Preparation and Characterization of Lanthanum-Promoted Copper-based Oxygen Carriers for Chemical Looping Combustion Process

Received: May 29, 2013
Revised: December 31, 2013
Accepted: December 31, 2013
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2013.05.0175  

Cite this article:
Cao, Y., Sit, S.P. and Pan, W.P. (2014). Preparation and Characterization of Lanthanum-Promoted Copper-based Oxygen Carriers for Chemical Looping Combustion Process. Aerosol Air Qual. Res. 14: 572-584. https://doi.org/10.4209/aaqr.2013.05.0175

ABSTRACT

Chemical looping combustion (CLC) is an oxygen combustion process that results in the higher CO₂ concentrations in flue gases. Copper-based oxygen carriers have high reactivity, resulting in high purity CO₂ generation, but face the challenges of low copper melting point and potential thermal sintering under high-temperature cyclic operation. A temperature-programmed reduction and oxidation (TPR-TPO) technique (Redox) was used to simulate of the cyclic operation of copper-based oxygen carriers in the CLC process. Multiple material characterization methods were applied to the fresh and used oxygen carriers, including the determination of pore structure and surface area by Brunauer-Emmett-Telle (BET), crystal structure by X-ray diffraction (XRD) and surface phase diagram analysis by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDX). Thermally stable copper-based oxygen carriers have been successfully prepared using commercially-available Al₂O₃ as the supporting material and selected additives. A substantial resistance to agglomeration and durability in over 50 cyclic Redox tests under high temperature conditions (oxidation at 800°C and reduction at 800°C) has been confirmed for the Sample labeled as CLCA. The oxygen transfer capability was almost stable, and the CuO content ranged from 20 wt% to 23 wt% for the CLCA sample. The supporting material (Al₂O₃) significantly impacted the oxygen releasing performance and thermal stability of the copper-based oxygen carriers, due to the formation of a new crystal phase (CuAl₂O₄) which cross-links the CuO and the γ-Al₂O₃. Lanthanum accelerated the cross-linking between CuO and Al₂O₃.

Keywords: Chemical looping combustion; Oxygen carriers; Copper; Additives