Adsorptive reactors represent an important class of multifunctional reactors, which provide much potential for process intensification (Stankiewicz, 2003). Such hybrid configurations may substantially improve reactant conversion or product selectivity and, for reversible reactions, establish more favourable reaction equilibrium than that could be achieved under conventional reactor operation. This work deals with the theoretical study of an alternative process for hydrogen production through steam methane reforming (SMR), based on the concept of adsorption-enhanced reaction. . Unlike previous studies in this area (Hufton et al., 1999; Stepanek et al., 1999; Ding and Alpay, 2000; Waldron et al., 2001), the continuous flow of adsorbent within a packed or structured reactor is proposed. Hence, this process can be regarded as the adsorptive reactor equivalent of the fluid catalytic cracking (FCC) process, but in this case the transported medium is the adsorbent. Similar to the FCC process, the benefits of this process are expected to be significant, with the excellent control of adsorbent residence time, the continuous supply of feed to a single unit, the enhanced mass and heat transfer, and an integrated energy supply system. The newly proposed process consists of a reactor/adsorber unit and regeneration (desorption) unit. The novelty of this approach is the use of a stationary SMR catalyst phase, through which adsorbent flows for the inŠsitu and selective removal of carbon dioxide. Such CO₂ removal results in favourable shifts in the reaction equilibria of both the reforming and water-gas shift reactions towards further carbon dioxide production. Furthermore, the reaction can be carried out at a moderate temperature range of 400-500^oC, which is considerably less than that of the conventional SMR process (>800^oC). Adsorbent regeneration is carried out ex-situ, and hot regenerated adsorbent passed back to the reactor unit. Thus, the reaction heat may also be supplied in a direct manner. As a result, a continuous, energy-integrated process is enabled, in which high purity hydrogen at the reactor pressure is produced. A non- isothermal mathematical model, accounting for general reaction kinetics, mass transfer limited adsorption kinetics and non-linear (Langmuirian) adsorption equilibria, has been developed. Particular attention has been given to the evaluation of effective gas-catalyst and gas-adsorbent contact, and therefore effective sorption-enhanced reaction. As a result, the nature of the stationary phase is of great importance. Specifically, packed bed and monolith catalyst structures have been considered. The modelling studies are supportive of the pilot-scale reactor experiments on gas-solid two-phase mixture flow through such structures by our collaborators at the University of Leeds (Wang et al., 2004; Ding et al., 2005). The work has also enabled the evaluation of the feasibility of new adsorbent materials currently being developed by our collaborators at the University of Bath. Particularly, two types of CO₂ adsorbent have been considered, an hydrotalcite and a lithium zirconate based one. Simulation results indicate the feasibility of this process concept. The results also provide evidence for the use of monolithic reactor as an adsorptive reactor. The determination of key design and operating parameters, such as reactor dimensions and temperature, superficial gas velocity and adsorbent mass flux, has been enabled by adopting a model-based process optimisation approach. This is essential in order to investigate the optimal energy integration between reaction and regeneration stages of the process. As a system with thermally coupled recycle, there is much potential for interesting dynamic behaviour. The model is also used to explore this and perform a stability analysis.

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