Mesoporous SBA-15 promoted by 3d-transition and noble metals for catalytic combustion of acetonitrile

• Combustion of very toxic CH3CN by diverse catalysts was investigated.
• Combustion mechanism related to N2, or N2O, or NH3, or NO formation was proposed.
• Catalytic behaviors were correlated well with the chemical natures of catalysts.
• Cu/SBA-15 exhibited a satisfactory CH3CN conversion and the best N2 selectivity.

A series of M/SBA-15 [M = 3d transition metals (Cu, Co, Fe, V, Mn) and noble metals (Pd, Ag, Pt)] catalysts was prepared via an impregnation method, and further characterized by XRD, N2 physical adsorption, TEM, H2-TPR and XPS as well as activity test for CH3CN + O2 reaction. Ordered mesoporous structure of SBA-15 was well maintained even after impregnating the various metallic components. The CH3CN conversion of the investigated catalysts follows a trend of Pt/ > Pd/ > Cu/ > Co/ > Fe/ > V/ > Ag/ > Mn/ > SBA-15. Apart from the target product of N2, harmful byproducts (NO, NO2, N2O, NH3 and CO) were also observed during the catalytic combustion. The corresponding activities and selectivities were verified to be associative with both redox properties and chemical natures of the loaded metals. Among the prepared M/SBA-15 samples, Cu/SBA-15 exhibited a nearly complete CH3CN conversion associated with a N2 selectivity around 80% at T > 350 °C, being regarded as a promising material for the catalytic removal of nitrile gases. Moreover, the activities of the Cu supported on different substrates (SBA-15, Al2O3, and SiO2) were comparatively investigated and with the results indicating that SBA-15 is the proper candidate as a support for copper. Furthermore, the CH3CN catalytic combustion mechanism was studied by DRIFTS. Four kinds of mechanisms were proposed to be essentially dependent on the physicochemical nature of the loaded metals and their supports, as well as the reaction temperature, with a priority formation of N2 or NH3 or N2O or NO, respectively.

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