Auto-thermal reforming (ATR) is an effective route to extract hydrogen from acetic acid (HAc) derived from biomass. However, carbon deposition and sintering of cobalt metal are main concerns which lead...

Autothermal reforming (ATR) is an effective route for hydrogen production from acetic acid (HAc) derived from biomass. Ni-based catalysts are promising candidates for ATR due to their high activity, but coke formation hinders their practical application. To tackle this issue, a series of Ni-Mg-Cr catalysts with supports of Cr 2 O 3 or MgCr 2 O 4 were prepared by the sol−gel method and evaluated in ATR. The results indicated that as compared to the Ni-Cr 2 O 3 catalyst, the Ni 0.25 Mg 0.75 CrO 3.5±δ catalyst with MgCr 2 O 4 support presented higher catalytic performance: the conversion rate of acetic acid was stable near 100%, with hydrogen yield reaching 2.64 mol-H 2 /mol-HAc during a 40 h ATR test, while there was no obvious coking. It was found that Mg modification was prone to constituting a stable MgCr 2 O 4 spinel support with a high specific surface area for adsorption and transformation of HAc; however, for catalysts with excessive Mg addition, namely, Ni 0.43 Mg 2.56 CrO 4.5±δ and Ni 0.69 Mg 5.31 CrO 7.5±δ , low reactivity was found and was linked to constraining of Ni from the solid solution of Mg(Ni)O. Density functional theory (DFT) calculations reveal that during the ATR process, Ni 4 -MgCr 2 O 4 presents a low energy barrier for the overall transformation path and a high stabilization of reaction intermediates; furthermore, as compared to Ni 4 -Cr 2 O 3 , oxidation of C* species by O* and OH* is significantly accelerated on Ni 4 -MgCr 2 O 4 due to the considerably decreased energy barriers, thus eliminating carbon deposition and improving catalytic activity.

To obtain high yields of hydrogen, a series of Zr x Pr 1-x O y -supported cobalt catalysts were synthesized by the sol-gel method and tested in autothermal reforming (ATR) of acetic acid (HAc) derived from bio-oil. X-ray diffraction, nitrogen physisorption, H 2 -temperature-programmed reduction, and thermogravimetric analysis were conducted to investigate the factors affecting the activities of the catalysts. Over the Co-Zr-Pr-O catalyst, a Zr x Pr 1-x O y solid solution was formed after calcination; meanwhile, the active component of Co 0 was highly dispersed over the solid solution after reduction in hydrogen for 1 h at 700 °C. As a result, stable reactivity was recorded in the ATR process of HAc: the hydrogen yield reached 2.58 mol H2 mol À1HAc with near 100 % HAc conversion, while better resistance to coking was observed.