Patent Report: Saudi company earns patent for chemical recycling

Depolymerization. The U.S. Patent and Trademark Office has awarded a patent to the Saudi Arabian Oil Co., Dharan, for a process that recycles used plastics by breaking them down into various chemicals, such as light olefins, benzene, toluene and xylene.  

The new method involves dissolving the waste polymers using an aromatic-rich solvent and then catalytically cracking them in a reactor. The method can be used to process PE, PET, PS, polyolefins, PP, PVC, polyamide, PC, PU, polyester, natural rubber, synthetic rubber and various combinations of these polymers.  

In one embodiment of the invention, the reactor is operated at temperatures between 1,022 degrees Fahrenheit and 1,202 degrees Fahrenheit and the dissolved polymer solution has a residence time in the reactor of no more than 1 second.  

The invention has advantages over other depolymerization methods, such as delayed coking, pyrolysis, gasification and liquefaction, because it produces less waste, is more economical and doesn’t introduce contaminants such as sulfur and nitrogen, according to the patent. The company is touting the development as an alternative to incinerating or landfilling plastic waste when conventional recycling methods are not economically feasible. 

Patent 11,104,851; issued Aug. 31