TH92803A - The process for separation of dialkyls Carbonates are industrialized. - Google Patents

Abstract

One purpose of this invention is to provide a specific apparatus and process for the use of a single distillation column of a low-boiling point reactive mixture of dialkyl carbonate and aliphatic monohydric alcohol produced by reactive distillation using cyclic carbonate and aliphatic monohydric alcohol as feedstocks; continuous feeding of the feedstocks into a continuous multi-stage distillation column containing a homogeneous catalyst; and simultaneous reaction and distillation within the column to separate the low-boiling point reactive mixture into a top component BT, predominantly composed of aliphatic monohydric alcohol, and a bottom component BB, predominantly composed of dialkyl carbonate. It is a key component of the aforementioned substances and can be stably separated for extended periods industrially. Furthermore, another objective, achieved with specific, inexpensive equipment and processes, is the ability to stably separate dialkyl carbonate by distillation in quantities of, for example, no less than 2 tons/hour for extended periods (i.e., no less than 1000 hours, ideally no less than 3000 hours, and even better, no less than 5000 hours). It has been revealed that from the by-products of dialkyl carbonate and diol produced through reactive distillation from cyclic carbonate and aliphatic monohydric alcohols, high-purity dimethyl carbonate with a purity of no less than 97% by weight, ideally no less than 99% by weight, and even better, no less than 99.9% by weight, can be made... Achieved at an industrial scale of not less than 2 tons/hour, with a goodness of not less than 3 tons/hour, with a goodness of not less than 4 tons/hour, with a high and stable yield for a period of not less than 1000 hours, with a goodness of not less than 3000 hours, with a goodness of not less than 5000 hours. One purpose of this invention is to provide a specific apparatus and process for the use of a single distillation column of a large low-boiling point reactive mixture of dialkyl carbonate and aliphatic monohydric alcohol produced through reactive distillation using cyclic carbonate and aliphatic monohydric alcohol as feedstocks, continuous feeding of feedstocks into a continuous multi-stage distillation column containing a homogeneous catalyst, and simultaneous reaction and distillation within the column, in order to separate the low-boiling point reactive mixture into the top component of the BT distillation column containing aliphatic monohydric alcohol. The main component of the aforementioned substance, and the BB distillation column's end component, which primarily consists of dialkyl carbonate, can be stably separated for extended periods industrially. Furthermore, another objective, accomplished with specific, inexpensive equipment and processes, is to stably separate dialkyl carbonate by distillation in quantities of, for example, not less than 2 tons/hour for extended periods (i.e., not less than 1000 hours, ideally not less than 3000 hours, and even better not less than 5000 hours). It has been revealed that from the by-products of dialkyl carbonate and diol produced through reactive distillation systems from cyclic carbonate and aliphatic monohydric alcohols, high-purity dimethyl carbonate with a purity of not less than 97% by weight, ideally not less than 99% by weight, and even better not less than 99.9% by weight, can be made... Achieved at an industrial level of not less than 2 tons/hour, ideally not less than 3 tons/hour, and even better not less than 4 tons/hour, with high and stable output over a period of not less than 1000 hours, ideally not less than 3000 hours, and even better not less than 5000 hours.

Claims (27)

------08/06/2561------(OCR) Page 1 of 4 pages. Claims 1. An industrial process for the separation of dialkyl carbonates consisting of the following steps: continuous feeding of reactants into a series of multistage distillation column A containing a homogeneous catalyst using cyclic carbonate and aliphatic monohydric alcohol as reactants; active distillation in the said distillation column A; continuous extraction of a high-boiling point reaction mixture Ab containing dialol produced from the bottom of the said distillation column A in liquid form; continuous extraction of a low-boiling point reaction mixture At containing the dialkyl carbonate produced and aliphatic monohydric alcohol from the top of the said distillation column A in gaseous form; continuous feeding of the said low-boiling point reaction mixture At into a series of multistage distillation column B; and separation by distillation into the top distillation component BT containing aliphatic alcohol. Monohydric alcohol is the dominant component of the substance, and the terminal component of the distillation column Bb, with diallyl carbonate as the dominant component, is improved by a series of successive multistage distillation columns. This substance B consists of a distillation column with an extraction section of length L (cm) and inner diameter D (cm) and an inner step containing the number of steps T1, and a bulk section of length L2 (cm) and inner diameter D2 (cm) and an inner step containing the number of steps T2, where L? D? T,, L2, A2 and T2 are provided by the following formulas (1) to (8): 500 (symbol) L1 (symbol) 3000 (1) 100 (symbol) D1 (symbol) 1000 (2) 2 (symbol) L1/D1 (symbol) 30 (3) 10 (symbol) n1 (symbol) 40 (4) 700 (symbol) L2 (symbol) 5000 (5) 50 (symbol) D2 (symbol) 800 (6) 10 (symbol) L2/D2 (symbol) 50 (7), and 35 (symbol) n2 (symbol) 100 (8) Page 2 of 4 pages 2. The process under claim 1 where the amount of dialkyl carbonate separated is not less than 2 ton/hr. 3. The process under claim 1 or 2 where L? A,, L,/D? T,, L2, Dj, L2/D2 and T2 of the continuous multistage distillation column B as described above conforms to 800< L, <2500, 120 < D, <800,5 < L,/D, < 20, 13 < T, < 25, 1500 < L2 < 3500, 70 < A2 < 600, 15 < L2/D2 < 30, 40 < T2 < 70, L, 4. The process according to any of the claims 1 through 3 where the inner phase of each section of the extraction and bulk phase of the continuous multistage distillation column B is a tray and/or container. 5. The process according to claim 4 where the inner phase of the extraction and bulk phase of the distillation column. Several consecutive steps B. The said tray is a sieve tray. 7. The process according to claim 5, where the said tray is a sieve tray. 8. The process according to claim 6, where the said sieve tray has 150 to 1200 holes/m² in the sieve section of the said object, and the cross-sectional area per hole is in the range from 0.5 to 5 cm². 9. The process according to claim 6 to 7, where the said sieve tray has 200 to 1100 holes/m² in its sieve section, and the cross-sectional area per hole is in the range from 0.7 to 4 cm². 10. The process according to any one of claims 6 to 8, where the said sieve tray has 250 to 1000 holes/m² in the sieve section of the said object, and the cross-sectional area per hole is in the range from 0.9 to 3 cm². 11. The process according to any one of claims 1 to 9. 10. A continuous multistage distillation column B has a distillation outlet temperature ranging from 150 to 250 degrees Celsius. 11. Any one of the claims 1 to 10, where the continuous multistage distillation column B has a reflux ratio ranging from 0.5 to 5. 12. Any one of the claims 1 to 1, where the concentration of dialkyl carbonate in the end-stage distillation component B is not less than 97% by mass based on 100% by mass of the end-stage component. 13. Any one of the claims 1 to 12, where the concentration of dialkyl carbonate in the end-stage distillation component BB... Such a process under claims 1 to 13 where the concentration of dialkyl carbonate in the aforementioned Bb end-concentrate is not less than 99.9% by mass on the basis of 100% by mass of the aforementioned end-concentrate. Page 3 of 4, page 14. 15. 16. 17. 18. 19 ... It contains methanol and/or ethanol, and the separated dialkyl carbonate contains dimethyl carbonate and/or diethyl carbonate. 17. Any of the processes under claims 1 through 16 that produce dialkyl carbonate containing a halogen content of no more than 0.1 parts per million. 18. Any of the processes under claims 1 through 16 that produce dialkyl carbonate containing a halogen content of no more than 1 part per billion. 19. A process under claim 17 or 18 that produces high-purity dialkyl carbonate containing aliphatic monohydric alcohol of no more than 0.1% by mass and containing a halogen content of no more than 1 part per billion. 20. A continuous multistage distillation column that is a continuous multistage distillation column B for the conduction of A low-boiling point mixture At, containing produced dialkyl carbonate and aliphatic monohydric alcohol, is separated by distillation into a top distillation column Bt, predominantly composed of aliphatic monohydric alcohol, and a bottom distillation column Bb, also predominantly composed of dialkyl carbonate. The low-boiling point mixture At is obtained by using cyclic carbonate and aliphatic monohydric alcohol as starting materials, continuous infusion of these starting materials into a multi-stage distillation column A containing a homogeneous catalyst, active distillation in column A, continuous extraction of the high-boiling point mixture Ab, containing the produced dialol from the bottom of the distillation column in liquid form, and continuous extraction of the low-boiling point mixture At from the top. The distillation column in the image is a gas, where the multistage continuous distillation column B consists of: 4 pages of 4 faces, an extraction section with length L (cm) and an inner diameter D (cm), and an inner layer containing the number of layers T1, and a bulk section with length N (cm) and an inner diameter W2 (cm), and an inner layer containing the number of layers T2, where L? D? T1, L2, D2 and T2 are subject to the following formulas (1) to (8): 500 < Nu < 3000(1), 100 < V, < 1000(2), 2< Nu/V1<30(3), 10< T1<40(4), 700 < Nu < 5000(5), 50 < 02 < 800(6), 10< Nu/V2<50(y), and 35 < T2 < 100(8). 21. A continuous multistage distillation column according to claim 20 where Nu, V, Nu/V, T,, L2, D2, Nu/V2 and T2 are subject to 800<Nu<2500, 120<V,<800,5 < L1/V,<20, 13<T,<25, 1500 < Nu < 3500, 70 < V2 < 600, 15 < Nu/V2 < 30, 40 < T2 < 70, Nu < Nu and V2 < /V, 22. A continuous multi-stage distillation column pursuant to claim clause 20 or 21, where the inner layer of each section 23. A continuous multistage distillation column pursuant to claim 22, where the innermost layer of each section of the extraction and bulk is a tray. 24. A continuous multistage distillation column pursuant to claim 23, where such trays are sieve trays. 25. A continuous multistage distillation column pursuant to claim 24, where such sieve trays have 150 to 1200 holes/m² in its sieve section, and the cross-sectional area per hole is in the range of 0.5 to 5 cm². 26. A continuous multistage distillation column pursuant to claim 24 or 25, where such sieve trays have 200 to 1100 holes/m² in its sieve section, and the cross-sectional area per hole is in the range of 0.7 to 4 cm². 27. A continuous multistage distillation column pursuant to any one of claims 24 to 26. The sieve tray has 250 to 1000 holes/m² in its sieve section, and the cross-sectional area per hole ranges from 0.9 to 3 cm². 1. The industrial process for the separation of dialkyl carbonates consists of the following steps: continuous feeding of reactants into a multistage distillation column A containing a homogeneous catalyst using cyclic carbonate and aliphatic monohydric alcohol as reactants; reactive distillation in column A; continuous extraction of a high-boiling point mixture AB containing the dialol produced from the bottom of column A in liquid form; continuous extraction of a low-boiling point mixture AT containing the dialkyl carbonate produced from the top of column A in gaseous form; continuous feeding of the low-boiling point mixture AT into a multistage distillation column B; and separation by distillation into a top component BT, with aliphatic monohydric alcohol as the main component, and a bottom component BB, containing dialkyl carbonate. Carbonate is the main component of such a structure, where the improvement consists of: a series of consecutive multistage distillation columns B such a structure consists of an extraction section with length L1 (cm) and inner diameter D1 (cm) and an inner layer containing the number of steps n1 in it, and a bulk section with length L2 (cm) and inner diameter D2 (cm) and an inner layer containing the number of steps n2 in it, where L1, D1, n1, L2, D2 and n2 satisfy the following formulas (1) to (8): 500<_L1<_3000 (1) 100<_D1<_1000 (2) 2<_L1/D1<_30 (3) 10<_n1<_40 (4) 100<_L2<_5000 (5) 50<_D2<_800 (6) 10<_L2/D2<_50 (7), and 35<_n2<_100 (8) 2. The process stipulated in claim 1, where the production volume of dialkyl carbonate is not less than 2 tons/hour. 3. The process according to claim 1 or 2 where L1, D1, L1/D1, n1, L2, D2, L2/D2 and n2 satisfy 800<_L1<_2500, 120<_D1<_800, 5<_L1/D1<_20, 13<_n1<_25, 1500<_L2<_3500, 70<_D2<_600, 15<_L2/D2<_30, 40<_n2<_70, L1<_L2 and D2<_/D1. 4. Any of the processes described in Claims 1 through 3 whereby the inner layers of each section of the extraction and bulk sections of a successive multistage distillation column B are trays and/or containers. 5. The process under claim 4, where the inner layer of the extraction section and the bulk section of the distillation column, are successive multi-stage steps, as described in B, are trays. 6. The process under claim 5, whereby the tray is a sieve tray. 7. The process pursuant to claim paragraph 6, whereby the sieve tray contains 150 to 1200 holes/m² in the sieve portion and the cross-sectional area per hole is in the range of 0.5 to 5 cm². 8. Processes according to claims 6 or 7, where the sieve has 200 to 1100 holes/m² in its sieve section, and the cross-sectional area per hole is in the range of 0.7 to 4 cm². 9. Any process under claims 6 through 8 where the sieve has 250 to 1000 holes/m² in the sieve portion and the cross-sectional area per hole is in the range of 0.9 to 3 cm². 10. Any of the processes described in Claims 1 through 9, where a continuous multi-stage distillation column B has a tip temperature ranging from 150 to 250 °C. 11. Any of the processes described in Claims 1 through 10, where a continuous multi-stage distillation column B has a reflux distillation ratio ranging from 0.5 to 5. 12. Any of the processes under Claims 1 through 11 where the concentration of dialkyl carbonate in the BB end-of-the-flow component is not less than 97% by weight on the basis of 100% by weight of the said end-of-the-flow component. 13. Any of the processes under Claims 1 through 12 where the concentration of dialkyl carbonate in the BB end-of-the-flow component is not less than 99% by weight on the basis of 100% by weight of the said end-of-the-flow component. 14. Any of the processes under Claims 1 through 13 where the concentration of dialkyl carbonate in the BB end-of-the-flow component is not less than 99.9% by weight on the basis of 100% by weight of the said end-of-the-flow component. 15. Any of the processes described in Claims 1 through 14, whereby the top components of the BT distillation column are recycled as feedstocks for the production of dialkyl carbonates and dialols. 16. Any of the processes under Responses 1 through 15 where cyclic carbonate contains ethylene carbonate and/or propylene carbonate, aliphatic monohydric alcohol contains methanol and/or ethanol, and separated dialkyl carbonate contains dimethyl carbonate and/or diethyl carbonate. 17. Dimethyl carbonate separated by any of the processes described in Rights 1 through 16, containing a halogen fraction not exceeding 0.1 parts per million. 18. Dimethyl carbonate separated by any of the processes described in Rights 1 through 16, containing no more than 1 part per billion of halogen. 19. Dimethyl carbonate pursuant to claim 17 or 18, containing not more than 0.1% by weight of aliphatic monohydric alcohol. 20. A continuous multistage distillation column, specifically column B, is used to separate a low-boiling point mixture AT containing dialkyl carbonate and aliphatic monohydric alcohols produced by distillation into top component BT, with aliphatic monohydric alcohols as the main component, and bottom component BB, with dialkyl carbonate as the main component. The low-boiling point mixture AT is obtained by introducing cyclic carbonate and aliphatic monohydric alcohols as starting materials, continuously feeding these starting materials into a continuous multistage distillation column A containing a homogeneous catalyst, reactive distillation in column A, continuous extraction of the high-boiling point mixture AB containing the diols produced from the bottom of the column in liquid form, and continuous extraction of the low-boiling point mixture AT containing the diols produced. From the side view of the distillation column in the figure is a gas, where the multistage continuous distillation column B is said to consist of: an extraction section with length L1 (cm) and inner diameter D1 (cm) and an inner layer containing the number of steps n1, and a bulk section with length L2 (cm) and inner diameter D2 (cm) and an inner layer containing the number of steps n2, where L1, D1, n1, L2, D2 and n2 satisfy the following formulas (1) to (8): 500<_L1<_3000 (1) 100<_D1<_1000 (2) 2<_L1/D1<_30 (3) 10<_n1<_40 (4) 100<_L2<_5000 (5) 50<_D2<_800 (6) 10<_L2/D2<_50 (7), and 35<_n2<_100 (8) 21. A continuous multistage distillation column pursuant to claim clause 20, where L1, D1, L1/D1, n1, L2, D2, L2/D2 and n2 comply with 800<_L1<_2500, 120<_D1<_800, 5<_L1/D1<_20, 13<_n1<_25, 1500<_L2<_3500, 70<_D2<_600, 15<_L2/D2<_30, 40<_n2<_70, and D2<_/D1. 22. A continuous multistage distillation column pursuant to one of the claims in Clauses 20 through 21, whereby the inner layers of each section of the extraction and bulk sections of the continuous multistage distillation column B are trays and/or containers. 23. A continuous multi-stage distillation column pursuant to claim clause 22, where the inner layers of each section of the extraction and bulking sections are trays. 24. A continuous multi-stage distillation column pursuant to claim clause 23, where the trays are sieve trays. 25. A continuous multi-stage distillation column pursuant to claim 24, where the screening pans have 150 to 1200 holes/m² in their screening portion, and the cross-sectional area per hole is in the range of 0.5 to 5 cm². 26. The process pursuant to claim 24 or 25, where the sieve has 200 to 1100 holes/m² in its sieve section and the cross-sectional area per hole is in the range of 0.7 to 4 cm². 27. Any of the processes described in Articles 24 through 26 where the sieve has 250 to 1000 holes/m² in its sieve section and the cross-sectional area per hole is in the range of 0.9 to 3 cm².