助剂对Ni/Co双金属催化剂上沼气重整制氢的影响

Effects of additives on biogas reforming to hydrogen over NiCo bimetallic catalyst

用传统的等体积浸渍法制备了不同助剂掺杂的NiCo/γ-Al2O3双金属催化剂,用V(CH4)/V(CO2)=1的混合气体模拟沼气,考察了助剂对沼气重整制氢催化剂NiCo/γ-Al2O3的催化性能与结构的影响。运用X射线衍射(XRD)、H2程序升温还原(H2-TPR)、BET比表面积与孔结构分析(BET)、热重-差示扫描量热(TG-DSC)、程序升温加氢(TPH)等手段对催化剂进行了表征。结果表明,NiCo/γ-Al2O3催化剂掺杂La2O3、CeO2或CaO后活性较好。CeO2在反应前后发生了晶型转变,ZrO2反应后仍以晶体形式存在,其它助剂以无定形均匀地分散在载体中。除ZrO2外的助剂增强了载体与金属之间的相互作用,使催化剂难以被还原。助剂的添加使催化剂的比表面积、孔容都有所减少,却明显改善了催化剂的抗积炭性能,其中La2O3与CeO2是较好的助剂。

NiCo/γ-Al2O3 bimetallic catalysts doped with different additives were prepared by conventional incipient wetness impregnation.The experimental biogas was simulated with a gas composed of equal volumes of CH4 and CO2.Effects of additives on the performance and physicochemical properties of NiCo/γ-Al2O3 catalyst were investigated.The catalysts were characterized by XRD,H2-TPR,BET,TG-DSC and TPH.Results showed that doped La2O3,CeO2 or CaO improved the activity of NiCo/γ-Al2O3 catalyst.Crystal CeO2 was changed into amorphous after reaction,but crystal ZrO2 did not change.Other additives dispersed evenly in support by the amorphous form.All additives but ZrO2 enhanced the interaction between metal and support,which made the catalysts more difficult to be reduced.The addition of additives decreased the BET specific surface area and pore volume of the catalysts,but improved obviously anti-coking performance.La2O3 and CeO2 were better additives.