Flash pyrolysis of myristic acid adsorbed on supported nickel catalysts for biofuel production

The present work is part of a more general project aiming at studying the decomposition products formed during the pyrolysis of fatty compounds adsorbed on solid catalysts. It deals with the decomposition of myristic acid in contact with nickel-supported catalysts. The pyrolysis was performed at 650 °C in a flash mode. The products were analyzed on-line through a GCMS setup. The catalysts were prepared by impregnation with nickel nitrate, dried at 110 °C and heat treated at 600 °C before use. Solid myristic acid was added at room temperature to the dehydrated catalyst by mechanical mixing followed by heat treatment at 120 °C under intense manual mixing, in order to allow the liquid myristic acid to wet the catalyst surface. The catalysts precursors and the catalysts containing myristic acid were characterized by DTG, and the catalysts in their oxide form were characterized by TPR and XRD. The catalysts containing adsorbed myristic acid were also characterized by FTIR. Compared with Ni/silica producing a high amount of linear 1-olefins during flash pyrolysis, the contents of deoxygenated products, of poly olefins and aromatics, were higher with the Ni/alumina catalyst. The presence of carboxylic acids with a chain length between 6 and 12 C in the pyrolysis products on the Ni/silica catalyst suggests that the cracking along the carbon chain occurred parallel to reactions of decarbonylation and decarboxylation. We also found a direct demethylation route with the Ni/silica catalyst in this experiment.