Understanding of the oxygen uncoupling characteristics of Cu–Fe composite oxygen carriers for chemical-looping gasification

Kun Wang (Corresponding author), Fuqing Wang, Qingbo Yu (Corresponding author), Martin van Sint Annaland, Ziyu Wang, Jiaze Xi, Yunwei Zhang, Meng Xue, Shijie Du

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

A Cu–Fe oxygen carrier (OC) with oxygen uncoupling capability is proposed to be applied in chemical-looping gasification with oxygen uncoupling (CLGOU) technology to increase the gasification rate. Density functional theory analysis shows that a chemical reaction occurs after Cu4O4 cluster adsorption onto α - Fe2O3 (001) surface. Extension of bond length and transfer of charge indicate the composite oxide has been activated. An optimal molar ratio of 2:1 of CuO to Fe2O3 is determined for the preparation the OC and the oxygen transport capacity is determined at 3.65 wt% with a starting oxygen uncoupling temperature is 749.5 °C. The composite OC exhibits good low-temperature oxygen uncoupling characteristics. This OC exhibits stable behaviour and satisfactory oxygen recyclability over 15 consecutive redox cycles at 900 °C / 700 °C oxygen uncoupling and absorbing temperatures. The high stability is corresponding to the calculation result (high adsorption energy of CuO onto Fe2O3). And oxygen uncoupling rates are much higher than the lower limit (0.4 wt%/min) for cracking. The chemical phases and surface micromorphology all retain stable after cycles. Using combined Coats-Redfern and Malek method, the oxygen uncoupling kinetic model of Cu–Fe OC is determined as a shrinking core model (m = 3).

Original languageEnglish
Article number106844
Number of pages11
JournalFuel Processing Technology
Volume218
DOIs
Publication statusPublished - Jul 2021

Bibliographical note

Funding Information:
This research was financially supported by National Natural Science Foundation of China ( 51604078 ); Fundamental Research Funds for the Central Universities ( N182504011 ).

Publisher Copyright:
© 2021 Elsevier B.V.

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Characteristic
  • Chemical-looping gasification
  • Composite oxygen carrier
  • Kinetics
  • Oxygen uncoupling
  • Stability

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