Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  
Author: Subject: Hydrogenation
Houngan
Harmless
*




Posts: 16
Registered: 19-1-2012
Location: Space
Member Is Offline

Mood: Regioregular

[*] posted on 18-2-2013 at 07:12
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.
View user's profile View All Posts By User
bfesser
Resident Wikipedian
*****




Posts: 2114
Registered: 29-1-2008
Member Is Offline

Mood: No Mood

[*] posted on 18-2-2013 at 12:06


Is your hydrogen prohibitively expensive? If not, flush with H<sub>2<?sub>.



View user's profile View All Posts By User
unionised
International Hazard
*****




Posts: 4626
Registered: 1-11-2003
Location: UK
Member Is Offline

Mood: No Mood

[*] posted on 18-2-2013 at 12:35


Because you don't want a mixture of air, hydrogen and a catalyst.
View user's profile View All Posts By User
Mailinmypocket
International Hazard
*****




Posts: 1349
Registered: 12-5-2011
Member Is Offline

Mood: No Mood

[*] posted on 18-2-2013 at 12:40


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 :)
View user's profile View All Posts By User
Houngan
Harmless
*




Posts: 16
Registered: 19-1-2012
Location: Space
Member Is Offline

Mood: Regioregular

[*] posted on 18-2-2013 at 15:44


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.
View user's profile View All Posts By User
bananaman
Harmless
*




Posts: 19
Registered: 29-1-2013
Member Is Offline

Mood: No Mood

[*] posted on 18-2-2013 at 23:39


Why not simply attach your vessel to a vacuum pump, and have it evacuate the entire vessel before introducing the H2 gas?
View user's profile View All Posts By User
Nicodem
Super Moderator
*******




Posts: 4230
Registered: 28-12-2004
Member Is Offline

Mood: No Mood

[*] posted on 19-2-2013 at 09:07


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!
View user's profile View All Posts By User
ash
Harmless
*




Posts: 8
Registered: 19-2-2013
Member Is Offline

Mood: No Mood

[*] posted on 19-2-2013 at 10:03


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.
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 2201
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Online

Mood: Semi-repentant Sith Lord

[*] posted on 20-2-2013 at 18:00


Indeed. Vacuum is a widely available and inexpensive purging agent. My personal favorite.
View user's profile View All Posts By User
luckybot
Harmless
*




Posts: 17
Registered: 10-2-2013
Member Is Offline

Mood: No Mood

[*] posted on 20-2-2013 at 18:35


What about propane?
View user's profile View All Posts By User
bananaman
Harmless
*




Posts: 19
Registered: 29-1-2013
Member Is Offline

Mood: No Mood

[*] posted on 20-2-2013 at 21:50


Quote: Originally posted by luckybot  
What about propane?


What do you mean by propane?
View user's profile View All Posts By User
gsd
International Hazard
*****




Posts: 847
Registered: 18-8-2005
Member Is Offline

Mood: No Mood

[*] posted on 20-2-2013 at 22:02


Quote: Originally posted by bananaman  
Quote: Originally posted by luckybot  
What about propane?


What do you mean by propane?


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]
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 2201
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Online

Mood: Semi-repentant Sith Lord

[*] posted on 21-2-2013 at 16:41


Also, propane may contain sulfides. A poison for certain catagories of catalyst.
View user's profile View All Posts By User
497
International Hazard
*****




Posts: 778
Registered: 6-10-2007
Member Is Offline

Mood: HSbF6

[*] posted on 22-2-2013 at 14:34


Quote:

Also, propane may contain sulfides


But butane doesn't ;)




A word to the wise: NEUROFEEDBACK

http://citizenworks.org/corp/dg/s2r1.pdf
http://www.newscientist.com/mobile/article/mg21228354.500-re...
http://www.shadowstats.com/article/no-414-hyperinflation-spe...

"To expose a 15 Trillion dollar ripoff of the American people by the stockholders of the 1000 largest corporations over the last 100 years will be a tall order of business."
Buckminster Fuller

"No problem can be solved from the same level of consciousness that created it."
Albert Einstein
View user's profile View All Posts By User
killer_lapin
Harmless
*




Posts: 47
Registered: 23-7-2010
Location: Qc, CAN
Member Is Offline

Mood: No Mood

[*] posted on 22-2-2013 at 16:02


actualy butane contain sulfides too, otherwise you couldn't smell it.

[Edited on 23-2-2013 by killer_lapin]
View user's profile View All Posts By User
Diablo
Hazard to Others
***




Posts: 113
Registered: 17-9-2011
Member Is Offline

Mood: Autodidactic

[*] posted on 22-2-2013 at 18:49


They sell extra pure butane for certain extractions.
View user's profile View All Posts By User
gsd
International Hazard
*****




Posts: 847
Registered: 18-8-2005
Member Is Offline

Mood: No Mood

[*] posted on 22-2-2013 at 23:26


Yeah but if you have to buy such an exotic gas just to flush an apparatus, you might as well buy humble N2.

Gsd
View user's profile View All Posts By User
ash
Harmless
*




Posts: 8
Registered: 19-2-2013
Member Is Offline

Mood: No Mood

[*] posted on 23-2-2013 at 04:49


Quote: Originally posted by luckybot  
What about propane?

another home speed maker? sick of them
View user's profile View All Posts By User
Doc B
Hazard to Others
***




Posts: 107
Registered: 5-4-2012
Member Is Offline

Mood: No Mood

[*] posted on 23-2-2013 at 06:04


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.
View user's profile View All Posts By User
zed
International Hazard
*****




Posts: 2201
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Online

Mood: Semi-repentant Sith Lord

[*] posted on 23-2-2013 at 15:49


An Ice cream supplier might be able to help you. Not a problem anymore in the U.S..

Every supermarket has it.
View user's profile View All Posts By User
luckybot
Harmless
*




Posts: 17
Registered: 10-2-2013
Member Is Offline

Mood: No Mood

[*] posted on 23-2-2013 at 15:50


Quote: Originally posted by ash  
Quote: Originally posted by luckybot  
What about propane?

another home speed maker? sick of them

What are you talking about?
View user's profile View All Posts By User
Houngan
Harmless
*




Posts: 16
Registered: 19-1-2012
Location: Space
Member Is Offline

Mood: Regioregular

[*] posted on 25-2-2013 at 05:03


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) :P

Thanks again.




The spice must flow.
View user's profile View All Posts By User
497
International Hazard
*****




Posts: 778
Registered: 6-10-2007
Member Is Offline

Mood: HSbF6

[*] posted on 26-2-2013 at 21:36


In the US butane meant for refilling lighters doesn't smell. Just saying...



A word to the wise: NEUROFEEDBACK

http://citizenworks.org/corp/dg/s2r1.pdf
http://www.newscientist.com/mobile/article/mg21228354.500-re...
http://www.shadowstats.com/article/no-414-hyperinflation-spe...

"To expose a 15 Trillion dollar ripoff of the American people by the stockholders of the 1000 largest corporations over the last 100 years will be a tall order of business."
Buckminster Fuller

"No problem can be solved from the same level of consciousness that created it."
Albert Einstein
View user's profile View All Posts By User
Nicodem
Super Moderator
*******




Posts: 4230
Registered: 28-12-2004
Member Is Offline

Mood: No Mood

[*] posted on 27-2-2013 at 07:26


Confined mixtures of butane and air can explode when ignited. (seems like some posters are unaware of this)
View user's profile View All Posts By User
497
International Hazard
*****




Posts: 778
Registered: 6-10-2007
Member Is Offline

Mood: HSbF6

[*] posted on 1-3-2013 at 08:59


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.



A word to the wise: NEUROFEEDBACK

http://citizenworks.org/corp/dg/s2r1.pdf
http://www.newscientist.com/mobile/article/mg21228354.500-re...
http://www.shadowstats.com/article/no-414-hyperinflation-spe...

"To expose a 15 Trillion dollar ripoff of the American people by the stockholders of the 1000 largest corporations over the last 100 years will be a tall order of business."
Buckminster Fuller

"No problem can be solved from the same level of consciousness that created it."
Albert Einstein
View user's profile View All Posts By User
 Pages:  1  

  Go To Top