Effects of catalyst acidity and the restricted reaction volume afforded by HZSM-5 on the catalytic cracking of polypropylene are described. Polypropylene cracking by silica-alumina and HZSM-5 catalysts yields olefins as primary volatile products. In addition, HZSM-5 channels restrict carbenium ion rearrangements and facilitate formation of significant amounts of propene and alkyl aromatic volatile products. The higher 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 organic residue for this catalyst. Primary polypropylene cracking products can be derived from carbenium ion reaction mechanisms.

Effects of catalyst acidity and the restricted reaction volume afforded by HZSM-5 on the catalytic cracking of polypropylene are described. Polypropylene cracking by silica-alumina and HZSM-5 catalysts yields olefins as primary volatile products. In addition, HZSM-5 channels restrict carbenium ion rearrangements and facilitate formation of significant amounts of propene and alkyl aromatic volatile products. The higher 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 organic residue for this catalyst. Primary polypropylene cracking products can be derived from carbenium ion reaction mechanisms.

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An interface and gas chromatograph oven are described that couple a thermogravimetric analyzer with a mass spectrometer and permit multiple capillary gas chromatographic separations of volatile thermal decomposition products generated during a single thermogravimetric analysis. Examples of the use of this apparatus for identifying the volatile products generated during poly(vinyl butyral) thermal decomposition in the presence of γ-alumina and catalytic cracking of poly(styrene) and poly(ethylene) are described. TG-GC/MS analyses employing isothermal, temperature programmed, and subambient temperature ramp gas chromatography separations are described. The apparatus permits repetitive temperature-programmed capillary gas chromatographic analyses of thermogravimetric effluent containing more than 25 constituents in 3-min intervals.