CUED Publications database

Characterization and Evaluation of Methane Oxidation Catalysts for Dual-Fuel Diesel and Natural Gas Engines

Worth, DJ and Stettler, MEJ and Dickinson, P and Hegarty, K and Boies, AM (2016) Characterization and Evaluation of Methane Oxidation Catalysts for Dual-Fuel Diesel and Natural Gas Engines. Emission Control Science and Technology, 2. pp. 204-214.

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Abstract

The UK has incentivized the use of natural gas in heavy goods vehicles (HGVs) by converting to dual-fuel (DF) diesel-natural gas systems to reduce noxious and greenhouse gas emissions. Laboratory and on-road measurements of DF vehicles have demonstrated a decrease in CO$_2$ emissions relative to diesel, but there is an increase in greenhouse gas (CO$_2$e) emissions because of unburned methane. Decreasing tailpipe emissions of methane via after-treatment devices in lean-burn compression ignition engines is a challenge because of low exhaust temperatures (~400 °C) and the presence of water vapor. In this study, six commercially available methane oxidation catalysts (MOCs) were tested for their application in DF HGV vehicles. Each MOC was characterized in terms of the catalyst platinum group metal (PGM) loading (both Pd and Pt), particle size, catalytic surface area, and Pd:Pt ratio. In addition, the washcoat surface area, pore volume, and pore size were evaluated. The MOC conversion efficiency was evaluated in controlled methane-oxidation experiments with varying temperatures, flow rates, and gas compositions. Characteristic-conversion efficiency correlations demonstrate that the influential MOC characteristics were PGM loading (both Pd and Pt), Pd:Pt ratio, washcoat surface area, and washcoat pore volume. With 90 % methane oxidation at less than 400 °C in DF HGV exhaust conditions, sample 1 had the highest conversion efficiency because of a high PGM loading (330 g/ft$^3$, 12,000 g/m$^3$), a 5.9 Pd:Pt ratio, a high alumina washcoat surface area of 20 m$^2$/cm$^3$, and 74-mm$^3$/cm$^3$ pore volume. Additional studies showed increased MOC conversion efficiency with decreasing gas hourly space velocities (GHSVs) and increasing methane concentrations.

Item Type: Article
Uncontrolled Keywords: methane oxidation catalyst dual fuel heavy goods vehicles (HGVs)
Subjects: UNSPECIFIED
Divisions: Div A > Energy
Div A > Fluid Mechanics
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 19:55
Last Modified: 24 Aug 2017 01:28
DOI: