Recent Research Advancements in Catalytic Pyrolysis of Plastic Waste

Abstract

The disposal of plastic waste is currently one of the major global issues affecting environmental balance and mankind. It is therefore crucial to turn waste plastic into value-added products. Thermochemical recycling techniques have been researched extensively to generate fuels, monomers, and other value-added products. It has been determined that pyrolysis is an effective method for chemical recycling. Plastic wastes are transformed into products including liquid oil, gas, and solid residues during the thermal breakdown. Low-quality liquid oil and gaseous products are also produced through thermal pyrolysis, which demands a long retention period and high temperature. Catalytic pyrolysis helps to deal with these problems. To obtain higher quantities of fuel in the form of liquid or gas, varieties of catalysts, such as natural zeolite, Y-zeolite, HZSM-5, ZSM-5, FCC, mud, Ca(OH)2, Al2O3, and Fe2O3, are used. The present Perspective aims to briefly unveil the recent developments in the catalytic pyrolysis of plastic waste. It primarily focuses on the impact of catalytic pyrolysis on the yields and composition of products as well as their further applications. Also, an extensive review of techno-economic assessment based on capital and operating cost, utilization of coproducts, utilization as fuel, as well as feedstock logistics has been presented.

Critical issues for the deployment of plastic waste pyrolysis

“…Additionally, the techno-economic viability of catalytic pyrolysis of plastic waste has been demonstrated, provided that the plastic refuse prices remain low, especially for plants having high operational capacity. 16 Plastic cracking with acid catalysts follows a carbocationic mechanism. It usually proceeds in the initial reaction steps via carbenium ions produced by the abstraction of a hydride ion (Lewis acid sites) from the polymer or by the addition of a proton (Brønsted acid sites) to the polymer forming a carbonium ion.…”

“…Additionally, the techno-economic viability of catalytic pyrolysis of plastic waste has been demonstrated, provided that the plastic refuse prices remain low, especially for plants having high operational capacity. 16…”

“…Also the product composition was considered in view of process implementation at the industrial scale, 11,12 and the effect of the waste characteristics on the process efficiency 13 was a topic well exploited in the literature as well as the techno-economic assessment of the process. However, despite the fact that recent reviews have also summarized new trends in process development, [14][15][16] also from an engineering perspective, 17 there are still some critical issues that should be rationalized in view of commercial deployment of thermal and catalytic processes of plastic waste pyrolysis. Accordingly, with the particular perspective of future full development of the process at the industrial level and besides the evaluation of recent achievements in thermal and catalytic pyrolysis and co-pyrolysis, some of those open questions have been addressed in the present review.…”

Polyethylene Upgrading to Liquid Fuels Boosted by Atomic Ce Promoters

“…[2] Pyrolysis is one of the most conventional routes to this target, usually operated at 500-600 °C. [3] However, such harsh condition leads to enormous energy consumption and the rapid deactivation of catalysts. [4] As an alternative way, hydro-genolysis over monofunctional metal catalysts can take place at a relatively low temperature of 300 °C.…”

ACS Sustainable Chemistry & Engineering Virtual Special Issue: Thermal and Catalytical Chemical Conversions of Plastic Wastes for Sustainable Production of Energy, Fuels, and Chemicals

“…Chari et al 20 calculated the climate change impact of −371 kg CO 2 per ton of mixed plastic wastes processed by hydrogen production process. Mishra et al 21 systematically summarized the effect of different catalysts on product composition and yield when thermo-catalyzing waste plastics, starting from techno-economic evaluation, utilization of byproducts, utilization as fuel, and kinetic studies of feedstock pyrolysis. From their results, it can be found that a catalytic pyrolysis system for plastic wastes is indeed low cost, environmentally friendly, and efficient.…”