Promoted Ni Catalyst Over Titania-Zirconia Support for Partial Oxidation of Methane: Simple and Practical Catalysts

Methane is a highly potent greenhouse gas, and its mitigation is deliberately needed. The partial oxidation of methane (POM) is a promising route for depleting methane with a high H₂/CO ratio through direct and indirect reaction pathways. In this study, the catalyst Ni stabilized over titania-zirconia support is found to retain the catalytic active sites exposed for a constant 30% H₂ yield with an H₂/CO ratio of 4.25 up to 300 h. Furthermore, the promotion role of 2wt% Cs, Ce, Sr over Ni/TiZr catalyst is studied for POM reaction where 2wt% Cs addition to Ni/TiZr is found to be decremental toward POM due to the lowest density of basic sites. 2wt% Sr promoted Ni/TiZr performs best due to the highest edge of reducibility, the highest population of active sites, and retention of active sites in a reduced state against O₂ during POM reaction. It ensures > 45% CH₄ conversion, > 40% H₂ yield, and 3.7 H₂/CO ratio at 600 °C during the 300-min time on stream. At high reaction temperature (750 °C) over NiSr/TiZr catalyst, the H₂/CO ratio is dropped to ~ 2 and the H₂ yield is jumped to 97% indicating the exclusive presence of a direct pathway for POM.