Kinetic evidence for two different active sites on dry Amberlyst® 15 catalyst in the alkylation between 1-dodecene and p-xylene

On Amberlyst((R)) 15 catalyst (dry) at 85 degrees C, 1-dodecene underwent concurrent double bond isomerization and alkylation with p-xylene. The alkylation reaction appeared to occur by an Eley-Rideal mechanism in which adsorbed olefin reacted with bulk phase p-xylene. Kinetic data showed that alkylation was irreversible and that the intermediate complex between olefin and p-xylene underwent isomerization in which the aromatic ring moved between adjacent carbons on the dodecyl chain. Given enough reaction time, the dodecyl p-xylene isomers always reached the same equilibrium distribution, regardless of catalyst loading. Kinetic modeling of concurrent olefin isomerization and alkylation showed that these two reactions must occur on two different catalytic sites. Alkylation was inhibited by the formation of dodecyl p-xylenes, while double bond isomerization was not.