Bichloride-based ionic liquids for the merged storage, processing, and electrolysis of hydrogen chloride

Abstract

Hydrogen chloride is produced as a by-product in industrial processes on a million-ton scale. Since HCl is inherently dangerous, its storage and transport are avoided by, e.g., on-site electrolysis providing H 2 and Cl 2 which usually requires complex cell designs and PFAS-based membranes. Here we report a complementary approach to safely store 0.61 kilogram HCl per kilogram storage material [NEt 3 Me]Cl forming the bichloride [NEt 3 Me][Cl(HCl) n ]. Although HCl release is possible from this ionic liquid by heat or vacuum, the bichloride can be used directly to produce base chemicals like vinyl chloride. Alternatively, [NEt 3 Me][Cl(HCl) n ] is electrolyzed under anhydrous conditions using a membrane-free cell to generate H 2 and the corresponding chlorination agent [NEt 3 Me][Cl(Cl 2 ) n ], enabling the combination of these ionic liquids for the production of base chemicals.