Conversion of 2-propanol over chromium aluminum orthophosphates

The catalytic conversion (dehydration/dehydrogenation) of 2-propanol on a series of CrPO₄-AlPO₄ (CrAlP) catalysts, which were differently prepared and thermally treated at 773–1073 K, has been studied by microcatalytic pulse reactor technique at different temperatures (473–573 K). Kinetic parameters for conversion of 2-propanol to propene have been obtained by analysis of the data through the Bassett-Habgood equation for first-order reaction processes. The influence of the reaction temperature upon alcohol conversion and product selectivities was also investigated. Catalytic performance was affected by the precipitation agent. Catalysts obtained in propylene oxide-aqueous ammonia showed the highest activity towards propene compared to other catalysts. Calcination at increasing temperatures caused a decrease in the activity due to the decrease in surface acid character. The results of dehydration to propene can be well interpreted through the differences in the number and strength of acid sites, which were gas-chromatographically measured using pyridine and 2,6-dimethylpyridine chemisorbed at different temperatures (573 and 673 K). Dehydrogenation to 2-propanone occurred to a small extent at all reaction temperatures and, besides, its conversion changed slightly with reaction temperature. Propene selectivity strongly increased with increasing reaction temperature.