CATALYTIC CRACKING OF LINEAR PARAFFINS - EFFECTS OF CHAIN-LENGTH

The influence of chain length on cracking reactions of linear paraffin s on acid catalysts has been examined. Whether studied as individual r eactants, as components of simple mixtures of paraffins, or as minor c onstituents of complex industrial FCCU feedstocks, increasing chain le ngth of n-paraffins is associated with increasing cracking reactivity. This increase in reactivity cannot be accounted for solely by conside ring the increase in the number of carbon atoms or the number of crack able bonds in the molecular structure. However, by simultaneously taki ng into account adsorption phenomena and crackable bonds, good correla tions between observed rates and predicted behavior are obtained, both for cracking of individual paraffins and for components of simple par affin mixtures. Reasonable correlations are also observed for cracking rates of linear paraffins as components of industrial FCCU feedstocks . The presence of other components in the feed can influence the crack ability of linear paraffins but does not have a major influence on the relative cracking rates of linear paraffins due to chain-length effec ts.