oa Catalytic Decomposition of Methane for Energy Efficient Use of Natural Gas

The catalytic decomposition of methane (CDM) on suitable surfaces offers the prospect for lower or zero-carbon routes to energy using natural gas or methane derived via biomass options. The carbon from the decomposition could be stored (buried), used for specific applications or perhaps converted to electricity using carbon fuel cells, according to which the overall process is near-zero or low carbon dioxide producing in character. A large volume of work now describes the action of supported nickel in the CDM reaction. However, the basic ground rules governing activity, longevity (closely related to carbon yield) and carbon morphology as well as issues around practical reactor systems for the sustained catalytic action of solid catalysts remain to be developed. In nickel/titania systems the carbon type and yield are dependent on nickel loading levels, with lower Ni loadings favouring higher carbon yields per unit of Ni. The carbon yield per unit mass of catalyst in nickel-titania systems is largely independent of Ni loading. Carbon yields are greatly influenced by the nature of the catalytic solid. Addition of Cu or La can lead to unusually high carbon yields in excess of 2000 g/gNi, some of the highest ever reported. The nature of zeolite morphology in Cu-Ni systems also greatly influences the carbon yield and examples of this behaviour will be presented and discussed. Considerations of how to regenerate CDM catalysts, or slowing their deactivation in the first place are demanded if sustained practical CDM is to be achieved and some ideas on the issue may be developed from experiences with other methane decomposition systems, including non-catalytic approaches that have been pursued using concentrated solar energy, for example.