A review of catalytic aqueous-phase reforming of oxygenated hydrocarbons derived from biorefinery water fractions

Aqueous-phase reforming (APR) of oxygenated hydrocarbons is a process for the production of hydrogen and light alkanes. The reactants of APR remain in liquid phase during the reaction avoiding an energetically demanding vaporization-step compared to processes such as steam reforming (SR). Furthermore, low reaction temperatures thermodynamically favour the formation of hydrogen with low carbon monoxide content. Therefore, APR has been recently considered as a promising route to upgrade organic compounds found in biorefinery water fractions.Aqueous oxygenated hydrocarbons are reformed at low temperatures (200-250 °C) and high pressures (15-50 bar), typically with platinum- and nickel-based catalyst. In addition, metal combinations of these and other metals have been applied to enhance the catalyst performance. Alumina has been extensively used as catalyst support in APR. Nonetheless, other oxides and carbonaceous materials have been applied to improve the stability of catalysts.Hydrothermal conditions and high pressure present operational challenges that hinder the development of aqueous-phase reforming. However, low yields of desired products and fast catalyst deactivation constitute the main barriers. To maximize the APR effectiveness, the optimization of operation conditions and more active and durable catalysts are required.