Oxygen removal from poor-quality refined edible oil to produce hydrocarbon-type biofuels using the hydrotreating process

Abstract

The present investigation reports the removal of oxygen from triglycerides and free fatty acids contained in low-quality refined commercial palm oil to produce green hydrocarbons. The process variables were 360 to 390 °C, 2 and 3 h of reaction time, operating at 75 bar of initial hydrogen pressure, in the presence of 4 wt% of CoMo sulfide catalyst supported on alumina, stirring the reaction mixture at 800 rpm. The characterization techniques for liquid products were nuclear magnetic resonance, simulated distillation, Fourier transform infrared spectroscopy and X-ray fluorescence; the density and viscosity of the reaction products were also determined while the absence of aromatics was established by FTIR. It was observed that at lower temperature and reaction time the green diesel fraction was favored, while at high severity the quality of the bulk liquid products improved in terms of density, viscosity and sulfur content, and also more light distillates, i.e. naphtha and kerosene, were produced at the expense of the diesel fraction. Therefore, depending on the desired fraction, appropriate reaction conditions should be applied; in the present study, the favored fraction in terms of quality and quantity is green diesel.