Preparation of a Ni-MgO-Al₂O₃ catalyst with high activity and resistance to potassium poisoning during direct internal reforming of methane in molten carbonate fuel cells

Steam reforming of methane (SRM) is conducted using a series of Ni-MgO-Al₂O₃ catalysts for direct internal reforming (DIR) in molten carbonate fuel cells (MCFCs). Ni-MgO-Al₂O₃ catalysts are prepared by the homogeneous precipitation method with a variety of MgO loading amounts ranging from 3 to 15 wt%. In addition, each precursor concentrations are systemically changed (Ni: 1.2–4.8 mol L⁻¹; Mg: 0.3–1.2 mol L⁻¹; Al: 0.4–1.6 mol L⁻¹) at the optimized composition (10 wt% MgO). The effects of MgO loading and precursor concentration on the catalytic performance and resistance against poisoning of the catalyst by potassium (K) are investigated. The Ni-MgO-Al₂O₃ catalyst with 10 wt% MgO and the original precursor concentration (Ni: 1.2 mol L⁻¹; Mg: 0.3 mol L⁻¹; Al: 0.4 mol L⁻¹) exhibits the highest CH₄ conversion and resistance against K poisoning even at the extremely high gas space velocity (GHSV) of 1,512,000 h⁻¹. Excellent SRM performance of the Ni-MgO-Al₂O₃ catalyst is attributed to strong metal (Ni) to alumina support interaction (SMSI) when magnesium oxide (MgO) is co-precipitated with the Ni-Al₂O₃. The enhanced interaction of the Ni with MgO-Al₂O₃ support is found to protect the active Ni species against K poisoning.