Methane pyrolysis on sponge iron powder for sustainable hydrogen production

Abstract

Methane pyrolysis is one of the possible methods to produce low-carbon hydrogen. One of the most promising catalysts for methane pyrolysis is Fe due to its availability, relatively low cost and high working temperature. In the presented paper, the methane pyrolysis on unsupported (without a carrier) sponge iron in the form of powder was studied in the temperature range of 700–1100 °C. Methane pyrolysis was carried out in a stainless-steel tube reactor with an inner diameter of 10 mm. The reactor was heated locally by propane burner, the length of the heated zone was about 8 cm along the reactor tube. Methane feed rates were about 50, 100, and 200 ml/min, and the residence time of methane in the 8 cm long reaction zone was about 4, 2 and 1 s, respectively. The hydrogen yield increased with an increase in the temperature and a decrease in methane feed rate. At 700–800 °C, the hydrogen yield did not exceed 20%. At 900 °C, the yield reached 28.6% at a residence time of about 4 s. At 1000 °C, hydrogen yield was about 40 and 66.5% at a residence time of about 1 and 4 s, respectively. At 1100 °C, hydrogen yield varied in the range of 70–85%. The use of a catalyst increased the hydrogen yield by 81% compared to the experiment without a catalyst at 1100 °C. The catalytic effect of sponge iron powder can be used in the development of methane pyrolysis plants.