The Polimeri/Lummus process is a phosgene-free route for the production of diphenyl carbonate (DPC)—a polycarbonate intermediate from dimethyl carbonate (DMC) and phenol. The Polimeri/Lummus DPC process has no environmental or corrosion problems, and the byproduct methanol can be recycled back to the DMC process.
DMC and phenol are reacted to produce DPC and methanol. DPC is produced in two steps: phenol and DMC react to form phenylmethyl carbonate (PMC), followed by PMC disproportionation to DPC. Phenol, DMC and catalyst are fed to the PMC reaction section (1) where a small amount of anisole and CO2 are also produced. A “light” stream, containing mainly methanol, DMC and anisole, is fed to the azeotropic distillation section (2), from which a methanol-DMC azeotrope is recycled back to the DMC unit, some DMC is recycled to the PMC reaction section, and an anisole/DMC mixture is sent to the anisole recovery section (3).
A “heavy” stream, containing mainly PMC and phenol, is fed to the DPC reaction section (4) where disproportionation to DPC occurs. Unreacted phenol is recycled to the PMC section, while the balance is sent to the catalyst recovery area (5) from where recovered catalyst is also sent back to the PMC section. DPC is then purified (6) of any residual heavies.
Since Lummus also offers the Polimeri/Lummus DMC process, there are opportunities for energy integration between the DMC and DPC units.
Licensor: Lummus Technology