Abstract

The present study investigated the production of biodiesel from Jatropha curcas,Azadirachta indica, Hevea brasiliensis oil seed via transesterification methods: base catalysed and supercritical methanol, a catalyst-free process, as a cleaner alternative to conventional chemically catalyzed process. In biodiesel production using base catalyzed transesterification, temperature, methanol: oil molar ratio, catalyst type, catalyst concentration and agitation were found to have significant role on ester conversion. For supercritical transesterification method, reaction was performed in a tubular reactor, at 250°C, with 200 rpm, varying the pressure in the range from 1 to 100 bars. The results obtained showed that non-catalytic supercritical methanol technology required 3, 4, 5 min reaction time to produce 98, 97.17 and 87.1% biodiesel from J. curcas, A. indica and H. brasiliensis seed oil, respectively. Compared to conventional catalytic methods, which required at least 1 h reaction time to obtain similar yield, supercritical methanol technology has been shown to be superior in terms of time and energy consumption. Apart from the shorter time, it was found that separation and purification of the products were simpler since no catalyst is involved in the process. Hence, formation of side products such as soap in catalytic reactions does not occur in the supercritical methanol method.

Key words: Biodiesel, Jatropha curcas, Azadirachta indica, Hevea brasiliensis,supercritical