Phase change absorbents are promising for large-scale CO2 capture due to their low energy consumption of regeneration. However, the variations in solvent viscosity and density, coupled with unpredictable phase separation timing, lead to an unpredictable absorption rate and hinder further reactor development. This study investigates the classic phase separation systems, MEA-physical solvent-H2O, to clarify the effect of the viscosity and density changes on phase-splitting behavior and kinetics during CO2 absorption. Absorption kinetics of three typical phase-splitting behavior systems, MEA-sulfolane-H2O (homogeneous throughout absorption), MEA-1-butanol-H2O (separation at mid-stage absorption), and MEA-1-octanol-H2O (separation at early-stage absorption) were evaluated. The results show that the interphase density difference is a key parameter determining whether a stable liquid-liquid interface can be maintained during absorption. When Delta rho exceeds approximately 0.18 g/mL, a stable liquid-liquid phase layer can be observed during absorption. The increasing viscosity gradually hinders the diffusion of CO2 in the liquid phase and changes kinetic patterns during CO2 absorption. All systems are controlled by mass transfer process in the homogeneous state at the initial absorption stage. As reaction proceeds, the kinetic control switches to combined control of mass transfer-reaction, where rates correlate with bulk solution viscosity. However, after phase separation appears, the absorption process becomes dominated by mass transfer control again, with the kinetics correlating with lean phase viscosity. Notably, the early-phase-separation system exhibits no combined control stage. To quantitatively account for this behavior, a power-law viscosity correction term was verified to be effective to modify the macroscopic kinetic models, and the reaction kinetics equations of three phase transition systems were obtained.

[Purposes]Oxidative degradation of alkanolamine absorbents significantly limits the economical viability of CO2 capture process.A detailed investigation into oxidative degradation behav-ior of alkanolamines with different molecular structures is crucial for the screen of highly stable absor-bents,the optimization of process parameter,and the elucidation of degradation mechanisms.[Meth-ods]In this study,the oxidative degradation characteristics of 13 CO2-loading alkanolamines were systematically examined under conditions of 120 ℃ and 1.0 MPa with O2.[Results]The experimental results reveal that the steric hindrance effect in the alkanolamine molecular structure is a key factor in-fluencing oxidative stability.Notably,N,N-dimethylethanolamine and 2-amino-2-methyl-1-propa-nol exhibit superior oxidative stability(with amine loss ratios of 9.5%and 2%after 8 h degradation,respectively)owing to the strong steric hindrance around their amino groups,significantly lower than the 26.2%loss for monoethanolamine.The oxidation degradation process reduces the alkalinity of the system,and the degree of alkalinity loss is basically the same as that of amine loss.The pH of the so-lutions generally decreases by 1%-7%,viscosity decreases by 0.6%-16%,conductivity increases sig-nificantly,and surface tension declines.These physicochemical changes are primarily attributed to the accumulation of organic acids and the cleavage of alkanolamine molecular chains.Furthermore,for-mate and oxalate are detected in all degraded alkanolamine solutions,while acetate formation is strongly correlated with the presence of ethyl side chains in the molecular structure.In addition,dur-ing the oxidative degradation of primary alkanolamine at high temperatures,its primary oxidation prod-ucts undergo further intermolecular condensation reactions to generate more complex secondary degra-dation products.

Electrochemically mediated amine regeneration (EMAR) is a promising CO2 capture technology. However, the slow desorption kinetics of EMAR results in high energy consumption. In this work, we propose a novel approach to enhance EMAR by magnetohydrodynamics (MHD). Using ethylenediamine (EDA) as the absorbent, the introduction of a magnetic field in EMAR facilitates the desorption process by enhancing mass transfer. Mechanistic analysis indicates that the applied magnetic field induces localized electrolyte flow via the MHD effect. This flow disrupts the stagnant diffusion layer, thereby accelerating reactants transfer to the electrode surface. The energy consumption of desorption process for the MHD enhanced EMAR is 42.6 kJ & centerdot;mol(-1) CO2 (similar to 0.968 GJ & centerdot;t(-1) CO2) at 100 A & centerdot;m(-2), representing an 18.3% reduction compared to the baseline EDA system. This work provides new insights into advancing EMAR technology from the mass transfer perspective

Abstract Amine-functionalized solid adsorbents are widely considered promising candidates for direct air capture because of their high CO2 selectivity with good regenerability. However, under DAC-relevant low-CO2 conditions, the coupled effects of temperature and inlet CO2 concentration on equilibrium, kinetics, and dynamic fixed-bed performance remain insufficiently understood. In this work, 50 wt % TEPA/SBA-15 was prepared by wet impregnation and systematically evaluated under 0.04–0.20 vol % CO2 to clarify the thermodynamic-kinetic coupling governing adsorption behavior. The equilibrium data were better described by the Freundlich model than by the Langmuir model (R2 > 0.99), indicating a heterogeneous adsorption surface, while the Avrami fractional-order model gave the best fit to the kinetic data. The apparent rate constant increased strongly with CO2 concentration and slightly with temperature. Breakthrough experiments further showed that higher inlet CO2 concentration shortened the breakthrough time, whereas higher temperature advanced breakthrough but also sharpened the breakthrough front. Analysis of the length of unused bed showed that fixed-bed utilization was controlled by the competition between thermodynamic loss and kinetic enhancement. At 0.08–0.20 vol % CO2, heating generally reduced LUB/L and improved bed utilization, whereas at 0.04 vol % CO2 the temperature effect became nonmonotonic. These results demonstrate that fixed-bed performance under low-CO2 conditions should be evaluated from both breakthrough behavior and bed utilization, and provide a basis for DAC-oriented adsorbent assessment and process design.

Aqueous amine solutions used for electrochemical CO2 capture typically exhibit low conductivity, and therefore require supporting electrolytes. However, the ionic properties of supporting electrolytes vary considerably, which may influence electrode processes and system stability. In this work, commonly used supporting electrolytes (MCl, MNO3, and M2SO4, where M = Na+, K+) were selected, and their effects on the CO2 absorption behavior, electrochemical activity and stability, corrosion characteristics and amine stability were systematically evaluated in a representative copper-ethanolamine (Cu-MEA) system. The results show that supporting electrolytes (similar to 0.5 M) primarily affect the electrochemical process and system stability, rather than the CO2 absorption behavior. In particular, cations improve ionic transport and lower charge-transfer resistance, whereas anions determine corrosion behavior and system stability. Among the supporting electrolytes, KNO3 provided a favorable balance between electrode kinetics and system stability. Further optimization reveals that increasing the KNO3 concentration to 0.5 M achieves optimal electrochemical performance. These findings provide a reference for selecting supporting electrolytes in amine-based electrochemical CO2 capture systems.

Phosphogypsum (PG) is a massive solid waste byproduct during the wet-process phosphoric acid production, with a global stockpile exceeding 6 billion tons and a comprehensive utilization rate of less than 25%. Existing PG-based CO2 mineralization technologies primarily produce low-value calcite-phase CaCO3, limiting the economic viability of this approach. To achieve the controllable preparation of aragonite, which is of greater economic value, this work systematically investigated the influences of various processing parameters on the crystal structure of the obtained CaCO3. According to the comparative experiments of one-step and two-step direct mineralization processes, it was found that, under optimized conditions (70 degrees C, Mg2+ concentration of 5.00 & times; 10-3 mol/L, CO2 flow rate of 400 mL/min, and stirring speed of 250 rpm), the one-step mineralization process enables the direct synthesis of aragonite whiskers with an aspect ratio of up to 10:1, a product purity exceeding 95% and a PG conversion ratio over 99%. In contrast, the two-step mineralization method failed to produce aragonite due to the excessively high supersaturation. Furthermore, the study revealed that the aragonite formation follows a four-stage mechanism: CO2 absorption-dominant nucleation-multiphase coexistence-crystal phase transformation. This work not only achieved the controllable synthesis of aragonite, but also elucidated its formation mechanism, providing an efficient and feasible pathway for PG resource utilization and CO2 reduction.

Phase-change solvents (PCSs) integrated with energy-efficient processes offer a promising pathway toward lowenergy CO2 capture. Conventional solvent development often proceeds independently of process design, limiting further reduction of energy consumption and cost. An Integrated Solvent Selection-Process Design Methodology proposed in this work enables the design of suitable solvent systems for process. It incorporates the SolventTechnology Matching Method (STMM) to generate potential operational states of the different solvent-process systems. And a techno-economic evaluation function evaluating investment and operating costs is introduced to systematically analysis solvent-process systems compatibility based on extensive solvent-operational states prior to factory implementation. The compatibility of Near-Isothermal CO2 Capture Technology with PhaseChange Solvents (NI-PCSs-TCC) and five solvents is evaluated. Optimal solvents for NI-PCSs-TCC should exhibit: (i) a CO2-lean phase ratio > 40 %, (ii) high absorption capacity (>0.4 mol CO2/mol amine at 343.15 K), and (iii) efficient desorption (<0.2 mol CO2/mol amine at 373.15 K). Economic analysis reveals the costreduction potentials: while solvent development yields marginal gains (similar to 10 % cost reduction), process optimization demonstrates substantially higher efficacy (10 similar to 40 % cost reduction). DEA/sulfolane/H2O system achieves best process compatibility among the solvents. Solvents with superior process compatibility demonstrate greater potential of cost reduction for CO2 capture.

Cu is one of the most widely used catalysts in the electrochemical CO2 reduction reaction (CO2RR) due to its unique ability to convert CO2 to C2+ products. However, surface reconstruction of Cu significantly affects the activity and stability of Cu catalyst. In this work, density functional theory (DFT) coupled with implicit solvation ab initio molecular dynamics (AIMD) was employed to unveil the possible migration pathways of surface Cu atoms during the structural evolution processes under CO2RR. Surface energy, as the intrinsic thermodynamic driving force of surface reconstruction, is distributed to individual surface Cu atoms and shows a quasi-linear relationship with their generalized coordination number (GCN), demonstrating a maximum driving force of ∼1.10 eV under the applied electric field. The *CO adsorbate weakens the binding of surface Cu atoms, resulting in a maximum vertical displacement of Cu atoms of up to 0.8 Å. In contrast, *H on Cu(100) at high coverage induces a horizontal extruding effect on the surface Cu atoms, causing them to move up to 2 Å. The observable migration of surface Cu atoms in the AIMD run occurs only on Cu adatoms, with the adsorption of pure *H or coadsorption of *CO and *H.

Sustainable aviation fuels (SAFs) are being considered as alternative, clean, sustainable, and renewable energy resources to meet the global carbon-neutral target. Currently, most SAFs are blended with conventional fuels, which alters the composition and properties of aviation fuels, but a limited understanding of the hydrocarbon mixture composition and properties hinders their development. Quantitative structure-property relationship (QSPR) models predict macroscopic properties based on molecular structures, but existing models mainly address pure substances, leaving descriptor generation for mixtures challenging. This study introduces characteristic triangles, derived from four key oil features (average carbon number, aromatics, cycloalkanes, and isomeric alkanes), to predict hydrocarbon mixture properties (density, kinematic viscosity, refractive index, surface tension, average volume boiling point, flash point, and freezing point). Results show that integrating triangular descriptors significantly enhances predictive accuracy, enabling rapid property evaluation and offering valuable design insights for new oil products.

Chemical looping hydrogen generation (CLHG), based on the redox cycle of oxygen carriers, enables the conversion of low-grade reducing gases (e.g., blast furnace gas-BFG) into high-purity hydrogen, representing a costeffective and high-efficiency hydrogen production technology. The multistep redox kinetics of oxygen carrier is crucial for the reactor design and numerical simulation. In this study the kinetic behaviors of iron-based oxygen carriers (ZC-CFO) during BFG reduction, steam oxidation (hydrogen production), and oxygen regeneration process were investigated by utilizing thermogravimetric analysis and fixed-bed reactor isothermal experiments. With an "activation energy variation-reaction rate deconvolution method", the reduction process was decoupled into three distinct reaction stages: CuFe2O4-* Cu + Fe3O4, Fe3O4-* FeO, and FeO-* Fe. The reduction activation energies derived from JMA (Johnson-Mehl-Avrami) model fitting (18.90 kJ mol-1, 23.89 kJ mol-1, 33.73 kJ mol-1) aligned well with model-free method results, validating the accuracy of the proposed approach. The steam oxidation process followed a two-stage reaction pathway: Fe-* FeO and FeO-* Fe3O4, while the lattice oxygen regeneration process exhibited a rapid single-step reaction. Compared to the reduction process, the oxidation process showed lower activation energies, which was 14.69 kJ mol-1 and 19.87 kJ mol-1 for the twostep steam oxidation stage, and 13.47 kJ mol-1 for the oxygen regeneration stage. Furthermore, the effects of reaction temperature and gas concentration were systematically investigated, ultimately establishing a comprehensive redox kinetic model.

Sulfur dioxide (SO 2 ) is a common air pollutant, primarily emitted from fossil fuel combustion and industrial flue gas. Deep eutectic solvents (DESs) have been proven to be innovative, sustainable SO 2 absorbents. Meanwhile, the relationships between DESs molecules and their SO 2 capacity or SO 2 absorption selectivity in the gas source containing carbon dioxide (CO 2 ) are unclear. In this work, a multilayer perceptron (MLP) model was developed to predict the SO 2 capacity of DESs based on the database containing 1382 SO 2 capacity data from the literature. The SO 2 capacity with respect to the chemical and physical absorption was investigated. The optimal MLP model (R 2 (coefficient of determination) = 0.9924, MSE (mean square error) = 0.0009) with 13 input descriptors including COSMO-RS (Conductor-like Screening Model for Realistic Solvents) theory descriptors and temperature, pressure, and water concentration validated its superior predictive capability in forecasting both physical and chemical absorption. From the SHAP (Shapley Additive Explanations) analysis, the DESs candidates with high SO 2 capacity should consider anionic and relatively long-branched components. A database containing 924 novel DESs was constructed. Through the integration of this model with a predictive model for CO 2 capacity, the promising candidates with high selectivity of SO 2 , such as [N444]Cl (tetrabutylammonium chloride) and 2-Mim (2-methylimidazole), were effectively identified within the novel database. This work offers insights for screening suitable DESs for the flue gas desulphurization (FGD) process.

Chemical looping hydrogen generation (CLHG) is a clean method for producing high-purity H2 from lowconcentration reductive gases via redox cycles of oxygen carriers (OCs). A key challenge in CLHG is carbon deposition, which leads to OCs deactivation and reduced efficiency. This study aimed to investigate carbon deposition mechanisms, release behavior, and its control strategies. Results indicated that the iron-based OCs was reduced in a CO/CO2 mixed atmosphere following the routine of Fe(III) -> Fe(II) -> Fe0, where Fe0 catalyzed Fe3C and C deposition at moderate temperatures. By increasing the reduction temperature and CO2 partial pressure, carbon deposition reduced significantly. During hydrogen production stage, Fe3C converted to Fe3O4 and CO2, impairing both H2 purity and steam oxidation rate. Furthermore, carbon deposition also impaired OCs' cycling stability, but air-regeneration effectively restored reactivity by eliminating carbon. This study provides valuable insights into the reaction mechanism and process optimization of CLHG.

In this study, the property prediction models for density, surface tension, kinematic viscosity, dynamic viscosity, and flash point of diesel were developed by the feedforward neural network method utilizing the fuel distillation curve (T10-T90) as light and heavy composition distribution characteristics and the refractive index as the average composition characteristic. The applicability of the method across hydrocarbon mixtures of diesel and gasoline-kerosene-diesel fractions was explored. 92 surrogate diesel samples, ranging from binary to septenary mixtures, were prepared, and their refractive index, distillation curve, density, flash point, and surface tension were measured. The property prediction models were developed using 100 gasoline-kerosene and 92 diesel fraction samples. According to SHAP value analysis, the density of diesel is determined by the refractive index, while the flash point, surface tension, and viscosity depend on the light component (T10), the refractive index and the middle boiling component (T50), and both light and middle boiling components (T30-T50), respectively. The determinants of density and flash point of gasoline-kerosene-diesel fraction fuel are consistent with the model of diesel fraction. The secondary influencing factor of surface tension shifts to lighter composition (from T50 to T10), and the factors influencing viscosity are more complex, as it is affected by the middle boiling component.

To address the issues of reliance on external activator in conventional biomass-derived activated carbon preparation and the requirement for pre-pulverization of feedstock, this study developed a coupled hydrothermal carbonization - pyrolysis self-activation process. Hydrothermal treatment was employed to produce a homogenized, carbon-enriched precursor. The endogenous H2O within this precursor and the CO2 generated during pyrolysis served as activators, achieving self-activation of the carbon matrix. Following process optimization using response surface methodology, the resulting bamboo activated carbon exhibited a carbon yield of 13.1 % and a specific surface area of 1556 m2 center dot g-1. Under conditions of 25 degrees C and 648.1 Pa, its equilibrium benzene adsorption capacity reached 141.6 mL center dot g-1. The adsorption process was identified to be spontaneous, exothermic, and physically driven. This process provides a novel, green approach for the fabrication of biomass-derived activated carbon, demonstrating significant potential for industrial applications.

Understanding the underlying relationship between the oil composition and properties and predicting the properties of kerosene and gasoline are crucial for its application. Density, viscosity, surface tension, freezing point, viscosity, and flash point are fundamental physical properties, but their relationships with compositional characteristics remain unclear. In this work, artificial neural networks and Shapley additive explanation analysis are applied to link the six properties with the distillation curve and refractive index, which describe the heavy, light, and average oil composition characteristics. The most important features for the density, viscosity, surface tension, flash point, and freezing point are the refractive index, 10% boiling temperature, 70% boiling temperature, initial boiling temperature, and 50% boiling temperature, respectively. Linear regression fits the density, viscosity, and flash point, while nonlinear regression fits the surface tension and freezing point. This article establishes rapid prediction models for these properties and provides a reference for revising the mixing rules and improving fuel properties.

The adsorption behavior of Dimethyl methylphosphonate (DMMP), as a simulant of sarin nerve agent, especially in the presence of water vapor, is crucial for the design of efficient chemical protection equipment. Experimental results reveal DMMP ' s adsorption isotherm on granular activated carbon (GAC) as a typical type I. The adsorption process was a spontaneous and exothermic physical adsorption process, and the adsorption mechanism was in accordance with Dubinin ' s micropore filling theory. In the relative humidity range of 10 % similar to 90 %, the isotherm remained I -type, and the effect of water vapor on the equilibrium adsorption capacity and apparent adsorption rate was weak. Molecular simulations also show that DMMP adsorption on GAC follows a type I isotherm, primarily driven by van der Waals forces of physical adsorption. The adsorption potential energy between DMMP and GAC surpasses that of water molecules, resulting in negligible effects from water vapor on DMMP adsorption equilibrium. Meanwhile, water molecules had minimal effect on the diffusion of DMMP molecules in the GAC pores, and the positional distribution of DMMP multilayer adsorption was consistent under different relative humidity conditions. Furthermore, the presence of polar functional groups such as hydroxyl groups significantly affects the adsorption equilibrium of DMMP.

Developing low-energy decarbonization technology is crucial for achieving large-scale CO2 capture from industrial flue gas. During the absorption of CO2, phase-change solvents can separate into a CO2-rich phase and a CO2-lean phase. By directing the CO2-rich phase to the desorber for regeneration, the energy consumption of traditional CO2 capture using phase-change solvents is reduced compared to homogeneous solvents. However, the heat absorbed by the CO2-lean phase remains unrecovered. In this study, a near-isothermal CO2 capture technology utilizing phase-change solvents (NI-PCSs-TCC) is proposed to recover the reaction heat from the CO2-lean phase to compensate for regeneration energy requirement through a heat pump system. A Solvent-Technology Matching Method (STMM) that optimizes solvent fomula and operating parameters simultaneously by automatically assigning parameters into process simulations. Through comprehensive evaluation of energy consumption, CO2 capture efficiency, and amine loss, the optimal operating range of solvent concentration and process parameters for NI-PCSs-TCC with MEA/sulfolane/water are determined and discussed. The energy consumption of NI-PCSs-TCC with MEA/sulfolane/water can be below 2.00 GJ/tCO2 at an absorption temperature range of 338.15~343.15 K and a desorption temperature range of 373.15~381.15 K.

Developing low-energy decarbonization technology is crucial for achieving large-scale CO2 capture from industrial flue gas. During the absorption of CO2, phase-change solvents (PCSs) can be separated into a CO2-rich phase and a CO2-lean phase. By exclusively supplying the CO2-rich phase to the desorber for solvent regeneration, the need for sensible heat is eliminated as a result of the reduction of the amount of solvent. However, the heat absorbed by the CO2-lean phase remains unrecovered. This study proposes a near-isothermal CO2 capture technology utilizing phase-change solvents (NI-PCSs-TCC) to recover the reaction heat absorbed by the CO2-lean phase to compensate for regeneration heat through a heat pump system. A Solvent-Technology Matching Method (STMM) is proposed, which helps to co-optimize the solvent concentration and process operation parameters. The optimal operating range for the MEA/sulfolane/water solvent concentration and process parameters within the NI-PCSs-TCC is evaluated. NI-PCSs-TCC can achieve an energy consumption of 2.16 GJ/t CO2 between the temperature ranges of 338.15-341.15 K for absorption and 379.15-383.15 K for desorption. This energy reduction is possible while maintaining a capture efficiency of over 90% and a lean loading of 0.2540 mol of CO2/mol of amine.

Photocatalytic oxidative dehydrogenation of ethane to ethylene with a high selectivity is an attractive reaction. In this study, different types of heterojunctions between Pd/TiO2 and a second metal oxide semiconductor were designed and synthesized to realize high activity conversion of C2H6 to C2H4. Pd/TiO2-AgO heterojunction was proved with best reaction performance. The addition of AgO facilitated the activation of reactant molecules. It enhanced directional transfer of electron-hole pairs and separation efficiency of photogenerated carriers. Pd/TiO2-5% AgO heterojunction was proved with the best separation ability of photogenerated carriers and the largest number of surface hydroxyl groups. Detailed charge transfer path and reaction mechanism were proposed and discussed.

Thermal stress is an important reason of coal particle primary fragmentation, during which the role of pore structure is ambiguous. Thermal stress induced fragmentation experiments were conducted with low volatile coal/char particles, and the results show that the fragmentation severity enhances with increasing porosity. Various porous thermal stress models were developed with finite element method, and the influences of the pore shape, size, position and porosity on the thermal stress were discussed. The maximum thermal stress inside particle increases with pore curvature, the pore position affects the thermal stress more significantly at the particle center and surface. The expectation of the maximum tensile thermal stress linearly increases with porosity, making the particles with higher porosity easier to fragment, contrary to the conclusion deduced from the devolatilization theory. The obtained results are valuable for the analysis of different thermal processes concerning the thermal stresses of the solid feedstocks.