Mesoporous manganese oxides for NO2 assisted catalytic soot oxidation

Abstract

Air pollution issues due to soot/diesel particulate matter (DPM) emitted from incomplete burning of diesel fuel have become a global issue in this century. A series of manganese oxides, namely amorphous manganese oxide (Meso-Mn-A), Mn2O3 (Meso-Mn2O3), MnO2 (epsilon phase) (Meso-ϵ-MnO2) and octahedral molecular sieves MnO2 (Meso-OMS-2) was synthesized via a soft template method. The potential of mesoporous manganese oxides in acceleration of NO2 assisted catalytic oxidation of diesel soot (Printex-U) under lean conditions was investigated. The physiochemical properties of synthesized materials were systematically characterized by X-ray diffraction, N2-sorption, high-resolution transmission electron microscopy, and H2-temperature programmed reduction. A series of temperature programmed oxidation experiments was carried out to investigate the effect of feed gas composition on activity of the catalyst, and TGA-MS experiments were done to calculate the kinetic energy for each system. Mesoporous manganese oxides were found to be effective for complete oxidation of diesel soot under exhaust gas temperatures, and activities of all the manganese oxides were increased in the presence of NO2 in the feed gas. Meso-ϵ-MnO2 possesses the highest performance, exhibiting the lowest Ti and Tm (230 °C and 305 °C), the narrowest temperature range (75 °C), and the lowest Ea (298 kJ/mol).

Metal organic frameworks as precursors for the manufacture of advanced catalytic materials

“…Due to their unique redox properties, low cost, and environment compatibility, manganese oxides are well known candidates for numerous catalytic applications 137 including decomposition of hydrogen peroxide, partial oxidation with hydrogen peroxide, oxidation of CO, methane, aromatic compounds, aqueous phenol in aqueous solution, NO-CO reaction, and chemical-looping combustion processes. 138 The only MOF derived Mn based catalyst reported so far in the literature appears in the work carried out by Peng et al 139 These authors developed a novel methodology for the formation of large-pore mesoporous mixed valence Mn 3 O 4 via the conversion of a Mn-MOF fabricated in ionic liquid (IL)-water mixtures for the degradation of MB.…”

Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts

“…They have been studied for the catalytic oxidation of soot from the exhaust stream of diesel vehicles and also as a catalyst support in the catalytic oxidation of NO [1]. They have also been widely studied for the oxidation of CO and VOCs which are other typical species emitted form mobile combustion engines [1,12,13,18,28,36,37]. Octahedral molecular sieves (OMS) are a crystalline form of manganese oxide.…”

3DOM SiO2-Supported Different Alkali Metals-Modified MnOx Catalysts: Preparation and Catalytic Performance for Soot combustion

“…Besides for improving the contact condition, people also do a lot of work on enhancing the intrinsic activity of catalysts. Many catalysts, which including noble metals, perovskite‐type oxides, CeO 2 ‐based oxides, MnOx‐based oxides etc, have been designed and studied for soot combustion . In the past decades, owing to changing valence states of Mn 4+ , Mn 3+ and Mn 2+ in the MnO x , manganese oxides exhibit excellent catalytic performance for redox reactions.…”