Bayer MaterialScience plans to build a chlorine recycling plant at the Bayer Integrated Site Shanghai (BISS). The process for this new unit is based on the catalytic oxidation of hydrogen chloride using oxygen. The new technology has been developed by the Japanese company Sumitomo Chemical Co., Ltd., and was licensed to Bayer MaterialScience. The plant will ensure the chlorine supply of the new 250,000 tpa toluene diisocyanate (TDI) facility in Shanghai. Bayer MaterialScience has recently broken ground for this new plant, which is based on the company's innovative gas phase phosgenation process and is scheduled to come on stream in 2010. The new chlorine recycling technology was awarded the prestigious Green & Sustainable Chemistry Award in Japan for being both energy-efficient and environmentally friendly. It enables a reduction in energy consumption of more than half versus the conventional process.
The process will take hydrogen chloride co-produced during the manufacture of isocyanates, and will convert it to chlorine which is re-used as raw material. During the past years, Sumitomo Chemical has enhanced the process and proven its technical viability in combination with already operating manufacturing plants. At BISS, Bayer MaterialScience has just started a new hydrochloric acid electrolysis plant to supply the 350,000 tpa diphenylmethane diisocyanate (MDI) train with chlorine. It uses the energy saving Oxygen Depolarized Cathode technology, which has been developed by Bayer and partners.