Gas-phase synthesis of aromatic ketones by acylation of phenol with acetic acid

C. PADRÓ AND C.R. APESTEGUÍA

JOURNAL OF CATALYSIS

Elsevier

Año: 2004 vol. 226 p. 308 - 320

0021-9517

The gas-phase synthesis of aromatic ketones via acylation of phenol with acetic acid was studied on SiO2-Al2O3, Al-MCM-41, zeolites HY and ZSM5, and tungstophosporic acid (HPA) supported on MCM-41 and Carbon. At contact times of 146 g h/mol, the initial conversion of phenol varied between 12.5% (HY) and 19.1% (HPA/MCM-41), and the initial selectivity to orto-hydroxyacetophenone (o-HAP) between 37.1 % (HPA/C) and 69.1% (HY).  In all the cases, the formation of o-HAP was clearly favored in comparison to that of para-isomer.  Zeolites HY and ZSM5, which contained a balanced concentration of strong Brönsted and Lewis acid sites, produced efficiently o-HAP via both the direct C-acylation of phenol and the acylation of phenyl acetate intermediate formed from O-acylation of phenol.  HPA-based catalysts contained only Brönsted acid sites and formed o-HAP exclusively as a secondary product from phenyl acetate.  The o-HAP yield remained constant with time on stream on ZSM5 but drastically decreased on the other samples because of coke formation.  The superior stability of zeolite ZSM5 was interpreted by considering that coke precursors formation is avoided into the microporous structure of this zeolite.