Development of heterogeneous mesoporous acid catalyst for the esterification of oleic acid with methanol.

摘要

A homogeneous or a heterogeneous acid or base catalyst is generally used in biodiesel production to increase the yield. Earlier studies showed that cornstarch was more effective than the conventional starch as a precursor in developing acid catalysts for biodiesel production in terms of yield and energy efficiency. However, heterogeneous acid catalysts suffer from a low number of acidic sites and diffusional limitations that can be theoretically improved by increasing the mesoporous nature of the catalyst, which involves further modification of the catalysts.;In this study, a heterogeneous mesoporous solid acid catalyst, derived from cornstarch, is employed to overcome the disadvantages of other catalysts mentioned above. Mesoporous acid catalysts with pore diameters ranging between 2 nm and 50 nm was attained by the expansion of starch, including gelatinization, retrogradation and dehydration via solvent exchange, followed by pyrolysis and sulfonation.;The resulting catalysts are highly active in esterification reaction of oleic acid (10 mmol) with methanol (100 mmol). Conversions of >90 % are achieved within 10 min of the reaction at 80 °C with 140 mg catalyst loading (2.3 %). 30mg catalyst loading (0.5 %) has shown >60 % conversion for the same time of the reaction (with all the parameters remaining constant). Thermal reaction was found to be as effective as ultrasonic reaction.