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Houngan
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Hydrogenation
Hi,
I am planning on doing some hydrogenation and I have a source of hydrogen and a catalyst but I neet to flush the vessel with an inert gas first.
I'm not to sure about aquiring cylinder nitrogen, so I had a thought of using carbon dioxide from dry ice?
What do people use in this case?
I am in Australia so the rules may be different but any suggestions would be greatly appreciated.
The spice must flow.
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bfesser
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Is your hydrogen prohibitively expensive? If not, flush with H<sub>2<?sub>.
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unionised
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Because you don't want a mixture of air, hydrogen and a catalyst.
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Mailinmypocket
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Quote: Originally posted by Houngan  | Hi,
I am planning on doing some hydrogenation and I have a source of hydrogen and a catalyst but I neet to flush the vessel with an inert gas first.
I'm not to sure about aquiring cylinder nitrogen, so I had a thought of using carbon dioxide from dry ice?
What do people use in this case?
I am in Australia so the rules may be different but any suggestions would be greatly appreciated. |
Go to a winemaking store or a well stocked liquor store... They very often sell cans of argon (they look like cans of hair spray, low pressure). It is
used to spray into open bottles of wine to create an inert blanket over the wine to prevent oxidation, and shitty tasting wine. Not super cheap,
around 8$, but if you want some argon that requires no cylinders, regulators and such... It's a good source 
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Houngan
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Cheers everyone!
Yeah I had though of flooding it with H2 above the ignition concentration. That would probably be my best option.
I might have to look into that "Argon in a Can"TM sounds neat!
Thanks again
The spice must flow.
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bananaman
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Why not simply attach your vessel to a vacuum pump, and have it evacuate the entire vessel before introducing the H2 gas?
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Nicodem
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| Quote: Originally posted by Houngan | | Yeah I had though of flooding it with H2 above the ignition concentration. That would probably be my best option. |
That would be very dangerous. Hydrogen and air should never be mixed above a mixture containing Pd-C or other hydrogenation catalysts. You should
follow the safety protocol and either flush the air by an inert gas or by vacuum.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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ash
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The best option people use to apply is making a mixture of catalyst, your substrate and solvent (methanol, isnt it?), then vacuumizing the flask till
methanol starts to boil, then fill the flask with hydrogen. Procedure can be repeated.
I did it personally several times, works perfectly.
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zed
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Indeed. Vacuum is a widely available and inexpensive purging agent. My personal favorite.
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luckybot
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What about propane?
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bananaman
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What do you mean by propane?
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gsd
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What s/he means by propane is why not use cooking gas to flush the hydrogenator.
Though it certailnly is an "out of box" suggestion for home chemist, personally I don't think it is worth the risk. In absence of an inert gas,
vacuum is the way to go.
Gsd
[Edited on 21-2-2013 by gsd]
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zed
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Also, propane may contain sulfides. A poison for certain catagories of catalyst.
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497
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| Quote: |
Also, propane may contain sulfides
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But butane doesn't 
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killer_lapin
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actualy butane contain sulfides too, otherwise you couldn't smell it.
[Edited on 23-2-2013 by killer_lapin]
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Diablo
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They sell extra pure butane for certain extractions.
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gsd
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Yeah but if you have to buy such an exotic gas just to flush an apparatus, you might as well buy humble N2.
Gsd
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ash
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another home speed maker? sick of them
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Doc B
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Oi skippy, get your arse down to Bunnings stat. In the welding section you'll find Nitrogen, Argon, CO2, and other small to large cash and carry basis
gasses suitable with regulators et al req.
Now spill it, where the fuck are you getting dry ice here? I've been recycling fire extinguishers but that's fairly crap.
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zed
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An Ice cream supplier might be able to help you. Not a problem anymore in the U.S..
Every supermarket has it.
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luckybot
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What are you talking about?
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Houngan
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Cool, vacuum pump is the way to go then.
I had thought of that but was concerned that I would suck the contents out of my vessel.
I guess ill have to not suck too hard then (I don't plan on being the pump, just to clarify) 
Thanks again.
The spice must flow.
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497
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In the US butane meant for refilling lighters doesn't smell. Just saying...
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Nicodem
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Confined mixtures of butane and air can explode when ignited. (seems like some posters are unaware of this)
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497
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Considering the upper explosive limit is 8.4% you'd really have to screw up the "flushing" thing to have that problem... Always good to be careful
though. I suppose there's always difluoroethane from those cans of "dust off" too.
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