焙烧温度对甲烷催化部分氧化Ni/MgO-Al2O3催化剂结构和性能的影响

采用TPR、BET、XRD、TG及反应性能评价等研究方法，考察了焙烧温度对甲烷催化部分氧化制合成气Ni/MgO-Al2O3催化剂结构和性能的影响。研究结果表明，随焙烧温度的升高， Ni/MgO-Al2O3中的镍物种与载体作用逐渐增强，生成了NiAl2O4尖晶石和NiMgO2固熔体。虽然焙烧温度提高会使催化剂比表面降低，由于尖晶石结构的形成，其热稳定性会明显提高，将有利于抑制催化剂在反应过程中因烧结而失活的可能性。与低温焙烧的催化剂相比，高温焙烧的催化剂仍表现出良好催化反应性能，并具有相对较好的稳定性。高温焙烧的催化剂在反应过程中床层的热点温度相对较低，热点温度波动幅度也较小。低温和高温焙烧的Ni/MgO-Al2O3催化剂在常压、1 083 K、CH4与O2摩尔比为1.8、空速2.66×105 h－1的反应条件下均具有良好的抗积炭性能。

Effects of calcinations temperature on structure and catalytic performance of Ni/MgO- Al2O3 catalysts for partial oxidation of methane

The effects of calcination temperature on the properties of Ni/MgO-Al2O3 were studied by the means of XRD, TPR, BET，TG and catalytic performance evaluation. With the increase of calcination temperature of the catalysts, the interaction between nickel species and support became stronger, and NiAl2O4, MgAl2O4 spinel and NiMgO2 formed. Compared withγ-alumina, the Ni/MgO-Al2O3 catalysts showed larger specific surface area even at higher calcination temperature due to the formation of spinel. In the partial oxidation of methane to syngas, the Ni/MgO-Al2O3 catalysts calcinated at higher temperature exhibited better stability under the conditions of atmospheric pressure, 1 083 K, CH4/O2=1.8 and 2.66×105 h－1. Whether Ni/MgO-Al2O3 catalysts were calcined at low or high temperature, they all showed higher resistance to coking. In addition, the hotspot temperature of the catalytic bed for the catalysts calcinated at high temperature decreased, which benefits to prevent the catalysts from sintering.