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Impurities Exist In Dehydration Of Alcohol


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#1 dumbcute

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Posted 11 March 2008 - 09:47 AM

my tuition teacher gave me this question:
ethene is prepared from dehydration of ethnol using concentrated sulphuric acid. which of the following exists as impurities?

answer given is ether..

can someone please explain the reason?? unsure.gif

#2 djack77494

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Posted 12 March 2008 - 12:59 PM

You don't tell us which ether is an impurity, nor do you tell us whether it is an impurity in the feed or the product stream. Assuming pure ethanol is treated with sulfuric acid, I would expect that an ether could be produced as follows:

CH3CH2OH + CH3CH2OH -----> CH3CH2-O-CH2CH3 + H2O

That is, two ethanol molecules are dehydrated to produce diethyl ether and water. (I think the name diethyl ether would be consider obsolete today, and that compound is probably more properly called ethoxyethane.)

What is a tuition teacher??

Doug

#3 Padmakar Katre

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Posted 30 March 2008 - 02:43 AM

Dear,
I haven't heard about the dehydration of Alcohol by using H2SO4 to ethylene but I worked with a plant where we had ethanol dehydration to ethene by using the superheated steam as the reaction is an endothermic and the energy required is supplied in the form of the superheated steam. The main imurities which we used to get in the sample analysis of the Ethene are as below
1. Acetaldehyde which is nothing but the cracking product of the ethanol at a very high reactor inlet temperature. (Here in this case the Steam to Etanol ratio plays the key role)
2. The ethanol if its 100 % pure then you will not find the cracking products of higher alcohols but if you have the higher alcohols present in the main ethanol feed.
3. The merceptans
4. I had a spec of the ethanol feed like
Ethanol 96.5 % H2O 2.5% and Acetone less than 10 ppm and heavier alcohols around 1 % in the reactor feed and the ethylene produced has a purity of the 99.8 %( all are mol %).
Any further information you need please don't hesitate to ask.

#4 prem raj

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Posted 30 July 2009 - 10:59 PM

Dear Padmakar,


Im a final year student. My group and I are doing a design project to design an ethylene plant, however we are producing it from the dehydration of ethanol. We have tried finding infomation for the dehydration process in industries but cannot find anything online. We only found bits and pieces of information that we've tried to put together.

We would greatly appreciate it if you can tell us where we can find information on this process, like a process description, process flow diagram (PFD), and kinetic data, temperatures and pressures.

Also...just out of curiousity, is there any particular reason why there is no information on this process...other than ethanol is worth more, or ethylene from natural gas is cheaper. My email address is per_rem@yahoo.com. Besides, another problem is my feedstock price is more expensive than the product price in Malaysia

#5 Padmakar Katre

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Posted 31 July 2009 - 11:25 AM

Dear I had replied to your post in another similar thread.




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