| Summary: | The issues of energy security, climate change, and environmental protection attract the use of biodiesel as an alternative fuel worldwide despite several potential setbacks such as deforestation and escalating food prices. A better biodiesel production scheme is needed to reduce the setbacks, to increase the economical value, and to have a safer production process. The use of waste oil and fat as feedstock, and conversion of glycerol into fuel oxygenates are the key solutions in this scheme. Motivated by the high activity of the sugar catalyst, a low surface area and non-porous carbon-based catalyst, this study investigates the synthesis of mesoporous, high surface area and acidity carbon-based catalysts that are active for the conversion of oleic acid and glycerol into biodiesel and fuel oxygenates, respectively. The results showed that a silica templating technique, prepared via confined activation process, was effective for synthesizing mesoporous and high surface area catalyst, but low in total acidity. The technique of catalyst functionalization in liquid fuming sulfuric acid was effective, but destroyed the internal pores of the char. The activity of the mesoporous catalyst was lower than the sugar catalyst in esterification of oleic acid. The catalyst activity was dependant on the total acidity, but independent of surface area and porosity. Further investigation showed that multiple vapour phase sulfonation was effective in synthesizing higher acidity catalyst while maintaining the mesoporous and high surface area structure. Vapour phase sulfonation caused less pore destruction in the char compared with liquid phase sulfonation. Repeated vapour phase sulfonation was effective in loading increased functional groups on the catalyst at the expense of its surface area. Evaluation of the activities of carbon-based catalysts on esterification of oleic acid showed that it depended on density and accessibility of active sites, and catalyst deactivation. Evaluation of etherification of glycerol showed that all catalysts, despite having huge differences in surface area, had comparable activity per unit mass. The carbon-based catalysts had a high selectivity to di- and tri- glyceryl ethers. In conclusion, the carbon-based catalysts synthesized through multiple vapour phase sulfonation processes are promising catalysts for a better biodiesel production process.
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