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

The hydration of α-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/SiO2, TCA/TiO2 and TCA/ZrO2·nH2O, respectively). The TCA/TiO2 catalyst converted α-pinene into hydrocarbons, while the TCA/ZrO2·nH2O 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 α-terpineol. The TCA/SiO2 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/ZrO2·nH2O 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.

Graphical abstractThe hydration of α-pinene with solid acid catalysts was carried out using catalysts impregnated with trichloroacetic acid on different supports, including silica, titania and zirconia. The catalyst supported on titania only produced hydrocarbons, while the catalyst supported on zirconia produced alcohols and hydrocarbons with a selectivity of 75% for total alcohols.Figure optionsDownload full-size imageDownload high-quality image (74 K)Download as PowerPoint slide