云南大學(xué)學(xué)報(自然科學(xué)版),200426(2):159-161CN53-1045/ N ISSN0258-7971Journal of Yunnan University乙醇燃料車尾氣凈化催化劑研究王偉,涂學(xué)炎,張世鴻云南大學(xué)化學(xué)與材料工程學(xué)院,云南昆明650091)摘要制備了一種具有鈣態(tài)礦結(jié)構(gòu)的Ag修飾的L4.6S04Mnk催化劑實驗表明這種催化劑對低濃度乙醇完全氧化的催化活性高于負(fù)載型貴金屬催化劑,O2-TPD譜表明,Ag對126 Sro mNo3表面的修飾可以增加催化劑表而O/O物種的量,從而有利于對乙醇的完全催化氧化關(guān)鍵詞:完全催化氧化;廢氣;乙醇;催化劑中圖分類號:O643.36文獻(xiàn)標(biāo)識碼:A文章編號:0258-7971(2004)02-0159-03乙醇作為車用燃料已有很長的歷史,隨著的催化劑試樣Ag/L206Sm04MnO2;后經(jīng)壓片、再破世界石油價格的提高,我國也日益關(guān)注乙醇汽油車碎篩分出直徑約為021~0.15mm的催化劑備的開發(fā),目前國家已經(jīng)制定了相關(guān)的規(guī)劃,在部分用將計算量的Ag,Pd和Pt的相應(yīng)硝酸鹽溶液按地區(qū)開始推廣乙醇汽油車.乙醇燃料車尾氣污染的等容浸漬法分別浸漬負(fù)載于y-A2O載體上,經(jīng)消除是其實用化必須解決的關(guān)鍵技術(shù)之一,汽、柴陳放10h,393K烘于4h,773K空氣氣氛中焙燒油燃料車尾氣污染物主要是CH,NO2和SOn,而b,即得Ag/V-Al2O3,PdV-Al2O3和Pt/V醇燃料車尾氣排放的主要污染物是乙醇燃燒的中Al2O3催化劑.所制得上述各類催化劑均經(jīng)壓片、間產(chǎn)物醛、OO和未燃燒的醇(尤其是在冷啟動再破碎,篩分出試樣備用時)2.至今有關(guān)乙醇燃料車尾氣凈化催化劑的研12催化劑的評價方法用固定床式石英傲型反究開發(fā)大多集中于y-A2O3負(fù)載的貴金屬(應(yīng)器評價樣品的催化性能,反應(yīng)器內(nèi)以玻璃棉撐托Pa,R)和某些過渡金屬氧化催化劑(如CuO,催化劑顆粒催化劑用量為0.1mL(約200mg),顆CO-Cn2O3,ZnO-Cr2O3等),在非貴金屬燃燒催粒徑為0.21-0.15mm反應(yīng)裝置見圖1.將空氣通化劑中,鈣鈦礦(ABO3)型稀土氧化物具有潛在的盛有乙醇的鼓泡裝置里鼓泡器置于室溫下即可,應(yīng)用前景本文在ABO2型氧化物基礎(chǔ)上引入帶有乙醇的空氣與氮氣混合,通過調(diào)整空氣和氮氣使其作為乙醇完全氧化的催化劑實驗結(jié)果顯示,的流量使反應(yīng)混合氣組成為v( H3CH3OH該催化劑對低濃度CH3CH2OH的完全氧化具有優(yōu)WO):WN)=0.3:12.5:87.3,在4800b-1的空良的催化性能,即具有低的完全起燃溫度、高的轉(zhuǎn)速下通過加熱的催化劑床層,反應(yīng)尾氣組成由氣相化率和較高的完全氧化選擇性色譜儀(GD-102,上海分析儀器廠)作在線分析1實驗部分色譜柱擔(dān)體為GDX-103;柱長3m;柱溫393K;FIT檢測器在線分析乙醇或部分還原產(chǎn)物乙1.1催化劑制備催化劑La0.6Sm.4MnO3試樣系醛先由檸檬酸為配體的溶膠一凝膠法制備其干凝膠,13催化劑的O2-TPD測試氧程序升溫脫附而后經(jīng)873K焙燒4h即得試樣,將該試樣作為基(簡稱O2-TPD,下同)測試在 Omnistar GSD3000質(zhì)浸漬計量AgNO3溶液陳放10h,而后浸漬試Ms儀上進(jìn)行,催化劑用量為20mg,測試前將前樣在空氣氣氛中973K下焙燒4h,則制得Ag修飾驅(qū)態(tài)催化劑試樣置于反應(yīng)管中,在純O2氣氛下升中國煤化工收稿日期:2003-06-1車者簡介:王偉(1963-),男,云南人,副研究員,博土,主要從事物YHCNMHG云南大學(xué)學(xué)報(自然科學(xué)版)第26卷溫至77K,而后降至室溫,經(jīng)He氣吹掃3h,然后4%Mn/Y-A2O等催化劑對乙醇的催化氧化行以20K/min速率進(jìn)行程序升溫脫附為相似2結(jié)果與討論21催化劑性能測試6%Ag/La.6Sm.4MO3催化劑和其它作為比較的4種催化劑對乙醇氧化活性實d00驗結(jié)果見表1,本文所制備的L06S04MnO基質(zhì)催化劑對低濃度乙醇完全氧化活性略優(yōu)于6%Ag/yA2O3,0.1%Py-A2O和0.1Py-AM2O3催化劑在0.1MPa,V( CH3CHOH):V(O2):V(N)=0.3:125:87.2,空速為48000h的反應(yīng)條件下,前400440480520560600者的T95溫度為506K而后三者的Ty溫度分別為523,538和573KAg的修飾使LA,6Sm04MO2基質(zhì)圖1不同溫度下各種催化荊催化氯化乙醇后尾氣中乙醛催化劑對乙醇完全氧化催化活性顯著提高在相同的體積分?jǐn)?shù)(mLm3)(a)6%Ag/La.6S04MnO3;反應(yīng)條件下6%Ag/La.6S0.4MnO3催化劑的Ts溫(b)La。6Sr.4MnO;(c)6%Ag/y-A2Oh;【d)0.1%尾氣中甲醛和的含量均在OC可檢測極限以下,說冬,PMy-A2O;(e)0.,1%P/Y-A2O度可降至453K;即使在這樣低的反應(yīng)溫度下,反應(yīng)CH,CHO content (in 10-6)in the exit-gas of ethanoloxidation at different temperatures ower the catalyst of:(a)6% Ag/Lao.s Srp, 4 MnO: (b) Lao. Sto. 4 MnO: (c)表1一些催化劑對低濃度乙醇氧化活性實驗結(jié)果6%Ag/y-A2O為;(d)0.1%PdY-A2O為;(e)0.1%Tab. I Assay results of complete oxidation activity of ethanolPt/y-AlO3in low concentration over the some catalysts催化劑Ts/KTw/K2.2催化劑的操作穩(wěn)定性能圖2為6%An.Sro.4 MnO3Ag/La0.6So4MnO3催化劑在450K反應(yīng)溫度下,6%Ag/Lao. Srp. 4MnO歷時24h操作穩(wěn)定性的考查結(jié)果考察結(jié)果顯示6% Ag/-AlO3在6%Ag/La0.Sm4MnO2催化劑上乙醇的轉(zhuǎn)化率始終保持在90%以上0.1%P/y-A2O24930. 1%Pt/y-ALO反應(yīng)條件:0.1MPa;反應(yīng)混合氣v((H3CHOH):V(O2):V(N2)=0.3:12.5:87.3;空速48000h明大多數(shù)乙醇都被催化氧化為H2O和CO2,乙醛是其部分氧化產(chǎn)物(尾氣中乙醛含量約790L/m3;但若將反應(yīng)溫度提升至493K,則幾乎100%乙醇完全氧化生成H2O和CO2,尾氣中乙醛含量能下降到1m/m3以下.而為達(dá)到如此低的尾氣中乙醛排放指標(biāo),上述另3種催化劑,圖26%Ag/IA.bSrn.4MMO3催化劑催化氧化乙醇24h穩(wěn)定性實驗6%Ag/y-Al2O3, 0. 1%Pd/y-Al203140 1 Pt,Fig 2 Stability test o ChOH oxidation for 24 h ower the catA2O3,所要求的反應(yīng)溫度要高得多(分別為593alyst of 6%Ag/Lao. 6 So.4 MnO,. Reaction oondition: 0. 1563和>623K)圖1是5種催化劑在不同溫度下產(chǎn)生乙醛體積分?jǐn)?shù)的關(guān)系曲線,隨著溫度的增加,種催化劑的曲線都出現(xiàn)一個最大值,這與文獻(xiàn)[4CNMHG圖3為2種試樣中0.1%Pt/Y-Al2O2,4%Cu-2%Cx/y-A2O3和上O2吸附的TPD譜在未經(jīng)Ag修飾的基底試樣2期王偉等:乙醇燃料車尾氣凈化催化劑研究L≈0.5 Sro anc(873K)上,吸附氧物種的TPD譜(a)接吸附在表面Ag離子上,吸附量較大并較容易呈現(xiàn)一個強(qiáng)而略顯不對稱的O2脫附峰:從673K附脫附,脫附溫度較低.由上述兩試樣的O2-TPD譜近就開始有可檢測量的氧物種的脫附,主峰峰溫位的比較可以得出結(jié)論,Ag對La06Sm.4MnO體系的于83K在約783K附近似還包含一不甚突出的肩修飾和部分摻雜取代大大提高其對O2的吸附,產(chǎn)峰在№g修飾的試樣6%Ag/L2.6Sm4MO上,相生具有低溫吸脫附性能的吸附氧物種的數(shù)量,意味應(yīng)的TPD譜(b)則出現(xiàn)2個強(qiáng)的氧物種脫附峰,峰著在反應(yīng)條件下可參與反應(yīng)的表面吸附氧以及非溫分別約為783K和883K后者與未經(jīng)Ag修飾化學(xué)計量氧數(shù)量較多這種變化趨勢與2種試樣對的試樣L。S.4MnO2上O2-TPD主峰的峰形和乙醇完全氧化催化活性的變化趨勢相一致:即Ag峰溫位置大體相同,它們很可能源于同一類氧物種修飾的體系催化乙醇完全氧化的低溫轉(zhuǎn)化活性比的脫附前者則顯然與低價金屬離子Ag+和S2+不經(jīng)Ag修飾的體系高得多在ABO型 LaMnO3晶格的摻雜和部分A-位取3結(jié)論代有關(guān),已知純Ag2O在高溫于573K的溫度下就能分解為金屬Ag和O2,通過熱重-差熱分析(TGAg對Ia.6S0.4MnO3體系的修飾和部分摻雜DTA)結(jié)果表明,純Ag2O失重峰出現(xiàn)在623~取代大大提高其對O2的吸附,增加了催化劑表面753K,并伴隨出現(xiàn)一吸熱峰;而經(jīng)773K熱處理過活性氧物種的數(shù)量,使得6%Ag/I-a06Sm04MnO的Ag2O試樣在從室溫至1073K升溫過程中,未催化劑較La6 Sro, 4 MnO2催化劑對乙醇的完全氧觀察到任何失重峰XPS結(jié)果5則已表明,在經(jīng)化有更高的催化活性,這種催化劑具有低成本、高773K焙燒制備的Ag/l40.Sm.4MnO3表面仍保留催化活性的特點有望成為乙醇汽油車尾氣凈化催著一類不能熱分解為金屬Ag和O2的Ag2O物種.化轉(zhuǎn)化器的催化活性涂層于是我們認(rèn)為,在73處強(qiáng)的O2-TPD峰系源參考文獻(xiàn):于另一類弱吸附氧物種的脫附,而非Ag2O組分的熱分解峰這另一類氧物種或是處于Ag在A位11 MACDOUGALL L V Methanol to fuels routes-the的部分摻雜取代而誘生出的陰離子缺位上,或是直achievements and remaining problems[J]. Catal Today,1991,(8):337-369[2] MCCABE R W, MITCHELL P J. Exhaust-catalyst de-elopment for methanol-fueled Vehicles 1 A comparatistudy of methand oxidation over alumina-supported catalysts cuntaining group 8, 10, and 11 metals[J]. Appl[3] PLUMMER H K, WATKINS J W LH GANDHI SCharacterization of silver catalysts for the axidation of[4 MCCABE R W. MITCHELL P J Reaction of ethanol47357367387397310731173nd acetaldehyde over noble metal and metal oxide catalysts Ind Eng[J]. Cherm Prod Res DC, 1984, 23(2):(a)La. Sro. 4 MnO (b)6%Ag/la. Sro, MnO,圖3不同催化劑的O2-TP圖[5]王偉張鴻斌Ag/ LaStInG3催化劑表面的XPS研Fig 3 -TPD spectra of different catalysts究[A]第十屆全國催化學(xué)術(shù)會議論文集[C].太原版社,2000中國煤化工CNMHG轉(zhuǎn)第167頁第2期李祖強(qiáng)等:尖萼金絲桃中間苯三酚及黃酮類成分167Phloroglucinol and flavonoid constituents of Hypericum acmosepaiunLI Zu-giang', LUO Lei, MA Guo-yi, CHEN(1. Experimental Center of Yunnan University, Kunming 650091, China;2. Chemical Engineering College of Yunnan Normal University, Kunming 650091, China3. Faculty of Pharmacy, the University of Sydney, NSW, Australia)Abstract: Cytotoxicity screening of extracts of Hypericum acmosepaium N. Robson were carL1zto cell and KB cell. Isolation of chemical constituents as carried out from the effective parts of H. acmosepium by column chromatography. The chemical structures as identified by physical and chemical constants andpectral data analysis Six compounds have been isolated and their structures have been established as paglucinol (1): 5-hydroxy -6-isobutyryl-2, 2, 8-trimethyl-8-(3'-methylbut-2"-enyl)-2, 8-dihydro1-benzopyran-7-one(2); 5-hydroxy-6-propionyl-2, 2, 8-trimethyl-8-(3-methylbut-2eny)-2,8- dihydro-1- benzopyran-7-one(3);78-(2”,2”- dimethylpyrano)-5,3’,4’- tinyroxy-3-methoxylflavone(4); quercetin(5)and I 3, II8-biapigenin(6). In addition, the fractions ofdichloromethane extraction, ethyl acetate extraction, compounds 2 and 5 possess cytotoxic activitiesKey words: Hypericum acmosepaium N. Robson; phloroglucinol; flavonoid; cytotoxicity并善蕭并并并“并美類并并并“餐#美并莠(上接第161頁)Study of catalysts for complete oxidation of alcohol fueled car exhaustsWANG Wei, TU Xue-yan, ZHANG Shi-hong(The Facuilty of Chermical and Materials Engineering, Yunnan University, Kunming 650091, China)Abstract: A highly active Ag-modified Lao, 6 Sro. 4 MnO catalyst with the perovskite-type structure hasbeen designed and prepared. It is observed experimentally that this catalyst exhibits the activity significantlyhigher than that of supported precious metal catalysts O2-TPD shows that modification of Ag to the surfaceof Iag. Sro MnO catalyst increases the relative content of the surface 02/0" species on surface, which arehighly reactive toward alcohoKey words: complete catalysts oxidation; exhausts; alcohol; catalysts中國煤化工CNMHG