High-Performance Mn-Al-O Catalyst on Reticulated Foam Materials for Environmentally Friendly Catalytic Combustion

Abstract

<p>MnO_x supported on alumina and La₂O₃-modified alumina have been prepared and characterized as methane combustion catalysts. X-ray diffraction (XRD) analysis has revealed the significant low-temperature interaction between MnOx and alumina, resulting in a solid solution Mn-La-γ*-Al₂O₃ and a hexaaluminate formation upon thermal treatment at 900-1000 °C and 1300 °C, respectively. Mn-Al-O and Mn-La-Al-O catalysts washcoated on highly porous reticulated foam materials (RFM) have been prepared by two methods, such as: 1) a wet impregnation of a washcoating alumina layer on RFM by Mn and La nitrate solutions, 2) a dip coating of RFM into Mn-La-Al-containing suspension. The chemical compositions of RFM were cordierite, Ni, and NiCr-alloy. The catalytic activity of washcoated RFM in the methane combustion has been compared with one of granulated catalysts. The influence of alumina form (γ-Al₂O₃, (γ+χ)-Al₂O₃, α-Al₂O₃), manganese loading (5 and 10 wt.%), modifying agent (La₂O₃) on catalytic activity have been studied. Catalytic performances of Mn-Al-O and Mn-La-Al-O catalysts washcoated on RFM and pretreated in methane-containing atmosphere at 1100 ºC have been investigated. The Mn-Al-O catalyst modified by La₂O₃ and supported on RFM have been tested in a prototype catalytic water heating boiler and demonstrated a considerable reduction in the emissions of NOx and CO compared to the conventional household boilers. The washcoating of the Mn-La-Al-O catalyst over surface of RFM provides a substantial reduction of toxic emissions during the catalytic fuel combustion. While an optimal foam structure and composition of the RFM provide improved heat and mass transfer properties of the catalyst in fuel combustion.</p>