Synthesis of biodiesel from soybean oil and methanol catalyzed by zeolite beta modified with La3+

La/zeolite beta was prepared by an ion exchange method and used to synthesize the biodiesel (fatty acid methyl esters, FAME). The La(NO3)3 was applied as the ion exchange precursor to incorporate La ion into zeolite beta. The composition of the zeolite beta before and after ion exchange was analyzed by the SEM microphotographs and EDS spectrograms, the Brønsted and Lewis acid sites were investigated by FTIR imaging. The transesterification was carried out in a batch reactor and the composition of the FAME product was determined by a potassium hydroxide saponification method. The syntheses conditions with respect to catalytic activities have been optimized individually. Results of the experiment showed that La/zeolite beta shows higher conversion and stability than zeolite beta for the production of biodiesel, which may be correlated to the higher quantity of external Brønsted acid sites available for the reactants. The product consists of a mixture of monoalkyl esters primarily, and when the methanol/ soybean oil molar ratio was 14.5, reaction temperature at 333 K, reaction time 4 h and catalyst/soybean oil mass ratio of 0.011, the conversion of triglyceride 48.9 wt% was obtained from this optimal reaction condition.