Johnson Matthey has been pioneering emission control catalysts for over 40 years. Our scientists apply their catalysis expertise to meet ever tightening emissions legislation. Recently, we turned our focus to the design and application of a new generation of selective catalytic reduction (SCR) catalyst for use on diesel vehicles. This new catalyst is even more effective at removing nitrogen oxides (NOx) emissions whether in slow speed city conditions or for high speed motorway driving.
SCR catalysts are manufactured using zeolites. These materials have a cage structure with a metal catalytic site and it is within these cages that the NOx emissions are reacted with ammonia to form harmless nitrogen. Our researchers discovered it was the small pore nature of zeolites that gave the unique activity, thermal stability and poison tolerance compared with larger pore SCR zeolite catalysts.
Through extensive screening and modelling, we discovered a new, small pore metal zeolite catalyst with remarkable activity even when exposed to very high temperatures. Applying our chemistry and engineering processing expertise, we scaled up from the lab to mass production using raw materials more efficiently and reducing water needs.
This catalyst is now being used in our flow-through SCR catalyst, and owing to its excellent durability, it's also found in a diesel soot filter - the selective catalytic reduction filter (SCRF), where very high temperatures are encountered. This SCRF can be located close to the engine, removing soot and NOx in the most energy efficient way.