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The kinetics of CO2-capture on Li4SiO4 has been examined experimentally and described by a mathematical reaction-rate model. Sorption-enhanced steam methane reforming has been simulated with a fixed-bed reactor model using the formulated capture kinetics. At working conditions of 20 bar, 848 K, a steam-to-carbon ratio of 5, and a superficial inlet gas velocity of 1 m/s, a dry hydrogen mole fraction at the outlet of 0.87 can be reached. The performance of the process with Li4SiO4 is compared to that with Li2ZrO3 as CO2-acceptor. Li4SiO4 gives higher conversion and production capacity at lower steam-to-carbon ratios. A drawback for the process with Li4SiO4 as acceptor is that high conversion is only reached at low fractional conversion of the acceptor. This is due to the fact that the capture kinetics is second order with respect to unreacted solid. The total reaction is endothermic, and effective heat exchange is necessary to avoid a dramatic drop in the reactor temperature. A fluidized-bed reactor has also been simulated, and the results have been compared to those of the fixed-bed reactor. The fluidized-bed reactor has some advantages in terms of easier heat integration and continuous regeneration of CO2-acceptor, but compared to the fixed bed, a longer reactor is needed to reach the same conversion.

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This paper discusses simulations of reactive flows in a two-dimensional cylindrical bubbling fluidized bed reactor by using an Eulerian modeling approach. The study is intended to elucidate some aspects of high relevance for the development of novel concepts in the area of hydrogen production by means of steam methane reforming (SMR). The work is initiated with a practical model validation of reactive gas-solid flows with simulations of laboratory-scale experiments of the ozone decomposition reaction. The predicted outlet concentrations for various fluidization velocities are in very good agreement with reported experimental data. Further, investigations of sorption enhanced steam methane reforming (SE-SMR) in bubbling fluidized beds are conducted with lithium zirconate as the CO 2 adsorbent. As long as extensive gas mixing is avoided, wide reactors are the most favorable choice for industrial applications since variations in bed diameter have a minor influence on the outlet hydrogen concentration. Running the process at elevated operating pressures and/or higher fluidization velocities requires increased bed heights. The most interesting finding of this work is the demonstration of how internal circulation and spatial temperature variations affect the reactor performance.

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