Investigation on Co–Modified Ni_xMg_yO Solid Solutions for Hydrogen Production from Steam Reforming of Acetic Acid and a Model Blend

This paper is focused on the Co-modified Ni_xMg_yO solid solutions (10 wt% Ni, 2–6 wt% Co) for the steam reforming of acetic acid and a model blend. The pristine rocksalt structured Ni_xMg_yO solid solution and the modified Ni_xMg_yO−Co catalysts were synthesized via hydrothermal method and co-impregnation. The activity of the catalysts was evaluated in the temperature range of 500–800 °C with a steam/carbon molar ratio of 3 and a gas hourly space velocity (GHSV) of 57,000 h⁻¹. Low cobalt content (Co loading = 2 wt%) catalysts exhibited significant promotion of H₂ yield via enhancement of both water-gas shift (WGS) reaction and methane decomposition. A 30-hour test at 700 °C achieved excellent acetic acid conversion rate and H₂ yield of 99.1% and 86.9%, respectively. However, the catalysts with higher cobalt loading (Co loading ≥ 4 wt%) suffered a much quicker deactivation mainly due to carbon deposition. In addition, the catalysts were also tested on a model blend combined acids, alcohols and aromatic species and exhibited outstanding performance with carbon conversion above 90% and H₂ yield above 70% for 100 h.