Question

how does methane change to methanoic acid?

Answer 1

Methane can be oxidised to methanoic acid using hydrogen peroxide as oxidising agent and a zeolite as a solid catalyst.
${\mathrm{CH}}_4+{\mathrm{H}}_2{\mathrm{O}}_2\underset{\mathrm{zeolite}(\mathrm{H}-\mathrm{ZSM}-5)}{\overset{373\mathrm{K},2.6\mathrm{MPa}}{\to }}\mathrm{HCOOH}+{\mathrm{CO}}_2+{\mathrm{H}}_2\mathrm{O}$