zinc-chromium oxide catalyst for gas-phase ketonisation of pentanoic acid

Oxides of Zinc and Chromium mixed catalyst with different atomic ratios of Zinc and Chromium were tested in the ketonisation of pentanoic acid in the gas phase. These catalysts were active to form 5-nonanone, at 300 – 400 ^oC and ambient pressure.  It found that Zn-Cr with an atomic ratio (10:1) gave the best catalytic performance in  comparison with other oxides with higher or lower atomic ratio of Zn and Cr mixed oxides, ZnO and Cr₂O₃. In this test, Zn-Cr (10:1) gave 82% selectivity of 5-nonanone as the main product at 86% conversion of acid at 350^oC. The catalyst showed stable performance at the best selected conditions with a small decrease of acid conversion. For catalyst characterization, BET surface area and porosity technique, X-ray diffraction and DRIFTS of pyridine adsorption were used.