CN1162392C - High-pressure waste TA converting process of preparing DMT - Google Patents
High-pressure waste TA converting process of preparing DMT Download PDFInfo
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- CN1162392C CN1162392C CNB021128170A CN02112817A CN1162392C CN 1162392 C CN1162392 C CN 1162392C CN B021128170 A CNB021128170 A CN B021128170A CN 02112817 A CN02112817 A CN 02112817A CN 1162392 C CN1162392 C CN 1162392C
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- terephthalic acid
- esterification
- dmt
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- methyl alcohol
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Abstract
The present invention relates to a converting and utilizing process for chemical waste materials, particularly to a process for converting a waste low-purity terephthalic acid (TA) material into high-purity dimethyl terephthalateat (DMT) under the high-pressure condition. The waste TA material dried and processed is directly loaded in a kettle to be esterified with methanol under the high-pressure condition; the DMT can be prepared by distilling and purifying an obtained esterified substance twice, and methyl ester of other organic acids can be recovered. The converting process selects suitable reaction conditions without adding a catalyst, a preprocessing step for the waste material is comparatively simple, and the intermediate esterified substance which does not need to be washed in water can be directly distilled and purified. The present invention has the characteristics of short flow, high heat efficiency, little pollution, high recovery rate, high product purity, etc.
Description
Relate to the field:
The present invention relates to a kind of chemical spent material trans-utilization technology, the terephthalic acid (TA) that is in particular low-purity transforms the reparation technology of reuse to dimethyl terephthalate (DMT) (DMT).
Background technology:
Pure terephthalic acid (PTA) is a kind of important chemical product, is one of main raw material of polyester (PET) production.Usually produce in the industrial PTA production process with a large amount of terephthaldehyde's acid waste products (useless TA).Along with world's PET production capacity constantly increases, the PTA demand rises day by day, and correspondingly, useless TA amount increases thereupon.This waste material foreign matter content is about 10%, can not directly apply to PET production, thereby cheap, and the experience of free material was once arranged.For this industrial waste, domesticly existing utilize technology to mainly contain: 1. terephthaldehyde's acid residue production dimethyl terephthalate (DMT) (Jiangsu chemical industry 97. " 6 ") is catalyzer with sulfuric acid with after methanol esterification becomes ester, again through separating, washing, distilling and make DMT.2. dimethyl terephthalate (DMT) novel process research (Jiangsu chemical industry 00. " 3 ") is done the catalyzer esterification with titanium sulfate, obtains DMT again through separating, wash, distilling.3. the PTA oxidation residua prepare softening agent (Guangdong chemical industry (97 " 12 "), waste material be through washing, molten, the decolouring of alkali, acidifying, water collection, acidylate, esterification, washing, distillation, product DOP/DOTP.In addition, the utilization of useless TA material also has the alkali-soluble acid analysis of employing or directly washes and produce crude terephthalic acid; Become monooctyl ester or butyl ester as softening agent with octanol or butanols catalytic esterification; Be used for gunpowder filler etc.The dissolution with solvents method of U.S. Amoco exploitation is that useless TA is made PTA through dissolving, decolouring, filtration, washing.Described these methods still can not effectively solve the pollution and the waste material of conversion process to be dissolved and problems such as the rate of recovery is low, and solves the target that this type of problem is industrial effort always.
Summary of the invention:
The present invention is intended to solve the above-mentioned defective of prior art and provides a kind of and make full use of component in the useless TA material, improves and transform the rate of recovery, reduce a kind of useless terephthalic acid high pressure converted that transforms secondary pollution, increases transformation benefit and produce dimethyl terephthalate (DMT) technology.
Purpose of the present invention can realize by following technical solution:
A kind of useless terephthalic acid high pressure converted is produced dimethyl terephthalate (DMT) technology, comprise esterification, dealcoholysis, distillation, fractionation purification process, wherein said in esterification step, do not add catalyzer, useless terephthalic acid material directly joins reactor and methyl alcohol carries out esterification, and esterification transforms from being pressurized under the 2.5-3.5Mpa gauge pressure condition by heating up.
Purpose of the present invention can also be come further accomplished by following technology solution:
Aforesaid useless terephthalic acid high pressure converted is produced dimethyl terephthalate (DMT) technology, include oven dry, esterification, dealcoholysis, distillation, the fractionation purification process, in the high pressure esterification step, need not to add in addition catalyzer, useless TA material after the oven dry processing is directly added reactor and methyl alcohol carry out esterification, reaction pressure is 2.5-3.5MPa (gauge pressure), temperature is 180-230 ℃, the mole add-on of its methyl alcohol should be in excess in the molar weight of the carboxyl in the useless TA material, at first transforms and makes thick ester, after esterification process is finished, keep the condition of high temperature, pressure is progressively reduced to normal pressure, remove and collect excessive methyl alcohol, change the fractionation purification process then over to and handle.In fractionation purification processes operation, at first the thick ester under the hot condition is decompressed to 50mmHg (absolute pressure) step by step, collect the fraction below 180 ℃, this fraction is the low ester that boils, the fraction of collecting 180-200 ℃/50mmHg scope then is thick DMT.After the secondary fractionation was handled, the fraction of collecting 184-188 ℃/50mmHg promptly got DMT to thick DMT again.
After the invention has the advantages that useless TA adopts the high pressure esterification treatment, esterification yield can reach 95%, and conversion product DMT purity is greater than 99%.P-methylbenzoic acid among the useless TA etc. mixes acid and together be converted to corresponding methyl esters in esterification process, can be used as by product during distillation and is reclaimed.What this technology was taked is closed conversion, and externally the material of discharging is few, and rate of recovery height can realize transforming minimize contamination.Useless TA material is purified directly into still esterification, thick ester straight-forward fractional distillation, and the setting that two " directly " handles can simplify conversion process greatly, improves thermo-efficiency, increases the rate of recovery, and can exempt the pollution problem that water washing process brings.
Description of drawings:
Fig. 1 is a technological process sketch of the present invention.
Embodiment:
As shown in Figure 1, oven dry, esterification, dealcoholysis, distillation, fractionation purification process have been the present invention includes.In the high pressure esterification step, need not to add in addition catalyzer, useless TA drying is handled the back and is carried out esterification directly into still and methyl alcohol, reaction pressure is 2.5-3.5MPa (gauge pressure), temperature is 180-230 ℃, the mole add-on of its methyl alcohol should be in excess in the molar weight of the carboxyl in the useless TA material, and the optimum molar add-on of methyl alcohol is: methyl alcohol: the carboxyl=1.5-3 in the useless TA material: 1.With this understanding, useless TA at first changes into thick ester.After esterification process finishes, keep the condition of high temperature, progressively reduce pressure, discharge esterification water, reclaim excessive methanol, change underpressure distillation then over to and handle to normal pressure.In the underpressure distillation operation, reduce pressure gradually to 50mmHg (absolute pressure), hang down respectively the ester that boils (below 180 ℃/50mmHg), thick DMT (180-200 ℃/50mmHg) with the separated and collected of different foreign material, obtain respectively: reclaim methyl alcohol, the low ester that boils, thick DMT and residue.To reclaim methyl alcohol, the low ester that boils, thick DMT fractionation respectively more at last, obtain: reuse methyl alcohol, by product and product DMT.
Embodiment one:
Useless TA material in the autoclave of packing into, adds the methyl alcohol of 3 times of weight, the heat temperature raising esterification after 160 ℃ of oven dry.Pressure-controlling is controlled at 230 ℃ in 2.5MPa (gauge pressure), temperature, and esterification time is 15 hours.After esterification process is finished, progressively reduce pressure, discharge esterification water, reclaim excessive methanol to normal pressure.Progressively be decompressed to 50mmHg (absolute pressure) again, the low-boiling-point substance of fraction below 180 ℃ is reclaimed in distillation, and regathering 180-200 ℃ afterwards is thick DMT with interior fraction, obtains respectively: reclaim methyl alcohol, low-boiling-point substance, thick DMT and residue.Reclaim methyl alcohol, low-boiling-point substance, thick DMT fractionation respectively again, obtain: reuse methyl alcohol, by product and product DMT.
Embodiment two:
Useless TA material in the autoclave of packing into, adds the methyl alcohol of 3 times of weight and the thick DMT of about 8% weight, the heat temperature raising esterification after 170 ℃ of oven dry.Pressure-controlling is controlled at 215 ℃ in 3.5MPa (gauge pressure), temperature, and esterification time is 16 hours.After esterification process is finished, progressively reduce pressure, discharge esterification water, reclaim excessive methanol to normal pressure.Progressively be decompressed to 50mmHg (absolute pressure) again, the low-boiling-point substance of fraction below 180 ℃ is reclaimed in distillation, and regathering 180-200 ℃ afterwards is thick DMT with interior fraction, obtains respectively: reclaim methyl alcohol, low-boiling-point substance, thick DMT and residue.Reclaim methyl alcohol, low-boiling-point substance, thick DMT fractionation respectively again, obtain: reuse methyl alcohol, by product and product DMT.
Embodiment three:
Useless TA material in the autoclave of packing into, adds the methyl alcohol of 3 times of weight and the thick DMT of about 10% weight, the heat temperature raising esterification after 180 ℃ of oven dry.Pressure-controlling is controlled at 230 ℃ in 3MPa (gauge pressure), temperature, and esterification time is 15 hours.After esterification process is finished, progressively reduce pressure, discharge esterification water, reclaim excessive methanol to normal pressure.Progressively be decompressed to 50mmHg (absolute pressure) again, the low-boiling-point substance of fraction below 180 ℃ is reclaimed in distillation, and regathering 180-200 ℃ afterwards is thick DMT with interior fraction, obtains respectively: reclaim methyl alcohol, low-boiling-point substance, thick DMT and residue.Reclaim methyl alcohol, low-boiling-point substance, thick DMT fractionation respectively again, obtain: reuse methyl alcohol, by product and product DMT.Produce DMT and intermittently finish in two steps in 0.5 liter of autoclave, the useless TA of per 100 grams expects, needs methyl alcohol 300 grams, can mix thick ester 109 grams, gets thick DMT 98 grams after distillation, and esterification yield is greater than 95%.Thick DMT again fractionation get final product the DMT product.These product check and analysis result is:
Outward appearance---liquid is colourless transparent liquid down, and normal temperature is white crystals
Purity---liquid chromatography 99.1% gas-chromatography 99.8%
Fusing point---140.5 ℃
Colourity---25APHA
Acid number≤4.8mgKOH/g
The foregoing description is non-limiting example, and all excessive by weight proportion adding of methyl alcohol among each embodiment also can recently be selected methanol usage according to the optimum molar of the carboxyl in aforementioned methyl alcohol and the useless TA material when specifically implementing.
Claims (5)
1. a useless terephthalic acid high pressure converted is produced dimethyl terephthalate (DMT) technology, comprise esterification, dealcoholysis, distillation, fractionation purification process, it is characterized in that: in esterification step, do not add catalyzer, useless terephthalic acid material directly joins reactor and methyl alcohol carries out esterification, and esterification transforms from being pressurized under the 2.5-3.5Mpa gauge pressure condition by heating up.
2. useless terephthalic acid high pressure converted according to claim 1 is produced dimethyl terephthalate (DMT) technology, it is characterized in that: useless terephthalic acid material is handled through 160-180 ℃ of oven dry, directly add then in the reactor and carry out esterification with the interior methyl alcohol of still, the mole add-on of its methyl alcohol should be in excess in the molar weight of the carboxyl in the useless terephthalic acid material, esterification reaction pressure is the 2.5-3.5MPa gauge pressure, temperature is 180-230 ℃, at first transform and make thick ester, progressively reduce pressure after esterification process is finished and reduce to normal pressure, discharge is also reclaimed excessive methyl alcohol, changes fractionation purification processes operation then over to.
3. useless terephthalic acid high pressure converted according to claim 2 is produced dimethyl terephthalate (DMT) technology, it is characterized in that the mole add-on of described methyl alcohol is: methyl alcohol: the carboxyl=1.5-3 in the useless terephthalic acid material: 1.
4. useless terephthalic acid high pressure converted according to claim 1 is produced dimethyl terephthalate (DMT) technology, it is characterized in that: in the fractionation purification process, at first the thick ester under the hot condition is decompressed to the 50mmHg absolute pressure gradually, collect fraction below 180 ℃ and be the low ester that boils, and then the fraction of collecting 180-200 ℃/50mmHg scope is the crude terephthalic acid dimethyl ester, the crude terephthalic acid dimethyl ester is handled through the secondary fractionation again, and the fraction of collecting 184-188 ℃/50mmHg promptly obtains purity greater than high purity terephthalic acid's dimethyl ester of 99%.
5. useless terephthalic acid high pressure converted according to claim 1 is produced dimethyl terephthalate (DMT) technology, it is characterized in that: before carrying out the high pressure esterification, the crude terephthalic acid dimethyl ester that adds useless terephthalic acid material 8-10% weight is participated in esterification together.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CNB021128170A CN1162392C (en) | 2002-03-28 | 2002-03-28 | High-pressure waste TA converting process of preparing DMT |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB021128170A CN1162392C (en) | 2002-03-28 | 2002-03-28 | High-pressure waste TA converting process of preparing DMT |
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| Publication Number | Publication Date |
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| CN1374289A CN1374289A (en) | 2002-10-16 |
| CN1162392C true CN1162392C (en) | 2004-08-18 |
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| CNB021128170A Expired - Lifetime CN1162392C (en) | 2002-03-28 | 2002-03-28 | High-pressure waste TA converting process of preparing DMT |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102219689A (en) * | 2011-04-26 | 2011-10-19 | 万载县中昊新能源开发有限公司 | Method for producing dimethyl terephthalate (DMT) |
| CN105294444A (en) * | 2014-06-06 | 2016-02-03 | 中国石油化工股份有限公司 | Method for one-step synthesis of phenyl salicylate from carbon dioxide and phenol |
| CN106187766B (en) * | 2015-05-06 | 2019-04-23 | 中国科学院大连化学物理研究所 | A kind of processing method of o-Xylene Oxidation in Liquid Phase residue |
| CN105017022A (en) * | 2015-07-20 | 2015-11-04 | 浙江大学 | Method for methyl esterification recovery and recycle of PTA oxidation residue |
| CN112876357A (en) * | 2021-01-20 | 2021-06-01 | 江苏福昌环保科技集团有限公司 | Production process for producing plasticizer from PTA oxidation residues |
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- 2002-03-28 CN CNB021128170A patent/CN1162392C/en not_active Expired - Lifetime
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Effective date of registration: 20160205 Address after: 211900 Yizheng Changjiang Road, Jiangsu, China, No. 1, No. Patentee after: CHINA SINOPEC YIZHENG CHEMICAL FIBER CO., LTD. Address before: 211900 Jiangsu city of Yizheng province Xupu Patentee before: Yizheng Chemical Fiber Co., Ltd., China Petrochemical Group Corp. |
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