阅读说明：本技术 一种用于单质汞氧化的脱硝催化剂及其制备方法 (Denitration catalyst for elemental mercury oxidation and preparation method thereof ) 是由 李云涛 张茜梅 向莉 陈珙 亢选雄 于 2019-10-17 设计创作，主要内容包括：本发明公开了一种用于单质汞氧化的脱硝催化剂及其制备方法,采用选择性催化还原协同氧化技术,以氧化钒为活性组分、氧化钛为载体,且该氧化物催化剂中掺杂有溴,其中活性组分氧化钒采用浸渍法负载在载体上,载体氧化钛通过溶胶-凝胶法制备,溴掺杂的时间可以是制备载体氧化钛时,或者是负载活性组分氧化钒时,又或者是制备载体氧化钛和负载活性组分氧化钒时。本发明显著提高了对单质汞氧化的催化能力,320℃即可达到76％的单质汞氧化率,而脱硝效率基本不受影响,具备较强工业应用价值,可广泛应用于烟气中单质汞的氧化及后续固定。同时,本发明提供的催化剂上主要成分与传统的商业脱硝催化剂一致,因此,对催化剂应该具有的脱硝性能基本无影响。(The invention discloses a denitration catalyst for elemental mercury oxidation and a preparation method thereof, wherein a selective catalytic reduction synergistic oxidation technology is adopted, vanadium oxide is used as an active component, titanium oxide is used as a carrier, bromine is doped in the oxide catalyst, the active component vanadium oxide is loaded on the carrier by adopting an impregnation method, the carrier titanium oxide is prepared by a sol-gel method, and the bromine doping time can be used for preparing the carrier titanium oxide, or loading the active component vanadium oxide, or preparing the carrier titanium oxide and loading the active component vanadium oxide. The invention obviously improves the catalytic capability for the oxidation of the elemental mercury, can reach the oxidation rate of the elemental mercury of 76% at 320 ℃, has strong industrial application value and can be widely applied to the oxidation and subsequent fixation of the elemental mercury in the flue gas, and the denitration efficiency is basically not influenced. Meanwhile, the main components of the catalyst provided by the invention are consistent with those of the traditional commercial denitration catalyst, so that the denitration performance of the catalyst is basically not influenced.)

1. A denitration catalyst for elemental mercury oxidation is characterized by being prepared from the following raw materials in percentage by mass: 0.05 to 5.50 percent of bromine, 0.20 to 1.20 percent of vanadium, 59.00 to 60.00 percent of titanium and the balance of oxygen.

2. The catalyst according to claim 1, characterized in that the catalyst is prepared from the following raw materials in percentage by mass: 0.30 to 3.50 percent of bromine, 0.20 to 1.20 percent of vanadium, 59.67 percent of titanium and the balance of oxygen.

3. A method for preparing a denitration catalyst for elemental mercury oxidation according to claim 1 or 2, comprising the steps of:

(1) preparing a titanium oxide carrier by adopting a sol-gel method: weighing titanium precursor butyl titanate and acetylacetone, mixing and stirring to ensure that the molar ratio of [ acaCH ]/[ Ti ] is 2:1, then adding anhydrous ethanol with the volume of 3 times of the acetylacetone, stirring for 1 hour to obtain titanium sol, carrying out water bath concentration treatment, drying at 80-120 ℃, finally calcining for 1-4 hours in air, and screening for later use;

(2) loading active component vanadium oxide to a titanium oxide carrier by adopting an impregnation method: firstly, preparing an ammonium metavanadate solution by adopting a vanadium precursor ammonium metavanadate, weighing a certain amount of ammonium metavanadate, heating and dissolving the ammonium metavanadate solution in deionized water, and adjusting the pH value to 0.5-2.0 by using nitric acid; then weighing a certain amount of the screened titanium oxide carrier in proportion, adding an ammonium metavanadate solution in a certain stoichiometric ratio in proportion, soaking in a water bath, drying at 80-120 ℃, finally calcining in air for 1-4 hours, and completing loading to obtain a catalyst;

(3) bromine doping: and (3) dissolving a certain amount of ammonium bromide in one or two of ethanol or ammonium metavanadate solution, and obtaining the denitration catalyst for elemental mercury oxidation after the completion of the dissolving.

4. The preparation method according to claim 3, wherein the water bath concentration temperature in the step (1) is 70 ℃, and the drying time is 4-8 h; the calcination temperature is 400-600 ℃.

5. The method for preparing the nano-particles according to claim 3, wherein the temperature of the water bath in the step (2) is 70 ℃, and the dipping time is 2-5 h; the drying time is 4-8 h; the calcination temperature is 300-450 ℃.

6. The preparation method according to claim 3, wherein the bromine doping process of step (3) is performed at any one of the time of preparing the titanium oxide support, the time of loading the vanadium oxide as the active component, and the time of preparing the titanium oxide support and the vanadium oxide as the active component.

7. The preparation method according to claim 6, wherein the bromine doping process is selected to be performed when preparing the titanium oxide carrier, and an amount of ammonium bromide is dissolved in ethanol so that the mass percentage of bromine in the catalyst is 0.05-5.50.

8. The preparation method according to claim 6, wherein the bromine doping process is selected to be carried out when vanadium oxide as an active component is loaded, and ammonium bromide is dissolved in an ammonium metavanadate solution in an amount so that the mass percentage of bromine in the catalyst is 0.05-5.50.

9. The preparation method according to claim 6, wherein the bromine doping process is selected to be performed during the preparation of the titanium oxide carrier and the vanadium oxide carrying the active component, and ammonium bromide is dissolved in ethanol and ammonium metavanadate respectively in an amount such that the mass percentage of bromine in the catalyst is 0.05-5.50.

10. A denitration catalyst for elemental mercury oxidation prepared according to any one of the preparation methods of claims 3 to 9.

Technical Field

The invention belongs to the technical field of air pollution purification, relates to a catalyst, and particularly relates to a denitration catalyst for elemental mercury oxidation and a preparation method thereof.

Background

Mercury and its compounds have considerable harm to human digestive system, central nervous system and kidney, and are one of the persistent environmental pollutants which are continuously concerned at present. One of the major sources of mercury in the atmosphere is coal emissions. 2013, 19 months 1, the United nations environmental planning agency passed the Water Accident International convention aimed at controlling and reducing mercury emissions globally. Regulations require the control of mercury emissions from various large coal-fired utility and industrial boilers. Therefore, coal-fired mercury emission control is one of the environmental concerns.

The mercury control method of the coal-fired power plant can be divided into mercury removal before combustion (front-stage technology), mercury removal during combustion and mercury removal after combustion (back-stage technology), wherein the technologies which are widely applied comprise coal bromine spraying treatment (mercury removal before combustion) and brominated activated carbon injection technology (mercury removal after combustion), and the two technologies are applied industrially abroad, but the investment and the operation cost are high. On the other hand, coal-fired power plants like China are basically provided with Selective Catalytic Reduction (SCR) denitration, electrostatic dust removal and wet desulphurization facilities, and a large number of field test results at home and abroad show that the combined use of the SCR denitration, electrostatic dust removal and wet desulphurization facilities can effectively reduce the emission of gaseous mercury. The test results fully show that the cooperative mercury removal by using the installed SCR denitration, electrostatic dust removal and wet desulphurization facilities is an effective low-cost mercury removal technical route which is more in line with the situation of China.

The key point of realizing the cooperative mercury removal by utilizing SCR denitration, electrostatic dust removal and wet desulphurization facilities is to research and develop a denitration catalyst with high elemental mercury oxidation rate without influencing the denitration performance of the catalyst, otherwise, the denitration catalyst cannot be compensated. The main component of the conventional denitration catalyst is V₂O₅-WO₃(MoO₃)/TiO₂This is the optimum composition that has been validated for engineering applications over the last decades.In order to increase the oxidation rate of elemental mercury, the existing research and development idea is to add different transition metal oxides or their combinations, such as Co-Mn, CeO₂，Mo-Ru，CaCl₂，Au/TiO₂，CuCl₂/γ-Al₂O₃，RuO₂/rutile TiO₂，Fe₂O₃，CuCl₂The research results obtained by the ideas of-CoOx/Ti-CeOx, Co-MF, Mn-CuO, Cu-SSZ-13 and the like have important academic values, but have problems in application. For example, when the denitration performance of the catalyst is not considered, the extra injection of HCl is required during use, so that the operating cost and the risk of corrosion to a downstream flue and equipment are increased.

Therefore, a novel denitration catalyst with high elemental mercury oxidation rate and unaffected denitration performance needs to be developed, HCl and the like do not need to be sprayed additionally, smoke mercury emission is effectively controlled, and the economic and environmental protection pressure of industrial enterprises is reduced.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a denitration catalyst for elemental mercury oxidation and a preparation method thereof, and the novel denitration catalyst which has high elemental mercury oxidation rate and unaffected denitration performance under the condition of not additionally spraying HCl is developed through composition and preparation method improvement on the basis of the traditional commercial denitration catalyst, so that the mercury emission of flue gas is effectively controlled, and the economic and environmental protection pressure of industrial enterprises is reduced.

The invention is realized by the following technical scheme:

a denitration catalyst for elemental mercury oxidation is prepared from the following raw materials in percentage by mass: 0.05 to 5.50 percent of bromine, 0.20 to 1.20 percent of vanadium, 59.00 to 60.00 percent of titanium and the balance of oxygen.

Further, the catalyst is prepared from the following raw materials in percentage by mass: 0.30 to 3.50 percent of bromine, 0.20 to 1.20 percent of vanadium, 59.67 percent of titanium and the balance of oxygen.

A preparation method of a denitration catalyst for elemental mercury oxidation comprises the following steps:

(1) preparing a titanium oxide carrier by adopting a sol-gel method: weighing titanium precursor butyl titanate and acetylacetone, mixing and stirring to ensure that the molar ratio of [ acaCH ]/[ Ti ] is 2:1, then adding anhydrous ethanol with the volume of 3 times of the acetylacetone, stirring for 1 hour to obtain titanium sol, carrying out water bath concentration treatment, drying at 80-120 ℃, finally calcining for 1-4 hours in air, and screening for later use;

(2) loading active component vanadium oxide to a titanium oxide carrier by adopting an impregnation method: firstly, preparing an ammonium metavanadate solution by adopting a vanadium precursor ammonium metavanadate, weighing a certain amount of ammonium metavanadate, heating and dissolving the ammonium metavanadate solution in deionized water, and adjusting the pH value to 0.5-2.0 by using nitric acid; then weighing a certain amount of the screened titanium oxide carrier in proportion, adding an ammonium metavanadate solution in a certain stoichiometric ratio in proportion, soaking in a water bath, drying at 80-120 ℃, finally calcining in air for 1-4 hours, and completing loading to obtain a catalyst;

(3) bromine doping: and (3) dissolving a certain amount of ammonium bromide in one or two of ethanol or ammonium metavanadate solution, and obtaining the denitration catalyst for elemental mercury oxidation after the completion of the dissolving.

Further, the water bath concentration temperature in the step (1) is 70 ℃, and the drying time is 4-8 h; the calcination temperature is 400-600 ℃.

Further, the temperature of the water bath in the step (2) is 70 ℃, and the dipping time is 2-5 h; the drying time is 4-8 h; the calcination temperature is 300-450 ℃.

Further, the bromine doping process in the step (3) is performed at any time of preparing the titanium oxide carrier, loading the vanadium oxide as the active component, and preparing the titanium oxide carrier and loading the vanadium oxide as the active component.

Further, the bromine doping process is selected to be carried out when the titanium oxide carrier is prepared, and a certain amount of ammonium bromide is dissolved in ethanol, so that the mass percent of bromine in the catalyst is 0.05-5.50.

Further, the bromine doping process is carried out when vanadium oxide serving as an active component is loaded, and a certain amount of ammonium bromide is dissolved in an ammonium metavanadate solution, so that the mass percent of bromine in the catalyst is 0.05-5.50.

Further, the bromine doping process is selected to be carried out when titanium oxide as a carrier and vanadium oxide as a loaded active component are prepared, and a certain amount of ammonium bromide is respectively dissolved in ethanol and ammonium metavanadate, so that the mass percentage of bromine in the catalyst is 0.05-5.50.

The invention also discloses a denitration catalyst for elemental mercury oxidation, which is prepared by any one of the preparation methods.

The catalyst is doped with bromine, and the characteristics that the electronegativity of the bromine is smaller than that of oxygen and the ionic radii of the bromine and the oxygen are different greatly are utilized, so that the structure of the catalyst is influenced, the oxygen vacancy on the surface of the catalyst is increased, and the adsorption and oxidation of elemental mercury are promoted. Meanwhile, the main components of the catalyst provided by the invention are consistent with those of the traditional commercial denitration catalyst, so that the denitration performance of the catalyst is basically not influenced.

The invention has the beneficial effects that:

1. on the basis of keeping the prior denitration industrial application advantages of the vanadium/titanium catalyst, the catalyst provided by the invention obviously improves the oxidation activity of elemental mercury (the activity is improved by more than 3 times at the temperature of more than 300 ℃), so that the catalyst is more suitable for industrial application;

2. the catalyst provided by the invention does not need to additionally spray halides such as HCl and the like during application, so that the operation cost is reduced, and the corrosion risk to a subsequent flue and equipment is eliminated;

Detailed Description

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