Conversion of 5-Methyl-3-Heptanone to C8 Alkenes and Alkane over Bifunctional Catalysts

A one-step catalytic process was used to catalyze the hydrodeoxygenation of 5-methyl-3-heptanone (C-8 ketone) to a mixture of 5-methyl-3-heptene, 5-methyl-2-heptene (C-8 alkenes), and 3-methyl heptane (C-8 alkane). High conversion of C-8 ketone to the desired products was achieved over a single bed of a supported catalyst (bifunctional heterogeneous catalyst) consisting of one transition metal (copper (Cu) or platinum (Pt)) loaded on alumina (Al2O3) under mild operating conditions (reaction temperatures were varied between 180 degrees C to 260 degrees C, and the pressure was 1 atm). The C-8 ketone was hydrogenated to 5-methyl-3-heptanol (C-8 alcohol) over metal sites, followed by dehydration of the latter on acid sites on the support to obtain a mixture of C-8 alkenes. These C-8 alkenes can be further hydrogenated on metal sites to make a C-8 alkane. The results showed that the main products over copper loaded on alumina (20 wt% Cu-Al2O3) were a mixture of C-8 alkenes and C-8 alkane in different amounts depending on the operating conditions (the highest selectivity for C-8 alkenes (similar to 82%) was obtained at 220 degrees C and a H-2/C-8 ketone molar ratio of 2). However, over platinum supported on alumina (1 wt% Pt-Al2O3), the major product was a C-8 alkane with a selectivity up to 97% and a conversion of 99.9% at different temperatures and all H-2/C-8 ketone ratios.