Sorption enhanced steam reforming of ethanol over Ni-based catalyst coupling with high-performance CaO pellets

Abstract

Coupling with the conventional Ni/Al2O3 catalyst, novel CaO-based porous spherical sorbents (made by a new molding technique) were examined in the sorption enhanced steam reforming of ethanol process (SESRE) to improve the H2 quality. The cyclic H2 quality was monitored, and the catalytic properties of the catalyst for steam reforming of ethanol as well as the CO2 capture capacity of the modeled sorbents were studied in details. Besides, thermodynamic modelling has been done by Gibbs free energy minimization method to simulate the sorption enhancing effect and screen the optimized reaction conditions to yield high-quality H2; furthermore, the relative H2O consumption versus ethanol during the reforming process was further discussed. The results showed that the sorption enhanced steam reforming process was an effective and flexible way to produce high-quality H2 around 600 °C, and subsequently the simulated sorption enhanced process was validated experimentally. In addition, the properties of the catalyst and modeled sorbents were analyzed by N2 physisorption, SEM, EDS-Mapping, H2-TPR, XRD, Raman, In-situ DRIFTS and so on. A high purity H2 was yielded during the pre-breakthrough stages, in especial that process enhanced by the modeled sorbents templated by cellules (CaOS-C5 pellets), which illustrated a good prospect of SESRE process. With the CaOS-C5 pellets, during the 10th SESRE process, H2 could be constantly produced with purity above 90% within at least 15 min of SESRE process. The modeled CaO spheres greatly boosted the concentration and output of H2. Over the repeated cycles, the Ni/Al2O3 catalyst and the modeled sorbents displayed well stability over the long-term reactions, which illustrated a good prospect of SESRE process enhanced by these new spherical sorbents.