Oxide Oxygen Carriers Research Articles

Particle-Scale Reduction Analysis of CuFeMnO4 with Hydrogen for Chemical Looping Combustion

In this work, CuFeMnO4 (copper iron manganese oxide) oxygen carrier was characterized using differential scanning calorimetry/thermogravimetric analysis (TGA), in situ X-ray diffraction, and scanning electron microscopy–energy dispersive X-ray spectroscopy (EDS) to gain a clear elucidation of the chemical looping combustion reactions with H2 which is a component of synthesis gas. A reaction model which best described the experimental TGA reaction data was selected from the analysis. Intrinsic rate of reaction parameters obtained from the study could be used for designing a reactor for scale-up. A model with combined contributions from nucleation and growth model and dimensional phase boundary model was found to exhibit the best correlation with the experimental data. The analysis provided validation of intrinsic reaction rates and other rate parameters.

Comparison of metallic oxide, natural ore and synthetic oxygen carrier in chemical looping combustion process

As one of clean coal combustion ways, chemical looping combustion (CLC) showed high CO2 capture efficiency with lower energy penalty. But these processes were limited by the low reaction rate between oxygen carriers (OCs) with coal char. This study evaluated the performances of Cu-based OCs with coal in in-situ gasification chemical-looping combustion (iG-CLC) and chemical-looping with oxygen uncoupling (CLOU) process. CuO modified by iron ore and chrysotile were employed as OCs which the addition of chrysolite improved the char gasification and iron ore enhanced the stability of CuO at high temperature. Results showed that CuO supported by ores (chrysolite and iron ore) had better H2 and CO conversion under H2O atmosphere than CuO and iron ore. Chrysolite decorated CuO can convert almost all H2 to H2O at 850 °C. Synthetic OCs showed better stability and high temperature tolerance during 10 redox cycles.

Mechanistic study of the CO oxidation reaction on the CuO (111) surface during chemical looping combustion

Cu-based oxides oxygen carriers and catalysts are found to exhibit attractive activity for CO oxidation, but the dispute with respect to the reaction mechanism of CO and O2 on the CuO surface still remains. This work reports the kinetic study of CO oxidation on the CuO (111) surface by considering the adsorption, reaction and desorption processes based on density functional theory calculations with dispersion correction (DFT-D). The Eley–Rideal (ER) CO oxidation mechanism was found to be more feasible than the Mars-van-Krevelen (MvK) and Langmuir–Hinshelwood (LH) mechanisms, which is quite different from previous knowledge. The energy barrier of ER, LH, and MvK mechanisms are 0.557, 0.965, and 0.999 eV respectively at 0 K. The energy barrier of CO reaction with the adsorbed O species on the surface is as low as 0.106 eV, which is much more active in reacting with CO molecules than the lattice O of CuO (111) surface (0.999 eV). A comparison with the catalytic activity of the perfect Cu2O (111) surface shows that the ER mechanism dictates both the perfect Cu2O (111) and the CuO (111) surface activity for CO oxidation. The activity of the perfect Cu2O (111) surface is higher than that of the perfect CuO (111) surface at elevated temperatures. A micro-kinetic model of CO oxidation on the perfect CuO (111) surface is established by providing the rate constants of elementary reaction steps in the Arrhenius form, which could be helpful for the modeling work of CO catalytic oxidation.

Iron oxides with gadolinium-doped cerium oxides as active supports for chemical looping hydrogen production

Supporting materials are often employed to enhance the stability of iron oxides oxygen carriers, but the reactivity is compromised for the dilution of the active phase. Here, we report several iron oxides supported by ionic conducting gadolinium-doped cerium oxides (GDC) for efficient chemical looping hydrogen production. The results show that GDC support can simultaneously improve redox stability and activity. Specifically, the produced Fe2O3/Gd0.3Ce0.7O3−δ exhibits a high hydrogen production rate of ~0.71 mmol·g−1·min−1 and hydrogen yield of ~10 mmol·g−1 with negligible decay through 20 redox cycle. When using methane as the reducing agent, Fe2O3/Gd0.3Ce0.7O3−δ shows high methane conversion of 75.67% and much lower carbon deposition than Fe2O3. The high performance is attributed to the improved oxide ion-conductivity through the oxygen carrier, which is further verified as the ability of the GDC support to accelerate the oxygen diffusion in the bulk. The explored support effects in this work can be extended to design oxygen carrier materials with both high activity and stability.

Design and Operations of a 15 kWth Subpilot Unit for the Methane-to-Syngas Chemical Looping Process with CO2 Utilization

The methane-to-syngas (MTS) chemical looping process is an advanced methane reforming technology for the production of high purity syngas. The developed MTS process utilizes metal oxide oxygen carriers in a cocurrent moving bed reactor to partially oxidize the methane such that the resulting syngas stream is undiluted by nitrogen in air or H2 from overconversion and directly suitable for downstream processing. The oxygen carriers are regenerated with air in a separate fluidized bed reactor producing a spent air stream separate from the product syngas, circumventing the need for cryogenic air separation units. In this work, a 15 kWth subpilot unit is designed and operated in a continuous manner to experimentally confirm the viability of the MTS process. Reactor design considerations and methodology are discussed in detail. An iron–titanium composite oxygen carrier is used as the oxygen carrier for its ability to achieve high methane conversion while regulating the product syngas to the partial oxidation products, CO and H2. Syngas is produced with an H2/CO ratio of ∼2, and a purity of ∼97% is produced with methane conversion exceeding 99%. The coinjection of methane with H2 and/or H2O is explored for the purpose of H2 utilization and flexible H2/CO ratios, allowing the MTS process to produce syngas for a variety of downstream processes without reactor modification. The results indicate that syngas with H2/CO ratios ranging from 1.19 to 2.50 with high methane conversion and syngas purity can be produced with coinjection. No evidence of carbon deposition on the oxygen carrier is revealed, and the oxygen carrier retained structural integrity after subjection to reaction and circulation in the subpilot unit.

Oxygen Transfer Capacity of Pseudobrookite Particles Derived from Ilmenite Mineral (x wt.%CuO/y wt.%red Mud-z wt.%ilmenite).

The minerals have a somewhat slower than other transition metals at critical reduction rates in their ability to deliver oxygen. Thus, single minerals alone do not exhibit a higher oxygen transfer capacity than metal oxide oxygen carriers. In this study, we try to solve the problem of single mineral ilmenite (FeTiO₃) by combining it with Fe-based red mud and Cu oxide. When the ilmenite was used without calcination, the CH₄-CO/air redox cycle showed rapid decayed. However, when ilmenite was calcined, the CH4-CO/air redox cycle became stable, and the oxygen transfer rate increased to 4.2%. This is because the FeTiO₃ structure was converted to the pseudobrookite (Fe₂TiO5) structure through the calcination process. That is, the Fe2+ ion in the ilmenite structure was converted into an Fe3+ ion. When 30 wt.% of red mud was added to the Fe ion, it reacted with the rutile-type titania mixed with pseudobrookite-typed Fe₂TiO5, producing an almost perfect pseudobrookite crystal. This resulted in a slight increase in the capacity of oxygen transfer to 4.9%. When 15 wt.% of Cu oxide was added, the oxygen transfer capacity increased to 6.0%. This performance was indicated by the cyclic voltammetry curve that remained constant even after 200 cycles. Here, we argue that if low-cost minerals as a base material are used in appropriate amounts, the production of a lowest-cost oxygen carrier can be achieved.

Removing NOx, CO and HC from automobile exhaust based on chemical looping combustion

AbstractBackgroundTo meet more stringent automobile exhaust emission standards without using platinum group metal three‐way catalysts (TWCs), two nonprecious metal oxide oxygen carriers, Cu10/Al90 and Ni10/Al90, were investigated for the simultaneous and thorough removal of nitrogen oxides (NOx), carbon monoxide (CO) and hydrocarbons (HC) from automobile exhaust.ResultsIn oxidation reactions of the reductive oxygen carriers with NO, the reductive oxygen carriers were converted to the oxidative oxygen carriers and NO was simultaneously reduced to N2. Then, the oxidative oxygen carriers were regenerated to the reductive oxygen carriers with reducing gases, including CO, H2 and HC. At the same time, CO was converted to CO2, H2 was converted to H2O, and HC was converted to CO2 and H2O. The simultaneous removal of NOx, CO and HC could be achieved based on a chemical looping combustion mechanism. Compared with Ni10/Al90, Cu10/Al90 exhibited better performance for removing NO, CO and C3H6 from simulated automobile exhaust. However, the reductive Ni10/Al90 had an excellent steam reforming catalytic activity and was capable of converting residual C3H6 in the exhaust to harmless H2 and CO2.ConclusionBased on these findings, a novel chemical looping combustion process is proposed, in which the first oxygen carrier‐filling layer based on Cu10/Al90 removed NOx, CO and HC simultaneously, and the second oxygen carrier‐filling layer based on Ni10/Al90 removed residual NO and C3H6. © 2019 Society of Chemical Industry

Cobalt doping modification for enhanced methane conversion at low temperature in chemical looping reforming systems

Abstract Chemical looping reforming (CLR) is a promising strategy of methane conversion to syngas with low cost and minimal environmental impact. A major challenge for chemical looping reforming systems is the development of oxygen carriers that have high reactivity, high oxygen carrying capacity, and long-term durability. We demonstrate that the addition of a low concentration of cobalt dopant to iron-based oxygen carriers can dramatically enhance the reactivity in CLR processes at low temperatures while maintaining the recyclability. The methane conversion increased by around 300% for Co-doped iron oxide compared to pure iron oxide oxygen carriers from 600 °C to 800 °C. It was found that 2% Co dopant concentration is optimal for methane conversion rate and cost of oxygen carriers at different temperatures. Density functional theory (DFT) calculations reveal that the Co dopant has a short-range effect on the formation of oxygen vacancies. The Co-doping-induced oxygen vacancy significantly reduces energy barriers of CH4 reforming on the surface of iron oxide oxygen carriers, leading to the reactivity enhancement. Our findings provide a pathway to lower the methane reforming temperature in chemical looping systems, while improving the syngas yield with desired oxygen carrier recyclability.

Improved iron oxide oxygen carriers for chemical looping hydrogen generation using colloidal crystal templated method

Abstract Iron oxide has been widely studied in chemical looping hydrogen generation (CLHG) process as an oxygen carrier, but fast decline of its activity in redox cycles due to sintering and agglomeration is one of the main drawbacks. In this work, the colloidal crystal templated (CCT) method was applied to synthesize Fe2O3/CeO2 oxygen carrier and the mole ratio of Fe/Ce was 8:2, aiming to inhibit adjacent grains from agglomerating and improve the contact between the fuel gas and the oxygen carrier. The redox performances were evaluated with CO as fuel in a batch fixed bed reactor for 20 redox cycles, with oxygen carriers prepared by co-precipitation (CP) and sol-gel (SG) methods as references. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and H2-temperature programmed reduction (H2-TPR) were used for characterization. The results showed that the calcination temperature lower than 750 °C was suitable for the CCT. The redox experiments showed that the H2 yield and the redox stability for the oxygen carrier prepared by CCT were higher than those by co-precipitation and sol-gel methods. The H2 yield of CCT oxygen carrier kept stable from the 3rd cycle and was 8.5 mmol/gOC in the 20th cycle. The pore structures resulting from CCT were different from another two oxygen carriers before and after the cycles, but maintained well through SEM images, leading to high activity and stability during redox cycles. The crystallite sizes of Fe2O3 and CeO2 before and after redox cycles were the smallest for the CCT oxygen carrier from XRD patterns. In addition, H2-TPR demonstrated that CCT oxygen carrier exhibited the highest reactivity.

Chemical looping with oxygen uncoupling: an advanced biomass combustion technology to avoid CO2 emissions

Bioenergy with carbon dioxide (CO2) capture and storage (BECCS) technologies represent an interesting option to reach negative carbon emissions, which implies the removal of CO2 already emitted to the atmosphere. Chemical looping combustion (CLC) with biomass can be considered as a promising BECCS technology since CLC has low cost and energy penalty. In CLC, the oxygen needed for combustion is supplied by a solid oxygen carrier circulating between the fuel and air reactors. In the fuel reactor, the fuel is oxidized producing a CO2-concentrated stream while the oxygen carrier is reduced. In the air reactor, the oxygen carrier is regenerated with air. Chemical looping with oxygen uncoupling (CLOU) is a CLC technology that allows the combustion of solid fuels as in common combustion with air by means of an oxygen carrier that release gaseous oxygen in the fuel reactor. In the last years, several Cu-based, Mn-based, and mixed oxide oxygen (O2) carriers have been tested showing good CLOU properties. Among them, copper (Cu)-based and Cu-Manganese (Mn) mixed oxides showed high reactivity, O2 release rate, and high O2 equilibrium concentration. The aim of this work is to study the viability of biomass combustion by CLOU process. The combustion of three types of biomass (pine sawdust, olive stone, and almond shell) were studied in a continuous 1.5 kWth CLC unit. Two O2 carriers were tested: a Cu-based oxygen carrier with Magnesium, Aluminum, Oxgen (MgAl2O4) as an inert prepared by spray drying (Cu60MgAl) and a mixed Cu-Mn oxide prepared by spray granulation (Cu34Mn66). These materials are capable of releasing gaseous oxygen when they are reduced in a different range of temperatures. CO2 capture and combustion efficiency were evaluated. Two fuel reactor operation temperatures were used: 775–850 °C for Cu34Mn66 and 900–935 °C for Cu60MgAl. High CO2 capture efficiencies and 100% combustion efficiency were reached with both oxygen carriers and with all the biomasses tested. Therefore, the CLOU technology with the Cu- and Cu-Mn-based oxygen carriers allowed avoiding CO2 emissions maintaining high combustion efficiencies. Results obtained demonstrate that this innovative biomass combustion technology combined with carbon storage lets an efficient BECCS process implementation.

Reactivity improvement of ilmenite by calcium nitrate melt infiltration for Chemical Looping Combustion of biomass

Chemical Looping Combustion is a novel process that generates sequestration-ready CO2 from the combustion of woody biomass without requiring a gas separation step and without diluting the CO2 with N2 from air. This is achieved by oxidizing the fuel with lattice oxygen of a metal oxide oxygen carrier. When using cheap and abundant ilmenite ore (FeTiO3) as the oxygen carrier, the rather low reactivity towards volatiles released from the biomass upon devolatilization, as well as detrimental structural changes due to a segregation of Fe and Ti in the material, are of concern. These issues can be addressed by modifying ilmenite with Ca via melt infiltration. In this work, we demonstrate that this modification results in a good distribution of Ca throughout the ilmenite particles that a) prevents detrimental Fe/Ti segregation, b) improves the mechanical stability of the particle compared to materials prepared by solution impregnation and c) improves the reactivity of this material towards hydrogen and wet methane. Moreover, fixed bed experiments showed that the Ca modification not only resulted in increased methane conversion, but also in an increased degree of oxidation of gaseous intermediates CO and H2. We thus conclude that the performance of ilmenite in Chemical Looping processes can be significantly enhanced by Ca modification of ilmenite either prior to use or in-situ during operation of this bed material with Ca-rich fuels such as woody biomass.

Oxygen Vacancy Creation Energy in Mn-Containing Perovskites: An Effective Indicator for Chemical Looping with Oxygen Uncoupling

Chemical looping with oxygen uncoupling (CLOU) is a novel process for carbon dioxide capture from coal combustion. Designing a metal oxide oxygen carrier with suitable oxygen release and uptake (re...

Phase interactions in Ni-Cu-Al2O3 mixed oxide oxygen carriers for chemical looping applications

Chemical looping processes present great potentials to achieve carbon capture and fuel conversion with high thermodynamic efficiencies. Well-known applications of chemical looping include combustion and methane reforming, where phase interactions in oxygen carriers play important roles in determining the process performance. In this study, we systematically investigate the interactions between various phases in Ni-Cu-Al2O3 mixed oxides oxygen carriers, which were prepared from layered double hydroxides precursors, synthesized hydrothermally using urea and metal nitrates. It appears that the addition of 32–45 wt% Al2O3 was sufficient to prevent sintering effects over 100 redox cycles at 800 °C, 1 atm, using methane as the fuel. The oxide phases and their compositions were determined using a set of complementary analytical techniques, allowing us to establish relationships between (i) the compositions of the mixed oxides, (ii) the chemical activity of the various types of lattice oxygen present and (iii) the distributions of gaseous products of chemical looping methane oxidation. We found that the mutual doping between NiO and CuO leads to enhanced lattice oxygen activities, whilst the solid solution of NiAl2O4 and CuAl2O4 leads to reduced lattice oxygen activity in the spinel phase, which also turns out to be particularly resistant to carbon deposition. The generality of the composition – activity - performance relationship is demonstrated by the successful prediction of the product distributions of methane oxidation based on solely the elemental compositions of the oxygen carriers. These findings enable the rational formulation of Ni-Cu-Al2O3 oxygen carriers for methane conversion with precise control of product selectivity.

Denitration of the gas-fired boiler flue gas based on chemical-looping combustion

The denitration performances of transition metal oxide oxygen carriers (OCs) including CuO/Al2O3, MnO2/Al2O3 and NiO/Al2O3 for the gas-fired boiler flue gas were investigated. The results showed that NO was able to be reduced to N2 through a direct reaction with the reduced OCs, and at the same time, the reduced OCs were converted to the oxidized OCs. Then, the oxidized OCs were able to be regenerated to the reduced OCs by introducing reducing gases. As such, the continuous denitration was achieved based on a chemical-looping combustion (CLC) denitration mechanism. Among the reduced CuO/Al2O3, MnO2/Al2O3 and NiO/Al2O3, the reduced CuO/Al2O3 showed the best denitration activity. The NO denitration based on the reduced CuO/Al2O3 and CO also included the catalytic mechanism, whereas the CLC mechanism was dominant. The denitration performance of CO as a reducing gas was significantly better than that of C2H5OH, CH3OH, H2 or NH3. 8% CO2 in the flue gas inhibited the denitration below 250 °C, whereas 15% H2O in the flue gas improved the denitration above 125 °C. O2 in the flue gas deteriorated the denitration through reducing the proportion of the reduced species in the OC, whereas a high NO conversion could be obtained through increasing CO concentration to make λ less than 1.0. For the denitration of a simulating flue gas based on the reduced CuO/Al2O3 and CO, the temperature needed for a NO conversion of 90% was as low as 125 °C at 10,000 h−1.

High purity syngas and hydrogen coproduction using copper-iron oxygen carriers in chemical looping reforming process

Chemical looping reforming presents an attractive alternative to the conventional processes for chemicals and energy production from carbonaceous fuels with significant reduction in carbon emissions and high exergy efficiency. Production of syngas and hydrogen is important because the former is a critical building block for valuable chemicals and latter is a source of clean energy. The use of copper-iron (Cu-Fe) oxygen carriers for coproducing syngas and hydrogen in a chemical looping reforming process is studied via experiments and process simulations. Three different compositions of Cu and Fe oxides are examined for their properties concerning the reactivity towards fuel and the selectivity towards syngas. The feasibility of using a co-current moving bed reactor configuration for syngas production is probed experimentally in a fixed bed reactor by placing the fully oxidized and reduced oxygen carrier in series. The methane conversion and dry syngas purity as high as 99.5% and 97.5%, respectively, are observed for copper oxide (20 wt%) - iron oxide (60 wt%) - aluminium oxide (20 wt%) oxygen carrier in a simulated co-current moving bed reactor. Key performance parameters including effective thermal efficiency for 5 different configurations of the chemical looping reforming process from ASPEN Plus simulation software are compared against the baseline case of the auto-thermal reforming process. Apart from an improvement in the natural gas conversion and syngas purity in the chemical looping reforming process, the net hydrogen production is increased by 28% and effective thermal efficiency is increased by 10% over that of the auto-thermal reforming process.

Syngas Production from Chemical‐Looping Reforming of Methane Using Iron‐Doped Cerium Oxides

AbstractA series of iron‐doped cerium oxide oxygen carriers CexFe10−xOδ (x=9, 7, 5) were prepared by citric acid sol‐gel method and characterized by X‐ray powder diffraction (XRD), Brunauer Emmett Teller (BET), Temperature‐Programmed Reduction, and Oxidation (H2‐TPR/O2‐TPO). The reaction activity and cycle stability of oxygen carriers with methane at 850 °C were investigated in a fixed bed reactor and the capacity of oxygen storage was studied by a chemical adsorption instrument. Results showed that methane conversion and oxygen storage capacity of oxygen carriers were improved significantly because of the doping iron oxide. For thermostatic cycle, Ce7Fe3Oδ showed considerable durability. A three stages isothermal reaction mechanism was proposed.

New Insight into the Development of Oxygen Carrier Materials for Chemical Looping Systems

Abstract Chemical looping combustion (CLC) and chemical looping reforming (CLR) are innovative technologies for clean and efficient hydrocarbon conversion into power, fuels, and chemicals through cyclic redox reactions. Metal oxide materials play an essential role in the chemical looping redox processes. During reduction, the oxygen carriers donate the required amount of oxygen ions for hydrocarbon conversion and product synthesis. In the oxidation step, the depleted metal oxide oxygen carriers are replenished with molecular oxygen from the air while heat is released. In recent years, there have been significant advances in oxygen carrier materials for various chemical looping applications. Among these metal oxide materials, iron-based oxygen carriers are attractive due to their high oxygen-carrying capacity, cost benefits, and versatility in applications for chemical looping reactions. Their reactivity can also be enhanced via structural design and modification. This review discusses recent advances in the development of oxygen carrier materials and the mechanisms of hydrocarbon conversion over these materials. These advances will facilitate the development of oxygen carrier materials for more efficient chemical looping technology applications.

Side Reactions of Coal Tar Pyrolysis Products with Different Reduction States of Iron-Based Oxygen Carriers

To evaluate the effects of severe side reactions on the product yield of pyrolysis of coal tar with iron oxide oxygen carriers (OCs), simulation experiments were carried out and analyzed by thermogravimetry–mass spectrometry. The reactions occurred between iron-based OCs with different reduction states and carbon black (CB) and syngas products. The H2 present in syngas showed the lowest initial reaction temperature and the highest decrease in concentration, indicating its strong reactivity. Because CO reacted with iron-based OCs at a higher temperature and had a slow reaction rate, the relative reactivity at the low-temperature stage is lower compared to H2. At the high-temperature stage, the reaction of CO was inhibited by CH4 and the concentration of CO was affected by the reactions of CB. CH4 had the highest initial reaction temperature and least consumption but a higher reaction rate than CO in its narrow temperature range. Therefore, CH4 clearly affected the side reactions at high temperatures. Scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis of the solid residues shows that the consumption of CB is low and the Fe/O ratio in the solid residues is larger, owing to the higher relative reactivity of syngas with different reduction states of iron-based OCs.

Coal combustion with a spray granulated Cu-Mn mixed oxide for the Chemical Looping with Oxygen Uncoupling (CLOU) process

The Chemical Looping with Oxygen Uncoupling (CLOU) process is a form of Chemical Looping Combustion (CLC) technology that enables the combustion of solid fuels by means of oxygen carriers that release gaseous oxygen in the fuel reactor, i.e. with oxygen uncoupling capability. In recent years, tests have found several Cu-based, Mn-based and mixed oxide oxygen carriers with suitable properties for the CLOU process. Among them, Cu-Mn mixed oxides show high reactivity and high O2 equilibrium concentration at temperatures of interest for coal combustion. In this work, proof of concept was demonstrated by burning coal with Cu-Mn mixed oxides in a 1.5kWth CLOU unit for the first time. The effect of fuel reactor temperature, solids circulation flow, fluidization agent in the fuel reactor (inert N2 or steam as gasifying agent), and excess air in the air reactor on combustion efficiency and CO2 capture rate was analysed. The results showed that high combustion efficiency and CO2 capture are feasible using this material at relatively low fuel reactor operating temperatures. Therefore, the developed Cu-Mn mixed oxide was a suitable material for use as an oxygen carrier for the CLOU combustion of solid fuels. Optimum operating conditions were determined for this oxygen carrier with regard to the oxygen circulation rate and air reactor conditions for the regeneration of the oxygen carrier.

Thermodynamic modeling of the combined CLG–CLHG system for syngas and hydrogen generation

The combined CLG and CLHG is a novel technology for the co‐generation of syngas and H2‐riched gas. In CLG process, the reduction of oxygen carrier with biomass can produce syngas. In CLHG process, the oxidation of oxygen carrier with steam can produce H2‐riched gas. In this study, the Ce‐based oxygen carrier was selected as the candidate material based on the Gibbs free energy changes (ΔG) of the splitting water reactions. The redox mechanism of the Ce‐based oxygen carrier was discussed and thermodynamic analysis of syngas and hydrogen generation was performed by Gibbs free energy minimization method. The optimal O/C in the GR was determined as 0.6–0.8 and the total dry concentration of CO and H2 was higher than 95.0% under 850–1000°C. The optimal S/C in the SR was determined as 2–3 and the H2 fraction was higher than 70.0% under 850–1000°C. In the AR, all of the Ce oxides can be regenerated to CeO2 in the air flow of 0.5 kmol at 700°C. After one CLG–CLHG cycle, there was no carbon deposition on the surface of oxygen carrier. The redox mechanism of the Ce‐based oxygen carrier was defined as: © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1132–1139, 2018