Effects of Exhaust Gas Hydrogen Addition and Oxygenated Fuel Blends on the Light-Off Performance of a Three-Way Catalyst

A significant amount of harmful emissions pass unreacted through catalytic after-treatment devices for IC engines before the light-off temperature is reached, despite the high conversion efficiency of these systems in fully warm conditions. Further tightening of fleet targets and worldwide emission regulations will make a faster catalyst light-off to meet legislated standards hence reduce the impact of road transport on air quality even more critical. This work investigates the effect of adding hydrogen (H₂) at levels up to 2500 ppm into the exhaust gases produced by combustion of various oxygenated C₂-, C₄- and renewable fuel molecules blended at 20 % wt/wt with gasoline on the light-off performance of a commercially available three-way catalyst (TWC) (0.61 L, Pd/Rh/Pt - 19/5/1, 15g). The study was conducted on a modified naturally aspirated, 1.4 L, four-cylinder, direct-injected, spark-ignition engine. The experiments were performed at the steady-state condition of 1600 r/min and BMEP of 3.6 bar, derived from a time-based load distribution of a WLTC cycle simulation, with levels of gaseous pollutants, particulate matter and hydrogen measured both upstream and downstream of the TWC. Low-level H₂ addition reduced the TWC light-off temperature of CO, THC and NOₓ, and decreased the time to reach steady particulate number/ mass levels post-TWC. The presence of C₂- (ethanol, acetaldehyde, diethyl ether) and C₄- (1-butanol, butyraldehyde, 2-butanone, methyl tert-butyl ether) molecules displayed minimal impact on the conversion efficiencies relative to operating the engine with pure reference gasoline. Linalool and γ-valerolactone blends displayed a slight increase in light-off temperature and produced elevated levels of particulates pre and post catalyst, while 2-methylfuran and 2-methyltetrahydrofuran blends emitted lower levels of particulates. Hydrogen levels post-converter were found to reach almost full conversion after H₂ light-off, independent of the amount added, however after CO light-off the conversion of the additional H₂ was reduced significantly.

Language

  • English

Media Info

  • Media Type: Web
  • Features: Figures; Illustrations; References; Tables;
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01743290
  • Record Type: Publication
  • Source Agency: SAE International
  • Report/Paper Numbers: 2019-01-2329
  • Files: TRIS, SAE
  • Created Date: May 4 2020 3:28PM