(560gq) Structure-Property Relations of PtWOx/C Inverse Catalysts

Authors: 
Fu, J., University of Delaware
Liu, S., University of Delaware
Zheng, W., University of Delaware
Wang, C., University of Pennsylvania
Caratzoulas, S., University of Delaware
Gorte, R. J., University of Pennsylvania
Vlachos, D. G., University of Delaware
Owing to the strong synergy between Pt and WOx, the PtWOx catalyst has been found to be efficient for a number of important reactions such as the oxidation of propane1, ring-opening of tetrahydrofurfuryl alcohol2 and hydrodeoxygenation of biomass derived compounds3,4,5. Accumulated knowledge underscores that the close proximity of Pt and WOx is crucial. However, catalysts prepared via conventional methods are heterogeneous in composition and particle size, rendering the establishment of structure-property relations difficult. Recently, atomic layer deposition (ALD) has been employed deposit a near monolayer of WOx film on the surface of carbon-supported Pt. Comparing to the conventionally prepared PtWOx catalysts, the inverse catalyst has demonstrated much higher efficiency for ring opening of tetrahydrofurfuryl alcohol.2 It has been proposed that the partially reduced WOx acts as a Brønsted acid that activates C-O bonds and stabilizes cationic intermediates.2 However, the interaction between Pt and WOx remains elusive. Structure-function correlations of the PtWOx/C catalysts under working conditions are still lacking.

In this study, we use probe molecules, e.g., alcohols, to investigate the Brønsted acid sites on WOx (@Pt) under different reaction environments and pretreatment conditions. Those probe molecules undergo acid-catalyzed elimination reactions and are sensitive to the configurational changes of PtWOx catalyst during reaction. Combined strategies including kinetics, theoretical calculations as well as operando characterization reveal an intriguing interplay between Pt and WOx.

References:

1. Wu, X. et al. Total Oxidation of Propane on Pt/WOx/Al2O3 Catalysts by Formation of Metastable Pt1+ Species Interacted with WOx Clusters. J. Hazard. Mater. 225–226, 146–154 (2012).

2. Wang, C. et al. A Study of Tetrahydrofurfuryl Alcohol to 1,5-Pentanediol Over Pt-WOx/C. Catal. Letters 148, 1047–1054 (2018).

3. Janampelli, S. & Darbha, S. Selective and Reusable Pt-WOx/Al2O3 Catalyst for Deoxygenation of Fatty Acids and Their Esters to Diesel-range Hydrocarbons. Catal. Today 309, 219–226 (2018).

4. Wang, J. et al. Hydrogenolysis of Glycerol to 1,3-propanediol under Low Hydrogen Pressure over WOx-Supported Single/Pseudo-Single Atom Pt Catalyst. 116023, 784–790 (2016).

5. Wang, C. et al. Mechanistic Study of the Direct Hydrodeoxygenation of m-Cresol over WOx-Decorated Pt/C Catalysts. ACS Catal. 8, 7749–7759 (2018).