Kinetic Modeling of Phenol Acylation with Acetic Acid on HZSM5

We have developed a kinetic model that quantitatively describes the formation of the main products of phenol acylation with acetic acid (AA) on HZSM5 at 280°C, namely, phenylacetate (PA), o- and p-hydroxyacetophenones (o-HAP and p-HAP, respectively), p-acetoxyacetophenone (p-AXAP), and water. Analyses of the experimental data and kinetic modeling results lead to the following conclusions. Formation of PA occurs rapidly via O-acylation of phenol with acetic acid. o-HAP is produced via C-acylation of phenol with AA and PA. The latter reaction is responsible for the formation of about 90% of o-HAP. A part of p-HAP is produced via acylation of phenol with PA, the other one through hydrolysis of p-AXAP resulting from the autoacylation of PA. Kinetic modeling of phenol acylation with acetic acid shows that the maximum possible selectivity and yield of the desired product (o-HAP) can be obtained with P+AA mixtures with a low P/AA ratio