TH89673A - Processes for industrial production dialkyl carbonates and diol - Google Patents

Abstract

DC60 The purpose of this invention is to provide a specific process capable of producing alkyl carbonates and diols on an industrial scale of not less than 2 tons/hour and not less than 1.3 tons/hour, respectively, with high specificity and consistently high yield over long periods via a reactive distillation system using cyclic carbonates and aliphatic monohydric alcohols as feedstocks, where the feedstocks are continuously fed into a continuous multistage distillation column containing a catalyst, and the reaction and distillation are carried out simultaneously within the column. Although many proposals exist for the production of diakyl carbonates and diols via reactive distillation, these have been limited to small-scale, short-duration laboratory operations, and nothing has been disclosed regarding a specific process or apparatus capable of mass production on an industrial scale. This invention provides a continuous multistage distillation column with a specific structure and a production process using the continuous multistage distillation column accordingly, for the production of diakyl carbonates. And diols can be produced on an industrial scale of not less than 2 tons/hour and not less than 1.3 tons/hour, respectively, with each having a specificity of not less than 95%, with an optimal of not less than 97%, and an optimal of not less than 99%, with a constant duration of not less than 1000 hours, with an optimal of not less than 3000 hours, and an optimal of not less than 5000 hours. The objective of this invention is to provide a specific process capable of producing alkyl carbonates and diols on an industrial scale of not less than 2 tons/hour and not less than 1.3 tons/hour, respectively, with high specificity and consistently high yield over a period of time through a reactive distillation system using cyclic carbonate and aliphatic monohydric alcohols as feedstocks, where the feedstocks are continuously fed into a continuous multistage distillation column containing a catalyst, and the reaction and distillation are carried out simultaneously in the column. Although many proposals exist for processes for the production of dialkyl carbonates. Although diols are produced by reactive distillation, they are only available at small scales and with short laboratory processing times. Furthermore, no specific process or equipment capable of mass production at industrial scale has been disclosed. This invention provides for a specific structured, continuous multistage distillation column and a production process utilizing this column. Accordingly, dialkyl carbonates and diols can be produced at industrial scales of not less than 2 tons/hour and not less than 1.3 tons/hour, respectively, with each having a specificity of not less than 95%, an optimal of not less than 97%, and an optimal of not less than 99%, with a sustained period of not less than 1000 hours, an optimal of not less than 3000 hours, and an optimal of not less than 5000 hours.

Claims (11)

1. The process for the industrial production of dialkyl carbonates and diols in which dialkyl carbonates and diols are continuously produced via a reactive distillation system using cyclic carbonates and aliphatic monohydric alcohols as feedstocks, consisting of the following steps: continuous feeding of the feedstocks into a continuous multistage distillation column containing a catalyst; simultaneous reaction and distillation in the column; continuous extraction of the low-boiling point reaction mixture consisting of alkyl carbonates produced from the top of the column in gaseous form; and continuous extraction of the high-boiling point reaction mixture consisting of diols from the bottom of the column in liquid form, where (a) the continuous multistage distillation column consists of a tray column with a cylindrical nozzle of length L (cm) and inner diameter D (cm) and has an internal structure of inner layers of n stages, such inner layers being trays with more than one number of holes. There is also a gas outlet with an inner diameter d1 (cm) at the top of the tower or the upper part of the tower near the top; a liquid outlet with an inner diameter d2 (cm) at the end of the tower or the lower part of the tower near the end; at least one first inlet provided in the upper and/or middle part of the tower below the gas outlet; and at least one second inlet provided in the middle and/or lower part. The ratio of the length L (cm) of the tower to the inner diameter d1 (cm) of the gas outlet is given by formula (1); 2100 is less than or equal to L ≤ 8000 (1). (2) The ratio of the inner diameter D (cm) of the tower to the inner diameter d1 (cm) of the gas outlet is given by formula (2); 180 is less than or equal to D ≤ 2000 (2). (3) The ratio of the length L (cm) to the inner diameter D (cm) of the tower is given by formula (3); 4 is less than or equal to L/D ≤ 40 (3). (4) The number of steps n is given by formula (4); 10 is less than or equal to n ≤ 120 (4). (5) The ratio of the inner diameter D (cm) of the tower to the inner diameter d1 (cm) of the gas outlet is given by formula (5); 3 is less than or equal to D/d1 ≤ 20 (5). And (6) The ratio of the inner diameter D (cm) of the tower to the inner diameter d1 (cm) of the gas outlet is given by formula (5); 3 is less than or equal to D/d1 ≤ 20 (5). (b) The ratio of the volume produced P (starts/hour) of dialkyl carbonate to the total pore area S (m²) of more than one pore appearing in one tray stage corresponds to the formula (7). 10 ≤ P/S ≤ 100 (7) 2. The process under Claim 1, where the quantity of dialkyl carbonate produced is not less than 2 tons/hour. 3. The process under claim 1 or 2, where the quantity of dialol produced is not less than 1.3 tons/hour. 4. The process according to any one of the claims of 1 to 3, where d1 and d2 correspond to formula (8); 1 is less than or equal to d1/d2 is less than or equal to 5 (8). 5. The process according to any one of claims 1 through 4, where L, D, L/D, n, D/d1, and D/d2 for a continuous multistage distillation column correspond to the following formulas; 2300 ≤ L ≤ 6000, 200 ≤ D ≤ 1000, 5 ≤ L/D ≤ 30, 30 ≤ n ≤ 100, 4 ≤ D/d1 ≤ 15, and 7 ≤ D/d2 ≤ 25, respectively. 6. The process according to any one of claims 1 through 5, where L, D, L/D, n, D/d1, D/d2 for a continuous multistage distillation column corresponds to the following formulas; 2500 ≤ L ≤ 5000, 210 ≤ D ≤ 800, 7 ≤ L/D ≤ 20, 40 ≤ n ≤ 90, 5 ≤ D/d1 ≤ 13, and 9 ≤ D/d2 ≤ 20, respectively. 7. The process according to any one of the claims 1 through 6, where P/S corresponds to the following formula: 15 ≤ or equal to P/S ≤ or equal to 80. 8. The process according to claim 7, where P/S corresponds to the following formula: 20 ≤ or equal to P/S ≤ or equal to 70. 9. The process under any one of the claims 1 through 8, where the tray is a sieve tray with a sieve section and a falling section. 10. The process pursuant to claim 9, where the sieve has 100 to 1000 holes/m² in the sieve portion of the thing. 11. The process pursuant to claim 9 or 10, where the cross-sectional area of the sieve tray is in the range of 0.5 to 5 cm².