(103a) Coal Chemical Looping Combustion Using Bimetallic Cu-Fe Oxygen Carrier in a Carbon Dioxide Gas Environment

Chemical-looping
combustion (CLC) is mainly proposed for a circulating fluidized bed (CFB) using
various fluidizing gases such as carbon dioxide (CO₂) or steam (H₂O).
CO₂ in the CLC is also a reactant and the process may be considered
as CO₂ utilization.  Prior
studies showed that bimetallic Cu-Fe oxygen carriers (OC) had higher
reactivities compared to monometallic iron oxide.  In this study, the
Cu-Fe OCs with an inert support silicon dioxide (SiO₂) or zirconium
dioxide (ZrO₂) were synthesized using high pressure pelletization followed by calcination at 950 or 1100^oC.
Reactivities of the OCs with coal char and their CO₂ conversion
efficiency were investigated at 950 and 1050^oC in multiple-cycle tests
under a CO₂ gas environment. The OCs with a ZrO₂ support can
be tested at a higher temperature than those with an SiO₂ support due
to problems associated with sintering of SiO₂-supported OCs when calcined
at 1100˚C. Results show high carbon conversions, carbon conversion rates, CO₂
conversion efficiencies and cyclabilities of the combined Cu-Fe OCs with the
char under CO₂.