Catalytic and DFT study of the MgO active site participating in glycerolysis reactions toward monoglycerides

CRISTIÁN FERRETTI; SILVIA A. FUENTE; RICARDO M. FERULLO; NORBERTO J. CASTELLANI; CARLOS APESTEGUÍA; ISABEL DI COSIMO

Munich

Congreso; 15th International Congress on Catalysis 2012; 2012

Sociedad Germana de Catálisis (DECHAMA)

The synthesis of monoglycerides (MG) by glycerolysis of methyl oleate, a fatty acid methyl ester (FAME) with glycerol (Gly), was studied on MgO in a four-phase reactor at 493K with a Gly/FAME = 4.5 (molar) and a catalyst/FAME = 30 g/mol. The chemical nature of the base site responsible for the catalytic activity was investigated, both experimentally and by density functional theory (DFT). Main results indicated that Gly was much more strongly adsorbed than FAME. Dissociative chemisorption of Gly took place on low coordination O2- sites such as those on edges (strong base sites), in agreement with the catalytic results. Only one OH bond of Gly dissociated at a time in agreement with the catalytic results showing that MG are the only primary reaction products. Thus, the proton abstraction from Gly OH groups, would take place on unsaturated oxygen anions and the resulting glyceroxides would react with FAME molecules weakly adsorbed on Lewis acid sites supplied by surface Mg2+.