Patent Application
20080091051
The present invention is further illustrated by the following examples with reference to the drawings, however, the present invention should not be restricted to these examples anyway.
The present invention provides a method for preparing bisphenol A (cf.
In the present invention, said reaction zone is an adiabatic fixed bed reactor, or two or more adiabatic fixed bed reactors arranged in series, and said rectification zone can be a rectification column with side draws, a combination of a flash drum and a rectification column, or other devices and processes capable of removing lights and water (cf.
In the first embodiment according to the present invention, said reaction zone includes two adiabatic fixed bed reactors arranged in series, said rectification zone is rectification column T (cf.
In another embodiment according to the present invention, said reaction zone comprises two adiabatic fixed bed reactors arranged in series, said rectification zone comprises flash drum V and rectification column T (cf.
The catalysts used in the following examples are Purolite CT-124 cation exchange resin (ex Purolite International Ltd.).
The conversion of acetone and selectivity of reaction are separately calculated as follows:
Conversion of acetone =(molar flow rate of fed acetone−molar flow rate of discharged acetone)/molar flow rate of fed acetone* 100%
Selectivity of reaction=(molar flow rate of discharged bisphenol A−molar flow rate of fed bisphenol A)/molar flow rate of fed acetone* 100%
According to the process flow diagram as shown in
Both two reactors were fixed bed reactors with same structure and size and charged with same catalyst. Their inside diameters were 200 mm, and the catalyst beds were 400 mm in height.
The rectification column had an inside diameter of 200 mm, and charged with 3 sections of θ net ring packings, wherein a packed section above the feeding site was of 2 m in height and equivalent to 4 theoretical trays, the first packed section below the feeding site was of 1 m in height and equivalent to 2 theoretical trays, and the second packed section below the feeding site was of 2 m in height and equivalent to 4 theoretical trays.
The operation conditions of reactors R1, R2 and rectification column T were as follows:
For R1 and R2, the feed temperature was of 65° C., and the operation pressure was of 6 kg/cm2 (gage pressure). The flow rate of the fed phenol was 3.7 kg/hr, and was totally fed into the first reactor R1. The flow rate of the fed acetone was 0.15 kg/hr to the first reactor R1, and was 0.15 kg/hr to the second reactor R2. The discharged stream from the first reactor was cooled to 65° C. The operation pressure of the rectification column was 100 mmHg (absolute pressure). The flow rate of the side draw was 40 kg/hr. The temperature rise in R2 was controlled within 6° C.
The compositions of each stream of reactors R1 and R2 and rectification column T were shown in Table 1 (based on weight percentage).
In the first reactor R1, the conversion of acetone was 83.5%, and the selectivity of reaction was 92%; and in the second reactor R2, the conversion of acetone was 86%, and the selectivity of reaction was 95.5%.
Operations and conditions were identical to those in Example 1, except that part of the stream 2 out of reactor R2 was not dewatered, but cooled directly and cycled into reactor R2 in a cycled flow rate of 40 kg/hr; and residual part of stream 2 was transferred into the rectification column, wherein no side draw is withdrawn from the rectification column. The compositions of each stream were shown in Table 2 (based on weight percentage).
In the first reactor R1, the conversion of acetone was 83.5%, and the selectivity of reaction was 92%; and in the second reactor R2, the conversion of acetone was 81%, and the selectivity of reaction was 90%;
By comparison, after dewatered, the water content in the reaction stream entering into reactor R2 was reduced from 2.20% to 0.20%, and both the selectivity of reaction and the conversion of acetone were improved significantly.
One fixed bed reactor was used, i.e. acetone, phenol and the cycled side stream from the rectification column were mixed to form a reaction mixture 3a, which directly entered into reactor R2. Except for above difference, all the other operations were identical to those in Example 1.
In the rectification column, no packing was above the feeding site, the first packed section below and adjacent to the feeding site was of 2 m in height and equivalent to 4 theoretical trays; and the second packed section below and from the feeding site was of 1 m in height and equivalent to 2 theoretical trays.
The operation conditions of reactor R2 and rectification column T were as follows:
For reactor R2, the flow rate of the fed phenol was of 3.7 kg/hr, the flow rate of the fed acetone was of 0.3 kg/hr, the feed temperature was of 75° C., and the operation pressure was of 4 kg/cm2 (gage pressure). The operation pressure of rectification column T was 130 mmHg (absolute pressure), and no reflux was provided with said rectification column. The location of side draw was between the two packed sections, and the cycled side flow rate was 24 kg/hr. The reaction temperature rise was controlled within 10° C.
The compositions of each stream of reactor R2 and rectification column T were shown in Table 3 (based on weight percentage).
In reactor R2, the conversion of acetone was 87%, and the selectivity of reaction was 94%.
Comparative Example 2 was substantially identical to Example 2, except that the cycled stream into reactor R2 was not dewatered, but cooled directly and cycled thereinto in a cycled flow rate of 24 kg/hr; no side draw is provided with the rectification column, and the discharged of the reactor was dewatered. The compositions of each stream were shown in Table 4 (based on weight percentage).
In reactor R2, the conversion of acetone was 85%, and the selectivity of reaction was 91%;
By comparison, after dewatered, the water content in the reaction stream entering into reactor R2 was reduced from 2.15% to 0.97%, and both the selectivity of reaction and the conversion of acetone were improved significantly.
Example 3 was substantially identical to Example 2, except that rectification column T was a three-sections packed column, wherein one packed section was above the feeding site, which was of 3 m in height and equivalent to 6 theoretical trays; the first packed section below and adjacent to the feeding site was of 3 m in height and equivalent to 6 theoretical trays; and the second packed section below and adjacent to the feeding site was of 4 m in height and equivalent to 8 theoretical trays.
The operation conditions of reactor R2 and rectification column T were as follows:
For reactor R2, the flow rate of the fed phenol was of 6 kg/hr, the flow rate of the fed acetone was of 0.3 kg/hr, the feed temperature was of 75° C., and the operation pressure was of 5 kg/cm2 (gage pressure). The operation pressure of rectification column T was 760 mmHg (absolute pressure), and the cycled side flow rate was 90 kg/hr. The reaction temperature rise was controlled within 4° C.
The compositions of each stream of reactor R2 and rectification column T were shown in Table 5 (based on weight percentage).
In reactor R2, the conversion of acetone was 87%, and the selectivity of reaction was 96.5%.
Example 4 was substantially identical to Example 2, except that rectification column T was a sieve-plate column with an inside diameter of 200 mm, 25 trays and a tray efficiency of 30%.
The operation conditions of reactor R2 and rectification column T were as follows:
The flow rates of fed phenol and acetone were identical to those in Example 2. The feed temperature was 70° C., and the operation pressure was 5 kg/cm2 (gage pressure). The operation pressure of rectification column T was 60 mmHg (absolute pressure), the feeding site was at the 6th tray, the side draw was at the 13th tray, and the cycled flow rate was 40 kg/hr. The reaction temperature rise was controlled within 6° C.
The compositions of each stream of reactor R2 and rectification column T were shown in Table 6 (based on weight percentage).
The conversion of acetone was 87.5%, and the selectivity of reaction was 95%.
According to the process flow diagram as shown in
The reactors were with the same structure and size as that in Example 1. The flash drum had an inside diameter of 300 mm, and a height of 600 mm. The rectification column had an inside diameter of 200 mm, and charged with two sections of θ net-ring packings, wherein the first packed section from the top of the column was of 2 m in height and equivalent to 4 theoretical trays, and the second packed section was of 2 m in height and equivalent to 4 theoretical trays. The feeding site was above the first packed section.
The operation conditions of reactors R1, R2 and rectification column T were as follows:
For R1 and R2, the feed temperature was of 73° C., and the operation pressure was of 4 kg/cm2 (gage pressure). The flow rate of the fed phenol was 4.5 kg/hr, and was totally added into the first reactor R1. The flow rate of the fed acetone was 0.21 kg/hr to the first reactor R1, and was 0.09 kg/hr to the second reactor R2. The flash drum had an operation pressure of 50 mmHg (absolute pressure), and a cycled flow rate of 40 kg/hr (stream 3). The operation pressure of the rectification column was 50 mmHg (absolute pressure).
The compositions of each stream of reactors R1 and R2 and rectification column T were shown in Table 7 (based on weight percentage).
In the first reactor R1, the conversion of acetone was 83.5%, and the selectivity of reaction was 92%; in the second reactor R2, the conversion of acetone was 88%, and the selectivity of reaction was 96%. This example indicates that a combination of a flash drum and a rectification column is capable of bringing out the substantial same effects as a rectification with side draws.
As to the product fractions primarily containing bisphenol A and phenol obtained in Examples 1 to 5 and Comparative Examples 1 to 2, an adduct crystal of bisphenol A and phenol was obtained by carrying out the crystallization once only. The crystal slurry was filtered, and the filter cake was washed with pure phenol, then the residual phenol was removed to obtain a bisphenol A product, wherein the crystallization temperature was 45° C., and weight of the phenol used for washing the filter cake was 0.5 times as that of the filter cake. The compositions of the obtained products were shown in Table 8.
According to the data shown in Table 8, after once crystallization only, from the product fractions primarily containing bisphenol A and phenol according to the method of the present invention can obtain the bisphenol A products, which meet the specification completely.
| Number | Date | Country | Kind |
|---|---|---|---|
| 03160098.0 | Sep 2003 | CN | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CN04/01097 | 9/24/2004 | WO | 00 | 3/13/2007 |
