methanol too wet

[B100]

Working with an IBC of methanol from my usual supplier, every batch is proving problematic.    My process uses KoH.  So tested the methanol SG and found the probable cause.   The SG of virgin methanol should be 0.791, but this IBC is 0.780.    I'm using a laboratory-grade hydrometer which has always been spot on with previous IBCs, so it looks like I've got a wet batch of methanol. 

There is a lot of info on the web about the consequences and problems caused by using wet methanol, but I can't find any advice on how to cope with it.   Any suggestions - apart from going back to the supplier (which I will try tomorrow) ?

[dgs]

I'M not quite with you here. Surely if you had water in your methanol your sg would be higher not lower. I've use methanol containing 1% water and it doesn't give a significant yield reduction.

What are the problems you are finding. You can dry your potassium methoxide using quick lime (calcium oxide) its a bit of a mess about but it works really well if you do it correctly.

[B100]

If the SG should be higher with extra water content, what conclusion should I draw if the SG is lower than expected ?

The problem I have is that using "standard" quantities of methanol and KoH (which I have been using for 9 years), the conversion to bio and glycerine fails to take place.   I have to then run a second process using about 30% more methanol and KoH.  I have tried running the second process with 10% and 20% extra, but without success.   Nothing else in the overall process has changed.   The KoH is kept dry and the used vegetable oil is always dried using glycerine from the last process. 

[countrypaul]

As Dave says, if your methanol has water in it the SG will increase. Can we assume that the SGs were measured at the same temperature and that temperature was what the hydrometer was calibrated at? If the SG of your methanol is lower it could be contaminated but I cant gues what with.

When you use 30% extra methanol and KOH do you end up with lots of extra soap (gylc)? Water catalyses the formation of soap so if the methanol had lots of water present we would expect more soap. I have used 97% methanol (3% water) and whilst I used NaOH the amont of soap was slightly higher but not worryingly so.

Can you check the acid value of your methanol? I don't know if you normally titrate your oil, but if so try titrating some methanol and let us know.

Can you try a Dr Pepper with 30% more KOH but the same amount of methanol?  Just wondering if the methanol could have methanoic acid (formic acid) present - though I have no idea what that would do to the SG - I would guess increase it.

Have you got any other KOH or NaOH - if so try a Dr Pepper with that and see if it works normally. You can buy 500g oh NaOH from a pound shop fairly easily if you want but check to make sure it is just NaOH.

[B100]

Wow.  I have just called my supplier and have discovered that I am not the first person to complain about their methanol.   They took responsibility straight away.  They are going to collect what's left in a couple of days and replace it ASAP.    I am impressed by their response, but I am out of pocket by quite a lot for wasted oil as the conversion rate has been reduced by 30%, and I have obviously used unnecessary electricity and KoH.   

Thanks for all your help in trying to troubleshoot this one.   Much appreciated. 

[dgs]

Are we allowed to ask who the supplier is.

[DavidA]

I notice that Isopropanol is .785 at 20 C

Any chance that you have a mixture of Methanol and Isopropanol ?

Could be why the supplier is so quick to change it.

[B100]

I was unable to find out what the contaminant might be, but they were certainly very quick to agree to replace the IBC.   The supplier was Bonnyman.     It will be interesting to see how they react when I ask for compensation.   The hassle this has caused has taken a lot of extra time as well as wasting feedstock (which is hard to come by in this area), KoH and electricity. 

[dgs]

If It was IPA doesn't that work out at around 50% surely at that you would be able to smell that sweet aroma.

[B100]

As it happens, I just happen to have 5L of IPA that has only just been opened.   I will try the sniff test tomorrow in daylight to see if I can detect any in the methanol.   I can't say that I'm particularly optimistic as my sense of smell has become impaired over the years by too many curries. 

[nigelb]

Ask for a C of C....a certificate of conformity for the batch you receive. Virgin methanol should be just that...virgin. I'll find out tomorrow from my boss to see if reclaimed also carries a potential c of c.

[B100]

My plan is simply to measure the SG from now on of any incoming IBC.   

[nigelb]

For your own satisfaction do just that. My advice would be to ask for the certificate and complain the moment you think there is a problem with it. Suppliers have a duty of care and will respond quickly. Without being certain, and it is wise to ask questions of Bonnymans, but I beleive they are not manufacturers of methanol. Very much like ourselves. We buy ours in from Brentag or Tennants. We always ask for the conformity certificate.

Bonnymans may of knowingly or not knowingly supplied you with reclaimed methanol instead of virgin. You requesting a copy of the c of c will tell them you mean buisness.
 

[DavidA]

If It was IPA doesn't that work out at around 50% surely at that you would be able to smell that sweet aroma.

It might be an idea to keep back a couple of Litres of the bad stuff as evidence.

Maybe use some of it for distillation tests if you feel so inclined.

[WesleyB]

A fractional distillation aparatus could give you the boiling point of your  material or materials .   It would be some trouble .   If you took about 50 milliliters of the alcohol in a beaker then put a couple of grams of  sodium bicarbonate into it , then if bubbles are produced you've got water in it , not just alcohol .