Process for producing aromatic carbonates
View Patent ↗This invention provides a method for producing an alkylaryl carbonate comprising: a) contacting a stream comprising an aromatic hydroxy compound and a stream comprising a dialkylcarbonate in a reactive distillation column containing a bed of heterogeneous transesterification catalyst, the bed having a top and a bottom; and b) withdrawing a product stream comprising the alkylaryl carbonate from the reactive distillation column wherein the aromatic hydroxy compound is fed to the column at a first feed point located above the top of the catalyst bed.
1. A method for producing an alkylaryl carbonate comprising:
a) contacting a stream comprising an aromatic hydroxy compound and water, and a stream comprising a dialkylcarbonate in a reactive distillation column containing a bed of heterogeneous transesterification catalyst, the bed having a top and a bottom; and
b) withdrawing a product stream comprising the alkylaryl carbonate from the reactive distillation column
wherein the aromatic hydroxy compound is fed to the column at a first feed point located at least one theoretical tray above the top of the catalyst bed; wherein the aromatic hydroxy compound has a water content of less than 0.5 wt % when it first contacts the top of the heterogeneous transesterification catalyst bed.
2. A method as claimed in claim 1 where the reactive distillation column contains an item selected from the group consisting of trays and packing between the top of the catalyst bed and the first feed point.
3. A method as claimed in claim 1 where the reactive distillation column contains a second catalyst bed between the top of the catalyst bed and the first feed point.
4. A method as claimed in claim 3 wherein the second catalyst accelerates the reaction of water with dialkylcarbonate.
5. A method as claimed in claim 1 further comprising feeding a homogeneous transesterification catalyst to the reactive distillation column.
6. A method as claimed in claim 5 wherein the homogeneous transesterification catalyst is fed to the column at a point below the first feed point.
7. A method as claimed in claim 1 wherein the aromatic hydroxy compound is phenol.
8. A method as claimed in claim 1 wherein the dialkylcarbonate is selected from the group consisting of dimethyl carbonate, diethyl carbonate and mixtures thereof.
9. A method as claimed in claim 1 wherein the dialkylcarbonate is fed to the reactive distillation column at a point below the top of the catalyst bed.
10. A method as claimed in claim 1 wherein the dialkylcarbonate is fed to the reactive distillation column at a point below the bottom of the catalyst bed.
11. A method as claimed in claim 1 wherein the heterogeneous catalyst comprises titanium.
12. A method as claimed in claim 1 wherein the aromatic hydroxy compound has a water content of less than 500 ppmw when it first contacts the top of the heterogeneous transesterification catalyst bed.