Alcohol‐Mediated Photocatalytic Ring‐Hydrogenation of Furfuryl Alcohol Over Rh/TiO 2
Atsuya Inagaki, Atsuhiro Tanaka, Hiroshi KominamiABSTRACT
Ring‐hydrogenation of furfuryl alcohol (FOL) to tetrahydrofurfuryl alcohol (THFA) is important due to its wide application; but still challenge because side reaction of FOL such as hydrogenolysis of the hydroxymethyl (HM) group often occurs and reduces the THFA selectivity. In this study, various metal‐loaded titanium(IV) oxide (M/TiO 2 ) photocatalysts were prepared by using a photodeposition method and then used for photocatalytic hydrogenation of FOL in alcoholic suspensions of M/TiO 2 , in which hydrogen transfer from alcohol to FOL occurs, making the hydrogenation possible without the use of hydrogen (H 2 ) gas. Among M/TiO 2 photocatalysts, only TiO 2 loaded with rhodium (Rh/TiO 2 ) and palladium (Pd/TiO 2 ) exhibited the reactivity to FOL; however, the catalytic performance was different each other. Rh/TiO 2 photocatalyst exhibited a high selectivity toward the C═C bond, even with repeated use, and negligible selectivity toward the HM group of FOL, resulting in a high yield of THFA. On the other hand, Pd/TiO 2 photocatalyst also showed the reactivity for hydrogenolysis of the HM group of FOL, largely decreasing the THFA yield. These catalytic properties of Rh/TiO 2 and Pd/TiO 2 were enlarged at higher reaction temperatures and further confirmed in the hydrogenolysis of the HM group of benzyl alcohol (BAL), in which no ring‐hydrogenation occurred over both photocatalysts.