Polyethylene Catalytic Hydrocracking by PtHZSM-5, PtHY, and PtHMCM-41

Abstract

The mechanisms involved in polyethylene catalytic hydrocracking are investigated by monitoring temperature-dependent evolution profiles derived from mass spectra obtained while polymer/catalyst samples were heated at a constant rate. Repetitive injection gas chromatography/mass spectrometry (GC/MS) results are used to identify class-specific fragment ions that represent paraffins, olefins, and alkyl aromatics. Class-specific ion signals are used to generate isoconversion-effective activation energy plots from which mechanistic comparisons are made. Studies using PtHZSM-5, PtHY, and PtHMCM-41 bifunctional solid acid catalysts in helium and hydrogen are reported. The effects of hydrogen on polyethylene cracking are dramatic and result in significant changes to isoconversioneffective activation energies. Catalytic cracking mechanisms for the three catalysts are compared and differences are explained by a combination of pore size and acidity effects. © 2004 Wiley Periodicals, Inc.