Hi all , a quick question, when mixing the methanol and koh in a sealed drum can I let it dissolve and store for a couple of hours to make sure it is dissolved with gentle agitation, or will it "go off".
Your replys are much appreciated thanks.
P.S I will be mixing 18.5 L of methanol to the Koh in a plastic drum which is hard to see into. They are quite thick oil containers.

It wont go off in a few hours. I've kept methoxide made up for a week at a time. Ensure the container is sealed and almost full to reduce water passing into the methoxide.

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Joe Morgan
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Thanks Joe

The methanol will become heated during the reaction of dissolving KOH in methanol. To prevent excessive pressure build up, I recommend releasing the pressure a couple of times , after the container has sat for abvout a minute after agitation, so that there is negligible methanol able to be forced out by the pressure.

If the methanol cools down after the KOH has all dissolved, it is prudent to allow some air in, to prevent crushing of the container as this could cause leaks.

After the continer and contents are at ambient temperature, the drum should be closed tightly to prevent any airflow in/out of the drum until it is needed.

There should not be any noticable degradation of the solution over time if the drum remains sealed.

Regards,
Tony

Thanks for the info Tony.

Gday Tony,When KOH is mixed with methanol in a sealed container how much air pressure is generated? Also would the pressure be the same if you are mixing 20litres or 200litres?I am at present fabricating a methoxide mixer that i will be able to mix 200 litres of methanol.The cylinder is the top part of two hot water heaters joined together so it looks like a truck fuel tank that is 1.3 metres long and .5 metres wide.Inside the tank i have welded baffles to help dissolve the KOH.The opproximate capacity of this tank is 250 litres and it has a 1" shaft going through it where the anode was.I have filled this tank today with 200 litres of water and pressurized it to 25 psi and it has 4 leaks that are weeping.I have yet to make the frame so the tank can rotate at about the same speed as a cement mixer.My plan is that i decant 200 litres into tank from back of vehice (save manhandling 200 litres) add required amount of KOH and seal tank up.Rotate 10 minutes,stop,connect hose and apply to oil in reactor.To empty methoxide out of tank i will intermitley apply air.Until i do this i dont know what air pressures i am dealing with when KOH is mixing with methanol. I have plenty (4) of places to install a pressure relief valve.regards westwinds

I do not have the answer to your question, however the pressure increase needed to bulge the 20 litre HDPE drumms is low. My concern is if the HDPE has been degraded by sunlight and cracks. Pressure would allow the mixture to be expelled more than just when shaking. It is mainly due to heating of the airspace and added methanol vapour due the the higher temperature of the methanol.
Providing the methanol does not actually boil, I believe that your steel tanks, once the leaks have been fixed, will easily take the pressure.

Regards,
Tony

Gday Tony,Thank you for responding to my questions.I will post some pictures when the mixer is built and i will be making a batch in 5 weeks time and i plan to check the air pressure at different stages of mixing.My reactor is used most of the time as settleing tank. regards westwinds