阅读说明：本技术 一种中低温光耦合选择性催化还原（scr）脱硝催化剂及其制备方法 (Medium-low temperature optical coupling Selective Catalytic Reduction (SCR) denitration catalyst and preparation method thereof ) 是由 汪澜 盛斌 卢蓓 盛树堂 李冰冰 孙花英 于 2020-12-07 设计创作，主要内容包括：本发明涉及水泥工业中大气污染物减排技术领域,尤其涉及一种中低温光耦合选择性催化还原(SCR)脱硝催化剂,包括载体和负载在载体上的活性成分；载体为非金属矿物；负载在载体上的活性成分为类钙钛矿结构的过渡-稀土双金属氧化物。本发明中的脱硝催化剂催化效率高,并且在低温条件下具有良好的活性及选择性。(The invention relates to the technical field of emission reduction of atmospheric pollutants in the cement industry, in particular to a medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst, which comprises a carrier and active ingredients loaded on the carrier; the carrier is a non-metallic mineral; the active component loaded on the carrier is transition-rare earth bimetallic oxide with a perovskite-like structure. The denitration catalyst has high catalytic efficiency and good activity and selectivity under the low-temperature condition.)

1. A medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst is characterized in that: comprises a carrier and an active ingredient loaded on the carrier;

the carrier is a non-metallic mineral; the active ingredient supported on the carrier has a perovskite-like structure [ (T)₁…T_n)_x(R₁…R_m)_1-xTiO₃]T represents a transition metal, R represents a rare earth metal, x>0, m and n are 1, 2 or 3;

wherein T is selected from one or more of vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh) and palladium (Pd); r is selected from one or more of lanthanum (La), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu); x is 0.2 to 0.5.

2. The medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst of claim 1, wherein: t is selected from one or more of niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh) and palladium (Pd); r is selected from one or more of promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), erbium (Er), thulium (Tm) and lutetium (Lu); x is 0.3 to 0.4.

3. The medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst of claim 1, wherein: the carrier is selected from attapulgite, sepiolite, bentonite or montmorillonite.

4. The medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst of claim 1, wherein: in the catalyst, the mass content of the active component accounts for 3-15 wt% of the mass of the carrier.

5. The medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst of claim 1, wherein: the precursor of the transition metal active component is selected from one or more of oxide, sulfate, nitrate, chloride and acetate, and specifically can be selected from one or more of rhodium oxide, rhodium nitrate, rhodium sulfate, palladium acetate, cobalt chloride, cobalt nitrate, palladium sulfate and niobium pentachloride;

the precursor of the rare earth element active component is selected from one or more of oxide, sulfate, nitrate, chloride, acetate and hydroxide, and specifically selected from one or more of promethium oxide, samarium sulfate, samarium nitrate and gadolinium hydroxide.

6. The preparation method of the medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst according to any one of claims 1 to 5, comprising the steps of:

1S: electrochemical reaction:

filling electrolyte prepared by a transition metal source (T) and a rare earth metal source (R), adding an additive, fixing an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process, connecting an electrode with a direct-current power supply, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after sparks are generated on the surface of the electrode;

2S: preparing a catalyst:

adding the carrier into the reaction solution in the step 1S, and mixing and stirring; and after the solution is completely adsorbed by the carrier, washing, drying and calcining to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

7. The method for preparing a medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst according to claim 6, wherein in the step 1S,

filling electrolyte prepared from a transition metal source (T) and a rare earth metal source (R) with a polytetrafluoroethylene beaker as a reaction tank, adding an additive, uniformly mixing, controlling the concentration of the additive to be 0.5-50 mg/ml, fixing an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process on a polytetrafluoroethylene fixing frame in parallel, adjusting the distance between the two electrodes to be 10-50 mm, adjusting the height of the electrodes to keep the immersion depth to be 10-50 mm, and then connecting the electrodes with a direct current power supply; and adjusting a voltage knob, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after plasma is generated on the surface of the electrode.

8. The method for preparing a medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst according to claim 6, wherein in the step 2S,

adding a carrier into the reaction liquid obtained in the step 1S, mixing, stirring and loading, soaking for 0.5-24h at the temperature of 20-60 ℃, centrifugally collecting precipitates after the solution is completely adsorbed by the carrier, washing with water, washing with alcohol, drying for 3-12h in a drying oven at the temperature of 50-120 ℃, calcining for 1-10h in a nitrogen atmosphere furnace at the temperature of 250-600 ℃, and finally calcining for 0.5-1h in a nitrogen atmosphere furnace at the temperature of 600-700 ℃ to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

9. The preparation method of the medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst according to claim 6, further comprising a preparation process of an electrolyte, step 1A, before the step 1S:

weighing a rare earth metal source (R) and a transition metal source (T), respectively dissolving the rare earth metal source (R) and the transition metal source (T) in deionized water which is boiled and used after being cooled to room temperature, uniformly mixing the rare earth metal source (R) and the transition metal source (T), raising the temperature, adding 0.10MHCl to adjust the acidity of the solution to be 3-11, and preparing electrolyte with the total concentration of metal cations to be 0.5M.

10. The method for preparing a medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst according to claim 6,

the additive comprises one or more of a surfactant and/or other additives;

the pretreatment process comprises the steps of mechanically polishing to remove an oxidation film, polishing with 1-micron aluminum oxide, soaking in acetone for ultrasonic cleaning for 2-10 minutes to remove surface grease, respectively washing the surface with boiled pretreated ionic water and ethanol, and finally drying in a drying oven at low temperature for later use;

the transition metal plate includes a metal plate of vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh), or palladium (Pd).

Technical Field

The invention relates to the technical field of emission reduction of atmospheric pollutants in cement industry, in particular to a medium-low temperature optical coupling Selective Catalytic Reduction (SCR) denitration catalyst and a preparation method thereof.

Background

Nitrogen oxides, which are one of the main pollutants of the atmosphere, pose great harm to human health and living environment, such as respiratory diseases, acid rain, photochemical smog, PM2.5 and the like, and therefore, the pollution control of nitrogen oxides becomes particularly urgent. The traditional denitration method mainly comprises a non-selective catalytic reduction method (SNCR) and a selective catalytic reduction method (SCR). SNCR tends to require higher costs and presents secondary pollution. SCR mainly utilizes a vanadium-titanium catalyst, takes ammonia gas, urea and the like as reducing agents to decompose nitrogen oxides into harmless nitrogen, but has the disadvantages of low-temperature activity, high energy consumption, relatively high requirement on working temperature (300-400 ℃) and easy generation of N in a high-temperature range₂O causes N₂The selectivity is reduced, and some byproducts are easily generated. Therefore, the development of medium-low temperature efficient catalyst and new method is of great significance.

The photocatalysis technology is a novel denitration technology which utilizes solar energy to catalyze and degrade pollutants and has application potential, and has the advantages of mild reaction conditions, low energy consumption, less secondary pollution and the like; the method can be divided into 3 types: light oxidation denitration, light decomposition denitration and light coupling selective catalytic reduction denitration. The photooxidation denitration is easy to form nitrate on the surface of the catalyst, and when the nitrate is accumulated to a certain concentration, the catalyst is easy to corrode, so that the activity of the catalyst is reduced, and the water is required to be cleaned and regenerated. The direct decomposition of nitrogen oxide by photoreduction is a feasible scheme, but the conversion rate of nitrogen oxide is low, and N is easily generated₂O、NO₂And the like. The photo-coupled selective catalytic reduction denitration has high nitrogen oxide conversion rate in a low-temperature reaction interval (even room temperature).By using TiO₂Or dye modified TiO₂A series of optical coupling denitration studies were conducted, but TiO₂The forbidden band width of the optical coupling SCR is wide (3.2eV), and the optical coupling SCR only responds to ultraviolet light with high energy and hardly responds to visible light which accounts for most of solar energy, so that the application prospect of the optical coupling SCR is limited.

The perovskite has the characteristics of structural and compositional diversity, oxidation state and defect variability, richness in physical and chemical properties and the like, and part of perovskite has a narrow band gap and good visible light response. Ideal ABO₃The perovskite structure is a cubic structure, and A site cations and B site cations in the structure have higher tolerance and can be substituted by other various metal cations, so that special physical and chemical properties are generated. But its use is limited due to its large particle size which makes it prone to agglomeration. In order to solve the above problems, mineral materials in the natural world are receiving much attention.

Chinese patent CN 105642299A, "a nickel-doped lanthanum ferrite/clay nano-structure composite material, its preparation method and application", is prepared by adding lanthanum nitrate, nickel nitrate, ferric nitrate, citric acid and clay into deionized water, stirring, transferring into a water bath kettle, evaporating to obtain wet gel, drying, calcining, oven drying, and grinding. The composite material is used as a catalyst for photocatalytic denitration, and compared with the traditional SCR denitration, NH is added₃The dosage of the catalyst is reduced, and the conversion efficiency of NO is improved to a certain extent at low temperature.

Therefore, the environment-friendly medium-low temperature type SCR reaction catalyst is further developed, the technical problem of photocatalytic denitration is solved, and the method is applied to NO in the cement industry of China and other industrial industries (including the power industry and the non-power industry)_xEmission reduction has important significance.

Disclosure of Invention

The invention provides a medium-low temperature optical coupling Selective Catalytic Reduction (SCR) denitration catalyst, which well solves the technical problems that the existing SCR denitration catalyst cannot cover low-temperature and medium-temperature regions simultaneously, the low-temperature activity is low, the energy consumption is high, and the requirement on the working temperature is high.

According to one aspect of the inventionThe medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst comprises a carrier and an active component loaded on the carrier; the carrier is a non-metallic mineral; the active ingredient supported on the carrier has a perovskite-like structure [ (T)₁…T_n)_x(R₁…R_m)_1-xTiO₃]T represents transition metal, R represents rare earth metal, x is 0.2-0.5, and m and n are 1, 2 or 3;

wherein T is selected from one or more of vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh) and palladium (Pd); r is selected from one or more of lanthanum (La), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

Both transition metals and rare earth oxides have been shown to have certain medium and low temperature SCR activity; can be used as a better catalyst promoter component, can increase the concentration of oxygen on the surface of the denitration catalyst in the reaction process and increase the catalytic activity of the denitration catalyst; but also has dispersing performance and improves the thermal stability of the denitration catalyst. At the same time, (T)₁…T_n)_x(R₁…R_m)_1-xTiO₃The rare earth composite metal oxide is a typical perovskite-like structure rare earth composite metal oxide, and has a narrow forbidden band width (2.1eV), so that the rare earth composite metal oxide has a good response to visible light. The addition of the rare earth metal (R) promotes the acceleration of the recombination rate of the photo-generated electron-hole pairs, a heterojunction structure is formed in a solid solution, the separation of the photo-generated electron-hole pairs is facilitated, and the denitration efficiency is improved. The added transition metal (T) enters the solid solution crystal lattice in a doping mode to form a capture trap of a photo-generated electron-hole pair, so that the separation of photo-generated carriers is effectively prolonged, the denitration activity is enhanced, and the response of photocatalysis is expanded.

Preferably, T is selected from one or more of niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh) and palladium (Pd); r is selected from one or more of promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), erbium (Er), thulium (Tm) and lutetium (Lu).

The transition metal (T) can increase the concentration of oxygen on the surface of the denitration catalyst in the reaction process and increase the catalytic activity of the denitration catalyst, but further research finds that the high content of the transition metal causes the unsatisfactory thermal stability of the catalyst in medium and low temperature environments. The addition of the rare earth metal (R) promotes the acceleration of the recombination rate of the photo-generated electron-hole pairs, a heterojunction structure is formed in a solid solution, the separation of the photo-generated electron-hole pairs is facilitated, and the denitration efficiency is further improved. In the invention, the content of the transition metal (T) and the rare earth metal (R) is selected to increase the synergistic catalytic action of the transition metal (T) and the rare earth metal (R), and the value of x is 0.2-0.5, so that the catalyst has higher denitration efficiency and higher activity and selectivity in a low-temperature region. In addition, the appropriate content of the transition metal (T) and the rare earth metal (R) is selected, so that the material has a narrower forbidden band width (2.1eV), photogenerated carriers are rapidly separated, the visible light response range is expanded, the utilization efficiency of solar energy is improved, and the denitration reaction efficiency of the photo-coupled SCR is improved. Preferably, x is 0.3 to 0.4.

In the invention, natural minerals which are low in price and easy to obtain are selected as a carrier, and the carrier has a microporous silicon-oxygen tetrahedron three-dimensional chain/layer/net structure, abundant surface groups, a larger specific surface area, more acidic active sites and dispersible water-containing magnesium-aluminum-rich natural silicate minerals; the catalyst has good in-situ physical adsorption capacity on gas molecules, so that the active components can be fully contacted with nitrogen oxides in the later catalysis process; meanwhile, the diffusion of Mg, Al, Ca and other ions in the attapulgite can enter perovskite lattices to increase the impurity energy level, increase the photoresponse range and reduce the recombination of photon-generated carriers. The carrier is selected from attapulgite, sepiolite, bentonite or montmorillonite.

Preferably, in the catalyst, the mass content of the active component accounts for 3 wt% -15 wt% of the mass of the carrier.

Preferably, the precursor of the transition metal active component is selected from one or more of oxide, sulfate, nitrate, chloride and acetate, and specifically can be selected from one or more of rhodium oxide, rhodium nitrate, rhodium sulfate, palladium acetate, cobalt chloride, cobalt nitrate, palladium sulfate and niobium pentachloride; the mass of the introduced transition metal accounts for 1-9 wt% of the mass of the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst, and the preferable effective component is acid salt accounting for 4-6 wt%; this is because a proper amount of transition metal increases the number of acid sites on the surface of the denitration catalyst, and suppresses the conversion of the anatase-like crystal form to the rutile phase.

The precursor of the rare earth element active component is selected from one or more of oxide, sulfate, nitrate, chloride, acetate and hydroxide, and specifically selected from one or more of promethium oxide, samarium sulfate, samarium nitrate and gadolinium hydroxide; the mass of the introduced rare earth elements accounts for 2-6 wt% of the mass of the medium-low temperature optical coupling Selective Catalytic Reduction (SCR) denitration catalyst, and preferably, the precursor of the rare earth element active component is a nitrate series and accounts for 3-5 wt%; the rare earth element has the property of an electron storage when the 4f orbit which is not filled with electrons is used as an active component of the denitration catalyst, so that free electrons generated along with the formation of oxygen vacancies are effectively stored, and the adsorption and activation of molecular oxygen are well promoted; the appropriate amount of rare earth elements can increase the oxygen vacancy of the surface structure defect of the catalyst, improve the surface acidity, increase the specific surface area and enhance the denitration activity.

According to a second aspect of the present invention, there is provided a method for preparing the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst, comprising the following steps:

1S: electrochemical reaction:

filling electrolyte prepared by a transition metal source (T) and a rare earth metal source (R), adding an additive, fixing an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process, connecting an electrode with a direct-current power supply, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after sparks are generated on the surface of the electrode;

2S: preparing a catalyst:

adding the carrier into the reaction solution in the step 1S, and mixing and stirring; and after the solution is completely adsorbed by the carrier, washing, drying and calcining to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

In the step 1S, a polytetrafluoroethylene beaker is used as a reaction tank, electrolyte prepared from a transition metal source (T) and a rare earth metal source (R) is filled, an additive is added and uniformly mixed, the concentration of the additive is controlled to be 0.5-50 mg/ml, an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 10-50 mm, the height of the electrodes is adjusted to keep the immersion depth to be 10-50 mm, and then the electrodes are connected with a direct current power supply; and adjusting a voltage knob, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after plasma is generated on the surface of the electrode.

And in the step 2S, adding a carrier into the reaction liquid obtained in the step 1S, mixing, stirring and loading, controlling the temperature to be 20-60 ℃, soaking for 0.5-24h, after the solution is completely adsorbed by the carrier, centrifugally collecting precipitates, washing with water, washing with alcohol, placing in a drying oven at 50-120 ℃, drying for 3-12h, calcining in a furnace with a nitrogen atmosphere of 600 ℃ and 250 ℃ for 1-10h, and finally calcining in a furnace with a nitrogen atmosphere of 700 ℃ and 600 ℃ for 0.5-1h to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

The preparation process of the electrolyte before the step 1S comprises the following steps of 1A: weighing a rare earth metal source (R) and a transition metal source (T), respectively dissolving the rare earth metal source (R) and the transition metal source (T) in deionized water which is boiled and cooled to room temperature, uniformly mixing the rare earth metal source (R) and the transition metal source (T), raising the temperature, adding 0.10M HCl to adjust the acidity of the solution to be 3-11, and preparing electrolyte with the total concentration of metal cations to be 0.5M.

The additive comprises one or more of a surfactant and/or other additives.

Preferably, the additives include one or more of surfactants (CTAB, PEG1000) or/and other additives (PVP, ethanol).

The pretreatment process comprises the steps of mechanically polishing to remove an oxidation film, polishing with 1-micron aluminum oxide, soaking in acetone for ultrasonic cleaning for 2-10 minutes to remove surface grease, respectively washing the surface with boiled pretreated ionic water and ethanol, and finally drying in a drying oven at low temperature for later use; the transition metal plate includes a metal plate of vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh), or palladium (Pd). In the present application, the molar ratio of the transition metal source to the transition metal anode plate element is 0.2 to 5.

Compared with the traditional SCR denitration, the invention introduces the perovskite-like mineral structure to realize the light source catalysis with wider range, and realizes the medium and low temperature denitration. The application expands the response range to visible light, and NH is irradiated by a light source₃The migration of electrons occurs to generate NH₂ ^-Radical, with NH₂Increase of-groups, NH₂NH resulting from attack of the group by NO₂The NO intermediate products are increased and decomposed into N₂And H₂O, NH can be more fully utilized than in conventional SCR₃，NH₃The dosage of the catalyst is reduced, and the conversion efficiency of NO is obviously improved at low temperature.

Compared with the prior art, the invention has the following advantages:

(1) the catalyst prepared by adopting an electrochemical-impregnation composite method is coupled perovskite [ (T)₁…T_n)_x(R₁…R_m)_1-xTiO₃]The composite catalyst consists of a structure and a nonmetal clay mineral porous structure carrier, the particle size of the perovskite-like active component is less than 10nm, the load is uniform, the dispersion is uniform, the cost is reduced, the synergistic effect of the perovskite-like structure and the porous structure is exerted, and the abundant micro-surface of the carrier is utilized to be beneficial to the load and dispersion optimization of the active component;

(2) the active component with the perovskite-like structure prepared by the electrochemical method in the invention is perovskite-like [ (T)₁…T_n)_x(R₁…R_m)_1-xTiO₃]In the structure forming process, the doping effect of the transition metal and the system effect of the rare earth metal are added, so that the structure has a narrower forbidden bandwidth (2.1eV), and photo-generated carriers are quickly separated, so that the visible light response range is expanded, the utilization efficiency of solar energy is improved, and the light coupling SCR denitration reaction efficiency is improved;

(3) the perovskite type active component is generally prepared by a precipitation method and the like, is granular and is easy to agglomerate. The catalyst is prepared by an electrochemical method, and active components can be fully contacted with nitric oxide in the later catalytic process by utilizing the nonmetal ore load with abundant surface groups;

(4) the non-metallic ore carrier is low in price and easy to obtain, the surfaces of the non-metallic ore and the surfaces of the active components prepared by electrochemistry are different in positive and negative through methods such as acidity regulation and the like, and the composite effect of the non-metallic ore and the active components is obviously improved due to the attraction of positive and negative charges; the diffusion of Mg, Al, Ca and other ions in the nonmetallic ore can enter perovskite-like crystal lattices to increase the impurity energy level, increase the photoresponse range and reduce the recombination of photon-generated carriers, and is different from the doping of materials without photoresponse in the prior art; meanwhile, the microporous structure of the molecular sieve in the clay is beneficial to the transmission of gas molecules, and the active sites of catalytic reaction are enlarged;

(5) compared with the traditional SCR denitration, the invention introduces the perovskite-like mineral structure to realize the light source catalysis with wider range, and realizes the medium and low temperature denitration. More fully utilize NH₃，NH₃The dosage of the catalyst is reduced, and the conversion efficiency of NO is obviously improved at low temperature.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

The preparation method of the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst comprises the following steps:

1S: electrochemical reaction:

filling electrolyte prepared by a transition metal source (T) and a rare earth metal source (R), adding an additive, fixing an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process, connecting an electrode with a direct-current power supply, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after sparks are generated on the surface of the electrode;

2S: preparing a catalyst:

adding the carrier into the reaction solution in the step 1S, and mixing and stirring; and after the solution is completely adsorbed by the carrier, washing, drying and calcining to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst. Step 1S, a polytetrafluoroethylene beaker is used as a reaction tank, electrolyte prepared from a transition metal source (T) and a rare earth metal source (R) is filled, an additive is added and uniformly mixed, the concentration of the additive is controlled to be 0.5-50 mg/ml, an anode transition metal plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 10-50 mm, the height of the electrodes is adjusted to keep the immersion depth to be 10-50 mm, and then the electrodes are connected with a direct current power supply; and adjusting a voltage knob, raising the voltage to a breakdown voltage, and continuously reacting for 2-30min after plasma is generated on the surface of the electrode.

And in the step 2S, adding a carrier into the reaction liquid obtained in the step 1S, mixing, stirring and loading, controlling the temperature to be 20-60 ℃, soaking for 0.5-24h, after the solution is completely adsorbed by the carrier, centrifugally collecting precipitates, washing with water, washing with alcohol, placing in a drying oven at 50-120 ℃, drying for 3-12h, calcining in a furnace with a nitrogen atmosphere of 600 ℃ and 250 ℃ for 1-10h, and finally calcining in a furnace with a nitrogen atmosphere of 700 ℃ and 600 ℃ for 0.5-1h to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

The preparation process of the electrolyte before the step 1S comprises the following steps of 1A: weighing a rare earth metal source (R) and a transition metal source (T), respectively dissolving the rare earth metal source (R) and the transition metal source (T) in deionized water which is boiled and cooled to room temperature, uniformly mixing the rare earth metal source (R) and the transition metal source (T), raising the temperature, adding 0.10M HCl to adjust the acidity of the solution to be 3-11, and preparing electrolyte with the total concentration of metal cations to be 0.5M.

The additive comprises one or more of a surfactant and/or other additives; the pretreatment process comprises the steps of mechanically polishing to remove an oxidation film, polishing with 1-micron aluminum oxide, soaking in acetone for ultrasonic cleaning for 2-10 minutes to remove surface grease, respectively washing the surface with boiled pretreated ionic water and ethanol, and finally drying in a drying oven at low temperature for later use; the transition metal plate includes a metal plate of vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), niobium (Nb), technetium (Tc), ruthenium (Ru), rhodium (Rh), or palladium (Pd).

Some specific examples of medium and low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalysts of the present application are listed below. The present invention is specifically described below with reference to examples, but the present invention is not limited to the examples.

Examples

Example 1

1S: electrochemical reaction:

a150 mL polytetrafluoroethylene beaker is used as a reaction tank, 0.5M lanthanum chloride electrolyte is filled, CTAB is added and uniformly mixed, the concentration of CTAB is controlled to be 0.5mg/mL, an anode niobium plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 20mm, the height of the electrodes is adjusted to keep the immersion depth at 20mm, and then the electrodes are connected with a direct-current power supply (the current regulation range is 3A, and the voltage regulation range is 150V). And manually adjusting a voltage knob, increasing the voltage to breakdown voltage, and continuously reacting for 10min after plasma is generated on the surface of the electrode.

2S, catalyst preparation:

adding a sepiolite carrier, controlling the mass of the carrier to be 500 times of that of the photocatalytic component, mixing, stirring and loading, controlling the temperature to be 60 ℃, soaking for 12 hours, centrifugally collecting precipitates after the solution is completely adsorbed by the carrier, washing with water, washing with alcohol, drying in a drying oven at 100 ℃ for 3 hours, calcining in a 500 ℃ nitrogen atmosphere furnace for 2 hours, and finally calcining in a 650 ℃ nitrogen atmosphere furnace for 0.5 hour to obtain the medium-low temperature photo-coupling Selective Catalytic Reduction (SCR) denitration catalyst.

Example 2

1S: electrochemical reaction:

a300 mL polytetrafluoroethylene beaker is used as a reaction tank, 0.5M lanthanum nitrate and cobalt chloride electrolyte are filled, PEG1000 is added, the mixture is uniform, the concentration of the PEG1000 is controlled to be 10mg/mL, an anode nickel plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 50mm, the height of the electrodes is adjusted to keep the immersion depth at 50mm, and then the electrodes are connected with a direct-current power supply (the current adjustment range is 3A, and the voltage adjustment range is 150V). And manually adjusting a voltage knob, increasing the voltage to breakdown voltage, and continuously reacting for 15min after plasma is generated on the surface of the electrode.

2S, catalyst preparation:

adding a bentonite carrier, controlling the mass of the carrier to be 300 times of that of the photocatalytic component, mixing, stirring and loading, controlling the temperature to be 20 ℃, soaking for 24 hours, centrifugally collecting precipitates after the solution is completely adsorbed by the carrier, washing with water, washing with alcohol, placing in a drying oven for drying at 120 ℃ for 5 hours, calcining in a 600 ℃ nitrogen atmosphere furnace for 4 hours, and finally calcining in a 700 ℃ nitrogen atmosphere furnace for 1 hour to obtain the medium-low temperature photo-coupling Selective Catalytic Reduction (SCR) denitration catalyst.

Example 3

1S: electrochemical reaction

A200 mL polytetrafluoroethylene beaker is used as a reaction tank, 0.5M lanthanum acetate and technetium chloride electrolyte are filled, ethanol is added, the mixture is uniformly mixed, the concentration of the ethanol is controlled to be 50mg/mL, an anode vanadium plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 30mm, the height of the electrodes is adjusted to keep the immersion depth at 30mm, and then the electrodes are connected with a direct-current power supply (the current adjustment range is 3A, and the voltage adjustment range is 150V). And manually adjusting a voltage knob, increasing the voltage to breakdown voltage, and continuously reacting for 10min after plasma is generated on the surface of the electrode.

2S, catalyst preparation:

adding a perlite carrier, controlling the mass of the carrier to be 10 times of that of the photocatalytic component, mixing, stirring and loading, controlling the temperature to be 30 ℃, soaking for 18h, after the solution is completely adsorbed by the carrier, centrifugally collecting the precipitate, washing with water, washing with alcohol, placing in a drying oven at 50 ℃, drying for 12h, calcining in a nitrogen atmosphere furnace at 250 ℃ for 10h, and finally calcining in a nitrogen atmosphere furnace at 630 ℃ for 0.75h to obtain the medium-low temperature photo-coupling Selective Catalytic Reduction (SCR) denitration catalyst.

Example 4

1S: electrochemical reaction

A400 mL polytetrafluoroethylene beaker is used as a reaction tank, 0.5M of niobium nitrate and lutetium chloride electrolyte are filled, PVP is added and uniformly mixed, the concentration of the PVP is controlled to be 30mg/mL, an anode manganese plate and a cathode Ti plate which are subjected to a pretreatment process are parallelly fixed on a polytetrafluoroethylene fixing frame, the distance between the two electrodes is 20mm, the height of the electrodes is adjusted to keep the immersion depth at 40mm, and then the electrodes are connected with a direct-current power supply (the current adjustment range is 3A, and the voltage adjustment range is 150V). And manually adjusting a voltage knob, increasing the voltage to breakdown voltage, and continuously reacting for 20min after plasma is generated on the surface of the electrode.

2S, catalyst preparation:

adding an attapulgite carrier, controlling the mass of the carrier to be 150 times of that of the photocatalytic component, mixing, stirring and loading, controlling the temperature to be 40 ℃, soaking for 6h, centrifugally collecting precipitates after the solution is completely adsorbed by the carrier, washing with water, washing with alcohol, placing in a drying oven at 90 ℃, drying for 8h, calcining in a 400 ℃ nitrogen atmosphere furnace for 8h, and finally calcining in a 670 ℃ nitrogen atmosphere furnace for 1h to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

Example 5

1S: electrochemical reaction

A200 mL polytetrafluoroethylene beaker is used as a reaction tank, 0.5M samarium nitrate electrolyte is filled, PEG1000 is added, the mixture is uniform, the concentration of the PEG1000 is controlled to be 20mg/mL, an anode iron plate and a cathode Ti plate which are subjected to a pretreatment process are fixed on a polytetrafluoroethylene fixing frame in parallel, the distance between the two electrodes is 40mm, the height of the electrodes is adjusted to keep the immersion depth at 35mm, and then the electrodes are connected with a direct-current power supply (the current adjustment range is 3A, and the voltage adjustment range is 150V). And manually adjusting a voltage knob, increasing the voltage to breakdown voltage, and continuously reacting for 30min after plasma is generated on the surface of the electrode.

2S, catalyst preparation:

adding a montmorillonite carrier, controlling the mass of the carrier to be 60 times of that of the photocatalytic component, mixing, stirring and loading, controlling the temperature to be 50 ℃ for soaking for 3h, after the solution is completely adsorbed by the carrier, centrifugally collecting the precipitate, washing with water and alcohol, placing in a drying oven for drying at 80 ℃ for 6h, then calcining in a 300 ℃ nitrogen atmosphere furnace for 6h, and finally calcining in a 680 ℃ nitrogen atmosphere furnace for 0.75h to obtain the medium-low temperature photo-coupled Selective Catalytic Reduction (SCR) denitration catalyst.

Test example

In order to further embody the beneficial effects of the present invention, the denitration effects of the above examples and comparative examples were respectively tested. The specific test method comprises the following steps: each catalyst was placed in a tubular fixed bed reactor with a reaction gas composition (by volume) of 700ppm NOx, 700ppm NH₃，100ppm SO₂，5％O₂，10％H₂O，N₂As carrier gas, the space velocity (GHSV) is 30000h^-1. Heating the reactor from room temperature to 360 deg.C at a speed of 10 deg.C/min, maintaining at 20 deg.C, stabilizing for 30min, and detecting NO and NO respectively in an online manner by a nitrogen oxide analyzer (Thermo42iHL) after the simulated gas passes through the catalyst₂The concentration of (c).

The material obtained by the method has good SCR catalytic activity in the range of 150-360 ℃: the catalyst has NOx conversion rate not less than 80% under the low temperature condition (150 ℃ plus 200 ℃), NOx conversion rate not less than 92% under the temperature of 200 ℃ plus 360 ℃, and has good SO resistance₂And H₂And (4) O performance. Compared with the traditional V₂O₅/TiO₂The denitration efficiency of the catalyst in a low-temperature area is greatly improved.

The above examples are only for illustrating the technical solutions of the present invention, and are not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.