Transesterification and hydroprocessing of sunflower oil over heterogeneous catalysts

Abstract

A large part of global energy is being supplied by fossil fuels, crude oil being the primary source of energy and chemicals. Fossil fuel consumption is not sustainable as their reserves are not expected to last forever. Besides, the global warming experienced presently due to CO2 build up in the atmosphere is attributed mainly to the use of fossil fuels. It is, therefore, necessary to substitute the rapidly depleting petroleum fuels, a major portion of which is used for transportation purposes, with carbon-neutral and renewable fuels such as those derived from biomass. This thesis reports i) the use of supported MoO3 and spinel-type (AB2O4) materials, that are much greener and more advantageous than the presently used soluble alkali catalysts, in the transesterification of vegetable oils, and ii) the hydroprocessing of sunflower oil and gas oil blends over sulfided Ni-Mo-zeolite beta/alumina catalysts. All the samples were characterized by different techniques and their activity for the transesterification of sunflower oil was studied. The results revealed a correlation between Zn content in supported ZnO samples and transesterification activity. The activity of ZnAl2O4 and ZnFe2O4 was also investigated using a fixed-bed reactor. An analysis of the ratios of the n-C18 and n-C17 paraffins formed from the vegetable oil revealed that the catalyst containing 15% BEA was the most active one for HDO. Besides, the hydrodesulfurization (HDS) activity of Ni-Mo-Al2O3 was enhanced by the addition of BEA. The studies have revealed the feasibility of hydroprocessing of both edible and non-edible oil gas oil blends in hydrotreating units using Ni-Mo-BEA-Al2O3 without loss of HDS performance. In summary, the studies have identified i) MoO3/Al2O3 and Zn-spinels as suitable solid catalysts for transesterification of vegetable oils and ii) Ni-Mo/Al2O3 promoted with beta zeolite to be a good catalyst for the hydroprocessing of vegetable oil-gas oil blends. newline newline newline