Aqueous-phase reforming of bio-oil aqueous fraction over nickel-based catalysts

Aqueous-phase reforming (APR) is a quite new technology for the production of hydrogen and light hydrocarbons from aqueous-organic mixtures in a single-stage process. This manuscript analyzes the APR of representative model compounds of bio-oil aqueous fraction, including acetic acid, ethanol, 1-hydroxypropan-2-one (acetol) and benzene-1,2-diol (catechol), as well as a mixture of all of them. The APR experiments were conducted at 230 °C and 3.2 MPa over three different Ni-based catalysts, including spinel NiAl2O4, and supported Ni/CeO2-γAl2O3 and Ni/La2O3-αAl2O3. The reactivity of the model compounds varied largely in the order: acetol > ethanol > catechol > acetic acid, whereas the H2 production decreased in the following order: ethanol ≫> acetol > acetic acid > catechol. Based on the product distribution obtained, the reaction pathways in the APR of each model compound have been proposed. In the APR of the mixture, the Ni/La2O3-αAl2O3 led to the highest H2 yield but was affected by Ni leaching, whereas spinel NiAl2O4 showed a much higher stability. Therefore, the Ni-spinel catalyst showed a good potential for H2 production by APR of bio-oil aqueous fraction.