[marcosdumay]

About the first point, you are expecting total combustion of a solid. That is hard to achieve. By your theory coal should also burn cleanly, and it evidently doesn't.

With enough temperature and a high oxygen pressure, graphene will burn cleanly. But also will your furnace, and my bet is that both will do so at roughly the same temperature and pressure.

About the second point, oxygen does not react well with graphite because it's entire surface does not let its electrons go very easily. Graphene has similar properties. Water does catalyze the burning of graphite, it may very well do that to graphene too.

[nine_k]

Coal has lots of other stuff mixed in to carbon: notably sulfur, and up to 10% of non-burning minerals (ash), often containing significant amounts of radioactive uranium and thorium.

Pure carbon (as in graphene) should burn much more cleanly, provided abundant oxygen.