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Manufacturing of Styrene

Ethylbenzene is produced commercially by alkylating benzene with ethylene using an acidic catalyst, with newer technologies using synthetic zeolites installed in fixed-bed reactors to catalyze the reaction in the liquid phase. Ethylbenzene and styrene units are installed together to integrate the exothermic alkylation reaction with the endothermic dehydrogenation to styrene. While some ethylbenzene was previously recovered from mixed xylenes by fractionation, this practice has been largely discontinued due to high costs and small economies of scale compared to conventional alkylation routes.

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Nornadiahnadhirah MdNadzri
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79 views1 page

Manufacturing of Styrene

Ethylbenzene is produced commercially by alkylating benzene with ethylene using an acidic catalyst, with newer technologies using synthetic zeolites installed in fixed-bed reactors to catalyze the reaction in the liquid phase. Ethylbenzene and styrene units are installed together to integrate the exothermic alkylation reaction with the endothermic dehydrogenation to styrene. While some ethylbenzene was previously recovered from mixed xylenes by fractionation, this practice has been largely discontinued due to high costs and small economies of scale compared to conventional alkylation routes.

Uploaded by

Nornadiahnadhirah MdNadzri
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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2 Manufacturing
Commercially, almost all ethylbenzene (> 99 %) is produced by alkylating benzene with
ethylene, except for a very small fraction that is recovered from mixed C8 aromatics
(xylenes) by superfractioning.
Ethylbenzene and styrene units are almost always installed together, with matching
capacities. In a typical ethylbenzene-styrene complex, energy economy is realized by
advantageously integrating the energy flows of the two units. The alkylation is exothermic,
while the subsequent dehydrogenation to styrene is endothermic.
The reaction of benzene and ethylene takes place on an acidic catalyst (Lewis acids):
C6H6 + CH2=CH2 C6H5CH2CH3
The newest technologies utilize synthetic zeolites installed in fixed-bed reactors to catalyze
the alkylation in the liquid phase. Another proven route uses narrower-pore synthetic
zeolites, also installed in fixed-bed reactors, to effect the alkylation in the vapour phase. A
considerable quantity of ethylbenzene is still produced by alkylation with homogeneous
aluminum chloride catalyst in the liquid phase, though the recent trend in the industry has
been to retrofit such units with zeolite technology.
Several facilities built in the United States, Europe and Japan during the 1960s recovered
ethylbenzene by fractionation of mixed xylenes (C8 aromatics) produced mainly in refinery
catalytic reforming units. Mixed-xylenes capacity worldwide was 36 million tonnes in 2002.
This practice has largely been discontinued, due to poor economics that result from high
energy and investment costs, as well as small economies of scale (mixed xylenes only
contain about 20 % ethylbenzene) in comparison to the conventional alkylation routes.

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