In situ ¹³C NMR monitoring of the dehydration of 2-propanol over H-ZSM-5

The first in situ ¹³C NMR monitoring of zeolite catalyzed reaction is described. The dehydration of 2-propanol over H-ZSM-5 was observed using solution type techniques. Although this produces broad lines, several mechanistic details were elucidated. This study indicates that: 1) the dehydration does not proceed through a cyclopropyl carbenium ion intermediate, 2) propene oligomerizes on the catalyst and reaches a steady state concentration before propene is desorbed, and 3) the 2-propanol flowing over the catalyst does not react with the oligomerized propene.