Conversion of methane to propane
Yes, it can be done by mimicking the conditions in the earth's mantle.

It was shown by Alexander Goncharov and coworkers [1] by placing methane in a diamond anvil cell, applying a pressure of more than 2 GPa and heating everything to a temperature around 1000-1500 K with a laser.

Is it economical? Hardly, but very interesting anyway!


Kolesnikov, A.; Kutcherov, V. G.; Goncharov, A. F. Nature Geosci 2009, 2 (8), 566–570. DOI 10.1038/ngeo591.