Mg/Al比对CH4-CO2重整制合成气Mg（Ni,Al）O复合氧化物催化剂性能的影响

Effect of Mg/Al ratio on catalytic performance of Mg（Ni,Al）O composite oxide catalyst for CH4-CO2 reforming

通过焙烧由共沉淀法制备的类水滑石化合物(HTLcs)前驱体,制备了一系列不同n(Mg)/n(Al)比(0.5,1,2和3)的Mg(Ni,Al)O复合氧化物催化剂。将该催化剂用于甲烷二氧化碳重整反应(CRM)中,并考查了Mg/Al比对催化剂活性的影响。借助XRD,BET,H2-TPR,CO2-TPD以及O2-TPO等表征手段研究催化剂结构和催化性能之间的关系。结果表明催化剂的催化活性和抗积炭性能与Mg/Al比有关。高Mg/Al比的催化剂表现出较好的催化活性和抗积炭性能,而当n(Mg)/n(Al)=1时催化剂的催化的活性和稳定性最佳,且催化剂表面生成的积炭量最少。MgAl2O4和MgO共存使催化剂具有强的金属与载体作用力,适当的CO2吸附能力,这导致催化剂具有较好的催化活性和较强的抗积炭能力。

Mg(Ni,Al)O composite oxide catalysts with different Mg/Al molar ratios(0.5,1,2 and 3)were obviously affected by crystal size.The nano-sized ZSM-5 zeolite exhibited excellent catalytic activity due to its large external surface area,short diffuse path length and good acid site accessibility.The optimal reaction conditions for the nano ZSM-5 zeolite were determined by experiments as follows:0-0.1MPa,360-380℃,and feed rate of 300-400mL/h.prepared by calcining the hydrotalcite-like compounds(HTLcs)precursors obtained by co-precipitation.The obtained catalysts were used in the CO2 reforming of CH4(CRM)and the effect of Mg/Al ratios on the catalytic performance was investigated.XRD,N2 adsorption-desorption,H2-TPR,CO2-TPD and O2-TPO-MS techniques were employed to elucidate the relationship between structure and catalytic performance.The results showed that the catalytic activity and and anti coking performance of the catalysts strongly relied on the Mg/Al ratio.The catalysts with higher Mg/Al ratios exhibited better catalytic activity and coke resistance,and the catalyst with the Mg/Al molar ratio of 1 had the best catalytic activity and stability,and the amount of carbon deposition on the catalyst surface was the least.The coexistence of MgAl2O4 and MgO endows the catalyst with strong metal-support interaction and proper CO2 adsorption capacity,which results in better catalytic activity and strong carbon deposition resistance.