Process for the preparation of propylene carbonate
View Patent ↗The invention relates to a process for the preparation of propylene carbonate, which process involves contacting propylene oxide with carbon dioxide at a temperature of from 150° C. to 250° C. in the presence of a recycled tetraalkylphosphonium bromide catalyst.
1. A process for the preparation of a propylene carbonate, which process comprises contacting propylene oxide with carbon dioxide at a temperature of from 150° C. to 250° C. in the presence of a recycled tetraalkyl-phosphonium bromide catalyst of the formula R 1 R 2 R 3 R 4 PBr wherein each of R 1 , R 2 , R 3 , and R 4 are alkyl substituents.
2. A process of claim 1 , wherein a protogenic compound is present during the preparation of propylene carbonate.
3. The process of claim 1 , wherein the protogenic compound is an alcohol.
4. The process of claim 1 , wherein R 1 , R 2 , R 3 and R 4 represent identical alkyl groups.
5. The process of claim 1 , wherein the amount of tetraalkyl phosphonium bromide compound is from 0.0001 to 0.1 mole per mole of propylene oxide.
6. The process of claim 1 , wherein the preparation of propylene carbonate is conducted at a partial carbon dioxide pressure in the range of from 5 to 70×10 5 N/m 2 .
7. A process for the preparation of 1,2-propanediol, which process comprises:
(i) preparing a propylene carbonate as claimed in claim 1 to obtain a reaction mixture;
(ii) contacting the reaction mixture containing the propylene carbonate with water and/or alcohol in the presence of a heterogeneous catalyst to obtain 1,2-propanediol and optionally dialkylcarbonate; and,
(iii) separating the 1,2-propanediol and optionally dialkylcarbonate from the reaction mixture obtained.
8. The process of claim 7 , wherein in step (ii) the propylene carbonate is contacted with water to obtain 1,2-propanediol.
9. The process of claim 7 , wherein in step (iii) the tetraalkylphosphonium bromide catalyst is removed in combination with 1,2-propanediol, which catalyst and 1,2-propanediol are subsequently recycled to step (i).
10. The process of claim 7 , wherein a protogenic compound is present during the preparation of propylene carbonate.
11. The process of claim 10 , in which process the protogenic compound is an alcohol.
12. The process of claim 5 , wherein R 1 , R 2 , R 3 and R 4 represent identical alkyl groups.
13. The process of claim 7 , wherein the amount of tetraalkyl phosphonium bromide compound is from 0.0001 to 0.1 mole per mole of propylene oxide.
14. The process of claim 7 , wherein the preparation of propylene carbonate is conducted at a partial carbon dioxide pressure in the range of from 5 to 70×10 5 N/m 2 .