Abstract:
Adsorbent-decorated Fe
2O
3/Al
2O
3 as oxygen carrier (OC) was proposed for restraining the emission of chloride, sulfide and heavy metals during the chemical-looping combustion process of gaseous or solid fuels. Three adsorbents (K
2O, Na
2O and CaO) were selected for decorating these OC particles. First, the raw Fe
2O
3/Al
2O
3 and three adsorbent-decorated Fe
2O
3/Al
2O
3 were reduced by synthesis gas and then the oxidation kinetics of four reduced OCs (raw FeO/Al
2O
3 and three adsorbent-decorated FeO/Al
2O
3) were investigated by using thermogravimetric analysis (TGA) technique in air atmosphere at four temperatures (850, 875, 900 and 925℃). It was found that the translation of FeO to Fe
2O
3 can be described by the phase boundary-controlled (contracting cylinder) model, and the apparent activation energy (
E) was calculated to be 13.71, 20.21, 21.62 and 24.20 kJ/mol for raw FeO/Al
2O
3, K
2O-decorated FeO/Al
2O
3, Na
2O-decorated FeO/Al
2O
3 and CaO-decorated FeO/Al
2O
3, respectively. Last, the reaction mechanism was evaluated through comparing the calculated data from the obtained kinetic parameters and the experimental results, which demonstrated the reliability of the phase boundary-controlled (contracting cylinder) model.