[Don W]

Sorry, but you are quite mistaken. Ref:

fact, not friction.

You forgot that ANY gas can be liquefied. All you need is enough pressure OR a low enough temperature.

Or a suitable combination of both.

[thackney]

Sorry, you need to understand Critical Temperature.

http://www.chem.purdue.edu/gchelp/Liquids/critical.html

Gases can be converted to liquids by compressing the gas at a suitable temperature.

Gases become more difficult to liquefy as the temperature increases because the kinetic energies of the particles that make up the gas also increase.

The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied.

[thackney]

You may want to also notice the chart you linked stops at

190.53°Kelvin, which equals -116.7° Fahrenheit

Above that temperature, which is the critical temperature for methane, no liquid state exists, regardless of pressure.