Abstract
Development of facile approaches to convert plastic waste into liquid fuels under neat conditions is highly desired but challenging, particularly without noble metal catalysts and an external hydrogen source. Herein, highly efficient and selective polyethylene-to-gasoline oil (branched C6–C12 alkanes) conversion was achieved under mild conditions (<170 °C) using commercially available AlCl3-containing molten salts as reaction media and to provide catalytic sites (no extra solvents, additives, or hydrogen feeding). The high catalytic efficiency and selectivity was ensured by the abundant active Al sites with strong Lewis acidity (comparable to the Al type in acidic zeolite) and highly ionic nature of the molten salts to stabilize the carbenium intermediates. Dynamic genesis of the Al sites was elucidated via time-resolved Al K-edge soft X-ray and 27Al NMR, confirming the tricoordinated Al3+ as active sites and its coordination with the as-generated alkene/aromatic intermediates. The carbenium formation and polyethylene chain variation was illustrated by inelastic neutron scattering (INS) and an isotope-labeling experiment. Theoretical simulations further demonstrated the successive hydride abstraction, β-scission, isomerization, and internal hydrogen transfer reaction pathway with AlCl3 as active sites. This facile catalytic system can further achieve the conversion of robust, densely assembled, and high molecular weight plastic model compounds to liquid alkane products in the diesel range.
| Original language | English |
|---|---|
| Pages (from-to) | 16207-16216 |
| Number of pages | 10 |
| Journal | Journal of the American Chemical Society |
| Volume | 147 |
| Issue number | 19 |
| DOIs | |
| State | Published - May 14 2025 |
Funding
The research was supported financially by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The GC-MS spectra was performed by F.P., who was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science program. Neutron scattering experiments were conducted at the VISION beamline at ORNL’s Spallation Neutron Source, which is supported by the Scientific User Facilities Division, Office of Basic Energy Sciences (BES), U.S. Department of Energy (DOE), under Contract No. DE-AC0500OR22725 with UT Battelle, LLC. XRD was performed at the Institute for Advanced Materials & Manufacturing (IAMM) Diffraction Facility, located at the University of Tennessee, Knoxville. NMR data were collected at the NMR Core Facilities of the University of Tennessee Knoxville. Quantum Chemistry calculations were performed at the Center for Nanophase Materials Sciences, a US Department of Energy Office of Science User Facility operated at Oak Ridge National Laboratory. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231.