Reactivity and Stability of Different Red Muds as Oxygen Carriers for Chemical Looping Combustion of Methane and Biomass in a Fluidized Bed

Abstract

The reactivity and stability of two low-cost red muds (LuShan and XinFa) as oxygen carriers for chemical looping combustion (CLC) were experimentally investigated in a fluidized bed, with methane and biomass char, respectively. CH 4 conversions using the present red muds were quite low, <20% after stable cycles. The XinFa red mud had better reactivity and stability in comparison with the LuShan red mud, with its CO 2 selectivity maintained at about 80% during 50 cycles. Due to the high content of Ca in the LuShan red mud, its promoting effect on the water−gas shift reaction led to continuous high H 2 production during biomass char-fueled experiments. The XinFa red mud achieved a complete conversion of char with only CO 2 as the gaseous product. Further, it showed better resistance to attrition. The agglomeration affinity in the case of using biomass char as fuel was stronger than that when using methane as fuel. NaAlSiO 4 with a high melting point was detected in both fresh and cycled oxygen carriers. Ca 2 Al 2 SiO 7 was found in the LuShan red mud due to the interactions among Ca, Al, and Si at elevated temperatures.

Carbon Dioxide Capture and Hydrogen Production with a Chemical Looping Concept: A Review on Oxygen Carrier and Reactor

“…The chemical looping technology uses reducible oxides as OCs for chemical reactions while avoiding contact between oxidants and reductants. 27 Because utilizing a reductant of fuel favors the reduction of OC, the operating temperature of chemical looping technology is significantly lower compared to that of thermochemical processes. Chemical looping combustion (CLC) is the most extensively studied of the various chemical looping technologies.…”