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• Mechanisms of the effect of Na on coal-based soot formation in pyrolytic atmospheres with different concentrations of CO 2. • CO 2 promotes both oxidation and addition processes of soot. • The structure of Na-π electron complexes, which changes the charge distribution of PAHs, reduces the reaction energy barrier for CO 2 oxidation of benzene rings. Fossil fuels are wasteful, and they pollute the environment when utilized as energy sources. Soot from the incomplete combustion of fossil fuels has received considerable attention due to its harmful effects on the environment and the human body, and its utilization value in terms of materials. In this study, experiments on the pyrolysis of coal mixed with sodium carbonate (NaNO 3) at different carbon dioxide (CO 2) concentrations were conducted on a drop tube furnace. Experimental results were explained using density functional theory (DFT) calculation by constructing structural models of the oxidation of naphthalene with and without sodium (Na) involvement. The results showed that the average particle size of soot decreased from 29.7 nm to 21.44 nm with an increase in CO 2 concentration before the addition of Na. After the addition of Na, particle size exhibited a tendency of decreasing and then increasing, indicating that CO 2 exerted oxidizing and adducting effects on soot. In an atmosphere with a high concentration of CO 2 , Na promoted the adducting effect, and particle size increased to 34.86 nm. Moreover, the addition of Na significantly increased oxygen content on the surface of soot, indicating that the participation of Na enhanced the oxidation reaction of soot. The results of the DFT calculations also proved that Na facilitated the occurrence of oxidation reaction by decreasing the energy barrier required for oxidation reaction from 9.28 kcal/mol to −64.62 kcal/mol through the transfer of electrons and the formation of active centers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A theoretical investigation presents pristine triphenylene-graphdiyne (tpGDY), BN-modified and nitrogen-doped derivatives as electrocatalysts for CO 2 reduction to valuable products. • TpGDY, tpGDY-BN, and tpGDY-N08 show strong catalytic activity with U L =0 V for CO 2 reduction to CO and HCOOH. • With low U L of −0.18 V and −0.27 V, N-doped tpGDYs, specifically tpGDY-N01 and tpGDY-BN-N01, demonstrate electrocatalytic selectivity to CO 2 conversion to CH 3 OH. • Overpotentials of 0.84 V for tpGDY-N01 and 0.71 V for tpGDY-BN-N01 facilitated C 2 H 5 OH, C 2 H 4 and C 2 H 6 products through *CHO+*CO intermediates. The potential of carbon-based triphenylene-graphdiyne (tpGDY) and its derivatives for the electrochemical CO 2 reduction reaction (eCO 2 R) was comprehensively explored using density functional theory (DFT) calculations. Six variants were studied: pristine tpGDY, tpGDY-BN, tpGDY-N01, tpGDY-N02, tpGDY-N08, and tpGDY-BN-B01. Pristine tpGDY, tpGDY-BN, and tpGDY-N08 exhibited exceptional catalytic activity, efficiently converting CO 2 into CO and HCOOH without external energy input. Significantly, N-doped tpGDY catalysts incorporating sp2-hybridized nitrogen atoms at the acetylenic sites (tpGDY-N01 and tpGDY-BN-N01) demonstrated remarkable electrocatalytic activity for the targeted conversion of CO 2 to CH 3 OH. This outstanding performance is further corroborated by the low limiting potentials of −0.18 V and −0.27 V for tpGDY-N01 and tpGDY-BN-N01, respectively, highlighting their economic viability. Furthermore, the feasibility of C2 production (e.g., C 2 H 5 OH, C 2 H 4 and C 2 H 6) through C–C coupling of *CHO+*CO intermediate was investigated for tpGDY-N01 and tpGDY-BN-N01. DFT calculations suggest these pathways are achievable but require potentials of 0.84 V and 0.71 V for tpGDY-N01 and tpGDY-BN-N01, respectively. This study demonstrates the efficacy of N-doped tpGDY as a metal-free electrocatalyst for CO 2 reduction, enabling the generation of both C1 and C2 products. This discovery holds significant promise for the advancement of sustainable CO 2 conversion technologies. [ABSTRACT FROM AUTHOR]

• A generalized adsorption model of CO 2 -CH 4 in shale is built. • The Langmuir model is improved by building relations of Q 0 and P L with T , TOC and x CO 2 . • This model can accurately predict adsorption properties of CO 2 , CH 4 and their mixture. • This work provides some theoretical basis for adsorption evaluation in CO 2 -ESGR. CO 2 enhanced shale gas recovery (CO 2 -ESGR), as one of the most promising carbon capture, utilization and storage (CCUS) technologies, can both improve the shale gas production for clean energy supply and mitigate greenhouse gas emissions for the goal of carbon neutrality. The adsorption characteristics of CO 2 and CH 4 in shale play a key role in the reserve assessment of shale gas and the implementation of CO 2 -ESGR. The problem of accurate prediction of the adsorption and competitive adsorption characteristics of CO 2 and CH 4 in shale is still one of the main challenges for CO 2 -ESGR. To bridge the gap, this work developed a generalized prediction model for the adsorption properties of CH 4 , CO 2 , and their mixed gas in shale by improving the Langmuir model, covering a large range of temperature, pressure, and total organic carbon content (TOC). The mathematical models for the key parameters of the Langmuir model, the saturated adsorption capacity Q 0 and Langmuir pressure P L , were built for the single-component gas based on their functional relationship with temperature and TOC, and for the mixed gas based on their relationship with Q 0 and P L of the single-component gas and CO 2 content. Then an improved Langmuir model for the adsorption properties of CO 2 -CH 4 in shale was established. The accuracy of the improved model was verified with a relative deviation below 5 % in a large range of temperature (303–363 K), pressure (0–15 MPa) and TOC (1.06 %-3.83 %) by comparing the calculated adsorption with the experimental data. This generalized adsorption model not only ensures the prediction accuracy of CO 2 -CH 4 adsorption characteristics in shale but also expands its application convenience in a large range of temperatures, pressures and TOC, providing a certain theoretical basis for CO 2 -ESGR technology. [ABSTRACT FROM AUTHOR]

• The phase behavior of CO 2 -oil mixtures in porous media is visualized using MRI. • CO 2 -oil MMPs in porous media are firstly estimated by MRI multiparameter method. • CO 2 solubility and saturated liquid density are estimated by MR relaxation rates. Accurate characterization of the CO 2 -oil mixtures phase behavior will be advantageous for CO 2 enhanced oil recovery (EOR) and reservoir production design for CO 2 geologic storage projects. Relevant properties which include density, oil swelling factor, solubility and minimum miscibility pressure (MMP) of CO 2 -oil are typically measured in the laboratory using the conventional time-consuming pressure–volume-temperature (PVT) method. In this study, the phase behavior of CO 2 -oil mixtures was characterized inside a porous medium at reservoir temperature and pressure using nuclear magnetic resonance imaging (MRI). This research method realizes direct observation and in situ measurement compared with PVT method, effectively reducing the experimental operating pressure and the pressure-loading limit of the measurement equipment. The CO 2 -oil mixture equilibrium pressures correlated exponentially with the corresponding proton density (M 0) and relaxation rates (1/ T 1 , 1/ T 2); thus, the MRI multiparameter method was first applied to estimate MMP by only measuring several equilibrium pressure points and extrapolating to zero. The CO 2 solubility and saturated liquid density linearly decreased as 1/ T 1 increased but linearly increased as 1/ T 2 increased, which indicates that these parameters can be estimated based on the magnetic resonance (MR) relaxation rates. The results demonstrate the remarkable advantage and feasibility of applying MRI techniques for in situ measuring of the physical properties of fluids in porous media within the laboratory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface Cr6+ and oxygen species were enriched to form Cr 2 O 7 2−. • Niδ+ species catalyzed the reaction between CO 2 and carbon deposit. • Carbon cycle-assisted oxygen cycle improved stability of Cr-based catalysts. • The 1Ni1CrO x /ZrO 2 produced ethylene steadily over a prolonged period of 38 h. The CO 2 -assisted oxidative dehydrogenation of ethane (CO 2 -ODHE) is known as an ecologically beneficial process for ethylene generation and CO 2 utilization. However, the quick deactivation of traditional Cr-based catalysts remains a considerable challenge. Herein, we report that a 1Ni1CrO x /ZrO 2 catalyst could be high active and stable for the CO 2 -ODHE reaction; it showed CO 2 conversion of 15.4 % and kept stable for 38 h at 600 °C, while the productivity of ethylene approached 325 μmol·min−1·g cat −1. Kinetic evaluations found a low apparent activation energy of 87.2 kJ/mol on the 1Ni1CrO x /ZrO 2 catalyst. Surface Cr6+ and oxygen species were enriched to form Cr 2 O 7 2− with the introduction of NiO. In addition, NiO improved the surface alkalinity and the affinity for oxygen, promoting the strong adsorption and easy activation of CO 2. Importantly, Niδ+ species catalyzed the reaction between CO 2 and surface-deposited carbon by redox cycling (carbon cycle), promoting Mars-van Krevelen-type carbon elimination and Cr6+ regeneration. The carbon cycle-assisted oxygen cycle on the Ni-Cr oxide catalysts could obviously enhance the carbon resistance and stable ethylene production, demonstrating potential application of Cr-based catalysts for CO 2 -ODHE reaction. [ABSTRACT FROM AUTHOR]

• A review from the thermodynamic and kinetic aspects for CH 4 -H 2 S reforming and CO 2 -H 2 S reaction. • Current technological methods used in CO 2 -H 2 S reaction to H 2 are reviewed. • Advancements in catalyst research for CH 4 -H 2 S reforming are summarized. • A summary of dry reforming of CH 4 reaction from a thermodynamic viewpoint. • Research progress on catalysts for dry reforming of CH 4 reaction is reviewed. H 2 is widely acknowledged as an essential renewable energy source. Approximately 96 % of the global H 2 is derived from fossil resources namely petroleum, natural gas, and coal, with natural gas producing H 2 at a significantly lower cost. When natural gas is processed and used, it often produces acid gases like H 2 S and CO 2. Current acid gases treatment technologies predominantly recover sulfur from H 2 S using the Claus process without treating CO 2 , leading to wastage of H 2 resources and substantial carbon emissions. In light of this, there is an attractive prospect in directly utilizing acid gases (H 2 S, CO 2 , CH 4 , etc.) for multi-component synergistic conversion. The approach not only facilitates the harmless treatment of H 2 S and CO 2 but also sustainably generates H 2. There are now a number of potential techniques for directly converting acid gases into H 2 , such as dry reforming of methane (DRM), reforming CH 4 with H 2 S, H 2 S pyrolysis, and CO 2 -H 2 S reaction. However, comprehensive reviews on these topics are still lacking. This paper provides a comprehensive review of the research progress in the synergistic conversion of CO 2 -H 2 S, reforming CH 4 with H 2 S, H 2 S pyrolysis, and DRM. It discusses in detail the thermodynamics, kinetics, and catalyst design of these reactions. Finally, the prospects and challenges for the application of the technical methods and catalysts for these three reactions are outlined. [ABSTRACT FROM AUTHOR]

• The LBV of CH 4 /H 2 /O 2 /CO 2 was measured using an improved heat flux burner. • The LBV of CH 4 /H 2 was by the first time studied under high H 2 and O 2 content. • Five popular detailed mechanisms were evaluated using the measured LBVs. • The thermal and chemical effects of H 2 and CO 2 on the LBV were analyzed. The oxy-fuel combustion of coke oven gas generates CH 4 /H 2 /O 2 /CO 2 mixtures, and this study focuses on measuring the laminar burning velocities of these mixtures which are rarely studied previously. The investigation encompasses a range of equivalence ratios from 0.6 to 1.5, O 2 /(O 2 + CO 2) ratios varying between 0.25 and 0.38, and H 2 /(H 2 + CH 4) ratios ranging from 0.25 to 0.6, under normal temperature and pressure conditions. Employing the experimental data, five established detailed kinetic mechanisms (Konnov 2023, AramcoMech 3.0, GRI 3.0, USC II, and San Diego) are evaluated, revealing that the Konnov 2023 mechanism exhibits the best performance in predicting the laminar burning velocities. Notably, the thermal effect of H 2 demonstrates a small impact on laminar burning velocity, with the chemical effect being considerably more significant, since the addition of H 2 directly increases concentrations of H, O, and OH, thereby accelerating the global reaction rates of both H 2 and CH 4 oxidation. Conversely, the thermal effect of CO 2 , attributable to its high specific heat, results in a reduction of the laminar burning velocity. Furthermore, the chemical effect of CO 2 is found to be comparable to the thermal effect, primarily arising from the elementary reaction CO + OH <=> CO 2 + H. It is noteworthy that the third-body reactions involving CO 2 exhibits relatively small effects. [ABSTRACT FROM AUTHOR]

[Display omitted] • Al replaces Zn in the ZnO lattice, favoring the formation of oxygen vacancies (V o); • The maximum methanol formation rate occurs when the number of Vo is at its maximum; • Beyond Al solubility limit in ZnO, other phases are formed, hindering catalysis; • CO 2 adsorption occurs on the Cu and the mixed oxide interface; • One of the O atoms of CO 2 replenishes the Vo and the other interacts with Cu. Cu, Zn, and Al-based catalysts were prepared, characterized, and tested in order to describe the role of Al in the CO 2 hydrogenation to methanol. This work shows that Al3+ replaces Zn2+ in the ZnO lattice, promoting the generation of oxygen vacancies (V o) on the oxide surface. When the Al and V o concentration increases, the rate of methanol formation also increases. Once Al3+ solubility in ZnO is reached this rate decreases. An Al-based compound is formed which occludes a portion of the catalyst's surface, changing the behavior of the catalyst. DFT calculations highlight the role of Al in methanol formation by lowering the energy required for the formation of V o. This species promotes the adsorption of CO 2 on the interface between ZnO and Cu0. Thus, both Al and V o show a pivotal role in the catalytic behavior of Cu/ZnO/Al. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimized parameters for stepwise pyrolysis are systematically investigated. • Low-temperature pyrolysis section is beneficial to biomass decomposition. • High-temperature pyrolysis section realizes the deoxygenation of intermediates. • Stepwise pyrolysis improves both the bio-oil yield and hydrocarbons selectivity. Stepwise pyrolysis is recognized as a promising method in converting biomass into sustainable bio-oils. However, a systematic study on the stepwise parameters (e.g. , low- and high-pyrolysis temperatures, duration, atmosphere) is still lacking. Herein, the stepwise catalytic fast pyrolysis (CFP) of cotton stove over ZSM-5 was conducted, aiming to reveal the impact of aforementioned parameters on bio-oils production. Results showed that the low-temperature pyrolysis benefitted the decomposition of biomass, while the high-temperature counterpart favored the upgrading of bio-oil. The combination of a low-temperature pyrolysis (400 ℃ for 2 min) and high-temperature pyrolysis (600 ℃ for 3 min) led to a satisfied hydrocarbons selectivity (35.8 area%) and bio-oil yield (11.4 wt%). This was superior to the one-step pyrolysis conducted at 600 ℃ for 5 min, which decreased the values to 32.2 area% and 11.2 wt%, respectively. The CO 2 introduction into N 2 atmosphere in stepwise pyrolysis further enhanced the hydrocarbon-rich bio-oil production, and a maximum bio-oil yield of 15.9 wt% was obtained in 100 vol% CO 2 , while the highest hydrocarbons selectivity of 51.8 area% was reached in 80 vol% CO 2. This work confirmed the advantages of stepwise pyrolysis for producing high-quality bio-oils and provided a reference for pyrolysis in CO 2 atmosphere. [ABSTRACT FROM AUTHOR]

[Display omitted] • The locust leaves-derived biochar coupled with Cu x O composites were synthesized by a facile hydrothermal method. • The as-prepared Cu x O@C catalysts have better CO 2 adsorption capacity and larger specific area compared to pure Cu x O catalyst. • The Cu x O@C-2 sample exhibited superior faraday efficiency of C 2 H 4 and excellent stability. • This work provides an advanced idea for the fabrication of efficient Cu-based catalysts and the utilization of biochar for CO 2 RR. The electrochemical CO 2 reduction reaction (CO 2 RR) to obtain high-valued product is considered to be a promising strategy for greenhouse effect mitigation. However, the development of low-cost electrocatalysts with excellent electrocatalytic performance is necessary. In this study, we developed a serials of locust leaves-derived Cu x O@C composites with large surface area and high CO 2 adsorption ability. Among them, the Cu x O@C-2 with optimal C content (0.10 g) displays the highest F E C 2 H 4 of 41.3 % at −1.08 V vs. RHE, which is 1.7 times higher than that of pure Cu x O sample. The enhanced performance for CO 2 RR may be attributed to the large BET surface area, improved adsorption ability of CO 2 and exposed abundant active sites. The work provides a feasible strategy for configuring Cu x O-based materials with high adsorption capacity and more reaction activity sites. [ABSTRACT FROM AUTHOR]

• The new spectral data of plasma-assisted biogas flames with varying CO 2 content are proposed. • Emission intensities of IR emitters are weakest at the ignition point but highest at the flame top. • The increase of CO 2 content by 20 vol% in the gas decrease emission intensities up to 10%. • The plasma assisted combustion leads to increased emission intensities at the burner nozzle up to 13%. • H 2 O* emission intensity in UV–VIS range linearly correlates with CO 2 emission intensity in MIR range. • Predictions of the flame temperature by spectral data presented. This complex study focuses on the effect of CO 2 level (40–80 vol% of CO 2 in CH 4) in biogas to radiative flame characteristics and the influence of plasma assistance on them at different fuel equivalence ratios. During experimental studies, the spectrometric characteristics of the flame at different heights (0, 25, 50 mm) were analysed to investigate radiative properties by UV–VIS and MIR spectrometers and the influence of the plasma-assisted combustion. The data obtained by infrared spectrometer indicated that the emission intensities of emitters are weakest at the ignition point of the mixture while the highest concentrations of emitters in the mid-IR range (1800–5800 nm) are formed in the upper part of the flame contrary to UV–VIS data. The increase of CO 2 content by 20 vol% in the mixtures led to decreased emission intensities up to 10 % for emitters in the range 2300 to 3500 nm and only 4–10 % for CO 2 emitter at 4450 nm. The plasma assisted combustion improves combustion stability of mixtures with CO 2 dilution and ensures flammability of the mixture with 80 vol% of CO 2 in CH 4. In general, plasma leads to increased emission intensities of CO 2 and H 2 O emitters at the burner nozzle from 13 to 11 % changing CO 2 dilution from 40 to 60 vol%. Approaching to leaner combustion regime, from ϕ = 0.71 to 0.63, the plasma effect is more intense and the intensity of emitters increases by 18–22 % compared to the case without plasma assistance. Correlations between UV–VIS and MIR data were determined and predictions of the flame temperature were proposed as well. [ABSTRACT FROM AUTHOR]

• The proposed model can be used for IFTs and MMPs prediction in nanopores. • Critical properties shift dominates IFT and MMP reduction over capillary pressure. • IFTs and MMPs become less sensitive to pore size when the pore radius exceeds 15 nm. • Mixing rule is more reasonable for MMP prediction in a real reservoir. CO 2 miscible flooding is considered to be a cost-effective and efficient method for improving shale oil recovery. The minimum miscibility pressure (MMP) between CO 2 and shale oil in nanopores is a crucial parameter for assessing the viability of miscible flooding. Experimental methods are often inadequate for capturing phase transition behaviors at the nanoscale. Therefore, it is essential to establish a comprehensive theoretical model to explore the phase behavior and miscibility of fluids confined in nanopores. Besides, the real shale formations have highly heterogeneous pore spaces, where the effect of pore size distribution on the MMP prediction should be properly addressed. In this research, a thermodynamic model that accounts for the nano-confinement effect is proposed to describe the interfacial tensions (IFTs) and MMPs profiles based on the vanishing interfacial tension (VIT) method. Firstly, a modified Peng-Robinson equation of state (PR-EOS) was employed for the vapor–liquid equilibrium (VLE) calculations at the nanopores by considering the capillary pressure effect and critical properties shift. Secondly, the model validation and the effect of temperature, pore radius, alkane type, and injected gas components on IFTs and MMPs were launched to analyze the nano-confinement effect. Finally, the model was applied to real shale oil to explore how pore size distribution affected the MMP in nanopores. The simulation results show that IFTs and MMPs calculated by the proposed model match very well with the experimental and molecular dynamic simulation (MD) results. The critical properties shift is the main cause for IFT and MMP reduction compared with capillary pressure. The MMPs of CO 2 -alkanes initially increase and then decrease with increasing temperature in nanopores. The IFTs and MMPs increase with pore radius, carbon number of alkanes. However, the IFTs and MMPs become less sensitive to pore size when the pore radius exceeds 15 nm. Higher C 2 H 6 & C 3 H 8 mole fractions decrease the MMP of confined fluids, while higher CH 4 mole fraction increases MMP. The MMPs calculated by considering the pore size distribution are lower than those calculated using the average pore radius. Therefore, the mixing rule should be considered when the pore size distribution is provided. We hope this model can give a more precise depiction of fluid phase behaviors in shale reservoirs, thereby facilitating the development of shale oil. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atom-planting method introduces three Ga species in MWW zeolite. • Ga-OH is more active for ethane dehydrogenation and tandem RWGS reaction. • Pt-Ga bimetallic catalyst is active for RWGS reaction in tandem with the EDH. Ga-loaded MWW zeolite catalysts with MWW topology was synthesized by atom-planting through dehydrochlorination of deborated ERB-1 and hydroxyl groups in GaCl 3 , and further loaded with Pt by ion exchange method for ethane direct dehydrogenation (EDH) and CO 2 oxidative dehydrogenation (CO 2 -ODH) of ethane. The atom-planting introduced GaCl 3 generated zeolite framework Si(OH)Ga, extra-framework Ga-OH species and Ga 2 O 3 in synthesized catalysts. And the extra-framework Ga-OH species showed higher ethane dehydrogenation activity compared with the Ga 2 O 3 species, while the Brönsted acid sites of framework Si(OH)Ga species could further convert the pruduced ethylene to aromatics. The Ga-OH species prepared by atom-planting generate [GaH]2+ and [GaH 2 ]+ during CO 2 -ODH reaction, which have better ability to activate CO 2 and has good activity for reverse water gas shift reaction as tandem reaction to promote the ethane dehydrogenation. The electron transfer between Pt and Ga 2 O 3 made the Pt-Ga bimetallic catalyst show good dehydrogenation activity and stability in the EDH and CO 2 -ODH reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu modification to VO x /Silicalite-1 for PDH-CO 2. • Improved dispersion of VO x and tuned acidic/basic sites. • Promoted reverse water gas shift. • Highest conversion of propane/CO 2 on 0.5Cu-10VO x /S-1. Propane dehydrogenation in CO 2 atmosphere (PDH-CO 2) is of interest with a potential to raise propane conversion. Here the catalytic performance of Cu modified 10VO x /Silicalite-1(S-1) for PDH-CO 2 is presented for the first time. The initial propane conversion of 68.8% on 0.5Cu-10VO x /S-1 was reached from 59.3% on 10VO x /S-1, along with the CO 2 conversion of 44.5% from 32.4%. The role of S-1 support and Cu modification were elucidated by means of X-ray diffraction (XRD), ultraviolet–visible diffuse reflection (UV–Vis), NH 3 /CO 2 temperature-programmed desorption (NH 3 /CO 2 -TPD), H 2 temperature-programmed reduction (H 2 -TPR) and X-ray photoelectron spectroscopy (XPS) characterization. While dispersing VO x , non-acidic S-1 minimized the side reactions usually occurring on the strong acidic sites. Cu modification promoted the dispersion of VO x and enabled 10VO x /S-1 exposing more weak acidic sites and basic sites, boosting respectively the adsorption of propane and CO 2 , for concurrently accelerating the reverse water gas shift (RWGS). Moreover, the highly dispersed V5+ was formed on the surface whereas the percentage of inactive V3+ decreased. [ABSTRACT FROM AUTHOR]

The adsorbed and dissolved oil in the shale reservoirs can be produced during CO 2 injection. However, the effects of different factors on the adsorption and dissolution behaviors of CO 2 and oil mixtures in the shale were unclear, such as the oil composition, shale properties and temperature. In this study, a series of adsorption and dissolution tests of CO 2 and different n-alkane mixtures in organic-rich shales were performed under different condition. The effects of the alkane type, shale properties and temperature on the adsorption and dissolution amount of mixtures and the replace ability of CO 2 to n-alkane were discussed, respectively. The results indicate that the dissolution amount was decreased with the chain length of alkane and increased with TOC and temperature. The adsorption amount of the mixtures in shale was low and only account for 3–16% of total adsorption and dissolution amount, which mainly depended on the specific surface area of the shale samples. Additionally, the replace ability of CO 2 to dissolved n-alkane was decreased with the chain length of alkane and temperature. However, there are no obvious rules between the replace ability with TOC of shale. This study can provide useful information for EOR of shale oil reservoirs by CO 2 injection and the geological storage of CO 2 in shale oil reservoir. [ABSTRACT FROM AUTHOR]

• Catalytic system reaction conditions are mild. • The bifunctional imidazolium ionic liquids are environmentally friendly and do not contain metals and halogens. • The bifunctional imidazolium ionic liquids show high catalytic efficiency to cyclic carbonates. • No additional organic solvents and cocatalysts are needed. The bifunctional imidazolium ionic liquids ([HEMim][Glu], [HEMim][Asp], [HEBim][Asp], [HEBim][Ala], [HEBim][His]) were successfully synthesized and characterized by 1H NMR, 13C NMR, COSY, HSQC and FT-IR spectroscopy. The ionic liquids performed as bifunctional catalysts and exhibited high catalytic activity for the cyclic carbonate synthesis from CO 2 and epoxides under mild conditions with excellent yields in the absence of any solvents or co-catalysts. The reaction time, reaction temperature, CO 2 pressure and the amount of ionic liquid were systematically investigated. The catalyst can be reused for at least four cycles without any significant drop in the catalyst activity and hence represents a reasonably environmentally benign chemical process for CO 2 fixation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Study the effects of temperature and dissolved carbon dioxide on the rheological response of bitumen. • Model the flow properties of the bitumen-CO 2 mixture while CO 2 is at its liquid and supercritical states. • Measure the discursivity of CO 2 in the bitumen-CO 2 mixture using the pressure-decay experiment coupled with rheometry. Abstract Carbon dioxide (CO 2) sequestration in depleted reservoirs is a practical solution to mitigate the emission of greenhouse gases. In financial considerations of the CO 2 sequestration projects, CO 2 can be considered as a solvent which can mobilize stranded oils underground. In this paper, we apply our novel high-pressure rheometry coupled with the pressure-decay technique, developed in our previous studies, to precisely determine the viscosities and mutual diffusivities for mixtures of bitumen with CO 2 at the temperature range of 30 °C–110 °C and at pressures as high as 10 MPa, where CO 2 is in liquid or supercritical forms. The developed novel technique overcomes the shortcomings of the pressure decay method by significant reduction in the experimentation time and eliminating uncertainties in determining the equilibrium pressure values. The reduced variable model is successfully adopted to describe the effects of temperature, pressure and CO 2 concentration on the viscosity of the mixtures. The viscosity data for the mixtures show a continuous drop regardless of the state of CO 2. Unlike the viscosity values, the diffusivity of CO 2 into the bitumen is dependent on the state and pressure of CO 2. The diffusivity values increase with temperature which are well described by the Arrhenius equation. While pressure had a significant effect on the diffusivity values in the gaseous state, shown in our previous study, the diffusivity values are less sensitive to pressure in the liquid and supercritical forms. It is also found that liquid CO 2 has the highest diffusivity in bitumen compared to supercritical and gaseous CO 2. The diffusivity values were compared to the few data in the literature for pressures above 10 MPa for CO 2 -bitumen mixtures. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract In this work, we probed the physical and chemical alteration of the carbonate-rich Utica Shale following CO 2 exposure when thin films of water were present at the shale surface. All reaction conditions were examined at 40 °C and CO 2 pressures up to 10.3 MPa for 14 days. CO 2 dissolution in the water layer at 2342 cm−1 and carbonate dissolution and precipitation at 1424, 874, and 712 cm−1 were discerned with in-situ Fourier Transform infrared spectroscopy (FT-IR). Significant etching and pitting from exposure to CO 2 and water were observed with feature relocation scanning electron microscopy (SEM). Application of the density function theory (DFT) for pore size analysis showed that micropores between approximately 0.9 and 2 nm disappeared while the mesopore volume increased after dissolution of carbonate. These results may provide new insights that carbonate rich shales such as the Utica may have a greater potential for alterations of pore space due to the reactivity of CO 2 which may affect 1) how CO 2 storage in shale formations plays a role in Carbon Capture and Storage (CCS) activities, 2) if CO 2 can be utilized as a potential fracturing agent, and 3) whether CO 2 is an effective fluid for enhanced hydrocarbon extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • NO x conversion of CeO x -biochar was dropped from 96.9% to 40.8% by the action of CO 2 at 200 °C. • The fast SCR reaction was hindered by CO 2 via inhibiting the oxidation of NO into NO 2. • CO 2 hindered NO x adsorption but improved NH 3 adsorption on the catalyst surface. • CO 2 were mainly adsorbed on the surface of CeO 2 to form carbonates and bicarbonates. • Carbonates and bicarbonates blocked the formation of active intermediates for NH 3 -SCR reaction. Low-temperature NH 3 -SCR of NO x technology was recognized as a promising way to control NO x emissions from industrial kilns at low temperatures. Except for SO 2 and H 2 O, lots of CO 2 exist in the flue gas of industrial kilns. However, there are few researches on the effects of CO 2 on the low-temperature NH 3 -SCR activity. To investigate the effects of CO 2 on the low-temperature NH 3 -SCR performance and mechanism of CeO x -biochar catalyst, a series of experiments employed. The results showed that the presence of CO 2 had an obvious inhibitory effect on the NH 3 -SCR performance of CeO x -biochar 0.6 at 150 °C. There was competitive adsorption between CO 2 and NO on the surface of CeO x -biochar 0.6. CO 2 was mainly adsorbed on CeO 2 , which hindered the oxidation of NO and the adsorption of NO x on the catalyst surface. Meanwhile, although the presence of CO 2 could improve NH 3 adsorption capacity of CeO x -biochar 0.6 due to the formation of NH 4 HCO 3 and (NH 4) 2 CO 3 , the existence of carbonates and bicarbonates blocked the formation of active intermediates NH 4 NO 2 and NH 2 NO for NH 3 -SCR reaction. As a result, the NO x conversion of CeO x -biochar 0.6 was dropped from 96.9% to 40.8% at 200 °C. In view of the bicarbonate and carbonate species was unstable at high temperatures, the inhibitory effect of CO 2 on NH 3 -SCR reaction was gradually weakened with the increase of reaction temperature. The NH 3 -SCR activity of CeO x -biochar 0.6 was seldom affected by CO 2 at 300 °C. Finally, a CO 2 poisoning mechanism for NO x removal by NH 3 -SCR at low temperature was proposed. [ABSTRACT FROM AUTHOR]

• Exhaust gas CO 2 absorption (EGCA) system was installed on MW-scale marine engine. • EGCA performance was certified as per the test procedure described in NTC 2008. • 29/30 wt%(E2/E3 mode) of CO 2 absorption was obtained by EGCA system. • Pretreatment reactor needs to be combined for stable operation of EGCA system. The management of CO 2 emissions from fossil fuel-powered ships has been considered for complying with future enhancements in CO 2 emission regulations in the shipbuilding industry. These regulations are (or will be) enforced using indexes such as the energy efficiency design index, energy efficiency existing index, energy efficiency operational indicator, and carbon intensity indicator. Hence, developing technology for reducing CO 2 emissions from ships is necessary. This paper reports on the CO 2 absorption performance of a pilot-scale CO 2 capture system installed on a 1.075-MW HiMSEN 5H22CDF engine. The proposed technology is an exhaust gas CO 2 absorption (EGCA) system. Our CO 2 capture system is based on an exhaust gas cleaning system, which is already commercialized to reduce SO x emissions from ships that use heavy fuel oil. The CO 2 absorption performance of the EGCA system was evaluated following the test procedure described in the NO x Technical Code 2008 (NTC 2008). Under the certified test procedure described in NTC 2008, the EGCA system exhibited 29/30 wt% (E2/E3 test mode) of CO 2 absorption. On the basis of the test results, we expect that ships will be able to comply with future CO 2 emission regulations by using the proposed EGCA system. [ABSTRACT FROM AUTHOR]

• 400 h of co-electrolysis at 300 mA/cm2 was carried out in different water. • The volatile components from seawater will not affect the electrode reaction. • The loss and agglomeration of Ni may be the causes of fuel electrode degradation. Solid oxide electrolysis cell (SOEC) for CO 2 /H 2 O co-electrolysis is an advanced technology that converts excessive power into synthesis gas. The products from CO 2 /H 2 O electrolysis can be used to synthesize liquid fuels, which are easy to store and transport. This work compared the electrolytic performances of syngas preparation in CO 2 /seawater and CO 2 /deionized water atmospheres using a flat-tube SOEC. The results showed that there was no significant difference in the instantaneous performance and the stability of the cells when electrolyzed in a CO 2 /seawater atmosphere and a CO 2 /deionized water atmosphere. The voltage degradation rate of the cell in the CO 2 /seawater atmosphere was about 5.38%/kh with an operating time of nearly 400 h and a current density of 300 mA/cm2; the degradation rate of the cell in CO 2 /deionized water atmosphere was about 7.37%/kh with an operating time of nearly 400 h and current density of 300 mA/cm2. The microstructure characterization results showed that the degradation of the electrolytic cells under the two atmospheres might be caused by the agglomeration and loss of Ni particles, and the volatile components from seawater would not diffuse to the fuel electrode near the electrolyte and affect the electrode reaction. [ABSTRACT FROM AUTHOR]

The global annual energy demand continues to rise at a rate that requires the use of all energy sources. Most nations have agreed to curb global warming by incentivizing the use of renewable sources and pursuing greenhouse gas recycling. Biomass is a carbon-neutral renewable source of energy as it releases, during burning and absorbs, during photosynthesis, identical amounts of CO 2. Oxidation of biomass with simultaneous deoxidation of CO 2 provides an accelerated path to its recycling into useful liquids and solids. This paper involves gasification of sodium aluminate impregnated corn stover char with simultaneous deoxidation of CO 2 in a fixed bed reactor. Future industrial adoption will be promoted by the use of a cost-effective impregnation methods. Particle sizes relevant to industrial gasifiers (< 75 μ m) were employed. Temperatures within the range 1060 K and 1210 K and pressures within the range 1.3 atm and 5 atm were examined. The impregnated char samples were studied using X=Ray Fluorescence (XRF) and Scanning Electron Microscope (SEM) to understand the transport and reaction processes involved in CO 2 gasification. The char exhibits needle-shaped structures that explain the enhancement in the gasification rate. The results showed that increasing pressure increases the gasification rate at temperatures within the 1210 K to 1060 K range. An increase in pressure from 1.3 atm to 5 atm results in a 150 K reduction (1210 K to 1060 K) in the gasification temperature necessary for an 85% char conversion. • Increases in pressure at the temperatures tested, lead to higher peak CO mole fraction. • Gasification rates are kinetically controlled for the temperatures tested. • Pressure increase allows for temperature decrease while maintaining reaction rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption energy of CO 2 in different crystalline forms of MgO was investigated by MD simulations. • The adsorption performance of CO 2 in different crystalline MgO under different process parameters was experimentally investigated. • The machine learning model predicted the adsorption energy based on salient features and analyzed the degree of contribution of each variable. The effects of the adsorption energy of CO 2 within MgO at different temperatures were investigated by molecular dynamics simulations and experimentally verified. The adsorption mechanism of CO 2 within MgO was discussed and explained qualitatively. The results indicated that the diffusive adsorption of CO 2 by MgO was divided into two stages, and the ability of CO 2 capture by the cubic MgO performed better than that by spherical MgO. The adsorption of CO 2 by the cubic MgO was mainly physical and received the inhibited adsorption behavior at the high-temperature stage (>505 K). Herein, we established a comprehensive dataset of adsorption energies and quantitatively analyzed an adsorption energy prediction model using machine learning techniques. The results demonstrated that Decision Tree Regression (DTR) and K-nearest neighbor (KNN) algorithms offer satisfactory accuracy based on root mean square error (RMSE) and R2 evaluations. This approach enables efficient and precise prediction of adsorption energies without the need for labor-intensive molecular dynamics calculations. Furthermore, we explored the influence of various features (Crystal structure, The number of Mg, The number of CO 2 , Temperature, Pressure, Volume, and Bond energy) on prediction performance. Lastly, we globally evaluated the relative contributions of each feature across four sets of relatively effective algorithms. This comprehensive analysis enhances our understanding of the adsorption mechanism of magnesium oxide on carbon dioxide and provides valuable insights to guide the design of the next generation of high-performance magnesium oxide materials for carbon capture and storage. [ABSTRACT FROM AUTHOR]

• Effects of polyether surfactants on decreasing IFT and improving oil–gas miscibility are investigated. • The mechanism of polyether on IFT and MMP has been explored by molecular dynamic simulations. • C 4 (PO) 6 has the best effect to decrease the IFT and MMP of CO 2 and shale oil. • Polyether can diffuse from CO 2 to the interface and oil phase to decrease the IFT and MMP. • Polyether can decrease the interaction energy by the dispersion force and LA-LB interactions. The successful application of CO 2 in developing shale oil can increase oil production and reduce CO 2 emission. Reducing IFT and facilitating miscibility between CO 2 and oil is the critical mechanism for enhancing shale oil recovery by CO 2 flooding. Here, the effects of alkyl block polyethers on the interfacial tension and minimum miscibility pressure of CO 2 and shale oil has been investigated by experiments and the influence mechanism of polyether on IFT and MMP has been explored by molecular dynamic simulations. The experimental results show that among the three polyethers, C 4 (PO) 6 has the best effect to decrease the IFT and MMP of CO 2 and shale oil. The IFT and MMP decrease with the increasing concentration of C 4 (PO) 6 in CO 2. The IFT and MMP can be decreased to a lower value when the polyether is dissolved in CO 2 than in oil phase. The molecular dynamic simulations show that polyether molecules can diffuse from CO 2 phase to the interface of CO 2 and oil to decrease the IFT and further diffuse to oil phase to accelerate the miscibility process of CO 2 and oil. The presence of polyether molecules can decrease the interaction energy, especially the vdW interactions between CO 2 and oil molecules to decrease the IFT and MMP. The reduction of interaction energy is due to the dispersion force and LA-LB interactions between polyether and CO 2 , as well as the dispersion force interactions between polyether and oil molecules. The finding is significant to the chemical design for decreasing the IFT and MMP of CO 2 and oil and further to successfully and efficiently develop shale oil by the CO 2 -surfactant mixed fluid. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous medium adhesion oil film model for simulating the steam flows through the heavy oil reservoir. • Innovative study of the oil film's effects on steam condensation and heat transfer in porous media. • Lab experiments for long-distance steam heat transfer and oil film dynamic stripping by composite hot fluid. The CO 2 and Sodium Dodecyl Sulfate (SDS) assisted steam flooding technology was an effective approach addressed the persistent issues that have hindered the stable development of high-viscosity cold oil through steam injection. However, in the process of steam flow through porous media, the synergistic influence of the oil film adsorbed in near wellbore porous media, and the CO 2 -SDS on steam heat transfer has not been investigated. Steam heat transfer is the key factors affecting heavy oil recovery. The primary objective of this study was to research the effect of CO 2 -SDS on steam heat transfer and oil film stripping by designing experiments. The study results demonstrated that in the initial stage of displacement, the heat transfer resistance between the steam and the porous medium was increased by the oil film adsorbed in near wellbore area. In additional, the condensation mode of the steam was altered from bead condensing to film condensing by the composite thermal fluid flooding, preventing the steam heat dissipation near wellbore area and transferring more thermal to the long-distance area. At the later stage of displacement, the interfacial tension between oil-water and oil-gas was reduced by CO 2 -SDS, improving the fluidity of oil and providing the seepage channel for steam, and increasing the steam thermal sweep range. Compared to the sandpack experiment of steam flooding, the temperature at the output end of the sandpack model increased from 69.8 °C to 88.7 °C, indicating an expansion of the steam heat sweep range and successful long-distance heat transfer during composite thermal fluid flooding. In the process of composite thermal fluid flooding, the maximum displacement pressure difference increased from 2.28 MPa to 3.07 MPa, and the maximum oil recovery rate increased from 2.48 g/mL to 2.81 g/mL. The peak of the high production period was raised, resulting in a 40.97% to 51.86% increase in recovery rates. [ABSTRACT FROM AUTHOR]

• The surface charge of Saudi basalt rock sample is controlled by the protonation of the silanol group and the electrical double-layer effect. • The Saudi Basalt rock is negatively charged in freshwater and seawater environments. • The colloidal stability of the rock is compromised in cases of seawater and the presence of MgCO 3 and FeCO 3 precipitates. • The MgCO 3 and FeCO 3 precipitation controls the pH of the system. Global concern over climate change caused by greenhouse gas emissions has received and is still receiving a lot of attention. Companies and nations have committed to reducing their carbon footprint to halt the consequences, and work is being done to create long-term strategies for CO 2 usage. One of these goals is to use the CO 2 that has been captured to make chemicals or to use it to make waste that can be buried or safely disposed of. One such endeavours is CO 2 mineralization, which has been suggested as a method of CO 2 utilization. It entails the creation of carbonates by the interaction of a fluid that contains CO 2 with cations that are found in brines or rocks. However, the mineralization process is a protracted one, and until recently it was not believed that it could be completed in less than two years. Furthermore, little research has been done on how mineralization affects the electrokinetic and surface chemistry of cation-bearing rocks like basaltic rocks. Therefore, this study assesses how mineralization (carbonate precipitation) affects the colloidal and electrokinetic characteristics of basaltic rock. According to the study's findings, the electrical double layer (EDL) effect and protonation of the silanol group function as the two main controlling mechanisms of charge formation in the basaltic rock. More so, the rock sample is negatively charged over a range of pH and colloidally stable in freshwater. However, its colloidal stability is decreased in brines, and the EDL effect and potential determining ions (H+ and OH–) dominate its charge development. Additionally, different precipitates have distinct effects on the electrokinetic characteristics of basaltic rock, with the MgCO 3 and FeCO 3 precipitation having a more notable impact than the CaCO 3 precipitation. Furthermore, at pH values of 3 – 4 (CO 2 storage pH) in both freshwater and sweater environments, basaltic rocks exhibit near zero or low surface charge values indicating weak adhesion force. Thus, the question of if the near pH values of 2, can be considered as higher values of surface charge is observed in some cases. These findings raise questions about the structural integrity of basaltic rock, which has been touted as a prime candidate for the mineralization process due to its reactive nature, particularly in the case of colloidal stability after the mineralization process. The results of this study further provide new insight into the optimization of the mineralization process, which is dependent on the structural and petrophysical characteristics of the rocks and reservoirs that provide the cations for the process. [ABSTRACT FROM AUTHOR]

Highlights • Catalytic oxidation of lignite by O 2 can highly yield oxygen-contained chemicals (OCC). • Application of methanol in NaVO 3 -H 2 SO 4 aq. system can suppress CO 2 generation. • Acetalization of aldehydes and esterification of carboxyls by ethanol protect them to CO 2. • OCC yield increases from 24.2% to 42.5% by adding 30 vol.% methanol. • The application of methanol can substantially improve the utilization of carbon in lignite. Abstract The production of oxygen-containing chemicals (OCCs) from lignite via catalytic oxidation with O 2 is an effective method. However, in the process, a significant amount of CO 2 is generated, reducing the utilization of carbon. To suppress CO 2 production, we introduced methanol into the NaVO 3 -H 2 SO 4 aqueous solution to produce OCCs from lignite. The yields of OCCs (mainly including carboxylic acids, methyl formate, and methylal) and CO 2 are 42.5% and 26.8%, respectively, at a methanol content of 30 vol.%, while these in NaVO 3 -H 2 SO 4 aqueous solution are 24.2% and 56.3%, respectively. We also found that methylal is produced via the acetalization between methanol and aldehyde, and the reaction changes the pathway of aldehyde conversion into carboxyl. Meanwhile, ester is generated via esterification between methanol and carboxyl group, protected against decarboxylation to CO 2. These acetalization and esterification suppress CO 2 generation. Introducing methanol into NaVO 3 -H 2 SO 4 aqueous solution improves the utilization of carbon in lignite significantly. [ABSTRACT FROM AUTHOR]

Highlights • Three multicomponent gasoline surrogates containing diisobutylene were constructed. • The ignition delay of the surrogates was measured under different conditions. • A chemical kinetic model for gasoline surrogates was generated and validated. • Flux and sensitivity analyses were performed to study the effects of condition parameters. Abstract Two quaternary and one quinary surrogates containing diisobutylene are constructed according to the characteristics of gasoline with a research octane number of 95. The ignition delay measurements for all three surrogates are performed in a high-pressure shock tube at pressures of 10/15/20 bar, equivalence ratios of 0.5/1.0/2.0, in the temperature range of 950–1300 K with exhaust gas recirculation loadings ranging from 0% to 60%. A chemical kinetic model composed of 563 species and 2915 reactions is generated to describe the ignition features of gasoline surrogates. It is validated by numerous experimental data of ignition delay for isooctane, n-heptane, toluene, diisobutylene, cyclohexane and their mixtures with the comparison of other proposed chemical mechanisms in the literature. Satisfactory agreement is obtained between the measurements and simulated data for all three surrogates, which illustrates the negative correlation of temperature, pressure and equivalence ratio with ignition delay, and the inhibitive effects of EGR on the system reactivity. Moreover, the sensitivity, reaction flux and rate of production analyses, and the history of reactive radicals are explored with different temperatures, pressures, equivalence ratios and EGR rates. The results reveal the remarkable dependence of ignition delay on the temperature than other parameters and indicate the predominant dilution and thermal effects of CO 2 on the ignition of the quinary gasoline surrogate. [ABSTRACT FROM AUTHOR]

Highlights • Outbursts were fabricated due to the rate of gas decompression. • Coal briquettes and CO 2 were used by a designed experimental apparatus. • Major energy of outbursts is from the free state gas in coal briquettes. • Evolution of outbursts was observed and analysed. Abstract The coal and gas outburst has become a worldwide challenge and is still not fully understood. In this study, an experimental investigation was carried out for outburst evolution. Coal briquettes were fabricated based on less than 0.6 mm pulverized coal particles of Tunliu Coal Mine. CO 2 was used to simulate outbursts by saturating coal briquettes in varying gas pressures (0.2, 0.4 and 0.6 MPa). The outbursts of coal briquettes were induced when rapid gas decompression was performed. The results indicate the outbursts depend on the gas pressure, water content and the rate of gas decompression. The differential pressure between the gas inside and outside the coal briquette is essential to outbursts and varies for different water contents while other parameters affect the initiation and intensity of outbursts as well. The higher gas pressure the more intense outburst occurs. It is worth noting that low rate of gas decompression cannot activate any outburst in the experiments even for a high gas pressure. The water content affects the outburst strongly. The critical minimum gas pressure in the coal briquettes with high water content becomes much higher than that in the coal briquettes with low water content. The major energy of the outbursts in the experiments is the expansion energy of the free state gas inside the coal briquettes. This study clearly demonstrates the progressive fragmentation of outbursts due to gas decompression. [ABSTRACT FROM AUTHOR]

Highlights • A model for sorption dynamics of hydrocarbons and carbon dioxide in shale. • It accounts for molecular-scale to continuum-scale parameters in shale. • The proposed model is used to assess the adsorption of CO 2 in presence of CH 4. • Sorption efficiency of CO 2 component in presence of CH 4 is assessed. Abstract Evidence from experimental studies related to sorption on nanoporous materials, coals, and most recently on shales suggests that the sorption of gas in these targets is not instantaneous, i.e. the time it takes for the gas to adsorb to its maximum capacity is not negligible. A recent experimental study showed that the sorption in shale rocks is non-instantaneous, i.e. there is a delayed effect in adsorption due to different mechanisms of sorption in different materials of shale, for e.g. in inorganic and organic matter. The current suite of models used to predict sorption in shale (e.g. Langmuir, BET, etc.) assumes an instantaneous equilibrium, which is not justifiable for sorption in shales. Sorption of hydrocarbons and carbon dioxide in shale stratum is a complex mechanism that is affected by micro-scale affinity between the adsorbent-adsorbate, pore-scale heterogeneity of the surface with respect to the pore distribution, and structural heterogeneity of the system. These multi-phenomena effects are multi-scale in nature, and their impact on sorption cannot be predicted using simple models that assume instantaneous equilibrium. A model for reliable prediction of sorption in shales must take into account above discussed effects. This study proposes a mechanistic model for multi-scale sorption dynamics (referred as "MSSD") in shale that accounts for molecular and pore-scale effects, in addition to the continuum-scale effects, by corresponding parameters that are relevant on those scales. Proposed model is validated against three experimental datasets that depict sorption dynamics in shale. The MSSD model is then used to investigate the efficiency of carbon storage in shale by adsorption when it is injected as a binary mixture with methane. The proposed model makes it convenient to study the effects of molecular-scale to continuum-scale parameters on sorption in shale that are otherwise possible only through expensive means of experiments or molecular dynamic simulations. [ABSTRACT FROM AUTHOR]

• CO 2 reacts with methyl groups to both promote and inhibit combustion. • CO 2 is weakly oxidizing and can participate in chemical reactions. • CO 2 also reacts with formaldehyde, ethylene and vinyl. The study aims to examine the impact of CO 2 concentration gradient on the ignition and combustion of a diesel surrogate fuel composed of 70% C 7 H 16 and 30% C 7 H 8. The investigation focuses on the weak oxidation of CO 2 through its reaction with methyl groups (CH, CH 2 , and CH 3 radicals). Firstly, the molecular bond-breaking recombination process between CO 2 and methyl groups is calculated using Born-Oppenheimer molecular dynamics with the UB3LYP/6–311++g (d, p) level of theory. Subsequently, the electronic distribution and competition of the molecule surface are analyzed through various wave function analyses to identify the reactive sites. Secondly, the precise potential energy surface and reaction rate are calculated based on the acquired reaction process information. This calculation employs the B2PLYP/def2-TZVP level of theory and transition state theory. Finally, extensive molecular dynamics simulations of CO 2 and methyl groups are conducted using reaction force fields. These simulations provide insights into the temperature-energy variation within the system and the resulting chemical reaction network. The optimized combustion mechanism for the binary fuel is derived, focusing exclusively on the influences of CO 2 and O 2 while excluding those of N 2 and other extraneous gases. The results demonstrate exothermic reactions of CO 2 with CH and CH 2 radicals at 850 K, yielding ΔG values of −238.91 kJ/mol and −209.96 kJ/mol, respectively. Conversely, CO 2 reacts with CH 3 radicals in heat-absorbing reactions at 850 K, resulting in a ΔG of 491.73 kJ/mol. Additionally, the chemical impact of CO 2 exhibits both promotional and inhibitory effects on combustion. The CO 2 molecule exhibits weak oxidation properties due to the presence of active sites on its surface characterized by minimal values of electrostatic potential (-50.17 kJ/mol) and average local ionization energy (61.92 kJ/mol) at the O-atomic end. The molecular dynamics process involving the methyl groups and CO 2 system exhibits a heat absorption phenomenon. This behavior can be attributed to the participation of CO 2 not only in the reactions with methyl groups but also with formaldehyde and ethylene, among others. [ABSTRACT FROM AUTHOR]

• The adsorption and diffusion of CO 2 in pyrophyllite slit pores are investigated. • Interlayer water can increase the adsorption amount of CO 2 in pyrophyllite when the water content is less than 30 wt%. • Water can inhibit CO 2 diffusion in pyrophyllite slits. • CO 2 is mainly adsorbed on the pore surface of pyrophyllite in parallel configuration. Understanding the microscopic process of adsorption and diffusion of CO 2 in clay minerals is important for geological storage of CO 2. In this study, Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) simulations are used to obtain the adsorption and diffusion behavior of CO 2 in pyrophyllite slit pores. The influence of split pore size, temperature, pressure, and water content were analyzed in detail. The adsorption characteristics of CO 2 in pyrophyllite were revealed by discussing the distribution of CO 2 density profile, adsorption capacity, isosteric heat of adsorption, interaction energy, mean square displacement, self-diffusion coefficient, and molecular orientation distribution. It shows that the excess adsorption isotherm of CO 2 in pyrophyllite slit pores demonstrate significant supercritical adsorption characteristics. Surface attractions originating from both pore walls overlap in the middle of pore, leading to an enhanced adsorption capacity of CO 2 in pyrophyllite slit pores when pore aperture is lower than 3 nm. In pyrophyllite pores, the presence of water has an enhancing effect on CO 2 adsorption when the water content is below 30 wt%. A maximum value of CO 2 adsorption amount is reached at the water content of 10 wt%, while negative growth occurs at 35 wt%. At low water content, water molecules form a weak adsorption layer due to the weak attraction of pyrophyllite to water. As water content increases, the self-diffusion coefficient of the CO 2 decreases, and the diffusion capacity decreases. The adsorption state of the CO 2 molecule on the mineral surface is primarily a parallel configuration, while the water molecule has no clear orientation. Our calculated results can provide guidance for further study of clay-water-adsorbate interface reaction of hydrophobic minerals. [ABSTRACT FROM AUTHOR]

• CFD simulation of CO 2 methanation in a shell-and-tube reactor was performed. • A conjugated heat transfer solver was developed using OpenFOAM. • The VOF model was implemented for phase change of the water on the shell side. • A large catalyst heat conductivity facilitates heat transfer to the shell side. • Using boiling water can effectively reduce the coolant flow rate. This paper reports a computational fluid dynamics simulation of carbon dioxide (CO 2) methanation via the Sabatier process in a shell-and-tube reactor, incorporating a water phase change simulation on the shell side using the volume of fluid (VOF) method. The essential heat removal factors and their mechanisms, such as the catalyst size, bed porosity, thermal conductivity, coolant flow rate, and coolant boiling, were primarily investigated. The computational code was a newly developed in-house version of ChtMultiRegionFOAM based on OpenFOAM v2006. This code can simulate catalyst-gas heat transfer, which is called the two-temperature model. The code was extended to new methanation and phase-change models based on the VOF method. The computational code was first validated using existing experimental data. After sufficient accuracy was confirmed, several parametric studies were conducted. Catalyst heat conductivity was the most influential factor among the catalyst-related parameters. The flow rate of the oil coolant significantly affected the cooling performance. Finally, the use of boiling water significantly reduced the coolant flow rate. Moreover, the cooling performance remained unchanged until the total heat release rate from the gas exceeded the total latent heat of the water. [ABSTRACT FROM AUTHOR]

• A novel evaluation method for the CO 2 mineral storage potential in basalts was established which considers two injection scenarios including direct CO 2 injection and carbonated water injection. • The distribution and geological conditions of terrestrial basalts in China were investigated, and the CO 2 mineral storage capacities in different regions were calculated by Monte Carlo method. • The effective mineral storage capacities for direct CO 2 injection and carbonated water injection are 847.95Gt and 249.50Gt, respectively, and the C eff are 0.0181 and 5.31 × 10-3, respectively, at P 50. • The matching of carbon sources and sinks, and the prospect of the CO 2 storage demonstration projects in basalts of China were discussed. Basalts contain a lot of carbon-fixing minerals which can achieve the fast mineral trapping of CO 2. Based on the CO 2 mineral trapping mechanism, an evaluation method for CO 2 storage capacity in basalts was established, which considers two injection scenarios including direct CO 2 injection and carbonated water injection. Then the geological conditions of terrestrial basalts in China were assessed. The range of CO 2 mineral storage capacity in basalts at different probabilities was calculated by Monte Carlo simulation. The results show that the total theoretical mineral storage capacity of CO 2 in the terrestrial basalts of China is 39792.05–54325.44 Gt with an average of 46948.36 Gt (P 50). The effective mineral storage capacities for direct CO 2 injection and carbonated water injection are 607.79–1121.44 Gt (P 50 = 847.95 Gt) and 201.13–303.85Gt (P 50 = 249.50 Gt), respectively. The corresponding effective storage coefficients at P 50 are 0.0181 and 5.31 × 10-3, respectively. Carbonated water injection is advised for prior use, which can achieve CO 2 mineral trapping more rapidly. The effective storage capacity is usually much larger than the CO 2 emissions in the same region except for the eastern region, but their distributions are not well matched, needing a comprehensive source-sink optimization. The screening and classification of basalts in China should also be strengthened in the future to promote the utilization of CO 2 mineral storage capacity and the implementation of demonstration projects. [ABSTRACT FROM AUTHOR]

• Bubble point pressure of crude oil decreases with increasing H 2 S content. • The higher the H 2 S concentration, the lower the MMP between sour gas and crude oil. • Increasing H 2 S concentration delays gas breakthrough and improves oil recovery. • Presence of high permeable zones in a reservoir leads to early gas breakthrough. Proper handling of the produced sour gas is a big challenge for operating companies due to the serious environmental and technical problems caused by H 2 S and CO 2. The reinjection of the produced sour gas into oil reservoirs is an environmentally friendly as well as an economically attractive method due to the low investment cost and incremental oil recovery. However, the sour gas injection for enhanced oil recovery (EOR) is a relatively new approach with numerous uncovered perspectives, especially in a heterogeneous reservoir. The objective of this study is to investigate the effect of gas composition and reservoir heterogeneity on the miscible displacement of reservoir oil using sour gas. The reservoir oil consisting of 15 mol% H 2 S and 4 mol% CO 2 from an oilfield in the North Caspian region was used. First, the phase behavior alteration of reservoir oil due to the injection of various gases, namely H 2 S, CO 2 , CH 4 , acid, and sour gas was analyzed. Then, the effect of gas type on minimum miscibility pressure (MMP) was investigated based on a semi-analytical tie-line method. Moreover, 2D and 3D numerical simulations were conducted to understand the oil recovery performance of various gas injection options and the effect of permeability heterogeneity on sour gas flooding efficiency. The findings showed that higher H 2 S content in the injected gas narrows the two-phase envelope and decreases the bubble point pressure. Moreover, it was observed that MMP decreases with increasing H 2 S concentration, which provides a favorable condition for achieving miscibility. Additionally, an increase in H 2 S concentration in sour gas improves its oil recovery efficiency by extending gas breakthrough time and elongating the plateau period of oil rate. These results are useful for designing, optimizing, and implementing sour gas injection for EOR in oil reservoirs that have access to sour gas sources. [ABSTRACT FROM AUTHOR]

[Display omitted] • The quasi-SMILES are employed to represent the DESs. • CO 2 absorbing capacity is predicted using Quasi-SMILES. • The QSPR models developed with CII are more robust and significant. • The fragments and conditions for better absorption of CO 2 are identified. • Consensus modelling was done to improve the robustness of QSPR models. The interpretation of the CO 2 capture capacity of the deep eutectic solvents (DESs) as a mathematical function of (i) hydrogen bond acceptor(HBA); (ii) hydrogen bond donor (HBD); (iii) Molar ratio (HBA: HBD) (iv) temperature in kelvin and (v) p (MPa) gives quantitative models with good statistical quality. The quasi-SMILES are employed to represent the DESs (deep eutectic solvents under different conditions) for building up QSPR models. Quasi-SMILES differ from regular SMILES (simplified molecular input-line entry system) by including extra characters that indicate experimental parameters. SMILES descriptors may be used to construct quantitative structure–property/activity relationships (QSPRs/QSARs), whilst quasi-SMILES descriptors can be employed to build quantitative models of laboratory findings under diverse situations. Four random splits are prepared from the dataset of 72 DESs and each split is further divided into four sets namely active training, passive training, calibration and validation set. The percentage of the common quasi-SMILES in a set of two splits is zero. Three target functions with and without the index of ideality of correlation (IIC) and correlation intensity index (CII) are applied to build 12 QSPR models. The statistical quality of present QSPR models (mCO 2) developed by the third target function is good to excellent, with determination coefficients ranging from 0.8303 to 0.9206 for the external validation set. In the last, consensus modelling using the intelligent consensus tool of DTC lab (https://dtclab.webs.com/software-tools) is also performed to predict the robustness of the developed models. The distribution of the dataset of all splits is applied to generate different consensus models and in all cases, the consensus model is found winner. The determination coefficient of all winner consensus models was in the range of 0.9751 to 0.9910 ( C M 0 Split 1 R 2 = 0.9909 ; C M 0 Split 2 R 2 = 0.9883 ; C M 2 Split 3 R 2 = 0.9910 ; and C M 3 Split 4 R 2 = 0.9751). The statistical results of the determination coefficient and MAE (95%) of the second consensus model of split 3 ( C M 2 Split 3 R 2 = 0.9910 ; C M 2 Split 3 M A E 95 % = 0.17776) was found best than the R2 and MAE (95%) of other consensus models of all splits. Therefore, it was considered as a winner consensus model from all consensus models. [ABSTRACT FROM AUTHOR]