Abstract
AbstractThis study investigates possible pathways to reduce water inhibition over Pd−Pt methane oxidation catalysts supported on alumina and a ceria‐zirconia mixed oxide under conditions typical for lean burn gas engines. Spatially resolved concentration and temperature profiles reveal that addition of hydrogen to the lean reaction mixture leads to significant heat production and an increase in methane conversion. Moreover, reductive pulses during operation are not only able to regenerate the catalyst deactivated by water by removal of OH‐groups from the catalyst surface, but even promote its activity after repeated application of pulsing for several hours. X‐ray absorption spectroscopy reveals the formation of a partially reduced PdO−Pd mixture during the pulsing, which explains the increase in activity. This state of high activity is stable for several hours under the tested lean conditions. The results presented in this study suggest an efficient in situ activation strategy to overcome water inhibition of methane total oxidation over Pd−Pt catalysts by careful process control.
Highlights
Groups from the catalyst surface, but even promote its activity after repeated application of pulsing for several hours
In the context of methane abatement in the exhaust of a natural gas engine by a ThreeWay Catalyst (TWC), Bounechada et al found that periodic rich pulses could recover catalytic activity lost due to water inhibition and that periodic oscillations resulted in higher and more stable catalytic methane conversion over a Pd/Rh-based TWC.[41]
An efficient after-treatment system must be able to abate this remaining methane. This is a challenge for both, lean combustion and stoichiometric combustion; in the case of the latter the ThreeWay Catalyst (TWC) is largely ineffective.[2]
Summary
As CH4 is a much more potent greenhouse gas than CO2, this CH4 slip – as much as several hundred ppm depending on the vehicle operation – may become a significant obstacle to the widespread use of natural gas as a transportation fuel.[1] an efficient after-treatment system must be able to abate this remaining methane This is a challenge for both, lean combustion and stoichiometric combustion; in the case of the latter the ThreeWay Catalyst (TWC) is largely ineffective.[2].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
