Effect of Selected Factors on Catalytic Activity of Bimetallic Copper-Gold Catalysts in Selective Oxidation of Glycerol

A current problem in petrochemical industry is the elimination of crude glycerol which is the by-product of biodiesel production obtained during the transesterification of vegetable oils and animal fats. In this work are presented the results of characterisation of mesoporous ceria, zirconia and mixed cerium-zirconium oxide modified with gold and/or copper species and their application as catalysts in the selective oxidation of glycerol in the liquid phase. The characterisation of samples was performed using selected advanced techniques (ATR-FTIR, UV-vis, XRD, adsorption and desorption of nitrogen, XRD, XPS, TEM, SEM, STEM-EDXS). The obtained data show that the bimetallic Cu-Au systems supported on mesoporous ceria, zirconia or mixed cerium-zirconium oxide are more active and selective in glycerol oxidation to glyceric acid in basic solution than acidic conditions. The data of HPLC analysis provided that glyceric acid was the first stable product in the liquid phase during the oxidation process in alkali media. It is worth noting that the bimetallic Cu-Au catalysts were characterised also by the catalytic stability, because the increase of selectivity to glyceric acid during the recycling of Cu-Au catalysts was achieved. The influence of selected factors (oxygen source, pH solution, oxygen pressure, base content and stirring speed) on the catalytic activity of Cu-Au catalysts will be presented and discussed.