Selective Hydrogenolysis Conversion of Polyethylene into Alkyl Oil Over Iridium-based Catalyst

Plastic not only brings convenience but also places a great burden on the environment. Utilizing plastic as a low-cost feed-stock for producing valuable chemicals and fuels is one of the most attractive directions. Among the huge types of plastics, polyolefins (PO), especially polyethylene (PE), were the most abundant type and the most difficult to upgrade. Hydrocracking and hydrogenolysis operate at relatively low reaction temperatures which show promising applications. Herein, Iridium-based catalysts were developed and proved to be effective in PE hydrogenolysis under relatively mild conditions. Catalysts were characterized by TEM, HRTEM, SEM, HAADF-STEM, XPS, CO chemisorption and H₂ chemisorption etc. The Ir catalysts showed similar reactivity but better selectivity for liquid products than Ru under similar conditions. A highest 92.7 % percent of liquid products could be obtained under 250 °C, 3 MPa of H₂ in 8 hours with Ir/γ-Al₂O₃ catalyst. The support could also affect the performance, including Lewis acid amount, surface areas, and morphology. And we suppose Iridium catalysts could serve as another choice for plastic hydrogenolysis under mild conditions.