Review on Catalytic Depolymerization of Polyolefin Waste by Hydrogenolysis: State-of-the-Art and Outlook

Abstract

Mechanical recycling of plastic waste is not sustainable and inefficient in terms of the resources needed to accomplish the process, and the quality of the materials obtained from this technique is substandard. Chemical recycling of waste polymers appears to be preferable because this technology allows for the production of new materials. This review compiles the most recent research in which selected transition metals are used as catalysts for the hydrogenolytic depolymerization of waste polyolefins as a polymer upcycling process. Hydrogenolysis is an emerging chemical recycling method that uses transition-metal complexes as catalysts in the presence of hydrogen to cleave the C−C bonds of polymer substances into shorter hydrocarbons. Transition metals such as Ruthenium (Ru), Platinum (Pt), Nickel (Ni), Cobalt (Co), Zirconium (Zr), Tantalum (Ta), and Rhodium (Rh) have been utilized most recently for this type of reaction. This hydrogenolysis technique can produce valuable hydrocarbon products, such as gas/liquid fuels and lubricating oils, under relatively milder operational conditions and with less environmental impact. The review focused on the supported metal and organometal catalytic system and their mechanism for the polyolefin hydrogenolysis pathways and detailed investigation of the impact of reaction parameters on the production of high quality fuels such as gasoline, diesel, and light lubricants.

Perspectives on the Application of Waste Materials in Asphalt Based on Molecular Dynamics Simulations: A Review

“…Polyethylene terephthalate (PET) is usually used in making plastic products like water bottles, wrappings, and some fiber fabrics. , It is famous for its strength, transparency, and lightness . PET has good stability and is difficult to degrade, so it is the most common waste plastic …”

Industrial and Laboratory Technologies for the Chemical Recycling of Plastic Waste

“…Several state-of-the-art methods for the chemical recycling of PE use hydrogenolysis conditions to fragment the carbon backbone into gas, liquid fuels, and wax products with chain lengths ranging from C 1 to C 45 (Scheme B) . Heterogeneous transition metal catalysts based on Ru, Zr, Rh, Pt, and Co are typically employed at high temperatures and elevated pressures of hydrogen gas.…”

Chemical Upcycling of Polyolefin Plastics Using Structurally Well-defined Catalysts

“…Therefore, designing structurally well-defined catalysts is critical for the chemical upcycling of waste plastics as it helps to modulate both the polymer–active site and polymer–support interaction. There have been reviews on PO hydrogenolysis that summarize the recent developments in catalysts and catalytic processes. ,,− Some reviews also list catalysts with their compositions, catalysis conditions, and major products. ,,, Herein, we focus on interpreting the crucial roles of structurally well-defined catalysts at mesoscopic, nanoscopic, and atomic scales in advancing our fundamental understanding and improving the catalytic activity and selectivity of PO hydrogenolysis. We also give our perspective on designing and synthesizing structurally well-defined catalysts that could further improve their catalytic performance in PO hydrogenolysis.…”

“…There have been reviews on PO hydrogenolysis that summarize the recent developments in catalysts and catalytic processes. 16 , 22 , 24 − 27 Some reviews also list catalysts with their compositions, catalysis conditions, and major products. 10 , 24 , 26 , 27 Herein, we focus on interpreting the crucial roles of structurally well-defined catalysts at mesoscopic, nanoscopic, and atomic scales in advancing our fundamental understanding and improving the catalytic activity and selectivity of PO hydrogenolysis.…”

“… 16 , 22 , 24 − 27 Some reviews also list catalysts with their compositions, catalysis conditions, and major products. 10 , 24 , 26 , 27 Herein, we focus on interpreting the crucial roles of structurally well-defined catalysts at mesoscopic, nanoscopic, and atomic scales in advancing our fundamental understanding and improving the catalytic activity and selectivity of PO hydrogenolysis. We also give our perspective on designing and synthesizing structurally well-defined catalysts that could further improve their catalytic performance in PO hydrogenolysis.…”