Synthesis and catalytic performances of manganese oxides-loaded porous halloysite/carbon composites for the selective catalytic reduction of NO with NH 3

Self-made porous halloysite/carbon composite (HAL/C) was used as a novel catalyst carrier which was prepared using halloysite as template, chitosan as carbon source and potassium carbonate as activating agent via one-step carbonization-activation. Then the manganese oxides (MnOx) supported HAL/C catalyst was prepared by impregnation method. The influences of contents of Mn and carbon in catalyst on the low-temperature selective catalytic reduction of NO by NH 3 (NH 3 -SCR) were investigated. The Mn 12 -HAL/C-2 catalyst (mass ratio of chitosan to halloysite was 2 and Mn loading content was 12 wt%) exhibited the highest SCR performance, giving an NO conversion of 95–100% in the temperature range of 150–300 °C. For Mn 12 -HAL catalyst without carbon loading, the highest conversion of NO was 89% at 250 °C. Thus it could be inferred that the introduction of carbon could greatly improved low-temperature SCR performance. The addition of carbon contributed to a larger specific surface (1805 m 2 /g) for abundant oxygen-containing functional groups and weak acid sites for Mn 12 -HAL/C-2 catalyst which was favorable to adsorb more NH 3 and facilitated SCR reaction process. As the increase of carbon, the weight loss of catalysts increased at higher temperature and the catalytic activity was declined.