Process intensification of the NH3 synthesis through in situ removal: Exploring the potential of sorption-enhancement

The projected increase in demand for renewable-based ammonia (NH3) as hydrogen carrier or sustainable fuel stresses the need for efficient synthesis processes. The enhancement of the NH3 synthesis through in situ NH3 removal was identified as a promising process intensification strategy. This work aims to demonstrate the potential of the in situ removal based on reactor simulations and experimental investigations by applying the in situ sorption of NH3. A steady-state simulation study of NH3 synthesis combined with ideal separation was employed to predict the potential of enhancement in NH3 formation for an ideal benchmark case. The results show an increase in NH3 formation in both, the equilibrium and the kinetic regime of the synthesis reaction. Furthermore, experiments in a fixed-bed reactor filled with a commercial iron catalyst and activated carbon impregnated with manganese chloride as a sorbent were conducted in different arrangements of catalyst and sorbent beds to demonstrate the feasibility of simultaneous sorption and reaction under similar conditions. A significant increase in produced molar flow rate of NH3 was achieved through in situ sorptive removal, aligning well with model-based predictions. Hence, this work successfully highlights the potential of in situ NH3 removal under industrially relevant reaction conditions and thereby the envisaged process intensification strategy.