Tailored Bronsted and Lewis acid sites of the phosphotungstic Wells-Dawson heteropoly-acid

SILVANA R. MATKOVIC; MARTA BOSCO; SEBASTIÁN E. COLLINS; LAURA E. BRIAND

Santa Fé

Simposio; IV San Luis School and Conference on Surfaces, Interfaces and Catalysis; 2018

Instituto de Desarrollo Tecnológico para la Industria Química INTEC

Previous investigations of the authors demonstrated the capability of the fosfotungtic Wells Dawson heteropoly-acid (HPA) H6P2W18O62 to catalyze the selective acylation of isobutylbenzene with acetic anhydride 1. The anhydride dissociatively chemisorbs on the Brønsted acid sites producing the intermediate acyl CH3CO+ species, adsorbed acetate species, and acetic acid. The former is known as the key intermediate species in the Friedel-Crafts acylation reaction. However, surface acetate species and acetic acid strongly adsorb on the active acid sites deactivating the heteropoly acid which prevented the further formation of p-isobutylacetophenone.Based on those observations, the present investigation is devoted to tune the acidity of the HPA in order to generate a material with both Lewis and Brønsted acid sites in order to overcome the problem of the irreversible adsorption of polar oxygenate species causing its deactivation.