A MATHEMATICAL-MODEL OF A CATALYTIC MEMBRANE REACTOR FOR THE DECOMPOSITION OF NH3

Catalytic NH3 decomposition in the gas feed to the turbine is a potential method for reducing NO(x) emissions in coal gasification power plants. Since the decomposition reaction is equilibrium limited at gasification conditions, a membrane reactor is necessary to achieve a high conversion of NH3 to N2 and H-2. The objective of this study was to use a mathematical model to investigate catalytic NH3 decomposition in a membrane reactor for both countercurrent and cocurrent flow configurations. The cocurrent flow configuration was generally better in membrane reactors with Knudsen diffusion selectivities. The choice between cocurrent and countercurrent flow for membranes that are more selective for H-2 depends on operating conditions. To achieve the high NH3 conversion desired in this study, a membrane with a selectivity for H-2 over N2 of greater than 50 is needed. The model used in this study accounts for the influence of interphase and intraparticle mass transfer resistance on membrane reactor performance. These mass transfer resistances are a concern in this study because NH3 is present at dilute concentrations.