Arsenic and alkali poisoning resistant denitration catalyst and preparation method thereof

Abstract

This invention relates to the field of denitrification catalyst technology, and in particular to an arsenic- and alkali-poisoning-resistant denitrification catalyst and its preparation method. The denitrification catalyst comprises: a support, an active component, and a co-catalyst; the mass ratio of the active component to the support is (3-15):100; the mass ratio of the co-catalyst to the support is (3-8):100; the support comprises: calcium-based bentonite, attapulgite, and nano-cerium oxide; the active component is an oxide of vanadium, chromium, samarium, or niobium; and the co-catalyst is one or more oxides of molybdenum, tungsten, or praseodymium. This invention prepares a multi-component mesoporous composite oxide denitrification catalyst with excellent resistance to arsenic and alkali metal poisoning through multiple steps, solving the problem of poor arsenic and alkali resistance in traditional denitrification catalysts. It is suitable for nitrogen oxide emission control under flue gas conditions in coal-fired power plants, biomass boilers, and the glass industry.

Description

Technical Field

[0001] This invention relates to the field of denitrification catalyst technology, and in particular to a denitrification catalyst resistant to arsenic and alkali poisoning and its preparation method. Background Technology

[0002] Arsenic in coal, including organic arsenic, arsenic pyrite, and arsenic sulfide, is converted into gaseous As₂O₃ during combustion. When this arsenic deposits on the surface of denitrification catalysts, it not only covers the active sites of the catalyst but also reduces the catalyst's reduction performance and surface acidity, leading to significant deactivation of the catalyst. If the mass fraction of arsenic in the coal exceeds 3 × 10⁻⁶, the denitrification process can further deactivate the catalyst. -6 The lifespan of SCR catalysts will be reduced by about 30%. In thermal power plants in Inner Mongolia and Northeast my country, the coal mines are mostly high-arsenic coal, with arsenic content exceeding 25 μg / g, which is classified as grade IV arsenic coal. In some power plants, the arsenic content is as high as 90 μg / g, far exceeding the standard.

[0003] In recent years, with changes in the international situation and a sharp rise in coal prices, competition among coal-fired power plants has intensified. To reduce power generation costs, co-firing has become an inevitable requirement for the development of coal-fired power plants. The raw materials used for co-firing mainly include low-grade coal, sludge, and biomass, which leads to a significant increase in the alkali metal content in flue gas fly ash. Meanwhile, flue gas fly ash from non-power sectors generally contains large amounts of alkali metals. Denitrification catalysts placed in a highly alkaline flue gas environment may become deactivated within a short period due to alkali metal poisoning. Therefore, developing denitrification catalysts with synergistic resistance to arsenic and alkali metal poisoning is of great significance.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide an arsenic- and alkali-resistant denitrification catalyst and its preparation method, which can solve the problem of poor arsenic and alkali resistance of traditional denitrification catalysts.

[0006] In a first aspect, the present invention provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst; the mass ratio of the active component to the support is (3-15):100; the mass ratio of the co-catalyst to the support is (3-8):100; the support comprises: calcium-based bentonite, attapulgite, and nano-cerium oxide; the active component is an oxide of vanadium, chromium, samarium, or niobium; and the co-catalyst is one or more oxides of molybdenum, tungsten, or praseodymium.

[0007] In this invention, by controlling the mass ratio, calcination temperature, and number of cleaning cycles of the three carriers—calcined bentonite, attapulgite, and nano-cerium oxide—under the action of a modifier, a reasonable cerium-to-calcium ratio is maintained in the mesoporous material framework through pore expansion and ion replacement. This inhibits the adsorption and deposition of As2O3 and alkali metals on the catalyst surface, thereby improving the catalyst's resistance to arsenic and poisoning. Among these, cerium, calcium, samarium, and niobium can preferentially fix arsenic and alkali metals, inhibiting the poisoning of other components by arsenic and alkali metals. This allows the catalyst to maintain excellent denitrification activity for a long time in high-arsenic and high-alkali flue dust environments, and it can be widely used in coal-fired power plants, biomass boilers, the glass industry, and other applications.

[0008] Preferably, the mass ratio of the active component to the carrier is any one of 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, and 15:100.

[0009] Preferably, the mass ratio of the co-catalyst to the support is any one of 3:100, 4:100, 5:100, 6:100, 7:100, and 8:100.

[0010] Preferably, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide in the carrier is 100:(10-30):(5-30); more preferably, it is any one of 100:18:12, 100:10:5, 100:30:30, 100:10:30, or 100:28:6.

[0011] Preferably, the calcium content in calcium-based bentonite is 5%.

[0012] Preferably, the carrier is a modified carrier treated with a modifier, the modifier comprising: modifier E, modifier F and modifier G; modifier E is any one of hexadecyl dimethyl benzyl ammonium bromide and hexadecyl dimethyl benzyl ammonium chloride; modifier F is any one of octadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium chloride; and modifier G is titanium chloride.

[0013] Preferably, the mass ratio of the oxides of vanadium, chromium, samarium and niobium in the active components is 10:(0.5-5):(0.1-2):(0.1-2); more preferably, it is any one of 10:3:0.5:0.8, 10:0.5:0.1:0.1, 10:5:2:2, 10:5:2:0.2, and 10:0.6:0.1:1.8.

[0014] Preferably, the co-catalyst comprises two or three oxides of molybdenum, tungsten, and praseodymium; the mass ratio of the oxides of molybdenum, tungsten, and praseodymium is 1:(0-1):(0.5-3).

[0015] Furthermore, the co-catalyst is an oxide of molybdenum and praseodymium, and the mass ratio of the molybdenum and praseodymium oxides is any one of 1:0.5, 1:1, 1:2, and 1:3.

[0016] Furthermore, the co-catalyst is an oxide of molybdenum, tungsten, or praseodymium, wherein the mass ratio of the molybdenum, tungsten, or praseodymium oxide is any one of 1:0.5:3, 1:1:1, 1:0.1:2, or 1:0.8:0.5.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0018] S1. Mix calcium-based bentonite and attapulgite evenly, and then calcine to obtain substance A.

[0019] Preferably, calcium-based bentonite and attapulgite are mixed evenly and calcined at 500-650℃ for 5-10 hours to obtain substance A.

[0020] S2. Mix the substance A obtained in step S1 with nano-cerium oxide evenly, impregnate it in a modifier solution, and calcine to obtain substance B.

[0021] Preferably, the substance A obtained in step S1 is mixed evenly with nano-cerium oxide, impregnated in a modifier solution, reacted at 20-80°C for 8-12 hours, washed with deionized water until the pH is 6-8, dried at 30-80°C for 8-15 hours, and calcined at 300-450°C for 3-6 hours to obtain substance B.

[0022] Preferably, in step S2, the modifier solution includes: modifier E, modifier F, and modifier G: modifier E is any one of hexadecyl dimethyl benzyl ammonium bromide and hexadecyl dimethyl benzyl ammonium chloride; modifier F is any one of octadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium chloride; and modifier G is titanium chloride.

[0023] Preferably, in step S2, the mass ratio of substance A to nano-cerium oxide, modifier E, modifier F, and modifier G is 100:(1-2):(0.1-0.5):(0.05-0.3); more preferably, it is 100:1.6:0.3:0.2, 100:1:0.1:0.05, 100:2:0.5:0.3, 100:1:0.15:0.2, or 100:2:0.45:0.06.

[0024] S3. Immerse the substance B obtained in step S2 into a mixed solution of active component precursors, transfer it into a reaction vessel for calcination, and grind it to obtain substance C.

[0025] Preferably, the substance B obtained in step S2 is immersed in a mixed solution of active component precursors, transferred to a polytetrafluoroethylene reactor, reacted at 100-180°C for 2-6 hours, dried at 50-80°C for 3-5 hours, calcined at 450-650°C for 3-6 hours, and ground to a fineness of 120 mesh or higher to obtain substance C.

[0026] Preferably, in step S3, the active component precursor mixture solution includes: precursors of vanadium, chromium, samarium, and niobium; the precursor of vanadium is any one of ammonium metavanadate and vanadium oxysulfate; the precursor of chromium is any one of chromium nitrate, chromium chloride, and chromium sulfate; the precursor of samarium is any one of samarium nitrate, samarium sulfate, and samarium chloride; and the precursor of niobium is niobium chloride.

[0027] S4. Add the substance C obtained in step S3 to the mixed solution of the catalyst precursor, transfer it to a reaction vessel for calcination, and grind it to obtain substance D.

[0028] Preferably, the substance C obtained in step S3 is added to the mixed solution of the catalyst precursor, transferred to a polytetrafluoroethylene reactor, reacted at 60-100°C for 12-36 hours, dried at 80-120°C for 3-5 hours, calcined at 300-400°C for 5-8 hours, and ground to a fineness of 120 mesh or higher to obtain substance D.

[0029] Preferably, in step S4, the catalyst precursor mixture includes precursors of molybdenum, tungsten, and praseodymium; the precursor of molybdenum is ammonium molybdate; the precursor of tungsten is any one of ammonium metatungstate and ammonium paratungstate; and the precursor of praseodymium is any one of praseodymium nitrate, praseodymium sulfate, and praseodymium chloride.

[0030] This invention employs a multi-step preparation process to enable the composite oxides of active components vanadium, chromium, samarium, and niobium to synergistically interact with the support, thereby improving the catalyst's reduction and acid performance. Through secondary deposition, the additives effectively protect the active components and inhibit the catalyst's adsorption of As2O3 and alkali metals. As a result, the prepared multi-component mesoporous composite oxide denitration catalyst maintains high denitration activity while exhibiting good resistance to arsenic and alkali poisoning, as well as high N2 selectivity.

[0031] S5. The substance D obtained in step S4 is treated under a reducing atmosphere and then under an oxidizing atmosphere to obtain an arsenic-resistant and alkali-resistant denitrification catalyst.

[0032] Preferably, the substance D obtained in step S4 is treated in a reducing atmosphere at 350-550°C for 1-5 hours, and then in an oxidizing atmosphere at 450-650°C for 2-8 hours to obtain an arsenic-resistant and alkali-resistant denitrification catalyst.

[0033] Preferably, in step S5, the reducing atmosphere is an H2-Ar mixture, more preferably a 5-15% H2-Ar mixture; the oxidizing atmosphere is air.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) In this invention, calcium-based bentonite, attapulgite and nano-cerium oxide are three carriers. Under the action of the modifier, through pore expansion and ion replacement, the reasonable ratio of cerium and calcium in the mesoporous material skeleton is maintained, which inhibits the adsorption and deposition of As2O3 and alkali metals on the catalyst surface and improves the catalyst's resistance to arsenic and poisoning.

[0036] (2) The present invention uses a multi-step preparation process to enable the active components vanadium, chromium, samarium and niobium composite oxides to work synergistically with the support, thereby improving the reduction performance and acid performance of the catalyst. Through secondary deposition, the additives can effectively protect the active components and inhibit the adsorption of As2O3 and alkali metals by the catalyst. The resulting multi-component mesoporous composite oxide denitration catalyst has good resistance to arsenic and alkali poisoning while maintaining high denitration activity, and also has high N2 selectivity.

[0037] (3) In this invention, cerium, calcium, samarium and niobium can preferentially fix arsenic and alkali metals and inhibit the poisoning of other components by arsenic and alkali metals;

[0038] (4) This invention can synergistically poison the catalyst with arsenic and alkali metals, and can maintain excellent denitrification activity for a long time in high arsenic and high alkali dust environments. It can be widely used in coal-fired power plants, biomass boilers, glass industry, etc. Detailed Implementation

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0040] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst, wherein:

[0044] The mass ratio of the active component to the carrier is 8:100;

[0045] The mass ratio of the catalyst to the support is 100.

[0046] In the carrier, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide is 100:18:12;

[0047] The calcium content in calcium-based bentonite is 5%;

[0048] In the active components, the mass ratio of oxides of vanadium, chromium, samarium, and niobium is 10:3:0.5:0.8;

[0049] In the co-catalyst, the mass ratio of the oxides of molybdenum, tungsten, and praseodymium is 1:0.5:3.

[0050] This embodiment also provides a method for preparing an arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0051] S11. Mix calcium-based bentonite and attapulgite evenly, and calcine at 530℃ for 7.5 hours to obtain substance A.

[0052] S12. Mix the substance A obtained in step S11 with nano-cerium oxide evenly, impregnate it in a solution of hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride modifier, react at 55°C for 8 hours, wash with deionized water until pH is 7, dry at 65°C for 12 hours, and calcine at 380°C for 5 hours to obtain substance B.

[0053] The mass ratio of the carrier (substance A and nano-cerium oxide), hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride is 100:1.6:0.3:0.2.

[0054] S13. The substance B obtained in step S12 is immersed in a mixed solution of vanadium oxysulfate, chromium nitrate, samarium sulfate and niobium chloride, transferred to a polytetrafluoroethylene reactor and reacted at 120°C for 3 hours. After drying at 60°C for 4 hours, calcining at 550°C for 3 hours, and grinding to a fineness of 120 mesh or higher, substance C is obtained.

[0055] S14. Add the substance C obtained in step S13 to a mixed solution of ammonium molybdate, ammonium metatungstate, and praseodymium sulfate, transfer it to a polytetrafluoroethylene reactor, react at 85°C for 22 hours, dry at 100°C for 4.5 hours, calcine at 350°C for 6 hours, and grind it to a fineness of 120 mesh or higher to obtain substance D.

[0056] S15. The substance D obtained in step S14 is treated at 460℃ in an 8% H2-Ar mixed atmosphere for 3.5h, and then oxidized at 550℃ for 6h to obtain an arsenic-resistant and alkali-resistant multi-component mesoporous composite oxide denitrification catalyst.

[0057] Example 2

[0058] This embodiment provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst, wherein:

[0059] The mass ratio of active component to carrier is 3:100;

[0060] The mass ratio of the catalyst to the support is 3:100;

[0061] In the carrier, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide is 100:10:5;

[0062] The calcium content in calcium-based bentonite is 5%;

[0063] In the active components, the mass ratio of oxides of vanadium, chromium, samarium, and niobium is 10:0.5:0.1:0.1;

[0064] In the co-catalyst, the mass ratio of the oxides of molybdenum, tungsten, and praseodymium is 1:1:1.

[0065] This embodiment also provides a method for preparing an arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0066] S21. Mix calcium-based bentonite and attapulgite evenly, and calcine at 650℃ for 5 hours to obtain substance A.

[0067] S22. Mix the substance A obtained in step S21 with nano-cerium oxide evenly, impregnate it in a solution of hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride modifier, react at 20°C for 12 hours, wash with deionized water until pH is 6, dry at 30°C for 8 hours, and calcine at 300°C for 3 hours to obtain substance B;

[0068] The mass ratio of the carrier (substance A and nano-cerium oxide), hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride is 100:1:0.1:0.05.

[0069] S23. The substance B obtained in step S22 is immersed in a mixed solution of ammonium metavanadate, chromium nitrate, samarium nitrate and niobium chloride, transferred to a polytetrafluoroethylene reactor and reacted at 100°C for 2 hours, dried at 50°C for 3 hours, calcined at 450°C for 3 hours, and ground to a fineness of 120 mesh or higher to obtain substance C.

[0070] S24. Add the substance C obtained in step S23 to a mixed solution of ammonium molybdate, ammonium metatungstate, and praseodymium nitrate, transfer it to a polytetrafluoroethylene reactor, react at 60°C for 12 hours, dry at 80°C for 3 hours, calcine at 300°C for 5 hours, and grind it to a fineness of 120 mesh or higher to obtain substance D.

[0071] S25. The substance D obtained in step S24 is treated at 350°C and under a 15% H2-Ar atmosphere for 1 hour, and then oxidized at 450°C for 2 hours to obtain an arsenic-resistant and alkali-resistant multi-component mesoporous composite oxide denitration catalyst.

[0072] Example 3

[0073] This embodiment provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst, wherein:

[0074] The mass ratio of active component to carrier is 15:100;

[0075] The mass ratio of the catalyst to the support is 8:100;

[0076] In the carrier, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide is 100:30:30;

[0077] The calcium content in calcium-based bentonite is 5%;

[0078] In the active components, the mass ratio of oxides of vanadium, chromium, samarium, and niobium is 10:5:2:2;

[0079] In the co-catalyst, the mass ratio of molybdenum oxide to praseodymium oxide is 1:2.

[0080] This embodiment also provides a method for preparing an arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0081] S31. Mix calcium-based bentonite and attapulgite evenly, and calcine at 650℃ for 10 hours to obtain substance A.

[0082] S32. Mix the substance A obtained in step S31 with nano-cerium oxide evenly, impregnate it in a solution of hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride modifier, react at 80°C for 8 hours, wash with deionized water until pH is 8, dry at 80°C for 15 hours, and calcine at 450°C for 6 hours to obtain substance B.

[0083] The mass ratio of the carrier (substance A and nano-cerium oxide), hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride is 100:2:0.5:0.3.

[0084] S33. The substance B obtained in step S32 is immersed in a mixed solution of ammonium metavanadate, chromium nitrate, samarium nitrate and niobium chloride, transferred to a polytetrafluoroethylene reactor and reacted at 180°C for 6 hours. After drying at 80°C for 5 hours, calcining at 650°C for 3 hours, and grinding to a fineness of 120 mesh or higher, substance C is obtained.

[0085] S34. Add the substance C obtained in step S33 to a mixed solution of ammonium molybdate, ammonium metatungstate, and praseodymium sulfate, transfer it to a polytetrafluoroethylene reactor, react at 100°C for 36 hours, dry at 120°C for 5 hours, calcine at 300°C for 5 hours, and grind it to a fineness of 120 mesh or higher to obtain substance D.

[0086] S35. The substance D obtained in step S34 is treated at 350℃ and 5% H2-Ar atmosphere for 5h, and then oxidized at 650℃ for 8h to obtain an arsenic-resistant and alkali-resistant multi-component mesoporous composite oxide denitrification catalyst.

[0087] Example 4

[0088] This embodiment provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst, wherein:

[0089] The mass ratio of active component to carrier is 10:100;

[0090] The mass ratio of the catalyst to the support is 7:100;

[0091] In the carrier, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide is 100:10:30;

[0092] The calcium content in calcium-based bentonite is 5%;

[0093] In the active components, the mass ratio of oxides of vanadium, chromium, samarium, and niobium is 10:5:2:0.2;

[0094] In the co-catalyst, the mass ratio of molybdenum oxide to praseodymium oxide is 1:0.5.

[0095] This embodiment also provides a method for preparing an arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0096] S41. Mix calcium-based bentonite and attapulgite evenly, and calcine at 580℃ for 6 hours to obtain substance A.

[0097] S42. Mix the substance A obtained in step S41 with nano-cerium oxide evenly, impregnate it in a solution of hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride modifier, react at 66°C for 8 hours, wash with deionized water until pH is 6, dry at 55°C for 9 hours, and calcine at 400°C for 4 hours to obtain substance B;

[0098] The mass ratio of the carrier (substance A and nano-cerium oxide), hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride is 100:1:0.15:0.2.

[0099] S43. The substance B obtained in step S42 is immersed in a mixed solution of vanadium oxysulfate, chromium chloride, samarium sulfate and niobium chloride, transferred to a polytetrafluoroethylene reactor and reacted at 110°C for 5 hours. After drying at 62°C for 3.5 hours, calcining at 500°C for 3.5 hours, and grinding to a fineness of 120 mesh or higher, substance C is obtained.

[0100] S44. Add the substance C obtained in step S43 to a mixed solution of ammonium molybdate, ammonium paratungstate, and praseodymium sulfate, transfer it to a polytetrafluoroethylene reactor, react at 80°C for 2.5 hours, dry at 90°C for 4 hours, calcine at 320°C for 6 hours, and grind it to a fineness of 120 mesh or higher to obtain substance D.

[0101] S45. The substance D obtained in step S44 is treated at 510℃ in a 6% H2-Ar mixed atmosphere for 4.5h, and then oxidized at 560℃ for 5h to obtain an arsenic-resistant and alkali-resistant multi-component mesoporous composite oxide denitration catalyst.

[0102] Example 5

[0103] This embodiment provides an arsenic- and alkali-poisoning-resistant denitrification catalyst, comprising: a support, an active component, and a co-catalyst, wherein:

[0104] The mass ratio of active component to carrier is 12:100;

[0105] The mass ratio of the catalyst to the support is 100.

[0106] In the carrier, the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide is 100:28:6;

[0107] The calcium content in calcium-based bentonite is 5%;

[0108] In the active components, the mass ratio of oxides of vanadium, chromium, samarium, and niobium is 10:0.6:0.1:1.8.

[0109] In the co-catalyst, the mass ratio of the oxides of molybdenum, tungsten, and praseodymium is 1:0.1:2.

[0110] This embodiment also provides a method for preparing an arsenic-resistant and alkali-resistant denitrification catalyst, comprising the following steps:

[0111] S51. Mix calcium-based bentonite and attapulgite evenly, and calcine at 630℃ for 5 hours to obtain substance A.

[0112] S52. Mix the substance A obtained in step S51 with nano-cerium oxide evenly, impregnate it in a solution of hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride modifier, react at 75°C for 10 h, wash with deionized water until pH is 8, dry at 70°C for 8 h, and calcine at 420°C for 5 h to obtain substance B;

[0113] The mass ratio of the carrier (substance A and nano-cerium oxide), hexadecyl dimethyl benzyl ammonium bromide (chloride), octadecyl trimethyl ammonium bromide (chloride), and titanium chloride is 100:2:0.45:0.06.

[0114] S53. The substance B obtained in step S52 is immersed in a mixed solution of ammonium metavanadate, chromium nitrate, samarium nitrate and niobium chloride, transferred to a polytetrafluoroethylene reactor and reacted at 130°C for 3 hours, dried at 65°C for 3.5 hours, calcined at 610°C for 5 hours, and ground to a fineness of 120 mesh or higher to obtain substance C.

[0115] S54. Add the substance C obtained in step S53 to a mixed solution of ammonium molybdate, ammonium paratungstate, and praseodymium sulfate, transfer it to a polytetrafluoroethylene reactor, react at 65°C for 3.5 hours, dry at 110°C for 5 hours, calcine at 320°C for 7 hours, and grind it to a fineness of 120 mesh or higher to obtain substance D.

[0116] S55. The substance D obtained in step S54 is treated at 530℃ in a 12% H2-Ar mixed atmosphere for 3.5h, and then oxidized at 580℃ for 7h to obtain an arsenic-resistant and alkali-resistant multi-component mesoporous composite oxide denitrification catalyst.

[0117] Compare with Example 1

[0118] The difference between this comparative example and Example 1 is that the carrier is prepared by uniformly mixing calcium-based bentonite, attapulgite, and nano-cerium oxide, while the rest is the same as in Example 1.

[0119] Compare with Example 2

[0120] The difference between this comparative example and Example 1 is that the co-catalyst is removed, while the rest is the same as Example 1.

[0121] Compare with Example 3

[0122] The difference between this comparative example and Example 1 is that the active components are vanadium and chromium oxide, while the rest are the same as in Example 1.

[0123] Compare with Example 4

[0124] The difference between this comparative example and Example 1 is that the co-catalyst and the active component are prepared into a mixed solution, and the reaction, drying and calcination processes are the same as in step S13. The rest are the same as in Example 1.

[0125] Compare with Example 5

[0126] The difference between this comparative example and Example 1 is that the substance D obtained in step 14 is not reduced but directly oxidized; otherwise, it is the same as in Example 1.

[0127] Compare with Example 6

[0128] The difference between this comparative example and Example 1 is that the calcium in the calcium-containing bentonite was completely replaced with cerium, while the rest is the same as in Example 1.

[0129] Test case

[0130] To investigate the activity of the denitrification catalysts prepared in the above examples and control examples, their denitrification efficiency was tested at a flue gas temperature of 280-500℃.

[0131] The test conditions are as follows: test temperature 250-450℃, NH3 volume concentration 500ppm, NH3 / NO = 1, GHSV = 120000h. -1 The test results are shown in Table 1.

[0132] Table 1 Catalyst Denitrification Efficiency

[0133]

[0134] As shown in Table 1, the arsenic poisoning-resistant denitrification catalyst prepared by the method of the present invention has high denitrification efficiency and excellent denitrification performance in the temperature range of 250-500℃.

[0135] To investigate the denitrification activity (loaded with 1% As2O3 and 1% Na2O), catalyst surface area, As2O3 deposition amount, and N2 selectivity of the above-mentioned examples and control examples at 350℃, the test results are shown in Table 2.

[0136] Specifically, the denitrification catalyst is ground, passed through an 80-100 mesh sieve, the catalyst powder is weighed, placed in a three-necked flask, KNO3 solution is added, the mixture is stirred in a water bath at 80°C for 2 hours, then dried, and calcined at 550°C in air atmosphere to obtain the product.

[0137] Specifically, the denitrification catalyst is placed in a fixed-bed reactor. An arsenic-containing solution is injected into a preheater via a peristaltic pump, where it is heated to form gaseous As2O3. An N2 / O2 mixture is used as a carrier gas to carry the gaseous As2O3 into the reactor, where it is deposited on the catalyst. By controlling parameters such as the concentration of the arsenic-containing solution, the peristaltic pump flow rate, and the preheater temperature, the loading of As2O3 on the catalyst is accurately achieved.

[0138] The SO2 / SO3 oxidation rate was tested according to the industry standard DL / T2279-2021 "Test Method for Sulfur Dioxide Oxidation Rate of Flue Gas Denitrification Catalysts in Thermal Power Plants (Powder Method)".

[0139] Table 2 Performance of Denitrification Catalysts

[0140]

[0141]

[0142] In summary, the denitrification catalyst prepared by this invention exhibits good denitrification activity (up to 90.2%) when loaded with 1% As2O3 at a flue gas temperature of 350℃; good denitrification activity (up to 93.1%) when loaded with 1% Na2O; and good denitrification activity (up to 88.3%) when loaded with both 1% As2O3 and 1% Na2O. The N2 selectivity is as high as 99.2%, and the As2O3 deposition on the catalyst surface is only 0.20% after 100 hours, demonstrating good resistance to arsenic and alkali metal poisoning and reducing As2O3 deposition on the catalyst surface.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A denitrification catalyst resistant to arsenic and alkali poisoning, characterized in that, include: Support, active component, and cocatalyst; The mass ratio of the active component to the carrier is (3-15):100; The mass ratio of the co-catalyst to the support is (3-8):100; The carrier comprises: calcium-based bentonite, attapulgite, and nano-cerium oxide; wherein the mass ratio of calcium-based bentonite, attapulgite, and nano-cerium oxide in the carrier is 100:(10~30):(5~30); The active component is an oxide of vanadium, chromium, samarium, and niobium; the mass ratio of the oxides of vanadium, chromium, samarium, and niobium in the active component is 10: (0.5~5): (0.1~2): (0.1~2). The co-catalyst is an oxide of molybdenum and praseodymium, or the co-catalyst is an oxide of molybdenum, tungsten, and praseodymium; the mass ratio of the oxides of molybdenum, tungsten, and praseodymium in the co-catalyst is 1:(0~1):(0.5~3). The preparation method of the aforementioned arsenic-resistant and alkali-resistant denitrification catalyst includes the following steps: S1. Mix calcium-based bentonite and attapulgite evenly and calcine to obtain substance A; S2. Mix the substance A obtained in step S1 with nano-cerium oxide evenly, impregnate it in a modifier solution, and calcine to obtain substance B; the modifier includes: modifier E, modifier F and modifier G: modifier E is any one of hexadecyl dimethyl benzyl ammonium bromide and hexadecyl dimethyl benzyl ammonium chloride; modifier F is any one of octadecyl trimethyl ammonium bromide and octadecyl trimethyl ammonium chloride; modifier G is titanium chloride; the mass ratio of substance A to nano-cerium oxide, modifier E, modifier F and modifier G is 100:(1~2):(0.1~0.5):(0.05~0.3); S3. Immerse the substance B obtained in step S2 into the mixed solution of active component precursors, transfer it into a polytetrafluoroethylene reactor and react at 100~180℃ for 2~6h, dry at 50~80℃ for 3~5h, calcine at 450~650℃ for 3~6h, and grind it to 120 mesh or higher to obtain substance C. S4. Add the substance C obtained in step S3 to the mixed solution of the catalyst precursor, transfer it to a polytetrafluoroethylene reactor and react at 60~100℃ for 12~36h, dry at 80~120℃ for 3~5h, calcine at 300~400℃ for 5~8h, and grind it to 120 mesh or higher to obtain substance D. S5. The substance D obtained in step S4 is treated under a reducing atmosphere and then under an oxidizing atmosphere to obtain an arsenic-resistant and alkali-resistant denitrification catalyst.

2. The anti-arsenical anti-alkaline poisoning de-NOx catalyst according to claim 1, characterized by, In step S3, The active component precursors include precursors of vanadium, chromium, samarium, and niobium; The precursor of vanadium is either ammonium metavanadate or vanadium oxysulfate. The precursor of chromium is any one of chromium nitrate, chromium chloride, and chromium sulfate; The precursor of samarium is any one of samarium nitrate, samarium sulfate, and samarium chloride; The precursor of niobium is niobium chloride.

3. The anti-arsenical anti-alkaline poisoning de-NOx catalyst according to claim 1, characterized by, In step S4, The cocatalyst precursor includes one or more of the following: molybdenum, tungsten, and praseodymium precursors; The precursor of molybdenum is ammonium molybdate; The precursor of tungsten is either ammonium metatungstate or ammonium paratungstate. The precursor of praseodymium is any one of praseodymium nitrate, praseodymium sulfate, and praseodymium chloride.

4. The arsenic-resistant and alkali-resistant denitrification catalyst according to claim 1, characterized in that, In step S5, The reducing atmosphere is H2-Ar mixed gas, and the oxidizing atmosphere is air.

Images