Selective vapour-phase α-pinene isomerization to camphene over gold-on-alumina catalyst

Article abstract of DOI:10.1016/j.apcata.2010.07.002

The vapour-phase isomerization of α-pinene for the first time was studied over a supported Au catalyst. α-pinene was isomerized to camphene over the 2.2% Au/γ-Al₂O₃ catalyst at 463-483 K using a solution of the reagent in n-octane as the initial reaction mixture and H₂ or N₂ as a carrier gas. Under these conditions, the selectivity to camphene reaches 60-80% at 99.9% conversion of α-pinene. The reaction is found to be first-order with respect to α-pinene, the apparent activation energy being similar to that observed with the conventional TiO₂ catalyst. The prominent catalyst deactivation has been observed at increased α-pinene concentrations in the inlet reaction mixture (≥4 vol% in n-octane solution). According to HRTEM and TPO results, the deactivated catalyst contains the carbonaceous deposits that may block the catalyst surface. Almost complete regeneration was done in flowing O₂ at temperature up to 923 K required to totally eliminate the coke deposits.