Ultralow specific surface area vermiculite supporting Mn-Ce-Fe mixed oxides as “curling catalysts” for selective catalytic reduction of NO with NH3
Yinji Wan, Junqi Tian, Gang Qian, Zhisong Liu, Wenjian Li, Jianming Dan, Bin Dai, Feng Yu
Abstract
In this study, the ultralow specific surface area clay vermiculite (VMT) was selected to be a catalyst support for the NH3-SCR process, and the active components MnCeFeOx loaded on vermiculite was just like curling on ice from the TEM results. The de-NOx performance of Mn–Ce–Fe/VMT exhibited almost complete NO conversion with a gas hourly space velocity (GHSV) of 15,300 h−1 at 150 °C, which was 25% and 10% higher than that of Mn/VMT and Mn–Ce/VMT, respectively. Ce and Fe co-doping improved the BET surface area, the quantities of active Mn4+, the acid sites and NH3 adsorption energy of Mn/VMT, all of which contributed to the increase in low-temperature SCR activity. In situ DRIFT measurements suggested that NOx removal over Mn–Ce–Fe/VMT followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms at 150 °C, but the E-R mechanism played a dominant role. Corresponding Mn–Ce–Fe/VMT monolithic catalysts reached 90% NO conversion with a GHSV of 4000 h-1.