TiO2-supported Ni-Sn as an effective hydrogenation catalyst for aqueous acetic acid to ethanol

• Published in: Energy reports 2020-11, Vol.6, p.2249-2255
• Main Authors: Zhao, Yuanyuan, Nishida, Takayuki, Minami, Eiji, Saka, Shiro, Kawamoto, Haruo
• Format: Article
• Language: English
• Subjects: Acetic acid; Bioethanol; Hydrogenation; Ni-Sn/TiO2
• ISSN: 2352-4847; 2352-4847
• DOI: 10.1016/j.egyr.2020.08.007

Various Ni and Ni-Sn catalysts supported on TiO2 were prepared and the catalytic activities were evaluated for ethanol formation from aqueous acetic acid. Although catalytic activities of the Ni/TiO2 catalysts were limited, the addition of Sn improved the activity dramatically, and the optimum Ni/Sn ratio was approximately 1:1 (w/w). SnO2, the precursor of Sn, could not be reduced into metal Sn in pure form but did reduce into Ni-Sn alloys in the presence of NiO, the precursor of Ni. Analyses with XRD and SEM-EDS revealed that the Ni-Sn alloys were homogeneously dispersed on the TiO2 surface. Furthermore, IR analysis indicated that the Ti atoms in the catalyst act as a Lewis acid, which coordinates to the oxygen atoms of acetic acid, enhancing the attack of hydrogens activated on neighboring Ni-Sn alloys. Based on these results, Ni-Sn/TiO2 is proposed as an effective hydrogenation catalyst for converting aqueous acetic acid into ethanol. [Display omitted] •Ni-Sn/TiO2 catalyst is highly active for aqueous acetic acid hydrogenation.•The addition of Sn dramatically increases hydrogenation activity of Ni/TiO2 catalyst.•Ni-Sn alloy is hydrogen activation site of Ni-Sn/TiO2 catalyst.•SnO2 is reduced at lower temperatures in the presence of Ni metal.•Ti atoms of TiO2 support acts as a Lewis acid site to promote acetic acid hydrogenation.