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Plasma-assisted surface modification of silica supports and fully synthesized vanadium oxides was performed in a direct current hollow cathode discharge plasma sustained in $O_2$ gas. Operational plasma parameters, such as pressure, discharge power, and exposure time were also optimized to reach the highest possible plasma treatment effect. The modified catalysts were characterized using different techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Brunauer–Emmett–Teller, Fourier transform infrared, and inductively coupled plasma atomic emission spectroscopy. The results showed that the surface active sites of these catalysts were enhanced with the treatment of plasma, which improved the dispersion of the catalysts [1]. In addition, the average pore size was slightly enlarged, and the pore size distribution of the catalyst became wider. The XPS results revealed that the non-thermal plasma increased the oxygen functional groups on the catalyst’s surface, which contributed to their increasing activity [2]. Next, these active catalysts were introduced into a negative direct current multi-pin-to-plate glow discharge reactor generated in $N_2$/$O_2$ gas mixture in order to be used for $N_2$ oxidation. It was shown that the use of the catalyst resulted into the synthesis of $NO_x$ products. This study confirms that non-thermal plasma treatment is an effective tool to manipulate the catalyst surface properties for $N_2$ fixation processes.
[1] X. Zhang, W. Sun, C. Wei, Effect of glow discharge plasma treatment on the performance of Ni/$SiO_2$ catalyst in $CO_2$ methanation, Journal of Fuel Chemistry and Technology, 41 (2013) 96-101.
[2] C. Liu, J. Lan, F. Sun, Y. Zhang, J. Li, J. Hong, Promotion effects of plasma treatment on silica supports and catalyst precursors for cobalt Fischer–Tropsch catalysts, RSC Advances, 6 (2016) 57701-57708.
