Metathesis, molecular redistribution of alkanes, and the chemical upgrading of low-density polyethylene

A new strategy for polyethylene (PE) deconstruction via alkane metathesis is presented, in which WOx/SiO2 catalyzes the olefin metathesis reaction step. Zeolite 4 A is an essential component to protect the metathesis active sites from poisoning by in-situ-generated oxygenates in a batch reaction system. High conversion of 1-hexadecene (96%) and n-hexadecane (92%)—surrogates of long-chain molecules—demonstrates the high reactivity of WOx/SiO2 metathesis catalyst for olefin and alkane metathesis reactions, respectively, at moderate reaction temperatures of 300 °C for 2–3 h. Pretreatment temperature and length of the short n-alkane-chain solvent significantly affect the metathesis reactivity and selectivity. Results for the deconstruction of low-density PE (LDPE) in n-decane demonstrate a remarkable potential for PE upgrading with the advantages of short reaction times (3 h), the low mass ratio of solvent to LDPE, and the production of solid products with narrow molecular weight distributions. [Display omitted] •Supported tungsten oxide (WOx/SiO2) is shown to be an effective metathesis catalyst for the molecular redistribution of olefin/alkane feedstocks.•Addition of zeolite 4 A is essential to achieve high yields in olefin and alkane metathesis reactions.•Pretreatment temperature and chain length of alkane solvent have significant effects on catalytic conversion and selectivity.•Catalytic molecular redistribution of n-alkanes is a useful reaction in the chemical upgrading of polyethylene.