In situ regeneration of Rhodium in three-way catalysts by aqueous ethanol injection for sustained methane emissions abatement

Abstract

We are reporting an initial feasibility study addressing the abatement of methane emissions from stoichiometric natural gas fueled vehicles. The injection of a small amount of aqueous ethanol or propane into the exhaust enables the catalytic abatement of methane by the Rh-containing three-way catalyst (TWC). The Rh component experiences oxidation to inactive Rh3+ when the engine operates during the fuel shtitoff mode raising the catalyst temperature to over 1000 degrees C. Upon returning to normal driving operation, under a slightly fuel rich condition, the methane will not reform leading to permanent deactivation of the Rh. Injecting an aqueous ethanol solution or gaseous propane catalytic steam reforming occurs and the Fly generated reduces the Rh3+ to its metallic and active state for CH4 steam reforming. This paper presents a laboratory feasibility study for in situ catalyst regeneration of Rh3+ to Rh metal using a secondary injected fuel (ethanol or propane), enabling sustained catalyst performance in methane emissions abatement (C) 2017 Elsevier B.V. All rights reserved.