Zirconium–Cerium Oxides Supported on SBA-15 as Catalyst for Shape-Selective Synthesis of Lactic Acid from Glycerol

Abstract

The conversion of an oleochemical waste i.e. glycerol into lactic acid (LA) using bifunctional catalyst is receiving intensive research attention. The major concern is to achieve a suitable combination of the non-precious active metals with specific roles to achieve a fast and selective reaction. Catalyst with a Ce-to-Zr ratio of 1:2 and supported on SBA-15 at total active metal loadings between 10 and 40 wt% were prepared via a two-sequential-step post-impregnation method. The catalysts were then characterized using nitrogen adsorption–desorption and SEM analyses to elucidate their properties. They were then employed in selective glycerol oxidation reaction carried out at between 240 and 280 °C for up to 3 h to yield LA. The catalytic performance in terms of glycerol conversion and lactic acid yield was successfully correlated with the physicochemical properties of the catalysts. The highest glycerol conversion of 91.2% of glycerol was obtained using 10 wt% of CeZr/SBA-15 at a catalyst loading of 25 wt% with almost 51.4% of corresponding LA yield. It was attributed to the desired shape selectivity effect in the benzylic rearrangement (Cannizzaro reaction) of pyruvaldehyde to suppress by-product formations.