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A novel fluidized bed membrane reactor has been developed for the production of high-purity hydrogen based on steam methane reforming (SMR). The reactor incorporates perm-selective membranes for in-situ removal of hydrogen from the reactor, thus shifting the thermodynamic equilibrium of the SMR reaction. The membranes also eliminate the need for downstream hydrogen purification.The endothermic reaction duty is provided either by external heating of the vessel wall or through direct air injection into the fluidized catalyst bed (autothermal reforming). The gas flow pattern within the fluidized bed induces internal circulation of catalyst particles between the central reaction (permeation) zone and outer heating zones. The circulating hot catalyst particles from the oxidation zone carry the required endothermic heat of reaction for the reforming while ensuring that the palladium membranes are not exposed to high temperatures or to oxygen. Another characteristic of the reactor configuration is that very little of the nitrogen present in the oxidation air reaches the reaction zone, thus maintaining the hydrogen driving force for the perm-selective membranes.The reactor concept was proven in a pilot reactor (0.13 m diameter, 2.3 m tall). A number of variables were studied, including steam-to-carbon ratio, temperature and pressure. The pilot reactor was operated with both external heating and direct air addition. Pure hydrogen (99.999+%) was obtained from the reactor and an equilibrium shift was demonstrated. The maximum pure hydrogen recovery obtained from the pilot reactor was 0.96 mol H2/mol CH4, limited by the installed membrane surface area for these tests.

An industrial reactive separation process for NO x absorption into water and nitric acid in a world-scale mononitrobenzene (MNB) plant in Redcar, U.K., was investigated. Gas- and liquid-phase concentrations were measured in situ, while operating conditions such as temperature, pressure, and absorbent flow were varied. Furthermore, a comprehensive mass transfer/reaction model was developed in the process simulator Aspen Plus to simulate the absorption process, with the field process data used for validation. The model accurately predicted NO x removal from the gas (i.e., typically within 3.5% of the plant data). Other key findings are that the model successfully predicted changes in performance when key parameters such as temperature and pressure were varied. Furthermore, addition of a bleaching section was investigated, resulting in a significant improvement in NO x removal. Currently, the completed model is used to simulate existing and proposed NO x absorption systems and to develop new and innovative designs for NO x capture.