Catalytic study of Sulphated Zirconia from Conventional and Modified Conventional Methods for Fatty Acid Methyl Ester

摘要

Sulphated zirconia was synthesized using different volume of sulphating agent in order to optimise its catalytic property: (1) in the first case the "conventional" 15 ml H_2SO_4 to lg of ZrOH for impregnation was used in wet-precipitation method and the catalyst designated 'wp' and (2) same procedure but with modification in volume of acid; 2 ml of H_2SO_4 was used for lg of ZrOH, 'mwp'. The properties of uncalcined and calcined catalysts were examined by various techniques: EDX, XPS, XRDP, Py-DRIFTS and BET nitrogen adsorption techniques. The sulphur content in the uncalcined 'mwp' and 'wp' catalysts was 0.07 mol each whereas the calcined catalysts were 0.07 mol and 0.05 mol for 'mwp' and 'wp' respectively. BET surface area was determined to be 65.0 m~2/g for wp and 101m~2/g for 'mwp'. The effect of the variation of sulphating agent on the catalyst activity was investigated in catalytic cracking of triglycerides for fatty acid methyl esters. Sulphated zirconia from the modified conventional method was found to perform better than the conventional wet-precipitated sulphated zirconia. Furthermore, 'mwp' retained approximately 74 % of its sulphur content after 3 h reaction whereas 'wp' catalyst lost 100 % during the reaction as indicated by SEM-EDX. Interesting the results show variation in characterization and in their selectivity to different types of fatty acid methyl esters under the same reaction conditions. The 'mwp' catalyst showed higher catalytic activity for methyl ester yield of 40 % as well as higher selectivity for saturated methyl esters.