Catalytic cascade upcycling single-use natural rubber glove wastes into fuels via a two-stage pressurized fixed-bed reactor

Chemical upcycling rubber wastes into hydrocarbon fuels offers a promising approach toward achieving carbon neutrality . To generate fuel-range cycloalkanes and isoalkanes from natural rubber glove wastes (NRGWs), the depolymerization of NRGWs was performed by integrating hydropyrolysis with vapor-phase hydrogenation over a bifunctional Ni/Al 2 O 3 -SiO 2 catalyst. Isoprene and limonene were the primary alkenes obtained from the non-catalytic hydropyrolysis of NRGWs, and these intermediates were vapor-phase hydrotreated over Ni/Al 2 O 3 -SiO 2 producing C 10 cycloalkane as the dominant fuel-range products. Complete hydrogenation of isoprene and limonene was achieved under a catalyst to feedstock mass ratio of 2.0, giving a maximum gasoline yield of 92 wt% under 225 °C hydrogenation temperature at 0.2 MPa H 2 . A low hydropyrolysis temperature of 450 °C maximized C 10 cycloalkane yield at 72.3 wt% with 80.1% selectivity, while a high temperature of 600 °C yielded 76.6 wt% C 5 isoalkane. A deconstruction mechanism in the catalytic cascade upcycling of NRGWs was proposed by employing limonene hydrogenation as a probe reaction. The results demonstrate that upcycling polymer wastes by cascade hydropyrolysis‑hydrogenation is a promising approach to produce alternative fuels with improved properties.