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With forthcoming 2014 EPA GHG legislation capping methane emissions at 0.10 g/bhp-hr for heavy-duty engines, development of a thermally stable and sulfur-tolerant methane oxidation catalyst becomes more critical. This is particularly true for natural gas-powered engines where methane slip is a significant contributor in the emissions and sulfur is present as a constituent of odorants used in CNG. Scientists at Clariant have recently developed a novel process for manufacturing a PGM containing zeolite that is both thermally stable and resistant to sulfur poisoning. Methane oxidation catalysts typically require temperatures in excess of 400°C to achieve light-off and are often sensitive to exposure to sulfur. The PGM zeolite catalyst has shown remarkable activity at low temperatures and a resistance to sulfur poisoning. Tests have shown that even after exposure to heavy concentrations of sulfur, the catalyst has little change in activity.

Technologies for exhaust aftertreatment of diesel engines are driven by emission standards and Selective Catalytic Reduction (SCR) will play a key role in complying with the requirements, particularly for the heavy duty vehicles. Amongst the variety of catalysts for the SCR reaction, the Vanadium-Tungsten-Titanium-Based (VWT) system is preferred over the base metal doped zeolite because of the established advantages of wide temperature window, robust and durable performance and resistance to sulfur exposure. While the basic chemical reactions involved in ammonia-SCR are well known, the challenge lies in identifying the right combination of substrate and wash coat formulation to meet with customer specific requirements. An insight into the relevant materials properties of the substrates as well as the bulk surface properties of the wash coat such as its ammonia storage capacity, V2O5 dispersion and stability are important.