Methane is a potent greenhouse gas, and mitigating its substantial emissions, primarily from coal mines with low concentrations, is among the most effective strategies to slow global warming. Catalytic combustion using transition metal oxides is increasingly pivotal in addressing this issue; however, the low-temperature activity of these catalysts limits their widespread application. In this study, we aimed to develop highly active and costeffective catalysts for large-scale combustion of low-concentration methane. To this end, a series of transition metal oxides (Cr2O3, Mn2O3, Fe2O3, Co3O4, NiO, and CuO) supported on open cell foams were synthesized, and their catalytic performance for methane combustion at 1 vol% CH4 was assessed in a fixed-bed reactor. Comprehensive characterization was conducted using XRD, SEM-EDS, XPS, H2-TPR, and O2-TPD techniques to elucidate the underlying mechanisms of CH4 catalytic combustion. Results demonstrated that the structured catalysts exhibited exceptional activity and thermal stability. Among them, NiO showed the highest activity, followed by Fe2O3 and Co3O4 with similar activity, and then Mn2O3, CuO, and Cr2O3 showing progressively lower reactivities. Complete CH4 conversion was achieved over NiO at approximately 500 degrees C, comparable to certain noble metal catalysts. The superior catalytic activity was attributed to the abundant reactive oxygen species, originating from chemically adsorbed oxygen and surface lattice oxygen transformations. Additionally, the rich oxygen vacancies facilitated CH4 dissociation and enhanced activity. This study provides an effective framework for advancing catalyst design to improve methane oxidation efficiency, thereby enhancing the practical management and utilization of low-concentration methane emissions from coal mining activities.

Designing an efficient system for conversion of fossil fuel to hydrogen with lower environmental impact represents a promising strategy to meet the demands of a low-carbon future society. This study introduces an integrated chemical looping system combining hydrogen production and combustion for low-carbon fossil fuel conversion. The system achieves hydrogen production at 600 degrees C, significantly lower than conventional steam methane reforming (850 degrees C). Moreover, chemical looping combustion is employed to enable efficient CO2 capture. The proposed system is investigated from key reactions, system performance, and economic feasibility aspects. Experimental results show 80 % methane conversion, a hydrogen yield of 2.6 in the hydrogen production process, and nearly 100 % CO2 purity from purge gas combustion. Thermodynamic analysis reveals the energy and exergy efficiencies of 74.3 % and 68.9 %, surpassing the reference system by 3.6 % and 4.1 %, respectively. Economic assessment indicates a 10 % reduction in the levelized cost of hydrogen compared to the reference system. 1000 consecutive cycles confirm the outstanding stability of the oxygen carrier particles for the system. This study demonstrates the system's feasibility, cost-effectiveness, and potential for sustainable hydrogen production with minimal environmental impact, introducing a promising method for the efficient utilization of fossil fuels.

Carbon black‐loaded activated carbon (CB‐loaded AC) is a cost‐effective catalyst for CH 4 decomposition to produce H 2 . CB induces defects on the AC surface, enhancing catalytic activity. Current studies on the role of defects in promoting CH 4 decomposition are primarily experimental, with unclear mechanisms. Hence, exploring the reaction mechanism of defects in CH 4 decomposition is crucial. In this work, the Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) are used to construct defects (Mono‐Vacancy defect, Di‐Vacancy defect, and Stone‐Wales defect) on the AC surface, determining the catalytic mechanism of defects in CH 4 decomposition. The results show that during the CH 4 decomposition (C─H bond cleavage) phase, defective AC reduces the energy barriers for CH 4 decomposition. Under identical conditions, the rate‐determining step of C─H bond cleavage in CH 4 occurs more readily on AC with Mono‐Vacancy, Di‐Vacancy, and Stone‐Wales defects, with corresponding reductions in energy barriers of 4.64, 2.36, and 3.12%, respectively. The total energy barriers for the reaction are reduced by 12.95, 27.58, and 8.43%, respectively. This indicates that the defects significantly lower the energy barrier for CH 4 decomposition, thereby facilitating the reaction and confirming that these defects act as active sites for the catalytic decomposition of CH 4 on AC.

Methane is a potent greenhouse gas that poses a significant environmental challenge due to the large-scale release of low-concentration methane (LCM) during coal mining operations. However, the difficulty in achieving stable combustion of LCM hampers its efficient utilization. In this study, a MnOx/Al2O3 porous media catalyst was synthesized using alumina foam ceramics as the support. The catalyst was characterized using FESEM-EDS, BET, XRD, and XPS. The effects of equivalence ratio, inlet velocity, and preheating temperature on combustion performance were systematically evaluated. The results demonstrated that increasing the preheating temperature significantly enhanced the catalytic performance of the MnOx/Al2O3 catalyst during the combustion process. At a preheating temperature of 150 degrees C, combustion stability was significantly improved, the lean flammability limit of methane was reduced to 0.35, and the maximum methane conversion rate exceeded 95.0 %. However, increasing the preheating temperature intensified the non-uniformity of the temperature distribution within the burner, leading to increased emissions of CO and NOx. A dual-stage preheating mechanism based on the porous media structure was proposed to explain the enhanced combustion performance. A catalytic combustion mechanism of methane over MnOx/Al2O3 was proposed, the Mn4+/Mn3+ redox cycle was identified as a key factor in maintaining catalyst activity. These findings provide valuable insights into the development of efficient catalysts and the integration of preheating strategies for LCM combustion, contributing to the effective control and utilization of coal mine methane emissions.

Chemical looping technology utilizes the redox process and catalytic effects of metal oxides to convert carbon-containing fuels and carbon dioxide into value-added chemicals. Currently, cation diffusion, sintering, agglomeration, and the inactivation of metal oxides during cyclic redox reactions are the key challenges hindering the widespread industrialization of the chemical looping. While encapsulation strategies using supports have shown potential for prolonging redox catalyst lifespan, the fundamental mechanisms of support-redox catalyst interactions and deactivation pathways under prolonged cycling remain elusive. In this study, the varying structural evolution pathways of redox catalysts from in situ transmission electron microscopy (TEM) indicate that the SiO2 shell can suppress Ostwald ripening during the reduction process through a confinement effect, thereby preventing the agglomeration of metal particles. Moreover, the activity-related size-dependent of Ni nanoparticles is elucidated through density functional theory (DFT) simulations. SiO2 support affects the migration path during the oxidation process. Finally, redox catalysts struggle to remain stably embedded within support or securely anchored on their surfaces. The continuous separation between Ni-Fe and support may serve as a critical factor in deactivation in the long-term. This study offers new insights into designing hierarchical redox catalysts with enhanced thermal and redox stability through in situ observation of the actual reaction process under high-temperature.

Porous media combustion (PMC) is considered as a feasible solution for addressing low-concentration methane (LCM) in coal mines. Conventional straight PM burners are suboptimal in ameliorating LCM combustion stability. Herein, a four-layer PM burner assembled with variable pore-density Al2O3 foam ceramics was designed to improve the combustion stability. The effects of PM arrangement, equivalence ratio (phi), and inlet velocity (v) on combustion performance was systematically evaluated. Finally, the heat transfer processes and oxidation pathways were also elucidated in details. The results indicated that the burner with a gradual pore-density PM configuration (40-30-20-10 PPI) achieved more uniform temperature distribution and superior combustion stability. The presence of flame buffer zone in the structure attenuated flame propagation speed and harmonized equivalence ratios and velocities to achieve an efficient dynamic heat balance, which is conducive to improving the stability of the combustion system under lean combustion conditions. At phi = 0.37, v = 0.104 m/s, the flame position was anchored near 60 mm with a moderate peak temperature of 834 degrees C and the maximum temperature of 811 degrees C were obtained with a flat rate of change of 0.02 similar to 0.07 degrees C/s. The flame still sustained the desirable submerged combustion with a final temperature of 144 degrees C under this lean combustion scenario. The pollutant emissions in the PMC process were overall at lower levels and the NOx emissions were lower than 3.60 ppm for all operating conditions. This study provides a worthy reference in designing and optimizing burner structures for stable and efficient combustion of LCM.

Catalytic decomposition of CH4 with iron-based catalysts is a promising approach for H2 production, but CO2 is generated in the catalyst regeneration via steam gasification or combustion to remove carbon deposition. Compared with normal iron-based catalysts, the utilization of Fe/CaO-based material as a catalyst exhibits higher CH4 conversion, higher H2 production, better regeneration performance and lower CO2 emission, due to the CO2 absorption by CaO improving carbon deposition conversion and H2 production via steam gasification in regeneration. The efficient and low-cost Fe/CaO-based material is a key. In this work, a novel, efficient and lowcost Fe/CaO-based solid waste material was prepared from red mud and carbide slag by the hydrothermal method. The cyclic catalysis performance in CH4 decomposition stage and carbon deposition steam gasification performance in regeneration stage of the material were investigated. The effects of Si, Al, Ti in the material on cyclic stability were determined. The material mainly consists of Fe0, CaO, CaAl2Si2O8, and CaTiO3. After removal of Na and K elements in red mud, the Fe/CaO-based solid waste material with 25 wt% red mud and 75 wt% carbide slag exhibits higher cyclic catalysis and regeneration performance. The average conversion of CH4 is 84.71% and the H2 production in the regeneration stage reaches 10.37 mmol/g in the 1st cycle. After 8 cycles, the average conversion of CH4 is 78.53%. H2 production performance in CH4 decomposition is promoted due to the perovskite structure of CaTiO3, which creates electron transfer channels on the crystal surface to promote the catalytic reaction. CaAl2Si2O8 improves the sintering resistance of the material. The material shows immense promise for resource utilization of hazardous waste, H2 production and CO2 capture.

Innovations in CO2 absorption devices play a vital role in advancing industrial applications of CO2 capture; increasing CO2 absorption rate and decreasing the absorber are important tasks in amine-based CO2 capture technologies. This study presents a novel absorber, a compact multiflow absorber, which employs cocurrent spray and traditional package. The integrated design of the spray and packed towers reduces the size of the absorber. By incorporating a cocurrent spray tower as the primary absorption unit, the absorber achieves higher CO2 removal efficiency and significantly cut down the amount of package needed in the traditional absorber. A comparison with reported counter-current spray tower demonstrated higher overall absorption rate for proposed cocurrent spray tower. The cocurrent spray tower has an overall absorption rate approximately 50% higher than the counter-current spray tower in the first 60 s. The new absorber obtained an efficiency at 86%; however, the traditional package is only 67%. The newly designed absorber increased the CO2 absorption efficiency by 28%. Finally, the relevance of each operational parameter was evaluated through orthogonal tests, while trend analysis elucidated the influence of various factors on the mass transfer evaluation indices.

The chemical looping hydrogen production (CLHP) process utilizing iron-based oxygen carriers holds promise for practical hydrogen generation applications. However, challenges persist in developing iron-based carriers that are easy to prepare and demonstrate effective reactivity. Our research focuses on evaluating the CLHP reaction performance using bimetallic Ni-Fe oxygen carrier particles, synthesized by a scalable mechanical mixing method. This study unravels the role of Ni in bimetallic Ni-Fe oxygen carriers and investigates the influence of varying nickel-doping ratios on enhancing the reduction reactivity of iron-based oxygen carriers. Compared to the undoped sample, the 20 wt% nickel-doped Fe2O3/Al2O3 (20NiFe) particles enabled a reduction in the reaction temperature by at least 50 K. With the dopant, the methane conversion rate at 923 K is 500% higher than that of carriers without the dopant. Heterogeneous kinetic analysis demonstrates that the global reduction reaction data for the Ni-Fe oxygen carriers fit with the nucleation-nuclei growth model. Through redox reactivity tests and reduction kinetic analysis, 20NiFe shows the lowest apparent activation energy at 53.93 kJ/mol. Furthermore, the kinetic study and quasi in-situ XRD analysis aid in proposing the evolution process of methane reduction reaction for nickel-doped iron-based oxygen carriers, clarifying the role of doping in improving chemical looping reactivity from a kinetic perspective. This work provides valuable guidance for the design and optimization of oxygen carriers, thus accelerating the readiness for industrial deployment of hydrogen production via chemical looping process.

The present investigation delves into the utilization of Mg6MnO8 modified with binary Li2WO4 and Na2WO4 tungstates as oxygen carriers for the chemical looping oxidative dehydrogenation (CL-ODH) of ethane. The Mg6MnO8-LiNaW2 oxygen carrier demonstrates remarkable performance, achieving up to 77.7 % ethane conversion, 86.5 % ethylene selectivity, and 67.2 % ethylene yield. HRTEM-EDS reveals the formation of a molten binary tungstates layer covering the solid Mg6MnO8 substrate. The molten binary tungstates layer effectively modulates the release of lattice oxygen in a step-wise manner during ODH reactions. oS analysis reveals that the doping of Li/Na binary tungstates inhibits the formation of OH-/CO32- and Mn4+ species, thus preventing the deep oxidation of ethylene. The Mg6MnO8-LiNaW2 sample maintains stable reactivity and surface morphology throughout 20 redox cycles. DFT calculations further indicate that the modification with Li/Na binary tungstates promotes electron accumulation around the local environment of the Me -O bond, thereby reducing the formation energy (Eo) of oxygen vacancy in Mg6MnO8 and improving the oxygen vacancy concentration within the bulk of the oxygen carriers. The superior ethylene selectivity of the Mg6MnO8-LiNaW2 oxygen carrier can be attributed to the higher oxygen diffusion capability in the bulk of the Mg6MnO8 core, coupled with the lower oxygen transport rate through the molten tungstates layer.

With the rapid development of industrialization, the emission of nitrogen oxides (NOx) has become a global environmental issue. Uranium is the primary fuel used in nuclear power generation. However, the production of uranium, typically based on the uranyl nitrate method, usually generates large amounts of nitrogen oxides, particularly NO2, with concentrations in the exhaust gas exceeding 10,000 ppm. High concentrations of nitrogen dioxide are also produced during silver electrolysis processing and the treatment of waste electrolyte solutions. Traditional V-W/TiO2 NH3-SCR catalysts typically exhibit high catalytic activity at temperatures ranging from 300 to 400 °C, under conditions of low NOx concentrations and high gas hourly space velocity. However, their performance is not satisfying when reducing high concentrations of NO2. This study aims to optimize the traditional V-W/TiO2 catalysts to enhance their catalytic activity under conditions of high NO2 concentrations (10,000 ppm) and a wide temperature range (200–400 °C). On the basis of 3 wt% Mo/TiO2, various loadings of V2O5 were selected, and their catalytic activities were tested. Subsequently, the optimal ratios of active component vanadium and additive molybdenum were explored. Simultaneously, doping with WO3 for modification was selected in the V-Mo/TiO2 catalyst, followed by activity testing under the same conditions. The results show that: the NOx conversion rates of all five catalysts increase with temperature at range of 200–400 °C. Excessive loading of MoO3 decreased the catalytic performance, with 5 wt% being the optimal loading. The addition of WO3 significantly enhanced the low-temperature activity of the catalysts. When the loadings of WO3 and MoO3 were both 3 wt%, the catalyst exhibited the best denitrification performance, achieving a NOx conversion rate of 98.8% at 250 °C. This catalyst demonstrates excellent catalytic activity in reducing very high concentration (10,000 ppm) NO2, at a wider temperature range, expanding the temperature range by 50% compared to conventional SCR catalysts. Characterization techniques including BET, XRD, XPS, H2-TPR, and NH3-TPD were employed to further study the evolution of the catalyst, and the promotional mechanisms are explored. The results revealed that the proportion of chemisorbed oxygen (Oα) increased in the WO3-modified catalyst, exhibiting lower V reduction temperatures, which are favorable for low-temperature denitrification activity. NH3-TPD experiments showed that compared to MoOx species, surface WOx species could provide more acidic sites, resulting in stronger surface acidity of the catalyst.

Porous media (PM) catalytic combustion offers a potential strategy for stable and efficient combustion of low-concentration methane (LCM). Herein, a porous media catalyst loaded with Fe2O3 as the active component (Fe2O3/Al2O3) was developed by ultrasonic-assisted impregnation for LCM catalytic combustion in a four-layer porous media burner. The influences of the gas flows, velocities, equivalence ratios, and PM arrangement patterns on the temperature distribution, combustion stability, methane conversion, and emissions were investigated in detail. The results indicated that the Fe2O3/Al2O3 catalyst possessed exceptional catalytic activity and thermal stability at medium-to-high temperatures, which broadened the limiting equivalence ratio for CH4 stationary combustion to 0.43 with the CH4 conversion exceeding 99 %. LCM enabled higher combustion stability in the PM burner with a gradually varied configuration, achieving steady combustion for more than 120 min under the lean combustion condition (0.43 equivalence ratio and 50 L/min). The high-quality flue gas from LCM catalytic combustion with an average temperature over 600 degree celsius, lower CO (< 150 ppm) and NOx emissions (< 10 ppm) could serve for the comprehensive utilization of power generation, heating, and cooling. The catalytic oxidation of LCM on the Fe2O3 surface was primarily divided into four steps with the second-step CH4 dehydrogenation in CH4 dissociation being the dominant rate-limiting step. This work proves that the catalyst fabricated by ultrasonic-assisted impregnation can effectively break through the lean combustion threshold, which provides a valiant reference for the clean and efficient utilization of LCM.

Chemical looping conversion shows great potential in the renewable energy sector. The successful execution of chemical looping conversions relies heavily on oxygen carrier, which is also referred to as the redox catalyst or metal oxide materials. The oxygen carrier supplies the necessary quantity of oxygen ions (specifically lattice oxygen) for the conversion of fuels during the process of reduction. The oxygen-deficient oxygen carrier is refilled with molecular oxygen from air in an oxidizer. The redox-driven ionic diffusion and the formation of surface oxygen vacancies leads to a modification in the microstructure and crystal-Structure of oxygen carrier particles, resulting in the development of a new local chemical environment and the creation of oxygen vacancies. These are considered as active sites in chemical looping. Significant research has been conducted in recent years to enhance the performance of oxygen carrier through the modulation of their component design, structural construction, and modification for different chemical looping conversions. Nevertheless, the oxygen carriers' micro-structure and crystal-structure has been given inadequate focus, encompassing aspects such as lattice deformation, site asymmetry, strength of Me-O bonds, and tilting of the crystal lattice, among others. The focus of this review is on the progress made in controlling the diffusion of ions, phase segregation, and manipulating the local chemical environment of O in oxygen carrier. These advancements will aid in the investigation of oxygen carrier for effective chemical looping conversion.

AbstractBy employing metal oxides as oxygen carriers, chemical looping demonstrates its effectiveness in transferring oxygen between reduction and oxidation environments to partially oxidize fuels into syngas and convert CO2 into CO. Generally, NiFe2O4 oxygen carriers have demonstrated remarkable efficiency in chemical looping CO2 conversion. Nevertheless, the intricate process of atomic migration and evolution within the internal structure of bimetallic oxygen carriers during continuous high‐temperature redox cycling remains unclear. Consequently, the lack of a fundamental understanding of the complex ionic migration and oxygen transfer associated with energy conversion processes hampers the design of high‐performance oxygen carriers. Thus, in this study, we employed in situ characterization techniques and theoretical calculations to investigate the ion migration behavior and structural evolution in the bulk of NiFe2O4 oxygen carriers during H2 reduction and CO2/lab air oxidation cycles. We discovered that during the H2 reduction step, lattice oxygen rapidly migrates to vacancy layers to replenish consumed active oxygen species, while Ni leaches from the material and migrates to the surface. During the CO2 splitting step, Ni migrates toward the core of the bimetallic oxygen carrier, forming Fe–Ni alloys. During the air oxidation step, Fe–Ni migrates outward, creating a hollow structure owing to the Kirkendall effect triggered by the swift transfer of lattice oxygen. The metal atom migration paths depend on the oxygen transfer rates. These discoveries highlight the significance of regulating the release–recovery rate of lattice oxygen to uphold the structures and reactivity of oxygen carriers. This work offers a comprehensive understanding of the oxidation/reduction‐driven atomic interdiffusion behavior of bimetallic oxygen carriers.

Porous media combustion (PMC) has made a comeback as a practical technology for the utilization of low-concentration methane (LCM) from coal mining. However, the conventional direct-fired PM burner still suffers from the rampart of flame stability and combustion efficiency not addressing industrial demands. Herein, a four-layer gradually-varied porous burner was innovatively developed for LCM combustion to investigate combustion performance under lean combustion conditions (CH4 volume fraction below 5 %). The methane conversion, pollutant emissions, and flue gas temperature were also evaluated in detail. The results indicated that the burner offered a favorable combustion resistance due to the gradually-varied PM arrangement to heighten combustion stability with subtle temperature fluctuation and flame migration. The flammability limit of LCM was extended to the lowest equivalence ratio of 0.43 with stationary combustion at 240 °C for 120 min. The energy efficiencies of the LCM combustion under lean combustion conditions were greatly boosted with the highest combustion and thermal efficiencies attained at 99.52 % and 70.05 %, respectively. The maximum 99.93 % CH4 conversion was acquired at an equivalence ratio of 0.45 and a flow rate of 80 L/min. LCM combustion in the burner achieved extremely low pollutant emission levels and the overall CO and NOx emissions were 58.04 ppm and below 23 ppm respectively under the experimental conditions. In addition, the high-quality flue gas with an average temperature of more than 516 °C was detected in the operating process, which allowed the available heat utilization at the coal mine scenes or in other industries.

As a typical fluidization technology, Fluid Catalytic Cracking (FCC) is faced with the problem of catalyst particle abrasion and crushing. However, due to the small particle size of catalyst particles and the complex flow in the reactor, it is difficult to study the flow, collision, and crushing characteristics of catalyst particles by experimental methods. In order to reveal the flow, collision, and crushing characteristics of catalyst particles in FCC reactor, the crushing models of single particle Abt(10) and all particles were established. By tracking the particle breakage process, the particle size distribution after particle breakage was obtained, the abrasion type of particles was determined, and the energy conversion path of particles was clarified. It was found that a few sub-particles inherit most of their mechanical energy after single particle crushing, and it was speculated that most of the dissipated mechanical energy comes from the transformation of particle rotation energy to internal energy. In the simulation of all particle crushing processes, the overall particle crushing probability is 3.90%, and the particle size distribution curve after crushing shows a bimodal distribution. Considering the abrasion mechanism, it is mainly dominated by the surface peeling mechanism.

The exponential development of new electric vehicles has led to the inevitable retirement of lithium-ion batteries as a power source. Recovery of spent lithium-ion batteries (LIBs) with remarkable resource and pollution characteristics is an essential solution to alleviate the shortage of lithium resources and drive the sustainable industrial development. Herein, a novel strategy was proposed as chemical looping complementary reduction (CLCR) for recycling valuable metals from spent LiCoO2 battery as chemical-looping cyclic carriers. The influ-encing factors of reduction temperature, time and H-2 flows on reduction characteristics of LiCoO2 carriers were investigated on a laboratory-scale fixed bed. The results indicated that both high temperature and elevated H-2 flows were conduce to enhancing LiCoO2 conversion with fairly high crystallinity and purity of reduction products (mainly Li2O and Co monomers) and 98.36 % conversion of LiCoO2 was attained at 1000 degrees C for 120 min with the H-2 flow of 60 mL/min. Thermodynamic analysis proved that complementary matching properties existed between reduction temperature and H-2 concentration affecting the phase equilibrium of products, while 650 degrees C similar to 900 degrees C was favorable to obviate the formation of liquid LiOH and the loss of target products. Finally, the mechanism of CLCR along with its environmental and economic impacts were insightfully elaborated to provide a technical and cost-efficient scheme for spent LIBs recycling.

Experimental studies on co-pyrolysis of coal and lignin are carried out on a fixed-bed reactor to investigate composition and transformation of the co-pyrolysis products. The results show that co-pyrolysis reduces yield of char and promotes yield of gas, the maximum pyrolysis gas yield increases by 33.1%. Co-pyrolysis has a significant promotion effect on generation of CH4 and CO. The interaction between the pyrolyzed volatile fractions of coal and lignin shows the most pronounced interaction at a coal to lignin mixing ratio of 1:1, and the pyrolysis tar yield shows a positive synergistic effect. Guaiacols are converted to monophenols and bisphenols during the co-pyrolysis process. Content of monophenols and bisphenols increase by 2.9% and 9.8%, respectively, while content of guaiacols decreases by 5.1% compared with the theoretically calculated values. The breakage of carbonyl and carboxyl groups, and the interaction with volatile components are enhanced, which inhibits formation of ethers, aldehydes and acids, and promotes generation of phenols, release of oxygenated gases and stabilization of pyrolysis tar. The introduction of lignin into coal pyrolysis also significantly promotes the upgrading of tar in which light components is nearly 90%.

Coupling chemical looping steam methane reforming (CL-SMR) with sorbents comprises a promising approach for enhancing high-purity H-2 production. However, the lack of energy-efficient pathway with high CO2 capture performance sorbents hinders its development. Herein, we prepare lithium-based absorbent particles with porous micromorphologies and large surface areas using various Li-precursors, alkali metal dopants, and particle sizes, achieving fast CO2 sorption-desorption kinetics, high absorption capacity of 0.30 g CO2 g(-1) Li4SiO4, and excellent cyclic stability at a low CO2 concentration (10 vol%). Absorbent paritcles measuring 1 mm, using lithium carbonate as Li-precursor and doped with 20 mol% potassium, demonstrated a high CO2 conversion of 63.7% and a crushing mechanical strength of 25 N over 200 isothermal sorption-desorption cycles. In addition, the enhancement of absorbent particles for CL-SMR was evaluated in a fixed-bed reactor. Mechanical mixed with nickel-based oxygen carriers, lithium-based absorbent carbonation enables the in-situ CO2 removal in CL-SMR process, along with elevated methane conversion (93.3%), hydrogen purity (92.8%), and hydrogen production rate (9.45 mL min(-1) g(-1)) in a single step, while the energy demand of calcination is reduced at mild temperatures (500-600 degrees C). The incorporation of lithium-based absorbents facilitated an alternative reforming mechanism, yielding a notable 15.2% reduction in the apparent activation energy. In-situ DRIFTs experiments, combined with XRD and XPS characterization, further revealed that lithium ions in the absorbent interact with CO2 to form lithium carbonate. This process facilitates in-situ decarbonization, promotes the water-gas shift reaction, and enhances the production of high-purity hydrogen.

alpha-Olefins are essential chemical raw materials in the synthesis of emulsifiers, plasticizers, and other value-added chemicals, and ethylene oligomerization is the main method used for preparing alpha-olefins. However, catalysts employed in ethylene oligomerization have drawbacks such as poor selection of target products, catalyst particle aggregation, and deactivation. To prevent the aggregation of the catalyst and expose a large number of active sites, we propose an anchoring strategy to stabilize and uniformly disperse catalysts on multi-walled carbon nanotubes (MWCNTs). Hybrid catalysts (SCn@MWCNTs) fabricated using the strategy exhibited considerably higher catalytic performance compared with homogeneous Schiff base nickel catalysts (SCn) owing to the combined effects of MWCNTs and active nickel centers. Under optimal catalytic conditions (temperature: 25 degrees C; Al/Ni molar ratio: 500 (SCn); Al/Ni molar ratio: 700 (SCn@MWCNTs); pressure: 0.7 MPa), the activities of SC1 and SC1@MWCNTs were 6.56 x 104 and 8.25 x 104 g/(mol Ni & sdot;h), respectively. In particular, SC1@MWCNTs showed remarkable recyclability and catalytic stability.