The aim of this work is to study and test two types of catalyst – acid and basic for the preparation of methyl esters. The first goal is to describe the transesterification catalysed by Mg-Al mixed oxides in a broad range of Mg/Al ratio (from 1.0 to 8.4) including the relation between the variables by statistical analysis and catalyst stability. The mixed oxides with a different Mg/Al molar ratio were synthesized by thermal pre- treatment of hydrotalcite at 450 °C. The influence of the Mg/Al molar ratio on the yield of ester, leaching of magnesium and catalyst properties such as the concentration of basic sites, crystallite size of MgO and specific surface area were studied. It was found that the crystallite size and the yield of ester increases and the concentration of basic sites decreases with an increasing Mg/Al molar ratio; the specific surface area does not depend on the Mg/Al molar ratio. The relation between the variables was described by statistical analysis (the correlation matrix and principal component analysis). There was observed only negligible magnesium leaching from solid Mg/Al mixed oxides to the liquid phases. Five types of zeolites (MOR-C and D, ZSM-5, Y and mesoporous BEA) were tested in the esterification of oleic acid and the results were compared with pure alumina. The highest yield exhibited mesoporous BEA. The comparison of catalytic and non-catalytic esterification was carried out at the same reaction conditions.
