Effect of Calcination Conditions on MnOx/Al2O3 Catalytic Efficiency for NO Oxidation

Abstract

Calcination conditions in the catalyst preparation process have a significant influence on catalyst performance. To explore the optimal calcination condition of ${\mathrm{MnO}}_x/{\mathrm{Al}}_2{\mathrm{O}}_3$ catalysts for NO oxidation, a series of samples was prepared using the same support and active compound but under different calcination conditions. The catalytic efficiency of the catalyst was tested, and through characterization [X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE SEM), Brunauer–Emmett–Teller analysis (BET), and Barrett–Joyner–Halenda analysis (BJH)], the effect of calcination conditions on the catalytic performance was analyzed and discussed. The results showed that the samples calcined at 600°C for 5 h had the best catalytic performance. At a reaction temperature of 450°C, the molar ratio of ${\mathrm{NO}}_2/\mathrm{NO}$ conversion was as much as 1.65. The high surface area, crystal phase, and crystallinity (the relative content of ${\mathrm{Mn}}_2{\mathrm{O}}_3$ is about 50%); the high content of lattice oxygen ${\mathrm{O}}_{\beta }$ (about 20.4%); and high dispersion of active sites on the ${\mathrm{MnO}}_x/{\mathrm{Al}}_2{\mathrm{O}}_3$ catalyst calcined at 600°C for 5 h led to its relatively high catalytic activity. Compared with traditional noble metal catalysts, the ${\mathrm{MnO}}_x/{\mathrm{Al}}_2{\mathrm{O}}_3$ catalyst prepared by the impregnation method has good application prospects because of its low material cost, simple preparation process, and superior catalytic performance.