Separation of ethylbenzene and toluene
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The boiling points of ethylbenzene and xylene are relatively close. Are there any other methods for separating them apart from conventional distillation? I found that Liaoning Zhongke has installed a corresponding system – are there anyone who is familiar with this?
It seems that a moving bed can be used to achieve separation
This post was last edited by Fred_bj on 2009-10-28 00:07. The established technology for separating ethylbenzene from xylene is superrectification. Three towers in series, with nearly 300 trays, and a high reflux ratio as well (early sieve tray tower technology; nowadays high-efficiency packed towers are used, so it’s likely that a three-tower process will no longer be necessary). Both the investment cost and operating cost are very high. Adsorption separation can be used to isolate p-xylene or m-xylene from the four isomers of C8 aromatics (ethylbenzene, p-xylene, m-xylene, o-xylene). There is no direct separation of ethylbenzene. Perhaps two adsorption separation units can be connected in series: the first unit separates m-xylene, and the raffinate is sent to the second adsorption separation unit to separate p-xylene. In this way, the main components of the raffinate should be ethylbenzene and o-xylene, which can then be separated through ordinary distillation. However, due to the recovery rate limitations of adsorption separation, it is difficult to obtain ethylbenzene products that are suitable as raw materials for styrene using this approach. Due to the relatively low freezing point of ethylbenzene, crystallization may be employed to separate xylene, thereby obtaining high-quality ethylbenzene product. Further research is needed (it is likely difficult to ensure both purity and a reasonable recovery rate simultaneously).