Enhanced hydrogen production by in situ CO2 removal on CaCeZrOx nanocrystals

The CO2 capture properties of a new nanocrystalline CaO-based mixed oxide (CaCeZrOx) were studied in both TGA and a fixed bed reactor. The kinetics of CO2 capture at dry conditions was compared between these two reactors. The application of the new CO2 acceptor in sorption enhanced steam methane reforming was studied by a fixed-bed reactor in the presence of 40 wt% nickel hydrotalcite catalysts. Experimental results show that the new CO2 acceptor, CaCeZrOx has a significantly improved CO2 capture capacity and cyclic reaction stability compared to natural dolomites, because of the large pores and stable backbone structure. It has also been observed that the sorption enhanced steam methane reforming in the fixed bed reactor produces more than 95% H2 in a single-step process. Increase in production of hydrogen and higher CO2 capture capacity are also observed with an increase in the residence time of methane. Steam has a significant effect on the stability of the acceptors, but not very much on the kinetics and capacity of CO2 capture. The capacity of CO2 capture on the acceptors in the SESMR process cannot be predicted by the independent CO2 capture kinetic study on acceptor alone. A synergy effect between the sorption enhanced reactions and CO2 capture on the CO2 capture capacity was observed on the all solid CaO based CO2 acceptors.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (121 K)Download as PowerPoint slideHighlights► New nanocrystalline CaCeZrOx as a good CO2 acceptor. ► High CO2 capture capacity and cycle good stability. ► Fast carbonation and good stability in sorption enhanced methane reforming. ► A synergy between sorption enhanced reforming and carbonation on CO2 capacity.