EFFECTS OF CATALYST ACIDITY AND HZSM-5 CHANNEL VOLUME ON POLYPROPYLENE CRACKING

Effects of catalyst acidity and the restricted reaction volume afforde d by HZSM-5 on the catalytic cracking of polypropylene are described. Polypropylene cracking by silica-alumina and HZSM-5 catalysts yields o lefins as primary volatile products. In addition, HZSM-5 channels rest rict carbenium ion rearrangements and facilitate formation of signific ant amounts of propene and alkyl aromatic volatile products. The highe r acidity of sulfated zirconia compared to the other catalysts results in an increase in the frequency of hydride abstractions, resulting in the formation of significant yields of saturated hydrocarbons and org anic residue for this catalyst. Primary polypropylene cracking product s can be derived from carbenium ion reaction mechanisms. (C) 1998 John Wiley & Sons, Inc.