Hydrogenation of styrene oxide in the presence of supported platinum catalysts to produce 2-phenylethanol

Abstract

Gas-phase hydrogenation of styrene oxide was investigated using platinum catalysts deposited on magnesia, γ-alumina and activated carbon (AC), at atmospheric pressure and within a wide range of temperature (348–398 K). In order to correlate the chemical and textural properties with the catalytic activity, all catalysts were characterized by several techniques such as X-ray diffraction (XRD), temperature-programmed reduction (TPR), H 2-temperature-programmed desorption (TPD) N 2 physisorption and H 2 chemisorption. Obtained results indicate that the catalytic activity and the selectivity were affected by the nature of the support. In the presence of MgO or activated carbon, as supports, the main product was 2-phenylethanol (2-PEA). However, when the support was γ-alumina, the main product was phenylacetaldehyde (PAD). The basic character of the support led to the formation of the less substituted alcohol (2-PEA). This was obtained at high conversion (85%) with practically total selectivity (around 99%). However, more acid support such as γ-alumina led to the formation of the more substituted alcohol 1-phenylethanol (1-PEA) and phenylacetaldehyde, mainly due to the isomerisation of the epoxide. Consequently, the acid–base character of the support plays an important role in the selectivity of this reaction.