Ammonia Decomposition

Signature redacted for privacy. Abstract approved: (.-i_I c(Dr. J Douglas Wa The purpose of this research is to study the feasibility of combining reaction and separation in a membrane separation unit. The asymmetric ceramic membrane reactor applied to the gas-phase catalytic decomposition reaction of ammonia from an IGCC (Integrated Gasification Combined Cycle Processes) gas mixture was simulated in the temperature range of 810-1366 K and over the pressure range of 18.248E5-35.482E5 Pa. The assumptions for the development of the model equations were plug flow on both sides of the membrane, negligible reverse reaction, and negligible heat and mass transfer resistance in the catalyst. A mass balance over a differential volume of the reactor gives eight simultaneous ordinary differential equations for four gas components. These equations were solved simultaneously as an initial value problem using the DIVPAG subroutine(Gear'S method) from the IMSL Math Library. The conversion for ammonia decomposition was successfully increased beyond the value obtained in a plug flow reactor by removing the product from the reaction zone via Knudsen diffusion through reactor walls. The general behavior of the membrane reactor and the plug flow reactor are compared from the viewpoint of equilibrium conversion shift. Decreasing the pressure ratio and increasing the total flow rate of the sweep gas in the separation side contributed to the higher conversion shift. The optimum thickness of the ceramic membrane selective layer was found to be in the range of 3-9 pm. The fractional conversion of membrane reactor is always greater than plug flow reactor. This work was supported by a subcontract from the U.S