Hi there
Acetone can be derived by several means:
(1) Oxidation of cumene;
(2) dehydrogenation or oxidation of isopropyl alcohol;
(3) vapor phase oxidation of butane;
(4) by-product of synthetic glyerol production.
Industrially it is often produced by the catalytic dehydrogenation of
isopropyl alcohol. The kinetically controlled reaction (CH3)2OH ->
(CH3)2CO + H2
occurs in the vapor phase and is endothermic with a heat of reaction
equal to 62.9 kJ/mol. Side reactions are negligible at normal
operating conditions.
Here is an example design based on the steps involved in a typical
industrial process. The "reactor" is the vessel where the reaction
takes place.
- Fresh isopropyl alcohol is mixed with a recycled isopropyl alcohol
stream to form the reactor feed. (The recycle stream is an azeotropic
mixture of water and isopropyl alcohol recovered from the reactor
effluent at the end of the process.)
- The feed is preheated and vaporized in a reactor preheater utilizing
high pressure steam. (At the heat exchanger exit, the temperature
should be 234 C.)
- The feed then enters copper/metal oxide catalyst-filled tubes of a
shell and tube reactor. A molten salt stream flows through the shell
to further heat the feed and maintain the reactor at the desired
operating temperature of 350 C.
- A natural gas fired heater heats the recirculating salt stream from
357 C, upon exiting the reactor, to 407 C.
- Reactor effluent is cooled to 20 C by two heat exchangers requiring
cooling water (exit temperature equal to 45 C) and refrigerated water
utilities, respectively.
- Most of the hydrogen in the effluent is removed in a flash vessel.
Gaseous isopropyl alcohol and acetone that exit with the hydrogen are
recovered in a subsequent absorption step.
- Absorption occurs in a 3.2 meter packed column utilizing water as
the absorbing liquid.
- The gas leaving the absorber forms the product/hydrogen stream. The
liquid leaving the absorber is mixed with liquid from the flash and
sent to a 66 tray acetone recovery column.
- This column produces liquid acetone as the top product; hydrogen
recovered from the top is mixed with the hydrogen product from the
absorber. The bottom product is sent to a 19 tray isopropyl alcohol
recovery column. (Because isopropyl alcohol and water form a minimum
boiling azeotrope, the top product from this column is a liquid
mixture containing 88% isopropyl alcohol that is recycled to the
reactor feed. The bottom product is essentially pure water but
contains trace amounts of organics which require waste treatment.)
Unfortunately we cannot reproduce diagrams here, but you’ll find the
perfect diagram at (http://www2.cemr.wvu.edu/~wwwche/publications/projects/acetone/acetone-a.PDF)
This is a university paper asking for answers to a particular design
problem in the system, but it gives a very good overview of exactly
what you asked for, along with some diagrams. Chemical reactions, and
problems with the design.
I did three years of chemistry at university, and answering this
brought it all rushing back to me. Hope the answer helps.
Willie
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