Plasma Catalytic Treatment of Automotive Exhaust Gases and Effective Parameters

The increasing consumption of fossil energy resources, for both stationary electrical power and transportation, has led to greater environmental pollution. The international regulations for exhaust gases from cars and from industry restrict the contamination to values difficult to handle with conventional removal technologies like thermal and catalytic oxidation or adsorption. Nitrogen oxides (NOx) are mixtures of compounds of nitrogen and oxygen generally found in effluents from combustion sources. In the field of catalysis, one application that has been classified as a breakthrough technology is the catalytic reduction of NOx in oxygen-rich environments using hydrocarbons. However, until now, no satisfactory catalyst has been found and the coupling with a non-thermal plasma discharge (NTP) can bring some new possibilities for NOx reduction as far as it is associated to a catalyst sufficiently active and stable. An understanding of the plasma chemistry serves as an important design tool for minimizing the electrical energy consumption of the process and identifying the process products. In this paper, this technology has been investigated and the effective factors on this process have been reviewed.