Ni-based catalysts supported on MgAl2O4 with different properties for combined steam and CO2 reforming of methane

Abstract

Three MgAl2O4 spinels were prepared by co-precipitation (cp), sol–gel (sg) and alcoholysis (al) methods, and used as supports for Ni catalysts for combined steam and CO2 reforming of methane (CSCRM). MgAl2O4(cp), MgAl2O4(sg) and MgAl2O4(al) showed different textural, morphological and chemical properties. By comparison of the properties of MgAl2O4 with those of 10Ni/MgAl2O4 (10 wt% Ni loading), it was found that the basicity of MgAl2O4 was a major factor influencing not only the basicity of catalyst but also the Ni particle size and dispersion. MgAl2O4(sg) possessed the highest amount of basic sites leading to 10Ni/MgAl2O4(sg) having the strongest basicity and the smallest Ni particle size. These properties bestowed 10Ni/MgAl2O4(sg) with superior anti-coking and anti-sintering properties as well as the highest activity and stability for CSCRM among all catalysts including 10Ni/MgO and 10Ni/γ-Al2O3. Further investigations on the effect of Ni loading (5–15 wt%) showed that 10Ni/MgAl2O4(sg) was the best catalyst for CSCRM, with stable conversions of CH4 (88.9%) and CO2 (68.6%) over 30 h on stream (CH4:H2O:CO2 = 2.5:2:1 (molar ratio)) at 800 °C, 0.1 MPa and a gas hourly space velocity of 132,000 NmL/(gcat·h).