Ni-CeO_2/Al_2O_3催化剂的制备、表征及其生物质合成气甲烷化性能研究

Preparation and Characterization of Ni-CeO_2/Al_2O_3 and Its Catalytic Performance for Methanation of Biomass Syngas

采用共浸渍法制备了添加不同助剂(CeO_2、ZrO_2、Co_3O_4、Y_2O_3、V_2O_5)的一系列Ni基催化剂,采用XRD、SEM、BET、H_2-TPR等对催化剂的结构进行表征,对Ni含量、助剂含量、浸渍顺序、焙烧温度、还原温度、空速等条件进行优化,并考察了催化剂的生物质合成气甲烷化性能。结果表明:助剂CeO_2、ZrO2、Y_2O_3、V_2O_5的加入均能提高催化剂对CO甲烷化的催化活性,其中6Ni-3CeO_2/Al_2O_3的催化活性、稳定性和抗积碳能力最好;采用6Ni-3CeO_2/Al_2O_3催化剂,在V(H_2)∶V(CO)∶V(N_2)=0.45∶0.15∶0.40、空速为20 000h-1、常压、350℃下,CO即可完全转化,甲烷选择性达到90%,较6Ni/Al_2O_3催化剂提高了16%,CO完全转化温度较6Ni/Al_2O_3催化剂低50℃。6Ni-3CeO_2/Al_2O_3催化剂的Ni含量明显低于文献报道,应用于生物质合成气催化加氢转化为甲烷,CO转化率达到80.5%,有效地解决了生物质合成气中CO含量高于民用燃气标准的问题。

A series of Ni-based catalysts with addition of different additives（CeO2,ZrO2,Co3O4,Y2O3,V2O5）were prepared by a co-impregnation method.The structure of the catalysts was characterized by XRD,SEM,BET,H2-TPR,etc.Effects of Ni content,additive content,impregnation order,calcination temperature,reduction temperature and space velocity（SV）on the catalytic activity were investigated.The catalytic performance for methanation of biomass syngas was evaluated.Results showed that,adding CeO2,ZrO2,Y2O3,V2O5 could improve the catalytic activity for methanation of CO,and the catalyst 6Ni-3CeO2/Al2O3 had the highest catalytic activity,the best stability and the best coke resistance.Using 6Ni-3CeO2/Al2O3 as a catalyst,CO could be completely converted at conditions as follows：V（H2）∶V（CO）∶V（N2）=0.45∶0.15∶0.40,SV=20 000h^-1,atmosphere pressure,350 ℃,CH4 selectivity reached 90%,which increased by 16% than that of catalyst 6Ni/Al2O3,the temperature of CO completely conversion was 50℃lower than that of catalyst 6Ni/Al2O3.The Ni content of catalyst 6Ni-3CeO2/Al2O3 was obviously lower than that of reported in literature.The catalystwas applied to methanation of biomass syngas by catalytic hydrogenation with CO conversion rate of 80.5%,and the problem ＂CO content in biomass syngas is higher than civil gas standard＂was effectively solved.