Core-shell structured CaO-Ca9Al6O18@Ca5Al6O14/Ni bifunctional material for sorption-enhanced steam methane reforming

- Core-shell structured “reforming-adsorption” bifunctional materials were prepared.
- The core and shell materials were CaO-Ca9Al6O18 and Ni/Ca5Al6O14, respectively.
- The stabilization effect of Ca9Al6O18 and the support effect of Ca5Al6O14 existed.
- The core-shell materials showed high activity and stability in the SESMR process.
- The best material displayed about 100% of CaO utilization during 60 SESMR cycles.

Sorption-enhanced steam methane reforming (SESMR) is a promising technology for H2 production, which can be further enhanced at the particle scale by using core (sorbent)-shell (catalyst) structured bifunctional materials. However, it is challenging but desirable to develop such materials with high activity and stability. In this work, three core-shell structured CaO-Ca9Al6O18@Ca5Al6O14/Ni bifunctional materials with varying CaO content and core/shell mass ratio were prepared by a two-step sol-gel method, and two others (Ni/CaO and CaO@Ca5Al6O14/Ni) served as references. The structural properties and catalytic performance of the materials were investigated. The results showed that all core-shell materials during cyclic SESMR operation had much better performance than Ni/CaO with regards to activity, stability and CaO utilization, and CaO-Ca9Al6O18@Ca5Al6O14/Ni was generally superior to CaO@Ca5Al6O14/Ni except when the former had a much higher CaO content than the latter. The excellent performance of CaO-Ca9Al6O18@Ca5Al6O14/Ni was mainly due to the stabilization effect of Ca9Al6O18 and the support effect of Ca5Al6O14. The best material was a CaO-Ca9Al6O18@Ca5Al6O14/Ni with a CaO content of 13 wt% and a core/shell mass ratio of 0.2, showing high activity and stability over 60 SESMR cycles while maintaining nearly complete utilization of CaO.

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