Production of hydrogenated biodiesel over palladium supported titania catalyst: effect of triglyceride-based feedstocks

Abstract

Hydrogenated biodiesel is one of the most promising renewable fuels. It has many advantages over conventional biodiesel, including higher cetane number, higher heating value, lower viscosity, and lower corrosiveness due to its absence of oxygen. From previous work, Pd/TiO2 gave high conversion and selectivity in hydrogenated biodiesel. In this work, the effect of triglyceride-based feedstocks (i.e. beef fat, chicken fat, pork fat, jatropha oil, and palm oil) on the production of hydrogenated biodiesel over Pd/TiO2 was studied. All feedstocks were analyzed by ICP-OES (inductively coupled plasma optical emission spectrometry) to identify the content of impurities (i.e. P, K, Ca, Na, and Mg). The deoxygenation catalyst, Pd/TiO2, was prepared by incipient wetness impregnation (IWI) and tested in a continuous flow packed-bed reactor at 325 °C, 500 psig, LHSV of 4 h-1 and H2 to feed molar ratio of 30 for its catalytic activity and selectivity of hydrodeoxygenation. All feedstocks gave high selectivity in the diesel specification range of hydrocarbons. The main hydrocarbons were n-pentadecane (n-C15) and n-heptadecane (n-C17), which resulted from the decarbonylation/decarboxylation reaction. The conversion of triglycerides in jatropha oil was higher than those of chicken fat, pork fat, beef fat, and palm oil, respectively. The higher concentration of metal impurities in the feedstock caused the deactivation of catalyst, thus lowering the conversion of triglycerides.