Heterogeneous catalytic transesterification of waste vegetable oil using modified natural zeolite

Keywords: biodiesel, clinoptilolite, waste vegetable oil, transesterification


Objectives: In the search of an economical process for biodiesel synthesis, waste cooking oil was analyzed as a potential feedstock. The influence of different concentrations and granulations of the zeolite catalyst on the yield and quality of the final product was also investigated.

Methods: The pretreatment of waste oil was carried out using the simple processes of filtration and drying with CaCl2, after which its physicochemical properties were determined. Transesterification of waste oil with methanol was carried out using zeolite clinoptilolite as the catalyst. Its preparation included modification with sodium hydroxide, drying at 105°C and calcination at 300°C. As for the waste oil, the density, acid and peroxide number, moisture content, kinematic viscosity and flash point of the obtained biodiesels were determined by standardized methods. After the synthesis, the Fourier transformation infrared (FT-IR) spectra of the obtained biodiesel and waste cooking oil were recorded and compared.

Results: The process of transesterification with methanol was found to be suitable due to the high conversion of waste oil esters under relatively mild reaction conditions. Moreover, modified natural clinoptilolite proved to be a suitable catalyst for the process of biodiesel production. At each catalyst concentration and granulation, the biodiesel yield was satisfactory and its quality parameters met the prescribed standards.

Conclusion: The basic characteristics of the biodiesel obtained from waste cooking oil enable its potential application. Moreover, the properties of clinoptilolite, such as concentration and particle size, can be adjusted for each transesterification process to attain high quality product. The performed experiment presents an example of the efficient linking of biofuel production and waste oil disposal processes.

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