GP asked about sequestration. Most of the productive economic uses for CH4 require
burning it. Liquid synfuels are great and wonderful but they are carbon neutral!
You can use atmospheric CO2 as feedstock for plastic production, but world plastic production is only 380 million tonnes a year, while there's more than 1 trillion tonnes of excess CO2 in the atmosphere. It would take two and a half millennia to convert that to plastic.
