Unveiling the pivotal role of Ni doping in ilmenite as oxygen carrier to realize simultaneous enhanced oxygen release and inhibited phase segregation in chemical looping process

Evaluation of dust and gas explosion potential in chemical looping processes

The impact of alkali and alkaline earth metals on green ammonia synthesis

NiFe2O4 oxygen carrier (OC) presents higher oxygen carrying capacity than single metal oxides (NiO and Fe2O3). However, the redox ability of NiFe2O4 gets deactivated due to phase segregation. Herein, the investigation of the effect of supports (CeO2, CeZrO2, and ZrO2) on the phase stability and the redox performance of NiFe2O4 during the chemical looping (CL) process are presented. The structure of NiFe2O4‐based OCs is characterized using different characterization methods. The CL reaction is conducted in a fixed‐bed reactor at 900 °C under alternate 5% CO/N2 and 5% O2/N2 atmospheres. The results indicate that the redox performance and the phase stability of NiFe2O4‐based OCs are significantly affected by the supports. According to experimental results, CeO2 can improve the oxygen mobility of NiFe2O4. The CeO2–NiFe2O4 OC has the best performance in terms of both recyclability and phase stability during the redox cycles. The results show that CeO2–NiFe2O4 can reduce the tendency of Fe segregation due to the high concentration of oxygen vacancies. It can be reduced and reoxidized to the original crystalline phase of NiFe2O4. Nevertheless, the CeZrO2–NiFe2O4 and ZrO2–NiFe2O4 OCs have drawbacks related to serious sintering and phase segregation into Fe2O3.

Modulation of Fe-based oxygen carriers by low concentration doping of Cu in chemical looping process: Reactivity and mechanism based on experiments combined with DFT calculations

Hydrogen production from vegetable oil via a chemical looping process with hematite oxygen carriers

Chemical Looping for Energy Technology: A Special Issue

An overview of solar decarbonization processes, reacting oxide materials, and thermochemical reactors for hydrogen and syngas production

Kinetics of redox reactions of CuO@TiO2–Al2O3 for chemical looping combustion and chemical looping with oxygen uncoupling

Research progress of oxygen carriers for the chemical looping process of different feedstocks

Cu-based oxygen carriers for chemical looping processes: Opportunities and challenges

ZhunDong coal is the largest coal resource in China but is characterized by high sodium and chlorine content. Chemical looping combustion with hematite as oxygen carrier is an attractive alternative technology for ZhunDong coal conversion without severe slagging and fouling problems. However, the influence of the chemical looping process for the migration characteristics of sodium and chlorine is not clear. Especially with the presence of hematite, it is bound to have a great influence on the migration of sodium and chlorine. For better controlling slagging and fouling problems caused by sodium and chlorine migration, it is necessary to study the migration paths of sodium and chlorine in the chemical looping process. Experimental results and analysis show that the migration characteristics and path of sodium and chlorine in the chemical looping process are different at different temperature ranges. However, some common grounds could be found. The releasing form of chlorine in the chemical looping process ...

Chemical looping processes offer a compelling way for effective and viable carbonaceous fuel conversion into clean energy carriers. The uniqueness of chemical looping processes includes their capability of low cost in situ carbon capture, high efficiency energy conversion scheme, and advanced compatibility with state-of-the-art technologies. Based on the different functions of looping particles, two types of chemical looping technologies and associated processes have been developed. Type I chemical looping systems utilize oxygen carrier particles to perform the reduction–oxidation cycles, while Type II chemical looping systems utilize CO2 carrier particles to conduct carbonation–calcination cycles. The exergy analysis indicates that the chemical looping strategy has the potential to improve fossil fuel conversion schemes. Chemical looping particle performance and looping reactor engineering are the key drivers to the success of chemical looping process development. In this work, the desired particle characterization and recent progress in mechanism studies are generalized, which is followed by a discussion on the looping reactor design. This perspective also illustrates various chemical looping processes for combustion and gasification applications. It shows that both Type I and Type II looping processes have great potentials for flexible and efficient production of electricity, hydrogen and liquid fuels.

Syngas production on a Ni-enhanced Fe2O3/Al2O3 oxygen carrier via chemical looping partial oxidation with dry reforming of methane

This review aims to give more understanding of the selection and development of oxygen carrier materials for chemical looping. Chemical looping, a rising star in chemical technologies, is capable of low CO2 emissions with applications in the production of energy and chemicals. A key issue in the further development of chemical looping processes and its introduction to the industry is the selection and further development of an appropriate oxygen carrier (OC) material. This solid oxygen carrier material supplies the stoichiometric oxygen needed for the various chemical processes. Its reactivity, cost, toxicity, thermal stability, attrition resistance, and chemical stability are critical selection criteria for developing suitable oxygen carrier materials. To develop oxygen carriers with optimal properties and long-term stability, one must consider the employed reactor configuration and the aim of the chemical looping process, as well as the thermodynamic properties of the active phases, their interaction with the used support material, long-term stability, internal ionic migration, and the advantages and limits of the employed synthesis methods. This review, therefore, aims to give more understanding into all aforementioned aspects to facilitate further research and development of chemical looping technology.

Chemical looping (CL) process is a novel technology that separates oxygen from nitrogen to facilitate carbon dioxide capture in the design of clean coal power plants. The process, based on the multi-phase gas-solid flow, has an extremely challenging nonlinear multi-scale dynamics with jumps, rendering traditional robust control techniques, such as switching H-infinity design, difficult to apply and marginally successful. In an effort to model and control such a complex system, we present a generalized predictive control (GPC) scheme based on multiresolution wavelet model structure that characterizes well the nonlinear dynamics of single loop gas/solid flow. The NARX model, nonlinear in the wavelet basis, but linear in parameters, is used for the online chemical looping process identification. The control inputs and wavelet model parameters are calculated by optimizing the cost function using a gradient descent method. The convergence of the proposed GPC scheme is derived using Lyapunov function. Experimental results are provided to demonstrate the effectiveness of the proposed control strategy.