At the present stage developed Ru a

At the present stage developed Ru and/or Ni catalysts are approaching practical use. In order to put them into practical use, sophisticated catalysts with high stability (more than40 000 h)89 and high activity should be developed. Long-term tests for selective CO methanation over the developed catalysts have recently been conducted, as summarized in Table 1.A large number of developed catalysts show great activity for CO methanation, while they need stability improvement because they work for less than 10 000 h. Thus it is expectedthat clarification of the deactivation mechanism of selective CO methanation catalysts is next on our challenge, which will allow the development of new suitable catalysts with high activity and selectivity for CO methanation.