Method for producing diaryl carbonate
View Patent ↗The present application relates to a method for the continuous production of diaryl carbonate from phosgene and of at least one monohydroxy compound (monophenol) in the presence of catalysts, and to the use thereof for the production of polycarbonates.
1. A process for preparing diaryl carbonate by reaction of an aromatic hydroxyl compound and a halogenated carbonyl in the presence of a catalyst in a reactor, wherein the halogenated carbonyl is passed into the reactor dissolved or in the liquid phase and wherein the ratio G/A is less than 0.010, where G is the entry volume flow rate of the liquid or dissolved halogenated carbonyl in m 3 /s and A is the internal cross-sectional area orthogonal to the longitudinal axis in m 2 , and wherein the reactor is at least one bubble column reactor.
2. The process as claimed in claim 1 , wherein the reaction takes place in a bubble column reactor in the absence of a solvent.
3. The process as claimed in claim 1 , wherein G/A is in the range from 0.0005 [m/s] and 0.0095 [m/s].
4. The process as claimed in claim 1 , wherein the ratio H/D is greater than or equal to 2 and H is the height of the liquid phase in the reactor in the gas-free state and D is the diameter of the reactor.
5. The process as claimed in claim 1 , wherein the residence time in the reactor is in the range from 0.5 to 4 hours, the temperature is in the range from 120 to 220° C. and the pressure is 3 to 100 bar.
6. The process as claimed in claim 1 , wherein the halogenated carbonyl is phosgene.
7. The process as claimed in claim 1 , wherein the aromatic hydroxyl compound is phenol.
8. The process as claimed in claim 1 , wherein the catalyst is pyridine, pyridine*HCl, TiCl 4 , Ti(OPh) 4 or AlCl 3 .
9. The process as claimed in claim 1 , wherein the process is conducted in at least two stages.
10. The process as claimed in claim 1 , wherein the reactor contains a liquid phase and an outlet in the liquid phase, and wherein the phosgene content at the reactor outlet in the liquid phase is less than 100 ppm.