Search Results (101)

Sorption thermal energy storage is pivotal for enhancing renewable energy utilization and supporting the transition to carbon neutrality. Its performance hinges on the formation and dynamic evolution of the reaction zone. However, the lack of in situ, spatially resolved measurement tools has hampered a mechanistic understanding and rational design. To address this, this study presents a method for characterizing the reaction zone dynamics through high-resolution intra-reactor temperature profiling. Applying this method to a zeolite 13X packed-bed reactor, we establish, for the first time, quantitative empirical correlations between operating parameters and these intrinsic reaction zone properties. A key finding is that the stable duration and output temperature are governed by the length, propagation velocity, and exothermic area of the reaction zone, coupled with the total sorption heat. Furthermore, the effects of the four critical operational parameters, including inlet air temperature, relative humidity, airflow rate, and packing thickness, on both the reaction zone characteristics and thermal output performances were systematically investigated. By integrating these mechanistic insights, we propose a hierarchical control strategy and actionable application guidelines to tailor the thermal output on demand. Full article

Magnesium hydride (MgH₂) is a promising solid-state hydrogen storage material owing to its high hydrogen capacity and low cost, yet its practical application is limited by sluggish kinetics, high operating temperatures, and poor cycling stability. Among various catalytic approaches, Fe-based catalysts have emerged as attractive candidates due to their abundance, compositional tunability, and effective promotion of hydrogen sorption reactions in MgH₂ systems. This review critically summarizes recent progress in Fe-based catalysts for MgH₂ hydrogen storage, encompassing elemental Fe, iron oxides, Fe-based alloys, and advanced composite catalysts with nanostructured and multicomponent architectures. Mechanistic insights into catalytic enhancement are discussed, with particular emphasis on interfacial electron transfer, catalytic phase evolution, hydrogen diffusion pathways, and synergistic effects between Fe-containing species and MgH₂, supported by experimental and theoretical studies. In addition to catalytic activity, key stability challenges—including catalyst agglomeration, phase segregation, interfacial degradation, and performance decay during cycling—are analyzed in relation to structural evolution and kinetic–thermodynamic trade-offs. Finally, a roadmap for the scalable design of Fe-based catalysts is proposed, highlighting rational catalyst selection, interface engineering, and compatibility with large-scale synthesis. This review aims to bridge fundamental mechanisms with practical design considerations for developing durable and high-performance MgH₂-based hydrogen storage materials. Full article

The increasing demand for clean and sustainable energy has driven significant research into hydrogen production from biomass-derived feedstocks. Unlike the gasification route, the pyrolysis of biomass followed by steam reforming of bio-oil (SRBO) offers several advantages, including the liquid nature of bio-oil and the operation at lower temperatures, which facilitate easier transportation and storage compared to raw biomass. The conventional SRBO process faces several limitations, mainly catalyst deactivation due to significant coke formation and metallic sintering, as well as low hydrogen yield and purity. Hence, the intensified sorption-enhanced steam reforming of bio-oil (SESRBO) is a promising strategy to overcome these drawbacks, to simultaneously produce high-purity hydrogen and capture carbon dioxide in situ from the reaction media. This critical review presents an in-depth comparative analysis of conventional and intensified steam reforming of bio-oil, with a focus on associated challenges. Special attention is given to recent developments in the design of bifunctional materials (BFMs), which integrate both catalyst and sorbent into a single particle, along with process optimization focusing on key parameters, i.e., reforming temperature and steam presence. Finally, the review highlights key research gaps and future directions to overcome existing challenges in achieving cost-effective and scalable hydrogen production. Full article

Studies have shown that natural organic matter can regulate pollutant behavior through multiple pathways; however, research on the environmental behavior of veterinary antibiotics (VAs) in typical alkaline calcareous loess soil under the influence of exogenous organic matter remains limited. This study investigated the influence of humic acid (HA), as a representative of natural organic matter, on the sorption behavior of ciprofloxacin (CIP) in sierozem—a typical alkaline calcareous loess soil. Using the batch equilibrium method, we examined how HA affects CIP sorption under various environmental conditions to better understand the environmental fate of VAs in soil–water systems with low organic matrix content. Results showed that CIP sorption onto sierozem involved both fast and slow processes, reaching equilibrium within 2 h, with sorption capacity increasing as HA concentration increased. Kinetic data were well described by the pseudo-second-order model regardless of HA addition, suggesting multiple mechanisms governing CIP sorption, such as chemical sorption reaction, intraparticle diffusion, film diffusion, etc. Sorption decreased with increasing temperature both before and after HA amendment, indicating an exothermic process. Isotherm analysis revealed that both the Linear and Freundlich models provided excellent fits (R² ≈ 1), implying multilayer sorption dominated by hydrophobic distribution. In ion effect experiments, cations at concentrations above 0.05 mol/L consistently inhibited CIP sorption, with inhibition strength following the order: Mg²⁺ > K⁺ > Ca²⁺ > NH₄⁺, and intensifying with increasing ionic strength. However, HA addition significantly mitigated this inhibition, likely due to complexation between HA’s functional groups (e.g., carboxyl and hydroxyl) and cations, which reduced their competitive effect and enhanced CIP sorption. pH-dependent experiments indicated stronger CIP sorption under acidic conditions. HA addition increased soil acidity, further promoting CIP retention. In summary, HA enhances CIP sorption in sierozem by providing additional sorption sites and modifying soil surface properties. These findings improve our understanding of how exogenous organic matter influences the behavior of emerging contaminants such as antibiotics in soil–water systems, offering valuable insights for environmental risk assessment in semi-arid agricultural regions. Full article

The industrial application of CO₂ methanation in Power-to-X (P2X) systems requires the development of highly active catalysts capable of operating at milder temperatures to ensure energy efficiency, while exhibiting high activity, stability and selectivity. This study reports the synthesis and optimization of Ni-based catalysts on Al₂O₃ supports, guided by a Design of Experiments (DoE, 2⁴ factorial design) approach. Initial optimization afforded a robust catalyst achieving 80% CO₂ conversion and >99% CH₄ selectivity at 325 °C. Remarkably, the incorporation of CeO₂ traces to the Ni-based catalyst substantially boosted catalytic activity, enabling higher conversions at temperatures up to 75 °C lower than the unpromoted catalyst. This improvement is attributed to Ni–CeO_x synergy, which facilitates CO₂ activation and Ni reducibility. Both formulations exhibited exceptional long-term stability over 100 h. Furthermore, process intensification via the Sorption-Enhanced Reaction Process (SERP) with the Ni-based catalyst demonstrated even superior efficiency, rapidly increasing CO₂ conversion beyond 95% with the same selectivity range. Our findings establish a clear and consistent pathway for industrial CO₂ valorization through next-generation P2X technology for high-purity synthetic natural gas (SNG) production. This process offers an efficient and sustainable route toward industrial defossilization by converting captured CO₂ and green H₂ into SNG that is readily usable within the existing energy infrastructure. Full article

The appropriate selection of renovation plaster properties is essential for ensuring the durability and effectiveness of conservation works. This study focused on the design and characterization of cement-based renovation mortars modified with synthetic zeolites with different Si/Al ratios. It was assumed that high-silica zeolites would provide more favorable mechanical and hygric performance than low-silica types. Owing to their porous structure and pozzolanic reactivity, zeolites proved to be effective additives, enhancing both the microstructure and functionality of the mortars. The modified mixtures exhibited increased total porosity, higher capillary absorption, and improved moisture transport compared with the reference mortar based on CEM I 52.5R. Dynamic vapor sorption tests confirmed that the zeolite-containing mortars achieved Moisture Buffer Values (MBV) above 2.0 g/m², which corresponds to the “excellent” moisture buffering class. Electrical resistivity measurements further demonstrated the relationship between denser microstructure and enhanced durability. At the frequency of 10 kHz, the electrical resistivity of the reference mortar reached 43,858 Ω·m, while mortars with 15% ZSM-5 and 15% Na-A achieved 62,110 Ω·m and 21,737 Ω·m. These results show that the addition of high-silica zeolite promotes the formation of a denser and more insulating matrix, highlighting the potential of this method for non-destructive quality assessment. The best overall performance was observed in mortars containing the high-silica zeolite ZSM-5. A 35% replacement of cement with ZSM-5 increased compressive strength by 10.5% compared with the reference mortar R (4.3 MPa). Frost resistance tests showed minimal mass loss (0.03% at 15% and 1.79% at 35% replacement), and ZSM-5 mortars also maintained integrity under salt crystallization. These improvements were attributed to the reaction of reactive SiO₂ and Al₂O₃ from the zeolites with Ca(OH)₂, leading to the formation of additional C-S-H. A higher Si/Al ratio promoted a denser, fibrous C-S-H morphology, as confirmed by SEM, which explains the improved strength and durability of mortars modified with ZSM-5. Full article

Thermochemical energy storage (TCES) has gained significant attention as a high-capacity, long-duration solution for renewable energy integration, yet material-level challenges hinder its widespread adoption. This review for the first time systematically examines recent advancements in nano-engineered composite thermochemical materials (TCMs), focusing on their ability to overcome intrinsic limitations of conventional systems. Sorption-based TCMs, especially salt hydrates, benefit from nano-engineering through carbon-based additives like CNTs and graphene, which enhance thermal conductivity and reaction kinetics while achieving volumetric energy densities exceeding 200 kWh/m³. For reversible reaction-based systems operating at higher temperatures (250–1000 °C), the strategies include (1) nanoparticle doping (e.g., SiO₂, Al₂O₃, carbonaceous materials) for the mitigation of sintering and agglomeration; (2) flow-improving agents to enhance fluidization; and (3) nanosized structure engineering for an enlarged specific surface area. All these approaches show promising results to address the critical issues of sintering and agglomeration, slow kinetics, and poor cyclic stability for reversible reaction-based TCMs. While laboratory results are promising, challenges still persist in side reactions, scalability, cost reduction, and system integration. In general, while nano-engineered thermochemical materials (TCMs) demonstrate transformative potential for performance enhancement, significant research and development efforts remain imperative to bridge the gap between laboratory-scale achievements and industrial implementation. Full article

In this work, Aspen Plus was used to simulate a sorption-enhanced steam methane reforming (SE-SMR) process in a fluidized bed reformer using a Ni-based catalyst and CaO as a sorbent for CO₂ removal from the reaction environment. The performances of the process in terms of the outlet gas hydrogen purity (y_H2), methane conversion (X_CH4), and hydrogen yield (η_H2) were investigated. The process was simulated by varying the following different reformer operating parameters: pressure, temperature, steam/methane (S/C) feed ratio, and CaO/CH₄ feed ratio. A clear sorption-enhanced effect occurred, where CaO was fed to the reformer, compared with traditional SMR, resulting in improvements of y_H2, X_CH4, and η_H2. This effect, in percentage terms, was more relevant, as expected, in conditions where the traditional process was unfavorable at higher pressures. The presence of CaO could only partially balance the negative effect of a pressure increase. This partial compensation of the negative pressure effect demonstrated that the intensification process has the potential to produce blue hydrogen while allowing for less severe operating conditions. Indeed, when moving traditional SMR from 1 to 10 bar, an average decrease of y_H2, X, and η by −16%, −44%, and −41%, respectively, was recorded, while when moving from 1 bar SMR to 10 bar SE-SMR, y_H2 showed an increase of +20%, while X_CH4 and η_H2 still showed a decrease of −14% and −4%. Full article

Liquid fuels obtained from CO₂ and green hydrogen (i.e., e-fuels) are powerful tools for decarbonizing economy. Improvements provided by Process Intensification in the existing conventional reactors aim to decrease energy consumption, increase yield, and ensure more compact and safe processes. This review describes the advances in the production of methanol, dimethyl ether, and hydrocarbons by Fischer–Tropsch using different Process Intensification tools, mainly membrane reactors, sorption-enhanced reactors, and structured reactors. Due to the environmental interest, this review article focused on discussing methanol and dimethyl ether synthesis from CO₂ + H₂, which also represented the most innovative approach. The use of syngas (CO + H₂) is generally preferred for the Fischer–Tropsch process; hence, studies examining this process were included in the present review. Both mathematical models and experimental results are discussed. Achievements in the improvement of catalytic reactor performance are described. Experimental results in membrane reactors show increased performance in e-fuels production compared to the conventional packed bed reactor. The combination of sorption and reaction also increases the single-pass conversion and yield, although this improvement is limited by the saturation capacity of the sorbent in most cases. Full article

Sorption-enhanced reverse water–gas shift (SE-RWGS), designated as COMAX, was studied using a Pt4A bifunctional catalyst (reactive adsorbent). The bifunctional Pt4A catalyst integrates CO₂ activation and reaction with water adsorption functionality, where the active phase is loaded onto a carrier that provides a surface area for Pt dispersion as well as H₂O adsorption capacity. The 0.3 wt% Pt-4A molecular sieve reactive sorbent was tested at a kg scale in a pressure swing (reactive) adsorption–regeneration process. More than 400 cycles over 50 days of operation were successfully demonstrated without significant decay. Cyclic stability was achieved, provided that the regeneration temperature was sufficiently high to ensure near-complete dehydration. The single-bead structure withstood the pressure swing operation effectively, with only a maximum of 2% of the total recovered reactive sorbent turning to fines (<500 μm). The successful integration of catalytic activity and water adsorption capacity into a single particle presents opportunities for the further intensification of sorption-enhanced reactions for CO₂ conversion. Full article

This study explores the impact of pore volume distribution on the structural, thermal, and mechanical properties of spinodal phase-separated silica gels synthesized with poly(ethylene oxide) as a phase-separating agent. By systematically varying gelation temperatures between 20 and 60 °C, we investigate how reaction kinetics influence the resulting pore architecture, thermal conductivity, and elasticity. Nitrogen sorption, mercury intrusion porosimetry, and SEM analysis reveal a transformation from a bimodal pore structure at low temperatures, featuring interconnected macropores, to a predominantly mesoporous network with loss of bimodality. This shift in the diameter of the macropores significantly impacts the thermal insulation properties of the gels as thermal conductivity decreases from 68 to 27 mW (m·K)⁻¹ due to reduced macroporosity, enhanced mesoporosity, and the Knudsen effect. Mechanical testing revealed a substantial decline in Young’s modulus with increasing gelation temperature. These changes are attributed to the interplay of mesoscale structural differences and density variations, driven by increasing gelation temperatures. While higher temperatures lead to reduced strut thickness and the loss of interconnected macropores, the substantial decline in Young’s modulus highlights the critical role of mesoscale structural integrity in maintaining mechanical stability. The findings underscore the importance of an optimized pore volume distribution in tailoring pore structure and performance characteristics, providing a pathway for optimizing silica gels for applications in thermal insulation, filtration, and catalysis. Full article

As a cost-effective sorbent, modified biochar has received increasing attention for the removal of heavy metal contaminants. Among several chemical modification methods, introducing thiol functional groups onto the surface of biochar has been identified as an effective enhancement approach for the heavy metal sorption and removal capacity of this porous adsorbent material. In general, chemical impregnation is a widely used method to graft thiol groups onto the surface of carbon-based materials. However, limited comparative data are available on the efficacy of the present biochar thiolation methods. In this study, the biochar of nine different organic sources was modified by two frequently used agents with distinct thiolation mechanisms: 3-Mercaptopropyltrimethoxysilane (3-MPTS) and β-mercaptoethanol. In addition to chemical impregnation, the ball milling method, a simple and environmentally friendly alternative thiolation method, was also evaluated. A comprehensive structural characterization of the biochar samples was completed before and after thiolation. A higher concentration of sulfur on the surface of the biochar was achieved through thiolation with β-mercaptoethanol, in which the thiolation mechanism is performed through an esterification reaction with the carboxylic acid functional groups of the activated biochar. Chemical impregnation was found to be a more effective thiolating method than ball milling using the same thiolating agent. Full article

With the rapid growth of the sauce-flavored liquor industry, the treatment of wastewater has become an increasingly critical challenge. This study seeks to assess the catalytic oxidation efficacy of Mn₂Cu₂O_x/Al₂O₃ catalysts in the degradation of organic pollutants present in sauce-flavored liquor wastewater, while also elucidating the mechanisms underpinning their performance. Mn₂Cu₂O_x/Al₂O₃ catalysts were synthesized, and their physicochemical properties were thoroughly characterized using advanced techniques such as Brunauer–Emmett–Teller (BET) analysis, N₂ sorption isotherm analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Moreover, the key active species involved in the catalytic oxidation process, including hydroxyl radicals (•OH) and superoxide anion radicals (•O₂⁻), were identified through hydroxyl radical quenching experiments employing tertiary butyl alcohol (TBA). The contribution of these free radicals to enhancing the ozone catalytic oxidation performance was also systematically evaluated. Based on both experimental data and theoretical analyses, the Mn₂Cu₂O_x/Al₂O₃ catalysts demonstrate remarkable catalytic activity and stability, significantly reducing chemical oxygen demand (COD) levels in wastewater. Furthermore, the catalysts are capable of activating oxygen molecules (O₂) during the reaction, producing reactive oxygen species, such as •O₂⁻ and •OH, which are potent oxidizing agents that effectively decompose organic pollutants in wastewater. The proposed catalysts represent a highly promising solution for the treatment of sauce-flavored liquor wastewater and lays a solid foundation for its future industrial application. Full article

Metal hydride-based hydrogen storage (MHHS) has been used for several purposes, including mobile and stationary applications. In general, the overall MHHS performance for both applications depends on three main factors, which are the appropriate selection of metal hydride material uses, design configurations of the MHHS based on the heat exchanger, and overall operating conditions. However, there are different specific requirements for the two applications. The weight of the overall MHHS is the key requirement for mobile applications, while hydrogen storage capacity is the key requirement for stationary applications. Based on these requirements, several techniques have been recently used to enhance MHHS performance by mostly considering the faster hydrogen absorption/desorption reaction. Considering metal hydride (MH) materials, their low thermal conductivity significantly impacts the hydrogen absorption/desorption reaction. For this purpose, a comprehensive understanding of these three main factors and the hydrogen absorption/desorption reaction is critical and it should be up to date to obtain the suitable MHHS performance for all related applications. Therefore, this article reviews the key techniques, which have recently been applied for the enhancement of MHHS performance. In the review, it is demonstrated that the design and layout of the heat exchanger greatly affect the performance of the internal heat exchanger. The initial temperature of the heat transfer fluid and hydrogen supply pressure are the main parameters to increase the hydrogen sorption rate and specific heating power. The higher supply pressure results in the improvement in specific heating power. For the metal hydride material selection under the consideration of mobile applications and stationary applications, it is important to strike trade-offs between hydrogen storage capacity, weight, material cost, and effective thermal conductivity. Full article

The batch sorption process is used to remove various species from wastewater and can be optimised by selecting adequate process parameters and reactor geometry. As sorption is a heterogeneous process, achieving the desired process outcomes in a batch reactor relies heavily on establishing conditions in which the influence of interphase diffusion is minimised while keeping the efficiency and cost of the process at acceptable values. These conditions can be managed by the selection of appropriate reactor geometries and mixing speed through examination of their influence on the sorption yield and cost. The relationship between mixing speed and power consumption is important, as excessive mixing can lead to increased energy costs without proportional gains in sorption kinetics and efficiency. For these reasons, the effect of reactor geometry and mixing speed on copper sorption kinetics, efficiency, and energy consumption was studied. The Ritchie model and Mixed surface reaction and diffusion-controlled sorption kinetic model were employed for the kinetic study. CFD simulations were carried out to identify optimal designs that enhance process efficiency and reduce energy consumption. Data obtained indicate that the sorption process generally follows second-order kinetics. Results demonstrate that sorption can be effectively conducted at impeller speeds lower than the critical suspension speed (N_JS), achieving almost equal removal efficiencies (after 30 min) while reducing energy consumption. From the perspective of energy consumption, reactors without baffles are a significantly better solution than baffled reactors, especially when using a PBT impeller. From a kinetic standpoint, better results are achieved at the highest N/N_JS or N_JS. In baffled reactors, considering both power consumption and process duration, the SBT impeller emerges as the most efficient choice. Considering the compromises between power consumption and process duration the choice of reactor geometry and specific operating conditions should align with process priorities, such as energy savings through lower power consumption or reduced mixing time. FTIR spectra did not reveal the differences in the zeolite structure after the sorption process occurred. Full article