Understanding non-equilibrium N2O/NOx chemistry in plasma-assisted low-temperature NH3 oxidation

Hongtao Zhong, Xingqian Mao, Ning Liu, Ziyu Wang, Timothy Ombrello, Yiguang Ju

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Ammonia represents one of most promising zero-carbon energy solutions to address the increasingly urgent climate change problem. However, the existing utilization of ammonia faces significant challenges from low chemical reactivity and high NOx/N2O emissions, which cause severe inefficiency issues such as cold start and cycle variability of power generation, and detrimental effects on air quality, respectively. A sustainable and energy-efficient approach to tackle the above challenges is low temperature plasma which enables non-equilibrium energy and chemical utilization of ammonia such as oxidation using renewable electricity. As such, this work, for the first time, explores plasma assisted ammonia oxidation at room temperature with a focus on unveiling non-equilibrium NOx/N2O reaction pathways by combining in-situ laser diagnostics with plasma modeling. We found that the non-equilibrium plasma controls the NOx formation by supplying O/H/N atoms via electron-impact dissociation and collisional quenching of excited species. The N2O formation follows a two-step mechanism, where electron-impact reactions first provide amine radicals which further react with NOx to generate N2O. These pathways facilitate a high-efficiency and environment-friendly operation of plasma assisted ammonia oxidation with enhanced reactivity and reduced NOx/N2O emissions through manipulating mixture compositions and plasma discharge parameters.

Original languageEnglish (US)
Article number112948
JournalCombustion and Flame
StatePublished - Oct 2023

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • General Physics and Astronomy


  • Ammonia
  • Laser diagnostics
  • NO/NO chemistry
  • Nitrogen cycle
  • Plasmas
  • Sustainable energy


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