Evaluation of strong acid properties of layered HNbMoO6 and catalytic activity for Friedel–Crafts alkylation

The acid properties and catalytic activity of layered HNbMoO6 for liquid-phase Friedel–Crafts alkylation are examined. 31P MAS NMR spectroscopy using trimethylphosphine oxide as a probe molecule reveals that HNbMoO6 possesses strong acid sites in the interlayer region. Layered HNbMoO6 is demonstrated to display remarkable catalytic performance for this reaction, substantially exceeding the activities of niobic acid, niobium–molybdenum mixed oxide, ion-exchange resins, and zeolites. It is determined that benzyl alcohol is intercalated into the HNbMoO6 interlayer during alkylation to form a monolayer configuration, allowing the strong interlayer acid sites to participate in the reaction.