• Production of renewable and biodegradable glycerol carbonate fuel or fuel additive. • Sustainable catalytic progress using alumina industrial waste and diethyl carbonate. • Enhanced performance of tricalcium aluminate catalyst by silica incorporation. • Rapid deactivation of katoite and chloride sodalite components of bauxite residue. • Excellent and robust activity of hydroxysodalite compared to complex composites. Bauxite residues contain katoites and desilication products (sodalite and cancrinite), which are excellent candidates for Earth-abundant heterogeneous base catalysts from industrial waste sources. For the first time, they were tested in synthetizing the renewable and promising fuel or fuel additive glycerol carbonate for the purpose of recycling glycerol by-products from biodiesel production. Incorporation of silicate was found to enhance the previously established excellent catalytic activity of tricalcium aluminate (Si-free katoite). Performance of sodalites containing four different cage anion-designed (OH, CO 3 , SO 4 , Cl) and carbonated cancrinite was determined to a much greater extent by their Brönsted OH content than by the basicity of the caged anions. Direct catalytic use of bauxite residue resulted in a glycerol carbonate yield of over 80%, but it was quickly deactivated due to the limited reusability of many of its most active components ( i.e., Si-free and Si-containing katoites, chloride sodalites). However, hydroxysodalites showed excellent reusability, with a glycerol carbonate yield of around 80% even after 5 reuses. The activity of katoites and sodalities overtook that of many complex systems containing relatively rare metals, such as Ni, Cu, Zr, and Ce. Their excellent activity has made it possible to use diethyl carbonate solvent/reagent, which is more favourable in terms of sustainability, instead of the more widely applied dimethyl carbonate, even with as short reaction times as 30–60 min.
Szabó et al. (Thu,) studied this question.