Michael Stockenhuber

Catalytic cracking of high molecular weight hydrocarbons underpins the production of fossil fuels from petroleum vapour and the recycling of polyolefin waste plastic. However, thermal cracking over conventional microporous solid acids is hindered by poor mass‐transport. Here we explore the performance of hierarchical H−Y zeolites and Al‐SBA‐15 for the catalytic cracking of 1,3,5‐triisopropylbenzene (1,3,5‐TIPB) and low‐density polyethylene (LDPE) in a continuous fixed‐bed flow reactor. Dealumination by acid washing was used to create hierarchical mesoporosity in H−Y zeolite and modify the solid acidity. Physicochemical properties were studied by X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), gas adsorption, in‐situ Fourier transform infrared (FTIR), ex‐situ pyridine DRIFT, 29 Si and 27 Al nuclear magnetic resonance (NMR), and 1 H relaxation and pulsed field gradient (PFG) NMR diffusion studies. Despite weakening acidity, the introduction of hierarchical porosity promotes deep cracking of both feedstocks; HNO 3 dealuminated H−Y produces five times more cumene and benzene from 1,3‐5‐TIPB, and 33 % more benzene and xylenes from LDPE, than the parent H−Y.