Has anybody tried zeolite as a drying agent - water removal after washing? I hear they use this in processing ethanol. Any experience with this??
It certainly sounds like a good idea, and I've wondered the same thing myself. I imagine the reason it is not more common is becuase the cost of the zeolite beads themselves or the cost of energy needed to regenerate them makes it not cost-effective. Or maybe nobody has thought of it yet is all. I've not looked at the costs yet, so I couldn't say.
I just priced it this morning. 25lb pail $118, 100lb bag $365.
I'm not sure how their price compares with anyone elses...
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Yeah, that certainly sounds not-cheap. Also, how much use one can get out of a volume of the zeolite beads will affect how cost-effective their use is. If the beads are spent after only a sigle pass, then their use probably isn't cost effective on a small scale use. Which would be a shame. Zeolite seems like such an elegant and simple solution for water removal to me.
I have a fair amount of zeolite that I have used for drying (m)ethanol. It works great, but a significant amount of heat is generated in the adsorption process. I made a long winded, rambling post about my zeolite/ethanol experiments here:
In short, if you read the blurb on jtf about using zeolite to dry alcohol, then drying the zeolite in your oven: DONT!
Also, you won't be able to dry room-temperature zeolite with a vacuum in a reasonable amount of time (days), and drying zeolite in an oven releases nasty fumes. Your wife will hate you, and you'll solve all your insect/pet/unwanted guest problems at once.
Commercial operations use zeolite with alcohol all in a vapor phase, then massive vacuum pumping to dry the zeolite while it is still hot, as in 200C hot. Keep in mind your vacuum will have to handle lots of water vapor, which limits your choices of pumps to a liquid ring or venturi pump.
DON'T use zeolite or similar compounds to dry Methanol!!!
Zeolite molecules are formed to trap molecules of a particular size; that's why there are different ratings for Zeolite. Unfortunately, methanol and water as similar enough in size that the zeolite compounds aren't selective enough to choose one over the other. Zeolite in a water/methanol mixture will absorb both.
Ethanol is larger than methanol and water, so Zeolite designed to trap water will not capture Ethanol.
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I have used zeolite to pretreat oil: it removes solid stuff and post-treat biodiesel and seems to particularly good at clearing up the haziness produced by using used cooking oil. It also removed water.
Hey everybody, as you all know, biodiesel can be brewed using ethanol. One of the reasons that almost nobody uses it is that ethanol is more expensive than methanol. One of the other reasons is that even if you get a BATF liscence to brew/distill it, alcohol is hydrophilic (water loving). As we all know, any more than a few percent of water will slow the reaction and cause saponification (soap) instead of transesterification (bio-d). Back when I still wanted to commercially brew bio-d, I looked very seriously at ethanol. Aside from being a non-petrolium product (methanol is), it is possible to brew/distill ethanol cheaper than buying bulk methanol. The biggest obstacle to brewing bio-d with ethanol is that last stubborn 3-5% water that can't be easilly removed. For those who have bothered to read this far, here's the payoff. Through internet research, I discovered that cornmeal can be used to dry the last few percent of water out of ethanol. Using advanced search, Google: cornmeal adsorbtion (in phrase category) with water and alcohol (in all the words category). If the sites still exist, you should find some interesting stuff. Remember the guy using flour to settle his product? The flour sucked up the last little bits of water that had stolen some lye from the methanol and was trying to make soap. Ethanol can gradually grab enough water out of the air to complicate the bio-d reaction. I'm just guessing that a couple feet of cornmeal sandwiched between a 100 micron filter and a 10 micron filter would dewater hot bio-d quite nicely. Imagine it as an in line dehydration assemly inside a piece of pipe with quick disconnect fittings (camlock, not hosebarb)so you can remove one of the filters and dump your soggy cornmeal into your ethanol fermenter. 100 microns upstream, 5 or 10 microns downstream. What do you think?
Am new to the forum so please be gentle. I am a process design engineer who haas recently moved into the world of bio-diesel. Having spent years in pharmaceuticals and one particular area being multipurpose solvent recovery distillation columns I can say that big pharma has looked at this problem and certainly the industry standard with ethanol drying is to use distillation. Bearing in mind the volumes of solvents used in pharma can be massive and and most multipurpose columns can feed up to 6000 kg/h of various solvents. In pharma, moisture content of ethanol is very stringent at 99.95 to 99.99 % ethanol required. There are a few ways to run the columns but the most common is to use an entrainer to break the water / ethanol azeotrope (one of the trickiest to break). This usually requires a two or even three pass pressure swing distillation. One of the neatest solutions I have run though is a two pass extractive distillation using ethylene glycol. The problem with zeolites as correctly pointed out is the cost of the zeolite itself and then the regeneration costs can make it prohibitive...the energy used for a distillation solution can be more efficient even with the requirment for more than one pass.
Although there have been threads about distillation, the focus was mostly to dry bio-d not ethanol. Using a makeshift still to boil water out of bio-d is much safer than boiling ethanol out of water. Adsorption is probably easier and safer. When I mentioned throwing the soggy cornmeal into a fermenter that implied ethanol production. That was more for some soy or canola farmer with his/her own crusher/expeller who wanted to start a small commercial bio-d plant. Somebody playing around in the garage probably wouldn't want a potential bomb (ethanol still) around the house. A heat tolerant pump, a well grounded in line heater, and a cornmeal adsorption system would probably dry bio-d safely and cheaply. Better than zeolite. Compost the soggy cornmeal or throw it in the trash.
further surfing/research shows zeolite 3A not absorbing methanol while cornmeal/grits will.
China Sea Pirate, Barney27 started the thread off on the subject of using zeolite for water removal after washing. This would normally imply that the methanol/glycerol layer had already been drained off. Cornmeal in a tank that contains only biodiesel and traces of water can't absorb methanol from accross the room where the methanol is in another container with the glycerol.
sorry to get so far off topic, your right of course. but in general its eaisier to use an existing thread because of the greater # of people reading it to find information or answers than it is to start a new one.
what i really want to know is how much if any methanol would zeolite #3a absorb if used to remove water from an acid reacted stream of biodiesel containing about 3% volume methanol and 3000 ppm water. do you know? i think it would be zero but the factory rep won't give a definate answer without first implying that i could be making terrorist bombs or something. seems easier to dry the beads than the whole stream of oil. and i wasn't really knocking cornmeal as i clearly knew that cornmeal couldn't absorb methanol from across the room before i posted.
A couple people (or at least one person) mentioned that a 3A or 4A zeolite mole sieve will absorb both methanol and water. This is true. HOWEVER, and its a huge however, you can find a mole sieve material that will preferentially adsorb water vs. methanol. Yes, you will probably still suck up a little methanol, but, if your primary objective is methanol purity, then a mole sieve is a good way to go.
Regenerating mole sieve media in an oven is retarded. Don't do it.
They sell mole sieve vessels for about 600 or 700 bucks. These will come with a built in heating element, plus they will be plumbed with inlets, outlets, drains and vents.
I can provide bulk zeolites. Packaging is in drums and each drum will be 55 gallons each.
Here is a quote from Lancaster synthesis ltd.
Molecular sieve of 3 angstrom pore size of particular use in the drying of liquids especially methanol and ethanol.
A detailed comparison has been made of the drying of various alcohols using 3A or 4A powder or beads.
In general the powder form is more effective for ethanol, 2-butanol,t-butanol and ethylene glycol but beads are better for methanol.
In all cases studied 3A sieves were more effective than 4A
3A Zeolite Molecular Sieves (A = Angstrom = Å = 0.1nm)can be used for drying alcohols such as Methanol or Ethanol as well as Biodiesel - the critical diameter of the pores within the crystals are too small to absorb Methanol and Ethanol. Water molecules have a diameter of about 2.75Å (theoretically there is ~5% variation dependent upon the axis chosen) The molecular diameter of Methanol is about 4.1Å. Ethanol is about 4.5Å. Methanol and Ethanol can be considered borderline size for 4A molecular sieves which have been shown to absorb these molecules to some extent, but 4A molecular sieves would still be a fine for drying biodiesel. 5A molecular sieves could be used to absorb Methanol.
Biodiesel resistant Zeolite Molecular Sieves can be bought here - http://www.biofuelsystems.com/shop/index.php?cPath=68
I am interested in how much Molecular Sieve is needed for drying the Sodium Methoxide.
Assuming 18g water released when dissolving 40g hydroxide.
A 100L batch of virgin oil would need 350g which would release 160 g water.
Assuming Zeolite absorbs 20% by weight then 800g zeolite would be required to dry the methoxide.
In practice more is needed when the extra catalyst is added to account for the titration value for wvo.
The Zeolite can however be regenerated and reused.
I should also add that if this works i would expect an exothermic reaction with a large volume of hydrogen given off with possibly a violent reaction.
The resultant water would only contribute about 200 ppm to the final bio anyway so i am not sure if it is worth doing.
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