Reactions in the hydrogen production conversion system
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CH4 + H2O = CO + 3H2 ① CO + 3H2 = CH4 + H2O ΔH298 = -206 kJ/mol ② CO + H2O = CO2 + H2 ΔH298 = -41 kJ/mol ③ These are the reactions that occur in hydrogen production converters. I wonder whether, if the temperature is too high, reaction ② is more likely to take place If reaction ② occurs, will the reaction continue according to reaction ①?
Among them, equation ① is an endothermic reaction; the heat absorbed in it exceeds the total heat released by equations ② and ③. Therefore, the overall conversion process is an endothermic reaction. Reaction ① is an irreversible reaction, and the conversion equilibrium is determined by ② and ③. ②The methane in it will crack, which involves carbon precipitation and carbon removal
2 should be an exothermic reaction; higher temperatures favor reaction 1 and inhibit reaction 2, while later on it leads to reaction 3
Reaction 2 is a methanation reaction, which is an exothermic reaction. In the pre-conversion reactor, this reaction takes place. Because the pre-conversion temperature is relatively low, usually around 400 degrees. However, the temperature in the converter is very high, at 800–900°C at the outlet, which suppresses reaction 2.
The methanation reaction is a highly exothermic reaction; the high temperatures in the conversion furnace suppress this reaction, so it is only taken into consideration in hydrogenation reactors.