Abstract:
The mechanism of the hydrogenation of butyric acid and methyl butyrate over NiMo/Al₂O₃ and Pd/C catalysts was studied. Possible intermediates i.é. butanal and n-butanol also tested to confirm the reaction pathways. The reactions were carried out in a packed-bed reactor under temperatures of 250-350°C, pressures of 200-600 psig, H₂/feed ratio of 2.5, and LHSV of 2.0 h⁻¹. The results show that Pd/C was selective to the hydrodecarbonylation path, resulting in propane as the main product. At the same time, butane, which occurred via hydrodeoxygenation, was slightly increased with increasing reaction pressure. For NiMo/Al₂O₃, the reaction pressure significantly affects the product selectivity, as butane was mainly observed at high pressure and propane was mainly observed at low pressure. However, coupling ester, butyl butyrate was considered as the major competitive product, especially on NiMo/Al₂O₃. The intermediates found in the product were butanal and n-butanol. Moreover, condensed products produced via etherification and ketonic decarboxylation reaction which are dibutyl ether, and 4- heptanone and heptane were also observed.
