Manganese-containing VOC oxidation catalysts prepared in molten salts

Mn-Zr and Mn-Ti supported oxide catalysts have been prepared by means of reactions in molten Na(K)NO3 fluxes at 500 °C. The solids were characterized using X ray diffraction, textural measurements, optical spectroscopy and transmission electron microscopy. Highly dispersed ZrO2 and TiO2 covered with Mn(III, IV) species were obtained from the reaction in the melt. Due to the stabilizing effect of Mn, ZrO2-based solids with specific surface areas up to 220 m2/g were obtained. The influence of Mn loading and the nature of precursors on the solids properties were studied. The catalytic properties were studied in the model reactions of total oxidation of benzene and toluene. Molten salt derived solids demonstrated advantageous catalytic activity as compared to the reference catalysts. ZrO2-supported catalyst prepared using KMnO4 precursor showed the highest performance for the combustion of both aromatic hydrocarbons with T50 values of 236 and 167 °C for benzene and toluene oxidation, respectively.

One-pot reactions of MnCl2 or KMnO4 with Zr or Ti precursor salts in the NaNO3–KNO3 eutectic nitrate melts allow obtaining supported oxide catalysts containing Mn(III, IV) oxide species supported on TiO2 or ZrO2 nanoparticles. The solids as obtained possess advantageous textural properties and demonstrate high activity in the total oxidation of aromatics.Figure optionsDownload as PowerPoint slide