Catalytic conversion of polyolefins into fuels over zeolite beta

The catalytic degradation of polypropylene and both low- and high-density p olyethylene over different samples of zeolite beta has been investigated. Z eolite beta synthesized by the fluoride method has a low activity for the c racking of polyolefins, which is related to its large crystal size (12 mu m ) and poor aluminium incorporation. In contrast, zeolite beta synthesized f rom amorphous xerogels consists of small crystallites (less than or equal t o 200 Mm) and allows all the polyolefins to be degraded with high conversio n (40-60%) and good selectivity towards C-5-C-12 hydrocarbons (60-70%), hea vier products being hardly obtained (< 6%). The incorporation of titanium i nto the BEA structure has been proved to enhance the catalytic activity, as denoted by the highest conversion per Al atom obtained with the Ti-Al-beta sample compared to Al-beta. (C) 2000 Elsevier Science Ltd. All rights rese rved.