TARRAGONA, Spain—German materials supplier Covestro A.G. is planning to build its own chlorine production plant in Tarragona, using a homegrown sustainable process: Oxygen-depolarized cathode technology.
In a June 19 statement, the company said the industrial-scale plant will be based at its current production facility in Spain, and will consume around a quarter less energy than the conventional method.
Covestro said it is currently investing around $231.6 million at Tarragona to increase the site's competitiveness. The new chlorine production plant being a key part of the investment.
Construction of the new plant in Tarragona is scheduled to begin in the first half of 2019, and the chlorine produced there mainly will be sued to make MDI, a precursor for rigid foam.
"About one third of the production costs for chlorine are usually spent on energy. Thus, the selected technology makes an important economic contribution," Covestro explained.
According Chief Technology Officer Klaus Schaefer, the main reasons for choosing the process were sustainability and energy efficiency.
"This is a special success story for us since the development of this technology began at our company over two decades ago," Schaefer said.
Chlorine is needed to make around two-thirds of all polymers, yet it does not occur naturally in its pure form. Instead, it is found only in chemical compounds such as in rock salt, from which chlorine can be obtained using electrolysis, which is very energy-intesive.
However, Covestro, in partnership with Thyssenkrupp Uhde Chlorine Engineers, has developed a technology which it claims consumes around 25 percent less energy than conventional electrolysis through the use of an oxygen-depolarized cathode (ODC).
ODC technology is based on the conventional membrane process, in which chlorine, caustic soda and hydrogen usually are produced from rock salt and water.
The crucial difference, Covestro explained, is that the hydrogen-generating electrode normally used is replaced by an oxygen-depolarized cathode.
"Only chlorine and caustic soda are produced. As a result, a voltage of just around two instead of three volts is required," the company said.
"The change in this process sounds simple, but was a ground breaking development for chlorine manufacturing," said Hanno Bruemmer, head of production at the polyurethanes segment which includes the company's global chlorine activities.
Initial invention and development work on the process began in 1992, with the first demonstration plant on an industrial scale built in Krefeld-Uerdingen in 2011.