Iron-based composite oxygen carrier (OC) (Fe4ATP6K1) was prepared by sol-gel method

which features Fe2O3 as an active component

and natural attapugite (ATP) as an inert support

as well as being modified by KNO3. Effects of reaction temperature

flow rate of steam and molar ratio of O/C on chemical looping gasification (CLG) of coffee grounds were investigated in a high temperature fluidized bed using steam as gasification agent. It suggests that the Fe4ATP6K1 oxygen carrier as bed material could facilitate carbon conversion in CLG of coffee grounds from 71.38% to 86.25%

compared with that of SiO2. Under optimized conditions for CLG such as 900℃

0.23 g·min-1 of steam flow rate and 1 of molar ratio of O/C

up to 52.75% of average concentration of H2

83.79 g·kg-1 of H2 production rate

and 1.30 m3·kg-1 of syngas production rate were achieved. The OC samples before and after reaction at 900℃ were characterized by X-ray diffraction (XRD) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The interactions within phases of Fe

K and Si

and K in presence of KFeSi3O8 phase in the OCs were observed. Twenty redox cycles testing demonstrated that the Fe4ATP6K1 oxygen carrier possessed a good cyclic stability

over 75% of both carbon conversion and cold gas efficiency

while the average concentration of each gas kept almost stable.