Low Temperature Plasma Assisted Catalytic Reduction of NOx in Simulated Marine Diesel Exhaust

Plasma Assisted Catalytic Reduction (PACR) of NOx has been investigated at laboratory scale for gas stream compositions representative of marine diesel exhausts. PACR NOx reduction in excess of 90% was measured at 350°C, a plasma specific energy of 60 J/l and two NOx concentrations (1,200 and 1,800 ppm). PACR NOx reduction of over 50% was measured for simulated marine engine conditions at 250°C, 60 J/l and 1,200 ppm NOx. The performance under these conditions could be increased, achieving a peak of ∼74% NOx reduction, although at a relatively high plasma power. Water, present in diesel exhaust, was shown to inhibit the poisoning effects of fuel sulphur using SO2 as a representative exhaust component. The PACR system performance demonstrated tolerance to simulated fuel sulphur levels of up to 1% for the duration of the tests. PACR performance was also shown to be sensitive to the amount of hydrocarbon reductant used.