Diesel Catalysts: Catalyst Systems
Nett® Diesel Exhaust Catalytic Purifiers are available with two different catalyst systems:
- M-Series catalyst
- D-Series catalyst
The M-Series diesel oxidation catalyst yields a balance of high hydrocarbon, carbon monoxide, and particulate matter (SOF) conversion with low sulfate formation.
Nett Technologies offers several D-series catalyst coatings which are engineered for different applications. D-series catalysts incorporating sulfate suppressants for good high temperature DPM conversion, what makes them suitable for heavy duty applications, are also available. Request the Nett D-series Diesel Oxidation Catalysts Data Sheet for more information.
The exact emission performance of either catalyst type depends on the catalyst size, exhaust temperature, and raw exhaust composition. A minimum temperature of about 180°C (360°F) is required for conversion. Best catalyst performance occurs at temperatures above 250-300°C (480-570°F) when the conversion of carbon monoxide exceeds 90%. Typical CO and HC performance curves of the Nett® M-series diesel purifier are shown on our Emissions FAQ page. Conversion of diesel particulate matter in the catalyst depends on the composition of the particulates and the sulfur content of the fuel. Achievable particulate matter reductions amount to 30-50%. Low sulfur diesel fuel is strongly recommended for best catalyst performance.
The D-Series catalysts show a significantly improved hydrocarbon performance at low exhaust temperatures. An example performance chart is shown in the Emissions FAQ page. It is important to understand that the low temperature HC activity is due to the adsorption on the HC trapping material rather than due to catalytic oxidation. Since the adsorption capacity is always limited and the HC traps have to be periodically regenerated by higher exhaust temperatures, this type of catalyst system is effective only at transient engine operation. The amount of HC trapping material in the Nett® D-Series catalysts is sufficient for a maximum of 15 - 30 minutes of continuous low temperature HC and odor control.