Natural gas vehicle fuel station (© 2008 Mario R. Duran):
Catalyst development for low-temperature methane combustion has received significant attention due to the growing market of alternative fuel vehicles, such as natural-gas vehicles (NGV) or biogas-powered vehicles. Natural gas has the highest energy/carbon ratio of any fossil fuel and produces the lowest emissions of not only CO2 but also other pollutants (NOx, SOx, particulates, CO).
With demand rising, the market is not yet ready to meet the environmental and economic implications of the new technology. Methane itself has a global warming potential (GWP) that is 28-36 times higher than that of CO2 over 100 years (data from the U.S. Environmental Protection Agency). As a result, in 2016 in Canada, methane emission control was put in place. Practically, the only way to eliminate these emissions is through the use of a catalytic converter, which constitutes the heart of an exhaust gas treatment system.
CH4 is the most difficult of all hydrocarbons to burn, meaning that larger amounts of expensive noble metals must be used in the converters. Palladium catalysts are also subject to deactivation by water present in the engine exhaust and by sintering at high exhaust temperatures.
These indicate the immediate need for an efficient CH4 combustion catalyst with the lowest possible noble metal loading and the smallest size and cost of the converter, which should at least be stable for the NGV lifetime. In our laboratories, we use a mindful combination of colloidal chemistry techniques to develop the required catalysts, which are tested under practically-relevant conditions.
A representative publication:
100° Temperature reduction of wet methane combustion: highly active Pd–Ni/Al2O3 catalyst versus Pd/NiAl2O4 (ACS Catalysis, 2015):