Catalytic Hydrogenolysis of Polyethylene Under Reactive Separation

Deconstruction of polyolefins by catalytic hydrogenolysis is typically accompanied by the generation of undesired light gases. At reaction temperatures, the desired liquid products also tend to be volatile. Secondary cleavage of these liquid products contributes to light gas formation. The latter process was mitigated by reactive separation, continuously separating the liquid products from the catalyst throughout the experiment. At equivalent conversion, the yield and selectivity for oligomeric liquid species are increased under reactive separation, even though the carbon-carbon bond cleavage rate is slower than that in sealed experiments. More light gas is formed in the sealed reactor. Under 1 atm H-2 partial pressure, alkenes accompany the typical alkane hydrogenolysis products. The alkene yield is higher, with greater selectivity for valuable alpha-olefins under reactive separation. These results provide the mechanistic insight that terminal alkenes are primary products of carbon-carbon bond cleavage during hydrogenolysis under experimental conditions, and secondary deconstruction of these species produces light gases.