阅读说明：本技术 Scr脱硝催化剂及其制备方法和应用 (SCR denitration catalyst and preparation method and application thereof ) 是由 周佳丽 马子然 王宝冬 马静 李歌 刘子林 孙琦 于 2019-01-17 设计创作，主要内容包括：本发明涉及SCR脱硝催化剂领域,具体涉及一种SCR脱硝催化剂及其制备方法和应用,该催化剂包括载体和负载在所述载体上的活性组分,所述活性组分包括V、Mo、W和可选的P、Si；以氧化物计的所述活性组分与所述载体的重量比为1：(5-40)；以催化剂的总量为基准,以氧化物计,V的含量为0.4-5重量％,Mo的含量为0.6-5重量％,W的含量为0.5-15重量％,P的含量为0-1重量％,Si的含量为0-1重量％。采用该方法制得的脱硝催化剂具有更强的催化氧化还原能力和表面酸性,且在低温下能够表现出更好的脱硝活性。(The invention relates to the field of SCR denitration catalysts, in particular to an SCR denitration catalyst and a preparation method and application thereof, wherein the catalyst comprises a carrier and active components loaded on the carrier, and the active components comprise V, Mo, W and optional P, Si; the weight ratio of the active component to the carrier calculated by oxide is 1: (5-40); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-5 wt%, the content of Mo is 0.6-5 wt%, the content of W is 0.5-15 wt%, the content of P is 0-1 wt%, and the content of Si is 0-1 wt%. The denitration catalyst prepared by the method has stronger catalytic oxidation reduction capability and surface acidity, and can show better denitration activity at low temperature.)

1. An SCR denitration catalyst, characterized in that the catalyst comprises a carrier and an active component supported on the carrier, the active component comprising V, Mo, W and optionally P, Si; the weight ratio of the active component to the carrier calculated by oxide is 1: (5-40); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-5 wt%, the content of Mo is 0.6-5 wt%, the content of W is 0.5-15 wt%, the content of P is 0-1 wt%, and the content of Si is 0-1 wt%.

2. The catalyst of claim 1, wherein the weight ratio of the active component to the support, calculated as oxides, is 1: (7-35); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-3.5 wt%, the content of Mo is 0.7-4.5 wt%, the content of W is 2-10 wt%, the content of P is 0-0.5 wt%, and the content of Si is 0-0.6 wt%.

3. The catalyst according to claim 1 or 2, wherein the molar ratio of V and Mo in the catalyst is 1: (0.4-1.85), preferably 1: (0.6-1).

4. A catalyst according to any one of claims 1 to 3, wherein at least one of the active components is introduced into the catalyst in the form of a heteropolyacid;

preferably, the heteropoly acid is Keggin type heteropoly acid and/or Dawson type heteropoly acid;

more preferably, the heteropoly acid is a Keggin type heteropoly acid and a Dawson type heteropoly acid, and the weight ratio of the Keggin type heteropoly acid to the Dawson type heteropoly acid is 1: (0.4-4).

5. The catalyst of any one of claims 1-4, wherein the support is TiO₂。

6. The method of preparing the SCR denitration catalyst of any one of claims 1 to 5, comprising:

the carrier is impregnated with a solution containing an active component precursor and then calcined.

7. The production method according to claim 6, wherein the active component precursor comprises a vanadium-containing compound and a molybdenum-containing heteropoly acid, the support is a titanium tungsten powder, or the active component precursor comprises a molybdenum-containing heteropoly acid or a water-soluble salt thereof, a vanadium-containing compound, and a tungsten-containing heteropoly acid or a water-soluble salt thereof, or the active component precursor comprises a vanadium-containing compound and a molybdenum-containing heteropoly acid, or the active component precursor comprises a tungsten-containing heteropoly acid and a molybdenum-containing heteropoly acid containing vanadium, or the active component precursor comprises a molybdenum-containing heteropoly acid and a tungsten-containing heteropoly acid containing vanadium;

preferably, the vanadium-containing compound is selected from at least one of ammonium metavanadate, vanadium oxalate and vanadyl oxalate;

preferably, the molybdic heteropolyacid is selected from phosphomolybdic acid;

preferably, the tungstocontaining heteropolyacid is selected from phosphotungstic acid and/or silicotungstic acid;

preferably, the molybdenum-containing vanadium-containing heteropolyacid is selected from phosphomolybdic acid;

preferably, the tungsten-containing vanadium-containing heteropolyacid is selected from phosphotungstic vanadic acid;

preferably, the molybdenum-containing tungstopolyacid is selected from phosphotungstomolybdic acid.

8. The production method according to claim 6 or 7, wherein the firing conditions include: the temperature is 450-600 ℃, and the time is 2-5 h;

preferably, the roasting comprises a stage 1), a stage 2) and a stage 3), wherein the roasting temperature of the stage 1) is 100-150 ℃, and the roasting time is 0.5-2 h; the roasting temperature of the stage 2) is 280-320 ℃, and the roasting time is 0.5-2 h; the roasting temperature of the stage 3) is 450-600 ℃, and the roasting time is 2-5 h;

preferably, the ramp rates for ramp-up to stage 1), stage 2), and stage 3) are each independently 1-5 deg.C/min.

9. The SCR denitration catalyst produced by the production method according to any one of claims 6 to 8.

10. Use of the SCR denitration catalyst of any one of claims 1 to 5 and 9 for low temperature denitration.

Technical Field

The invention relates to the field of SCR denitration catalysts, and particularly relates to an SCR denitration catalyst and a preparation method and application thereof.

Background

NH₃SCR technology has proven to be the most effective denitration technology and is most widely used, and the most central part of the technology is the development of denitration catalysts. V which is commercially available on the market at present₂O₅-WO₃(MoO₃)/TiO₂The catalyst shows excellent denitration performance at the temperature of 300-400 ℃, however, under the condition of low-load operation in 60% of domestic power plants, when the unit is in peak-shaving low-load operation, the flue gas temperature is reduced to be below 300 ℃, the denitration activity of the traditional vanadium-based catalyst is reduced, ammonia escape is increased, and viscous ammonium bisulfate is easy to generate to block an air preheater.

Aiming at the problems of a denitration system of a thermal power plant during low-load operation, the ministry of environmental protection of China issues a written requirement, and the thermal power plant must realize standard emission under any load operation working condition. The main two solutions for improving the low-load denitration efficiency of the unit are as follows: 1) a coal economizer is improved, and the temperature of flue gas is increased; 2) the wide temperature difference denitration catalyst is developed, and the low-temperature denitration activity of the catalyst is improved. Reform transform the economizer and have the cost great, shortcomings such as construction cycle length, if can develop novel wide temperature denitration catalyst, have important meaning to solving the operation of the wide load deNOx systems of thermal power plant.

CN104801349A discloses a heteropoly acid doped V₂O₅-WO₃/TiO₂A medium-low temperature SCR denitration catalyst which is V₂O₅And Dawson type phosphomolybdovanadic acid as active component, WO₃As auxiliaries, TiO₂As carrier, glass fibers GF are used as shaping aid. The catalyst has a certain low-temperature SCR denitration effect. However, the temperature of the flue gas after desulfurization is reduced, and the activity of the SCR denitration catalyst prepared by the method cannot meet the flue gas denitration efficiency.

CN106582739A discloses a heteropoly acid doped cerium oxide SCR denitration catalyst which is made of anatase TiO₂As a carrier, cerium oxide CeO supported thereon₂And a phosphotungstic acid HPW mixture is used as an active component, and glass fiber is used as a forming auxiliary agent. But CeO₂Susceptible to SO₂And NO is easily generated, and the flue gas denitration efficiency at low temperature cannot be satisfied.

However, the existing denitration catalyst cannot be used for effectively denitrating flue gas with lower temperature after desulfurization.

Disclosure of Invention

The invention aims to solve the problems that the catalyst for SCR in the prior art cannot meet the denitration efficiency and has poor low-temperature denitration efficiency, and provides an SCR denitration catalyst, a preparation method and application thereof.

In order to achieve the above object, a first aspect of the present invention provides an SCR denitration catalyst, wherein the catalyst comprises a support and an active component supported on the support, the active component comprising V, Mo, W, and optionally P, Si; the weight ratio of the active component to the carrier calculated by oxide is 1: (5-40); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-5 wt%, the content of Mo is 0.6-5 wt%, the content of W is 0.5-15 wt%, the content of P is 0-1 wt%, and the content of Si is 0-1 wt%.

The second aspect of the present invention provides a preparation method of an SCR denitration catalyst, including: the carrier is impregnated with a solution containing an active component precursor and then calcined.

The invention also provides a preparation method of the SCR denitration catalyst.

A fourth aspect of the present invention provides a use of the SCR denitration catalyst of the first and third aspects described above in low-temperature denitration.

The active components of the catalyst prepared by the method mainly comprise V, Mo and W which have synergistic effect, and under the condition that the components meet the relationship, the catalyst has better denitration reduction capability at low temperature, has wider denitration active window and can react with NH₃Has strong adsorption capacity, NO at high space velocity_xHigher conversion of (2), N₂The selectivity is high.

Drawings

FIG. 1 is an XRD diffractogram of catalysts S1-S4 prepared in the examples.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides an SCR denitration catalyst, wherein the catalyst comprises a carrier and active components loaded on the carrier, wherein the active components comprise V, Mo, W and optionally P, Si; the weight ratio of the active component to the carrier calculated by oxide is 1: (5-40); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-5 wt%, the content of Mo is 0.6-5 wt%, the content of W is 0.5-15 wt%, the content of P is 0-1 wt%, and the content of Si is 0-1 wt%.

In the invention, active components V, Mo and W and optional P, Si are loaded on the carrier of the catalyst, and under the condition that the active components and the carrier meet the conditions, the prepared catalyst has a wider temperature activity window, the denitration activity of the catalyst is kept not to be reduced under a high temperature condition, and the catalyst still has better denitration catalytic activity under a low temperature condition (200-. And at high airspeed (up to 80000 h)^-1) Lower NO_xThe conversion rate of the catalyst can reach more than 68 percent, N₂The selectivity is kept above 99%.

In order to further improve the low-temperature denitration performance of the catalyst and enhance NO_xPreferably, the weight ratio of the active component to the support, calculated as oxides, is 1: (7-35); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-3.5 wt%, the content of Mo is 0.7-4.5 wt%, the content of W is 2-10 wt%, the content of P is 0-0.5 wt%, and the content of Si is 0-0.6 wt%.

Further preferably, the weight ratio of the active component to the carrier, calculated as oxides, is 1: (10-30); based on the total amount of the catalyst, calculated by oxide, the content of V is 0.4-3 wt%, the content of Mo is 0.75-3.2 wt%, the content of W is 0.9-6.3 wt%, and the content of P is 0.05-0.4 wt%.

In order to further improve the low-temperature denitration activity of the catalyst and improve the sulfur resistance, water resistance and N resistance of the catalyst₂Selectivity, preferably, the molar ratio of V and Mo in the catalyst is 1: (0.4-1.85), preferably 1: (0.6-1).

The introduction of the active component is not particularly limited as long as the catalyst having the above-mentioned kind and content of the active component can be obtained, and the invention is intended to further widen the active temperature window of the catalyst, improve the denitration efficiency at low temperature, and enhance the sulfur resistance, water resistance and N resistance of the catalyst₂Optionally, at least one of the active components is introduced into the catalyst in the form of a heteropolyacid. In the present invention, "at least one of the active components is introduced into the catalyst in the form of a heteropoly acid" means that a precursor of at least one of the active components is a heteropoly acid, and the heteropoly acid is converted into a corresponding active component oxide by calcination.

In the invention, one of the active components may be introduced into the catalyst in the form of a heteropoly acid, two of the active components may be introduced into the catalyst in the form of a heteropoly acid, three of the active components may be introduced into the catalyst in the form of a heteropoly acid, four of the active components may be introduced into the catalyst in the form of a heteropoly acid, or all (five) of the active components may be introduced into the catalyst in the form of a heteropoly acid. Some heteropoly acids contain at least two active component elements, in which case, at least two of the active component elements can be introduced simultaneously by using one heteropoly acid, for example, using phosphotungstic vanadic acid as a precursor, and three active component elements of phosphorus, tungsten and vanadium can be introduced simultaneously into the catalyst. The person skilled in the art can, on the basis of the above, choose the heteropolyacid appropriately to introduce the active component into the catalyst.

According to the present invention, preferably, the heteropoly acid is a Keggin-type heteropoly acid and/or a Dawson-type heteropoly acid.

More preferably, the heteropoly acid is a Keggin type heteropoly acid and a Dawson type heteropoly acid, and the weight ratio of the Keggin type heteropoly acid to the Dawson type heteropoly acid is 1: (0.4-4). In the research process, the inventor of the invention finds that the Keggin type heteropoly acid and the Dawson type heteropoly acid are used in a matched mode to introduce active components into the catalyst, the prepared catalyst has larger adsorption capacity to ammonia, and the low-temperature denitration activity of the catalyst can be greatly improved.

In the present invention, the Keggin-type heteropoly acid is preferably selected from phosphotungstic acid (H)₆P₂W₂₄O₈₀) Silicotungstic acid (H)₄SiW₁₂O₄₀) And phosphomolybdic acid (H)₃PMo₁₂O₄₀) At least one of; the heteropoly acid of Dawson type is preferably selected from phosphomolybdovanadic acid (H)₈P₂Mo₁₆V₂O₆₂) Phosphotungstic vanadic acid (H)₇P₂W₁₇VO₆₂) And phosphotungstomolybdic acid (H)₆P₂W₉Mo₉O₆₂) At least one of (1). If the added heteropoly-acid does not contain Mo, Mo can be introduced by a salt containing Mo element, for example, by adding ammonium heptamolybdate to the solution to introduce Mo as an active component.

In order to further improve the dispersion uniformity of the active component in the catalyst on the carrier, preferably, the carrier is TiO₂。

In the invention, in the process of preparing the catalyst, W can be taken as an active component and introduced into the carrier in the form of heteropoly acid, or can be introduced through salt containing W element, or can be introduced into the carrier TiO₂Replacing titanium tungsten powder and then introducing other active components. Namely, the introduction mode of W in the active component is at least one of heteropolyacid, salt containing W element and titanium tungsten powder.

The XRD pattern of the SCR denitration catalyst prepared by the invention is shown in figure 1, and the diffraction peak position of the prepared catalyst is the same as that of TiO₂The diffraction peak of the catalyst is corresponding to that of other oxides or heteropoly acid, and no other oxide or heteropoly acid is found, so that the active components of all the catalysts are well dispersed in TiO₂Of (2) is provided.

According to an embodiment of the present invention, the SCR denitration catalyst is formed of TiO₂And supported on TiO₂The active component composition above, wherein the active components are W, Mo, V and P; preferably, the content of Ti is 88-97 wt%, the content of W is 0.9-6.3 wt%, the content of Mo is 0.75-3.2 wt%, the content of V is 0.4-3 wt%, and the content of P is 0.05-0.4 wt%, calculated as oxide, based on the total amount of the catalyst.

According to another embodiment of the present invention, the SCR denitration catalyst is formed of TiO₂And supported on TiO₂The above active ingredients, wherein the active ingredients are W, Mo and V; preferably, the content of Ti is 90-97 wt%, the content of W is 1-6 wt%, the content of Mo is 1-3 wt%, and the content of V is 0.8-3 wt%, calculated as oxide, based on the total amount of the catalyst.

In TiO₂The active component composed of the metal oxide is loaded on the catalyst, and W, Mo and V are mutually cooperated and are matched with TiO in the preparation process of the catalyst₂The prepared SCR catalyst has higher catalytic activity, the ammonia adsorption amount of the catalyst can reach 318-_xThe conversion rate can reach more than 68 percent, N₂The selectivity can reach more than 99 percent.

The second aspect of the present invention provides a preparation method of an SCR denitration catalyst, including: the carrier is impregnated with a solution containing an active component precursor and then calcined.

According to the invention, the SCR denitration catalyst prepared by the method can effectively improve the low-temperature denitration activity of the catalyst and enhance the sulfur resistance, water resistance and N resistance of the catalyst₂And (4) selectivity.

In the present invention, the active component precursor is not particularly limited, and is a substance that can be converted into the active component oxide by the subsequent firing, and includes, but is not limited to, heteropolyacid, and a water-soluble salt containing an active component element.

In order to further increase the ammonia adsorption amount of the SCR denitration catalyst and increase the low-temperature denitration activity of the catalyst, preferably, at least one of the active component precursors is a heteropoly acid, and more preferably, the heteropoly acid is a Keggin-type heteropoly acid and/or a Dawson-type heteropoly acid.

According to the invention, the active component precursor comprises a vanadium-containing compound and a molybdenum-containing heteropoly acid, the carrier is titanium tungsten powder, or the active component precursor comprises a molybdenum-containing heteropoly acid or a water-soluble salt containing molybdenum, a vanadium-containing compound and a tungsten-containing heteropoly acid or a water-soluble salt containing tungsten, or the active component precursor comprises a vanadium-containing compound and a molybdenum-containing heteropoly acid, or the active component precursor comprises a tungsten-containing heteropoly acid and a molybdenum-containing heteropoly acid containing vanadium, or the active component precursor comprises a molybdenum-containing heteropoly acid and a tungsten-containing heteropoly acid containing vanadium.

Preferably, the active component precursor comprises a tungstenic heteropoly acid and a molybdenic vanadium-containing heteropoly acid, or the active component precursor comprises a molybdenic heteropoly acid and a tungstenic vanadium-containing heteropoly acid.

Preferably, the vanadium-containing compound is selected from at least one of ammonium metavanadate, vanadium oxalate and vanadyl oxalate;

preferably, the molybdic heteropolyacid is selected from phosphomolybdic acid;

preferably, the tungstocontaining heteropolyacid is selected from phosphotungstic acid and/or silicotungstic acid;

preferably, the molybdenum-containing vanadium-containing heteropolyacid is selected from phosphomolybdic acid;

preferably, the tungsten-containing vanadium-containing heteropolyacid is selected from phosphotungstic vanadic acid;

preferably, the molybdenum-containing tungstopolyacid is selected from phosphotungstomolybdic acid.

In the present invention, if the active component precursor includes a vanadium-containing compound, it is preferable to use a co-solvent, which is a conventional choice in the art, such as monoethanolamine, mixed with the vanadium-containing compound at 60 to 80 ℃ for the purpose of dissolution of the vanadium-containing compound when preparing the vanadium-containing solution.

In the invention, the carrier can be titanium dioxide or titanium tungsten powder. If the active component precursor can provide the active component tungsten, the carrier can be titanium dioxide and/or titanium tungsten powder. If the active component precursor can not provide the active component tungsten, the carrier can be selected from titanium tungsten powder.

In the present invention, the carrier may be subjected to a pre-drying treatment before impregnation, and the pre-drying conditions include: the temperature is 100-120 ℃, and the time is 3-5 h.

The impregnation can be carried out by means of techniques customary in the art, and can be carried out, for example, at ambient temperature (25 ℃) for 2 to 24 hours.

The concentration and volume of the solution containing the active component precursor can be determined by the water absorption of the carrier and the content of each active component in the prepared catalyst. The present invention will be described in detail herein, which can be obtained by a person skilled in the art by means of conventional techniques.

According to a particular embodiment of the invention, the preparation method further comprises a drying step before carrying out the roasting. Wherein the drying conditions may include: the temperature is 90-100 ℃ and the time is 3-5 h.

In order to further improve the molding stability of the catalyst and enhance the low-temperature denitration performance of the catalyst, preferably, the calcination conditions include: the temperature is 450-600 ℃, and the time is 2-5 h.

Further preferably, the roasting comprises a stage 1), a stage 2) and a stage 3), wherein the roasting temperature of the stage 1) is 100-; the roasting temperature of the stage 2) is 280-320 ℃, and the roasting time is 0.5-2 h; the roasting temperature of the stage 3) is 450-600 ℃, and the roasting time is 2-5 h. Specifically, the temperature rise rates of the temperature rise to the stage 1), the stage 2), and the stage 3) are each independently 1 to 5 ℃/min. In the present invention, the temperature increase rate in the range from room temperature to stage 1), stage 1) to stage 2), and stage 2) to stage 3) is not particularly limited, and may be, for example, 1 to 5 ℃/min independently of each other.

According to the invention, the SCR denitration catalyst prepared by the method can effectively improve the low-temperature reduction performance of the SCR denitration catalyst and improve the flue gas denitration efficiency of the SCR catalyst.

The invention also provides a preparation method of the SCR denitration catalyst.

According to the invention, the catalyst prepared by the method can be used for denitration treatment of desulfurized flue gas, and the catalyst still has a good denitration effect at low temperature.

The invention provides an application of the SCR denitration catalyst in low-temperature denitration.

In the invention, the SCR denitration catalyst prepared by the method can be used for denitration treatment of flue gas, particularly denitration treatment of flue gas subjected to desulfurization treatment. The SCR denitration catalyst prepared by the invention is used for denitration treatment of flue gas, the ammonia adsorption amount reaches over 315 mu mol/g, and the high airspeed (80000 h)^-1) NO at 200-_xThe conversion rate of the catalyst can still reach more than 68 percent, N₂The selectivity is kept above 99%.

The present invention will be described in detail below by way of examples.

"room temperature" in the following examples and comparative examples means 25 ℃.

The molecular formula of phosphotungstic acid in the raw material is H₆P₂W₂₄O₈₀Phosphomolybdic acid of formula H₃PMo₁₂O₄₀The molecular formula of phosphomolybdic acid is H₈P₂Mo₁₆V₂O₆₂The molecular formula of the phosphotungstic acid is H₇P₂W₁₇VO₆₂The molecular formula of the phosphotungstomolybdic acid is H₆P₂W₉Mo₉O₆₂Ammonium metavanadate having a molecular formula of NH₄VO₃Ammonium heptamolybdate has the molecular formula of (NH)₄)₆Mo₇O₂₄·4H₂O。