Evaluation of Iron-based Oxygen Carrier Supported on Alumina/Titania for Charcoal Combustion through Chemical Looping Process

Abstract

Hematite supported on alumina or alumina/titania was fabricated to serve as an oxygen carrier in the chemical looping combustion (CLC) of charcoal. The reduction rate of Fe 2 O 3 /Al 2 O 3 and Fe 2 O 3 /Al 2 O 3 /TiO 2 particles increased with the reactor inlet's CO concentration and displayed a slight effect from elevated operating temperatures. Applying the shrinking core model, the mass transfer coefficients (k g ) for the reduction of Fe 2 O 3 /Al 2 O 3 and Fe 2 O 3 /Al 2 O 3 /TiO 2 by CO were found to be 0.16 and 0.22 mm s -1 , respectively, and using the Fe 2 O 3 /Al 2 O 3 and Fe 2 O 3 /Al 2 O 3 /TiO 2 to combust charcoal resulted in carbon conversion rates of approximately 61.8% and 47.2%, respectively, when the inlet steam flow rate was set to 221.4 mmol min -1 . Significantly, a higher inlet steam flow rate may not be advantageous when employing iron-based oxygen carriers. More heat was released during combustion with the Fe 2 O 3 /Al 2 O 3 than with the Fe 2 O 3 /Al 2 O 3 /TiO 2 due to a high flow rate for the former being used. When Fe 2 O 3 /Al 2 O 3 /TiO 2 was used as the oxygen carrier, the particles, which contained a large percentage of Fe 2 O 3 , exhibited high reactivity to syngas (CO/H 2 ); thus, less Fe 2 O 3 /Al 2 O 3 /TiO 2 than Fe 2 O 3 /Al 2 O 3 was required to combust the charcoal.

Chemical Looping Combustion of Isopropanol in Aqueous Solution with Fabricated Fe2O3/Al2O3 and Fe2O3/Al2O3/TiO2 Oxygen Carriers

“…The kinetics for the reduction Fe2O3/Al2O3 and Fe2O3/Al2O3/TiO2 by hydrogen were calculated with the shrinking core model (SCM), exercised by most researchers for the application of various oxygen carriers for chemical looping (Abad et al, 2007;Cabello et al, 2014;Abad et al, 2015;Wu and Ku, 2018;Wu and Ku, 2019), as described in Eqs. ( 13) to ( 18…”

Effect of the Conversion Degree on the Apparent Kinetics of Iron-Based Oxygen Carriers

“…Abad et al reported the reduction kinetics toward syngas of three synthetic oxygen carriers; of them, one was an iron-based material. Some studies reported the kinetics of supported iron-based oxygen carriers for chemical looping application, either in a fixed bed system , or TGA. − Mendiara et al . examined the redox kinetics of an iron ore using TGA.…”