Pd/Ce/γ-Al2O3和Pd/Ce-La/γ-Al2O3甲醇低溫裂解催化劑

第21卷第1期催化學(xué)報2000年1月Vol. 21 No. 1Chinese Journal of CatalysisJanuary 2000Article Il:0253983X20001000502Decomposition of Methanol over Pd/ce/y-Al2O3 andPd/Ce-La/y-AL2O3 CatalystsYANG Cheng, CHEN Xiaoping, WANG Xiuzhi REN Jie, SUN YuharThe Chinese academy of Sciences Taiyuan 030001, ChinaKey words: methanol decomposition palladium alumina rare earth oxide supported catalyst, stabilityCLC number: 0643Document code: AMethanol is an alternative fuel for automobiles the reaction are analyzed with gas chromatographin the future. Decomposition of methanol by on-The effect of pd content on methanol decomboard reforming into H, and CO as the feed for the position over Pd/Ce/y-Al2O3 is shown in Fig 1engine has received increasing attention owing to The methanol conversion was maximum( ca 95%)energy saving and environmentally benign aimf 21. with 87% of CO selectivity when Pd loading wasTo meet the requirements of the process, new cata- 3%. In addition, dimethyl ether( DME was thelysts with high activity at low temperatures are in- main by-product. Apparently there appeared ardispensable. Several catalytic systems have been e-valuated for methanol decomposition but high reaction temperature and side reactions were alwaysoroblems 31. Recently supported noble metal cata885lysts have been considered as the alternative formethanol decomposition[ 4 5]. In this work, a newpalladium catalyst with rare earth metal oxide(CeO, La,O3)coated y-Al,O, as the supports wasdeveloped. The supports were prepared by coatingPd)/%y-AlO with ceric nitrate and/or lanthanum niFig 1 Effect of Pd loading on methanol decompositiontrate. Palladium catalysts were prepared byover Pd/Ce/y-AlO3(1)XO MeOH), (2)SOO)ating coated y-Al,O3 with PdCl, solution. CatalytMHSV=1.8h1,T=523K,(CeO2)=35%ic tests were performed in a stainless fixed-bed conoptimal proportion between Pd content and CeOtinuous flow reactor (6 mm ) The effluents ofTable 1 Methanol decomposition over Pd/Ce-La/y-AlO at different temperaturesSelectivity(%)X( MeOH y%V(H,yVCO)DE×247334.998,798.7中國煤化工CNMHG98.9(P)=3.0%,a(CO2)=22%,x(La2O3)=10%,MHsV=1.8h1Received date: 1999-08-20. First author: YANG Cheng male born in 1974, PhD studentCorrespondingauthor:SUNYuhan.Tel:(0351)130327;Fax:03510050320;E-mailsklec@public.tysx.cnFoundat序數據 upported by the Youth Foundation of Shanxi Province(991010)6催化學(xué)報第21卷loading indicating a synergetic effect between palladium and ceria for methanol decompositionTable 1 shows methanol conversion and product selectivity of methanol decomposition over Pd/Ce-La/y-AL,O3. Methanol was mainly decomposedto CO and H2. Only a small amount of CH4 andCO was produced with total selectivity less than1. 5%. Pd/Ce-La/y-AL,O3 showed lower activit010203040506070809010than Pd/Ce/y-Al,O, but the formation of DMEwas not observed over Pd/Ce-La/y-AlO3. ThoughFig 2 Stability of Pd/Ce/y-AL,O catalyDME is also a kind of clean fuel it is not favorableT=523 K, MHSV=1.8 h- Ito improve the combustion value of the fuel. DMEReferencesis produced by methanol dehydration reactionI Yoon H, Stouffer M R, Dudt PJ et al. Energy progi(2CH3OH→ CHSOCH3+H2O)1985,52):78In brief supported Pd catalyst was developed 2 Mizuno K. Hwomen 1981, 1%9): 513or methanol decomposi- 3 Pena M A, Gomez J P, Fierro J L G. Appl Catal Ation as well as higher selectivity for CO and H, than1996,141/2):7other known catalysts. This catalyst with low tem- 4 Matsumura Y, Okumura M, Usami Y et al. Catal lettperature high activity can satisty the needs of on-1997,443/4):189board reforming. The stability test for the catalyst5 Matsumura Y, Kagawa K, Usami Y et al. Chem Commn( Cambridge),1997,(7):657C see Fig 2) indicated that the activity of Pd/ce/yAlO, did not decrease after 100 h. Furthermore(Ed WGZh)the catalyst showed favorable flexibility underous conditions when it was performed for simulatingthe motor running for 450 h中國煤化工CNMHG