Method and system for treatment of spent chloroaluminate ionic liquid catalyst and alkaline wastewater

Patent metadata

Field	Value
Publication number	US-11426702-B2
Application number	US-202017006723-A
Country	US
Kind code	B2
Filing date	Aug 28, 2020
Priority date	Mar 1, 2018
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A method and a system for treatment of a spent chloroaluminate ionic liquid catalyst and an alkaline wastewater, where the method includes: 1) mixing the catalyst with a concentrated brine for hydrolysis reaction until residual activity of the catalyst is completely eliminated, to obtain an acidic hydrolysate and an acid-soluble oil; 2) mixing the acidic hydrolysate with an alkaline solution containing the alkaline wastewater for neutralization reaction until this reaction system becomes weak alkaline, to obtain a neutralization solution; 3) fully mixing the neutralization solution with a flocculant, carrying out sedimentation and separation, collecting the concentrated brine at an upper layer for reuse in the hydrolysis reaction, and collecting concentrated flocs at a lower layer; 4) dehydrating the concentrated flocs to obtain concentrated brine for reuse into the hydrolysis reaction, and collecting a wet solid slag; and 5) drying the wet solid slag to obtain a dry solid slag.

First claim

What is claimed is:

1. A method for treatment of a spent chloroaluminate ionic liquid catalyst and an alkaline wastewater, comprising the following steps:
1) mixing the spent chloroaluminate ionic liquid catalyst with a concentrated brine for hydrolysis reaction until a residual activity of the spent chloroaluminate ionic liquid catalyst is completely eliminated, and separating products of the hydrolysis reaction to obtain an acidic hydrolysate and an acid-soluble oil respectively;
2) mixing the acidic hydrolysate with an alkaline solution containing the alkaline wastewater for neutralization reaction until this reaction system becomes weak alkaline, to obtain a concentrated brine and a neutralization solution containing metal hydroxide flocs;
3) fully mixing the neutralization solution with a flocculant and implementing sedimentation and separation to obtain the concentrated brine at an upper layer and concentrated flocs at a lower layer, collecting the concentrated brine at the upper layer and reusing it in the hydrolysis reaction, and meanwhile collecting the concentrated flocs at the lower layer;
4) dehydrating the concentrated flocs to separate the concentrated brine from metal hydroxide, collecting the metal hydroxide as a wet solid slag, and reusing the concentrated brine obtained by dehydrating into the hydrolysis reaction; and
5) drying the wet solid slag to obtain a dry solid slag.

2. The method according to claim 1 , wherein in step 1), a content of sodium chloride in the concentrated brine is 15-22 wt %, and a feed volume ratio of the spent chloroaluminate ionic liquid catalyst to the concentrated brine is 1: (50-60).

3. The method according to claim 1 , wherein in step 1), the hydrolysis reaction is carried out in a plug flow packed bed reactor, and the plug flow packed bed reactor is filled with structured packing.

4. The method according to claim 3 , wherein the structured packing has a porosity of 0.95-0.97 m 3 /m 3 , and a specific surface area of 300-500 m 2 /m 3 .

5. The method according to claim 3 , wherein the plug flow packed bed reactor has an airspeed of 0.25-0.5 h −1 .

6. The method according to claim 3 , wherein the structured packing is a Y-shaped corrugated orifice structured packing; a material of the structured packing is polyethylene, polyvinyl chloride or polyvinylidene fluoride.

7. The method according to claim 1 , wherein in the step of the spent chloroaluminate ionic liquid catalyst being mixed with the concentrated brine to carry out hydrolysis reaction, when a pH of the acidic hydrolysate is basically stabilized at 2.5-2.8, the hydrolysis reaction is completed.

8. The method according to claim 1 , wherein in step 2), the neutralization reaction is carried out in a complete-mixing flow reactor, and the complete-mixing flow reactor has an airspeed of 1-2 h −1 .

9. The method according to claim 1 , wherein in step 2), a pH value of the neutralization solution is 8.0-8.5.

10. The method according to claim 1 , wherein in step 3), the flocculant is an anionic polyacrylamide, the anionic polyacrylamide has a relative molecular weight of 6-18 million, and a charge density of 10-40%.

11. The method according to claim 10 , wherein the flocculant is added in an amount of 20-30 g per ton of the neutralization solution, and time of the sedimentation and separation is 2-3 hours.

12. The method according to claim 1 , wherein the spent chloroaluminate ionic liquid catalyst is a spent catalyst produced by using a chloroaluminate ionic liquid to catalyze C4 to produce an alkylated oil; the alkaline wastewater is an alkali washing wastewater produced by using a chloroaluminate ionic liquid to catalyze C4 to produce an alkylated oil.

13. A system for implementing the method according to claim 1 , comprising:
a hydrolysis reactor, a neutralization reactor, a flocculation sedimentation system, a mechanical dehydration device and a drying device;
the hydrolysis reactor is configured to mix the spent chloroaluminate ionic liquid catalyst with the concentrated brine for hydrolysis reaction;
the neutralization reactor is connected to the hydrolysis reactor, and is configured to mix the acidic hydrolysate generated by the hydrolysis reaction with the alkaline solution containing the alkaline wastewater for neutralization reaction;
the flocculation sedimentation system is connected to the neutralization reactor, and is configured to fully mix the neutralization solution generated by the neutralization reaction with the flocculant and implement sedimentation and separation;
the mechanical dehydration device is connected to the flocculation sedimentation system, and is configured to perform a dehydration treatment on the concentrated flocs formed by the sedimentation and separation; and
the drying device is connected to the mechanical dehydration device, and is configured to dry the wet solid slag formed by the dehydration treatment.

14. The system according to claim 13 , wherein the hydrolysis reactor comprises a shell; an annular oil collecting groove, a water distributor for distributing the concentrated brine and a material distributor for distributing the spent chloroaluminate ionic liquid catalysts are sequentially arranged on an upper part of the shell from top to bottom; a packing support bracket for supporting a packing is provided at a lower part of the shell; an exhaust port is provided at the top of the shell; an oil outlet, a water inlet and a feed inlet are provided on a side wall of the shell, the oil outlet is in communication with the annular oil collecting groove, the water inlet is in communication with the water distributor, the feed inlet is in communication with the material distributor; and a liquid outlet is provided at a bottom of the shell.

15. The system according to claim 13 , wherein the neutralization reactor is a complete-mixing flow reactor; the neutralization reactor comprises a shell; a water distributor for distributing the alkaline solution and a material distributor for distributing the acidic hydrolysate are sequentially arranged at an upper part of the shell from top to bottom; a side-entry agitator is provided in the middle of the shell; an exhaust port is provided at the top of the shell; an alkali inlet and a liquid inlet are provided on a side wall of the shell, the alkali inlet is in communication with the water distributor, the liquid inlet is in communication with the material distributor; and a liquid outlet is provided at the bottom of the shell.

16. The system according to claim 14 , wherein the water distributor comprises a water distribution main pipe, and a plurality of parallel water distribution branch pipes arranged at equal intervals are respectively provided on both sides of the water distribution main pipe, a plurality of water distribution holes are distributed at the bottom of each water distribution branch pipe, and a total opening area of the water distribution holes accounts for more than 1% of a cross-sectional area of the reactor.

17. The system according to claim 14 , wherein the material distributor comprises a material distribution main pipe, a plurality of semicircular material distribution branch pipes arranged concentrically and at equal intervals are respectively provided on both sides of the material distribution main pipe, a plurality of material distribution holes are distributed at the bottom of each semicircular material distribution branch pipe, and a total opening area of the material distribution holes accounts for more than 2% of a cross-sectional area of the reactor.

18. The

Assignees

• Univ China Petroleum Beijing

Inventors

• Chen Chunmao
• Liu Zhichang
• Yi Zhongjin
• Zhang Rui
• Liang Jiahao
• Meng Xianghai
• Liu Haiyan
• Xu Chunming
• Wang Qinghong

Classifications

• C02F2001/007

  Processes including a sedimentation step · CPC title

• C02F1/66

  by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) · CPC title

• B01J19/18

  Stationary reactors having moving elements inside (B01J19/08, B01J19/26 take precedence) · CPC title

• C02F11/12

  by de-watering, drying or thickening · CPC title

• C02F1/56

  Macromolecular compounds · CPC title