CuCrO2 Delafossite: A Stable Copper Catalyst for Chlorine Production

摘要

Around 1870, Henry Deacon discovered a process to valorize the large amounts of gaseous HC1, originating as a by-product of the Leblanc process, by catalytic oxidation to Cl2, which was used to make bleaching powder. Employing a pumice-supported CuCl2 catalyst in a fixed-bed reactor, the Deacon process constituted the first large-scale application of heterogeneous catalysis and one of the first examples in industry of the "waste-to-product" approach.12' This process did not last long in industry because the Leblanc process for Na2CO3 production was superseded by the less wasteful Solvay process, and with the development of suitable generators at the end of the 19th century, Cl2 was exclusively manufactured by NaCl electrolysis. The story now repeats itself, 140 years after Deacon. Currently, the recycling of by-product HC1 from phosgenation processes (e.g. polyurethane and polycarbonates production) by conversion to Cl2 is in high demand. However, neither the original Deacon catalyst, nor the multitude of (promoted) Cu-based systems developed during the 20th century offer a feasible solution, because they deactivate rapidly owing to the volatilization of copper chlorides under the reaction conditions. Any copper-based catalyst reported to date suffers from fast bulk chlorination, leading to volatile CuCl2 and CuCl, which translate into short catalyst lifetimes and severe corrosion issues in the plant.