatile silicon tetrafluoride, the silicon tetrafluoride can be decomposed to generate silicon dioxide and hydrogen fluoride, and a grey-white compact hard shell is formed on the surface of the catalyst, so that the performance of the denitration catalyst is reduced. The hydrogen fluoride can also react with vanadium pentoxide in the catalyst to produce volatile vanadium fluoride acyl, causing vanadium loss from the catalyst and deactivation of the catalyst. The problem of the fluorosis of the vanadium-tungsten-titanium catalyst is solved by cleaning and supplementing active components (see Chinese patent application No. 201410814823.8).

Phosphorus widely exists in fossil fuel, sludge and food residues, and high-concentration phosphorus compounds in flue gas of coal-fired power plants and waste incineration plants can obviously inactivate widely used vanadium-tungsten-titanium catalysts, and the action mechanism is as follows: (1) the phosphorus compound can cause physical poisoning of the catalyst by blocking micropores of the catalyst, and (2) the phosphorus compound can also cause chemical poisoning of the catalyst by reducing the oxidation-reduction property of active centers by combining with vanadium pentoxide active centers. Lijunhua et al (Chinese application No. 201810365746.0) solved the problem of catalyst phosphorus poisoning by adding iron salts to vanadium tungsten titanium catalysts.

Arsenic has a great influence on the denitration catalyst, and most of arsenic in coal exists in the form of arsenic sulfide or iron arsenopyrite (fes 2. feas2) and the like, and a small part of arsenic exists in the form of an organic matter. The content of arsenic in coal in China also changes greatly, the content of arsenic varies from 0.5 to 80ppm, the content of gaseous arsenic oxide in high-temperature flue gas depends on the content of arsenic in coal and the combustion state of a boiler, and when the mass fraction of arsenic in coal exceeds 30ppm, the chemical life of the vanadium-tungsten-titanium SCR denitration catalyst is reduced by about 50% (see Chinese patent application No. 201510295692.1). Arsenic oxide in the flue gas can not only block micropores of the catalyst, but also be adsorbed on the carrier to react with active sites to form stable compounds without catalytic activity to poison active centers. The prior art generally improves the arsenic poisoning resistance of the catalyst by adding molybdenum oxide, but the addition of molybdenum oxide affects the activity, selectivity and temperature window of the catalyst. Li thinks (chinese patent application No. 201810371240.0) that by adding any one of magnesium salt, barium salt, cobalt salt or iron salt to the existing vanadium-tungsten-titanium and cerium-based catalyst system, the arsenic poisoning resistance of the catalyst is improved on the premise of ensuring the wide temperature activity window of the catalyst, but the catalytic activity of the vanadium-tungsten-titanium catalyst is slightly reduced after adding magnesium and barium.

It can be seen from the above description that, aiming at the poisoning effect of toxic components in flue gas on the existing commercial vanadium-tungsten-titanium catalyst, substances which interact with the toxic components are added, so that the interaction between the toxic components and the active center is avoided or delayed, and the inactivation of the catalyst is avoided or delayed.

In the practical application process of the denitration catalyst, the flue gas treated may contain tens to thousands ppm of sulfur dioxide in addition to the aforementioned phosphorus, fluorine and arsenic compounds. In order to reduce the corrosion of sulfuric acid generated by sulfur dioxide oxidation to downstream pipelines and equipment, the oxidation rate of sulfur dioxide of the catalyst by the national standard of vanadium denitration catalyst (see the national standard of the people's republic of China, honeycomb type flue gas denitration catalyst GB/T31587 and 2015 inner surface 7) is limited to be not more than 1%, and in order to achieve the standard, a catalyst manufacturer has strict internal limits on metal impurities of the catalyst, especially iron elements and alkali metal elements. However, most of the current patent applications or research reports do not disclose sulfur dioxide oxidation rate data of the relevant catalyst.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a denitration catalyst with fluorine, arsenic and phosphorus compound poisoning resistance and a manufacturing method thereof, wherein the catalytic activity of the denitration catalyst is not inferior to that of the existing commercial vanadium tungsten titanium catalyst, and the oxidation rate of sulfur dioxide is not more than 1%.

There are patents (chinese patent, application No. 200810196638.1, 201510704002.3) disclosing vanadium tungsten titanium denitration catalysts that can be used for high alkali flue gas, and the object of the invention is achieved by introducing aluminum sulfate into commercial vanadium tungsten titanium catalysts, which is the principle that aluminum sulfate captures alkali metal ions adsorbed on the catalyst, thereby avoiding or delaying the deactivation of the catalyst.

Based on the inspiration of the patent, aluminum bisulfate is introduced into the existing vanadium-tungsten-titanium catalyst, and more stable aluminum phosphate, aluminum arsenate and aluminum fluoride are generated under the actual use condition of the aluminum bisulfate, phosphorus-containing compounds, arsenic-containing compounds and fluorine-containing compounds, so that the action of the arsenic, fluorine and phosphorus compounds and the active component vanadium pentoxide in the catalyst is inhibited, and the deactivation of the catalyst is delayed or avoided. The applicant has not seen any report of the related inventive idea in the published reports.

Since aluminium bisulfate has acidic and non-oxidizing properties, it can: (1) promoting ammonia adsorption, thereby keeping and even increasing the activity of the catalyst, (2) inhibiting sulfur dioxide adsorption, maintaining low sulfur dioxide oxidation rate, and (3) stabilizing vanadium pentoxide active centers, thereby reducing the usage amount of tungsten oxide.

The invention adopts the following technical scheme: a commercial denitration catalyst is selected as a substrate, aluminum bisulfate is uniformly loaded in a pore channel in the substrate, and the denitration catalyst after modification treatment comprises the following components in percentage by weight: 60-95% of anatase titanium dioxide, 0.1-10% of vanadium pentoxide, 0.1-6% of tungsten trioxide, 0.01-19.95% of glass fiber component and 0.1-15% of aluminum bisulfate, wherein the glass fiber component of the catalyst is a mixture of silicon dioxide, aluminum oxide, calcium aluminate and calcium silicate. The aluminum bisulfate can be supported on the denitration catalyst by one of (1) an impregnation method, (2) a spraying method and (3) an extrusion method, and the impregnation method and the secondary spraying method are preferred.

The denitration catalyst suitable for the high-content toxic component flue gas is prepared by an impregnation method, and comprises the following steps: (1) dissolving aluminum salt with calculated mass in water, soaking the commercial vanadium tungsten titanium denitration catalyst for 2-5 minutes in an equal volume, (2) draining the catalyst at room temperature for 30-50 minutes, and (3) drying the drained catalyst in an oven at the drying temperature of 100-150 ℃.

The denitration catalyst suitable for high-content toxic component flue gas is prepared by a spraying method, and comprises the following steps: (1) dissolving aluminum salt with calculated mass in water, atomizing the aluminum salt solution by using a spraying device, and uniformly spraying the aluminum salt solution on the denitration catalyst, (2) draining the catalyst at room temperature for 30-50 minutes, (3) placing the drained catalyst in an oven for drying at the drying temperature of 100-150 ℃, and (4) judging whether steps (1) - (3) need to be repeated according to the loading amount of the aluminum salt. The spraying method is selected again because the equipment used in the spraying method is more complicated than that used in the dipping method and the uniformity of the spraying process is not easy to control.

The preparation method of the denitration catalyst suitable for the high-content toxic component flue gas by an extrusion method comprises the following steps: (1) preparing mud materials: mixing anatase titanium dioxide, ammonium metavanadate, ammonium tungstate and aluminum bisulfate according to a formula amount by taking ammonium metavanadate as a source of vanadium pentoxide and ammonium tungstate as a source of tungsten trioxide, adding 0.6 time of water, 0.03 time of glass fiber, 0.005 time of polyethylene oxide and 0.01 time of oxalic acid by weight of the mixture, and mixing the mixture in a mixing mill for 1-8 hours to obtain a pug, (2) forming a catalyst: and (2) preparing the pug into a honeycomb catalyst blank by an extruder, or a plate catalyst blank, or extruding and coating the pug on a steel wire mesh plate to prepare a plate catalyst blank containing a supporter, drying the prepared catalyst blank at 45-70 ℃ for 5-10 hours, then drying at 120-150 ℃ for 1-2 hours, calcining the dried catalyst at 270-300 ℃ for 3-4 hours, and finally calcining at 460-500 ℃ for 3-4 hours. The extrusion method is complicated in equipment compared with the dipping method and the spraying method, and aluminum bisulfate is partially decomposed during the calcination process, so that the method is not recommended when the weight percentage of aluminum bisulfate is less than 5%.

Since aluminum bisulfate is not readily available, aluminum sulfate and sulfuric acid can be dissolved in water in a molar ratio of 1:3 to obtain an aluminum bisulfate solution.

Aluminum bisulfate is introduced into the existing denitration catalyst, and the source of the aluminum bisulfate can also be aluminum persulfate, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum acetate and aluminum oxide. The aluminum compound derived from non-aluminum bisulfate can be converted to aluminum bisulfate during preparation or use by the following process:

(1) the aluminum persulfate reacts with water in the preparation process to generate oxygen and aluminum bisulfate;

(2) reacting sulfur dioxide adsorbed on the catalyst in the flue gas with oxygen and water to generate sulfuric acid;

(3) reacting aluminum sulfate with sulfuric acid generated in the step (2) to generate aluminum bisulfate;

(4) the aluminum nitrate is heated and decomposed to generate aluminum oxide, and the aluminum oxide reacts with the sulfuric acid generated in the step (2) to generate aluminum bisulfate;

(5) hydrolyzing aluminum chloride to generate aluminum hydroxide, decomposing the aluminum hydroxide to generate aluminum oxide, and reacting the aluminum oxide with the sulfuric acid generated in the step (2) to generate aluminum bisulfate;

(6) decomposing the aluminum acetate to generate aluminum oxide, and reacting the aluminum oxide with the sulfuric acid generated in the step (2) to generate aluminum bisulfate;

(7) and (3) reacting the alumina with the sulfuric acid generated in the step (2) to generate aluminum bisulfate.

The vanadium-tungsten-titanium denitration catalyst prepared by the invention has strong capability of resisting poisoning of arsenic, fluorine and phosphorus compounds. The poisoning-resistant component aluminum bisulfate does not volatilize or decompose in smoke below 400 ℃, does not affect the active component vanadium pentoxide of the catalyst, preferentially acts with arsenic, fluorine and phosphorus compounds adsorbed on the catalyst at high temperature to generate more stable aluminum arsenate, aluminum fluoride and aluminum phosphate, reduces the combination of the compounds containing arsenic, fluorine and phosphorus and vanadium active species of the catalyst to generate inactive vanadium species such as vanadyl phosphate, vanadyl fluoride, vanadium arsenate and the like and volatile unstable silicon fluoride, and delays the inactivation process of the catalyst. Meanwhile, the aluminum bisulfate can stabilize the vanadium pentoxide active center, thereby reducing the usage amount of tungsten oxide and greatly reducing the manufacturing cost of the catalyst.

The denitration catalyst is a vanadium tungsten titanium catalyst with high activity and low sulfur dioxide oxidation rate, can be used for denitration reaction of flue gas containing high-content arsenic, fluorine and phosphorus toxic components, and has the advantage of low manufacturing cost.

Detailed description of the preferred embodiments.

The present invention will be further described with reference to specific examples.

Unless otherwise specified, the test conditions for catalyst activity were: the reaction temperature is 360 ℃, and the space velocity is 20300h^-13% oxygen, 210ppm NO, NH in the reaction gas₃210ppm，SO₂600ppm，H₂O10 percent, nitrogen balance gas, a reaction activity coefficient K and a sulfur dioxide oxidation rate calculation method are referred to the national standard of the people's republic of China, honeycomb type flue gas denitration catalyst (GB/T31587-2015).

The calculation method of the concentration of the impregnation liquid used by the equal-volume impregnation method is referred to as 'an integral denitration catalyst suitable for the flue gas with high content of alkali metal elements and a preparation method thereof' (Chinese patent, application No. 201510704002.3).

The preparation method of the catalyst block for testing comprises the following steps: the purchased or self-made honeycomb catalyst is cut into a plurality of catalyst blocks with the axial length of 25 cm and the cross section of 3 multiplied by 3 holes. One piece of the catalyst was taken for testing the background activity of the catalyst. After taking two pieces of loaded aluminum salt, one piece of the loaded aluminum salt is used for testing the activity of the catalyst, and the other piece of the loaded aluminum salt is used for testing the activity of the catalyst after loading a toxic substance in the model. Although the mass percent of active material on the catalyst block was varied, the mass of vanadium pentoxide was equal and a comparison of the activity was made.