1,3-Propanediol (1,3-PDO) is an important chemical intermediate, and can be used as the monomer of polypropylene terephthalate (PTT), which is a new kind of polyester material with excellent function. Glycerol hydrogenolysis to 1,3-PDO is a green route which can not only relieve the pressure of environmental change, but also contribute to the development of biodiesel industry chain. Because of the high 1,3-PDO selectivity, WOx based bifunctional catalysts are widely used in glycerol hydrogenolysis. However, the intrinsic structure of Brönsted acid is unclear and its controllable preparation has not been investigated in detail. In addition, many reaction mechanisms have been proposed up to now, but with few direct evidences in spectroscopy studies. Here, we report two methods (changing WOx loading and Mn doping) to adjust the WOx domain size of Pt/WOx/ZrO2 catalysts under monolayer dispersion threshold, and their performances were investigated in glycerol hydrogenolysis. The formation of 1,3-propanediol is found to be structurally sensitive to the polymerization degree of WOx domains, with medium sized WOx being of benefit to 1,3-PDO. WOx structure and acid properties of these catalysts were comprehensively characterized. It is confirmed that Pt-(WOx)n-H is the catalytic active structure, providing super strong Brönsted acid site and metallic Pt site adjacent to each other. The 2° -OH group of glycerol is strongly adsorbed and activated on Brönsted acid site at reaction temperature, and the active hydrogen species participated in the reaction is the one that weakly adsorbed on Pt surface, confirmed by infrared spectroscopy. Combined with the in situ infrared study of 2-propanol hydrogenolysis, the mechanism of 1,3-PDO formation is proposed to be involved with steps of secondary carbonium formation and stabilization on super strong Brönsted acid, and the direct attack of activated hydrogen from Pt surface.

Glycerol hydrogenolysis to 1,3-propanediol over Pt-WOx catalysts

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.