MnO_x–CeO_x Nanoparticles Supported on Porous Hexagonal Boron Nitride Nanoflakes for Selective Catalytic Reduction of Nitrogen Oxides

In selective catalytic reduction (SCR) technology, aggregation of the catalyst generally degrades the performance for converting nitrogen oxides into harmless gases. To avoid such performance degradation and to achieve a noticeable improvement in the SCR performance, good dispersion of the catalyst on the support is required. In this study, we synthesized MnOx–CeOx catalytic nanoparticles on surface-modified supports and studied the dispersion behavior of the catalyst on the support. Hexagonal boron nitride (h-BN) was adopted as the catalyst support, which was modified by catalytic etching to create vacancy defects on the support. To enhance the effect of surface modification, the etched h-BN flakes were exfoliated by ultrasonication treatment and were further modified by controlling the pH of the surface. As a consequence of surface modification, the specific surface area increased from 41.89 to 67.29 m2/g. Microscopic analysis revealed that the size of the catalytic particles was mainly distributed with an average of 5 nm in modified h-BN. Surprisingly, the conversion efficiency of NOx gas approached 97% at a relatively low temperature (175–225 °C) when surface-modified h-BN was used as the support. The noticeable improvement in the catalytic performance is attributed to the high dispersion of active materials with the use of a porous support.