Gold, vanadium and niobium containing MCM-41 materials—Catalytic properties in methanol oxidation

This work describes the syntheses, characterisation and catalytic application of silicate MCM-41 materials modified with gold, vanadium and niobium by their introduction during the synthesis (co-precipitation) performed with the use of HCl or H2SO4 as pH adjustment agent. The samples were characterised by XRD, N2 adsorption and test reactions (2-propanol and acetonylacetone transformations). Moreover, they were applied in the methanol oxidation, studied in the flow system and in situ FTIR method. It is shown that the basicity of AuMCM-41 is diminished by the introduction of transition metal species (V, Nb). The materials prepared by the use of H2SO4 (for the adjustment of pH) reveals a higher acidity, better ordering of mesopores, and a lower activity in methanol oxidation than those prepared with the use of HCl. The latter exhibit high activity in methanol oxidation to CO2. The presence of both, V and Nb, besides Au in MCM-41 makes the desorption of formaldehyde much easier increasing the selectivity.