Date: 18 Aug 2012

Development of Binder-Supported CaSO4 Oxygen Carriers for Chemical Looping Combustion of Methane

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Abstract

Chemical-looping combustion (CLC) has been recognized as an energy-efficient method for CO2 capture. From thermodynamics point of view, CaSO4 has a good availability in the cycle of CLC system. The inhibition of the poor mechanical strength and reactivity is fatal to a CLC system based on calcium sulfate (CaSO4). In this study, three important parameters (binder, acetic acid, and water) were selected as factors of the L9 orthogonal experiment designed to investigate the performance of the binder-supported CaSO4 oxygen carriers by intuitive analysis. Then, the suitable oxygen carriers were comprehensively studied in a fixed bed reactor. The orthogonal experiment results showed that adding binder enhanced the mechanical strength and increased the conversion of the binder-supported CaSO4, and the optimal extrusion condition was: 30 g CaSO4, 12 g SB powder (sticky pseudo-boehmite), 2.5 ml acetic acid, and 15 ml water. The results of reduction reactivity showed the conversion and mass-based reaction rates of the binder-supported CaSO4 were obviously enhanced. Moreover, the favorable performance of the binder-supported CaSO4 was explained by formation of CaAl2O4. This compound was excellent thermal stability and provided a stable nanosized framework between the crystal grains observed by field emission scanning electron microscope.