Evaluation of acid properties of mechanochemically synthesized supported niobium oxide catalysts in the alkylation of toluene

Niobium loaded SBA-15 aluminosilicates with different metal loadings (0.5 and 1 wt. %), were mechanochemically synthesized as catalysts for Friedel-Crafts alkylation reactions. The physicochemical properties of these materials were investigated by means of N-2 adsorption/desorption measurements, ICP-MS, DRIFT of Py-adsorption among other characterisation techniques. Niobium-loaded materials as well as their respective support displayed a mesoporous nature and the typical structure of SBA-15 materials. The impact of the incorporation of niobium on the aluminosilicate support on the acidic properties was investigated in the alkylation of toluene using benzyl alcohol and benzyl chloride as alkylating agents. The modification of SBA-15 aluminosilicates with Nb particles incorporated a low number of active sites shown to be highly active in alkylation reactions, reaching quantitative conversion in short reaction times (> 10 min), especially for the alkylation of toluene with benzyl chloride, catalysed by Lewis acid sites. The small increase in Lewis acid sites is going to lead to enhanced catalytic activities.