Reactions of 2-octanol on AmberlystA® 15: concurrent Eley-Rideal and Langmuir-Hinshelwood reactions on two different types of active sites

On Amberlyst(A (R)) 15 (dry) at 75 A degrees C, 2-octanol undergoes concurrent esterification and dehydration in the presence of heptanoic acid in the liquid phase. Kinetic data and O-18 labelling studies show that the esterification reaction most likely occurs by an Eley-Rideal (ER) mechanism between adsorbed carboxylic acid and bulk phase alcohol, while the dehydration reaction occurs by a Langmuir-Hinshelwood (LH) mechanism requiring interaction of adsorbed alcohol with a vacant site. The two reactions occur on two different types of catalytic sites: while all the sites are sulfonic acid groups, kinetic data suggest that not all of the acidic sites are positioned appropriately to a neighboring site to assist with dehydration. A kinetic model fits the observed data for the simultaneous ER and LH reactions over at least 23 h of observation.