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 a 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. Therefore, experiments in a fixed bed reactor filled with a commercial iron catalyst and activated carbon impregnated with manganese chloride as a sorbent were conducted. Modelling of NH3 synthesis, including an ideal separation, allowed the prediction of increase in the NH3 yield, showing potential effects in both, the equilibrium and the kinetic regime of the synthesis reaction. Experiments investigating the formation of NH3 in different arrangements of catalyst and sorbent beds demonstrated the feasibility of sorption under reaction conditions with the selected sorbent. Further, an up to 30 % increase in NH3 yield through in situ sorptive removal, aligning well with model-based predictions, was observed in the respective experiments. Concludingly, this work demonstrates the positive effect of in situ NH3 removal under industrially relevant reaction conditions, confirming the potential of the selected catalyst and sorbent for the targeted process intensification.