CN102040513A - Method for preparing aqueous paste of terephthalic acid through solvent displacement - Google Patents
Method for preparing aqueous paste of terephthalic acid through solvent displacement Download PDFInfo
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- CN102040513A CN102040513A CN2009102016395A CN200910201639A CN102040513A CN 102040513 A CN102040513 A CN 102040513A CN 2009102016395 A CN2009102016395 A CN 2009102016395A CN 200910201639 A CN200910201639 A CN 200910201639A CN 102040513 A CN102040513 A CN 102040513A
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Abstract
The invention relates to a method for preparing an aqueous paste of terephthalic acid through solvent displacement and mainly aims to solve the problems that as the previous technologies utilize the methods of centrifugation, drying and repulping to obtain the aqueous paste of terephthalic acid, the energy consumption is large and the investment cost and operating cost are high. In the method, crude terephthalic acid paste which is obtained through the liquid phase oxidation of p-xylene in acetic acid solvent, is used as original slurry and the method comprises the following steps: a) using p-xylene to displace acetic acid from the original slurry in a first replacement tower to obtain slurry 1 containing p-xylene and terephthalic acid solid particles; and b) using water as displacement liquid to displace p-xylene from the slurry 1 in a second replacement tower to obtain the aqueous paste of terephthalic acid. The problem is better solved by using the technical scheme in the invention and the method can be used in the production process of terephthalic acid.
Description
Technical field
The present invention relates to a kind of solvent exchange and produce the method for terephthalic acid water paste, particularly, produce the method for terephthalic acid water paste with p-Xylol and water two steps displacement about with the resulting crude terephthalic acid slurry of p-Xylol liquid-phase oxidation in acetate solvate.
Background technology
Terephthalic acid usually by p-Xylol in acetic acid solvent, be that catalyzer carries out liquid-phase oxidation and obtains with cobalt, manganese, bromine.4-CBA, PT acid, BA acid and some foreign pigments of removing wherein by the further hydrofining of crude terephthalic acid needs of aforesaid method gained obtain the pure terephthalic acid.Before hydrofining, must remove the acetic acid in the crude terephthalic acid slurry, be mixed with the terephthalic acid water paste.Traditional technology is earlier mother liquor in the crude terephthalic acid to be removed with centrifuging and drying plant combination, and then the water making beating obtains the terephthalic acid water paste, this process not only long flow path, complicated operation but also equipment manufacturing cost height, energy consumption is big, so replace original technology with regard to needing new technology, to satisfy the development of terephthalic acid.
For addressing this problem, several different methods is suggested and realizes the displacement of water to acetic acid in the crude terephthalic acid mother liquor.Document CN1138024A discloses and a kind of terephthalic acid crystals this slurry in acetate has been introduced in the tower at the top that mother liquor is replaced tower, the Guinier-Preston zone of terephthalic acid crystals is formed on the bottom that is deposited in tower by crystal, the water of replacing usefulness joined the inside of tower with the amount of enough formation ascending currents in the bottom of tower and discharge the method for replacing of this crystalline Guinier-Preston zone from tower bottom.By this method, the acetate solvate in the former crude terephthalic acid slurry is replaced by water with high mother liquor displacement degree.United States Patent (USP) 5008450 and CN101255110A have also proposed similar method simultaneously.But the acetic acid water mixed solution of the unavoidable generation a great deal of of meeting in this method of replacing, this can increase the separation costs of acetic acid water mixed liquid greatly.
Document CN1129693A has proposed a kind of compound method of terephthalic acid water paste, it is after the crude terephthalic acid that oxidation obtains is filtered, wash the terephthalic acid crystals that contains acetate with p-Xylol or acetic ester, then itself and water mixing are obtained the terephthalic acid water paste.Though this method can avoid producing the mixing solutions of a large amount of acetic acid and water, this method adopts the intermittent filtration mode of washing, needs repeatedly to wash just can reach certain effect, is unfavorable for large-scale industrial production.
Summary of the invention
Technical problem to be solved by this invention is that the energy consumption that exists in the existing Production of Terephthalic Acid technology is big, cost of investment and the high problem of running cost, provides a kind of new solvent exchange to produce the method for terephthalic acid water paste.This method has that energy consumption is low, investment and the low advantage of running cost.
In order to solve the problems of the technologies described above, the technical solution used in the present invention is as follows: a kind of solvent exchange is produced the method for terephthalic acid water paste, with the resulting crude terephthalic acid slurry of p-Xylol liquid-phase oxidation in acetate solvate is original slurry, may further comprise the steps:
A) at first original slurry displaces wherein acetic acid with p-Xylol in the first displacement tower, obtains containing p-Xylol and terephthalic acid solid particulate slurry 1 simultaneously;
B) slurry 1 uses water as displacement liquid and displace p-Xylol in the second displacement tower, obtains the terephthalic acid water paste.
In the technique scheme, raw material is for being original slurry with the resulting crude terephthalic acid slurry of p-Xylol liquid-phase oxidation in acetate solvate, and the feeding temperature preferable range of original slurry is 130～230 ℃ in the first displacement tower.The mid-p-Xylol feeding temperature preferable range of using instead of the first displacement tower is normal temperature～90 ℃.P-Xylol and crude terephthalic acid slurry volume flow ratio preferable range are 5～0.5: 1 in the first displacement tower, and more preferably scope is 3～1: 1.The second displacement tower mid-feeding temperature preferable range of using water instead is normal temperature～90 ℃; Water and contain p-Xylol and terephthalic acid solid particulate slurry 1 volume flow ratio preferable range is 5～0.4: 1 in the second displacement tower, more preferably scope is 2～0.8: 1.
Adopt two displacement tower series connection among the present invention, displace with p-Xylol in the first displacement tower at first that acetic acid obtains slurry 1 in the crude terephthalic acid slurry, secondly water displaces that p-Xylol obtains the terephthalic acid water paste in the slurry 1 in the second displacement tower.Have good mutual solubility between acetic acid and the p-Xylol owing to closing to fasten in dissolving, water and p-Xylol then do not dissolve mutually.So contain the crude terephthalic acid slurry of a large amount of acetic acid with p-Xylol displacement, can make in the crude terephthalic acid acetic acid content reduce to minimum.And the p-Xylol mixing solutions that contains acetic acid after the displacement can be used as the oxidation raw material and directly enters the oxidation feed system and need not to separate.Water displaces PX in the slurry 1 again, and the CTA filter cake that obtains can be used as refining raw material and directly enters hydrofining workshop section, and the mixed solution of PX that obtains and water need not other separation method owing to immiscible can directly separation the between water and the PX.So isolating method of two steps just is better than the method that direct water displacement crude terephthalic acid slurry is produced the terephthalic acid water paste greatly on energy consumption.
Because hydrofining reaction carries out more than 250 ℃ at high temperature, so the present invention directly sends the resulting crude terephthalic acid slurry of liquid-phase oxidation into displacement tower 1, select 130～230 ℃ of these scope chargings near oxidizing condition, and not by cooling, depressurization step, to avoid the waste of energy; And because the high terephthaldehyde's granulates of temperature settling velocity in the displacement tower is fast, replacement result is good.
Adopt technical scheme crude terephthalic acid mother liquor displacement efficiency height of the present invention, energy consumption little, obtained better technical effect.
Description of drawings
Fig. 1 is a process flow diagram of the present invention.
Among Fig. 1,1 is former stock tank, and 2 is the magma transferpump, 3 is former slurry inlet, and 4 is first CD-ROM drive motor, and 5 is the first displacement tower main shaft, 6 is the first displacement tower sieve plate, and 7 is the first displacement tower, and 8 is the first displacement liquid import, 9 is the first displacement liquid transferpump, and 10 is the first displacement liquid bath, and 11 is the outlet of first displacement liquid, 12 is first mother liquor tank, 13 is first slurry outlet, and 14 is slurry 1 storage tank, and 15 is slurry 1 transferpump, 16 is slurry 1 import, 17 is second CD-ROM drive motor, and 18 is the second displacement tower main shaft, and 19 is the second displacement tower sieve plate, 20 is the second displacement tower, 21 is the second displacement liquid import, and 22 is the second displacement liquid transferpump, and 23 is the second displacement liquid bath, 24 is the outlet of second displacement liquid, 25 is second mother liquor tank, and 26 are the outlet of terephthalic acid water paste, and 27 is terephthalic acid water paste groove.
The present invention is further elaborated below by embodiment.
Embodiment
[embodiment 1]
By shown in Figure 1, be that raw material (wherein acetic acid 92%, water 7.7% and small amounts catalyzer) experimentizes with the crude terephthalic acid slurry of certain terephthalic acid factory.Used first, second displacement tower main body is made by the titanium material, and the outside is surrounded by lagging material.Two tower structures are measure-alike, divide equally three sections compositions, 80 millimeters of the high 150 millimeters rounded section diameters in top settling section zone, and 60 millimeters of high 900 mm dias in displacement section zone, the solid windrow section zone of tower body bottom is the back taper design, 60 millimeters of cone height; CD-ROM drive motor is installed in the tower top, is connected with main shaft down, be connected with 10 sieve plates 9 that are distributed in the displacement section zone on the axle, distance between plates is 90 millimeters.Import and export at slurry simultaneously, and the displacement liquid import and export is separately installed with under meter.In addition, on tower, also be provided with several portholes.
At first, driving p-Xylol pump 9 sends into 85 ℃ of p-Xylol in the first displacement tower 7 from the first displacement liquid bath 10.Treat that p-Xylol is full of the whole first displacement tower, and when first displacement liquid exported 11 overflow to the first mother liquor tanks 12, control p-Xylol feed rate was 40 ml/min.Starting first CD-ROM drive motor, 4 control sieve plate vibration frequencies simultaneously is 60 times/minute.Then, drive feedstock pump 2 with 140 ℃ in the head tank 1 slightly benzene is sent in the first displacement tower 7 from import 3, dominant discharge is 40 ml/min, and promptly p-Xylol and crude terephthalic acid slurry volume flow ratio are 1: 1.During from the full conical section of porthole observing tower 7 bottom solid stockpiles, begin from discharge port 13 discharges, the control discharge rates guarantees that the windrow section is stable.
After the first displacement tower moves 1 hour, drive the second displacement liquid transferpump 22 90 ℃ of displacement waters in the second displacement liquid bath 23 are sent in the second displacement tower from import 21.Treat that water is full of the second displacement tower, and when exporting 24 overflows to groove 25 from second displacement liquid, control replacing water flow is 40 ml/min.Starting second CD-ROM drive motor, 17 control sieve plate vibration frequencies simultaneously is 60 times/minute.Then, driving pump 15 is sent into slurry 1 in the second displacement tower 20 from groove 14, and control slurry 1 flow is 40 ml/min, and promptly the volume flow ratio of water and slurry 1 is 1: 1.During from the full conical section of porthole observing tower 20 bottom solid stockpiles, begin from discharge port 26 discharges, the control discharge rates guarantees that the windrow section is stable.
From discharge port 13 and 26 samplings, the cooling post analysis is acetic acid and p-Xylol content wherein after system is stablized 3 hours.Wherein acetic acid content is 99.72% in 0.21%, the first displacement tower rate of displacement in the slurry 1.Slurry 2 is acetic acid content in the terephthalic acid water paste＜0.01%, and p-Xylol content is 0.13%.
[embodiment 2～6]
Repeat the step of example 1, different is to change p-Xylol and crude terephthalic acid feeding temperature in the first displacement tower, and the displacement water temp the results are shown in Table 1 in the second displacement tower
Table 1
[embodiment 7～10]
The step of repetition example 1, different is to change p-Xylol and crude terephthalic acid flow in the first displacement tower, and the flow of interior replacing water of the second displacement tower and slurry 1, the results are shown in Table 2.
Table 2
[comparative example 1]
Adopt charging testing sequence and the feed rate temperature of embodiment 1, just only use the first displacement tower among Fig. 1, and change displacement liquid wherein into water, promptly obtain the terephthalic acid water paste with a direct water displacement of displacement tower, test-results shows that the acetic acid rate of displacement is 99.87%.Sneak into big water gaging in the effusive mother liquor but the first displacement tower displacement liquid exports, this part water must separate to walk, and acetic acid just can be reused.In PTA produces acetic acid and water separate very difficultly, a stage number is surpassed 80 acetic acid dehydrating tower, reflux ratio is greater than 4 and distillates that acetic acid content could be up to standard in the water, so energy consumption is very big.
So adopt technical scheme of the present invention obviously to cut down the consumption of energy, have obvious technical superiority.
Claims (8)
1. a solvent exchange is produced the method for terephthalic acid water paste, is original slurry with the resulting crude terephthalic acid slurry of p-Xylol liquid-phase oxidation in acetate solvate, may further comprise the steps:
A) at first original slurry displaces wherein acetic acid with p-Xylol in the first displacement tower, obtains containing p-Xylol and terephthalic acid solid particulate slurry 1 simultaneously;
B) slurry 1 uses water as displacement liquid and displace p-Xylol in the second displacement tower, obtains the terephthalic acid water paste.
2. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 1, it is characterized in that the feeding temperature of original slurry in the first displacement tower is 130～230 ℃.
3. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 1, it is characterized in that in the first displacement tower feeding temperature of p-Xylol is normal temperature～90 ℃.
4. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 1, it is characterized in that p-Xylol and crude terephthalic acid slurry volume flow ratio are 5～0.5: 1 in the first displacement tower.
5. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 4, it is characterized in that p-Xylol and crude terephthalic acid slurry volume flow ratio are 3～1: 1 in the first displacement tower.
6. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 1, it is characterized in that in the second displacement tower feeding temperature of water is normal temperature～90 ℃.
7. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 1, it is characterized in that water and slurry 1 volume flow ratio are 5～0.4: 1 in the second displacement tower.
8. produce the method for terephthalic acid water paste according to the described solvent exchange of claim 7, it is characterized in that water and slurry 1 volume flow ratio are 2～0.8: 1 in the second displacement tower.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103121937A (en) * | 2011-11-18 | 2013-05-29 | 中国石油化工股份有限公司 | Method for removing acetic acid in crude isophthalic acid filter cakes |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3624145A (en) * | 1969-02-17 | 1971-11-30 | Du Pont | Purification of terephthalic acid by liquid-liquid extraction |
| CN1129693A (en) * | 1994-11-15 | 1996-08-28 | 三菱化学株式会社 | Preparation of aqueous paste of terephthalic acid |
| CN1510023A (en) * | 2002-12-26 | 2004-07-07 | 中国石化集团天津石油化工公司 | Process for primary refining coarse p-phthalic acid by solvent washing process |
| CN1819985A (en) * | 2003-10-02 | 2006-08-16 | 三菱瓦斯化学株式会社 | Method for producing high purity terephthalic acid |
| CN101255110A (en) * | 2007-02-28 | 2008-09-03 | 三菱瓦斯化学株式会社 | Method for preparing terephthalic acid |
-
2009
- 2009-10-13 CN CN2009102016395A patent/CN102040513A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3624145A (en) * | 1969-02-17 | 1971-11-30 | Du Pont | Purification of terephthalic acid by liquid-liquid extraction |
| CN1129693A (en) * | 1994-11-15 | 1996-08-28 | 三菱化学株式会社 | Preparation of aqueous paste of terephthalic acid |
| CN1510023A (en) * | 2002-12-26 | 2004-07-07 | 中国石化集团天津石油化工公司 | Process for primary refining coarse p-phthalic acid by solvent washing process |
| CN1819985A (en) * | 2003-10-02 | 2006-08-16 | 三菱瓦斯化学株式会社 | Method for producing high purity terephthalic acid |
| CN101255110A (en) * | 2007-02-28 | 2008-09-03 | 三菱瓦斯化学株式会社 | Method for preparing terephthalic acid |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103121937A (en) * | 2011-11-18 | 2013-05-29 | 中国石油化工股份有限公司 | Method for removing acetic acid in crude isophthalic acid filter cakes |
| CN103121937B (en) * | 2011-11-18 | 2015-04-08 | 中国石油化工股份有限公司 | Method for removing acetic acid in crude isophthalic acid filter cakes |
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Application publication date: 20110504 |