Evaluation of heterogeneous metal-sulfide molten salt slurry systems for hydrogen production through methane pyrolysis

Abstract

In this paper we evaluate the addition of suspended metal sulfides to molten salt slurry systems for methane pyrolysis. Stability tests are completed at 800 °C in eutectic molten sodium and potassium bromide for 6 h. In addition, the slurries are evaluated from 800 to 900 °C. It is demonstrated that the addition of metal sulfides does enhance hydrogen production over a 6-h stability test. MoS2 2-μm particles suspended in NaBr-KBr demonstrated 2.75% methane conversion at 800 °C with a 120 mm bubble path, with an apparent activation energy of 57 kJ mol−1. In addition, the MoS2 particles demonstrated good structural stability but deactivated primarily through coking in the melt. The experiments demonstrate the potential to reduce the operating temperature of molten salt methane pyrolysis, although there is notable instability. MoS2 in one run was observed to steadily decline from a peak of 2.84% methane conversion to 1.71% in 6 h. This instability is the result of coking; leaching is also observed in WS2 samples.