LaFe1-xNix as a Robust Catalytic Oxygen Carrier for Chemical Looping Conversion of Toluene

Chemical looping biomass gasification is a novel technology converting biomass into syngas, and the selection of oxygen carrier is key for efficient tar conversion. The performance of LaFe1-xNix as a robust catalytic oxygen carrier was investigated in the chemical looping conversion of toluene (tar model compound) into syngas in a fixed bed. LaM (M = Fe, Ni, Mn, Co, and Cu) was initially compared to evaluate the effect of transition metal on toluene conversion. LaFe (partial oxidation) and LaNi (catalytic pyrolysis) exhibited better performance in promoting syngas production than other oxygen carriers. Therefore, Ni-substituted ferrite LaFe1-xNix (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) was further developed. The effects of Ni-substitution, steam/carbon ratio (S/C), and temperature on toluene conversion into C1 and H2 were evaluated. Results showed that the synergistic effect of Fe and Ni promoted toluene conversion, improving H2 yield yet with serious carbon deposition. Steam addition promoted toluene steam reforming and carbon gasification. With S/C increasing from 0.8 to 2.0, the C1 and H2 yield increased from 73.9% to 97.5% and from 197.7% to 269.6%, respectively. The elevated temperature favored toluene conversion and C1 yield. LaFe0.6Ni0.4 exhibited strong reactivity stability during toluene conversion at S/C = 1.6 and 900 °C.

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Computational Fluid Dynamics Modeling of the Fuel Reactor in NETL's 50 kWth Chemical Looping Facility

Journal of Energy Resources Technology ◽

10.1115/1.4036324 ◽

2017 ◽

Vol 139 (4) ◽

Cited By ~ 3

Author(s):

Ronald W. Breault ◽

Justin Weber ◽

Doug Straub ◽

Sam Bayham

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Oxygen Carrier ◽

Fixed Bed ◽

Nucleation And Growth ◽

Chemical Looping ◽

Gravimetric Analysis ◽

Oxygen Carriers ◽

Dynamics Modeling ◽

Fuel Reactor

The National Energy Technology Laboratory (NETL) has explored chemical looping in its 50 kWth facility using a number of oxygen carriers. In this work, the results for methane conversion in the fuel reactor with a hematite iron ore as the oxygen carrier are analyzed. The experimental results are compared to predictions using CPFD's barracuda computational fluid dynamics (CFD) code with kinetics derived from the analysis of fixed bed data. It has been found through analytical techniques from thermal gravimetric analysis data as well as the same fixed bed data that the kinetics for the methane–hematite reaction follows a nucleation and growth or Johnson–Mehl–Avrami (JMA) reaction mechanism. barracuda does not accept nucleation and growth kinetics; however, there is enough sufficient variability of the solids dependence within the software such that the nucleation and growth behavior can be mimicked. This paper presents the method to develop the pseudo-JMA kinetics for barracuda extracted from the fixed bed data and then applies these values to the fuel reactor data to compare the computational results to experimental data obtained from 50 kWth unit for validation. Finally, a fuel reactor design for near complete conversion is proposed.

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Na-β-Al2O3 stabilized Fe2O3 oxygen carriers for chemical looping water splitting: correlating structure with redox stability

10.26434/chemrxiv-2021-zgvvm-v2 ◽

2021 ◽

Author(s):

Nur Sena Yüzbasi ◽

Andac Armutlulu ◽

Thomas Huthwelker ◽

Paula Abdala ◽

Christoph Müller

Keyword(s):

Fossil Fuels ◽

Oxygen Carrier ◽

Chemical Looping ◽

Oxygen Carriers ◽

Cycle Number ◽

X Ray ◽

Transmission Electron ◽

Scanning Transmission ◽

Edx Analyses ◽

H2 Yield

Chemical looping is an emerging technology to produce high purity hydrogen from fossil fuels or biomass with the simultaneous capture of the CO2 produced at the distributed scale. This process requires the availability of stable Fe2O3-based oxygen carriers. Fe2O3-Al2O3 based oxygen carriers exhibit a decay in the H2 yield with cycle number due to the formation of FeAl2O4 that cannot be re-oxidized. In this study, the addition of sodium (via a sodium salt) in the synthesis of Fe2O3-Al2O3 oxygen carriers was assessed as a means to counteract the cyclic deactivation of the oxygen carrier. Detailed insight into the oxygen carrier’s structure was gained by combined X-ray powder diffraction (XRD), X-ray absorption spectroscopy (XAS) at the Al, Na and Fe K-edges and scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy (STEM/EDX) analyses. The addition of sodium prevented the formation of FeAl2O4 and stabilized the oxygen carrier via the formation of a layered structure, Na-β-Al2O3 phase. The resulting material, Na-β-Al2O3 stabilized Fe2O3, showed a very high H2 yield of ca. 13.3 mmol/g during 15 cycles.

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Kinetic Behavior of Fabricated CuO/ZrO2 Oxygen Carriers for Chemical Looping Oxygen Uncoupling

Processes ◽

10.3390/pr9122156 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2156

Author(s):

Young Ku ◽

Chia-Wei Chang ◽

Shr-Han Shiu ◽

Hsuan-Chih Wu ◽

Niels Michiel Moed

Keyword(s):

Elevated Temperatures ◽

Cupric Oxide ◽

Oxygen Carrier ◽

Fixed Bed ◽

Reduction Rate ◽

Fixed Bed Reactor ◽

Chemical Looping ◽

Oxygen Carriers ◽

Redox Cycles ◽

Reduction And Oxidation

Chemical looping with oxygen uncoupling (CLOU) is an innovative alternative to conventional combustion. CuO/ZrO2 oxygen carriers were tested in this system for their effectiveness and resilience. Cupric oxide (CuO) was demonstrated to be a reliable oxygen carrier for oxygen-uncoupling with consistent recyclability even after 50 redox cycles in a thermogravimetric analyzer (TGA). The reduction of CuO to generate Cu2O and oxygen was observed to be improved markedly for experiments operated at higher temperatures; however, the oxidation of Cu2O by air to generate CuO was hindered for experiments carried out at elevated temperatures. The reduction rate of fabricated CuO/ZrO2 particles containing 40% CuO was enhanced with increasing temperature and decreased with increasing particle size for experiments operated in a fixed bed reactor. The geometrical contraction and Avrami-Erofe’ev models were demonstrated to be appropriate for describing the reduction and oxidation of CuO/ZrO2, respectively. The activation energies for the reduction and oxidation were determined to be 250.6 kJ/mol and 57.6 kJ/mol, respectively, based on experimental results in the temperature range between 850 and 1000 °C.

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Effects of ZnO Addition on Fe2O3/Al2O3 Oxygen Carriers on CH4 Reduction for Chemical Looping Combustion

Materials Science Forum ◽

10.4028/www.scientific.net/msf.872.196 ◽

2016 ◽

Vol 872 ◽

pp. 196-200

Author(s):

Sujinda Thongsermsuk ◽

Benjapon Chalermsinsuwan ◽

Prapan Kuchonthara ◽

Pornpote Piumsomboon

Keyword(s):

Oxygen Carrier ◽

Synergetic Effect ◽

Fixed Bed ◽

Reduction Process ◽

Fixed Bed Reactor ◽

Chemical Looping Combustion ◽

Chemical Looping ◽

Oxygen Carriers ◽

Fuel Gas ◽

Physical Mixing

Fe2O3/Al2O3/ZnO oxygen carriers with small content ZnO (5 wt% to 10 wt%) were prepared by physical mixing method and were evaluated its capability as an oxygen carrier in a chemical looping combustion. The combustion was conducted by using CH4 as a fuel gas. The reduction process of Fe2O3/Al2O3/ZnO oxygen carrier was carried out in a fixed bed reactor. The solid reduction products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope with EDS Attachment (SEM-EDS). The results show that the reactivity of Fe2O3/Al2O3/ZnO oxygen carriers is greater than that of Fe2O3/Al2O3 which is implied the synergetic effect between ZnO and Fe2O3. XRD results show that the iron oxide in the oxygen carriers is reduced to metallic iron. SEM-EDS also shows that the iron agglomeration is prevented. Consequently, the suitable content of ZnO in oxygen carriers is ranged from 5 wt% to 10 wt%.

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Na-β-Al2O3 stabilized Fe2O3 oxygen carriers for chemical looping water splitting: correlating structure with redox stability

10.26434/chemrxiv-2021-zgvvm ◽

2021 ◽

Author(s):

Nur Sena Yüzbasi ◽

Andac Armutlulu ◽

Thomas Huthwelker ◽

Paula Abdala ◽

Christoph Müller

Keyword(s):

Fossil Fuels ◽

Oxygen Carrier ◽

Chemical Looping ◽

Oxygen Carriers ◽

Cycle Number ◽

X Ray ◽

Transmission Electron ◽

Scanning Transmission ◽

Edx Analyses ◽

H2 Yield

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Coal Chemical-Looping with Oxygen Uncoupling (CLOU) Using a Cu-Based Oxygen Carrier Derived from Natural Minerals

Energies ◽

10.3390/en12081453 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1453 ◽

Cited By ~ 2

Author(s):

Ping Wang ◽

Bret Howard ◽

Nicholas Means ◽

Dushyant Shekhawat ◽

David Berry

Keyword(s):

Solid Fuel ◽

Low Cost ◽

Oxygen Carrier ◽

Fixed Bed ◽

Xrd Analysis ◽

Reaction Rates ◽

Fixed Bed Reactor ◽

Chemical Looping ◽

Oxygen Carriers ◽

Redox Cycles

Chemical-looping with oxygen uncoupling (CLOU) is considered a promising technology to burn solid fuels with improved CO2 capture and has the potential to improve fuel conversion and reaction rates. Cu-based oxygen carriers (Cu-OC) are often used in solid fuel CLOU. This study focused on investigating Cu-OC derived from a natural mineral for solid fuel CLOU because of their potentially lower cost compared to synthetic OCs. Reactivity and recyclability of a natural ore-derived Cu-OC on coal char (Powder River Basin sub-bituminous coal) were studied at 900 °C in Ar and air using TGA-QMS and fixed-bed reactor-QMS for five cycles. Cu-OC was prepared by simply heating chalcopyrite in air. Chalcopyrite is one of the principle copper sulfide ores and one of the primary ores for copper. The prepared Cu-OC had primarily CuO and CuFe2O4 (CuOFe2O3) as active compounds based on XRD analysis and an oxygen capacity 3.3% from oxygen uncoupling. The carbon conversion efficiency Xc was 0.94 for reduction at a ratio of Cu-OC to char ϕ = 75 and the product gas was primarily CO2 with trace O2. The reactivities and the rates were similar for five redox cycles. These results indicate that the natural ore-derived material with low cost has potential as a competitive oxygen carrier in solid fuel CLOU based on its reactivity in this study.

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