Study of solid acid catalysis for the hydration of α-pinene

The hydration of alpha-pinene using solid acid catalysts was studied. The catalysts were prepared by impregnating trichloroacetic acid (TCA) on different supports such as silica, titania and zirconia (TCA/SiO(2), TCA/TiO(2) and TCA/ZrO(2)center dot nH(2)O, respectively). The TCA/TiO(2) catalyst converted a-pinene into hydrocarbons, while the TCA/ZrO(2)center dot nH(2)O catalyst was active and selective for producing alcohols, with a conversion of 57% and a selectivity of 75% of total alcohols, and showed 57% selectivity for a-terpineol. The TCA/SiO(2) sample did not show catalytic activity due to the elimination of the trichloroacetic acid during the preparation step of the catalyst. An additional stability study was performed with the TCA/ZrO(2)center dot nH(2)O sample. The presence of TCA in the different impregnated samples was studied using FT-IR, and the TCA content was determined by thermogravimetric analysis. The surface content of TCA in fresh and used catalysts was studied with XPS, and the textural properties and crystalline structures were analysed by BET and XRD, respectively. Additionally, the nature of the acid centres was characterised by pyridine adsorption coupled with FT-IR, and the acidity was determined by potentiometric titration. (C) 2010 Elsevier B.V. All rights reserved.