Polyethylene Upgrading to Liquid Fuels Boosted by Atomic Ce Promoters

Abstract

Hydrocracking catalysis is a key route to plastic waste upgrading, but the acid site‐driven C‐C cleavage step is relatively sluggish in conventional bifunctional catalysts, dramatically effecting the overall efficiency. We demonstrate here a facile and efficient way to boost the reactivity of acid sites by introducing Ce promoters into Pt/HY catalysts, thus achieving a better metal‐acid balance. Remarkably, 100 % of LDPE can be converted with 80.9 % selectivity of liquid fuels over the obtained Pt/5Ce‐HY catalysts at 300 °C in 2 h. For comparison, Pt/HY only gives 38.8% of LDPE conversion with 21.3% selectivity of liquid fuels. Through multiple experimental studies on the structure‐performance relationship, the Ce species occupied in the supercage are identified as the actual active sites, which possess remarkably‐improved adsorption capability towards short‐chain intermediates.

Copolymerization of Olefins and Conjugated Dienes: A Promising Approach to Produce Recyclable Polyolefins

“…Recently, a diverse range of polyolefin upcycling techniques have been developed, including pyrolysis, 5,36,37 hydrogenolysis, 38−42 tandem hydrogenolysis-aromatization, 43 alkane metathesis, 44−49 and hydrocracking. 50 Among them, the incorporation of more chemically reactive functional groups into the polyolefin main chains to facilitate degradation has gained increasing attention. 51,52 The ultimate goal of these efforts is to explore "polyolefin-like materials" which can mitigate negative impacts on the environment, but preserve the benefits of polyolefins.…”

“…Nevertheless, their high cost, poor hydrolysis resistance, etc., partly limit the broad replacement for polyolefins. Recently, a diverse range of polyolefin upcycling techniques have been developed, including pyrolysis, ,, hydrogenolysis, − tandem hydrogenolysis-aromatization, alkane metathesis, − and hydrocracking . Among them, the incorporation of more chemically reactive functional groups into the polyolefin main chains to facilitate degradation has gained increasing attention. , The ultimate goal of these efforts is to explore “polyolefin-like materials” which can mitigate negative impacts on the environment, but preserve the benefits of polyolefins. ,− Insertion of ketones into PE through the copolymerization of ethylene with carbon monoxide results in photodegradable PE derivatives that can decompose to smaller fragments but falls short of closed loop recycling .…”