A high-efficient beta-zeolitic catalyst for conversion of waste cooking oil towards biodiesel

Abstract

The conversion of waste cooking oil into biodiesel can bring about dual benefits: alleviating environmental pollution and realizing waste recycle. Embryonic zeolite has highly accessible acid sites because of the partially formed or more open zeolitic structure, which can solve problems such as diffusion limitation and inaccessible acid sites that the traditional zeolite catalysts face in the process of macromolecular reactants. In this work, a series of embryonic Beta zeolites were prepared by using mesoporous SBA-15 as a self-sacrificial silica source via a solid-state transformation strategy. NH₃-TPD and FT-IR pyridine adsorption confirm that Brønsted acid sites have been created in these amorphous form embryonic catalysts. The diffusion property of toluene obtained by a zero-length column method proved that the higher the zeolization degree, the greater the diffusion activation energy. The synergistic effects resulted from the combination of the ordered mesoporous structures (ranging from 2 to 10 nm) stemming from the SBA-15 substrate and the moderate acid sites (∼88 μmol g⁻¹) offered the embryonic SBEA-3 catalyst with remarkable catalytic performance for ≥95 % conversion during 20 times cycling tests and more than 90 % methyloleate yield.