Is the polycarbonate production process at Bayer Shanghai based on the phosgene method or a phosgene-free method?
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I’ve looked up a lot of information, but I still can’t figure out what manufacturing process Bayer uses for polycarbonates in Shanghai Some say that its raw materials, DPC and bisphenol A, are both imported, and it is referred to as the non-phosgene method. Some say it is the phosgene method, while others say it is the transesterification method. Does anyone know?
Learn* it a bit; thanks for your hard work, OP!
Starting with DPC and bisphenol A, of course without phosgene.
In fact, the non-phosgene route means that phosgene is not used in the synthesis of either DPC or PC polymers.
It mainly depends on the synthesis process of DPC
As is well known, there are the PC phosgene interfacial method and the transesterification method. The phosgene interfacial method involves the reaction of bisphenol A with phosgene, and it belongs to the phosgene method. The transesterification method involves a reaction between bisphenol A and diphenyl carbonate (DPC). Depending on the synthesis method of DPC, it can be divided into the phosgene method (reaction between phosgene and phenol) and the non-phosgene method (whereadays, dimethyl carbonate (DMC) is mostly used in the reaction with phenol, and DMC is produced using the non-phosgene method). The Bayer Shanghai PC project uses the transesterification method; in the first phase, DPC is imported from abroad (claimed to be produced without the use of phosgene), which is why it is given the label of a phosgene-free process. In the second phase, a DPC unit using the phosgene method was installed. Therefore, the PC plant at Bayer Shanghai should be considered to use the phosgene process.
When will the polycarbonate production line at Bayer Shanghai Phase 2 come online? Does anyone know?
It is certain to be the phosgene method; for reference only
Now it’s finally clear: back then, to facilitate investment attraction, the phosgene-based process was located abroad while the raw materials were imported directly; as a result, during the first phase of construction, phosgene was not used, and it was falsely claimed that a phosgene-free method was being employed! During the second phase of the project, Bayer showed its true colors – why not produce the raw materials domestically instead of continuing to import them? Therefore, to ensure success in attracting investment, one can only adopt environmentally destructive technologies such as the phosgene method! Summary: It is a completely foreign-based elimination process—the phosgene method!
This post was last edited by plumtree on 2013-4-8 08:25. With a large number of such facilities being established in China, it’s likely that they still won’t be able to compete with BAYER – the costs are simply too high. By the way, for bisphenol A, are you planning to use Cisa’s?