CN107096524B - Preparation method of honeycomb denitration catalyst with improved specific surface area - Google Patents
Preparation method of honeycomb denitration catalyst with improved specific surface area Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 159
- 238000002360 preparation method Methods 0.000 title claims abstract description 35
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 111
- 238000002156 mixing Methods 0.000 claims abstract description 66
- 239000002243 precursor Substances 0.000 claims abstract description 62
- 239000002002 slurry Substances 0.000 claims abstract description 48
- 238000003756 stirring Methods 0.000 claims abstract description 48
- 239000000843 powder Substances 0.000 claims abstract description 43
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 38
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims abstract description 38
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000010936 titanium Substances 0.000 claims abstract description 34
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 34
- 238000001035 drying Methods 0.000 claims abstract description 31
- 239000000463 material Substances 0.000 claims abstract description 27
- 229910001930 tungsten oxide Inorganic materials 0.000 claims abstract description 21
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001914 filtration Methods 0.000 claims abstract description 17
- 238000005406 washing Methods 0.000 claims abstract description 17
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 16
- 239000010937 tungsten Substances 0.000 claims abstract description 16
- 230000001376 precipitating effect Effects 0.000 claims abstract description 15
- 238000004537 pulping Methods 0.000 claims abstract description 15
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 14
- 239000011248 coating agent Substances 0.000 claims abstract description 14
- 238000000576 coating method Methods 0.000 claims abstract description 14
- 239000011261 inert gas Substances 0.000 claims abstract description 9
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 8
- 239000011733 molybdenum Substances 0.000 claims abstract description 8
- 239000012065 filter cake Substances 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 44
- 238000000034 method Methods 0.000 claims description 34
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 29
- 150000001720 carbohydrates Chemical class 0.000 claims description 24
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 claims description 18
- 238000007789 sealing Methods 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 15
- 239000008367 deionised water Substances 0.000 claims description 14
- 229910021641 deionized water Inorganic materials 0.000 claims description 14
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 13
- 239000008103 glucose Substances 0.000 claims description 13
- 230000010355 oscillation Effects 0.000 claims description 10
- 239000011148 porous material Substances 0.000 claims description 4
- 239000002023 wood Substances 0.000 claims description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 2
- 229930006000 Sucrose Natural products 0.000 claims description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 2
- 239000004202 carbamide Substances 0.000 claims description 2
- 150000002016 disaccharides Chemical class 0.000 claims description 2
- 150000004676 glycans Chemical class 0.000 claims description 2
- 238000010907 mechanical stirring Methods 0.000 claims description 2
- 150000002772 monosaccharides Chemical class 0.000 claims description 2
- -1 polyoxyethylene Polymers 0.000 claims description 2
- 229920001282 polysaccharide Polymers 0.000 claims description 2
- 239000005017 polysaccharide Substances 0.000 claims description 2
- 239000005720 sucrose Substances 0.000 claims description 2
- 244000275012 Sesbania cannabina Species 0.000 claims 1
- 125000004432 carbon atom Chemical group C* 0.000 claims 1
- 239000013065 commercial product Substances 0.000 claims 1
- 239000010903 husk Substances 0.000 claims 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 abstract description 11
- 239000003546 flue gas Substances 0.000 abstract description 11
- 230000008021 deposition Effects 0.000 abstract description 8
- 229910001385 heavy metal Inorganic materials 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 54
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid group Chemical group S(O)(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 30
- 229910052757 nitrogen Inorganic materials 0.000 description 27
- 238000004523 catalytic cracking Methods 0.000 description 23
- 239000002699 waste material Substances 0.000 description 20
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 description 17
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 15
- 239000011609 ammonium molybdate Substances 0.000 description 15
- 229940010552 ammonium molybdate Drugs 0.000 description 15
- 235000018660 ammonium molybdate Nutrition 0.000 description 15
- 229910000349 titanium oxysulfate Inorganic materials 0.000 description 15
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 14
- 235000011114 ammonium hydroxide Nutrition 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 14
- XAYGUHUYDMLJJV-UHFFFAOYSA-Z decaazanium;dioxido(dioxo)tungsten;hydron;trioxotungsten Chemical compound [H+].[H+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O XAYGUHUYDMLJJV-UHFFFAOYSA-Z 0.000 description 14
- 235000013162 Cocos nucifera Nutrition 0.000 description 13
- 244000060011 Cocos nucifera Species 0.000 description 13
- 241000219782 Sesbania Species 0.000 description 13
- JKQOBWVOAYFWKG-UHFFFAOYSA-N molybdenum trioxide Inorganic materials O=[Mo](=O)=O JKQOBWVOAYFWKG-UHFFFAOYSA-N 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 9
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical group [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 8
- MAKDTFFYCIMFQP-UHFFFAOYSA-N titanium tungsten Chemical compound [Ti].[W] MAKDTFFYCIMFQP-UHFFFAOYSA-N 0.000 description 8
- 229910001935 vanadium oxide Inorganic materials 0.000 description 8
- 239000013078 crystal Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000000975 co-precipitation Methods 0.000 description 5
- WKXHZKXPFJNBIY-UHFFFAOYSA-N titanium tungsten vanadium Chemical compound [Ti][W][V] WKXHZKXPFJNBIY-UHFFFAOYSA-N 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910000476 molybdenum oxide Inorganic materials 0.000 description 4
- PQQKPALAQIIWST-UHFFFAOYSA-N oxomolybdenum Chemical compound [Mo]=O PQQKPALAQIIWST-UHFFFAOYSA-N 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 239000013543 active substance Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229910003455 mixed metal oxide Inorganic materials 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- ZNOKGRXACCSDPY-UHFFFAOYSA-N tungsten(VI) oxide Inorganic materials O=[W](=O)=O ZNOKGRXACCSDPY-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000012854 evaluation process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- ZFUASHFORHAKBU-UHFFFAOYSA-N oxygen(2-) titanium(4+) trioxotungsten Chemical compound [W](=O)(=O)=O.[O-2].[O-2].[Ti+4] ZFUASHFORHAKBU-UHFFFAOYSA-N 0.000 description 1
- 238000005504 petroleum refining Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/24—Chromium, molybdenum or tungsten
- B01J23/30—Tungsten
-
- B01J35/615—
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/04—Mixing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
Abstract
The invention discloses a preparation method of a honeycomb denitration catalyst with improved specific surface area, which comprises the following steps: (1) mixing activated carbon and sugar solution, and pulping; (2) dissolving a titanium source precursor; (3) dissolving a tungsten source precursor, and mixing the tungsten source precursor with the materials in the steps (1) and (2); (4) adjusting the pH value of the mixed material obtained in the step (3) to 8-13, precipitating, filtering and washing to obtain a filter cake; (5) the filter cake in the step (4) is mixed into slurry, added with a vanadium source precursor solution, mixed and dried, and roasted under the protection of inert gas to form powder; (6) and (3) mixing the solution formed by the molybdenum source precursor and the powder in the step (5) into slurry, stirring, adding a pore-forming agent, stirring for the second time, standing, extruding into a honeycomb shape, drying, coating the surface with nano-tungsten oxide, and roasting in an inert gas environment to obtain the catalyst. The catalyst of the invention can improve the specific surface area of the catalyst and resist the uneven deposition of heavy metals in flue gas on the surface of the catalyst.
Description
Technical Field
The invention relates to a preparation method of a honeycomb denitration catalyst with an improved specific surface area, in particular to a preparation method of a denitration catalyst capable of resisting uneven vanadium deposition in flue gas, and belongs to the technical field of novel inorganic materials.
Background
Nitrogen Oxides (NO)x) Is one of the main atmospheric pollutants, and the emission requirements are increasingly strict. The stipulation in the 'twelve five' comprehensive working scheme for energy conservation and emission reduction in China is as follows: by 2015, the total national nitrogen oxide emissions were reduced by 10% compared to 2010. GB13223-2001 'atmospheric pollutant emission standard of thermal power plant' issued by the national environmental protection department in 9 months 2011 makes more strict requirements on NOx emission concentration of the thermal power plant: the newly built, expanded and reconstructed coal-fired boiler is specified in the third period of time, and the maximum allowable NOx emission concentration is 100mg/m3. The requirements of the emission standard of pollutants for petroleum refining industry issued by the national environmental protection department are as follows: beginning at 7 months and 1 day in 2015, the requirement of nitrogen oxide in regenerated flue gas discharged by newly-built catalytic cracking device is less than 200mg/m3Particular emission limits of less than 100mg/m3Existing enterprises of 7/1/2017 also implement the standard. Among the various flue gas denitration technologies, Selective Catalytic Reduction (SCR) is still the mainstream technology in the world, and NO thereofxThe removal rate can reach 80-90%. Among them, the denitration catalyst is the core of the SCR technology, developed countries developed a series of denitration catalysts aiming at the characteristics of coal quality, boiler type and the like in the last 80 th century, and many scientific research units and enterprises in China also carried out a series of researches aiming at the conditions of coal-fired boilers and catalytic cracking flue gas in China and developed some denitration catalysts.
CN201010537130 proposes a method for preparing a denitration catalyst by using a hydrothermal method, which comprises mixing a titanium source precursor and a tungsten source precursor, placing the mixture in an autoclave for hydrothermal reaction, filtering, washing and drying to obtain a titanium-tungsten powder denitration catalyst, and introducing vanadium, molybdenum and other elements to prepare a multi-metal oxide catalyst. The active component of the catalyst prepared by the method has small crystal grains and larger specific surface area, but the phenomenon of higher aggregation degree of the same materials can be caused because the active component is not fully mixed, and the activity of the catalyst can be influenced to a certain extent.
CN201110345605 provides a preparation method of a denitration catalyst, which comprises sequentially adding ammonium tungstate, ammonium molybdate and ammonium metavanadate into metatitanic acid slurry, performing ultrasonic pulping, adjusting the pH value to 4.0-6.5, standing, separating and drying to obtain catalyst powder. The method has simple process and low cost, but ammonium metavanadate is added as a solid, the solubility of vanadium is to be verified, and SO is high in activity although the vanadium is not uniformly dispersed2/SO3The conversion rate is higher, and the use performance of the catalyst is influenced.
CN201210400949 proposes a preparation method of titanium dioxide-tungsten trioxide composite powder, which is to add ammonium paratungstate solution into metatitanic acid slurry, stir and directly vacuum-dry to obtain a finished product. The method has simple process, but the titanium-tungsten mixing strength is lower, and the performance of the material is influenced to a certain extent.
In summary, the preparation of the denitration catalyst involves the mixing of various metal oxides, and the difference of the mixing mode and the process cannot completely distinguish the denitration performance of the catalyst, NOxThe conversion rate can reach more than 90 percent, which shows that the catalytic activity of the specific metal oxide is higher, and higher NO can still be obtained due to uneven dispersionxAnd (4) conversion rate. The quality of the overall performance of the catalyst needs to be verified from other aspects of characterization, and the preparation of the catalyst also needs to be compatible with the operability of industrial scale-up.
Disclosure of Invention
The invention mainly aims to provide a preparation method of a honeycomb denitration catalyst with improved specific surface area, which overcomes the defect of unbalanced active centers of the denitration catalyst in high-temperature flue gas in the prior art, can resist the uneven deposition of vanadium oxide on the surface of the denitration catalyst in the flue gas, increases the specific surface area of the denitration catalyst and improves the performance of the denitration catalyst.
The invention aims to realize the purpose, and the preparation method of the honeycomb denitration catalyst with the improved specific surface area comprises the following steps:
(1) mixing activated carbon with the saccharide solution, and pulping;
(2) dissolving a titanium source precursor to form a solution;
(3) dissolving a tungsten source precursor, and uniformly mixing the tungsten source precursor with the solution obtained in the step (1) and the step (2);
(4) uniformly mixing the solution obtained in the step (3), adjusting the pH value of the solution to 8-13, precipitating, filtering and washing to obtain a filter cake;
(5) adding deionized water into the filter cake obtained in the step (4), adjusting into slurry, adding a vanadium source precursor solution, uniformly mixing, drying, and roasting under the protection of inert gas to form powder;
(6) and (3) mixing the solution formed by the molybdenum source precursor and the powder in the step (5) into slurry, stirring, adding a pore-forming agent, stirring for the second time, sealing, standing, extruding into a honeycomb shape, drying, coating the surface with nano tungsten oxide, and roasting under the protection of inert gas to form the denitration catalyst.
In the invention, the titanium source precursor, the tungsten source precursor, the vanadium source precursor, the molybdenum source precursor and the pore-forming agent are all used substances commonly used in the preparation of the denitration catalyst in the prior art, and the dosage is also selected according to the process characteristics, but the invention is not particularly limited. The invention also recommends a preferred scheme.
The activated carbon in the step (1) of the invention can be common activated carbon, can be wood activated carbon or can be shell activated carbon, the used activated carbon is powdered activated carbon, the granularity is 10-500 meshes, preferably 180-300 meshes, and the specific surface area is preferably 600-2000 m2The pore volume is preferably 0.60 to 1.6 cm/g3/g。
In the method, the activated carbon in the step (1) is firstly treated by sugar and then pulped. The saccharide is one or more of monosaccharide, disaccharide and polysaccharide, preferably saccharide with carbon atom of 3-18, more preferably one or two of sucrose and glucose. The mass of the saccharides is 3 to 40%, preferably 10 to 20% of the mass of the activated carbon. The saccharide treatment can be carried out by dissolving saccharide in water, adding into active carbon, and mixing.
In the method, the active carbon quality and the titanium source precursor (TiO) in the step (1)2In terms of) the mass ratio is preferably 1 to 20: 100.
In the preparation method of the denitration catalyst, the titanium source precursor in the step (2) is preferably titanyl sulfate or metatitanic acid, the titanium source precursor is dissolved, and the solvent is preferably sulfuric acid, water, nitric acid or oxalic acid.
In the preparation method of the denitration catalyst, the tungsten source precursor in the step (3) is preferably ammonium paratungstate or ammonium metatungstate, and the tungsten source precursor is prepared from WO3The precursor of the titanium source is calculated as TiO2Preferably, the mass ratio of the tungsten source precursor to the titanium source precursor used in the step (3) is 2.0-5.0: 100.
The preparation method of the denitration catalyst comprises the steps of (3), (5) and (6) adopting mechanical stirring and mixing, hydrodynamic mixing or \ and ultrasonic oscillation mixing, wherein the mixing time of the steps of (3) and (5) is preferably 0.5-3 h, the mixing time of the step of (6) is preferably 10-60 min, and the sealing and standing time of the step of (6) is preferably 8-30 h.
In the preparation method of the denitration catalyst, the agent used for adjusting the pH value in the step (4) is preferably ammonia water or potassium hydroxide, and the adjusted pH value is preferably 8-13.
In the preparation method of the denitration catalyst, a vanadium source precursor in the vanadium source precursor solution in the step (5) is preferably ammonium metavanadate or ammonium vanadate, and the vanadium source precursor is represented by V2O5The precursor of the titanium source is TiO2The mass ratio of the vanadium source precursor to the titanium source precursor is preferably 1.0-6.0: 100.
The preparation method of the denitration catalyst provided by the invention is characterized in that the roasting temperature in the step (5) and the roasting temperature in the step (6) are both preferably 400-650 ℃, the roasting time is both preferably 4-10 h, and inert gas is required to be added for protection in the roasting process.
In the preparation method of the denitration catalyst, inert gas is required to be added for protection in the roasting process in the step (5) and the step (6), and the inert gas can be nitrogen or helium, preferably nitrogen.
In the preparation method of the denitration catalyst, the molybdenum source precursor in the step (6) is preferably ammonium molybdate, and MoO is used as the molybdenum source precursor3The precursor of the titanium source is calculated as TiO2The mass ratio of the molybdenum source precursor to the titanium source precursor is preferably 0.5-2: 100.
The preparation method of the denitration catalyst comprises the step (6), wherein the pore-forming agent added in the step (6) is preferably one or more of urea, polyoxyethylene and sesbania powder, and the mass ratio of the added pore-forming agent to the titanium source precursor is preferably 0.5-1.5: 100.
The preparation method of the denitration catalyst comprises the step (6) of mixing the nanometer tungsten oxide with WO3The precursor of the titanium source is calculated as TiO2The mass ratio of the tungsten oxide to the titanium source precursor is 1-10: 100, preferably 3-6: 100.
The invention also provides a denitration catalyst, which is prepared by the preparation method of the denitration catalyst.
The invention has the beneficial effects that:
(1) in the preparation process of the catalyst, activated carbon is adopted, particularly after the activated carbon is treated by saccharides and then is pulped, the saccharides are absorbed in the activated carbon, the saccharides in the activated carbon are decomposed and carbonized through subsequent roasting to form new amorphous titanium tungsten, the combination of the new amorphous titanium tungsten is tighter, the saccharides on the inner hole of the activated carbon are decomposed to form a new activated carbon interior surface, and the active sites on the inner surface of the activated carbon are increased. Therefore, the saccharide-treated activated carbon can promote amorphous titanium oxide and tungsten oxide to more tightly wrap the activated carbon, improve the strength of the catalyst and simultaneously improve the specific surface area of the catalyst (the specific surface area is 140 m)2More than/g) and porosity, improving the efficiency of the catalyst.
(2) By utilizing an in-situ mixing method, titanium atoms and tungsten atoms are mixed at an atomic level, so that crystals generated in a subsequent coprecipitation process have more lattice defects, the particle size of mixed metal oxides is small and uniform, the specific surface area is large, the crystal transition temperature of titanium dioxide crystals is increased, and the exertion of catalytic activity is facilitated;
(3) the method of ultrasonic-assisted mixing is adopted, so that the mixing of various materials at the atomic level is more uniform;
(4) the vanadium source is added when the titanium source and tungsten source coprecipitation material is not roasted, the vanadium source penetrates deeper on the surface of the titanium-tungsten particles, the connection is tighter, the dispersion is more uniform, and the activity of the catalyst is more stable after roasting;
(5) after the prepared vanadium-tungsten-titanium powder material is roasted for one time, a layer of molybdenum oxide is covered on the surface of the vanadium-tungsten-titanium powder material, and meanwhile, a pore-forming agent is added, so that the surface of catalyst particles has more molybdenum oxide attachments, and meanwhile, the catalyst particles also have rich space network-shaped nano-scale micropores, thereby not only resisting the uneven deposition of vanadium oxide on the surface of the catalyst particles in flue gas, but also ensuring high catalyst performance;
(6) after the catalyst is formed and dried, a layer of nano-scale tungsten oxide is coated on the surface of the catalyst, so that the performance of the catalyst is improved.
Detailed Description
The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.
Titanium source precursor solution:
in the present invention, the titanium source precursor is dissolved in sulfuric acid to form a solution, and the titanium source precursor is not particularly limited, but is usually limited to titanyl sulfate or metatitanic acid, and the solution of the titanium source precursor is made of TiO2And the content of the titanium source precursor is 15-40 g/L. If the concentration is less than 15g/L, the solution is too dilute, the combination with other materials is loose, and the production efficiency is low; if it exceeds 40g/L, the mixing strength with other materials is lowered due to too high concentration, resulting in poor fusion.
The mixing process of the catalyst sample and the catalytic cracking waste catalyst comprises the following steps: crushing the prepared fresh catalyst, and screening to obtain 20-40 mesh powder; screening catalytic cracking waste catalysts (LDC series) and taking 40-60 mesh powder, wherein the content of vanadium oxide in the catalytic cracking waste catalysts is about 1%. The two powders were mixed at a mass ratio of 1:1, mixed at 350 ℃ for 24 hours in an air atmosphere, and then sieved to obtain catalyst powders for evaluation. In the process of contacting and mixing the fresh catalyst and the waste catalytic cracking catalyst, active substances vanadium in the waste catalytic cracking catalyst are unevenly transferred to the fresh catalyst, SO that the active substances vanadium oxide on the surface of the fresh catalyst are intensively accumulated, the local activity of the catalyst is enhanced, and the SO of the catalyst is increased2/SO3The conversion rate and the overall performance of the denitration catalyst are reduced.
NOxConversion evaluation conditions: space velocity of 20000h-1Reaction temperature of 350 ℃ and inlet gas NOx600mg/Nm3、SO2Is 1000mg/Nm3The ammonia-nitrogen ratio is 1, and the water content is 10%.
NOx、SO2The concentration measuring method comprises the following steps: a continuous on-line flue gas analyzer, siemens ULTRAMAT 23.
SO2/SO3The conversion rate determination method comprises the following steps: limestone-gypsum wet flue gas desulfurization device performance acceptance test specification (DL/T998-2006).
Coconut shell activated carbon: 300 mesh in particle size and 8000m in specific surface area2G, pore volume 1.0cm3/g
Wood activated carbon: particle size 300 mesh, specific surface area 600m2G, pore volume 0.60cm3/g
The following examples are specific illustrations of the present invention, and "%" described in examples and comparative examples means mass percent.
Example 1:
adding 20g of coconut shell activated carbon into glucose solution, fully mixing, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Ammonium paratungstate counted by 10gThe solution is ultrasonically oscillated for 2 hours, ammonia water is gradually added to adjust the pH value to 9.5, and after complete precipitation, filtration and washing are carried out; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 5g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 1.5h, directly drying, and roasting for 6h at the temperature of 620 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by 10g of ammonium molybdate, adding 4g of sesbania powder after stirring, stirring for 40min, sealing and standing for 24h, extruding into a honeycomb shape, drying, coating 15g of nano tungsten oxide, and roasting at 600 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The specific surface area of the catalyst is 144m2(ii) in terms of/g. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 1:
in the catalyst preparation process, no active carbon is added, namely TiO is added2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 10g of ammonium paratungstate solution, oscillating for 2 hours by ultrasonic wave, gradually adding ammonia water to adjust the pH value to 9.5, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 5g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 1.5h, directly drying, and roasting for 6h at the temperature of 620 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by 10g of ammonium molybdate, adding 4g of sesbania powder after stirring, stirring for 40min, sealing and standing for 24h, extruding into a honeycomb shape, drying, coating 15g of nano tungsten oxide, and roasting at 600 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The specific surface area of the catalyst is 121m2(ii) in terms of/g. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 2
Adding 15g of coconut shell activated carbon into glucose solution, fully mixing and pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 20g of ammonium paratungstate solution, mechanically stirring for 2h, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 10g of ammonium metavanadate solution, mechanically stirring for 1.5h, directly drying, and roasting for 6h at 500 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by using 2.5g of ammonium molybdate, adding 3g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 18g of nano tungsten oxide, and roasting at 550 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 2
In the preparation process of the catalyst, the active carbon is not soaked by sugar, namely 15g of coconut shell active carbon is added into water, fully mixed and pulped to form slurry, and the slurry is mixed with TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 20g of ammonium paratungstate solution, mechanically stirring for 2h, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 10g of ammonium metavanadate solution, mechanically stirring for 1.5h, directly drying, and roasting for 6h at 500 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by using 2.5g of ammonium molybdate, adding 3g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 18g of nano tungsten oxide, and roasting at 550 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The specific surface area of the catalyst is 147m2(ii) in terms of/g. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 3
Adding 20g of coconut shell activated carbon into glucose solution, fully mixing, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Measuring 15g of ammonium paratungstate solution, oscillating for 1h by ultrasonic wave, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 20g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 1.5h, directly drying, and roasting for 6h at 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by using 3g of ammonium molybdate, adding 4g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 25g of nano tungsten oxide, and roasting for 8h at 500 ℃ in a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 3
Adding no nano-tungsten oxide into the catalyst preparation process, namely adding 20g of coconut shell activated carbon into glucose solution, fully mixing and pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Metering 40g of ammonium paratungstate solution, oscillating for 1h by ultrasonic wave, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 50 percent by deionized water, and V is added2O5Measuring 20g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 1.5h, directly drying, and roasting for 6h at 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by using 3g of ammonium molybdate, adding 4g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, and roasting for 8h at 500 ℃ in a nitrogen environment to obtain the denitration catalyst. The fresh catalyst obtained by the method and the catalytic cracking catalystThe catalysts after the vanadium spent catalysts are mixed at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 4
Adding 20g of coconut shell activated carbon into glucose solution, fully mixing, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Measuring 12.5g of ammonium paratungstate solution, oscillating for 3 hours by ultrasonic wave, gradually adding ammonia water to adjust the pH value to 10.5, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 35 percent by deionized water, and V is added2O5Measuring 30g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 1.5h, directly drying, and roasting for 6h at 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water by using 3g of ammonium molybdate, adding 4g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 25g of nano tungsten oxide, and roasting for 8h at 500 ℃ in a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 4
Adding vanadium source after first roasting, namely adding 20g of coconut shell activated carbon into glucose solution, fully mixing and pulping to form slurry, and adding titanium dioxide (TiO)2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Measuring 12.5g of ammonium paratungstate solution, oscillating for 3 hours by ultrasonic wave, gradually adding ammonia water to adjust the pH value to 10.5, precipitating completely, filtering, washing, drying, and roasting for 6 hours at 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO33g of ammonium molybdate are prepared as a 30% aqueous slurry and added with V2O5Preparing 30g of ammonium metavanadate solution into slurry with the water content of 30%, stirring, adding 4g of sesbania powder, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 25g of nano tungsten oxide, and roasting at 500 ℃ for 8h in a nitrogen environment to obtain the denitration catalyst.The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 5
Adding 25g of coconut shell activated carbon into glucose solution, fully mixing, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Measuring 25g of ammonium paratungstate solution, mechanically stirring for 3h, gradually adding ammonia water to adjust the pH value to 10.5, completely precipitating, filtering and washing; then the washed materials are made into slurry with the water content of 35 percent by deionized water, and V is added2O5Measuring 30g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 0.5h, directly drying, and roasting for 6h at the temperature of 650 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 30% of water from 2.5g of ammonium molybdate, adding 2.5g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 15g of nano tungsten oxide, and roasting at 650 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 5
The process of preparing the catalyst only adopts one-time roasting, namely adding 25g of coconut shell activated carbon into glucose solution, fully mixing and pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2Adding a solution containing WO at a concentration of 40g/L3Measuring 25g of ammonium paratungstate solution, mechanically stirring for 3h, gradually adding ammonia water to adjust the pH value to 10.5, completely precipitating, filtering and washing; then the washed materials are made into slurry with the water content of 35 percent by deionized water, and V is added2O5Measuring 30g ammonium metavanadate solution, stirring while ultrasonic oscillating for 0.5h, and mixing with MoO3Preparing slurry containing 30% of water from 2.5g of ammonium molybdate, stirring, adding 2.5g of sesbania powder, stirring for 40min, sealing and standing for 10h, extruding into honeycomb shape, drying, coating with 15g of nano-tungsten oxideAnd roasting the mixture for 8 hours at 650 ℃ in a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 6
Adding 5g of coconut shell activated carbon into glucose solution, fully mixing, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 10g of ammonium paratungstate solution, oscillating by ultrasonic waves for 0.5h, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 35 percent by deionized water, and V is added2O5Measuring 5g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 0.5h, directly drying, and roasting for 6h at 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO3Preparing slurry containing 35% of water by 10g of ammonium molybdate, adding 7.5g of sesbania powder after stirring, stirring for 40min, sealing and standing for 10h, extruding into a honeycomb shape, drying, coating 30g of nano tungsten oxide, and roasting at 400 ℃ for 8h by adopting a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Comparative example 6
Adding 5g of coconut shell activated carbon into glucose solution after primary roasting without adding pore-forming agent, fully mixing and pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 10g of ammonium paratungstate solution, mechanically stirring for 0.5h, gradually adding ammonia water to adjust the pH value to 9.0, precipitating completely, filtering and washing; then the washed materials are made into slurry with the water content of 35 percent by deionized water, and V is added2O55g of ammonium metavanadate solution is counted, mechanically stirred for 0.5h, directly dried and roasted for 6h at the temperature of 400 ℃ in a nitrogen environment; mixing the calcined powder with MoO310g of ammonium molybdate is prepared into slurry with 35 percent of water content, and the slurry is stirredAnd standing for 10h in a sealed manner after 40min, extruding into a honeycomb shape, drying, coating 30g of nano tungsten oxide, and roasting for 8h at 400 ℃ in a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
Example 7
Adding 12.5g of coconut shell activated carbon into glucose solution, mixing fully, pulping to form slurry, and adding TiO2A total of 500g of titanyl sulfate was dissolved in the sulfuric acid solution to form a TiO-containing solution2At 35g/L of solution, a solution containing WO was added3Measuring 17.5g of ammonium paratungstate solution, mechanically stirring for 2 hours, gradually adding ammonia water to adjust the pH value to 9.5, completely precipitating, filtering and washing; then the washed materials are made into slurry with the water content of 40 percent by deionized water, and V is added2O5Measuring 15g of ammonium metavanadate solution, stirring and simultaneously carrying out ultrasonic oscillation for 2 hours, directly drying, and roasting for 6 hours at 530 ℃ in a nitrogen environment; mixing the calcined powder with MoO35g of ammonium molybdate is prepared into slurry containing 35% of water, 5g of sesbania powder is added after stirring, stirring is carried out for 40min, sealing and standing are carried out for 20h, the mixture is extruded into a honeycomb shape, then 20g of nano tungsten oxide is coated after drying, and the mixture is roasted for 8h at 520 ℃ in a nitrogen environment to obtain the denitration catalyst. The obtained fresh catalyst and the catalyst after being mixed with the catalytic cracking vanadium-containing waste catalyst at high temperature are respectively evaluated, and the results are shown in the data of table 1.
TABLE 1 comparative table of evaluation data of examples and comparative examples
By way of examples and comparative examples it was found that: the denitration catalyst for resisting uneven vanadium deposition has good effect, the mixing level of active substances reaches the molecular level through in-situ ultrasonic mixing, slightly-dispersed nano particles are obtained through coprecipitation, and then the nano particles are arranged on the particle surfaceIntroducing vanadium oxide into the surface and shallow layer, roasting to obtain catalyst intermediate, then intensively introducing cocatalyst under the action of pore-forming agent, roasting to obtain final catalyst, and in the catalyst evaluation, NOxThe conversion rate of the catalyst can reach more than 99 percent when the ammonia nitrogen ratio is 1, and SO is obtained after the catalyst is mixed with the catalytic cracking vanadium-containing waste catalyst2/SO3The conversion rate is hardly increased, which shows that the surface of the catalyst hardly generates polycrystalline deposition of vanadium oxide, and the catalyst has excellent performance; in the preparation method of the denitration catalyst, if the denitration catalyst is not treated in the step (6), only the vanadium-tungsten-titanium catalyst sample after the first roasting is reserved, and SO is added after the catalytic cracking of the vanadium-containing waste catalyst2/SO3The conversion rate is slightly increased; if no pore-forming agent is added in the step (6), SO is added after the catalytic cracking vanadium-containing waste catalyst is mixed and treated2/SO3The conversion rate is slightly increased; if the catalyst is prepared by one-time roasting in the preparation process, or the vanadium source is added after one-time roasting, NO in the evaluation process of the catalystxWith a slight decrease in the conversion of SO2/SO3The conversion also increased slightly. In summary, when the fresh denitration catalyst and the treated catalyst prepared by the invention are evaluated under the same conditions, SO is2/SO3The conversion rate is lower than that of other comparative samples, and the effect of resisting the uneven deposition of vanadium oxide in smoke is good.
As can be seen from the specific surface area data of the examples and the comparative examples, after the activated carbon is treated by the sugar, the specific surface area of the catalyst is obviously increased, and the catalytic efficiency is further improved.
The invention has the beneficial effects that:
(1) in the preparation process of the catalyst, activated carbon is adopted, particularly after the activated carbon is treated by saccharides and then is pulped, the saccharides are absorbed in the activated carbon, the saccharides in the activated carbon are decomposed and carbonized through subsequent roasting to form new amorphous titanium tungsten, the combination of the new amorphous titanium tungsten is tighter, the saccharides on the inner hole of the activated carbon are decomposed to form a new activated carbon interior surface, and the active sites on the inner surface of the activated carbon are increased. Therefore, the saccharide treated active carbon can promote amorphous titanium oxide and tungsten oxide to wrap the active carbon more tightly, improve the strength of the catalyst, improve the specific surface area and porosity of the catalyst and improve the efficiency of the catalyst.
(2) By utilizing an in-situ mixing method, titanium atoms and tungsten atoms are mixed at an atomic level, so that crystals generated in a subsequent coprecipitation process have more lattice defects, the particle size of mixed metal oxides is small and uniform, the specific surface area is large, the crystal transition temperature of titanium dioxide crystals is increased, and the exertion of catalytic activity is facilitated;
(3) the method of ultrasonic-assisted mixing is adopted, so that the mixing of various materials at the atomic level is more uniform;
(4) the vanadium source is added when the titanium source and tungsten source coprecipitation material is not roasted, the vanadium source penetrates deeper on the surface of the titanium-tungsten particles, the connection is tighter, the dispersion is more uniform, and the activity of the catalyst is more stable after roasting;
(5) after the prepared vanadium-tungsten-titanium powder material is roasted for one time, a layer of molybdenum oxide is covered on the surface of the vanadium-tungsten-titanium powder material, and meanwhile, a pore-forming agent is added, so that the surface of catalyst particles has more molybdenum oxide adhesion, and meanwhile, the catalyst particles also have rich space network-shaped nano-scale micropores and higher crushing strength, not only can be used for resisting the uneven deposition of vanadium oxide in flue gas on the surface of the catalyst particles, but also can be used for ensuring high catalyst performance.
The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (14)
1. A preparation method of a honeycomb denitration catalyst with improved specific surface area is characterized by comprising the following steps:
(1) mixing activated carbon with the saccharide solution, and pulping;
(2) dissolving a titanium source precursor to form a solution;
(3) dissolving a tungsten source precursor, and uniformly mixing the tungsten source precursor with the materials in the steps (1) and (2);
(4) uniformly mixing the solution obtained in the step (3), adjusting the pH value of the solution to 8-13, precipitating, filtering and washing to obtain a filter cake;
(5) adding deionized water into the filter cake obtained in the step (4), adjusting into slurry, adding a vanadium source precursor solution, uniformly mixing, drying, and roasting under the protection of inert gas to form powder;
(6) and (3) mixing the solution formed by the molybdenum source precursor and the powder in the step (5) into slurry, stirring, adding a pore-forming agent, stirring for the second time, sealing, standing, extruding into a honeycomb shape, drying, coating with nano-tungsten oxide, and roasting under the protection of inert gas to form the denitration catalyst.
2. The preparation method according to claim 1, wherein the activated carbon in the step (1) is a common activated carbon commercial product, the activated carbon is powdered activated carbon, the particle size is 10-500 meshes, and the specific surface area is 600-2000 m2A pore volume of 0.60-1.6 cm3/g。
3. The method according to claim 1, wherein the saccharide in step (1) is one or more of a monosaccharide, a disaccharide and a polysaccharide; the mass of the saccharides accounts for 3-40% of the mass of the activated carbon; the saccharide is prepared by dissolving saccharide in water, adding activated carbon, and mixing.
4. The method according to claim 1, wherein the precursor of the titanium source is TiO2And (2) measuring the mass ratio of the activated carbon in the step (1) to the titanium source precursor to be 1-20: 100.
5. The method according to claim 1, wherein in the step (3), the tungsten source precursor is selected from the group consisting of WO3The precursor of the titanium source is calculated as TiO2The mass ratio of the tungsten source precursor to the titanium source precursor is 2.0-5.0: 100.
6. The preparation method according to claim 1, wherein the mixing modes in the step (3), the step (5) and the step (6) are mechanical stirring mixing, hydrodynamic mixing or \ and ultrasonic oscillation mixing, the mixing time of the step (3) and the step (5) is 0.5-3 h, the mixing time of the step (6) is 10-60 min, and the sealing standing time of the step (6) is 8-30 h.
7. The method according to claim 1, wherein the vanadium source precursor in the step (5) is represented by V2O5The precursor of the titanium source is TiO2And the mass ratio of the vanadium source precursor to the titanium source precursor is 1-6: 100.
8. The method according to claim 1, wherein the precursor of the titanium source in the step (6) is TiO2And the mass ratio of the addition amount of the nano-scale tungsten oxide to the titanium source precursor is 3-6: 100.
9. The preparation method according to claim 1, wherein the roasting temperature in the step (5) and the roasting time in the step (6) are both 400-650 ℃ and 4-10 h.
10. The preparation method according to claim 1, wherein the pore-forming agent added in the step (6) is one or more of urea, polyoxyethylene and sesbania powder, and the titanium source precursor is TiO2The mass ratio of the added pore-forming agent to the titanium source precursor is 0.5-1.5: 100.
11. The method according to claim 2, wherein the common activated carbon is wood activated carbon or husk activated carbon having a particle size of 180 to 300 mesh.
12. The method according to claim 3, wherein the saccharide has 3 to 18 carbon atoms.
13. The method according to claim 3, wherein the saccharide is one or both of sucrose and glucose.
14. The method according to claim 3, wherein the mass of the saccharide is 10 to 20% of the mass of the activated carbon.
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| CN101232936A (en) * | 2005-07-12 | 2008-07-30 | 丰田自动车株式会社 | Exhaust gas purifying catalyst and process for producing it |
| CN103386304A (en) * | 2013-08-04 | 2013-11-13 | 江苏安琪尔废气净化有限公司 | Preparation method of catalyst for catalytic combustion of volatile organic compounds |
| CN104415781A (en) * | 2013-08-22 | 2015-03-18 | 上海郎特汽车净化器有限公司 | Ship diesel engine gas exhaust denitration catalyst preparation method |
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| CN105837253A (en) * | 2015-02-04 | 2016-08-10 | 杜拉维特股份公司 | Ceramic article and method for production the same |
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| CN101232936A (en) * | 2005-07-12 | 2008-07-30 | 丰田自动车株式会社 | Exhaust gas purifying catalyst and process for producing it |
| CN103386304A (en) * | 2013-08-04 | 2013-11-13 | 江苏安琪尔废气净化有限公司 | Preparation method of catalyst for catalytic combustion of volatile organic compounds |
| CN104415781A (en) * | 2013-08-22 | 2015-03-18 | 上海郎特汽车净化器有限公司 | Ship diesel engine gas exhaust denitration catalyst preparation method |
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| CN105837253A (en) * | 2015-02-04 | 2016-08-10 | 杜拉维特股份公司 | Ceramic article and method for production the same |
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