Experimental investigation and thermo-chemical modeling of methane pyrolysis in a liquid metal bubble column reactor with a packed bed

• Methane pyrolysis in a liquid metal bubble column with a packed bed.
• 30% maximum hydrogen yield at 50 mln/min methane volume flow rate and 1273 K.
• New experimental setup without tin corrosion issues.
• Carbon accumulated on top of the liquid metal interface without clogging issues.
• Thermo-chemical model predictions are in line with the experimental results.

The decomposition of methane in a bubble column reactor, filled with tin, in combination with a packed bed, was investigated at different liquid metal temperature levels. All experiments were conducted with a methane feed gas volume flow rate in the range of 50–200 mln/min at temperatures up to 1273 K. The maximum hydrogen yield was 30% at 50 mln/min methane volume flow rate and a temperature level of 1273 K. The main components measured in the product gas were methane and hydrogen, intermediates were detected only in small amounts of less than 1.6 mol-%. The produced carbon was mainly accumulated as powder on top of the liquid metal interface. Within the liquid metal, only a thin carbon layer was deposited on the reactor wall. During the experiments, clogging issues due to solid carbon layers at the reactor wall did not occur. A thermo-chemical model was developed and implemented, taking into account the influence of the adjustable operating conditions as well as an experimentally determined gas residence time. Using the thermo-chemical model, a sensitivity analysis of the most dominant process parameters was performed, indicating that temperature and gas residence time have the strongest influence on the process. The model predictions were compared with the experimental results.