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Author: Subject: propane to propene
vmelkon
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[*] posted on 10-1-2013 at 07:11
propane to propene


Hi,
From what I saw on wikipedia, it is possible to convert propane into propene + H2. Has anyone tried this?
I imagine if you pass propane over some hot Al2O3 or SiO2 (400 - 500 C), it would dehydrogenate.
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Nicodem
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[*] posted on 10-1-2013 at 11:40


Quote: Originally posted by vmelkon  
I imagine if you pass propane over some hot Al2O3 or SiO2 (400 - 500 C), it would dehydrogenate.

Why would it? What is the reference?




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vmelkon
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[*] posted on 10-1-2013 at 12:53


1. This one says chromia-alumina catalyst which I guess means Cr2O3 and Al2O3
http://www.ehow.com/how-does_5272515_propane-dehydrogenation...

2. This one says the same thing : chromia-alumina
http://primaryinfo.org/1-projects/Propane%20Dehydrogenation....

3. This one says Cr2O3 but they don't mention propane
http://en.wikipedia.org/wiki/Dehydrogenation
says that
"Dehydrogenation of paraffins and olefins — paraffins such as n-pentane and isopentane can be converted to pentene and isoprene using chromium (III) oxide as a catalyst at 500 °C."

4. Cracking hydrocarbons. The catalyst is pumice.
http://www.youtube.com/watch?v=ZYyKUePdC2Y

so that makes me wonder whether Al2O3 or SiO2 would work.
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bbartlog
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[*] posted on 10-1-2013 at 14:59


Sounds impractical. Dehydration of isopropyl alcohol is just a massively easier route to propylene for the home experimenter. I know I've produced tens of grams inadvertently as a side product while synthesizing isopropyl chloride.



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[*] posted on 11-1-2013 at 09:31


Quote: Originally posted by vmelkon  
so that makes me wonder whether Al2O3 or SiO2 would work.

Just because alumina can be used as a solid support for the catalyst, it does not mean that it can work as a catalyst by itself. Carbon can be used as a solid support for palladium and such a combination is actually the most commonly used hydrogenation catalyst, yet it would be nonsense to expect the same hydrogenation catalysis from carbon alone. Catalyst supports have very important roles in catalysis, but they usually don't not have the catalytic role per se.

However, acidic alumina and silicagel can be used as acid catalysts for the vapor phase reactions catalyzed by acids (for example, the dehydration of 2-propanol to propene, etc.).




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