Technology

CN102267859B describes Ruihua's technology for alkylation reaction of benzene with crude ethylene (high-concentration ethylene gas) in liquid phase for the production of ethylbenzene.

The process allows the existence of a small amount of other heavy olefins in concentrated ethylene dry gas, does not increase the impurity content in ethylbenzene in the alkylation product of the heavy olefins, allows the content of the heavy olefins such as propylene to be within 10 percent, preferably 1-1000 ppm, does not need pretreatment, can recover propylbenzene generated by alkylation in a separation part, and can further refine this product to obtain isopropylbenzene (cumene).

The attached image depicts the corresponding process design according to: 

1. Absorption tower
2. liquid phase alkylation reactor
3. protective reactor
4. heating furnace
5. gas phase alkylation reactor
6. stabilization tower
7. tail gas absorption tower
8. benzene recovery tower
9. ethylbenzene recovery tower
10. propylbenzene recovery tower
11. isopropylbenzene refining tower
12. ethylbenzene recovery tower
13. transalkylation reactor

Operational details are provided in the referenced document in the disclosure of the invention, in Example 1 and in the claims, which are simplified according to:

1. Dividing raw material concentrated ethylene dry gas into a plurality of strands enabling the plurality of strands of concentrated ethylene dry gas to enter a plurality of absorption towers and divide the raw material benzene into two strands;
2. a first strand of concentrated ethylene dry gas entering a first absorption tower, and an absorbent at the top of the first absorption tower is a strand of raw material benzene and a discharge material of an alkylation reaction; the reaction material after impurity removal enters a first catalyst reaction bed layer of a liquid phase alkylation reactor, and liquid phase alkylation reaction is carried out under the action of a molecular sieve catalyst;
3. after the reaction discharge generated after the reaction of the first catalyst reaction bed layer is subjected to heatexchange and temperature reduction; a second ethylene-rich liquid material formed by a second stream of the dry ethylene-rich gas material from the second absorption tower enters a second catalyst reaction bed layer of the liquid phase alkylation reactor for liquid phase alkylation reaction, and a second gas phase material from the second absorption tower is heated and then enters the gas phase alkylation reactor for reaction treatment;
4. separating two materials from a reaction discharge material II generated after the reaction of the second catalyst reaction bed layer after heat exchange and temperature reduction, wherein the first material returns to the top of the second absorption tower to be used as an absorbent of the second absorption tower, and the second material enters a third absorption tower to be used as an absorbent of the third absorption tower;
5. carrying out corresponding reaction and distribution on a third and later strands of the dry ethylene dry gas materials according to the step 3. and the step 4., wherein the tail material formed by the last strand of the materials after alkylation reaction is also divided into two strands, the first strand of the materials returns to the top of the last absorption tower to be used as an absorbent of the absorption tower, and the second strand of the materials enters a benzene recovery tower;
6. feeding the distilled benzene in the benzene recovery tower back to a reaction system of raw material benzene in a liquid phase mode, and simultaneously extracting a material rich in ethylbenzene from the benzene recovery tower and feeding the material into an ethylbenzene recovery tower;
7. an ethylbenzene distillate is formed in the ethylbenzene recovery tower, other produced substances are sent into a propyl benzene recovery tower, a propyl benzene byproduct distillate is formed at the tower top of the propyl benzene recovery tower, and the produced substances formed at the tower bottom of the propyl benzene recovery tower enter a polyethylbenzene recovery tower;
8. and forming a distillate comprising benzene, diethylbenzene and a small amount of triethylbenzene components at the top of the tower in a polyethylbenzene recovery tower, enabling the distillate to enter a tail gas recovery tower to recover the benzene therein, then enabling the distillate to enter a transalkylation reactor, carrying out transalkylation reaction with a strand of raw material benzene, and enabling a discharge material formed after the transalkylation reaction to enter a benzene recovery tower.
9. In order to further recover benzene to form recycled benzene for utilization and improve the recovery rate of ethylene, the discharged material after reaction treatment of the gas-phase alkylation reactor enters a stabilizing tower after cooling treatment, the gas phase separated from the top of the stabilizing tower enters a tail gas recovery tower to 7/14recover the benzene therein and then is discharged as fuel, and the liquid phase separated from the stabilizing tower enters a benzene recovery tower.

Source: 和成刚 et al., CN107827692B, Filling Date 28^th Apr 2017, Method for producing ethylbenzene by using high-concentration ethylene gas, Assigned to Changzhou Ruihua Chemical Eng & Tech Co ltd.