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Journal articleZhang C, Nisar S, Liu Y, et al., 2026,
Process intensification via probe sonication in protic ionic liquid pretreatment of biomass
, Chemical Engineering Journal, Vol: 541, ISSN: 1385-8947Protic ionic liquids have proven to be feasible and cost-effective for the fractionation of lignocellulosic biomass into renewable fuels and materials (the ionoSolv process). This study tested probe sonication as a process accelerator for the ionoSolv pretreatment of Miscanthus × giganteus (grass) and spruce (softwood) using the low-cost PIL, N,N-dimethylbutylammonium hydrogen sulfate ([DMBA][HSO<inf>4</inf>], 20 wt% water content). Treatments were run at moderate temperatures (110 and 130 °C for Miscanthus; 130 and 150 °C for spruce). Results showed that sonication greatly improved softwood pretreatment, whereas its effect on grass biomass was less pronounced. At 130 °C, spruce displayed high recalcitrance to the conventional ionoSolv process, yielding only 18.1% glucose after 4 h of treatment. In contrast, with sonication, an equivalent saccharification yield was achieved after only 0.5 h of treatment, and the yield further exceeded 40% after 2 h. Monitoring the temperature profile showed that the main driver of this improvement was the temperature rise induced by sonication, rather than enhanced mass transfer. Additionally, sonication was observed to produce two pulp layers, with the upper layer having finer particles. For spruce, this upper layer was markedly more digestible than the lower layer. A preliminary techno-economic analysis indicated that applying sonication during spruce fractionation could reduce the minimum selling price of spruce-derived ethanol relative to the conventional ionoSolv route, although the magnitude of the benefit depends on the extent to which the sonication-induced, laboratory-scale temperature increase can be maintained at an industrial scale.
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Journal articleQusty H, Ata F, Fennell P, et al., 2026,
Density and carbon dioxide solubility in aqueous solutions of potassium glycinate
, Fluid Phase Equilibria, Vol: 607, ISSN: 0378-3812We report measurements of the solubility of CO<inf>2</inf> in aqueous potassium glycinate and of the density of the solution with and without CO<inf>2</inf> loading. The CO<inf>2</inf> solubility was measured with a bespoke static-synthetic vapour liquid equilibrium (VLE) apparatus, while densities were measured with a high-pressure vibrating-tube densimeter. The VLE apparatus was validated by means of measuring the solubility of CO<inf>2</inf> in a 7 mol·kg<sup>-1</sup> aqueous ethanolamine solution, and the results were in good agreement with the literature. Three molalities of aqueous potassium glycinate were studied: (1, 2 and 3) mol·kg<sup>-1</sup>. The CO<inf>2</inf> solubility measurements were made at temperatures between (313.15 and 393.15) K with pressures up to 0.65 MPa, while the density was measured at temperatures between (298.15 and 393.15) K with pressures up to 10 MPa.
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Journal articleEdwards P, Leal da Silva WR, Fennell P, et al., 2026,
Strength performance and environmental assessment of Portland clinker
, Cement and Concrete Research, Vol: 205, ISSN: 0008-8846Alite influences both the early-age strength development and environmental footprint of concrete. However, the link between the alite content in clinker, strength development in concrete, and its carbon footprint remains overlooked in life cycle assessment. We study CEM I mortars containing clinkers with 5–85 wt% alite, combining thermodynamic modelling with a compressive strength prediction model based on the combined water fraction. Our model predicts that mortars made from high alite clinkers have 29% higher 28-day compressive strengths than that of low alite clinkers, at equivalent clinker and water contents. However, higher alite clinkers increase the CO<inf>2</inf>-eq. emissions of mortars by up to 19% compared with lower alite clinkers. In general, increasing alite content in clinker reduces CO<inf>2</inf>-eq. emissions per unit of strength gained in mortar. Therefore, the carbon footprint of concrete can be reduced by optimising both the alite content in clinker and concrete mix design.
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Journal articleFerru N, Bischof M, Saporito M, et al., 2026,
Structured sorbents for direct air capture: the impact of materials and chemicals on performance
, AIChE Journal, ISSN: 0001-1541Structured sorbents can efficiently process large air volumes required for Direct Air Capture (DAC), but their broad implementation is limited by challenges in producing reproducible and homogeneous materials. This work presents a robust procedure to graft amines onto monolithic sorbents and systematically investigates how CO2 capture performance is influenced by three fundamental material building blocks: substrate type(mullite vs. cordierite), alumina loading, and amine type (APTMS vs. TRI). X-ray Computed Tomography and gravimetric analyses confirm uniform amine distribution,with CO2 adsorption capacity scaling linearly with alumina mass. From a process perspective, lower density substrates achieve higher specific CO2 uptake, thus reducing the energy demand for regeneration. Breakthrough experiments demonstrate that humiditysignificantly enhances adsorption thermodynamics and kinetics: CO2 uptake increases by 30% for APTMS and 70% for TRI, and adsorption kinetics are accelerated. This study provides quantitative material-performance relationships necessary for process design and contactor optimization.
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Conference paperChalasti E, Oluleye G, Papathanasiou MM, et al., 2026,
Temporal aggregation bias in model-based Direct Air Capture performance under weather variability
, The 36th European Symposium on Computer Aided Process Engineering, Publisher: PSE Press, Pages: 297-305, ISSN: 2818-4734<jats:p>Direct Air Capture (DAC) is a negative emissions technology whose performance is inherently linked to ambient conditions, which directly affect its primary feed stream (air). A common simplification in DAC model simulations is the use of fixed weather conditions, which can bias the predicted performance under weather variability. In response, this study quantifies the impact of local meteorological variability and temporal weather aggregation on the performance of DAC units. Building on a previously developed and validated 1D mechanistic model of a fixed-bed Steam-assisted Temperature Vacuum Swing Adsorption (S-TVSA) DAC process, we simulate its operation using weather data from the Met Office station at Buchan (UK), near the Saint Fergus terminal - a strategic hub for Carbon Capture and Storage (CCS) activities in Scotland. A two-branch methodological framework is developed combining optimization and forward simulations. Operating conditions are optimized using a multi-objective genetic algorithm (NSGA-II) to maximize productivity (Pr) and minimize specific equivalent work (Weq) at two temporal resolutions. Furthermore, daily weather inputs are aggregated on a monthly and yearly scale to assess the impact of data resolution on model predictions and real operational gains. Results show that temporal weather aggregation to yearly averages biases DAC key performance indicators, overestimating Pr by up to 5% while underestimating Weq by up to 31%, relative to performance based on daily weather variations. Moreover, optimization strategies that explicitly account for monthly weather variability present monthly gains, by increasing Pr by up to 10%. Yet, these monthly gains do not necessarily translate into significant operational performance benefits at the annual scale when daily weather data is propagated in the process model.</jats:p>
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Conference paperFennell PS, Hellgardt K, Lewin DR, 2026,
The Imperial College Integrated Design Project
, The 36th European Symposium on Computer Aided Process Engineering, Publisher: PSE Press, Pages: 2631-2637, ISSN: 2818-4734<jats:p>The Imperial College Integrated Design Project reframes the chemical engineering capstone as a structured educational journey that develops professional competence rather than simply delivering a final technical report. The programme is grounded in four pedagogical pillars—authenticity, integration, impact, and reflection—which align with the graduate attributes required by the Institution of Chemical Engineers. Authenticity is achieved through open-ended problems drawn from industrial partners and emerging research needs; integration connects knowledge from across the curriculum into a coherent systems perspective; impact emphasises user-centred, sustainable solutions; and reflection cultivates metacognitive awareness of decision making and learning from failure. A mentored-autonomy model supports student teams through weekly checkpoints, skills workshops, and access to disciplinary experts. Assessment deliberately balances artefact quality with evidence of process, rewarding reasoning under uncertainty, ethical judgement, and communication alongside technical performance. Ethics, safety, and sustainability are embedded through lifecycle analysis and HAZOP requirements rather than treated as add-ons. The four-phase structure—scoping, feasibility, detailed design, and deployment—scaffolds increasing complexity while maintaining measurable progress and accountability. A 2024 project on renewable-powered green ammonia illustrates how students integrate decision-making methods, simulation tools, and stakeholder negotiation within a realistic professional context. Educational outcomes include strengthened systems thinking, collaboration, project leadership, and the ability to justify design choices in social and environmental terms. Institutional benefits include deeper industry engagement and improved graduate readiness. The paper argues that capstones should be judged by the quality of learning processes as much as by final design
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Conference paperJaafar NS, Manaf NA, Fadzil NFEN, et al., 2026,
Synergistic integration of direct air capture in bioenergy systems
, The 36th European Symposium on Computer Aided Process Engineering, Publisher: PSE Press, Pages: 927-933, ISSN: 2818-4734<jats:p>The present work aims to demonstrate the synergy achieved through the integration of biomass gasification with a direct air capture (DAC) system to maximize overall CO2 removal capacity, while simultaneously converting waste into value-added products (hydrogen) and supplying the energy required for DAC operation (BG-H2P-DAC). The proposed configuration is modeled using Aspen Plus to investigate the synergistic interactions and key performance indicators of the BG-H2P-DAC system. Parametric analyses are conducted by varying gasification temperature, air inlet flow rate, and amine concentration and flow rate. The results indicate that increasing the monoethanolamine (MEA) concentration from 10% to 40% leads to a gradual decline in CO2 capture efficiency, accompanied by a reduction in CO2 slip. The system achieves a net specific electricity consumption of 0.0293 MWh/t CO2, confirming that the electricity generated from the integrated steam power cycle is sufficient to fully offset the electrical requirements of the DAC process. The regeneration heat requirement at a steam temperature of 150 °C is 1.32 MWh/t CO2, which represents the total net thermal demand of the DAC unit.</jats:p>
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Conference paperGlover A, Papathanasiou MM, Pini R, 2026,
Differentiable Programming for Cyclic Adsorption Processes
, The 36th European Symposium on Computer Aided Process Engineering, Publisher: PSE Press, Pages: 978-985, ISSN: 2818-4734<jats:p>The design of cyclic adsorption processes is computationally expensive as it involves screening many process designs, each of which involve a time-consuming simulation to reach cyclic steady state. In this work, we demonstrate how differentiable programming can be used to accelerate both the simulation and attainment of cyclic steady state for a four-step pressure vacuum swing adsorption (PVSA) process to concentrate carbon dioxide from flue gas. A mechanistic one-dimensional dynamic adsorption model was implemented in JAX, enabling automatic differentiation and just-in-time compilation for efficient solution and accurate sensitivity evaluation. The latter was exploited to implement a Newton-based direct determination method for accelerated convergence to cyclic steady state, avoiding repeated cycle simulations. Across 4096 designs sampled in a six-dimensional design space, the direct determination method converged in an average of 4.6 iterations, compared to 145 cycles required by successive substitution. When combined with the computational gains from the JAX framework, this resulted in an overall speed-up of over 20 times relative to the conventional MATLAB-based implementation.</jats:p>
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Journal articleAzzan H, Danaci D, Petit C, et al., 2026,
Generalized Statistical Isotherm for Modeling Adsorption Equilibria in Stimuli-Responsive Framework Materials.
, LangmuirDesigning large-scale adsorption-based separation units requires a multiscale understanding of material behavior, from molecular interactions to process-level performance. An underpinning challenge is the development of predictive multicomponent adsorption equilibrium models for systems departing from the classic type I isotherm for microporous adsorbents. Adsorbents that undergo adsorption-induced transitions (flexible adsorbents) belong to this category and are a class of framework materials that exhibit unique features such as sigmoidal equilibrium isotherms and intrinsic thermal management capabilities. Despite their promise for practical applications, flexible adsorbents remain underexplored at the process scale due to the lack of a suitable equilibrium isotherm model that mechanistically captures their adsorption-induced structural transitions. Here, we present a simplified statistical isotherm model for transition materials (SSI-T) as a generalized approach to parametrize─using a combination of sorbate-dependent and -independent physical parameters─the adsorption equilibria in flexible adsorbents that exhibit a broad range of structural and configurational transitions upon adsorption. We have validated the model using unary and binary equilibrium data for gate-opening, breathing, and configurational transitions in multiple adsorbent-adsorbate systems. Our formulation represents the first continuous, differentiable, and explicit isotherm model in the literature capable of accurately describing unary adsorption and desorption isotherms in flexible adsorbents, and predicting binary equilibria for multiple types of adsorption-induced transitions without any additional parameters. Because SSI-T is an explicit function of state variables, it can be seamlessly integrated into process-scale simulators, enabling the design and optimization of adsorption-based technologies that use flexible adsorbents.
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Journal articleFerre A, Wedler C, Ward A, et al., 2026,
Co-production of high-purity carbon dioxide and methane via a single-bed pressure-vacuum swing adsorption process
, Separation and Purification Technology, ISSN: 1383-5866Pressure–vacuum swing adsorption is a promising technology to produce methane (CH4) and capture carbon dioxide (CO2) from biogas. Yet, processes for the simultaneous production of both heavy (CO2) and light product (CH4) at high-purity require several cycle steps (and, accordingly, columns) and/or multi-stage configurations. Here, we consider a simple 4-step cycle that can be implemented in a single bed and evaluate nine adsorption datasets, including zeolites, metal–organic frameworks, and activated carbon. Using a combination of equilibrium-based and detailed dynamic process models, we have carried out unconstrained purity/recovery optimizations as well as constrained optimizations considering both recovery–recovery and energy–productivity trade-offs. Zeolite NaY, zeolite 13X, and MIL-160(Al) are identified as top performers With zeolite NaY, CO2 purity >95%, CO2 recovery >86%, CH4 purity >97% and CH4 recovery >91% are achieved. Two independent NaY datasets led to notably different recoveries (up to 10%deviation), underscoring the sensitivity of process performance to the quality of adsorption isotherm data. The equilibrium-based model reproduces adsorbent rankings of the detailed dynamic model with moderate fidelity. As such, this study extends the application of this computationally efficient first-pass screening tool to biogas applications, while also emphasizing that reproducible and harmonized adsorption data are critical for robust materialscreening and process design.
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Journal articleBüchner D, Pini R, 2026,
Unary and binary dynamic column breakthrough experiments with carbon dioxide and nitrogen imaged by x-ray computed tomography
, Langmuir, Vol: 42, Pages: 14716-14732, ISSN: 0743-7463This study extends the digital adsorption (DA) method─i.e., adsorption experiments augmented with X-ray computed tomography (XCT)─from unary systems with strongly adsorbing CO2 to unary systems with weakly adsorbing N2 and to binary systems involving both species. Using this method, equilibrium adsorption isotherms on commercial activated carbon and zeolite 13X were measured for both gases at 294.15 K between 0.1 and 9 bar. Our analysis shows that X-ray attenuation by the bulk phase must be considered for weak adsorbates, while it is relevant only at elevated pressures for strong adsorbates. Unary dynamic column breakthrough (DCB) experiments with N2 showed that, with a correction factor, the DA method can describe the transient progression of the internal adsorbed phase under near-isothermal, equilibrium-controlled conditions quantitatively. In binary CO2–N2 DCB experiments, the direct determination of adsorbed amounts requires local composition data; however, when complemented by a one-dimensional DCB model, the experimental results are shown to capture dynamic adsorption behavior, including fast N2 and slower CO2 uptake, as well as a thermally enhanced roll-up. These results demonstrate that XCT provides valuable insight into dynamic adsorption processes and that, with care, the DA method can also be applied to weakly adsorbing systems.
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Journal articlePini R, Petit C, Danaci D, et al., 2026,
CO₂ capture by adsorption: research progress and technology demonstration
, International Journal of Greenhouse Gas Control, Vol: 153, ISSN: 1750-5836Adsorption is one of the main technologies proposed for CO₂ capture from industrial emitters. Although adsorption has been demonstrated at scale for other gas separations, its application to CO₂ capture remains an active area of research and field demonstration, owing to the complexity of feed streams (e.g., CO2 content, impurities) and the need to balance several process key performance indicators (e.g., purity and recovery of CO2 product). In this work, we take stock of the field’s progress, considering both research findings and demonstrations projects reported to date. We critically review the most relevant adsorption processes for different feed streams, depending on their composition, and highlight both established and emerging approaches for process modelling, design and optimisation. Importantly, we compile for the first time a traceable list of pilot- and full-scale CO₂ capture demonstration projects worldwide. We analyse the key technical challenges facing the field and identify priority areas for future research. Our report underscores the substantial body of knowledge accumulated on adsorption-based CO₂ capture processes over the years, their technical viability, and potential pathways toward commercial deployment.
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Journal articleTan J, He Y, Xiao N, et al., 2026,
A climate-driven generative scenario framework for optimizing integrated energy systems with hybrid storage solutions
, Progress in Energy, Vol: 8As renewable energy sources (RESs), particularly wind and solar, become increasingly integral to the urban energy mix, optimizing integrated energy systems (IES) is essential to ensuring sustainability and resilience. The inherent variability and intermittency of RES pose significant challenges for urban energy planning, demanding robust methods to simulate local climate patterns and support reliable energy storage strategies. This study presents a climate-responsive generative model Wasserstein generative adversarial network with gradient penalty-MD based on adversarial learning to produce high-fidelity wind and solar generation scenarios. Embedded within a Monte Carlo-based decomposition optimization framework, the model balances stochastic fidelity and computational tractability for large-scale IES planning. A case study conducted in a high-RES potential region demonstrates the model’s effectiveness in supporting informed system design and operational strategies. By introducing a novel quantitative metric, results reveal the complementary roles of battery energy storage systems and hydrogen storage in addressing short-term variability and long-term balancing needs. Notably, annual renewable generation can deviate by over 40.5% under extreme climate conditions, highlighting the necessity of hybrid storage strategies. The proposed approach enhances system reliability and economic viability under diverse climate scenarios. Key contributions include: (1) the development of a climate-informed generative model for RES scenarios, (2) its integration into an computationally efficient Monte Carlo-based optimization framework for IES, and (3) a hybrid storage strategy that reinforces the resilience and sustainability of urban energy systems. These findings offer practical insights for advancing low-carbon, climate-adaptive urban infrastructure in the transition toward sustainable cities.
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Journal articleJoewondo N, Garbin V, Pini R, 2026,
Coupled dissolution and diffusive interactions of microbubbles in irregular pore networks
, Transport in Porous Media, Vol: 153, ISSN: 0169-3913The dissolution of a dispersed gas phase in a porous medium partially saturated with liquid is a problem of broad practical interest. While capillary equilibration has been shown to affect the evolution of the dispersed phase, its coupling with the underlying diffusive process in the liquid phase remains largely unexplored. Here, we deploy a pore-network model to describe coupled dissolution and diffusive interactions of a lattice of microbubbles in irregular pore networks. We demonstrate that the dissolution process becomes more erratic than in regular networks, because of the complex interplay between local connectivity effects and diffusive shielding between neighboring bubbles. By applying the method of moments, we quantify the evolution of solute mass in the system and compute continuum-scale properties, such as the effective diffusion coefficient of the network and the dissolution rate of the bubble lattice. We observe that the presence of bubbles delays the attainment of an asymptotic diffusive behavior and reduces the spatial extent of the solute plume relative to the same liquid-saturated network. Importantly, collective effects appear to be stronger than effects associated with the local pore connectivity distribution in the network in reducing the rate of dissolution of bubbles. Article Highlights Local connectivity and collective effects control the dissolution of microbubbles in irregular pore networks Bubbles can grow significantly before undergoing complete dissolution The presence of bubbles delays the dissolution process and reduces the spatial extent of the solute plume relative to a bubble-free network The complex topology of practical porous media may strengthen collective effects even further
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Journal articleFeng Z, Stanwix PL, Trusler JPM, 2026,
Ammonium salts formation in impure CO2 transport streams
, International Journal of Greenhouse Gas Control, Vol: 153, ISSN: 1750-5836An experimental and modelling study is presented concerning the thermodynamics and kinetics of ammonium salts formation in an impure carbon dioxide stream. Thermodynamic modelling is used to determine the conditions at which ammonium carbamate and ammonium bicarbonate are stable in terms of temperature, pressure and the mole fractions of both ammonia and water in the CO<inf>2</inf> stream. The conditions investigated are gas, liquid and supercritical states at temperatures between (273 and 313) K with pressures up to 10 MPa. The calculations show that ammonium carbamate may form in dry gaseous CO<inf>2</inf> when the ammonia mole fraction exceeds 10 ppm. If water is also present at 50 ppm, then ammonium bicarbonate is more stable in a wide range of conditions and may form at the lowest temperature even with 1 ppm of ammonia present. These salts ate predicted to exhibit even greater stability in cryogenic liquid CO<inf>2</inf>. Batch reactor experiments show that ammonium carbamate forms very rapidly and, in our study, both ex situ FTIR and in situ Raman spectroscopy were used to identify the salts formed. In the presence of water impurity, ammonium bicarbonate was found to form either directly from the gas phase or via hydrolysis of ammonium carbamate.
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Journal articleChakraborty S, Fennell P, 2026,
Investigation on the cyclic CO₂ capture behaviour and degradation mechanism of molten salt promoted MgO derived from commercial hydromagnesite
, Carbon Capture Science & Technology, ISSN: 2772-6568This study examines the cyclic CO2 capture performance and degradation mechanism of molten salt-promoted MgO, a low-cost and scalable precursor, derived from commercially available hydromagnesite. The material was modified using different nitrate-based molten salt compositions to enhance CO2 uptake. Among the formulations, single- and double-salt-promoted MgO exhibited the highest initial capture capacities; however, performance declined with repeated cycling. Notably, the single-salt system demonstrated comparatively better stability over 10–22 cycles than others. The observed reduction in CO2 capture capacity is attributed to the gradual loss and transformation of nitrate species, which reduces the effective molten phase and pore blockage. Thermodynamic analysis supports the conversion of active nitrate phases into less effective forms during cycling, while X-ray diffraction and ICP-MS confirm a decrease in nitrate content despite minimal change in overall sodium levels. These findings highlight the critical role of molten salt stability in sustaining CO2 capture performance and provide insight into the design of more durable MgO-based sorbents.
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Journal articleHarris C, Krevor S, Muggeridge AH, et al., 2026,
Rate Dependency of Capillary Heterogeneity Trapping for CO2 Storage
, Water Resources Research, Vol: 62, ISSN: 0043-1397In this paper, we experimentally quantify and analytically model rate dependent capillary heterogeneity trapping. Capillary heterogeneity trapping enhances non-wetting fluid trapping beyond pore-scale residual trapping through the isolation of non-wetting phase upstream of heterogeneities in the continuum capillary pressure characteristics. Whilst residual trapping is largely insensitive to the range of flow regimes prevalent in engineered reservoir settings, continuum theory anticipates that capillary heterogeneity trapping will be more sensitive to the balance of viscous and capillary forces that occur. We perform steady-state drainage and imbibition multiphase flow experiments at varying flow rate on a layered Bentheimer sample with in situ medical X-ray CT scanning to quantify saturation. Saturation discontinuities are observed upstream of capillary pressure barriers as a result of capillary pressure discontinuities, trapping the non-wetting phase at a saturation greater than pore-scale residual trapping alone. We confirm the flow rate dependence predicted by theory whereby the relationship between the initial and residual saturations approach a 1:1 dependence as flow rate is decreased. We develop a one-dimensional analytical model to quantify the proportion of capillary heterogeneity trapping in the system and the dimensionless trapping length scale, which agrees with the experimental data and allows for rapid estimates of trapping.
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Journal articleHarris C, Krevor S, Muggeridge AH, et al., 2026,
Unstable Drainage Dynamics During Multiphase Flow Across Capillary Heterogeneities
, Geophysical Research Letters, Vol: 53, ISSN: 0094-8276We use novel, fast 4D Synchrotron X-ray imaging with large field-of-view to reveal pore- and macro-scale drainage dynamics during gas–brine flow through a layered sandstone rock sample. We show that a single centimeter-scale layer, similar in pore size distribution to the surrounding rock but with reduced connectivity, temporarily inhibits, and redirects gas flow, acting as a capillary barrier. Subtle variations in gas invasion upstream of the barrier lead to different downstream migration pathways over repeated experiments, resulting in unstable and unpredictable drainage behavior, with breakthrough times varying by up to a factor of four. The results show that heterogeneity in pore-scale connectivity can amplify variability in macroscopic flow, challenging deterministic assumptions in existing continuum models. By linking structural heterogeneity to flow instability, this work underscores the need for probabilistic modeling approaches in multiphase flow and highlights broader implications for managing fluid transport in natural and engineered porous systems.
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Journal articleAi L, Trusler JPM, 2026,
Experimental study of hydrogen-brine interfacial tension: Implications for natural hydrogen production
, International Journal of Hydrogen Energy, Vol: 224, ISSN: 0360-3199Experimentally determined interfacial tensions (IFT) of the H<inf>2</inf>–NaCl (aq) system are reported, with NaCl molalities of (0, 1, 3 and 5) mol·kg−1 at temperatures from (298.15 to 423.15) K and pressures from (0.5 to 30) MPa. Measurements were conducted using the pendant drop method. The IFT was found to decrease with increasing temperature and pressure, while increasing NaCl concentration led to higher IFT. Surface tension values extrapolated from the IFT data showed good agreement with literature values, validating the reliability of the measurements. A linear dependence of IFT on NaCl molality was identified, enabling development of an empirical correlation incorporating temperature, pressure, and NaCl molality that fits the experimental data well, with an average absolute deviation of 0.24 mN⋅m−1. These results provide a validated dataset for modelling interfacial phenomena in hydrogen-water/brine systems relevant to geological hydrogen production and storage.
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Journal articleDarraj N, Manoorkar S, Spurin C, et al., 2026,
Impact of pore-scale heterogeneity on continuum-scale multiphase flow properties: Insights from Indiana limestone
, International Journal of Greenhouse Gas Control, Vol: 151, ISSN: 1750-5836Microscale heterogeneity in porous media can influence larger-scale multiphase flow behaviour, particularly in the context of CO<inf>2</inf> storage. We conducted a multiphase steady-state flooding experiments on Indiana limestone, a carbonate with millimetre-scale heterogeneity, at two flow rates with capillary numbers of N<inf>c</inf> = 5 × 10<sup>−8</sup>and 1 × 10<sup>−7</sup>. Micro-CT at a 4.9 µm resolution was used to image nitrogen–brine displacement: the analysis included the whole sample and six representative sub-volumes from distinct regions.The analysis shows that doubling the capillary number produced a more homogeneous saturation profile, reflecting the greater influence of viscous forces even within a predominantly capillary-controlled regime. Moreover, the relative permeabilities shifted upward and to higher brine saturation with decreasing flow rate; this indicated that the non-wetting phase benefits from enhanced connectivity through preferential pathways. As the flow rate increases, however, viscous forces begin to override local capillary entry barriers, enabling the non-wetting phase to invade smaller and previously uninvaded pores. The sub-volume analysis showed two distinct regions with different entry pressures: the regions with higher entry pressure exhibit a higher gas invasion at the higher flow rate, whereas low capillary entry pressure regions showed minimal change.These observations show that modest increases in capillary number can change relative permeability, saturation, and trapping. This underlines the need to represent capillary heterogeneity when upscaling flow properties for reservoir-scale simulation of subsurface CO₂ storage. Relative permeability models that neglect sub-grid variability may bias simulated plume migration and trapping efficiency, and therefore the inferred storage performance.
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Journal articleBecattini V, Gazzani M, Pini R, et al., 2026,
Marco Mazzotti─Advancing Separation Science through Education, Innovation, and Real-World Impact
, Industrial and Engineering Chemistry Research, Vol: 65, Pages: 2979-2983, ISSN: 0888-5885 -
Journal articleLeonzio G, Shah N, 2026,
C2 and C+ compound production from carbon dioxide: supply chain design and optimization
, Computers and Chemical Engineering, Vol: 205, ISSN: 0098-1354The use of carbon dioxide to produce chemical products can in principle decrease both fossil resource exploitation and greenhouse gas emissions. Potential compounds that can be obtained are ethylene and polyurethane, characterized by large markets underpinning many industries. The importance of such platform chemicals means that different routes have been investigated in the literature for their alternative synthesis. However, there is lack of a direct comparison of these products and processes in a carbon capture utilization and storage supply chain in the existing literature: a gap which we wish to address here.A mixed integer linear optimization model for a carbon capture utilization and storage supply chain is developed here: carbon dioxide can be extracted from flue gas to be stored and/or utilized for ethylene (via the tandem or methanol to olefin processes), polyethylene or polyurethane production and these can be either sold immediately or stored. The framework is exemplified by a case study localised within the UK Teesside petrolchemical cluster and the best topology is suggested to minimize total costs. Moreover, a dynamic analysis of the system over the years is considered here to suggest the best way to implement carbon dioxide capture and utilisation through to 2050. Results show that the optimal cost is achieved by capturing carbon dioxide and converting it into ethylene via the methanol-to-olefin process; the whole system levelized cost is 7.3 $/kgEthylene. Moreover, ensuring an homogeneous way of capturing carbon dioxide over time maximises the profitability of the overall system.
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Journal articleSpreng TL, Danaci D, Ram PD, et al., 2026,
Amine-Appended Hyper-Crosslinked Polymers for Direct Air Capture of CO2.
, ACS Sustain Chem Eng, Vol: 14, Pages: 1834-1846, ISSN: 2168-0485Capturing CO2 from the ambient atmosphere is a promising method to reduce the impact of climate change. Fast deployment and scale-up of adsorption-based direct air capture (DAC) technologies are needed to meet the IPCC target and rely, in part, on the development of efficient and scalable low-cost adsorbents. While a benchmark DAC adsorbent, the polymeric resin Lewatit VP OC 1065, has been established, the reasons behind its performance and the potential for further optimization remain largely unknown. Indeed, a fundamental understanding of the relationship between adsorbent pore structure, chemistry, and DAC performance, both equilibrium and kinetics, has yet to be formulated. Here, we have built on the chemistry of Lewatit and synthesized a hyper-crosslinked polymer (HCP) by grafting a microporous chlorine-functionalized support with diethylenetriamine. We produced four different adsorbents by varying the polymerization duration between 10 min and 19 h to assess the impact of pore structure on CO2 uptake at 400 ppm. Reduced degrees of polymerization (i.e., shorter polymerization durations) resulted in higher accessible micropore volume and consequentially increased CO2 uptake and amine efficiency. The best sample achieved an equilibrium uptake of 0.43 mmol/g (400 ppm of CO2, 298 K), which is about half that of the benchmark adsorbent Lewatit VP OC 1065. We have then assessed the CO2 sorption kinetics of this sample (grain size of 24-74 μm) at 400 ppm and 303 K using a gravimetric technique and have compared the results to those of other amine-grafted polymeric adsorbents. We measured a lower bound linear driving force constant (k LDF) of 0.0120 ± 0.0004 s-1. This value is 5.5 times faster than that of the benchmark adsorbent Lewatit VP OC 1065 with the same grain size of 24-74 μm, highlighting the importance of macropore diffusion in addition to the CO2 reaction kinetics. This study shows how synthesis operating conditions alter the pore structures an
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Journal articleGhaedi H, Fu J, Meng X, et al., 2026,
Iono non-hydrothermal (INH) method for synthesis of highly ordered mesoporous silica materials
, Chemical Engineering Journal, Vol: 528, ISSN: 1385-8947Highly ordered mesoporous silica materials (HOMMs) are widely valued for applications in catalysis, adsorption, and energy storage, but their traditional synthesis suffers from lengthy hydrothermal aging, high-temperature calcination, toxic swelling agents, and irreversible loss of the expensive Pluronic P123 template. Herein, we introduce a novel Iono Non-Hydrothermal (INH) method that completely eliminates both hydrothermal treatment and calcination. Green deep eutectic solvents (DESs) are employed in a multifunctional role as reaction medium, swelling agent, and low-temperature (120 °C) de-templating agent. The optimized ternary DES enables efficient template removal while preserving abundant surface silanol groups. The resulting HOMMs exhibit high surface area (up to 777 m<sup>2</sup>/g), uniform pore size (∼7.8 nm), and excellent structural order comparable to conventionally synthesized SBA-15. The influence of synthesis pH (adjusted by NH₄OH) and DES composition on pore structure and hydrothermal stability is systematically investigated, revealing that higher condensation pH significantly enhances resistance to boiling-water degradation. Importantly, simple ethyl acetate extraction of the post-synthesis filtrate allows recovery of P123 together with the DESs, establishing a near-closed material loop. A preliminary techno-economic analysis demonstrates 81–87 % material cost reduction, 50–67 % lower energy consumption, and > 32 % higher throughput compared to the conventional hydrothermal-calcination route. The INH strategy thus offers a sustainable, scalable pathway for producing high-performance mesoporous silica materials with substantially reduced environmental impact and production cost.
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Journal articleWang K, Zhao P, Zhou T, et al., 2026,
High-temperature CO2 capture and in-situ conversion over bifunctional Na2ZrO3 self-catalyst/sorbent for circular CO production
, Chemical Engineering Journal, Vol: 528, ISSN: 1385-8947CO<inf>2</inf> capture and utilization to produce value-added fuels and chemicals offers a promising avenue to assist in the mitigation of the global warming crisis. However, there are economic challenges for the regeneration of some sorbents used in CO<inf>2</inf> capture, owing to sorbent sintering and high energy requirements, while direct conversion processes are hindered by the lack of cost-effective, efficient, selective, and stable catalysts. We demonstrate the use of sodium zirconate-looping (NaL) with the reverse-Boudouard (RB) reaction enabling high-temperature CO<inf>2</inf> capture and in-situ CO<inf>2</inf> conversion operating in a single isothermal reactor operating at 800 °C. While employing a mild combustion synthesis method, the dual-function material Na<inf>2</inf>ZrO<inf>3</inf> exhibited a high and stable CO<inf>2</inf> uptake capacity of 4.9 mmol CO<inf>2</inf>/g without the use of Ni catalysts. This is due to its fine particle size, macroporous structure, and well-dispersed ZrO<inf>2</inf> stabilizer within the Na<inf>2</inf>O matrix. The resulting Na<inf>2</inf>CO<inf>3</inf>-ZrO<inf>2</inf> and regenerated Na<inf>2</inf>ZrO<inf>3</inf> phases (as synergistic self-catalysts) mixed with renewable and cost-effective biochar (as a reductant) facilitated exceptional in-situ CO<inf>2</inf> conversion efficiency (∼90 %), as well as high CO selectivity (approaching 100 %), and relative stability (∼80 %) even after multiple cycles. Importantly, theoretical calculations aligned with mechanistic studies revealed that the activation energy barriers at two specific oxygen sites for the monatomic C-assisted CO<inf>2</inf> dissociation/gasification were lower than the desorption energy of CO<inf>2</inf> on the Na<inf>2</inf
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Journal articleAlanazi K, Shah N, Mittal S, et al., 2026,
Competition and equilibrium in future global renewable hydrogen trade: a game-theoretic analysis
, Applied Energy, Vol: 402, ISSN: 0306-2619Global renewable hydrogen trade is expected to play a key role in decarbonizing future energy systems. Yet hydrogen exporters may deviate from perfectly competitive behaviour to influence prices, similarly to the existing fossil fuel market, with important implications for consumer welfare and the pace of the energy transition. This study develops a global renewable hydrogen trade model that captures potential strategic interactions among exporters using a Stackelberg game-theoretic framework. The model is formulated as an Equilibrium Problem with Equilibrium Constraints (EPEC) and solved under three alternative equilibria: a profit-maximizing Nash equilibrium, a cost-minimizing Nash equilibrium, and a welfare-maximizing benchmark representing perfect competition. Results indicate that producers may strategically reduce their export quantities by up to 40 % relative to perfect competition to maximize profits. Such behaviour raises prices to a minimum of 4.5 USD/kg in 2050 across major import markets, thereby significantly eroding consumer surplus. Strategic behaviour of dominant exporters also shifts trade flows, reshaping the global allocation of hydrogen supply. Sensitivity analysis further reveals that financing costs play a key role in shaping strategic producers' behaviour, with lower financing costs helping to reduce prices and stimulate demand. These findings highlight the implications of imperfect competition in global hydrogen trade and suggest that policy measures may be needed to mitigate potential negative consequences.
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Journal articleRestelli F, Jiao F, Norris B, et al., 2026,
Dynamic simulation of a liquefied hydrogen export terminal
, Energy, Vol: 342, ISSN: 0360-5442At prospective liquid hydrogen (LH<inf>2</inf>) export terminals, managing boil-off gas (BOG) presents a significant challenge that has not been adequately explored in the literature. This work is a case study examining the management of BOG evolved during storage and carrier loading at an export terminal, carried out using detailed dynamic simulations. The considered terminal operates with a LH<inf>2</inf> production rate of 450 t/d, and a carrier capacity of 160000 m<sup>3</sup>. The normal operation cycle spans a period of 28 days, during which all the generated BOG is recovered. The estimated levelized cost for terminal storage and shipment is 2.77 USD/kg, underlining the need for further research to reduce costs and enhance the economic viability of LH<inf>2</inf> export. A sensitivity analysis indicates that the production rate primarily affects the duration of the normal operation cycle and, consequently, shipping frequency, while feed pressure and ortho-para hydrogen composition significantly influence total BOG generation.
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Journal articleDelpisheh M, Moradpoor I, Souhankar A, et al., 2026,
Advancing the hydrogen economy: Economic, technological, and policy perspectives for a sustainable energy transition
, RENEWABLE & SUSTAINABLE ENERGY REVIEWS, Vol: 226, ISSN: 1364-0321 -
Journal articleZanobetti F, Bernardi A, Pio G, et al., 2025,
Quantitative sustainability assessment of e-fuels for maritime transport
, Sustainable Energy and Fuels, Vol: 9, Pages: 6506-6521, ISSN: 2398-4902Reducing the carbon intensity of maritime transport is essential to achieve global emission reduction targets. Electro-fuels (e-fuels) represent a promising cleaner alternative to conventional marine fossil fuels, offering potential lifecycle greenhouse gas reductions when synthesised from renewable electricity and low-carbon feedstocks. While techno-economic and environmental assessments of e-fuels exist, their broader sustainability implications, spanning technological, economic, environmental and safety factors together, remain largely unexplored. This study introduces a quantitative framework to assess the sustainability of ship fuel systems that integrates key performance indicators (KPIs) across these four areas. A case study is conducted to compare the sustainability of carbon-based e-fuels (e-methanol and e-diesel) and carbon-free e-fuels (hydrogen and ammonia) against marine diesel oil (MDO) under multiple decision-making perspectives. The robustness of the overall sustainability-based ranking of fuel alternatives, as derived under each perspective, against uncertainties in the individual KPIs is confirmed via sensitivity analysis. Environmental and safety aspects are found to be critical in comparing the sustainability of alternative fuels. Both e-methanol and e-diesel achieve higher overall sustainability than MDO, irrespective of the decision-making perspective. Ammonia and hydrogen are hindered by safety concerns in the short term, although ammonia also shows long-term potential for sustainable shipping subject to appropriate risk management and the implementation of inherently safer design measures. Overall, the proposed framework enables a comprehensive assessment of alternative fuel systems for cleaner shipping, guiding future sustainability-driven policy and technology development.
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Journal articleChen Q, Trusler JPM, 2025,
Olivine dissolution kinetics at elevated temperatures and pressures
, Chemical Engineering Journal, Vol: 525, ISSN: 1385-8947Experimental and modelling studies of the dissolution kinetics and surface chemistry of olivine in CO2-saturated water at elevated temperatures and CO2 pressures are reported. The apparent initial dissolution rates of olivine are reported at temperatures between 373 and 473 K and at pressures between 7.7 and 15.6 MPa. The influence of mass transfer effects on olivine dissolution and the formation of passivation layers were studied, and the minimum stirring speed at which mass transfer resistance was effectively eliminated was determined. The optimum temperature for olivine dissolution in the long term was determined to be approximately 423 K. This study provides the first data for olivine dissolution rates at temperatures above 423 K. The initial olivine dissolution rates did not show a monotonic increasing trend with the increase of temperature due to the formation of various passivation layers on the olivine particle surfaces at different temperatures. A simple model, dependent upon temperature and the activity of H+, was developed to represent the experimental data. This model is generally applicable under similar temperature and pressure conditions, and when the same type of passivation layer is present. Based on the proposed model, the PHREEQC geochemical simulator was used to predict the saturation indices of Fe2O3 (hematite), FeO(OH) (goethite), Fe(OH)3 (ferric hydroxide) and SiO2 (both quartz and amorphous silica). The pH and elemental concentrations were also predicted and these calculations served to partially rationalize the experimental results.
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