O2+ 4H+ +4e- = 2H2O
总的式子:2CH3OH+3O2=2CO2+4H2O
3O2+ 12H+ +12e-=6H2O
相减：2CH3OH - 12H+ -12e
=2CO2-2H2O带负号的移到对面去：
2CH3OH+2H2O-12e-=2CO2+ 12H+