Sorption Enhanced Steam Methane Reforming Research Articles

Multicycle sorption enhanced steam methane reforming with different sorbent regeneration conditions: Experimental and modelling study

Replacing coal and oil with natural gas reduces greenhouse gas emissions without weakening economic development. Sorption enhanced steam methane reforming (SESMR) is an emerging process for an affordable transition towards cleaner energy systems, as it exploits natural gas coupled with in-situ CO2 capture to produce hydrogen. SESMR is performed on a steam reforming catalyst and a sorbent (cyclically regenerated by calcination) or, alternatively and more efficiently, on bi-functional Combined Sorbent-Catalyst Materials (CSCM). A double fluidized bed (reformer and oxyfuel combustor for calcination) with circulation of particulate material is anticipated for continuous SESMR at commercial scale. In this work, a Ni-CaO-mayenite CSCM was investigated in multicycle experimental tests under mild (pure N2, 850 °C) and severe (pure CO2, 925 °C) regeneration conditions, in thermogravimetric analysis for CO2-capture/regeneration and in an automated packed bed test rig for SESMR/calcination: the evolution of Ni and CaO functionalities as functions of cycle number was highlighted, also with the aid of scanning electron microscopy. Moreover, experimental results obtained with the hybrid material, collected under mild regeneration conditions, were used to simulate both CO2 sorption in TGA and packed bed SESMR multicycle tests: a Particle Grain Model (PGM) and an Axial Dispersion Plug Flow Reactor (ADPFR) model were integrated numerically, respectively. The same parameter values needed to characterize the material behaviour allowed a good fitting of both types of multicycle tests, thus demonstrating the possibility to use CO2-capture TGA data as a predictive tool for the CSCM performance in SESMR, provided that the catalytic activity is preserved.

Parametric study of hydrogen production via sorption enhanced steam methane reforming in a circulating fluidized bed riser

Computational fluid dynamics was applied for sorption enhanced steam methane reforming (SESMR) operating in a circulating fluidized bed (CFB) riser. The solid mixtures consisted of Ni-based catalyst and CaO sorbent. The aim of study was to design a proper pilot-scale CFB riser which produced hydrogen (H2) with both high purity and high flux. The design parameters and the reaction parameters were examined with 2k full factorial design. The significances of each parameter were analyzed by analysis of variance. Using the optimum result, the highest H2 purity reached 98.58% in dry basis accompanied with the highest H2 flux of 0.301 kg/m2 s. The hydrodynamics of this optimum case showed that SESMR was nearly completed since 5.0 m height because axial and radial distributions of solid were well developed without excessive segregation between catalyst and sorbent. Thus, the H2 purity and the H2 flux approached fully developed within the riser height.

Development of a Ni-CaO-mayenite combined sorbent-catalyst material for multicycle sorption enhanced steam methane reforming

This paper deals with a Ni-CaO-mayenite combined sorbent-catalyst material (CSCM) for sorption enhanced steam methane reforming (SESMR), with Ni and CaO fractions optimized for a multicycle SESMR/sorbent regeneration process (10 wt% and 13.5 wt% respectively). The CSCM was purposely synthesized by wet mixing followed by wet impregnation. Used characterization methods were XRD, BET and BJH methods, SEM/EDS, STEM/EDS, TPR, TGA. The CSCM reactivity was checked by a 3 h reforming test in a microreactor. The material was then subjected to two hundred and five SESMR/regeneration cycles utilizing a fully automated bench scale rig with a packed bed reformer/calciner reactor: a very stable and satisfactory performance was observed, without decline of Ni catalytic activity and CO2 sorption capacity over a 15 days no-stop test. This stability towards multicycle operation was confirmed by after-test characterizations.

GRAMS: A general framework describing adsorption, reaction and sorption-enhanced reaction processes

We present a generalized reaction-adsorption modeling and simulation (GRAMS) framework that captures both reaction and adsorption dynamics in columns with solid catalysts, porous adsorbents or both. It is based on a 1-dimensional, pseudo-homogeneous, non-isothermal, non-adiabatic and non-isobaric model that is extensively validated using experimental data from literature for different adsorption-reaction systems. For demonstrating the capabilities of the high-fidelity framework, simulations are performed for several configurations of a packed-column system containing (i) pure catalyst as in a fixed bed reactor, (ii) pure adsorbent as in a multi-step pressure swing adsorption (PSA) process, (iii) homogeneously-distributed uniform mixture of adsorbent and catalyst as in a cyclic sorption enhanced reaction process (SERP), and (iv) heterogeneously-compartmentalized adsorbent and catalyst as in a layered SERP. The model predictions show good agreement with experimental observations for sorption-enhanced steam methane reforming (SE-SMR), sorption-enhanced water gas shift reaction (SE-WGSR), PSA processes and conventional SMR. The framework is also used for evaluating the performance of a novel process with integrated SE-SMR and reverse water gas shift reaction (RWGSR) for direct natural-gas-to-syngas conversion. GRAMS is implemented such that it can be used for optimal design and intensification of novel, modular and multi-functional processes by combining multiple phenomena within a single unit.

Optimal synthesis of periodic sorption enhanced reaction processes with application to hydrogen production

A systematic design and synthesis framework for multi-step, multi-mode and periodic sorption-enhanced reaction processes (SERP) is presented. The formulated nonlinear algebraic and partial differential equation (NAPDE)-based model simultaneously identifies optimal SERP cycle configurations, design specifications and operating conditions. Key modeling contributions include a generalized boundary-condition formulation and a representation that enables the selection of discrete operation modes and flow directions using continuous pressure variables. A simulation-based constrained grey-box optimization strategy is employed to obtain optimal cycles and design parameters. The framework has been used for designing two SERP systems, namely sorption-enhanced steam methane reforming (SE-SMR) and sorption-enhanced water gas shift reaction (SE-WGSR), for maximizing hydrogen productivity and minimizing hydrogen-production cost. Specifically, a cyclic SE-SMR process is designed that obtains 95% pure hydrogen from natural gas with 35% higher productivity and 10.86% lower cost compared to existing small-scale, distributed systems. The developed synthesis framework can also be applied for other applications.

Modelling of sorption-enhanced steam methane reforming in a fixed bed reactor network integrated with fuel cell

In this study sorption-enhanced steam methane reforming (SE-SMR) in fixed beds is investigated by means of 1D numerical modelling, and the model is validated with the data reported in the literature. Isothermal conditions (973 K) are considered, and the equilibrium between the carbonation and calcination stages is shifted by a pressure swing: 3.5 · 106 Pa and 1013 Pa, respectively. The results showed that under these operating conditions at least 8 reactors in parallel are required to continuously produce a high-purity stream of H2, and a separated stream of concentrated CO2. The average H2 purity is 0.92, whilst the average H2 yield and selectivity are 2.9 molH2 molCH4−1 and 90%, respectively. A thermodynamic analysis was performed, which highlighted that, by using a portion of the produced H2 (about 0.4 molH2 molCH4−1), it is possible to fully cover heat and power demands of the process, making it completely energy self-sufficient. In the case when the proposed SE-SMR is integrated with a solid oxide fuel cell, net power generation at the scale of ∼950 kWel can be achieved with a net efficiency of the entire system of 51%, with the important feature that CO2 is concentrated.

Sorption-enhanced steam-methane reforming with simultaneous sequestration of CO2 on fly ashes – Proof of concept and simulations for gas-solid-solid trickle flow reactor

Applicability of fly ashes (FA) as CO2 acceptors in the integrated sorption-enhanced steam-methane reforming (SESMR) process carried out to produce the hydrogen was investigated. In such an integrated process, despite of reversibility of employed reactions, an in-situ adsorption of CO2 makes it possible to achieve almost total conversion of methane and produced CO. Therefore, hydrogen of high purity can be obtained directly from a single-step adsorptive reactor. Fly ashes from power plants, as they are cheap waste, do not have to be regenerated after saturation with CO2 and can further be directly utilized, so economic efficiency of hydrogen production process can significantly be improved. Also ecological aspects of this process are ameliorated, because almost all CO2 emitted during such hydrogen production is permanently sequestrated.Series of experiments have been carried out in the laboratory tubular fixed packed bed reactor to successfully proof the proposed concept. Then, the gas-solid-solid trickle flow reactor (GSSTFR) has been proposed as a promising solution to carry out effectively the considered process in an industrial scale. The mathematical model of this reactor has been formulated, then with the results of performed simulations the practical indications for further experimental investigations have been obtained.

Catalytic steam methane reforming enhanced by CO2 capture on CaO based bi-functional compounds

Sorption enhanced steam methane reforming (SE-SMR) was performed to maximize hydrogen production and contemporary remove CO2 from the product stream using bi-functional sorbent-catalyst compounds. Samples were tested at two different scales: micro and laboratory. The CaO amount varied in the CaO–Ca12Al14O33 sorbent system synthesized by wet mixing (CaO content of 100 wt%, 56 wt%, 30 wt%, or 0 wt% and balance of Ca12Al14O33) which were upgraded to bi-functional compounds by impregnation of 3 wt% of Ni. Nitrogen adsorption (BET/BJH), X-Ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and Scanning and Transmission Electronic Microscopy (SEM and TEM, respectively) analyses were performed to characterize structural and textural properties and reducibility of the bi-functional materials and evaluate their catalytic behavior. A fixed sorbent composition CaO–Ca12Al14O33 (56 wt% of CaO and Ca12Al14O33 balance), was chosen to study the effect of different weight hourly space times (WHST) and CH4 stream compositions in SE-SMR activity. Impregnated mayenite at both micro and laboratory scales showed stable H2 content of almost 74%, with CH4 conversion of 72% similarly to the values reported by the sample containing 30 wt% of CaO in the post-breakthrough.Sample with 30 wt% of CaO showed promisingly behavior, enhancing H2 content up to almost 94.5%. When the sorption enhanced reaction is performed roughly 89% of CH4 conversion is achieved, and after the pre-breakthrough, the catalyst worked at the thermodynamic level. During cycling sorption/regeneration experiments, even if CO2 removal efficiency slightly decreases, CH4 conversion and H2 yield remain stable.

Computationally efficient CFD model for scale-up of bubbling fluidized bed reactors applied to sorption-enhanced steam methane reforming

Sorption-Enhanced Steam Methane Reforming (SE-SMR) represents a novel and energy-efficient hydrogen production route with in situ CO2 capture. A comprehensive Eulerian-Eulerian CFD model of SE-SMR in a bubbling fluidized bed reactor, that uses dolomite and other solid sorbents as CO2 acceptors, has been developed. Kinetic models for steam methane reforming and CO2 capture have been implemented. In addition, a new particle drag model has been derived from customary formulas in order to reduce the computational cost. Two different scales have been studied: laboratory and semi-industrial. Results of the computation are in good agreement with literature data at both scales (SMR H2=76–78% vs. SE-SMR H2=90–96% dry basis mole fraction). Numerical simulations demonstrate that CO2 capture is the kinetic limiting step of the SE-SMR mechanism, as compared to steam methane reforming. Temperature is shown to be the key parameter of the SE-SMR chemical process at large scales, and an optimal T=625°C is estimated. Additionally, compared with the classical approaches, the new drag model provides seemingly realistic predictions within the multiple bubble regime, at a low computational cost and using a coarse grid. This represents a further advance for the scaling-up of the reactor to industrial sizes based on numerical simulation.

Sorption enhanced steam methane reforming on catalyst-sorbent bifunctional particles: A CFD fluidized bed reactor model

Sorption Enhanced Steam Methane Reforming (SE-SMR) has been proposed as an efficient novel technology to increase hydrogen yield and reduce the environmental footprint in comparison to state of art H2 production processes. Sorbent/catalyst materials characterized by stable behaviour over multiple reforming/calcination cycles may ensure to achieve almost stationary operating conditions utilizing a dual fluidized bed system (the reformer and the sorbent regenerator) with a solid circulation loop. Bifunctional, Combined Sorbent-Catalyst Materials (CSCM) are under development to integrate endothermic catalytic reforming and heterogeneous CO2 sorption in one particle, decrease mass and heat transfer resistances and reduce the solid hold-up in the reactors.This paper deals with the numerical simulation of a pilot scale bubbling fluidized bed SE-SMR reactor by means of a Two-Dimensional Computational Fluid-Dynamic (2D CFD) approach. The hydrodynamic picture is supplemented with a comprehensive Particle Grain Model (PGM) previously developed to describe the kinetics of catalytic and sorption functions, and successfully validated with micro-reactor reactivity tests and multi-cycle thermo-gravimetric sorption tests. The effect of repeated carbonation-calcination steps (the “history” of the granular material) is included in the computation of the reactor performance by utilizing the appropriate size of the sorbent grains in the carbonation rate expression.The numerical results show quantitatively the positive influence of carbon dioxide sorption on the reforming process, at different operating conditions, specifically the enhancement of hydrogen yield and reduction of methane residual concentration in the reactor outlet stream. A preliminary validation of CFD simulations is also carried out utilizing experimental data obtained from a pilot scale bubbling fluidized bed SE-SMR reactor (total bed mass≈14kg).An estimate is provided for the inward heat flow that would be required to operate the reactor in stationary temperature conditions: it is substantially reduced by the exothermic sorption process and could be satisfied by means of the solid circulation loop connecting the SE-SMR reactor to the high temperature calciner in the whole dual fluidized bed system.

Techno-economic analysis of sorption-enhanced steam methane reforming in a fixed bed reactor network integrated with fuel cell

Sorption-enhanced steam methane reforming (SE-SMR) is a promising alternative for H2 production with inherent CO2 capture. This study evaluates the techno-economic performance of SE-SMR in a network of fixed beds and its integration with a solid oxide fuel cell (SE-SMR-SOFC) for power generation. The analysis revealed that both proposed systems are characterised by better economic performance than the reference systems. In particular, for SE-SMR the levelised cost of hydrogen is 1.6 €⋅kg−1 and the cost of CO2 avoided is 29.9 €⋅tCO2−1 (2.4 €⋅kg−1 and 50 €⋅tCO2−1, respectively, for SMR with CO2 capture) while for SE-SMR-SOFC the levelised cost of electricity is 0.078 €⋅kWh−1 and the cost of CO2 avoided is 36.9 €⋅tCO2−1 (0.080 €⋅kWh−1 and 80 €⋅tCO2−1, respectively, for natural gas-fired power plant with carbon capture). The sensitivity analysis showed that the specific cost of fuel and the capital cost of fuel cell mainly affect the economic performance of SE-SMR and SE-SMR-SOFC, respectively. The daily revenue of the SE-SMR-SOFC system is higher than that of the natural gas-fired power plant if the difference between the carbon tax and the CO2 transport and storage cost is > 6 €⋅tCO2−1.

High Purity Hydrogen with Sorption-Enhanced Steam Methane Reforming in a Gas–Solid Trickle Bed Reactor

A sorption enhanced-steam methane reforming (SE-SMR) process was investigated in a countercurrent gas–solid trickle flow reactor packed with regularly stacked catalyst. The stacked catalyst was made of corrugated Pt/Ni/Al2O3 plates in the form of static mixers. Experiments were carried out in a temperature range of 550–600 °C, total pressure of 4.0 bar, and water to methane ratio of 4.0 in the reactor feed. Within the investigated conditions, experimental results offered a solid proof of concept for new continuous SE-SMR operation for production of hydrogen where sorbent can be regenerated separately from the catalyst. Experimental data were reasonably well described by a plug flow model for both the gas and solid phases. The mathematical model was further used to optimize the continuous SE-SMR operation: it could be demonstrated that the level of the hydrogen purity in the reactor exit stream could be controlled by a multistage reactor consisting of alternating catalytic active and stainless-steel inert ...

Self-sustained process scheme for high purity hydrogen production using sorption enhanced steam methane reforming coupled with chemical looping combustion

Chemical looping processes with their inherent feature of CO2 sequestration are found to be promising in developing alternative combustion and reforming technologies that are cleaner and safer. In the present work, a novel, self-sustained, efficient process scheme has been proposed for the production of high purity hydrogen by integrating sorption enhanced steam methane reforming (SESMR) with chemical looping combustion (CLC) and by incorporating heat recovery steam generation (HRSG) as well as power generation sections. The integration between SESMR and CLC is proposed with the objectives of increasing H2 productivity, reducing CO2 emission while effectively conserving the process heat, which is achieved by coupling fuel reactor flue gases with reformer and air reactor outlet gases with regenerator. Thermodynamic investigation of the proposed process is carried out based on a steady state plant wide model developed using ASPEN Plus. Further, sensitivity analysis is carried out to analyse the process performance and to evaluate the optimum operating parameters. The results demonstrate the improved performance of proposed scheme over existing processes in terms of exhibiting 98.05% H2 purity, 95.1% CO2 capture efficiency along with 70.3% energy and 68.24% exergy efficiencies.

Comprehensive Analysis of Sorption Enhanced Steam Methane Reforming in a Variable Volume Membrane Reactor

The use of combined reaction-separation processes in steam methane reforming (SMR) has recently received significant attention as an enticing route to meet the challenging requirements of distributed hydrogen production for fuel cell vehicles. While many of the investigations in recent literature focus solely on either CO2 adsorption or selective H2 membrane permeation to reduce the reactor footprint and the temperature required to drive the endothermic reaction in continuous flow reactors, the CHAMP-SORB is a new variable volume, transient batch reactor technology that utilizes both strategies simultaneously. Building upon our prior study in which we experimentally demonstrated the viability of CHAMP-SORB reactor concept on bench scale, this work focuses on understanding the heat/mass transfer and reaction/separation interactions to develop guidelines for the reactor scale-up. A combined transport-kinetic model is developed, including spatial variations of SMR reaction and CO2 adsorption rates within the...

Core-shell structured CaO-Ca9Al6O18@Ca5Al6O14/Ni bifunctional material for sorption-enhanced steam methane reforming

Sorption-enhanced steam methane reforming (SESMR) is a promising technology for H2 production, which can be further enhanced at the particle scale by using core (sorbent)-shell (catalyst) structured bifunctional materials. However, it is challenging but desirable to develop such materials with high activity and stability. In this work, three core-shell structured CaO-Ca9Al6O18@Ca5Al6O14/Ni bifunctional materials with varying CaO content and core/shell mass ratio were prepared by a two-step sol-gel method, and two others (Ni/CaO and CaO@Ca5Al6O14/Ni) served as references. The structural properties and catalytic performance of the materials were investigated. The results showed that all core-shell materials during cyclic SESMR operation had much better performance than Ni/CaO with regards to activity, stability and CaO utilization, and CaO-Ca9Al6O18@Ca5Al6O14/Ni was generally superior to CaO@Ca5Al6O14/Ni except when the former had a much higher CaO content than the latter. The excellent performance of CaO-Ca9Al6O18@Ca5Al6O14/Ni was mainly due to the stabilization effect of Ca9Al6O18 and the support effect of Ca5Al6O14. The best material was a CaO-Ca9Al6O18@Ca5Al6O14/Ni with a CaO content of 13wt% and a core/shell mass ratio of 0.2, showing high activity and stability over 60 SESMR cycles while maintaining nearly complete utilization of CaO.

Numerical modelling and simulation of hydrogen production via four different chemical reforming processes: Process performance and energy requirements

AbstractMethane reforming operated in fluidized bed reactors is modelled and simulated for four different chemical processes: Steam Methane Reforming (SMR) process and the both non‐commercially available Sorption‐Enhanced Steam Methane Reforming (SE‐SMR) process and Chemical Looping Reforming process for non‐autothermal (naCLR) as well as autothermal (aCLR) operation. These processes are operated at relevant operating conditions. The results from the reforming simulations are used as input in a Pressure Swing Adsorption model, where the hydrogen is further purified to about 99.99 % and delivered at 2500 kPa (25 bar) of pressure and 25 °C. The energy consumption for hydrogen production on a mole basis is calculated for each chemical process with and without heat recuperation, with heat recuperation referring in this context to the utilization of the thermal energy available from the cooling of certain fluid streams to power other parts of the process.

Sorption enhanced steam methane reforming by Ni–CaO materials supported on mayenite

Sorption enhanced steam methane reforming (SESMR), i.e. SMR with in situ CO2-sorption, can lead to a sustainable and economical exploiting of natural gas for hydrogen production, with high purity and simultaneous sequestration of greenhouse gases. CaO-mayenite CO2-sorbents, Ni-mayenite SMR catalysts and Ni–CaO-mayenite combined sorbent catalyst materials (CSCM) for SESMR were synthesized by wet mixing and wet impregnation methods, and characterized by means of XRD, BET/BJH, SEM/EDS, and TPR. For CSCM, an influence of CaO load on textural and Ni reducibility properties was recorded. Materials sorption capacity was measured in multicycles sorption/regeneration TGA tests: it always underwent a stabilization with cycle number increase. Reforming tests in micro-reactor scale were performed on 3 wt% to 10 wt% Ni-mayenite and selected CSCM: all Ni-mayenite always shown good performances, while for CSCM a detrimental role of CaO load on Ni catalytic activity was evidenced.

Sorption enhanced catalytic Steam Methane Reforming: Experimental data and simulations describing the behaviour of bi-functional particles

Steam Methane Reforming (SMR) combined with simultaneous CO2 sorption is a convenient reaction path to enhance H2 yield, leading to more favourable thermodynamic conditions and reducing environmental footprint. In order to obtain an efficient integration of exothermic and endothermic reactions and minimize physical resistances, bi-functional catalyst-sorbent materials are under development, containing both CaO sorbent grains and nickel catalytic sites.Solo-sorbent, solo-catalyst and bi-functional materials were synthetized at laboratory scale. In this work, they are studied by means of thermogravimetric and packed bed micro-reactor tests, to highlight both catalytic and sorption functions, and their mutual interactions.Experimental results are simulated by a Particle Grain Model (PGM), conceived by Stendardo and Foscolo (2009) for solo-sorbent particles, and more recently extended to Sorption Enhanced SMR (SE-SMR) processes by Aloisi et al. (2016). For micro-reactor simulations, PGM is supplemented by molar balances of gaseous components surrounding the granular bed, assuming an Axial Dispersion Plug Flow Reactor approach.The sorption and catalytic behaviour of synthesized materials is successfully described by this model, for the first time. Initial decline and subsequent stabilization of CO2 sorption capacity as a function of repeated carbonation cycles, as well as the whole dynamic sorption behaviour in each cycle, is simulated by varying just one model parameter, the sorbent grain size. SMR Numaguchi and Kikuchi (1988) kinetics, plugged in PGM, predicts accurately H2 yield, CH4 conversion, and weight hourly space velocities allowing thermodynamic equilibrium or kinetic regime at the micro-reactor exit. In SE-SMR tests, the breakthrough characterizing outlet gas concentrations as functions of time, exhibited by fresh samples of bi-functional materials, is well described by model calculations, spanning the whole range between SE-SMR and SMR equilibria.

Modelling of binary fluidized bed reactors for the sorption‐enhanced steam methane reforming process

ABSTRACTA 1 m high laboratory‐scale and a 4 m high industrial‐scale sorption‐enhanced steam methane reforming (SE‐SMR) fluidized bed reactor were simulated using a three‐fluid model. The performance of the SE‐SMR process was compared with the steam methane reforming (SMR) process. The influences of the superficial gas velocities and the solid loading (packed bed heights) on the reactor performance (hydrogen purity) were studied. The simulation results show that a higher purity of the hydrogen product can be obtained in a SE‐SMR reactor. The superficial gas velocity is an important parameter. In the present study, it has been found that the binary sorbent‐catalyst particles are well mixed when the bed is operated at m/s. The sorbent can adsorb CO steadily, thus the dry mole fraction of the hydrogen product can get above 0.95 in the 1 m laboratory‐scale bed, and above 0.97 in the 4 m industrial‐scale bed. However, when the laboratory scale bed is operated at a lower superficial gas velocity of m/s, the binary sorbent‐catalyst particles are segregated. When the bed is operated at a higher superficial gas velocity of 0.3 m/s, the process work load is increased, and the gas residence time in the reactor is decreased. Therefore, the hydrogen product purity is further decreased. The simulation results also show that there is an optimal bed height limit for the 4 m industrial‐scale bed, at which further increase of the packed bed height cannot increase the hydrogen purity.

Sol-gel-derived, CaZrO3-stabilized Ni/CaO-CaZrO3 bifunctional catalyst for sorption-enhanced steam methane reforming

Sorption-enhanced steam methane reforming (SESMR) that combines steam reforming of methane with in situ CO2 removal is a promising technology for H2 production, and bifunctional catalysts that integrate catalytic and absorptive sites into one body are believed to have reduced mass transfer resistances. However, it is still a challenge to prepare bifunctional catalysts with high stability. Here, we used a sol-gel technique based on the formation of citrate complexes to prepare a series of Ni/CaO-CaZrO3 bifunctional catalysts in which Ni, CaO and CaZrO3 acted as catalyst, sorbent and stabilizer, respectively. The stabilizer, Ni loading and CaO content had a direct effect on the structure and morphology of the catalyst, which in turn influenced its CO2 uptake and SESMR performance. Compared to Ni/CaO, the CaZrO3-stabilized Ni/CaO-CaZrO3 had smaller and fluffier grains, showing not only higher CO2 uptake and better stability in 50 carbonation-calcination cycles, but also higher stability during cyclic SESMR process. In particular, the catalyst with a Ni loading of 15wt%, CaO content of around 60wt% and CaZrO3 content of 25wt% presented the best SESMR performance by taking into account the catalytic activity and stability as well as the duration of the prebreakthrough period. However, the best catalyst was still subject to slow deactivation during a long-term stability test (up to 90 SESMR cycles), which was mostly due to the smooth and compact shell formed on the catalyst surface. The partially deactivated catalyst can be effectively reactivated by an additional carbonation step during the cyclic SESMR operation.