Electrochemical Descriptors of the Catalytic Activity of Doped Molten Alkali Halide Salts for Methane Pyrolysis

Recent studies have shown that molten salts can serve as catalysts for methane pyrolysis. Molten alkali chlorides are poor catalysts for pyrolysis but can be activated by the addition of small amounts of salts that contain a reducible cation such as TiCl4 or CrCl3. The activation mechanism involves the back and forth conversion of Ti4+ to Ti3+ or of Cr3+ to Cr2+, caused by thermal fluctuations in the positions of the ions. In this article, we show that there is a correlation between the open cell voltage (OCV) in an electrochemical cell based on these redox couplings and the catalytic activity for pyrolysis. Thus, electrochemical measurements can be used to screen for good pyrolysis activity with doped molten salts.