Study on the direct introduction of titanium and niobium into silica-pillared magadiite

Abstract

Transition metal-containing solids have been extensively studied due to the various properties that metals can offer in catalysis, electrochemical, and adsorption processes. Titanium-containing silicates have been investigated as catalysts for oxidation reactions. Despite receiving minimal attention, niobium-containing silicates show significant potential for catalyzing reactions involving biomass. In this study, titanium and novel niobium-containing pillared magadiites were obtained by a single route, with modifications achieved using pillaring sols from different metal sources, including alkoxides and oxalate. The influence of hydrolysis stabilization of the alkoxide sources was also evaluated. The resulting transition metal-containing magadiites exhibited Ti and Nb sites with distinct coordination environments on the surface and in the bulk regions. Textural properties were altered based on the metal source used in the pillaring sol. The results suggested that titanium was better incorporated through pre-stabilization, considering water and alkali content. In reverse, the metal sites on the surface seem linked to non-typical tetrahedral titanium in titanosilicates. Niobium was better incorporated when the precursor was directly introduced into the pillaring sols and presented surface sites when the Nb source was not reacted before being added to the pillaring sol. The obtained materials have the potential to be applied in the catalytic transformation of bulky molecules.