Nitrogen Oxide Reduction

A catalytic treatment of nitrogen oxides from lean burning engine exhaust.

The Need

The choice of reducing agent for the reduction of nitrogen oxides in lean combustion exhaust streams is critical to limit pollution. Hydrocarbons are ideal reducing agents because they are present in the exhaust stream of many applications, but reduction of nitrogen oxides is difficult to catalyze due to the presence of hydrocarbons lean-burn conditions. Development of a method to reduce nitrogen oxides with a hydrocarbon as a reducing agent is necessary to mitigate the release of pollutants during lean combustion.

The Technology

Researchers at The Ohio State University, led by Dr. Umit Ozkan, developed a system for the reduction of nitrogen oxides from high oxygen concentration combustion exhaust using methane as a reducing agent. The system is comprised of a two catalysts, one for oxidation of nitrogen oxide to nitrogen dioxide and a second for the reduction of nitrogen dioxide with methane to nitrogen, carbon dioxide, and water.

Commercial Applications

  • Pollution reduction


  • Reduces nitrogen dioxide at a rate three times greater than current industry processes
  • Two-stage reaction improves the reduction of nitrogen oxide under lean combustion circumstances
  • Palladium-based sulfated zirconia catalysts reach 64% nitrogen yield from nitrogen dioxide
  • Cobalt based catalysts are capable of reaching a 90% nitrogen dioxide yield nitrogen oxide
  • This process may revolutionize nitrogen scrubbing in the private energy sector
  • Higher yield, as compared to industry standard
  • Highly efficient process

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