Engineering Pt-O-W interface to enhance the selective hydrogenolysis of glycerol to 1,3‑propanediol Dongpei Zhang China University of Petroleum, China
Introduction 1,3-Propanediol (1,3-PDO) is regarded as the key value-added intermediate for the manufacture of polyester fibers, antifreezes and packaging materials. While the biological route for 1,3-PDO synthesis suffers from low productivity and cost-ineffective purification processes, selective glycerol hydrogenolysis into 1,3-PDO provides a promising alternative but remaining a grand challenge in this area.[1] This is because that, current catalyst design strategies are primarily focused on spatial distribution of both Pt and WO x species on solid supports. [1] Consequently, the intrinsic Pt-WO x interfaces for selective activation of internal C-OH groups are yet to be established in literature. Besides, the interfacial Pt-WO x electronic coupling between Pt 5d or W 5d orbitals on controllable activation of C-H and O-H bonds is largely unexplored in both academia and industry. Therefore, in this work, we employed Pt-WO x interfacial catalysts as a representative example, and demonstrated an unusual Pt-loading dependent electronic coupling trend for selective hydrogenolysis of glycerol into 1,3-propanediol. Results and Discussion Pt/W/Al catalysts with different Pt loadings show distinct amounts of Pt-WO x interfaces. Based on the XRD spectra, the (0 2 2)/(2 -2 2) lattice planes of WO x species were found combined with Pt species with the increasing Pt loading [Figure 1 (a)]. For glycerol conversion, the conversion rate of glycerol per gram Pt and the selectivity of 1,3-PDO both increased gradually with the Pt loading [Figure 1 (c)]. The 6Pt/W/Al catalyst exhibits the best catalytic performance with a highest conversion rate and the maximum 1,3-PDO selectivity (54.4%) at 180 o C and 4 MPa H 2 . As shown in the UV−Vis DRS spectra [Figure 1 (b)], the edge energy of the Pt/W/Al catalysts decreased with the Pt loading increasing (from 2.49 eV to 2.05 eV). Besides, XPS spectra was employed to determine the electron transfer between Pt and WO x on the catalyst surface. As shown in the XPS spectra, the binding energy of Pt did not shift, while the binding energy of W decreased (Peak of W 4f 7/2 spectra: from 36.4 eV to 35.85 eV) as the Pt loading increased, indicating that the holes (in O 2p orbitals) are more likely to be produced by the motivation of photoelectrons with the Pt loading increasing. Besides, the W 5+ /(W 5+ +W 6+ ) ratio increased from 45.9% to 47.1%, and the reduced average valence of W species indicated that the increase of Pt species promoted increasing the electron density of W species, and enhanced catalytic performance, which is in agreement with Zhu’s [2] research. This reveals that the change of Pt loading led to the formation of more holes in O 2p orbitals, contributing to charge transfer from O atoms to W atoms, and then result in the increasing edge energy and improved catalytic performance.
Figure 1 . (a) Structure model (b) Edge enegy (c) Catalytic performance of as-synthesizedxPt/W/Al catalysts.
References 1. B. Wang, ACS Sustainable Chemistry & Engineering 9(16) (2021) 5705-5715. 2. S. Zhu, Journal of Molecular Catalysis A: Chemical 398 (2015) 391-398.
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© The Author(s), 2022
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