Insight into the effect of support crystal form on semi-continuous oxidation of glycerol

摘要

In this work, two Pt catalysts using anatase and rutile as supports were prepared, and then the support effect on catalytic performance in glycerol oxidation was investigated. Different Pt/TiO2 catalysts exhibited not so negligible distinction on the product distribution. On one side, the C=O bonds of intermediate glyceraldehyde (GLYAD) highly dissociated in the form of bidentate species through C atom bonding to O atom and O atom bonding to Ti atom of rutile support, which largely promoted the transformation from GLYAD to glyceric acid (GLYA). While, in the case of anatase support, the adsorption form of C=O was monodentate. On another side, the formed GLYA was weakly adsorbed through two O atoms bridging/bonding to two Ti atoms. Due to the longer Ti-Ti distance in anatase, C-C cleavage of GLYA was obviously inhibited. The rutile support with shorter Ti-Ti distance inevitably led to obvious C-C cleavage. The discovery of the support effect could offer an alternative method to controllably regulate product distribution and offers specific perspective on designing efficient catalysts in semicontinuous oxidation reactions.