CO2 conversion to CO by auto-thermal catalyst-assisted chemical looping. (December 2016)

• Record Type: Journal Article
• Authors: Hu, Jiawei; Buelens, Lukas; Theofanidis, Stavros-Alexandros; Galvita, Vladimir V.; Poelman, Hilde; Marin, Guy B.
• Is Part Of: Journal of CO₂ utilization. Volume 16(2016)
• Page Start: 8
• Page End: 16
• Publication Date: 2016-12
• Subjects: CO2 utilization -- CO production -- Ni-Fe catalyst -- Iron oxide -- Oxygen storage material; Carbon dioxide -- Periodicals; Carbon dioxide -- Environmental aspects -- Periodicals; Carbon dioxide mitigation -- Periodicals; Carbon dioxide; Carbon dioxide -- Environmental aspects; Carbon dioxide mitigation; Periodicals; 628.53205
• DOI: 10.1016/j.jcou.2016.05.006
• Languages: English
• ISSNs: 2212-9820

Abstract

Graphical abstract: Abstract: A bifunctional 9 wt.%NiO-16 wt.%Fe2 O3 /MgAl2 O4 material was prepared for CO2 conversion to CO by auto-thermal catalyst-assisted chemical looping. This process is designed to maximize CO2 conversion. The generation of CO from CO2 was investigated between 873 K and 1023 K. The high endothermicity of methane dry reforming and the material deactivation by coke deposition were avoided by the simultaneous feeding of CH4, CO2 and O2 in a 1:1:0.5 molar ratio during the reduction half-cycle of chemical looping. In this half-cycle, interaction of Ni with Fe leads to Ni-Fe alloy formation. The resulting Ni-based catalyst converts CH4 + CO2 + O2 into a mixture of CO and H2, which both reduce Fe3 O4, producing CO2 and H2 O. In the CO2 re-oxidation half-cycle, CO is produced and the Ni-Fe alloy decomposes into Ni and Fe3 O4 . The reduction capacity ( R c ) of the gas mixture strongly depends on the ratio R c between reducing and oxidizing gases. Based on thermodynamic calculations, high conversion of Fe3 O4 to reduced state can be reached if R c > 2 and T > 873 K. During prolonged auto-thermal chemical looping at 1023 K, the 9 wt.%NiO–16 wt.%Fe2 O3 /MgAl2 O4 suffers from deactivation in the first five cycles, after which a more stable operation is established. Based on TEM measurements, sintering was found to be the main cause for the initial decrease of CO production.