Comparison of Physicochemical Properties and Catalytic Activity in the m-Xylene Isomerization of Catalysts Based on ZSM-12 Zeolites Prepared at Hydrothermal Conditions and under the Action of Microwave Radiation

The properties of ZSM-12 zeolites prepared under hydrothermal conditions and microwave radiation influence were studied. The prepared zeolites are characterized by a wide range of physicochemical methods of analysis: X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, scanning electron microscopy, solid-state 27Al and 29Si NMR spectroscopy, infrared spectroscopy, temperature-programmed desorption of ammonia, infrared spectroscopy of adsorbed pyridine, and X-ray fluorescence elemental analysis. The calcined zeolites were impregnated with 0.5 wt % Pt, which performs the hydrogenation function in the reaction under study. The obtained materials were studied in the m-xylene isomerization reaction under the following conditions: Т = 300–440°С, WHSV = 1 h–1, Р(Н2) = 10 atm. It was found that, on the ZSM-12 MW catalyst, owing to its high acidity and fine particles, which promote high mass transfer, it is possible to increase the yields of m-xylene isomers, in particular p-xylene, to 36–65%.