Conversion of propane to methane
This probably defies the purpose, but still. Two-step process with steam reforming and Fischer–Tropsch synthesis

$\ce{C3H8 +O2 +H2O -&gt; CO + H2 + CO2}$

This step is usually performed with methane over nickel catalyst, but should work with propane as well. Remaining water is condensed and carbon dioxide is separated using triethanolamine as absorbent. Then a reverse reaction is performed

$\ce{CO + 3 H2 -&gt; CH4 + H2O}$

depending on catalyst, and exact conditions it is possible to get methanol, linear alkane/alkene mix or methane. AFAIK, $\ce{Ni}$ catalysts favor methane formation, while cobalt and iron favor linear alkanes and terminal linear alkenes.