Effects of Re addition upon aqueous phase reforming of ethanol over TiO2 supported Rh and Ir catalysts

• Published in: International journal of hydrogen energy 2015-03, Vol.40 (11), p.4129-4140
• Main Authors: Nozawa, Toshiaki, Yoshida, Akihiro, Hikichi, Shiro, Naito, Shuichi
• Format: Article
• Language: English
• Subjects: Aqueous phase reforming of ethanol; Iridium; Rhenium; Rhodium; Titanium dioxide
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2015.01.152

Effect of addition of rhenium was investigated during catalysis of TiO2-supported Rh and Ir metals for aqueous phase reforming of ethanol. By adding Re to Rh/TiO2 and Ir/TiO2 catalysts, the initial rates of H2, CH4, and CO2 formation increased 3–4 times, together with the extraordinary increase of acetic acid formation. Detailed mechanisms of the reforming reaction were investigated using various physicochemical techniques. The role of added Re was the acceleration of the hydration of acetaldehyde to form acetic acid rather than the decomposition of acetaldehyde to form CH4 and CO on both Rh/TiO2 and Ir/TiO2 catalysts. Well dispersed bimetallic nano-composites would work as the active sites for ethanol dehydrogenation and acetaldehyde decomposition, whereas partially oxidized ReOx sites may work for the hydration of acetaldehyde to form acetic acid. [Display omitted] •EtOH-APR over Rh/TiO2 and Ir/TiO2 are accelerated by Re addition.•H2 selectivity is controlled by AcH decomposition (path I) and hydration (path II).•Rh–Re and Ir–Re nano-composites accelerate EtOH dehydrogenation to AcH.•Highly dispersed ReOx species are active for hydration of AcH to AcOH.