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This thesis investigates the design and performance of absorbent-enhanced ammonia synthesis reactors. The per-pass conversion of ammonia can be improved by the sequencing of ammonia synthesis catalyst and ammonia-selective absorbent beds in the reactor. A new perspective includes adjacent coupling and multi-bed coupled absorptive reactors which contributes to the exciting area of ammonia synthesis improvement. This type of reactors enable operation under conditions milder than those used in a traditional Haber-Bosch reactor. As part of the work a novel Ru catalyst with polar metallic oxide support was developed to meet the requirements of mild operating conditions of the absorptive reactor. An experimental unit was built to perform the synthesis of ammonia in a fixed-bed absorptive reactor, and an increased per-pass conversion was observed from experimental data. Mathematical models were also developed to provide insights into the reasons for the conversion improvement in the absorptive reactor. Our simulations of these two kinds of absorption-enhanced ammonia synthesis reactors contribute to their understanding and confirm the enhancement of their per-pass conversion. A preliminary mathematical model study of the adjacent coupling absorptive reactor was carried out first in which the influence of absorption on the per-pass ammonia conversion was linked to a hypothetical recycle stream. Based on the result of this preliminary model, a more detailed transient backflow cell model was developed to simulate the behaviour of the adjacent coupling absorptive reactor. Given the complexity of the reacting fluid through the fixed bed, a computational fluid dynamics simulation via ANSYS Fluent was also generated and resulted in similar results to those of the transient backflow cell model. On this basis, an improved absorptive reactor, i.e. the multi-bed absorptive reactor, was proposed and modelled in Fluent, achieving close to 100% per-pass conversion. This research improved the per-pass conversion of ammonia synthesis reactors and enabled milder operating conditions for process. Furthermore, a theoretical framework was provided through mathematical modelling for optimisation purposes.