Friday, May 23, 2014

Milkshake wants to buy a kilo-scale hydrogenator

Milkshake would like some help in purchasing a kilo-scale hydrogenator:
I wanted to ask the readers from process groups if they worked with a low-pressure batch stirred hydrogenation reactor that they liked and could recommend – for us to buy. Specifically,  we would need a hydrogenator that can accommodate 8-10 liters of a reaction mixture that has tendency to initially foam under reduced pressure (this means that the total available volume should be about 15-20 liters). Maximum operating pressure 3 bar would be enough, no heating or cooling is required and the typical solvent is water. I am not really interested in flow hydrogenation systems because they would be unsuitable to our particular case. A glass vessel or at least a glass window on the top would be nice to have, because of the foaming problem during evacuation.  Thank you for your suggestions!
I don't have a ton (pun not intended) of experience with mid-scale hydrogenators, but I've seen use of 10-20L reactors before (here's Parr's version -- they can't be cheap) (Here's a small one for sale at LabX!) They seem to do fine, from what I've seen. There are issues with the bolts (always), but I think that's just a problem with hydrogenators, as opposed to a problem with this particular model. Minimum stir volume/agitation issues can arrive, of course. Cleaning is a bear, but Milkshake probably knows that anyway. Oh, and I don't think there's a window.

Readers, what is your experience? 

27 comments:

  1. Bring the MoviesMay 23, 2014 at 1:56 PM

    Wippin' up a lot of Crisco?

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  2. This is very nice of you, Chemjobber, thank you for writing the post!

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  3. that pun was totally intended, don’t make any apologies.

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  4. Probably have considered already but unless this equipment is anticipated to be used frequently in future would a purchase be worth the investment as short term fix? If already have one using a conventional 2L Shaker apparatus may be viable option because can indeed speed up reactions, with possibly to run more concentrated and with using only two bottles do trade off then can run multiple batches a day. I have had to do this repetitive mode when faced with "in between" scale to progress a project until demand was sufficient to get into the plants dedicated hydrogenation facility where smallest reactor I recall was a 5 gallon vessel (but could handle down to like just over 2 gallons). Alternatively I know there are a number of contract houses out there that likely have the suitable capability thus could outsource the particular step and work that way albeit timeliness may suffer unless find one in vicinity.

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  5. A few jobs ago, I ran quite a few kilo-scale hydrogenations using a 10L standing Parr reactor like Chemjobber linked in his post. At the time, the company owned a "well-loved" reactor, and maintained a winch next to it to move the (hundred of pounds) lid assembly off for cleaning.

    I recall looking through sites similar to LabX for these Parr reactors, and, to my great surprise, coming by many second-hand for 2-4k. Certainly worth a try, especially if they come partly decommissioned / decontaminated (through, if I recall, you'll spend the better part of a day flushing the system with water and methanol anyway, to remove the caked-on catalyst deposits!)

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  6. At the low pressures you are interested in, perhaps you do not need a shaker. I have very limited experience - but know of folks who did slightly higher pressures in a 20L glass vessel with stirring capability. This may give you more scale capability for other reactions as well.

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  7. 3 bar is ~45 psi, and a beer keg is rated up to at least 125.... Why not just improvise with a keg? Pressurize it and toss it on some ball mill rollers for mixing, and you are golden.

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    1. Exactly what I was thinking: 5 gallon Cornelius keg, and big paint shaker like they have in Home Depot. Probably could rig the whole thing for less than $300 plus the hydrogen tank. You think hydrogen embrittling could become a problem, for a one day run at 100psi?

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    2. I think (with proper safety precautions), it would be worth the risk for ~$500, and then if it doesn't work out (or takes out a wall, you go with the Parr apparatus.

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    3. Somehow I have the feeling that we will be reading about this adventure on the safety page of C&E News...

      I had a microbiology professor tell me that the hydrogen mixture he was using to culture some bacteria was "explosion proof". I challenged him, he decided to demonstrate and the campus police (across the street) thought that the SDS had bombed the campus.

      See also Hindenburg.

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    4. Good point Oldnuke. CJ & CJ readers/commenters would never get over it if a posting on the site for advice ended with RIP Milkshake!

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    5. or RIP someone who read the postings with no ability to detect sarcasm.

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    6. Another thing to remember -- hydrogen leaks and their resulting fires are difficult to detect. H2 burns with a colorless flame and it is HOT.

      I work in the utility industry -- we had hydrogen-cooled generators (500 MW). One day we had a leak -- after some initial confusion, I found it by holding a broom in front of me. When it caught fire, we'd found our problem (same tactic with superheated steam leaks).

      Scary stuff.

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    7. You're reminding me of one of my favorite passages in "The Hunt for Red October", about a sub's cook who used steam to clean off his pans... (and also about looking for leaks with a broom)

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    8. 1) "the pans may be safe to use in a hundred years or so". It reminds me of Clancy's aphorism that "Every ship can be a minesweeper. Once."

      2) A microbiology lab + insufficient care with hydrogen = http://pipeline.corante.com/archives/2010/06/30/how_not_to_do_it_hydrogen_gas_mixtures.php

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    9. Its only one day and 45 psi. I would not worry. But just to be sure, do it in a well-ventilated room out of the way. I've improvised sketchier.

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    10. My boss has found a spare keg (17 Liter volume) for our solvent purification station, rated to 3 bars, made of nonferromagnetic stainless steel (A big Sm-Co magnetic stirbar on IKA stirplate makes a nice vortex with 9 liters of water inside the keg) and the keg lid even gas a sparge tube and all the necessary Swagelock connections so I think we will give it a pressure test, starting with nitrogen first, and then proceed with some less valuable test material for the first run. I will let you know about the outcome of our keg hydrogenation, if I still have enough eyes and fingers left.

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    11. How did the keg hydrogenation turn out? We have a similar need and this seems like a good system.

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    12. We did not go ahead with a large scale process because the company changed the project priorities - so it is less urgent now, and I have other things to do... But if we need to hydrogenate a kilo amount of polymer again, I will try the keg for sure.

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  8. maybe use a very long extension cord with a switched electrical outlet to turn on the jimmied apparatus while no one is near it or its walls..

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  9. one thing about parr, is that the electrical is anti spark. A beer keg/paint shaker might produce sparks.

    You can get little tanks of hydrogen if you want to isolate it from a normal sized tank. You can also get fire safe vented cabinets for hydrogen tanks.

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  10. use a standard glass vessel outfitted with a thick mil latex bag (black, soccer ball size sold by aldrich) and H2 line. Then use the baloon as both a visual manometer and a hydrogen reserve. Reinflate when near depleted. This simple set up will substitute any fancy or high pressure system there are... Done it time and time again.

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    1. For those thinking about working (or playing) with hydrogen, take a look at this: http://www.h2incidents.org/

      Hundreds of examples why hydrogen is not always your friend!

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    2. The link works fine for me in Chrome....

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    3. Huh, wasn't working for me right after you posted it. Works fine now -- thanks!

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