Mechanistic Understanding of Efficient Polyethylene Hydrocracking over Two‐Dimensional Platinum‐Anchored Tungsten Trioxide

Abstract

Chemical upcycling of polyethylene (PE) can convert plastic waste into valuable resources. However, engineering a catalyst that allows PE decomposition at low temperatures with high activity remains a significant challenge. Herein, we anchored 0.2 wt.% platinum (Pt) on defective two‐dimensional tungsten trioxide (2D WO3) nanosheets and achieved hydrocracking of high‐density polyethylene (HDPE) waste at 200–250 °C with a liquid fuel (C5–18) formation rate up to 1456 gproducts ⋅ gmetal species−1 ⋅ h−1. The reaction pathway over the bifunctional 2D Pt/WO3 is elucidated by quasi‐operando transmission infrared spectroscopy, where (I) well‐dispersed Pt immobilized on 2D WO3 nanosheets trigger the dissociation of hydrogen; (II) adsorption of PE and activation of C−C cleavage on WO3 are through the formation of C=O/C=C intermediates; (III) intermediates are converted to alkane products by the dissociated H. Our study directly illustrates the synergistic role of bifunctional Pt/WO3 catalyst in the hydrocracking of HDPE, paving the way for the development of high‐performance catalysts with optimized chemical and morphological properties.

Chemical Upcycling of Polylactic Acid Plastic Waste into Alanine over Ru/CeO2 with Decoration of Indium

“…Low-temperature EPR characterization was also tested and is shown in Figure . A typical signal with a g value of 2.003 was detected for Ru/CeO 2 and Ru/Ce 3 In-MMO catalysts, which confirmed the existence of oxygen vacancies . It was found that the intensity of Ru/Ce 3 In-MMO was apparently higher than that of Ru/CeO 2 , testifying that there were more oxygen vacancies in Ru/Ce 3 In-MMO, which was consistent with the results of the O 1s XPS spectra.…”

Layered Double Hydroxide Derivatives for Polyolefin Upcycling

“…Importantly, the absence of the C�O vibration (1720 cm −1 ) throughout the entire process indicates that the support does not function as an acid site. 53 Additionally, a progressively intensifying C�C vibration at 1630 cm −1 is observed, suggesting the formation of olefin intermediates during the catalytic process. These findings, coupled with the analysis of liquid products via GC spectrum (Figure S21), which excludes a hydrocracking mechanism (metal-acid synergistic catalysis), lead to the conclusion that the conversion process follows a hydrogenolysis mechanism (metal catalysis).…”

“…This signifies the ongoing conversion of n -butane into methane. Importantly, the absence of the CO vibration (1720 cm –1 ) throughout the entire process indicates that the support does not function as an acid site . Additionally, a progressively intensifying CC vibration at 1630 cm –1 is observed, suggesting the formation of olefin intermediates during the catalytic process.…”

Catalytic Strategies for the Upcycling of Polyolefin Plastic Waste

“…With more insight into the C–C cleavage over the supported Pt nanoparticle surface, it is usually regarded that the polyethylene adsorption occurred on the Pt nanoparticles rather than the oxide matrix. − Celik et al studied the adsorption site for hydrocarbons theoretically and experimentally . They calculated the adsorption energies for the interaction of model n -alkanes (C n H 2 n +2 , where n = 4, 6, and 8) onto Pt(100) and Pt(111) surface models as representations of the Pt nanoparticles as well as the TiO 2 double layer to simulate the oxide surface.…”

“…Unlike direct high-temperature catalytic pyrolysis, catalytic hydrogenation realized the depolymerization of polyolefins or polyesters by breaking carbon–carbon or carbon–oxygen bonds at lower temperatures. − Because the final product of hydrogen is water or a part of hydrocarbons, the entire reaction process is thermodynamically favorable. Additionally, the mild reaction conditions allow for flexible adjustment of product selectivity through the design of the catalyst structure over a wide range, which significantly outperforms high-temperature catalytic cracking.…”