JP4182325B2 - Low temperature denitration catalyst and exhaust gas low temperature denitration method - Google Patents
Low temperature denitration catalyst and exhaust gas low temperature denitration method Download PDFInfo
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- JP4182325B2 JP4182325B2 JP2002147997A JP2002147997A JP4182325B2 JP 4182325 B2 JP4182325 B2 JP 4182325B2 JP 2002147997 A JP2002147997 A JP 2002147997A JP 2002147997 A JP2002147997 A JP 2002147997A JP 4182325 B2 JP4182325 B2 JP 4182325B2
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- exhaust gas
- activated carbon
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- carbon fiber
- catalyst
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- 239000003054 catalyst Substances 0.000 title claims description 50
- 238000000034 method Methods 0.000 title claims description 20
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 63
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical class C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 49
- 239000007789 gas Substances 0.000 claims description 40
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 25
- 229910052751 metal Inorganic materials 0.000 claims description 19
- 239000002184 metal Substances 0.000 claims description 19
- 229910044991 metal oxide Inorganic materials 0.000 claims description 17
- 150000004706 metal oxides Chemical class 0.000 claims description 17
- -1 carbon-bromine compound Chemical class 0.000 claims description 14
- 150000003682 vanadium compounds Chemical class 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 11
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 10
- AMWRITDGCCNYAT-UHFFFAOYSA-L hydroxy(oxo)manganese;manganese Chemical compound [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 claims description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- 239000003638 chemical reducing agent Substances 0.000 claims description 8
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims description 6
- GEYXPJBPASPPLI-UHFFFAOYSA-N manganese(iii) oxide Chemical compound O=[Mn]O[Mn]=O GEYXPJBPASPPLI-UHFFFAOYSA-N 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 239000002918 waste heat Substances 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 238000001179 sorption measurement Methods 0.000 claims description 3
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 description 15
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 15
- 238000006243 chemical reaction Methods 0.000 description 14
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 12
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 9
- 229910052794 bromium Inorganic materials 0.000 description 9
- 239000011572 manganese Substances 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 7
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 6
- 229910021529 ammonia Inorganic materials 0.000 description 6
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 5
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical class [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 150000004687 hexahydrates Chemical class 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- HGUFODBRKLSHSI-UHFFFAOYSA-N 2,3,7,8-tetrachloro-dibenzo-p-dioxin Chemical compound O1C2=CC(Cl)=C(Cl)C=C2OC2=C1C=C(Cl)C(Cl)=C2 HGUFODBRKLSHSI-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 2
- SWLVFNYSXGMGBS-UHFFFAOYSA-N ammonium bromide Chemical compound [NH4+].[Br-] SWLVFNYSXGMGBS-UHFFFAOYSA-N 0.000 description 2
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 235000006408 oxalic acid Nutrition 0.000 description 2
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 description 2
- 229910001935 vanadium oxide Inorganic materials 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910001622 calcium bromide Inorganic materials 0.000 description 1
- WGEFECGEFUFIQW-UHFFFAOYSA-L calcium dibromide Chemical compound [Ca+2].[Br-].[Br-] WGEFECGEFUFIQW-UHFFFAOYSA-L 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- ZMIGMASIKSOYAM-UHFFFAOYSA-N cerium Chemical compound [Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce][Ce] ZMIGMASIKSOYAM-UHFFFAOYSA-N 0.000 description 1
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 1
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 1
- 229910000428 cobalt oxide Inorganic materials 0.000 description 1
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical compound [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- PPNAOCWZXJOHFK-UHFFFAOYSA-N manganese(2+);oxygen(2-) Chemical class [O-2].[Mn+2] PPNAOCWZXJOHFK-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910000480 nickel oxide Inorganic materials 0.000 description 1
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical compound [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000004690 nonahydrates Chemical class 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 229910052815 sulfur oxide Inorganic materials 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 150000003681 vanadium Chemical class 0.000 description 1
- UUUGYDOQQLOJQA-UHFFFAOYSA-L vanadyl sulfate Chemical compound [V+2]=O.[O-]S([O-])(=O)=O UUUGYDOQQLOJQA-UHFFFAOYSA-L 0.000 description 1
- 229940041260 vanadyl sulfate Drugs 0.000 description 1
- 229910000352 vanadyl sulfate Inorganic materials 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
- 238000004056 waste incineration Methods 0.000 description 1
Landscapes
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、低温脱硝用触媒および排ガスの低温脱硝方法に関する。
【０００２】
【従来の技術と発明が解決しようとする課題】
ボイラ等の固定式窒素酸化物発生源の脱硝に関しては、従来から、チタニア等のセラミック材料に酸化バナジウムを担持した触媒を用い、アンモニアを還元剤に用いて窒素酸化物（ＮＯx）を選択的に還元する方法（ＳＣＲ）が広く知られ、実用化されている（「公害防止の技術と法規」五訂、大気編、丸善）。
【０００３】
しかしながら、この触媒を用いる場合には、脱硝活性を上げるために３００℃以上に反応温度を高める必要がある。反応温度を高温にすれば、担体であるチタニアがシンタリングを起こし、触媒性能の低下を引き起こす（三菱重工技報２４，３０９（１９９０））。このため、非常に高価なバナジウム触媒を、頻繁に交換する必要が生じる。
【０００４】
また、高い反応温度が要求されると、脱硝装置も、ボイラ出口直後、廃熱ボイラの伝熱部途中等の限られた個所にしか設置できないため、装置の複雑化、耐熱材料の使用による高額化、交換時の作業性の悪さ等の問題も生じる。
【０００５】
さらに、このような従来技術では、既存の装置の最終出口の低温排ガスや、金属焼結炉、船舶用ディーゼル等の低温排ガスの脱硝に適用しようとすると再加熱が必要となり、経済的な見地よりその適用は事実上困難である。
【０００６】
また、ごみ焼却場の排ガスは、ダイオキシン類の排出対策のためにバグフィルター温度を１５０℃以下に低温化することが求められているが、この後工程で脱硝するために排ガスの再加熱が必要であり、経済的に大きな問題となっている。
【０００７】
そこで、低温でも作動する触媒の研究も多く実施されており、特開平６−３２７９７５には活性炭にバナジウム化合物および臭素化合物を担持した触媒が、特開平９−１９２４９１には炭素質材料にバナジウム、臭素、銅、ランタン、セリウム、モリブデン、タングステン等の化合物を担持した触媒が、低温でのアンモニア還元脱硝に効果があると開示されている。しかしながら、これらの触媒は、反応温度が常温以上１００℃以下の低温域でのみ働き、１５０℃以上の中低温では寿命が短時間に終わるという欠点がある。一方、ボイラ等の固定発生源では、煙突出口から白煙を見えないようにするため、排ガス温度を１５０℃以上とするのが一般的である。また、排ガス中の窒素酸化物や硫黄酸化物が水蒸気と共に凝縮すると、排気ダクトの酸腐食を引き起こすので、最終排ガスの温度が１５０℃以上のものが汎用となっている。従って、そのような温度で長時間耐久性のある触媒が求められている。
【０００８】
本発明は、ボイラ等の固定式窒素酸化物発生源の脱硝を、２００℃以下の低温で行う技術を提供することを目的とする。
【０００９】
【課題を解決するための手段】
本発明者は、上記課題を解決すべく鋭意研究を重ねた結果、特定の構成からなる触媒を一定条件下で用いる場合には、低温下でも有効に脱硝できることを見出し、本発明を完成するに至った。
【００１０】
すなわち、本発明は、下記に示すとおりの低温脱硝用触媒および排ガスの低温脱硝方法を提供するものである。
項１． マンガン、鉄、コバルトおよびニッケルからなる群より選択される少なくとも１種の金属の酸化物を担持させた活性炭素繊維と、バナジウム化合物を担持させた活性炭素繊維とを、混合してなる低温脱硝用触媒。
項２． 金属の酸化物が、二酸化マンガン、三酸化二マンガンおよび四酸化三マンガンからなる群より選択される少なくとも１種である項１に記載の低温脱硝用触媒。
項３． 活性炭素繊維が、窒素吸着により求めたＢＥＴ比表面積が５００〜１５００ｍ2／ｇのピッチ系活性炭素繊維である項１または２に記載の低温脱硝用触媒。
項４． 活性炭素繊維上に炭素−臭素化合物を形成してなる項１〜３のいずれかに記載の低温脱硝用触媒。
項５． 項１〜４のいずれかに記載の触媒に、窒素酸化物を含む排ガスを還元剤の存在下で接触させることを特徴とする排ガスの低温脱硝方法。
項６． 窒素酸化物を含む排ガスが、窒素酸化物１０〜５０００ｐｐｍ、酸素３ｖｏｌ％以上および水蒸気３０ｖｏｌ％以下を含有し、且つ、該排ガスの温度が２００℃以下である項５に記載の排ガスの低温脱硝方法。
項７． 窒素酸化物を含む排ガスが、排煙処理装置出口または廃熱ボイラ出口における排ガスである項５または６に記載の排ガスの低温脱硝方法。
【００１１】
【発明の実施の形態】
本発明の低温脱硝用触媒は、マンガン（Ｍｎ）、鉄（Ｆｅ）、コバルト（Ｃｏ）およびニッケル（Ｎｉ）からなる群より選択される少なくとも１種の金属の酸化物を担持させた活性炭素繊維と、バナジウム（Ｖ）化合物を担持させた活性炭素繊維とを、混合してなるものである。
【００１２】
金属酸化物担持活性炭素繊維
担持させる金属酸化物としては、マンガン酸化物（ＭｎＯ2、ＭｎＯ、Ｍｎ2Ｏ3、Ｍｎ3Ｏ4等）、鉄酸化物（Ｆｅ2Ｏ3、Ｆｅ3Ｏ4等）、コバルト酸化物（Ｃｏ2Ｏ3等）およびニッケル酸化物（ＮｉＯ等）の少なくとも１種を用いることができ、これらの酸化物の中においては、本発明の効果が得られる限り特にその酸化物の種類は制限されない。これらの中でも、二酸化マンガン（ＭｎＯ2）、三酸化二マンガン（Ｍｎ2Ｏ3）、四酸化三マンガン（Ｍｎ3Ｏ4）等のマンガン酸化物が好ましい。金属酸化物の担持量は、最終製品の用途等に応じて適宜変更できるが、活性炭素繊維に対して５〜３０重量％程度が好ましく、１０〜２０重量％程度がより好ましい。
【００１３】
活性炭素繊維としては、金属酸化物を担持できる限り特に制限されず、公知のピッチ系、ＰＡＮ系等のものが使用でき、また市販の活性炭素繊維も使用することができる。この中でも、特にピッチ系活性炭素繊維が、長期間の使用における安定性の点から好ましい。また、活性炭素繊維の比表面積（窒素吸着により求めたＢＥＴ比表面積）は、最終製品の用途等に応じて適宜設定することができるが、５００〜１５００ｍ2／ｇ程度が好ましく、７００〜１０００ｍ2／ｇ程度がより好ましい。特に、細孔径が２ｎｍ以下の微細なミクロポアを多く有する活性炭素繊維が好ましい。
【００１４】
本発明の低温脱硝用触媒の一部を構成する、金属酸化物を担持させた活性炭素繊維は、例えば次の方法により製造することができる。まず、Ｍｎ、Ｆｅ、ＣｏおよびＮｉの少なくとも１種の金属塩の水溶液を活性炭素繊維に含浸し、減圧脱気した後、乾燥し、次いで空気等の酸化性雰囲気下２００〜３００℃で加熱処理して当該金属塩を金属酸化物とする。
【００１５】
上記金属塩としては、水溶性のものであれば特に制限されないが、硝酸塩（例えば、硝酸マンガン（II）、硝酸鉄（III）等）を用いることが好ましい。これら金属塩には、水和物も含まれる。
【００１６】
なお、金属酸化物を担持させる前に、活性炭素繊維に臭素化合物を添加し、炭素−臭素化合物を形成してもよい。その方法は、例えば、臭化アンモニウム、臭化ナトリウム、臭化カリウム、臭化カルシウム等の臭素化合物の水溶液を活性炭素繊維に含浸し、８０〜１１０℃で乾燥して活性炭素繊維上に炭素−臭素化合物を形成する。活性炭素繊維への臭素の添加量は、炭素に対して５〜３０重量％程度が好ましく、１０〜２０重量％程度がより好ましい。
【００１７】
バナジウム化合物担持活性炭素繊維
担持させるバナジウム化合物としては、３価、４価および５価のいずれかのバナジウムの酸化物、無機酸塩または有機酸塩を用いることができる。メタバナジン酸アンモニウムをシュウ酸で還元したものや、硫酸バナジルを好適に用いることができる。バナジウム化合物の担持量は、最終製品の用途等に応じて適宜変更できるが、活性炭素繊維に対して１〜１０重量％程度が好ましく、１．５〜５重量％程度がより好ましい。
【００１８】
活性炭素繊維としては、上記金属酸化物を担持するものと同様のものを用いることができる。
【００１９】
本発明の低温脱硝用触媒の一部を構成する、バナジウム化合物を担持させた活性炭素繊維は、例えば次の方法により製造することができる。まず、バナジウム化合物の水溶液を活性炭素繊維に含浸し、減圧脱気した後、乾燥し、次いで窒素等の不活性雰囲気下４００〜５００℃で加熱処理してバナジウム化合物担持活性炭素繊維を得ることができる。
【００２０】
なお、バナジウム化合物を担持させる前に、上記と同様にして、活性炭素繊維に臭素化合物を添加し、炭素−臭素化合物を形成してもよい。
【００２１】
上記のようにして得られる金属酸化物担持活性炭素繊維とバナジウム化合物担持活性炭素繊維とを物理的に混合することにより、本発明の低温脱硝用触媒が得られる。混合割合（重量比）は、金属酸化物担持活性炭素繊維：バナジウム化合物担持活性炭素繊維＝１：０．５〜１．５であるのが好ましく、１：０．８〜１．１であるのがより好ましい。
【００２２】
排ガスの低温脱硝方法
本発明の排ガスの低温脱硝方法は、上記の本発明の低温脱硝用触媒に、窒素酸化物を含む排ガスを還元剤の存在下で接触させることを特徴とする。
【００２３】
本発明方法では、還元剤の存在下で窒素酸化物を含む排ガスと触媒との接触を行うが、還元剤としては公知のものをそのまま使用でき、例えば、アンモニア、水素、炭化水素等が使用できる。この中でも、特にアンモニアが好ましい。還元剤の使用量は、上記排ガス中の窒素酸化物の含有量と等モルまたはそれ以上の量とすればよい。
【００２４】
窒素酸化物を含む排ガスの組成は、排気ガス等の組成のままでもよいが、特に窒素酸化物１０〜５０００ｐｐｍ（好ましくは２０〜１０００ｐｐｍ）、酸素３ｖｏｌ％以上（好ましくは３〜１５ｖｏｌ％）および水蒸気（水分）３０ｖｏｌ％以下（好ましくは０〜１５ｖｏｌ％）を含む組成であることが好ましい。また、接触させる際の温度も特に制限されないが、２００℃以下であるのが好ましく、１００〜２００℃であるのがより好ましい。
【００２５】
接触させる方法は、特に制限されず、公知の方法に従えばよい。例えば、触媒を反応管等に充填し、その中に窒素酸化物を含む排ガスを流通させればよい。このガスの流通量は、用いる触媒量等に応じて適宜定めることができる。
【００２６】
本発明においては、低温脱硝用触媒を通過する間に、ガス中に含まれる窒素酸化物（ＮＯx）が、還元剤（例えばアンモニア（ＮＨ3））と反応し、無害な窒素（Ｎ2）と水蒸気（Ｈ2Ｏ）に分解される。反応式は、以下の（１）、（２）の通りである。
ＮＯ＋1/2Ｏ２→ＮＯ2 （１）
（金属酸化物担持活性炭素繊維触媒）
６ＮＯ2＋８ＮＨ3→７Ｎ2＋１２Ｈ2Ｏ （２）
（バナジウム化合物担持活性炭素繊維触媒）
すなわち、活性炭素繊維の表面の金属酸化物にＮＯが吸着され、金属酸化物の強い酸化性能によりＮＯ2となる。生成した反応性の高いＮＯ2が、バナジウム化合物担持活性炭素繊維上でアンモニアと反応し、Ｎ2とＨ2Ｏに還元される。Ｎ2とＨ2Ｏが脱離した後の金属酸化物は酸素により酸化され、酸化性金属酸化物表面が再生される。これらの反応が２００℃以下の低温で進行するのは、特に、活性炭素繊維が大きな比表面積を有することと、活性炭素繊維の有する２ｎｍ以下のミクロポア中でこれらの反応物質が凝縮し、ミクロな領域で高圧反応するためである。
【００２７】
【発明の効果】
本発明の低温脱硝用触媒は、安価で長寿命な脱硝触媒である。
【００２８】
本発明の低温脱硝用触媒を用いれば、２００℃以下の温度で、低〜高濃度の窒素酸化物を、高い除去率で脱硝することができる。
【００２９】
また、本発明の低温脱硝用触媒を用いれば、１５０℃以下の低温でも脱硝ができるので、既存のバナジウム触媒に換えて用いると、触媒の寿命が大幅に改善され、脱硝装置に係るコストが大きく削減できる。
【００３０】
本発明の低温脱硝方法は、ボイラ、エンジン、タービン等から排出される燃焼排気ガスの脱硝に有効であり、特に排煙処理装置、廃熱回収装置等の出口における比較的低温（通常２００℃以下）の排気ガスを効率良く脱硝することができる。
【００３１】
さらに、本発明の低温脱硝方法を用いれば、排煙脱硝装置の設置位置を自由にできる。例えば、空気予熱器出口や、集塵機出口、さらには最終出口である煙突内部にも脱硝装置の設置が可能になる。従って、既存の脱硝装置出口における低温ガス中の窒素酸化物のより高度な脱硝が可能になり、環境負荷のさらなる低減が図れる。
【００３２】
また、既存の脱硝装置の適用が困難な金属焼結炉や船舶用ディーゼル、ダイオキシン対策用低温バグフィルター出口における再加熱不要の脱硝が可能になる。
【００３３】
【実施例】
以下、実施例を示し、本発明の特徴をより一層明確にする。
【００３４】
実施例１〜４
活性炭素繊維としては、ピッチ系活性炭素繊維（アドール(株)製）を用いた。試料名は「Ａ７」であり、その比表面積は７００ｍ2／ｇである。このピッチ系活性炭素繊維に、硝酸マンガン（II）６水和物、硝酸鉄（III）９水和物、硝酸コバルト（II）６水和物または硝酸ニッケル（II）６水和物の水溶液をそれぞれ含浸させた。含浸させた水溶液の濃度は、最終的な金属担持量として５〜２０重量％の範囲となるように調整した。
【００３５】
その後、デシケーター内で室温下、真空ポンプにより５０Ｐａまで減圧し、各試料について脱気処理を施した。この処理によって、活性炭素繊維のミクロポア内への脱気と金属塩の浸透を促進することができる。次いで、これを１００℃の熱風下で１昼夜乾燥し、さらに、空気気流下、２００〜３００℃で１時間加熱処理し、上記金属硝酸塩を熱分解して金属酸化物担持活性炭素繊維を得た。
【００３６】
同様に、ピッチ系活性炭素繊維「Ａ７」を用い、このピッチ系活性炭素繊維に、メタバナジン酸アンモニウムをシュウ酸で還元したものの水溶液を含浸させた。含浸させた水溶液の濃度は、最終的なバナジウム担持量として１〜１０重量％の範囲となるように調整した。上記の金属酸化物担持と同様に脱気処理、乾燥を行い、次に、窒素気流中、４５０℃で５時間加熱処理し、バナジウム塩を分解してバナジウム化合物担持活性炭素繊維を得た。
【００３７】
次いで、金属酸化物担持活性炭素繊維とバナジウム化合物担持活性炭素繊維を、重量比で１：１となるように物理的に混合し、低温脱硝用触媒を得た。
【００３８】
実施例５
ピッチ系活性炭素繊維「Ａ７」に、臭化アンモニウム水溶液を予め含浸させ、１００℃の熱風下で１昼夜乾燥し、炭素−臭素化合物を形成させた後、実施例１と同様にして金属（Ｍｎ）酸化物担持およびバナジウム化合物担持をそれぞれ行った。活性炭素繊維への臭素の添加量は、炭素に対して２０重量％となるようにした。得られた金属酸化物担持活性炭素繊維とバナジウム化合物担持活性炭素繊維を、重量比で１：１となるように物理的に混合し、低温脱硝用触媒を得た。
【００３９】
次に、得られた低温脱硝用触媒を反応管（内径１５ｍｍ）に２．５ｇを充填し、温度１００〜１７０℃でガスを５００ｍｌ／ｍｉｎで流通した。ガス組成は、ＮＯ：２００ｐｐｍ、ＮＨ3：２００ｐｐｍ、Ｏ2：１２．６ｖｏｌ％、Ｎ2：バランス、水分：１２．２ｖｏｌ％とした。
【００４０】
反応管より出口ガスを、化学発光式ＮＯx計（柳本製作所(株)製、「ＥＣＬ−８８ＵＳ」）により分析し、次式により脱硝率を算出した。
脱硝率（％）＝［（入口ＮＯ濃度(ppm)−出口ＮＯ濃度(ppm)）／入口ＮＯ濃度(ppm)］×１００
表１に、実施例１〜５で得られた低温脱硝用触媒の脱硝率を示す。
【００４１】
なお、脱硝率は、各温度で反応開始後３０時間後の安定化した状態の定常反応中における値を示す。
【００４２】
【表１】
比較例１〜４
比較例として、ピッチ系活性炭素繊維「Ａ７」のみ、金属（Ｍｎ）酸化物のみを担持した触媒、バナジウム化合物のみを担持した触媒、臭素化合物を添加（炭素に対して２０重量％）したバナジウム化合物担持触媒を用いて、上記と同様にして脱硝反応を行った。結果を表２に示す。
【００４４】
【表２】
表１に示す通り、金属酸化物担持活性炭素繊維とバナジウム化合物担持活性炭素繊維を混合した低温脱硝用触媒を用いると、１００〜１７０℃の低温域で高い脱硝率を示した。特に、金属酸化物がＭｎ酸化物の場合には、１００〜１７０℃の低温域で安定して９０％以上の脱硝率を示した。
【００４６】
これに対し、表２に示す通り、活性炭素繊維のみの場合やバナジウム化合物のみを担持した場合は、全般的に脱硝率が低かった。金属酸化物のみを担持した触媒は、１２０℃以下の低温での脱硝活性が低かった。臭素化合物を添加したバナジウム化合物担持触媒は、１５０℃以上での安定性が低く、脱硝率が徐々に低下する傾向が見られた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low-temperature denitration catalyst and a low-temperature denitration method for exhaust gas.
[0002]
[Prior art and problems to be solved by the invention]
For denitration of stationary nitrogen oxide sources such as boilers, traditionally, a catalyst in which vanadium oxide is supported on a ceramic material such as titania is used, and nitrogen oxide (NO x ) is selectively used using ammonia as a reducing agent. (SCR) is widely known and put into practical use (“Pollution Prevention Technology and Regulations”, 5th edition, Atmosphere, Maruzen).
[0003]
However, when this catalyst is used, it is necessary to increase the reaction temperature to 300 ° C. or higher in order to increase the denitration activity. When the reaction temperature is increased, titania as a support causes sintering, which causes a decrease in catalyst performance (Mitsubishi Heavy Industries Technical Report 24, 309 (1990)). This necessitates frequent replacement of very expensive vanadium catalysts.
[0004]
In addition, when a high reaction temperature is required, a denitration device can be installed only in a limited area, such as immediately after the boiler outlet, in the middle of the heat transfer section of the waste heat boiler, etc., which increases the complexity of the device and the use of heat-resistant materials. Problems such as poor workability at the time of conversion and replacement also occur.
[0005]
Furthermore, in such a conventional technology, reheating is required if it is applied to low-temperature exhaust gas at the final outlet of existing equipment, or low-temperature exhaust gas from a metal sintering furnace, marine diesel, etc. Its application is practically difficult.
[0006]
In addition, it is required to reduce the bag filter temperature to 150 ° C or lower for the waste incineration waste gas to prevent dioxin emissions, but it is necessary to reheat the exhaust gas in order to denitrate in the subsequent process. This is a major economic problem.
[0007]
Therefore, many studies have been conducted on catalysts that operate even at low temperatures. JP-A-6-327975 discloses a catalyst in which vanadium compounds and bromine compounds are supported on activated carbon, and JP-A-9-192491 discloses vanadium, bromine as carbonaceous materials. It is disclosed that a catalyst supporting a compound such as copper, lanthanum, cerium, molybdenum and tungsten is effective for ammonia reduction denitration at low temperatures. However, these catalysts have a disadvantage that they work only in a low temperature range where the reaction temperature is normal temperature or higher and 100 ° C. or lower, and that the lifetime ends in a short time at medium and low temperatures of 150 ° C. or higher. On the other hand, in a fixed generation source such as a boiler, the exhaust gas temperature is generally set to 150 ° C. or higher so that white smoke cannot be seen from the smoke outlet. Further, when nitrogen oxides or sulfur oxides in the exhaust gas are condensed together with water vapor, acid corrosion of the exhaust duct is caused, so that the exhaust gas having a temperature of 150 ° C. or higher is widely used. Accordingly, there is a need for catalysts that are durable for long periods of time at such temperatures.
[0008]
An object of the present invention is to provide a technique for performing denitration of a fixed nitrogen oxide generation source such as a boiler at a low temperature of 200 ° C. or lower.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventor has found that when a catalyst having a specific configuration is used under a certain condition, it can be effectively denitrated even at a low temperature, thereby completing the present invention. It came.
[0010]
That is, the present invention provides a catalyst for low temperature denitration and a method for low temperature denitration of exhaust gas as described below.
Item 1. Low temperature denitration obtained by mixing an activated carbon fiber carrying an oxide of at least one metal selected from the group consisting of manganese, iron, cobalt and nickel and an activated carbon fiber carrying a vanadium compound catalyst.
Item 2. Item 2. The low-temperature denitration catalyst according to Item 1, wherein the metal oxide is at least one selected from the group consisting of manganese dioxide, dimanganese trioxide and trimanganese tetroxide.
Item 3. Item 3. The low-temperature denitration catalyst according to Item 1 or 2, wherein the activated carbon fiber is a pitch-based activated carbon fiber having a BET specific surface area of 500 to 1500 m 2 / g determined by nitrogen adsorption.
Item 4. Item 4. The low-temperature denitration catalyst according to any one of Items 1 to 3, wherein a carbon-bromine compound is formed on activated carbon fibers.
Item 5. Item 5. A method for low-temperature denitration of exhaust gas, comprising contacting the catalyst according to any one of Items 1 to 4 with exhaust gas containing nitrogen oxides in the presence of a reducing agent.
Item 6. Item 6. The method for low-temperature denitration of exhaust gas according to Item 5, wherein the exhaust gas containing nitrogen oxide contains 10 to 5000 ppm of nitrogen oxide, 3 vol% or more of oxygen and 30 vol% or less of water vapor, and the temperature of the exhaust gas is 200 ° C or less. .
Item 7. Item 7. The low-temperature denitration method for exhaust gas according to Item 5 or 6, wherein the exhaust gas containing nitrogen oxides is exhaust gas at the exhaust gas treatment device outlet or the waste heat boiler outlet.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The low-temperature denitration catalyst of the present invention is an activated carbon fiber carrying at least one metal oxide selected from the group consisting of manganese (Mn), iron (Fe), cobalt (Co), and nickel (Ni). And an activated carbon fiber carrying a vanadium (V) compound.
[0012]
As the metal oxide-supported activated carbon fiber <br/> metal oxide to be supported include manganese oxide (MnO 2, MnO, Mn 2 O 3, Mn 3 O 4 , etc.), iron oxide (Fe 2 O 3, Fe 3 O 4 etc.), cobalt oxide (Co 2 O 3 etc.) and nickel oxide (NiO etc.) can be used, and the effects of the present invention can be obtained in these oxides. As long as the type of the oxide is not particularly limited. Among these, manganese oxides such as manganese dioxide (MnO 2 ), dimanganese trioxide (Mn 2 O 3 ), and trimanganese tetroxide (Mn 3 O 4 ) are preferable. The amount of the metal oxide supported can be appropriately changed according to the use of the final product, but is preferably about 5 to 30% by weight, more preferably about 10 to 20% by weight with respect to the activated carbon fiber.
[0013]
The activated carbon fiber is not particularly limited as long as it can carry a metal oxide, and known pitch-based and PAN-based materials can be used, and commercially available activated carbon fibers can also be used. Among these, pitch-based activated carbon fibers are particularly preferable from the viewpoint of stability in long-term use. The specific surface area of the activated carbon fiber (BET specific surface area determined by nitrogen adsorption) can be appropriately set according to the use of the final product, etc., but is preferably about 500 to 1500 m 2 / g, and preferably 700 to 1000 m 2. / G is more preferable. In particular, activated carbon fibers having many fine micropores having a pore diameter of 2 nm or less are preferable.
[0014]
The activated carbon fiber carrying a metal oxide and constituting a part of the low-temperature denitration catalyst of the present invention can be produced, for example, by the following method. First, an activated carbon fiber is impregnated with an aqueous solution of at least one metal salt of Mn, Fe, Co, and Ni, degassed under reduced pressure, dried, and then heated at 200 to 300 ° C. in an oxidizing atmosphere such as air. Then, the metal salt is used as a metal oxide.
[0015]
The metal salt is not particularly limited as long as it is water-soluble, but nitrates (for example, manganese (II) nitrate, iron (III) nitrate, etc.) are preferably used. These metal salts include hydrates.
[0016]
In addition, before carrying | supporting a metal oxide, a bromine compound may be added to activated carbon fiber and a carbon-bromine compound may be formed. The method includes, for example, impregnating an activated carbon fiber with an aqueous solution of a bromine compound such as ammonium bromide, sodium bromide, potassium bromide, calcium bromide, and drying at 80 to 110 ° C. A bromine compound is formed. The amount of bromine added to the activated carbon fiber is preferably about 5 to 30% by weight, more preferably about 10 to 20% by weight, based on carbon.
[0017]
Vanadium compound-supported activated carbon fiber As the vanadium compound to be supported , any of trivalent, tetravalent and pentavalent vanadium oxides, inorganic acid salts or organic acid salts can be used. A product obtained by reducing ammonium metavanadate with oxalic acid or vanadyl sulfate can be suitably used. The amount of the vanadium compound supported can be appropriately changed according to the use of the final product, but is preferably about 1 to 10% by weight, more preferably about 1.5 to 5% by weight with respect to the activated carbon fiber.
[0018]
As the activated carbon fiber, the same one as that supporting the metal oxide can be used.
[0019]
The activated carbon fiber carrying a vanadium compound and constituting a part of the low-temperature denitration catalyst of the present invention can be produced, for example, by the following method. First, an activated carbon fiber is impregnated with an aqueous solution of a vanadium compound, degassed under reduced pressure, dried, and then heat-treated at 400 to 500 ° C. in an inert atmosphere such as nitrogen to obtain a vanadium compound-supported activated carbon fiber. it can.
[0020]
In addition, before carrying | supporting a vanadium compound, you may add a bromine compound to activated carbon fiber similarly to the above, and may form a carbon-bromine compound.
[0021]
The low-temperature denitration catalyst of the present invention is obtained by physically mixing the metal oxide-supported activated carbon fiber and the vanadium compound-supported activated carbon fiber obtained as described above. The mixing ratio (weight ratio) is preferably metal oxide-supported activated carbon fiber: vanadium compound-supported activated carbon fiber = 1: 0.5 to 1.5, and 1: 0.8 to 1.1. Is more preferable.
[0022]
Low-temperature denitration method for exhaust gas The low-temperature denitration method for exhaust gas according to the present invention is characterized in that the low-temperature denitration catalyst according to the present invention is brought into contact with exhaust gas containing nitrogen oxides in the presence of a reducing agent. .
[0023]
In the method of the present invention, the exhaust gas containing nitrogen oxides is brought into contact with the catalyst in the presence of a reducing agent, but known reducing agents can be used as they are, for example, ammonia, hydrogen, hydrocarbons, etc. can be used. . Among these, ammonia is particularly preferable. The amount of the reducing agent used may be an equimolar amount or more than the nitrogen oxide content in the exhaust gas.
[0024]
The composition of the exhaust gas containing nitrogen oxides may be the composition of exhaust gas or the like, but in particular, nitrogen oxides are 10 to 5000 ppm (preferably 20 to 1000 ppm), oxygen is 3 vol% or more (preferably 3 to 15 vol%), and water vapor. (Moisture) It is preferable that it is a composition containing 30 vol% or less (preferably 0-15 vol%). Moreover, the temperature at the time of making it contact in particular is although it does not restrict | limit, It is preferable that it is 200 degrees C or less, and it is more preferable that it is 100-200 degreeC.
[0025]
The method for contacting is not particularly limited, and may be a known method. For example, the catalyst may be filled in a reaction tube or the like, and exhaust gas containing nitrogen oxides may be circulated therein. The amount of gas flow can be determined as appropriate according to the amount of catalyst used.
[0026]
In the present invention, nitrogen oxide (NO x ) contained in the gas reacts with a reducing agent (for example, ammonia (NH 3 )) while passing through the low-temperature denitration catalyst, and harmless nitrogen (N 2 ). And water vapor (H 2 O). The reaction formula is as follows (1) and (2).
NO + 1 / 2O2 → NO 2 (1)
(Metal oxide-supported activated carbon fiber catalyst)
6NO 2 + 8NH 3 → 7N 2 + 12H 2 O (2)
(Vanadium compound-supported activated carbon fiber catalyst)
That is, NO is adsorbed on the metal oxide on the surface of the activated carbon fiber, and becomes NO 2 due to the strong oxidation performance of the metal oxide. The produced highly reactive NO 2 reacts with ammonia on the vanadium compound-supported activated carbon fiber and is reduced to N 2 and H 2 O. The metal oxide after N 2 and H 2 O are desorbed is oxidized by oxygen, and the surface of the oxidizable metal oxide is regenerated. These reactions proceed at a low temperature of 200 ° C. or lower, especially because activated carbon fibers have a large specific surface area, and these reactants condense in micropores of 2 nm or less of activated carbon fibers. This is because high pressure reaction occurs in the region.
[0027]
【The invention's effect】
The low-temperature denitration catalyst of the present invention is a denitration catalyst that is inexpensive and has a long life.
[0028]
If the low-temperature denitration catalyst of the present invention is used, low to high concentration nitrogen oxides can be denitrated with a high removal rate at a temperature of 200 ° C. or lower.
[0029]
In addition, if the low-temperature denitration catalyst of the present invention is used, denitration can be performed even at a low temperature of 150 ° C. or lower. Therefore, when used in place of the existing vanadium catalyst, the life of the catalyst is greatly improved, and the cost associated with the denitration apparatus is large. Can be reduced.
[0030]
The low-temperature denitration method of the present invention is effective for denitration of combustion exhaust gas discharged from boilers, engines, turbines, etc., and is relatively low temperature (usually 200 ° C. or less at the outlets of flue gas treatment devices, waste heat recovery devices, etc.). ) Can be efficiently denitrated.
[0031]
Furthermore, if the low temperature denitration method of this invention is used, the installation position of a flue gas denitration apparatus can be made free. For example, it is possible to install a denitration device in an air preheater outlet, a dust collector outlet, and a chimney that is the final outlet. Therefore, it is possible to perform more advanced denitration of nitrogen oxides in the low temperature gas at the exit of the existing denitration apparatus, thereby further reducing the environmental load.
[0032]
In addition, it is possible to perform denitration without reheating at the exit of a metal sintering furnace, marine diesel, or a low-temperature bag filter for dioxin countermeasures, which is difficult to apply an existing denitration apparatus.
[0033]
【Example】
Hereinafter, an example is shown and the feature of the present invention is clarified further.
[0034]
Examples 1-4
Pitch-based activated carbon fiber (manufactured by Adol Co., Ltd.) was used as the activated carbon fiber. The sample name is “A7”, and the specific surface area is 700 m 2 / g. An aqueous solution of manganese nitrate (II) hexahydrate, iron nitrate (III) nonahydrate, cobalt nitrate (II) hexahydrate or nickel nitrate (II) hexahydrate is added to this pitch-based activated carbon fiber. Each was impregnated. The concentration of the impregnated aqueous solution was adjusted to be in the range of 5 to 20% by weight as the final metal loading.
[0035]
Thereafter, the pressure was reduced to 50 Pa with a vacuum pump in a desiccator at room temperature, and each sample was deaerated. By this treatment, degassing of activated carbon fibers into the micropores and penetration of the metal salt can be promoted. Next, this was dried for 1 day under hot air at 100 ° C., and further heat-treated at 200 to 300 ° C. for 1 hour under an air stream to thermally decompose the metal nitrate to obtain a metal oxide-supported activated carbon fiber. .
[0036]
Similarly, pitch-based activated carbon fiber “A7” was used, and this pitch-based activated carbon fiber was impregnated with an aqueous solution of ammonium metavanadate reduced with oxalic acid. The concentration of the impregnated aqueous solution was adjusted to be in the range of 1 to 10% by weight as the final vanadium loading. Deaeration treatment and drying were performed in the same manner as the above metal oxide support, followed by heat treatment at 450 ° C. for 5 hours in a nitrogen stream to decompose the vanadium salt to obtain a vanadium compound-supported activated carbon fiber.
[0037]
Next, the metal oxide-supported activated carbon fiber and the vanadium compound-supported activated carbon fiber were physically mixed at a weight ratio of 1: 1 to obtain a low-temperature denitration catalyst.
[0038]
Example 5
Pitch-based activated carbon fiber “A7” was impregnated with an aqueous ammonium bromide solution in advance and dried for 1 day under hot air at 100 ° C. to form a carbon-bromine compound. ) Oxide support and vanadium compound support were performed. The amount of bromine added to the activated carbon fiber was 20% by weight with respect to the carbon. The obtained metal oxide-supported activated carbon fiber and vanadium compound-supported activated carbon fiber were physically mixed at a weight ratio of 1: 1 to obtain a low-temperature denitration catalyst.
[0039]
Next, 2.5 g of the obtained low-temperature denitration catalyst was filled in a reaction tube (inner diameter 15 mm), and gas was circulated at a temperature of 100 to 170 ° C. at 500 ml / min. The gas composition was NO: 200 ppm, NH 3 : 200 ppm, O 2 : 12.6 vol%, N 2 : balance, moisture: 12.2 vol%.
[0040]
The outlet gas from the reaction tube, chemiluminescence NO x meter (Yanagimoto Co., "ECL-88US") was analyzed by was calculated NOx removal efficiency by the following equation.
Denitration rate (%) = [(Inlet NO concentration (ppm) −Outlet NO concentration (ppm)) / Inlet NO concentration (ppm)] × 100
Table 1 shows the denitration rates of the low-temperature denitration catalysts obtained in Examples 1 to 5.
[0041]
The denitration rate indicates a value during a steady-state reaction in a stabilized state 30 hours after the start of the reaction at each temperature.
[0042]
[Table 1]
Comparative Examples 1-4
As comparative examples, only pitch-based activated carbon fiber “A7”, a catalyst supporting only a metal (Mn) oxide, a catalyst supporting only a vanadium compound, and a vanadium compound added with a bromine compound (20% by weight with respect to carbon) Using the supported catalyst, a denitration reaction was performed in the same manner as described above. The results are shown in Table 2.
[0044]
[Table 2]
As shown in Table 1, when a low-temperature denitration catalyst in which metal oxide-supported activated carbon fibers and vanadium compound-supported activated carbon fibers were used, a high denitration rate was exhibited at a low temperature range of 100 to 170 ° C. In particular, when the metal oxide was Mn oxide, the denitration rate was 90% or more stably in a low temperature range of 100 to 170 ° C.
[0046]
On the other hand, as shown in Table 2, when only the activated carbon fiber or only the vanadium compound was supported, the denitration rate was generally low. The catalyst supporting only the metal oxide had low denitration activity at a low temperature of 120 ° C. or lower. The vanadium compound-supported catalyst to which the bromine compound was added had a low stability at 150 ° C. or higher, and the denitration rate tended to decrease gradually.
Claims (7)
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| CN104056658B (en) * | 2014-07-02 | 2017-01-11 | 西安华大骄阳绿色科技有限公司 | Low-temperature sulfur-resistant denitration catalyst and preparing method thereof |
| CN108479795A (en) * | 2018-03-16 | 2018-09-04 | 济宁市兖州区东方化工有限公司 | A kind of desulphurization denitration catalyst and manufacture craft |
| WO2020161875A1 (en) * | 2019-02-07 | 2020-08-13 | 中国電力株式会社 | Combustion system |
| WO2020161874A1 (en) * | 2019-02-07 | 2020-08-13 | 中国電力株式会社 | Combustion system |
| CN109999829A (en) * | 2019-04-30 | 2019-07-12 | 常州大学 | A kind of bimetallic manganese iron low temperature SCR denitration catalyst, preparation method and applications |
| CN112774688A (en) * | 2019-11-08 | 2021-05-11 | 四川大学 | Nano manganese-based oxide low-temperature denitration catalyst and application thereof |
| CN114130119B (en) * | 2021-10-19 | 2023-10-03 | 安徽元琛环保科技股份有限公司 | Preparation method and application of filter material with dust removal, denitration and dioxin removal functions |
| CN113996289B (en) * | 2021-11-12 | 2023-08-18 | 国能龙源催化剂江苏有限公司 | Hollow carbon sphere denitration catalyst for low-temperature flue gas and preparation method thereof |
| CN114602488A (en) * | 2022-01-14 | 2022-06-10 | 南昌大学 | Denitration catalyst and preparation method and application thereof |
| CN115945198B (en) * | 2023-01-31 | 2023-10-24 | 太原理工大学 | Preparation method and application of low-temperature ammonium bisulfate-resistant layered iron-vanadium composite oxide denitration catalyst |
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