Chemical reactor network modeling of a microwave plasma thermal decomposition of H2S into hydrogen and sulfur

The conventional treatment method for H2S is the Claus process, which produces sulfur and water. This results in a loss of the valuable potential product hydrogen. H2S treatment would be more economically valuable if both hydrogen and sulfur products could be recovered. Based on standard heats of formation analysis, the theoretical energy required to produce hydrogen from H2S dissociation is only 20.6 kJ/mol of H2 as compared to 63.2 kJ/mol of H2 from steam methane reforming and 285.8 kJ/mol of H2 from water electrolysis. Among the many thermal decomposition methods that have been explored in the literature, Micro-wave plasma dissociation of H2S prevails as the method of choice to attain the best conversion and energy efficiency. Chemical kinetics simulations using an ideal flow reactor network have been carried out on the CHEMKIN-PRO software package and they support these findings. The reactor network simulates the thermal plasma behavior in the plasma torch, the plasma reactor, and the sulfur condenser. Two chemical kinetics mechanisms have been used and the results show an almost complete conversion of H2S into hydrogen and sulfur in the plasma reactor at an optimum temperature of about 2400 K at atmospheric pressure. While the most challenging task of the process is found to be the plasma cooling rate at the sulfur condenser where very fast quenching is required to conserve the hydrogen product from converting back to H2S.

► Microwave plasma dissociation of H2S into hydrogen and sulfur has been simulated. ► Chemical reactor network is created to explore the reaction kinetics of the process. ► Optimal plasma reactor parameters are determined for best hydrogen production. ► Challenge is to design a fast thermal quenching process to conserve the products.