Scientists crack plastic waste into fuel without chemicals or heat
Researchers have developed a catalyst that converts discarded plastic bags into gasoline-range fuel at just 260°C—without solvents, metals, or added hydrogen. The breakthrough could dramatically cheapen plastic recycling and turn waste streams into profitable products for refineries and chemical manufacturers.
Originaltitel: Solvent- and metal-free upcycling of low-density polyethylene using a practical ZSM-5/Al<sub>2</sub>O<sub>3</sub> bead catalyst
<p>Upcycling plastic waste into valuable resources without solvents, precious metals, or additional H<sub>2</sub> under mild conditions is a formidable challenge that requires new innovations. Herein, we document a catalyst based on Al<sub>2</sub>O<sub>3</sub> beads and zeolite ZSM-5 (ZSM-5#Al<sub>2</sub>O<sub>3</sub>(2 h)). It cracked polyethylene (PE) into gasoline-range C<sub>4</sub> − C<sub>12</sub> hydrocarbons with a selectivity of 98% and a yield of >71% within 1.5 h at 260 °C. Characterization of the catalysts revealed a mesoporous structure and suitable Brønsted acid sites, which promoted the diffusion and catalytic activation of PE. Adjusting the dosage of zeolite supported on Al<sub>2</sub>O<sub>3</sub> beads enables regulation of both the number and strength of acidic sites. Theoretical calculations confirmed that the interfacial interaction between zeolite ZSM-5 and Al<sub>2</sub>O<sub>3</sub> reduces the acid strength of the composite. This is beneficial for the formation of higher hydrocarbons. Remarkably, the process was performed in a 1 L CSTR unit. These results provide instructive guidance for the design of high-performance catalytic materials used in PE waste recycling.</p>