In some regions of the world, emissions of total organic carbon (TOC), including methane and non-methane hydrocarbons (NMHCs), from the tail pipe of natural gas or biogas fuelled combustion equipments are strictly regulated (e.g. 150 mg/Nm3 of exhaust gas in Italy). Post combustor has been widely chosen in response to the TOC emission targets. TOC typically consists of >90% methane — a strong greenhouse gas and the most challenging compound to remove due to its highly stable form. Thus, more gas is being consumed to burn the TOC present in the exhaust, resulting in higher operating (or power production) costs.
A passive catalytic approach is an alternative to post combustor. Palladium based oxidation catalyst is known to actively remove TOC, providing no sulfur compounds present. Sulfur poisons and deactivates the catalyst in a short time. This paper presents a concept to extend the life of the oxidation catalyst by using an exhaust post conditioning system. The system is designed to eliminate and withstand contaminants, yielding a protection to the catalyst. Consequently, the catalyst life is prolonged by about 50 times.
