N-doped graphene and TiO2 supported manganese and cerium oxides on low-temperature selective catalytic reduction of NOx with NH3

Abstract

A series of N-doped graphene (NG) and TiO 2 supported MnO x -CeO 2 catalysts were prepared by a hydrothermal method. The catalysts with different molar ratios of Mn/Ce (6 : 1, 10 : 1, 15 : 1) were investigated for the low-temperature selective catalytic reduction (SCR) of NO x with NH 3 . The synthesized catalysts were characterized by HRTEM, SEM, XRD, BET, XPS, and NH 3 -TPD technologies. The characterization results indicated that manganese and cerium oxide particles dispersed on the surface of the TiO 2 -NG support uniformly, and that manganese and cerium oxides existed in different valences on the surface of the TiO 2 -NG support. At Mn element loading of 8 wt%, MnO x -CeO 2 (10 : 1)/TiO 2 -1%NG displayed superior activity and improved SO 2 resistance. On the basis of the catalyst characterization, excellent catalytic performance and SO 2 tolerance at low temperature were attributed to the high content of manganese with high oxidation valence, extensive oxidation of NO into NO 2 by CeO 2 and strong NO adsorption capacity, and electron transfer of N-doped graphene.

A Review of Low Temperature NH3-SCR for Removal of NOx

“…Given that the dispersion of two active components on support enhances the active sites further, researchers have been widely reported the supported binary transition metal-based oxides to improve the performance and SO 2 /H 2 O tolerance in NH 3 -SCR reaction. With this perspective, several composites, such as MnCe/CNTs [118], Mn-Fe/TiO 2 [119], MnO x -CeO 2 /graphene [120], Mg-MnO x /TiO 2 [121], CeO x -MnO x /TiO 2 -graphene [122], Fe-Mn/Al 2 O 3 [123], Mn-Fe/W-Ti [124], MnO x -CeO 2 /TiO 2 -1%NG (NG = N-doped grapheme) [125], Mn-Ce/CeAPSO-34 [126], etc., were investigated for the NH 3 -SCR reaction at low-temperature. Smirniotis et al [22] studied the promotional effect of co-doped metals (Cr, Fe, Co, Ni, Cu, Zn, Ce, and Zr) on the NH 3 -SCR performance of Mn/TiO 2 .…”

Addition of Ce in Cu/Three‐Dimensional Graphene Derived from Watermelon for Low Temperature NH3‐SCR

“…All the catalytic formulations exhibit primarily two peaks at 150 °C and 250–400 °C, which are attributed to NH 3 physically adsorbed on weak acid sites and medium strong acid sites respectively. As reported by Zhao, the NH 3 ‐TPD physisorption is too weak to activate NH 3 molecules, while the adsorbed NH 3 species on strong acid sites are hardly to desorb, which make not much contribution to low‐temperature NH 3 ‐SCR reaction . Hence, we focus on the discuss of the adsorption of NH 3 on medium‐strong acid sites.…”

A CAN-Based Urea Line Heater Diagnostics Development and Experimental Validation for Selective Catalytic Reduction (SCR) System

“…Wang and Lecompte et al researched specific catalyst performance by ice melting method under the low temperature SCR [12][13]. Zhao et al introduced a solution to reduce deposit of SCR system at low temperature [14][15][16]. There are many researchers who have made efforts to study solutions on heating system for SCR aftertreatment system, so as to make sure normal working status under low temperature such as engine cold start.…”