Doping Manganese Oxides with Ceria and Ceria Zirconia Using a One-Pot Sol–Gel Method for Low Temperature Diesel Oxidation Catalysts
Ruairi O’Donnell, Kathryn Ralphs, Maxime Grolleau, Haresh Manyar, Nancy Artioli
Abstract
Abstract Octahedral molecular sieves (OMS-2) are an interesting form of manganese oxide with a 2 × 2 edge sharing tunnel structure and a cation positioned inside. Cryptomelane is an OMS-2 material with K + cations within the crystalline tunnel and has been widely used in catalytic oxidation reactions, due to a mixed valency of Mn 3+ and Mn 4+ cations. Cryptomelane (K-OMS-2) can be modified by structural incorporation of various dopants and tunnel cations which can enhance the catalytic activity of the material. It also offers to be a promising alternative material for the low temperature emission control of combustion vehicles; particularly during cold start and low temperature conditions of diesel vehicles. In this work we used a one-pot sol–gel route to synthesize a range of manganese oxide based supports doped with Ce and CeZrO 2 , as alternative low temperature diesel oxidation catalysts. We have investigated the combination of manganese, ceria and zirconia in mixed oxide catalyst supports. The synthesized samples were loaded with 1 wt% Pt and their activity in the oxidation reactions of CO and C 3 H 6 , were compared with a commercial diesel oxidation catalyst with the same metal loading. The reductions in CO and C 3 H 6 oxidation temperature T 50 of 109 K and 81 K respectively was achieved compared to a commercial diesel oxidation catalyst.