Controlling micro- and nanostructure and activity of the NaAlO₂ biodiesel transesterification catalyst by its dissolution in a mesoporous γ-Al₂O₃-matrix

Mesoporous alumina and alumina–sodium aluminate composites were obtained by sol–gel method using polyethyleneimine as template. New approach for the regulation of the micro- and nanostructure of the composites as catalytic materials was proposed, exploiting inorganic seeds for the control of morphology for the produced nanostructures. Composition and temperature window for preventing the leaching of sodium aluminate in the course of reaction and thus drastically improving the catalytic activity has been identified. Structure and phase composition of the thus obtained catalytic materials were characterized using X-ray diffraction, N₂ adsorption/desorption, FTIR spectra, scanning electron microscopy, and thermal analysis. New type of catalyst has shown high efficiency in the vegetable oil transesterification process under mild conditions opening prospects for small-scale production of reasonably good-quality biodiesel fuel.

Dissolving sodium aluminate in the alumina matrix at proper compositions and under controlled temperatures permits to drastically decrease the leaching of aluminate and maintain its high catalytic activity in transesterification of vegetable oils with methanol.