Hydrocarbon Fuels From Gas Phase Decarboxylation of Hydrolyzed Free Fatty Acid

Abstract

Gas phase decarboxylation of hydrolyzed free fatty acid (FFA) from canola oil has been investigated in two fix-bed reactors by changing reaction parameters such as temperatures, FFA feed rates, and H2-to-FFA molar ratios. FFA, which contains mostly C18 as well as a few C16, C20, C22, and C24 FFA, was fed into the boiling zone, evaporated, carried by hydrogen flow at the rate of 0.5–20 ml/min, and reacted with the 5% Pd/C catalyst in the reactor. Reactions were conducted atmospherically at 380–450 °C and the products, qualified and quantified through gas chromatography-flame ionization detector (GC-FID), showed mostly n-heptadecane and a few portion of n-C15, n-C19, n-C21, n-C23 as well as some cracking species. Results showed that FFA conversion increased with increasing reaction temperatures but decreased with increasing FFA feed rates and H2-to-FFA molar ratios. The reaction rates were found to decrease with higher temperature and increase with higher H2 flow rates. Highly selective heptadecane was achieved by applying higher temperatures and higher H2-to-FFA molar ratios. From the results, as catalyst loading and FFA feed rate were fixed, an optimal reaction temperature of 415 °C as well as H2-to-FFA molar ratio of 4.16 were presented. These results provided good basis for studying the kinetics of decarboxylation process.