Selective hydrogenation of acetophenone to 1-phenylethanol on Pt/ TiO2 catalysts prepared by pulsed dc magnetron sputtering

Abstract

1-Phenylethanol (PHE) is a high-value chemical with various applications in fragrance and pharmaceutical industries. It is extensively used as strawberry fragrance additives in yogurts and chewing gums and an intermediate of anti-inflammatory drugs such as Ibuprofen. In this study, selective hydrogenation of acetophenone (AP) to PHE was investigated using platinum catalysts supported on different types of titanium dioxide including PC500 (pure anatase) and P25 (anatase mixed rutile). Pt was deposited on the titanium dioxide supports by pulsed direct current magnetron sputtering (PDC-MSD) method with deposition time spent on Pt coating at 3, 6, and 9 minutes. For comparison purposes, Pt/TiO2 catalysts were also prepared by incipient wetness impregnation method with similar Pt loadings (%). The characteristics and catalyst properties were analyzed by XRD, N2-physisorption, XPS, ICP-OES, TEM, CO-chemisorption, and H2-TPR. Hydrogenation of AP was carried out in a batch reactor at the pressure of 1 bar H2 and the temperature of 80oC for 2 hours using 2-propanol as the solvent. It was found that increasing sputtering time resulted in a larger average Pt particle size deposited on the TiO2 surface and increased amount of Pt loading (%). For any sputtering time used, platinum catalysts on PC500 TiO2 support provided higher selectivity of PHE than on P25 because of higher atomic ratio of Pt/Ti on the catalyst surfaces and higher Pt dispersion (%) on the PC500 TiO2 surface. However, increasing Pt loading (%) may also catalyze the hydrogenolysis of PHE to ethylbenzene (EB), resulting in lower PHE product. Moreover, at the reaction temperature of 80 oC could promote the hydrogenation of AP to PHE and inhibit hydrogenolysis of PHE to EB in 2-propanol solvent.