# Storage of methane in mineral oil or other liquid hydrocarbons

Is it practical (or even possible) to store gaseous alkanes such as methane or ethane in liquid non-polar solvents, such as mineral oil or vegetable oil, and how much more (or less) methane can be stored for a given pressure with solvent vs. no solvent?

After some research, I found that butane is sometimes dissolved in gasoline to make it evaporate more easily in cold weather. So it's definitely possible. However, I cannot find solubility figures (hence this not being an answer).

• You seem to be putting methane and butane in the same basket, which is not entirely appropriate. Butane itself can be liquefied by applying a little more pressure; it is safe and convenient enough to be used in cigarette lighters. Methane is quite a different story. Sep 13 '16 at 5:26
• @IvanNeretin Yes, I know that -- I've liquefied butane by applying pressure to it in a syringe, it is very easy. However, since they are both nonpolar molecules, I figured that the answer would be the same. I will change butane to ethane, though, as ethane can't be easily liquefied. Sep 13 '16 at 8:38
• – user7951
Sep 13 '16 at 11:04
• Or even in water: en.wikipedia.org/wiki/Methane_clathrate. BTW, acetylene gas cannot be compressed much without exploding, so the gas sold for use in welding is dissolved in acetone: "A 40 litre acetylene cylinder will hold approximately 12-13kg of acetone in which we can dissolve 5500 litres of acetylene," wssproducts.wilhelmsen.com/mediabank/store/182/… Sep 13 '16 at 23:22

"Practical" can mean different things to different people, so I am not going to comment on that.

Instead I am going to address the question, of solubility of methane in hydrocarbons, without any thought about "practicality" :)

This graph is taken from the book: Fuel and Lubricants Handbook (a simple google search lead me to it, and the relevant section appears in the preview :))

The data is reported at $50\ \mathrm{^\circ C}$ and $5000 \ \mathrm{psig}$ (pounds per square inch gauge, ungodly non-SI units. ca. $3.4 \times 10^7\ \mathrm{Pa}$ according to an online conversion)

Also, the following table from this publication:

I did not read it in detail, but the data was collected in the vicinity of 1 atm and between $25$ and $200\ \mathrm{^\circ C}$

FYI: Of possible interest could be this paper.

• I'll dig some more, and if I find something I'll edit my answer to include it Sep 22 '16 at 7:07

From what I see online, the most comprehensive data can be found in: Solubility data series (methane), Volume 27-28, Pergamon Press, Oxford, 1987 authors Clever,H.L., Young, C.L., and Kertes, A.S., IUPAC. At roughly room temperature, again from what I see online, you can store about 10 mole % in n-hexane at about 400 psi. (see Hua, et al, Chinese J Chem Eng.,13(1)144-148(2005)). I have zero idea what "practical" means...it's meaningless without some context.

A partial answer, after a few experiments: Butane is soluble in vegetable oil. The specific type of vegetable oil used is olive oil. This is the process I followed:

1. Get some liquid butane out of a butane cylinder and place it into a test tube.
2. Pour the liquid butane into vegetable oil and agitate it.
3. Repeat until vegetable oil appears to be saturated.

The vegetable oil could then be ignited directly, and burned for about 5 minutes using about 100mL of vegetable oil. Usually, oil does not burn unless heated significantly. This indicates that the butane was, in fact, dissolved into the oil.

I have yet to try the same experiment with propane, ethane or methane.