(140f) Application of Coal Fly Ash as a Catalyst in the Transesterification Reaction for Biodiesel Production

South Africa is largely dependent on the combustion of coal for electricity production; millions of tonnes of fly ash are generated worldwide every year to satisfy the large demand for energy and management of this fly ash has been a concern with various approaches for its beneficial use being investigated. This work presents the results of transesterification reaction using sunflower oil as feedstock with methanol done in the presence of a class F fly ash catalyst derived from a coal fly ash dump in South Africa to produce methyl esters (biodiesel). The fly ash based catalyst was prepared using the wet impregnation procedure with different loadings of potassium and was characterized by powder X-ray diffraction (XRD), FTIR spectroscopy, CO2 temperature- programmed desorption (CO2-TPD). The XRD patterns obtained indicated that the structure of the support gradually deformed with an increase in the loading and the extent of decomposition of KNO3 varied with the amount of loading. The influence of various reactions parameters such as loading amount of active components, methanol:oil ratio, reaction time, temperature and catalyst deactivation are investigated. The fly ash based catalyst loaded with 5% wt KNO3 ¬ at a reaction temperature of 160ºC exhibited maximum oil conversion (82.3%). The biodiesel synthesized was tested and important fuel properties of the methyl esters (Biodiesel) compare well with ASTM biodiesel standards having a viscosity value of 4.8 Cst @ 40ºC and flash point of 150 ºC.