Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to overcome the defect that the existing SCR low-temperature catalyst resists SO2The copper-doped phosphomolybdic acid low-temperature denitration catalyst can resist SO on the basis of ensuring the low-temperature denitration efficiency2And increased capacity for water vapor.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention discloses a copper-doped phosphomolybdic acid low-temperature denitration catalyst, which is characterized by comprising the following components in percentage by weight: the catalyst adopts anatase type TiO2As a carrier, phosphomolybdic acid, copper nitrate, polyethylene glycol and hexadecyl trimethyl ammonium bromide constitute active components.
Furthermore, the molar ratio of Cu to Mo in the active component is (0-4) to 1, the mass of cetyl trimethyl ammonium bromide in the active component accounts for 10-60% of the mass of phosphomolybdic acid, and the mass of the active component in the catalyst accounts for 5-15% of the total mass of the catalyst.
Further, the anatase type TiO2The specific surface area of (1) is 300-350m2/g。
Furthermore, the preparation process of the active component comprises the following steps: phosphomolybdic acid, copper nitrate, hexadecyl trimethyl ammonium bromide and polyethylene glycol are dissolved in distilled water and uniformly mixed, and then the active component is obtained after drying, drying and calcining treatment.
The invention discloses a preparation method of a copper-doped phosphomolybdic acid low-temperature denitration catalyst, which is characterized by comprising the following steps of:
the method comprises the following steps: preparation of the active ingredient
(1) Mixing phosphomolybdic acid, copper nitrate, hexadecyl trimethyl ammonium bromide and polyethylene glycol, dissolving, and stirring at a constant speed for 1-1.5 h;
(2) drying the mixture obtained in the step (1) at a constant speed, and evaporating water to dryness;
(3) drying the mixture prepared in the step (2) at constant temperature;
(4) calcining the dried mixture obtained in the step (3) for 3-3.5 hours, and cooling to obtain an active component;
step two: preparation of copper-doped phosphomolybdic acid catalyst
(1) Mixing the active component prepared in the step one and TiO2Weighing the materials in proportion, putting the materials into a crucible filled with distilled water, and stirring the materials on a magnetic stirrer at a constant speed for 1 to 1.5 hours;
(2) drying the mixture obtained in the step (1) at a constant speed, and evaporating water to dryness;
(3) drying the mixture prepared in the step (2) at constant temperature;
(4) and (4) calcining the dried mixture in the step (3) for 3-3.5 h, and cooling to obtain the copper-doped phosphomolybdic acid low-temperature denitration catalyst.
Furthermore, in the first step, the mass of PEG is 0.5-1% of the mass of molybdenum phosphate, the molar ratio of Cu to Mo is (0-4) to 1, the mass ratio of CTAB to phosphomolybdic acid is (0-0.6) to 1, and the mass of the active component in the second step accounts for 5-15% of the total mass of the catalyst.
Furthermore, in the first step and the second step, the constant-speed stirring temperature of the magnetic stirrer is 25-30 ℃, the drying temperature on the magnetic stirrer is 85-90 ℃, the heating temperature of the drying box is 100-110 ℃, and the calcining temperature of the muffle furnace is 350-450 ℃.
Furthermore, the constant-speed stirring temperature of the magnetic stirrer is 25 ℃, the drying temperature on the magnetic stirrer is 85 ℃, the heating temperature of the drying box is 105 ℃, and the calcining temperature of the muffle furnace is 350 ℃.
Furthermore, the active component accounts for 10 percent of the mass of the catalyst in the step two (1).
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) the invention relates to a copper-doped phosphomolybdic acid low-temperature denitration catalyst, which adopts anatase TiO2As a carrier, phosphomolybdic acid, copper nitrate, polyethylene glycol (PEG) and a surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) are used as active components, and the coordination and the coaction of the components are used for regulating and controlling the surface acidity and the structural characteristics of the catalyst, SO that the surface acidity and the exposure of active sites of the catalyst are increased, the low-temperature denitration activity of the catalyst is improved, and the catalyst has certain SO resistance2And the steam poisoning performance is beneficial to the development of the application of the low-temperature flue gas denitration technology in the actual industrial production.
(2) The copper-doped phosphomolybdic acid low-temperature denitration catalyst provided by the invention takes phosphomolybdic acid and copper nitrate as active components, and the phosphomolybdic acid is a heteropoly acid with a Keggin structure, has more acid sites and active oxygen structures, and has strong surface acidity and redox performance, and meanwhile, the doping of a transition metal Cu atom can increase the amount of the active oxygen atoms in the phosphomolybdic acid to generate Cu+/Cu2+The denitration reaction being promoted by redox reactionThe method is beneficial to adsorbing NO molecules on the surface of the catalyst and enhancing the oxidation reduction and electron storage capacity of the catalyst.
(3) According to the copper-doped phosphomolybdic acid low-temperature denitration catalyst, the surfactant CTAB in the active component generates cationic CTA in water+Replacing H in hydroxyl on the surface of Cu metal atom+When the active component is calcined, the surfactant is oxidized and decomposed to become gas to be discharged, more L acid sites are left, and the aim of regulating the ratio of the catalyst B acid to the catalyst L acid can be achieved; CTAB can also reduce the bonding energy of lattice oxygen and improve the surface adsorption of oxygen OβIn a ratio of NO to NO2The conversion of the catalyst promotes the rapid SCR reaction, thereby promoting the low-temperature denitration activity of the catalyst; meanwhile, the addition of the polyethylene glycol effectively increases the degree of openness of the active component, enhances the adsorption capacity of the active component, and enables the active component to be better loaded on the carrier.
(4) The low-temperature denitration catalyst of copper-doped phosphomolybdic acid controls the molar ratio of Cu to Mo in the active component, the mass of the surfactant, the mass of the active component and TiO2The specific surface area of the catalyst further improves the catalytic activity and SO resistance of the catalyst under low temperature conditions2And water vapor poisoning ability, and in TiO2Is a carrier, and further increases the exposure of surface active sites.
(5) According to the preparation method of the copper-doped phosphomolybdic acid low-temperature denitration catalyst, the proportion of each reaction raw material and each reaction process parameter, such as stirring temperature, drying temperature, heating temperature, calcining temperature, stirring time and the like, are strictly controlled, so that the catalytic activity, sulfur resistance and water vapor resistance of the catalyst can be optimally matched, and the preparation process is simple, wide in raw material source, low in price, non-toxic and harmless, and high in low-temperature activity and certain sulfur resistance and water resistance; wherein when the active component accounts for 10 percent of the mass of the catalyst, the constant-speed stirring temperature of the magnetic stirrer is 25 ℃, the drying temperature on the magnetic stirrer is 85 ℃, the heating temperature of the drying box is 105 ℃, and the calcining temperature of the muffle furnace is 350 ℃, the catalytic activity of the catalyst can be ensuredThe performance and the denitration efficiency are optimized, and the SO resistance of the catalyst is realized2And the water vapor poisoning ability is improved to the maximum extent.
Detailed Description
For a further understanding of the present invention, reference will now be made to the following examples.
The copper-doped phosphomolybdic acid low-temperature denitration catalyst adopts anatase TiO2As a carrier, phosphomolybdic acid, copper nitrate, polyethylene glycol (PEG) and a surfactant Cetyl Trimethyl Ammonium Bromide (CTAB) are used as active components, the molar ratio of Cu to Mo in the active components is (0-4) to 1, the mass of the surfactant in the active components accounts for 0-60% of the mass of the phosphomolybdic acid, the mass of the active components in the catalyst accounts for 5-15% of the total mass of the catalyst, and anatase type TiO is anatase type2The specific surface area of (1) is 300-350m2/g。
The copper-doped phosphomolybdic acid low-temperature denitration catalyst is prepared by an impregnation method: firstly, taking phosphomolybdic heteropoly acid as an active precursor, adding auxiliary agents such as CTAB, copper nitrate, PEG and the like, stirring at a constant speed for reaction under the condition of water bath at 25 ℃, and drying, drying and calcining a reaction mixture to obtain an active component; finally, the active component is mixed with TiO2Adding distilled water into the carrier according to a certain proportion, stirring and mixing, drying and calcining to obtain the catalyst. The preparation method comprises the following steps:
the method comprises the following steps: preparation of the active ingredient
(1) Putting a certain amount of phosphomolybdic acid, copper nitrate, a surfactant CTAB and PEG into a crucible, adding distilled water to dissolve, and stirring for 1-1.5 hours at a constant speed on a magnetic stirrer, wherein the stirring temperature is 25-30 ℃;
(2) drying the mixture obtained in the step (1) on a magnetic stirrer at a constant speed, and evaporating water to dryness at the drying temperature of 85-90 ℃;
(3) placing the mixture prepared in the step (2) into a drying oven for drying at a constant temperature, wherein the heating temperature of the drying oven is 100-110 ℃;
(4) and (4) calcining the dried mixture in the step (3) in a muffle furnace at the temperature of 350-450 ℃ for 3-3.5 h, and cooling to obtain the active component.
Step two: preparation of copper-doped phosphomolybdic acid catalyst
(1) Mixing the active component prepared in the step one and TiO2Weighing the materials in proportion, putting the materials into a crucible filled with distilled water, and stirring the materials on a magnetic stirrer at a constant speed for 1 to 1.5 hours, wherein the stirring temperature is 25 to 30 ℃;
(2) drying the mixture obtained in the step (1) on a magnetic stirrer at a constant speed, and evaporating water to dryness at the drying temperature of 85-90 ℃;
(3) placing the mixture prepared in the step (2) into a drying oven for drying at a constant temperature, wherein the heating temperature of the drying oven is 100-110 ℃;
(4) and (4) calcining the dried mixture in the step (3) in a muffle furnace at the temperature of 350-450 ℃ for 3-3.5 h, and cooling to obtain the copper-doped phosphomolybdic acid low-temperature denitration catalyst.
The active component phosphomolybdic acid of the low-temperature denitration catalyst is a heteropoly acid with a Keggin structure, has more acid sites and active oxygen structures, has strong surface acidity and redox performance, and has larger specific surface area (the specific surface area is not less than 300 m)2Per g) of TiO2Is a carrier, and further increases the exposure of surface active sites.
Specifically, the analysis principle of the present invention is as follows:
NH in the gas phase during SCR denitration reaction
3First, the active acid sites (A) are adsorbed on the surface of the catalyst
Acid or Lewis acid) to form a dissociated adsorbate species-NH-in a transition state
2,-NH
2Further reacts with NO in the gas phase to form N
2And H
2And O. NH at 300-400 DEG C
3In the SCR reaction, the reaction mixture is heated,
NH adsorbed at the acid site
3Plays a main role; and at low temperature NH
3NH adsorbed at the Lewis acid site in the SCR reaction
3Plays a major role.
Through a great deal of experimental research, the inventor finds that the doping of the transition metal Cu can increase the amount of active oxygen atoms in phosphomolybdic acid to generate Cu+/Cu2+The oxidation reduction promotes the denitration reaction, so that NO molecules can be favorably adsorbed on the surface of the catalyst, Cu ions can replace hydrogen protons on the surface of phosphomolybdic acid in the reaction, and a Cu-O-Mo (copper-oxygen-molybdenum) heteroend bridged catalytic center is formed while the acid center is guided to be deviated to a low-temperature section by regulating the acid/L acid ratio of the catalyst B, so that the oxidation reduction and electron storage capacities of the catalyst are improved; surfactant CTAB produces cationic CTA in water+Replacing H in hydroxyl on the surface of Cu metal atom+When the active component is calcined, the surfactant is oxidized and decomposed to become gas to be discharged, more L acid sites are left, and the aim of regulating the ratio of the catalyst B acid to the catalyst L acid can be achieved; CTAB can also reduce the bonding energy of lattice oxygen and improve the surface adsorption of oxygen OβIn a ratio of NO to NO2To promote the rapid SCR reaction. Therefore, the catalyst provided by the invention has better low-temperature denitration activity.
Because a certain amount of SO is often included in industrial flue gas2,SO2Is an acid gas, occupies active sites by competitive adsorption on the surface of the catalyst and can sulfate active components to cause the activity of the catalyst to be reduced, SO the SO can be inhibited by enhancing the surface acidity of the catalyst2Adsorption and sulfation of the active component. In the preparation process of the catalyst, the phosphomolybdic heteropoly acid with stronger surface acidity (stronger than common inorganic oxygen acid) is used as one of the active components, and the surfactant CTAB and the doped metal Cu are added to regulate and control the surface acidity, SO that the SO resistance of the catalyst is improved2Poisoning properties.
The water vapor in the flue gas occupies active sites through competitive adsorption to cause low-temperature denitration catalysisYet another important factor is the reduced activity of the agent. Through research, the water molecules are found to have adsorption and desorption equilibrium on the surface of the catalyst at any temperature, and the percentage of the water molecules occupying the active sites on the surface of the catalyst is certain. The catalyst of the invention has larger specific surface area (the specific surface area is not less than 300 m) used in the preparation process2/g) anatase type TiO2As a carrier, the exposure of active sites on the surface of the catalyst is increased, the absolute number of denitration active sites of the catalyst in the presence of water vapor can be increased, and the water resistance of the catalyst is further improved.
The present invention will be further described with reference to the following examples.
Example 1
The method comprises the following steps: preparation of the active ingredient
Step one, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid) and 2g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 2: 1), putting the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 3.0g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 2
The method comprises the following steps: preparation of the active ingredient
Step one, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring for 1 hour on a magnetic stirrer at a constant speed, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.7g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 3
The method comprises the following steps: preparation of the active ingredient
Step one, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid) and a certain amount of copper nitrate (the molar ratio of Cu to Mo is controlled to be 4: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring for 1 hour on a magnetic stirrer at a constant speed, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.7g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 4
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.1g of surfactant CTAB (weighed according to 10 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.7g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; fourthly, putting the mixture dried in the third step into a muffleCalcining the mixture in a furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 5
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.2g of surfactant CTAB (weighed according to 20 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.8g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 6
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.4g of surfactant CTAB (weighed according to 40 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.7g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 7
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.2g of surfactant CTAB (weighed according to 20 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at constant temperature, and controlling the drying temperature to be 100 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 400 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 2.7g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; in the second step, the mixture obtained in the first step is stirred on a magnetic stirrer at a constant speedDrying, namely drying the water by distillation, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at constant temperature, and controlling the drying temperature to be 100 ℃; and fourthly, putting the mixture dried in the third step into a muffle furnace, calcining for 3 hours at 400 ℃, and cooling to obtain the catalyst.
Example 8
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.2g of surfactant CTAB (weighed according to 20 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 90 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 110 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 450 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.32g of active ingredient (10% by weight) and 3.2g of anatase TiO are weighed out2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 90 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 110 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 450 ℃ for 3h, and cooling to obtain the catalyst.
Example 9
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.005g of PEG (weighed according to 0.5 percent of the mass of the phosphomolybdic acid), 0.2g of surfactant CTAB (weighed according to 20 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1) and placing the mixture into a crucible, adding 40ml of distilled water for dissolving, and stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, wherein the stirring temperature is controlled to be 30 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to 87 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.3g of active ingredient (10% by weight) and 3g of anatase TiO are weighed2(specific surface area of not less than 300 m)2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 30 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to 87 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Example 10
The method comprises the following steps: preparation of the active ingredient
Firstly, weighing 1g of phosphomolybdic acid, 0.01g of PEG (weighed according to 1 percent of the mass of the phosphomolybdic acid), 0.6g of surfactant CTAB (weighed according to 60 percent of the mass of the phosphomolybdic acid) and 4.7658g of copper nitrate (the molar ratio of Cu to Mo is controlled to be 3: 1), adding 40ml of distilled water for dissolving, and stirring for 1 hour on a magnetic stirrer at a constant speed, wherein the stirring temperature is controlled to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, putting the mixture dried in the third step into a muffle furnace to calcine for 3 hours at the temperature of 450 ℃, and cooling to obtain the active component.
Step two: preparation of the catalyst
In a first step, 0.38g of active ingredient (15% by weight) and 2.55g of anatase TiO are weighed out2(specific surface area)Product is not less than 300m2/g) placing the mixture into a crucible, adding 40ml of distilled water for dissolving, stirring the mixture on a magnetic stirrer at a constant speed for 1 hour, and controlling the stirring temperature to be 25 ℃; step two, drying the mixture obtained in the step one on a magnetic stirrer at a constant speed, evaporating water to dryness, and controlling the drying temperature to be 85 ℃; thirdly, placing the mixture obtained in the second step into a drying box for drying at a constant temperature, and controlling the drying temperature to be 105 ℃; and fourthly, calcining the mixture dried in the third step in a muffle furnace at 350 ℃ for 3h, and cooling to obtain the catalyst.
Secondly, detecting the performance of the catalyst
Example 11
0.47g of the catalysts prepared in catalyst preparation examples 1 to 10 was weighed, respectively, and placed in fixed bed reactors having an inner diameter of 8mm, respectively, to test the denitration activity. During the test, high purity N is used2As carrier gas, controlling airspeed at 15000h-1Controlling the concentration of inlet NO to be 500ppm and NH3And NO in a molar ratio of 1, O2The volume concentration was 8%, and the test temperature range was 150 ℃ to 350 ℃, the results are shown in FIG. 1.
As can be seen from the activity test data in FIG. 1, there is no SO in the simulated flue gas2And steam at a temperature in the range of 200-350 ℃ using the catalyst NO of examples 1-10xThe conversion rates of (A) are all higher than 93%; wherein, the denitration rate of the catalyst in the implementation examples 5, 6 and 9 reaches more than 80% at 150 ℃, and can be stabilized at 100% at 200 ℃ and 300 ℃; among them, it can be seen from FIG. 1 that the denitration activity of the catalyst of example 5 is the best, NO at 150 ℃ isxThe conversion rate is 82 percent, and the denitration efficiency at 200-350 ℃ can be stabilized at 100 percent.
Example 12
0.47g of the catalyst prepared in catalyst preparation example 5 was weighed, respectively, and placed in fixed bed reactors having an inner diameter of 8mm, respectively, to obtain high-purity N2As carrier gas, controlling airspeed at 15000h-1Controlling the concentration of inlet NO to be 500ppm and NH3And NO in a molar ratio of 1, O2The volume concentration is 8%, the test temperature is 200 ℃, SO is examined2Concentration and steam to NOxInfluence of conversion rateAs listed in figure 2.
As can be seen from the data in FIG. 2, SO was present in the simulated flue gas2The catalyst in example 5 had a NOx conversion of greater than 92% at a concentration in the range of 100-550ppm and a water vapor concentration of 0. When simulating SO in flue gas2The catalyst NOx conversion in example 5 was higher than 95% at a concentration of 0 and a steam concentration in the range of 4-12% vol. When simulating SO in flue gas2Catalyst NO in example 5 at a concentration of 400ppm and a steam concentration of 8% volxThe conversion rate can be kept above 95% when the reaction is carried out for 1h, gradually decreases to about 50% along with the continuous reaction, and can be recovered to about 99% after the sulfur and water introduction is stopped for 3 h.
In conclusion, the copper-doped phosphomolybdic acid low-temperature denitration catalyst disclosed by the invention has higher low-temperature activity and excellent sulfur-resistant and water-resistant performances. Meanwhile, it should be noted that the catalyst prepared by adopting other embodiment of the invention has no SO resistance of the example 52Has good effect on mixing water vapor, but has SO resistance compared with the prior catalyst2And the water vapor effect are also of significant advantage.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.