Auto-thermal reforming of acetic acid over hydrotalcites-derived co-based catalyst: A stable and anti-coking Co/Sr-Alx-O catalyst

Hydrogen, as a clean energy carrier, can be extracted from acetic acid (HAc) via bio-oil. Auto-thermal reforming (ATR) of HAc using non-noble metal catalysts has been studied as an attractive option to produce hydrogen. However, the poor catalytic stability and coking over these non-noble metal catalysts are still problems. In this work, a series of Co/Sr-Alx-O catalysts with different Sr/Al molar ratios (x = 0, 1/12, 1/6, 1/2, 2) were prepared from hydrotalcite precursors, and fine Co particles was highly dispersed on the Sr(Al)O mixed oxide obtained from the hydrotalcite. The Co/Sr-Al1/6-O produced a high activity and enhanced stability: the conversion of HAc reached 100% and the H2 yield remained stable near 2.6 mol-H2/mol-HAc with a reaction rate and turnover frequency (TOF) at 17.04 mmol-HAc.s−1.gcat−1 and 0.19 s−1, respectively, which are much higher than either Co/SrO (2.51 mmol-HAc.s−1.gcat −1 and 0.011 s−1) or Co/Sr-Al2-O (3.86 mmol-HAc.s−1.gcat −1 and 0.067 s−1). No obvious coking was found. This improved reactivity can be due to 1) the high dispersion of Co metal and 2) interaction with support of Sr(Al)O mixed oxide, where the fine cobalt particles brought about more active sites and the Sr(Al)O promoted gasification of coking and inhibited the separation of Co metal from support.