Sorption-enhanced steam gasification of woody biomass assisted by Ca/Na/FS (fine slag) composite sorbents

In this research, composite sorbents with high activity in promoting H-2 production during sorption-enhanced steam gasification of pine sawdust (PS) were developed by doping coal gasification fine slag (FS) and NaOH into calcined conch shell (CS). The tests performed in a laboratory-scale fixed bed reactor demonstrated that the composite sorbents greatly improved H-2 concentration and yield over that achieved with CHCS (CS after hydration and calcination), reaching 73.5% and 600.7 mL/g-PS, respectively. This promotion effect on H-2 production was not influenced by the unburned carbon in FS. To obtain high H-2 concentration and yield with as little NaOH and as much FS as possible, the optimum sorbent was found to be 3CS-2FS-0.32Na (in mass ratio of CS:FS:NaOH = 3:2:0.32). Under this condition, the H-2 concentration and yield reached 74.3% and 572.3 mL/g-PS, respectively. In five cycles of experiment, although the H-2 yield of 3CS-2FS-0.32Na decreased from 572.3 mL/g-PS to 416.6 mL/g-PS, it was always higher than with CHCS alone by at least 28%. The results in this study indicate that FS has potential to be an effective inert support material that endows CaO with high activity in H-2 production during sorption-enhanced steam gasification. This might help to provide a new approach to minimizing the negative environmental impact of FS. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.