Impact of Chain Length of Saturated Fatty Acids during Their Heterogeneously Catalyzed Deoxygenation

Abstract

Fatty acids with different chain length were deoxygenated in the absence of hydrogen (caprylic acid (CA), lauric acid (LA) and stearic acid (SA)). The catalytic tests were carried over Pd-containing catalysts out in a batch reactor under inert gas for 6 h at 250˚C to 350˚C and pressures from 18 to 75 bar in the absence of additionally fed hydrogen. Pd-containing catalysts were tested; the best performing catalyst was 10% Pd/C with 63% undecane yield at 327˚C. These catalysts were used for a comparative decarboxylation of CA, LA and SA. At equal reaction conditions (300˚C, 6 h), the chain length of the fatty acid had a strong impact on the conversion, which was steadily increasing, whereas the alkane selectivity ran through a maximum. This work demonstrated the usability of Pd-containing catalysts for the decarboxylation of various fatty acids in the absence of additionally fed hydrogen with respect to the manufacture of hydrocarbons that can be used as blending components for fuels.