If the temperature is high enough, the methane decomposes to carbon and hydrogen. The reduction of NiO carries out by hydrogen.

Yes, but How it happens?

Dear Daza, 

According to our recent publications on the methane combustion over Pd catalyst, the mechanism showed that methane is dissociatively adosrbed on pd metal sites and then the adjacent PdO (oxide phase) oxidize methane to syngas (in case of lean conditions) as shown in Eq.1

PdO +CH4 ---------- CO+ H2

However, in case of oxygen rich condition, total oxidation occur as in Eq. 2

3PdO +CH4 ---------- CO2+ H2O

Please find the attached paper that might be helpful

Have a good day