CN117919931A - Purifying nitrogen-containing volatile organic compounds and NO in waste gasxIs a method and a purification system of (a) - Google Patents
Purifying nitrogen-containing volatile organic compounds and NO in waste gasxIs a method and a purification system of (a) Download PDFInfo
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- CN117919931A CN117919931A CN202211316698.9A CN202211316698A CN117919931A CN 117919931 A CN117919931 A CN 117919931A CN 202211316698 A CN202211316698 A CN 202211316698A CN 117919931 A CN117919931 A CN 117919931A
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- 238000000034 method Methods 0.000 title claims abstract description 37
- 239000012855 volatile organic compound Substances 0.000 title claims abstract description 36
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 title claims abstract description 34
- 238000000746 purification Methods 0.000 title claims abstract description 26
- 239000002699 waste material Substances 0.000 title 1
- 239000007789 gas Substances 0.000 claims abstract description 98
- 239000003054 catalyst Substances 0.000 claims abstract description 95
- 230000003647 oxidation Effects 0.000 claims abstract description 87
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 87
- 239000002912 waste gas Substances 0.000 claims abstract description 40
- 238000006243 chemical reaction Methods 0.000 claims abstract description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000001301 oxygen Substances 0.000 claims abstract description 15
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 6
- 229910044991 metal oxide Inorganic materials 0.000 claims description 51
- 150000004706 metal oxides Chemical class 0.000 claims description 51
- 239000002808 molecular sieve Substances 0.000 claims description 49
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims description 49
- 229910052751 metal Inorganic materials 0.000 claims description 48
- 239000002184 metal Substances 0.000 claims description 46
- 238000001035 drying Methods 0.000 claims description 28
- 239000000843 powder Substances 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 14
- 239000002253 acid Substances 0.000 claims description 14
- 239000002243 precursor Substances 0.000 claims description 14
- 229910021645 metal ion Inorganic materials 0.000 claims description 13
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 239000011230 binding agent Substances 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
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- -1 amine compounds Chemical class 0.000 claims description 8
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- 229920000609 methyl cellulose Polymers 0.000 claims description 7
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- 235000010981 methylcellulose Nutrition 0.000 claims description 7
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 6
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- 239000002841 Lewis acid Substances 0.000 claims description 5
- 238000000975 co-precipitation Methods 0.000 claims description 5
- 150000007517 lewis acids Chemical class 0.000 claims description 5
- 229910000510 noble metal Inorganic materials 0.000 claims description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 4
- 238000001354 calcination Methods 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- 150000002602 lanthanoids Chemical class 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 4
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 3
- 239000004202 carbamide Substances 0.000 claims description 3
- 239000004927 clay Substances 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 3
- LNAZSHAWQACDHT-XIYTZBAFSA-N (2r,3r,4s,5r,6s)-4,5-dimethoxy-2-(methoxymethyl)-3-[(2s,3r,4s,5r,6r)-3,4,5-trimethoxy-6-(methoxymethyl)oxan-2-yl]oxy-6-[(2r,3r,4s,5r,6r)-4,5,6-trimethoxy-2-(methoxymethyl)oxan-3-yl]oxyoxane Chemical compound CO[C@@H]1[C@@H](OC)[C@H](OC)[C@@H](COC)O[C@H]1O[C@H]1[C@H](OC)[C@@H](OC)[C@H](O[C@H]2[C@@H]([C@@H](OC)[C@H](OC)O[C@@H]2COC)OC)O[C@@H]1COC LNAZSHAWQACDHT-XIYTZBAFSA-N 0.000 claims description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 2
- 230000005587 bubbling Effects 0.000 claims description 2
- 235000013877 carbamide Nutrition 0.000 claims description 2
- 229920002678 cellulose Polymers 0.000 claims description 2
- 239000001913 cellulose Substances 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 2
- 229920003063 hydroxymethyl cellulose Polymers 0.000 claims description 2
- 229940031574 hydroxymethyl cellulose Drugs 0.000 claims description 2
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 2
- 239000012702 metal oxide precursor Substances 0.000 claims description 2
- 150000002825 nitriles Chemical class 0.000 claims description 2
- 235000019353 potassium silicate Nutrition 0.000 claims description 2
- 239000002244 precipitate Substances 0.000 claims description 2
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 2
- 238000012216 screening Methods 0.000 claims description 2
- 238000007873 sieving Methods 0.000 claims description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 claims description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 235000017550 sodium carbonate Nutrition 0.000 claims description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 238000011144 upstream manufacturing Methods 0.000 claims description 2
- 239000003638 chemical reducing agent Substances 0.000 abstract description 8
- 230000003197 catalytic effect Effects 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 25
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 description 12
- 229910010413 TiO 2 Inorganic materials 0.000 description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 7
- 239000003365 glass fiber Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 6
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 6
- 102220042174 rs141655687 Human genes 0.000 description 6
- 239000012046 mixed solvent Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 229910002554 Fe(NO3)3·9H2O Inorganic materials 0.000 description 4
- ZHNUHDYFZUAESO-UHFFFAOYSA-N Formamide Chemical compound NC=O ZHNUHDYFZUAESO-UHFFFAOYSA-N 0.000 description 4
- 238000010531 catalytic reduction reaction Methods 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 229910002492 Ce(NO3)3·6H2O Inorganic materials 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000006555 catalytic reaction Methods 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 238000000769 gas chromatography-flame ionisation detection Methods 0.000 description 3
- 229910001960 metal nitrate Inorganic materials 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000002918 waste heat Substances 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical group C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 229910004664 Cerium(III) chloride Inorganic materials 0.000 description 1
- 229910003297 Ni(NO3)3·6H2O Inorganic materials 0.000 description 1
- 241000219793 Trifolium Species 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- VYLVYHXQOHJDJL-UHFFFAOYSA-K cerium trichloride Chemical compound Cl[Ce](Cl)Cl VYLVYHXQOHJDJL-UHFFFAOYSA-K 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000004630 mental health Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(II) nitrate Inorganic materials [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000012744 reinforcing agent Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
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- 230000001502 supplementing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- ZSDSQXJSNMTJDA-UHFFFAOYSA-N trifluralin Chemical compound CCCN(CCC)C1=C([N+]([O-])=O)C=C(C(F)(F)F)C=C1[N+]([O-])=O ZSDSQXJSNMTJDA-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- 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
- B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/708—Volatile organic compounds V.O.C.'s
Landscapes
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
Abstract
The invention discloses a method and a system for purifying nitrogen-containing volatile organic compounds and NOx in waste gas, which relate to the technical field of waste gas purification and comprise the following steps: (1) Adding free oxygen-containing gas into the waste gas containing nitrogen volatile organic compounds and NO x, and heating the mixed gas to obtain a hot waste gas flow to be treated; (2) And (3) carrying out contact reaction on the hot exhaust gas flow to be treated and an oxidation catalyst, and removing nitrogen-containing volatile organic compounds and NO x in the hot exhaust gas flow to be treated to obtain a purified exhaust gas flow. The invention adopts a catalytic purification method, and can simultaneously remove the nitrogen-containing volatile organic compounds and NO x in the waste gas. By controlling parameters such as reaction temperature, gas flow rate, contact time of gas and oxidation catalyst, the purpose of high-efficiency purification of waste gas is achieved. According to the technical scheme, NO x is reduced without adding a reducing agent, and the NO x can be converted into N 2 by combining an oxidation catalyst with a nitrogenous volatile organic compound in the waste gas as the reducing agent.
Description
Technical Field
The invention relates to the technical field of waste gas purification, in particular to a method and a purification system for purifying nitrogen-containing volatile organic compounds and NO x in waste gas.
Background
Nitrogen-containing volatile organic compounds are a common type of pollutant in industrial exhaust gas, which is commonly found in organic exhaust gas emissions in petrochemical and pharmaceutical industries. The waste gas containing the nitrogen-containing volatile organic compounds is generally or has a malodorous smell or a high toxicity, and can have adverse effects on the environment and the physical and mental health of people. Under certain specific process conditions, nitrogen oxides (NO x) tend to be formed with the production of nitrogen-containing volatile organic compounds. For example, in the production of carbon fibers, the exhaust gas produced contains not only HCN highly toxic substances but also a considerable amount of NO x.
In the prior art, catalytic combustion and selective catalytic reduction are relatively common methods for treating the nitrogen-containing volatile organic compounds and the NO x. The method comprises the steps of deeply oxidizing the nitrogen-containing volatile organic compound into NO x, and then reducing NO x into N 2 by supplementing a reducing agent. For example, patent CN101362051a discloses an acrylonitrile unit tail gas treatment process. And (3) carrying out selective catalytic reduction reaction by taking the added ammonia gas as a reducing agent to reduce nitrogen oxides in the tail gas into nitrogen and water. The disadvantage is that the whole tail gas treatment process requires two reactors and an additional ammonia spraying device, the whole process flow is relatively complex, and secondary pollution caused by ammonia leakage is possibly accompanied. Patent CN 202675299U discloses an incineration treatment device for nitrogen-containing organic matters, which is to treat the nitrogen-containing organic matters by high-temperature incineration and to remove NO x by a serial selective catalytic reduction system. It is also relatively costly and complex in process. Although patent CN 109289911a provides a method for treating nitrogen-containing organic contaminants, it still requires additional NH 3 to be thoroughly purified in the face of NO x.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method and a purifying system for purifying nitrogen-containing volatile organic compounds and NO x in waste gas. According to the invention, nitrogen-containing volatile organic compounds in the waste gas are directly utilized to reduce NO x to N 2, additional NH 3 is not needed to be added as a reducing agent for reducing NO x, and the installation of an ammonia injection grid device and selective catalytic reduction equipment are not needed, so that the problems of cost improvement and secondary pollution caused by the addition of the additional reducing agent in the prior art are avoided; the oxidation catalyst used in the reaction process does not contain any noble metal, and can obtain good simultaneous purification effect under the conditions of low material consumption and low cost.
One of the purposes of the present invention is to provide a method for purifying nitrogen-containing volatile organic compounds and NO x in exhaust gas, comprising the following steps:
(1) Adding free oxygen-containing gas into the waste gas containing nitrogen volatile organic compounds and NO x, and heating the mixed gas to obtain a hot waste gas flow to be treated;
(2) And (3) carrying out contact reaction on the hot exhaust gas flow to be treated and an oxidation catalyst, and removing nitrogen-containing volatile organic compounds and NO x in the hot exhaust gas flow to be treated to obtain a purified exhaust gas flow.
Preferably, in step (1):
The content of the nitrogen-containing volatile organic compounds in the waste gas is 0.01-5%, the content of NO x is not higher than 1%, and the content of oxygen is 1-4% by volume percent; and/or the number of the groups of groups,
The nitrogen-containing volatile organic compound is at least one of fatty amine compounds, amide compounds, aromatic amine compounds, nitrogen-containing heterocyclic compounds and cyanide compounds; and/or the number of the groups of groups,
The NO x is at least one of NO and NO 2、N2 O; and/or the number of the groups of groups,
The molar ratio of the nitrogen-containing volatile organic compounds to the NO x in the hot exhaust stream to be treated is (50-0.1): 1, a step of; and/or the number of the groups of groups,
The oxygen content of the waste gas after the free oxygen-containing gas is supplemented is 6-10%; and/or the number of the groups of groups,
The free oxygen-containing gas comprises air or other oxygen-containing gas based on protective gas, preferably air; and/or the number of the groups of groups,
The temperature of the hot exhaust gas flow to be treated is 200-400 ℃, preferably 250-350 ℃, so that the hot exhaust gas flow to be treated can reach the ignition temperature of the catalytic reaction in the subsequent contact reaction process with the oxidation catalyst, and the catalytic reaction can be performed effectively; and/or the number of the groups of groups,
Removing moisture in the waste gas through gas-liquid separation before the free oxygen-containing gas is supplemented into the waste gas; preferably, the water content in the exhaust gas is reduced to below 1% by volume.
Preferably, in step (2):
The contact reaction of the hot exhaust gas stream to be treated with the oxidation catalyst is carried out in a reactor filled with the oxidation catalyst at a reaction temperature of 300-500 ℃, preferably 350-450 ℃; and/or the contact time is 0.5 to 5s, preferably 0.5 to 1.5s; and/or the linear velocity of the hot exhaust gas stream to be treated is from 0.5 to 2m/s, preferably from 0.5 to 1.5m/s; and/or the number of the groups of groups,
The vent gas stream may be used to heat all or part of the mixed gas described in step (1).
Preferably, the oxidation catalystThe surface density ratio of the acid sites to the Lewis acid sites is 0.25 or more, preferably 0.3 or more; and/or the number of the groups of groups,
The oxidation catalyst comprises a molecular sieve, a metal oxide, a modified metal element and a binder;
the molecular sieve is at least one of MFI type, BEA type, FER type, MOR type and CHA type molecular sieves; the metal element of the metal oxide is at least one element selected from IVB, VB, VIB, VIIB, lanthanoid, rare earth element and does not comprise noble metal.
The modifying metal element is selected from at least one of group VIII, group IB element group, and lanthanide group, and does not include a noble metal.
Preferably, the molecular sieve is present in an amount of from 30 to 80%, preferably from 40 to 70%, by weight based on 100% by weight of the total weight of molecular sieve and metal oxide; the metal oxide content is 20-70%, preferably 30-60%; and/or the number of the groups of groups,
The modified metal element accounts for 0.1-10wt% of the total weight of the molecular sieve and the metal oxide based on the metal element; and/or the number of the groups of groups,
The binder content is 1-20%, preferably 5-15% of the total weight of the molecular sieve and metal oxide.
As a preferred embodiment of the present invention, the molecular sieve is one or both of BEA type molecular sieve and MFI type molecular sieve.
As a preferable aspect of the present invention, the metal element in the metal oxide is at least one selected from Ti, V, mn, fe, co, ni, cu, zr, nb, mo, la, ce, zr, pr, sm, preferably two or more of them; more preferably, the metal element is selected from two or more kinds of Ti, ni, ce, co, fe, la, cu, or three or more kinds; more preferably three or more kinds of Ti, ni, ce, co, fe, la.
As a preferable aspect of the present invention, the metal element of the modified metal is at least one selected from Ce, co, fe, cu, ni, preferably two or more of them; more preferably, the modified metal element may be Fe and/or Cu. The addition of the modified metal plays a role in modifying the molecular sieve, so that the oxidation catalyst has the function of purifying the nitrogen-containing VOCs and NO x in the waste gas simultaneously and efficiently.
The adhesive is at least one of an organic adhesive and an inorganic adhesive; the inorganic binder is preferably one or more of alumina sol, silica sol, natural clay, water glass, silicate and pseudo-boehmite; the organic binder is preferably one or more of polyethylene oxide, polyvinyl alcohol, cellulose, acrylic acid, methyl cellulose and hydroxymethyl cellulose.
Conventional auxiliary agents, such as a structural reinforcing agent capable of improving the strength of the oxidation catalyst, can be added into the formula of the oxidation catalyst according to actual conditions, such as: the glass fiber is used in a conventional amount, and can be added by a technician according to actual conditions.
Preferably, the oxidation catalyst is prepared by the following method:
Preparing the metal oxide by a coprecipitation method, mixing the obtained metal oxide with the molecular sieve and a binder, forming, and roasting to obtain the oxidation catalyst.
Preferably, the preparation of the oxidation catalyst comprises the following specific steps:
(a) The metal oxide is prepared by adopting a coprecipitation method: adding a precipitant into the precursor solution of the metal oxide, drying the obtained precipitate, screening and roasting to obtain the metal oxide;
(b) Mixing metal oxide and/or metal oxide prepared in the step (a) with molecular sieve powder, adding adhesive, adding modified metal precursor solution, kneading, extruding, drying and roasting to obtain the oxidation catalyst.
Preferably, in step (a):
The precipitant is at least one of sodium hydroxide, sodium carbonate, ammonia water, urea and sodium bicarbonate; and/or the number of the groups of groups,
The pH value of the precursor solution of the metal oxide after adding the precipitant is 7-12; and/or the number of the groups of groups,
The precursor of the metal oxide is selected from water-soluble compounds of the metal, preferably at least one of nitrate, sulfate, hydrochloride and oxalate of the metal; and/or the number of the groups of groups,
The precursor of the modified metal element is selected from water-soluble compounds of the modified metal, preferably at least one of nitrate, sulfate, hydrochloride and oxalate of the modified metal; and/or the number of the groups of groups,
The solvent of the precursor solution is at least one of water, ethanol, methanol, glycol and glycerol; and/or the number of the groups of groups,
The molar concentration of the metal ions in the metal oxide precursor solution and the modified metal precursor solution is independently selected from 0.01-10mol/L, preferably 0.1-1mol/L; and/or the number of the groups of groups,
The drying temperature is 60-120 ℃, preferably 80-100 ℃; and/or the number of the groups of groups,
The drying time is 6-48 hours, preferably 12-24 hours; and/or the number of the groups of groups,
The powder particles obtained by sieving are 80-300 meshes, preferably 100-200 meshes; and/or the number of the groups of groups,
The roasting temperature is 300-600 ℃, preferably 400-550 ℃; and/or the number of the groups of groups,
The calcination time is 1 to 12 hours, preferably 4 to 8 hours.
Preferably, in step (b):
The weight ratio of the molecular sieve to the metal oxide is (30-80): (70-20), preferably (40-70): (60-30); and/or the number of the groups of groups,
The binder accounts for 1-20% of the total weight of the molecular sieve and the metal oxide, preferably 5-15%; and/or the number of the groups of groups,
The powder particle diameter D90 of the molecular sieve is smaller than 10 microns; and/or the number of the groups of groups,
The drying temperature is 30-120 ℃, preferably 40-60 ℃; and/or the number of the groups of groups,
The drying time is 6-72 hours, preferably 24-48 hours; and/or the number of the groups of groups,
The roasting temperature is 400-700 ℃, preferably 400-600 ℃; and/or the number of the groups of groups,
The calcination time is 1 to 12 hours, preferably 4 to 8 hours.
The shape of the oxidation catalyst after kneading and extrusion molding is not particularly limited, and may be a molded structure such as a cylinder, clover, raschig, sphere, honeycomb, or the like.
As a preferred mode of the preparation method of the oxidation catalyst of the present invention, when the metal oxide of the oxidation catalyst of the present invention includes TiO 2, the TiO 2 powder may be directly added and mixed in step (b) without co-precipitation in step (a), and TiO 2 simultaneously plays a role of a co-carrier, so that the strength of the oxidation catalyst can be improved.
Another object of the present invention is to provide a purification system for purifying nitrogen-containing volatile organic compounds and NO x in exhaust gas, comprising, in order from the upstream side on an exhaust gas passage: optionally a gas-liquid separation device, a compressor for bubbling a free oxygen-containing gas into the exhaust gas stream to be purified, a heat exchanger for preheating the exhaust gas stream to be purified and a fixed bed reactor, the discharge of which is optionally in communication with the heat exchanger; the oxidation catalyst is filled in the fixed bed reactor.
Preferably, a branch pipeline is arranged on an air inlet pipeline of the heat exchanger and is communicated with an air outlet pipeline of the heat exchanger, and an electric heater is connected in parallel.
By adopting the technical scheme, the method for catalytic purification can simultaneously remove the nitrogen-containing volatile organic compounds and NO x in the waste gas. By controlling parameters such as reaction temperature, gas flow rate, contact time of gas and oxidation catalyst, the purpose of high-efficiency purification of waste gas is achieved. According to the technical scheme, NO x is reduced without adding a reducing agent, and the NO x can be converted into N 2 by combining nitrogen-containing volatile organic compounds in the waste gas as the reducing agent through the design of the oxidation catalyst.
Drawings
FIG. 1 is a schematic diagram of a purification system of the present invention.
The device comprises a waste gas containing 1-nitrogen volatile organic compounds and NO x, a 2-gas-liquid separation device, a 3-compressor, a 4-waste gas flow to be treated, a 5-heat exchanger, a 6-fixed bed reactor, a 7-electric heater, an 8-branch gas flow, a 9-waste gas flow to be purified for removing moisture, a 10-waste heat gas flow, a 11-waste heat gas flow to be treated combined with the branch gas flow, and a 12-exhaust gas flow.
The waste gas 1 containing nitrogen volatile organic compounds and NO x passes through the gas-liquid separation device 2, so that the water content in the gas is reduced, and a waste gas stream 9 to be purified for removing the water is obtained. And then, a proper amount of air is blown into the waste gas flow 9 to be purified, the moisture of which is removed, by utilizing the compressor 3, the waste gas flow 4 to be treated is obtained, and the waste gas flow 4 to be treated is fed into the heat exchanger 5 to be preheated, so that the waste gas flow 10 to be treated is obtained, and the requirement of the ignition temperature of the catalytic reaction is met. The gas stream after catalytic purification by means of a fixed bed reactor 6 containing oxidation catalyst is passed to a heat exchanger 5, the heat of which is used to heat the exhaust gas stream 4 to be treated. The heat exchanged exhaust stream 12 is directly vented to the atmosphere.
In order to be able to optimize the purification conditions further, in which a bypass gas stream 8 of the exhaust gas stream 4 to be treated does not pass through the heat exchanger 5, the flow rate and the temperature of the bypass gas stream 8 are controlled by the electric heater 7, so that the gas stream temperature entering the fixed-bed reactor 6 filled with oxidation catalyst can be controlled effectively to optimize the progress of the reaction. For example, if the temperature of the air flow passing through the heat exchanger 5 cannot reach the required ignition temperature, the bypass air flow 8 can be opened, a part of the exhaust air flow 4 to be treated is quickly heated by the electric heater 7 and is converged into the hot exhaust air flow 10 to be treated to increase the temperature thereof, so as to obtain the hot exhaust air flow 11 to be treated with the bypass air flow combined; if the temperature of the hot exhaust gas stream 11 to be treated, in which the bypass gas stream is incorporated, is too high, the bypass gas stream 8 can likewise be opened, so that a part of the exhaust gas stream 4 to be treated does not pass through the heat exchanger 5 and the electric heater 7 does not heat, thereby reducing the temperature of the hot exhaust gas stream 11 to be treated, in which the bypass gas stream is incorporated, entering the fixed bed reactor 6 and controlling the temperature within a suitable interval.
Detailed Description
The present invention is described in detail below with reference to the specific drawings and examples, and it is necessary to point out that the following examples are given for further illustration of the present invention only and are not to be construed as limiting the scope of the present invention, since numerous insubstantial modifications and adaptations of the invention to those skilled in the art will still fall within the scope of the present invention.
Example 1
Preparation of the oxidation catalyst:
(a) 81.75g Ni(NO3)2·6H2O(0.28mol),12.5g Ce(NO3)3·6H2O(0.028mol) g and 34.5g Co (NO 3)2·6H2 O (0.118 mol) are dissolved in a mixed solvent of 250mL deionized water and 50mL ethanol, and are fully stirred to ensure that metal nitrate is completely dissolved, the sum of the molar concentration of Ni, ce and Co metal ions is about 1.42mol/L, then 2mol/L Na 2CO3 solution is dropwise added to the solution under the heating condition of 45 ℃ until the pH value of a reaction system is=10, and the solution is filtered, washed and dried for 24 hours at the temperature of 60 ℃, and finally the solution is transferred into a muffle furnace to be roasted for 120 minutes at the temperature of 450 ℃ to obtain the metal oxide.
(B) Taking an MFI type molecular sieve: 240g of ZSM-5 molecular sieve powder (molecular sieve particle size D90=9 micron), 80g of TiO 2 powder, and 25g of metal oxide prepared in the step (a) are placed in a stirrer to be fully stirred, then transferred into a kneader, 50g of pseudo-boehmite, 2g of methylcellulose and 10g of glass fiber are added, and all materials are fully stirred for 20min. Adding the prepared solution containing 40g of Fe (NO 3)3·9H2 O and 35g of Cu (150 g of NO 3)2·6H2 O (molar concentration of metal ions is 1.7 mol/L)) into a kneader, fully kneading for 40min to obtain a wet blank, adopting a steel plate with a round hole with the diameter of 4mm as a mould, extruding the wet blank through an extruder to obtain a formed catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 3.24wt% of the total weight of the oxidation catalyst based on the metal element.
For the prepared oxidation catalystThe surface density ratio of the acid sites to the Lewis acid sites was determined. The testing method comprises the following steps: adsorption of infrared light with pyridine first determines the/>, oxidation catalystThe contents of acid and Lewis acid are divided by the specific surface area of the catalyst to obtain the surface density of different acid sites. The density ratio is the division of the two.
The specific surface area of the sample was tested on Micromeritics TriStar 3000,3000 instruments; of samplesThe content of acid and Lewis acid is qualitatively and quantitatively determined by pyridine adsorption infrared. The acid density of the oxidation catalyst sample is calculated as follows:
Wherein n is the content of the acid site measured, mu mol/g; s is the surface area of the sample, m 2/g.
The acid site ratio of the oxidation catalyst prepared in this example was calculated according to the above formula to be 0.45.
Example 2
(A) The procedure for the preparation of the metal oxide is as in example 1.
(B) Taking BEA type molecular sieve: and (3) placing 150g of Beta molecular sieve powder (the particle size D90=9 microns) and 100g of TiO 2 powder in a stirrer, fully stirring 25g of metal oxide prepared in the step (a), then transferring into a kneader, adding 50g of pseudo-boehmite, 2g of methylcellulose and 10g of glass fiber, fully stirring all materials for 20min, adding 40g of prepared solution dissolved with Fe (NO 3)3·9H2 O and 35g of Cu (140 g of solution of NO 3)2·6H2 O (the molar concentration of metal ions is 1.7 mol/L)) into the kneader, fully kneading for 40min to obtain a wet blank, extruding a steel plate with round holes with the diameter of 4mm by adopting a die as a wet blank by adopting the extruder to obtain a molded catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, and then roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal accounts for 3.91wt% of the total weight of the oxidation catalyst in the obtained oxidation catalyst.
The acid site ratio of the oxidation catalyst in this example was measured as in example 1 and found to be 0.38.
Example 3
(A) The procedure for the preparation of the metal oxide is as in example 1.
(B) Taking CHA type molecular sieve: and (3) adding prepared 155g solution (the molar concentration of metal ions is 1.7 mol/L) of solution (NO 3)3·9H2 O and 35g Cu) dissolved with Fe (NO 3)2·6H2 O) into a kneader for fully kneading for 40min to obtain a wet blank, extruding a steel plate with a round hole with the diameter of 4mm through an extruder to obtain a formed catalyst structure, finally, drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 3.52wt% of the total weight of the oxidation catalyst.
The acid site ratio of the oxidation catalyst in this example was measured as in example 1 and found to be 0.35.
Example 4
(A) Taking 81.75gNi (NO 3)2·6H2O,12.5g Ce(NO3)3·6H2 O and 34.5g Co (NO 3)2·6H2 O are dissolved in a mixed solvent of 50mL deionized water and 25mL ethanol), fully stirring to ensure that metal nitrate is completely dissolved, adding 100mL (about 2.13mol/100 mL) of urea aqueous solution containing 5 times of the molar quantity of metal ions to the total molar quantity of metal ions, stirring and refluxing the mixture at 90 ℃ for 6 hours, filtering and washing the obtained product after the reaction is finished, drying the product at 60 ℃ for 24 hours, and finally transferring the product into a muffle furnace for roasting at 450 ℃ for 120 minutes to obtain the metal oxide.
(B) The oxidation catalyst was prepared in the same manner as in example 1, and the modified metal in the obtained oxidation catalyst was 3.24wt% based on the total weight of the oxidation catalyst based on the metal element thereof.
The acid site ratio of the oxidation catalyst in this example was measured as in example 1 and found to be 0.42.
Example 5
(A) Taking 81.75g of Ni (NO 3)2·6H2O,12.5g Ce(NO3)3·6H2 O and 34.5g of Co (NO 3)2·6H2 O are dissolved in a mixed solvent of 50mL of deionized water and 25mL of ethanol) and stirring fully to completely dissolve metal nitrate, then dropwise adding 2mol/L NaOH solution into the solution under the heating condition of 45 ℃ until the pH value of a reaction system is=10, filtering, washing, drying at 60 ℃ for 24 hours, and finally transferring into a muffle furnace to bake for 120 minutes at 450 ℃ to obtain the metal oxide.
(B) Taking an MFI type molecular sieve: 240g of ZSM-5 molecular sieve powder (molecular sieve particle size D90=9 micron), 80g of TiO 2 powder, and 25g of metal oxide prepared in the step (a) are placed in a stirrer to be fully stirred, then transferred into a kneader, 50g of silica sol, 2g of methylcellulose and 10g of glass fiber are added, and all materials are fully stirred for 20min. Adding the prepared 150g solution (the molar concentration of metal ions is 1.7 mol/L) dissolved with 40g Fe (NO 3)3·9H2 O and 35g Cu (NO 3)2·6H2 O) into a kneader, fully kneading for 40min to obtain a wet blank, adopting a steel plate with a round hole with the diameter of 4mm as a mould, extruding the wet blank through the extruder to obtain a formed catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 3.16wt% of the total weight of the oxidation catalyst based on the metal elements.
The acid site ratio of the oxidation catalyst in this example was measured as in example 1 and found to be 0.28.
Example 6
(A) 112.4g Fe 2(SO4)3·9H2O(0.2mol),37.3g CeCl3 (0.1 mol) and 3.25g La (NO 3)3 (0.01 mol) are dissolved in a mixed solvent of 800mL deionized water and 200mL ethanol, and the mixed solvent is fully stirred to enable metal salts to be fully dissolved, the sum of the molar concentration of three metal ions is 0.31mol/L, then 1mol/L NaOH solution is dropwise added to the solution under the condition of heating at 45 ℃ until the pH value of a reaction system is 12, and the solution is dried for 24 hours at 60 ℃ after filtering and washing, and finally the solution is transferred into a muffle furnace to be roasted for 300 minutes at 550 ℃ to obtain metal oxides.
(B) Taking an MFI type molecular sieve: 100g of ZSM-5 molecular sieve powder (molecular sieve particle size D90=9 microns), 150g of TiO 2 powder, and 20g of metal oxide prepared in the step (a) are placed in a stirrer to be fully stirred, then transferred into a kneader, 50g of natural clay, 2g of polyvinyl alcohol and 10g of glass fiber are added, and all materials are fully stirred for 20min. Adding the prepared 150g solution (the molar concentration of metal ions is 1.23 mol/L) dissolved with 30g Fe (NO 3)3·9H2 O and 25g Cu (NO 3)2·6H2 O) into a kneader, fully kneading for 40min to obtain a wet blank, adopting a steel plate with a round hole with the diameter of 4mm as a mould, extruding the wet blank through the extruder to obtain a formed catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 4.09wt% of the total weight of the oxidation catalyst based on the metal elements.
The acid site ratio of the oxidation catalyst in this example was measured as in example 1 and found to be 0.32.
Example 7
(A) The procedure for the preparation of the metal oxide is as in example 1.
(B) Taking an MFI type molecular sieve: 240g of ZSM-5 molecular sieve powder (molecular sieve particle size D90=9 micron), 80g of TiO 2 powder, and 25g of metal oxide prepared in the step (a) are placed in a stirrer to be fully stirred, then transferred into a kneader, 50g of pseudo-boehmite, 2g of methylcellulose and 10g of glass fiber are added, and all materials are fully stirred for 20min. Adding prepared solution containing 10g Ni (NO 3)3·6H2 O and 8g Co (150 g of NO 3)2·6H2 O (molar concentration of metal ions is 0.44 mol/L)) into a kneader, fully kneading for 40min to obtain a wet blank, adopting a steel plate with a round hole with the diameter of 4mm as a mould, extruding the wet blank through an extruder to obtain a formed catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 0.88wt% of the total weight of the oxidation catalyst based on the metal element.
Example 8
(A) The procedure for the preparation of the metal oxide is as in example 1.
(B) Taking an MFI type molecular sieve: 240g of ZSM-5 molecular sieve powder (molecular sieve particle size D90=9 micron), 80g of TiO 2 powder, and 25g of metal oxide prepared in the step (a) are placed in a stirrer to be fully stirred, then transferred into a kneader, 50g of pseudo-boehmite, 2g of methylcellulose and 10g of glass fiber are added, and all materials are fully stirred for 20min. Adding the prepared solution containing 80g of Cu (NO 3)3·6H2 O and 60g of Ce (150 g of NO 3)3·6H2 O (the molar concentration of metal ions is 3.35 mol/L)) into a kneader, fully kneading for 40min to obtain a wet blank, adopting a steel plate with a round hole with the diameter of 4mm as a mould, extruding the wet blank through an extruder to obtain a formed catalyst structure, finally drying at 40 ℃ for 28h, drying at 60 ℃ for 24h, roasting at 550 ℃ for 6h to obtain the final oxidation catalyst, wherein the modified metal in the obtained oxidation catalyst accounts for 9.1wt% of the total weight of the oxidation catalyst based on the metal element.
Example 9
The method for purifying nitrogen-containing volatile organic compounds and NO x in the waste gas comprises the following steps:
The purification system shown in FIG. 1 was employed, in which the pyridine concentration in the exhaust gas stream 4 to be treated obtained after the compressor 3 had been blown with a proper amount of air was 1000ppm, the NO x concentration was 300ppm, the O 2 concentration was 8% by volume, and the H 2 O content was 0.5% by volume. The gas stream was fed into the fixed-bed reactor 6 at a volumetric flow rate of 10Nm 3/h and a linear velocity of 0.6m/s, and the contact reaction time of the hot exhaust gas stream to be treated with the oxidation catalyst was 1s.
The oxidation catalyst used in this example was the oxidation catalyst prepared in example 1, and the loading was 1L and the volume space velocity (based on the total amount of gas passing through the oxidation catalyst) was 10000h -1. The inlet temperature of the exhaust gas stream before entering the fixed bed reactor 6 was 300℃and the concentration of NO x at the outlet after 48 hours of operation was 11.5ppm, the removal efficiency of NO x was 96.2%. The pyridine content is less than 1ppm as measured by GC-IMS, and the purification efficiency is more than 99%.
Example 10
The purification system shown in FIG. 1 was employed, in which, in the exhaust gas stream 4 to be treated obtained after the compressor 3 had been blown with a proper amount of air, the concentration of triethylamine was 500ppm, the concentration of NO x was 300ppm, the concentration of O 2 was 8% by volume and the H 2 O content was 0.5% by volume. The gas stream was fed into the fixed-bed reactor 6 at a volumetric flow rate of 10Nm 3/h and a linear velocity of 0.6m/s, and the contact reaction time of the hot exhaust gas stream to be treated with the oxidation catalyst was 1s.
The oxidation catalyst used in this example was the oxidation catalyst prepared in example 3, and the loading was 1L and the volume space velocity (based on the total amount of gas passing through the oxidation catalyst) was 10000h -1. The inlet temperature of the exhaust gas stream before entering the fixed bed reactor 6 was 320℃and the concentration of NO x at the outlet after 48 hours of operation was 21.3ppm, the removal efficiency of NO x was 92.9%. The triethylamine content is less than 1ppm as measured by GC-FID, and the purification efficiency is more than 99%.
Example 11
The purification system shown in FIG. 1 was employed, in which the concentration of formamide, the concentration of NO x, the concentration of O 2, the volume fraction of 8% and the H 2 O content of 1% were 300ppm, 500ppm, and the volume fraction of the exhaust gas stream 4 to be treated, which was obtained after the compressor 3 had been blown with an appropriate amount of air. The gas stream was fed into the fixed-bed reactor 6 at a volumetric flow rate of 10Nm 3/h and a linear velocity of 0.6m/s, and the contact reaction time of the hot exhaust gas stream to be treated with the oxidation catalyst was 1s.
The oxidation catalyst used in this example was the oxidation catalyst prepared in example 4, and the loading was 1L and the volume space velocity (based on the total amount of gas passing through the oxidation catalyst) was 10000h -1. The inlet temperature of the exhaust gas stream before entering the fixed bed reactor 6 (the temperature of the hot exhaust gas stream to be treated) was 280℃and the concentration of NO x at the outlet after 48 hours of operation was 21.8ppm, the removal efficiency of NO x was 95.7%. The formamide content is 1.8ppm by GC-FID measurement, and the purification efficiency is more than 99%.
Example 12
The purification system shown in FIG. 1 was employed, in which the acetonitrile concentration was 1000ppm, the NO x concentration was 500ppm, the O 2 concentration was 8% by volume and the H 2 O content was 0.5% by volume in the exhaust gas stream 4 to be treated obtained after the compressor 3 had been purged with an appropriate amount of air. The gas stream was fed into the fixed-bed reactor 6 at a volumetric flow rate of 10Nm 3/h and a linear velocity of 0.6m/s, and the contact reaction time of the hot exhaust gas stream to be treated with the oxidation catalyst was 1s.
The oxidation catalyst used in this example was the oxidation catalyst prepared in example 5, and the loading was 1L and the volume space velocity (based on the total amount of gas passing through the oxidation catalyst) was 10000h -1. The inlet temperature of the exhaust gas stream before entering the fixed bed reactor 6 was 320℃and the concentration of NO x at the outlet after 48 hours of operation was 42.7ppm, the removal efficiency of NO x was 91.5%. The acetonitrile content was 2.8ppm as determined by GC-FID, and the purification efficiency was more than 99%.
Example 13
The only difference compared to example 9 is: the concentration of O 2 in the exhaust gas stream 4 to be treated, which is obtained after the compressor 3 has been inflated with a suitable amount of air, is controlled to 6%, the remaining parameters being unchanged.
In this example, the oxidation catalyst of example 1 was used as well, and the reaction parameters were the same as in example 1. The concentration of NO x at the outlet after 48h of operation was 18.7ppm and the removal efficiency of NO x was 93.8%. The pyridine content was 3.6ppm as determined by GC-MS, and the purification efficiency was greater than 99%.
Example 14
The only difference compared to example 9 is: the concentration of O 2 in the exhaust gas stream 4 to be treated, which is obtained after the compressor 3 has been inflated with a suitable amount of air, is controlled to 10%, the remaining parameters being unchanged.
In this example, the oxidation catalyst of example 1 was used as well, and the reaction parameters were the same as in example 1. The concentration of NO x at the outlet after 48h of operation was 21.3ppm and the removal efficiency of NO x was 92.9%. The pyridine content is less than 1ppm as measured by GC-MS, and the purification efficiency is more than 99%.
Claims (12)
1. A method for purifying nitrogen-containing volatile organic compounds and NO x in waste gas comprises the following steps:
(1) Adding free oxygen-containing gas into the waste gas containing nitrogen volatile organic compounds and NO x, and heating the mixed gas to obtain a hot waste gas flow to be treated;
(2) And (3) carrying out contact reaction on the hot exhaust gas flow to be treated and an oxidation catalyst, and removing nitrogen-containing volatile organic compounds and NO x in the hot exhaust gas flow to be treated to obtain a purified exhaust gas flow.
2. The method according to claim 1, characterized in that in step (1):
The content of the nitrogen-containing volatile organic compounds in the waste gas is 0.01-5%, the content of NO x is not higher than 1%, and the content of oxygen is 1-4% by volume percent; and/or the number of the groups of groups,
The nitrogen-containing volatile organic compound is at least one of fatty amine compounds, amide compounds, aromatic amine compounds, nitrogen-containing heterocyclic compounds and cyanide compounds; and/or the number of the groups of groups,
The NO x is at least one of NO and NO 2、N2 O; and/or the number of the groups of groups,
The molar ratio of the nitrogen-containing volatile organic compounds to the NO x in the hot exhaust stream to be treated is (50-0.1): 1, a step of; and/or the number of the groups of groups,
The oxygen content of the waste gas after the free oxygen-containing gas is supplemented is 6-10%; and/or the number of the groups of groups,
The temperature of the hot exhaust gas stream to be treated is 200-400 ℃, preferably 250-350 ℃; and/or the number of the groups of groups,
Removing moisture in the waste gas through gas-liquid separation before the free oxygen-containing gas is supplemented into the waste gas; preferably, the water content in the exhaust gas is reduced to below 1% by volume.
3. The method according to claim 1, characterized in that in step (2):
the reaction temperature of the contact reaction of the hot exhaust gas flow to be treated and the oxidation catalyst is 300-500 ℃, preferably 350-450 ℃; and/or the contact time is 0.5 to 5s, preferably 0.5 to 1.5s; and/or the linear velocity of the hot exhaust gas stream to be treated is from 0.5 to 2m/s, preferably from 0.5 to 1.5m/s; and/or the number of the groups of groups,
The vent gas stream may be used to heat all or part of the mixed gas described in step (1).
4. The method according to claim 1, characterized in that:
the oxidation catalyst The surface density ratio of the acid sites to the Lewis acid sites is 0.25 or more, preferably 0.3 or more; and/or the number of the groups of groups,
The oxidation catalyst comprises a molecular sieve, a metal oxide, a modified metal element and a binder;
The molecular sieve is at least one of MFI type, BEA type, FER type, MOR type and CHA type molecular sieves; the metal element of the metal oxide is at least one element selected from IVB, VB, VIB, VIIB, lanthanoid and rare earth elements, and does not comprise noble metal;
the modifying metal element is selected from at least one of group VIII, group IB element group, and lanthanide group, and does not include a noble metal.
5. The method according to claim 1, characterized in that:
The content of the molecular sieve is 30-80%, preferably 40-70% based on 100% by weight of the total weight of the molecular sieve and the metal oxide; the metal oxide content is 20-70%, preferably 30-60%; and/or the number of the groups of groups,
The modified metal element accounts for 0.1-10wt% of the total weight of the molecular sieve and the metal oxide based on the metal element; and/or the number of the groups of groups,
The binder content is 1-20%, preferably 5-15% of the total weight of the molecular sieve and metal oxide.
6. The method according to claim 1, characterized in that:
The molecular sieve is one or two of BEA type molecular sieve and MFI type molecular sieve; and/or the number of the groups of groups,
The metal element of the metal oxide is selected from at least one of Ti, V, mn, fe, co, ni, cu, zr, nb, mo, la, ce, zr, pr, sm, preferably two or more of them; and/or the number of the groups of groups,
The metal element of the modified metal is selected from at least one, preferably two or more of Ce, co, fe, cu, ni;
The adhesive is at least one of an organic adhesive and an inorganic adhesive; the inorganic binder is preferably one or more of alumina sol, silica sol, natural clay, water glass, silicate and pseudo-boehmite; the organic binder is preferably one or more of polyethylene oxide, polyvinyl alcohol, cellulose, acrylic acid, methyl cellulose and hydroxymethyl cellulose.
7. The process according to any one of claims 4 to 6, characterized in that the oxidation catalyst is prepared by the following method:
Preparing the metal oxide by a coprecipitation method, mixing the obtained metal oxide with the molecular sieve and a binder, forming, and roasting to obtain the oxidation catalyst.
8. The method according to claim 7, characterized in that the preparation of the oxidation catalyst comprises the following specific steps:
(a) The metal oxide is prepared by adopting a coprecipitation method: adding a precipitant into the precursor solution of the metal oxide, drying the obtained precipitate, screening and roasting to obtain the metal oxide;
(b) Mixing metal oxide and/or metal oxide prepared in the step (a) with molecular sieve powder, adding adhesive, adding modified metal precursor solution, kneading, extruding, drying and roasting to obtain the oxidation catalyst.
9. The method for purifying nitrogen-containing volatile organic compounds and NO x in exhaust gas according to claim 8, wherein in step (a):
The precipitant is at least one of sodium hydroxide, sodium carbonate, ammonia water, urea and sodium bicarbonate; and/or the number of the groups of groups,
The pH value of the precursor solution of the metal oxide after adding the precipitant is 7-12; and/or the number of the groups of groups,
The precursor of the metal oxide is selected from water-soluble compounds of the metal, preferably at least one of nitrate, sulfate, hydrochloride and oxalate of the metal; and/or the number of the groups of groups,
The precursor of the modified metal element is selected from water-soluble compounds of the modified metal, preferably at least one of nitrate, sulfate, hydrochloride and oxalate of the modified metal; and/or the number of the groups of groups,
The solvent of the precursor solution is at least one of water, ethanol, methanol, glycol and glycerol; and/or the number of the groups of groups,
The molar concentration of metal ions in the metal oxide precursor solution and the modified metal precursor solution is independently selected from 0.01-10mol/L, preferably 0.1-1mol/L; and/or the number of the groups of groups,
The drying temperature is 60-120 ℃, preferably 80-100 ℃; and/or the number of the groups of groups,
The drying time is 6-48 hours, preferably 12-24 hours; and/or the number of the groups of groups,
The powder particles obtained by sieving are 80-300 meshes, preferably 100-200 meshes; and/or the number of the groups of groups,
The roasting temperature is 300-600 ℃, preferably 400-550 ℃; and/or the number of the groups of groups,
The calcination time is 1 to 12 hours, preferably 4 to 8 hours.
10. The method of claim 8, wherein in step (b):
The weight ratio of the molecular sieve to the metal oxide is (30-80): (70-20), preferably (40-70): (60-30); and/or the number of the groups of groups,
The binder accounts for 1-20% of the total weight of the molecular sieve and the metal oxide, preferably 5-15%; and/or the number of the groups of groups,
The powder particle diameter D90 of the molecular sieve is smaller than 10 microns; and/or the number of the groups of groups,
The drying temperature is 30-120 ℃, preferably 40-60 ℃; and/or the number of the groups of groups,
The drying time is 6-72 hours, preferably 24-48 hours; and/or the number of the groups of groups,
The roasting temperature is 400-700 ℃, preferably 400-600 ℃; and/or the number of the groups of groups,
The calcination time is 1 to 12 hours, preferably 4 to 8 hours.
11. A purification system for purifying a nitrogen-containing volatile organic compound and NO x in an exhaust gas according to any one of claims 1 to 10, characterized in that the purification system comprises, in order from the upstream side on the exhaust gas passage: optionally a gas-liquid separation device, a compressor for bubbling a free oxygen-containing gas into the exhaust gas stream to be purified, a heat exchanger for preheating the exhaust gas stream to be purified and a fixed bed reactor, the discharge of which is optionally in communication with the heat exchanger; the oxidation catalyst is filled in the fixed bed reactor.
12. The purification system of claim 11, wherein: the air inlet pipeline of the heat exchanger is provided with a branch pipeline which is communicated with the air outlet pipeline of the heat exchanger, and an electric heater is connected in parallel.
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