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Intrinsically Bifunctional and Tunable Tungsten Carbide Catalysts Enable Efficient PVC-Compatible Polyolefin
Uchenna C Nwachukwu1, Matthew J Moegling1, Sinhara M H D Perera2
1Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44304, United States.
Journal of the American Chemical Society
|December 17, 2025
Summary
Tungsten carbides (WxC) offer a novel solution for chemical recycling of polyolefins (PO), overcoming chlorine deactivation and transport limitations of conventional catalysts. These earth-abundant materials show superior efficiency and stability for hydrocracking challenging polymer feedstocks.
Area of Science:
- Materials Science
- Catalysis
- Chemical Engineering
- Polymer Chemistry
Background:
- Hydrocracking is a key process for chemical recycling of polyolefins (PO) into valuable hydrocarbons.
- Conventional noble metal/zeolite catalysts are deactivated by chlorine from polyvinyl chloride (PVC) and suffer from poor transport of polymer intermediates.
- Lack of site intimacy and micropore limitations hinder the efficiency of existing bifunctional catalysts for polymer hydrocracking.
Purpose of the Study:
- To develop novel bifunctional catalysts that overcome the limitations of conventional materials for polyolefin hydrocracking.
- To investigate tungsten carbides (WxC) as earth-abundant, heteroatom-compatible alternatives for chemical recycling of polyolefins.
- To explore the structure-activity relationships and catalytic performance of WxC in hydrocracking polyolefins, including those containing PVC.
Main Methods:
- Synthesis of tungsten carbide (WxC) catalysts with tunable metal and Brønsted acid sites (BAS) via controlled carburization.
- Characterization of WxC catalyst phases (W/W2C and WOx species) and their proximity.
- Evaluation of catalytic performance in polyolefin hydrocracking, including kinetic studies and assessment of activity with PVC-containing feedstocks.
Main Results:
- Tungsten carbides (WxC) exhibit bifunctional activity with closely integrated 'metal' sites (W/W2C) and BAS (WOx-OH).
- Catalyst activity shows a volcano-shaped trend with the metal:BAS ratio, optimized via carburization temperature.
- WxC catalysts demonstrate over an order of magnitude higher per-BAS efficiency than conventional catalysts due to enhanced polymer transport and maintain activity with 10 wt% PVC.
Conclusions:
- Transition-metal carbides (WxC) are effective, earth-abundant bifunctional catalysts for polyolefin hydrocracking.
- Unique site proximity and heteroatom compatibility of WxC address key challenges in chemical recycling of challenging polymer feedstocks.
- WxC catalysts present a promising platform for developing tailored solutions for specific polymer waste streams.
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