Synthesis, characterization and catalytic performances of Cu- and Mn-containing ordered mesoporous carbons for the selective catalytic reduction of NO with NH3

Abstract

A series of copper- and manganese-containing ordered mesoporous carbons (OMCs) were synthesized for the low-temperature selective catalytic reduction (SCR) of NO with NH₃. The results demonstrated that NO conversion can be greatly improved by the addition of Cu or Mn. In addition, Cu and Mn had a synergetic effect and the optimal catalytic performance was obtained over the bimetallic catalyst Cu5Mn5-OMC. N₂ sorption, small-angle X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm the ordered mesoporous structures. Wide-angle XRD results showed that in the bimetallic catalysts some Cu ions were substituted by Mn ions, resulting in lattice contraction by the formation of a solid solution. X-ray photoelectron spectroscopy (XPS) results indicated that the O–CO groups and chemisorbed oxygen species increased with the addition of Cu or Mn. Temperature-programmed desorption of CO/CO₂ and NH₃ (CO/CO₂-TPD and NH₃-TPD) results verified that the acidity of the catalyst was enhanced by the addition of Cu and Mn and the bimetallic catalyst Cu5Mn5-OMC had the strongest acidity. Temperature-programmed reduction of H₂ (H₂-TPR) results showed that Cu5Mn5-OMC had the strongest oxidizing capacity. Based on the above analysis, a possible synergetic catalytic effect was proposed through the electron transfer between Cu and Mn ions.