Comparison of the Homogeneous catalysed & Heterogeneous catalysed biodiesel production from waste frying oils

In recent years, due to the increase in greenhouse gas emissions, air pollution and other problems associated with the fossil fuels, the environmental friendly biodiesel fuel has been receiving much more attention as an alternative fuel to be used in conventional compression-ignition engines. Moreover, application of waste frying oils as a low cost feedstock for biodiesel production has increased recently because of the environmental impacts caused by the disposal of this waste oils, that can be eliminated in this way. The goal of this work was to compare the transesterification process of waste frying oils with methanol for biodiesel preparation using three kinds of catalysts: basic homogeneous KOH, acidic homogeneous H2SO4 and basic heterogeneous CaO. Under the optimum reaction conditions, the results showed yield of biodiesel to 89.6%, 66.1% and 90.3%, respectively. Also, the biodiesels were characterised by FT-IR and some of their chemical properties were evaluated according to standard test methods and were compared to those of the conventional diesel fuel. The properties evaluated were flash point, density, kinematic viscosity, pour point and acid value which satisfied the requirement of relevant international standards.

کلیدواژه ها:

Biodiesel ، Waste frying oil ، Heterogeneous catalyst ، low cost feedstock