KF-impregnated clam shells for biodiesel production and its effect on a diesel engine performance and emission characteristics

Natural white bivalve clam shells were calcined to obtain calcium oxide (CaO) and KF/CaO catalyst was synthesized by impregnating potassium fluoride (KF) on calcined clam shells. This solid catalyst was tested for transesterification of waste frying oil. A high biodiesel yield of 95.77% was obtained at methanol/oil molar ratio of 9:1, catalyst amount of 4 wt % (based on oil weight), reaction temperature of 65 degrees C and reaction time of 2 h. The performance and emission characteristics of a single cylinder, four stroke direct injection diesel engine using conventional diesel and biodiesel blends (B20, B40, B60, and B80) at various loads were measured and compared. The results indicated that the higher brake specific fuel consumption (BSFC) and the lower brake thermal efficiency (BTE) were observed for biodiesel blends when compared with the conventional diesel. Emissions of HC and CO were reduced significantly whereas NOx emission was increased with increased proportion of biodiesel in the fuel blends. (c) 2014 American Institute of Chemical Engineers Environ Prog, 34: 1166-1173, 2015