ABSTRACT When CO 2 is sequestered in deep aquifers of sedimentary basins, mudstone or shale is usually used as a caprock. When the caprock contains low‐permeability basalt interlayers, its sealing potential could be improved. This study utilized geological data from the Jianghan Basin in central China to establish a generalized two‐dimensional reactive transport model to investigate the sealing potential of basalt as an interlayer in the mudstone caprock. The reactions of CO 2 with the minerals in the basalt interlayer are critical to its sealing performance. On the one hand, CO 2 mineralization sequesters a portion of the CO 2 that enters the caprock, thereby reducing the amount of free CO 2 there. On the other hand—and more importantly—mineral precipitation reduces the porosity of the basalt interlayer by up to 48%, triggering a self‐sealing effect impeding upward CO 2 migration in the caprock. Fresh or weakly altered basalt interlayers containing olivine and pyroxene have a strong sealing capability. When the basalt is completely altered (excluding olivine and pyroxene), its sealing performance is significantly compromised. A basalt interlayer with a permeability in the range of 10 −16 –10 −17 m 2 can effectively impede the upward migration of CO 2 . Even when the basalt interlayer is very thin (only 1 m), a mudstone caprock containing it exhibits superior sealing performance relative to one without a basalt interlayer. Furthermore, the closer the basalt interlayer is to the base of the mudstone caprock, the greater its sealing performance.
ABSTRACT CO 2 mineralization of alkaline solid wastes enables permanent CO 2 sequestration and the production of cementitious materials. However, the inherently low reactivity of these wastes limits their practical application. This study systematically investigates the impact of CO 2 mineralization on steel slag's cementitious activity and develops targeted enhancement strategies. By constructing a comprehensive database integrating experimental and literature data, we employed XGBoost‐based machine learning to quantitatively evaluate reactivity‐limiting factors. Key findings reveal that while CO 2 mineralization minimally directly enhances reactivity, it critically improves slag stability and mitigates risks from trace elements. Subsequent thermodynamic and kinetic studies identified mechanochemical milling and aluminate incorporation as effective methods for boosting slag reactivity. To improve slag performance, we recommend optimizing particle size to ≤ 20 µm, applying magnetic separation to limit iron content to ≤ 30 wt%, and integrating mechanochemical milling for enhanced activation.
ABSTRACT To mitigate the greenhouse effect, promoting the clean utilization of fossil fuels and advancing carbon capture, utilization, and storage (CCUS) technologies have become critical pathways. Among these approaches, CO 2 and CH 4 flooding, as key enhanced oil recovery (EOR) techniques, exhibit dual benefits in both emission reduction and production enhancement. In this study, molecular dynamics simulations are employed to systematically investigate the oil displacement behaviors of CO 2 and CH 4 in porous media reservoirs. Simulations are conducted under two temperature conditions: 300 K (ambient temperature) and 383 K (elevated temperature). The heat and mass transfer characteristics, as well as multiphase interaction mechanisms, are comparatively analyzed under three injection scenarios: CO 2 single flooding, CH 4 single flooding, and alternating CO 2 ‐CH 4 injection. The results indicate that CO 2 single flooding at 383 K achieves the highest molecular displacement fraction; however, it is accompanied by pronounced gas channeling. In contrast, under ambient temperature conditions (300 K), alternating injection exhibits significant synergistic effects. In particular, the alternating flooding strategy initiated with CO 2 injection enhances molecular displacement fractions while effectively suppressing gas channeling compared with single‐gas flooding. At elevated temperature, although alternating injection mitigates the risk of gas channeling, the increased gas diffusion coefficient weakens intermolecular interactions, leading to a reduced displacement efficiency relative to single‐phase flooding. By establishing a multidimensional analytical framework that integrates temperature distribution, molecular interactions, and reservoir adsorption characteristics, this study elucidates the intrinsic mechanisms governing gas migration under multi‐physical field coupling. The findings provide molecular‐scale theoretical insights for optimizing gas injection strategies in unconventional oil reservoirs.
ABSTRACT The urgent need to mitigate CO 2 emissions from fossil‐based industries necessitates the development of CO 2 separation solvents that combine high absorption capacity with low regeneration energy. The conventional monoethanolamine (MEA) solvent is widely used but limited by high regeneration energy constraint, equipment corrosion, and degradation. In this work, a novel biphasic solvent system comprising diethylenetriamine (DETA) and dimethylcyclohexylamine (DMCA) was proposed and thoroughly evaluated for post‐combustion CO 2 capture. The optimized formulation (DMCA:DETA = 3:2) achieved a high CO 2 loading capacity of ∼1.1 mol CO 2 /mol amine with spontaneous phase separation, producing a 70% CO 2 ‐rich phase. Selective regeneration of this rich phase reduced the total energy demand to 2.76 GJ/t CO 2 , representing ∼40% savings compared with 5 M MEA (4.34 GJ/t CO 2 ). Kinetic studies confirmed rapid absorption rates, whereas FTIR analysis demonstrated reversible carbamate formation and solvent stability across multiple absorption–desorption cycles. The reduced viscosity of the CO 2 ‐rich phase further improved prospects for the chosen solvent. These outcomes established the DETA–DMCA biphasic system as a durable, energy‐efficient, and scalable solvent for next‐generation CO 2 capture, offering significant potential for deployment in industrial flue gas treatment.
ABSTRACT The injection stage of the CO 2 storage process presents distinct technical challenges, primarily in managing multiphase flow dynamics. A comprehensive understanding of phase behavior and P – T effects is required to support efficient injection and optimal storage capacity. In this study, to maximize storage capacity, multiphase CO 2 injections were simulated in a low‐pressure depleted gas reservoir in the Musi Field of South Sumatra. The economic analysis evaluates two business models (storage‐as‐a‐service and carbon‐credit storage service), each assessed within three cooperation schemes (gross split, cost recovery, and public–private partnership), using key financial indicators including NPV, IRR, contractor and government take, and the cost of CO 2 storage. The simulation results indicate that CO 2 storage in depleted gas reservoirs can be optimized through a variable‐phase injection approach. Injection begins in the gas phase while the reservoir pressure remains low until it reaches the CO 2 bubble point. Subsequently, operators would inject dense‐phase CO 2 as the reservoir pressure increases. The injection strategy evaluates multiple wellhead pressure settings and identifies a pressure‐profile discontinuity characterized by a sudden increase in bottom‐hole pressure when the wellbore pressure crosses the CO 2 gas–liquid saturation boundary. With this variable‐phase injection management scenario, CO 2 storage of up to 67.4 million tons can be achieved in 33.4 years. The storage fees for PPP, cost recovery, and gross split schemes are $11.94, $12.58, and $14.32 per ton CO 2 , respectively. Carbon credit services follow suit with fees of $36.16, $35.82, and $43.39 per ton CO 2 under the same schemes.
Efficient purification and separation of biogas are the prerequisites and foundations for realizing the efficient utilization of biogas on a large scale. Unpurified biogas as well as the gas produced by the overall gasification combined cycle containing CO 2 , SO 2 , and other gas impurities, which will reduce the calorific value of biogas and aggravate environmental pollution. Biogas purification is possible using the hydrate technique of mixed gas separation technology. The formation–decomposition dynamics of mixed gas hydrates and the advancement of research on the mixed gas separation technology of their hydrate technique are thoroughly reviewed in this study, especially the selective hydrate formation of CH 4 containing gas mixtures and their gas separation properties. Highlighted are the quantitative impacts of various variables on the gas mixture hydrate formation process and its kinetic principles. On this basis, the influences of different driving forces, gas–liquid ratios, and gas components on the formation of gas mixture hydrates and their gas separation effects are detailed. Various factors’ regulatory mechanisms and ways of enhancing their effects on the formation of gas mixture hydrate and its gas separation process are described. Finally, the mechanism of the influence of hydrate selective formation on the separation characteristics of gas mixtures is analyzed in depth. Additionally, the challenges and future directions for the large‐scale application of hydrate‐based mixed gas separation technology were explored. It is noted that the key to achieving an effective purification and separation process of gas mixtures is the directional regulation of the selective hydrate formation process and the synergistic coupling of various reinforcing techniques. More in‐depth research is required in this field.
The long-term security of carbon dioxide geological storage (CGS) depends on pore structure evolution driven by CO2-water-rock interactions. Experiments were conducted under simulated reservoir conditions (36 degrees C, 7.2 MPa) using Ordos Basin sandstone as the reservoir rock and C30 cement as the sealing material. Pore and mineral evolution were characterized by nuclear magnetic resonance (NMR) T 2 spectra and x-ray diffraction (XRD). Sandstone exhibited a staged evolution following a dissolution-expansion -> precipitation-contraction -> dynamic equilibrium pattern: an initial expansion phase, where dissolution of reactive minerals (e.g., albite and illite) increased meso- and macropore volume, with porosity reaching a local maximum at approximately 16 h during the early expansion stage, followed by a contraction phase marked by mineral transformation (e.g., anorthite) and particle migration, leading to a dynamic dissolution-transformation balance. In contrast, cement maintained a stable microstructure dominated by micropores. These results indicate that early dissolution may temporarily enhance permeability and leakage risk, whereas subsequent precipitation promotes pore-throat clogging and structural self-sealing, improving long-term integrity. The study demonstrates that pore evolution is controlled by dissolution-precipitation cycles and that NMR T 2 spectra effectively capture these dynamics, providing an experimental basis for evaluating storage capacity and leakage risk in geological CO2 storage.
The reuse of decommissioned offshore platforms for geological carbon storage offers a cost-effective and technically feasible strategy to reduce greenhouse gas emissions in emerging economies. This study presents a comprehensive techno-economic assessment of offshore carbon capture and storage (CCS) hubs in Brazil, with a focus on the Merluza Field in the Santos Basin. A detailed cost model was developed to quantify capital expenditure (CAPEX), operational expenditure (OPEX), and the levelized cost of storage (LCOS) for scenarios involving infrastructure reutilization. Results indicate that site characterization dominates the cost structure, accounting for up to 76% of CAPEX in reuse scenarios, despite an overall 6% reduction in total capital investment when compared with new offshore construction. Annual OPEX is estimated at $7.79 million, and over a 40-year project lifespan, the net present value of operational costs reaches $104.68 million. The LCOS ranges from $12.72 to $35.54 per ton of CO2 for a 1.39 Mtpa case, making the Brazilian scenario economically competitive when compared to international benchmarks such as Sleipner and Quest. Moreover, potential revenues from carbon credits and avoided emission penalties could substantially offset total project costs. These findings highlight the financial viability of offshore CCS in Brazil and reinforce its potential integration into national decarbonization strategies under the Paris Agreement. 2026 Society of Chemical Industry and John Wiley & Sons, Ltd.
Syngas, a vital feedstock in the chemical industry, consists of hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and impurities such as hydrogen sulfide (H2S) and ammonia (NH3). Syngas is used in the production of ammonia, methanol, H2, and so forth. The impurities, such as H2S and CO2, are present in the syngas, which causes a decrease in the quality of syngas, and when H2S and CO2 are released into the air, they cause harm to the environment and contribute to global warming. In the research article, the syngas recovery process was modeled using Aspen Plus software and industrially validated. The Peng-Robson thermodynamic property method is used to simulate the process. The Peng-Robinson is used for hydrocarbons. The effect of the change of the number of distillation stages and the reflux ratio is studied to check the recovery of H2S and CO2 gas. The primary objective is to model and simulate the syngas recovery process. The second objective was to perform a parametric analysis of the process to investigate the effects of changing the number of distillation columns and reflux ratio, as well as studying the impacts of CO2 and H2S recovery and heat integration. In this analysis, the process stream of product steam is utilized to decrease the temperature of the feed stream. It reduced the utility cost of the inlet feed stream, resulting in a 0.03% decrease in cost. The third objective was to conduct a cost analysis of the process before the parametric analysis and the heat integration method to analyze the process's profit. This was due to the process recovering 1.06% H2S gas and 0.002% CO2, and calculating the utilities cost of the process. The fourth objective is an exergy analysis of the process in which the overall exergy destruction is 0.42%. The fifth objective was to use the simulation software ALOHA to model the dispersion of H2 gas. In the case, H2 gas is released into the air; it is a hazardous gas, destroying 1.2 mi. The proposed cryogenic approach achieves 85% CO2 removal, 99% H2S removal, and complete NH3 separation. Exergy analysis shows minimal energy losses, highlighting its advantages over solvent-based techniques. The cost estimate further supports the approach's feasibility, indicating lower operating costs. This study offers a comparative assessment of syngas separation methods, with insights into energy efficiency and economic viability.
To mitigate the greenhouse effect, promoting the clean utilization of fossil fuels and advancing carbon capture, utilization, and storage (CCUS) technologies have become critical pathways. Among these approaches, CO2 and CH4 flooding, as key enhanced oil recovery (EOR) techniques, exhibit dual benefits in both emission reduction and production enhancement. In this study, molecular dynamics simulations are employed to systematically investigate the oil displacement behaviors of CO2 and CH4 in porous media reservoirs. Simulations are conducted under two temperature conditions: 300 K (ambient temperature) and 383 K (elevated temperature). The heat and mass transfer characteristics, as well as multiphase interaction mechanisms, are comparatively analyzed under three injection scenarios: CO2 single flooding, CH4 single flooding, and alternating CO2-CH4 injection. The results indicate that CO2 single flooding at 383 K achieves the highest molecular displacement fraction; however, it is accompanied by pronounced gas channeling. In contrast, under ambient temperature conditions (300 K), alternating injection exhibits significant synergistic effects. In particular, the alternating flooding strategy initiated with CO2 injection enhances molecular displacement fractions while effectively suppressing gas channeling compared with single-gas flooding. At elevated temperature, although alternating injection mitigates the risk of gas channeling, the increased gas diffusion coefficient weakens intermolecular interactions, leading to a reduced displacement efficiency relative to single-phase flooding. By establishing a multidimensional analytical framework that integrates temperature distribution, molecular interactions, and reservoir adsorption characteristics, this study elucidates the intrinsic mechanisms governing gas migration under multi-physical field coupling. The findings provide molecular-scale theoretical insights for optimizing gas injection strategies in unconventional oil reservoirs.
CO2 compression and liquefaction are critical process in carbon capture, utilization, and storage (CCUS) systems. However, CO2 streams obtained from capture sources often contain impurities such as N2, O2, and H2O, which significantly alter the thermophysical properties of pure CO2 and pose considerable challenges for system design and operation. In this study, the Peng-Robinson equation of state was employed within the Aspen HYSYS process simulation platform to systematically investigate the effects and mechanisms of these typical impurities on CO2 throughout the processes of compression, liquefaction, and pipeline transportation. The results reveal the quantitative influence of impurities on the thermodynamic properties, pipeline characteristics, and compression performance of CO2. N2 and O2 decrease the critical temperature and increase the critical pressure of the CO2 mixture, whereas H2O exhibits the opposite effect. In terms of thermodynamic properties, the density of CO2 is more sensitive to pressure variation, whereas viscosity and thermal conductivity are more sensitive to impurity concentration. N2 and O2 exhibit similar effects, whereas the influence of H2O on viscosity and thermal conductivity is negligible. During pipeline transportation, the presence of impurities intensifies pressure loss and pressure drop, with H2O exerting the most significant influence, whereas temperature distribution is only slightly affected. In the compression process, N2 and O2 increase the compressibility factor of CO2 and shift the compression path to the right on the pressure-enthalpy (p-H) diagram, leading to a considerable rise in compression energy consumption. The total energy consumption increases with impurity concentration. This study provides a solid theoretical basis and valuable data support for the optimized design, safe operation, and economic performance of industrial processes involving CO2 mixtures containing impurities.
The integrity of wellbore cement needs to be maintained to ensure the effectiveness and stability of geological CO2 storage (GCS). However, the chemical instability of wellbore cement in CO2-rich environments poses a serious risk of CO2 leakage. This vulnerability arises from CO2-induced alteration of cement hydration products, leading to detrimental physicochemical changes in the cement matrix. This study examined the ability of biochar-modified wellbore cement to resist CO2 attack. The cement samples were initially cured in a 1 wt% NaCl solution for 14 days under the conditions of 17 MPa and 62 degrees C, mimicking deep downhole conditions. Afterward, the samples were completely immersed in an autoclave containing CO2-saturated brine solution, which was maintained under the same pressure and temperature conditions. To evaluate the feasibility of using biochar to mitigate CO2 alteration, microstructural and mineral composition changes in wellbore cement samples were characterized both before and after exposure to CO2 using various techniques, including XRF, micro-CT, and SEM-QEMSCAN. The characterization results indicate that adding biochar enhanced CO2 alteration resistance of the cement matrix. With the addition of 2% biochar, the carbonation depth was reduced to 556.1 & micro;m, compared to 594.7 & micro;m in the reference sample after CO2 exposure. In addition, BC-2 sample showed a smaller reduction in compressive strength (16.25% decrease after 28 days of CO2 exposure), indicating less degradation when exposed to CO2 compared to the RF sample (40.49% decrease after 28 days of CO2 exposure). In short, biochar exhibits moderate resistance to CO2 alteration and shows potential for application in wellbore cement systems to inhibit CO2 penetration.
The injection stage of the CO2 storage process presents distinct technical challenges, primarily in managing multiphase flow dynamics. A comprehensive understanding of phase behavior and P-T effects is required to support efficient injection and optimal storage capacity. In this study, to maximize storage capacity, multiphase CO2 injections were simulated in a low-pressure depleted gas reservoir in the Musi Field of South Sumatra. The economic analysis evaluates two business models (storage-as-a-service and carbon-credit storage service), each assessed within three cooperation schemes (gross split, cost recovery, and public-private partnership), using key financial indicators including NPV, IRR, contractor and government take, and the cost of CO2 storage. The simulation results indicate that CO2 storage in depleted gas reservoirs can be optimized through a variable-phase injection approach. Injection begins in the gas phase while the reservoir pressure remains low until it reaches the CO2 bubble point. Subsequently, operators would inject dense-phase CO2 as the reservoir pressure increases. The injection strategy evaluates multiple wellhead pressure settings and identifies a pressure-profile discontinuity characterized by a sudden increase in bottom-hole pressure when the wellbore pressure crosses the CO2 gas-liquid saturation boundary. With this variable-phase injection management scenario, CO2 storage of up to 67.4 million tons can be achieved in 33.4 years. The storage fees for PPP, cost recovery, and gross split schemes are $11.94, $12.58, and $14.32 per ton CO2, respectively. Carbon credit services follow suit with fees of $36.16, $35.82, and $43.39 per ton CO2 under the same schemes.
Accurate characterization of pore-structure parameters in digital rock images is critical for the reliable prediction of subsurface transport processes, including fluid flow in hydrocarbon reservoirs and geological CO2 storage formations. X-ray computed tomography (XCT) enables nondestructive 3D core imaging, but imaging noise degrades reconstruction accuracy and pore network authenticity. Existing research lacks in-depth analysis of denoising methods' correlation with pore parameters. This study evaluates XCT datasets of carbonate cores, using entropy, structural similarity index (SSIM), porosity, and fractal dimension to compare traditional denoising methods via 3D pore network modeling. Findings show denoising methods significantly affect porosity calculations: total and connected porosity peak relative differences reach 30.5% and 40.95%, respectively. Tortuosity and pore coordination number are notably impacted, whereas fractal dimension and equivalent pore radius are less affected. Dual-filter combinations outperform single filters, whereas combinations of three or more filters are not recommended due to excessive smoothing. Although denoising alters parameter values, it preserves the spatial variation trend of core properties, guiding researchers to balance accuracy and efficiency when selecting denoising strategies. This study provides theoretical guidance for scientific denoising algorithm selection in digital core construction, enhancing microscopic reservoir characterization credibility and promoting precise digital core applications in petroleum engineering.
Greenhouse gas emissions significantly contribute to global warming, highlighting the need for effective and sustainable carbon dioxide (CO2) capture technologies. This study introduces a hybrid carbon capture and storage (CCS) prototype that integrates mist-assisted absorption with coconut fiber adsorption as a low-cost and renewable approach. The system was evaluated in terms of CO2 capture efficiency and energy consumption. The prototype consists of four chambers: mist generation units to enhance gas-liquid contact and coconut fiber packing to adsorb residual CO2. Six experimental modes were tested at two gas flow velocities (0.9 and 1.4 m/s). Real-time CO2 monitoring was performed using NDIR MH-Z16 sensors validated against a reference probe meter, with data acquisition through the NI MyRIO platform. Results showed that capture efficiency increased from 14% to 19% in the baseline condition to a maximum of 65.9% in the hybrid configuration combining six mist modules and coconut fiber. Energy consumption analysis revealed that the energy consumption index (ECI) ranged from 72.95 to 79.85 kWh/kg CO2, with the lowest ECI obtained in the hybrid setup, although mist generation contributed significantly to power demand. Despite higher energy use compared with advanced chemical or vacuum swing adsorption systems, the prototype offers advantages in terms of simplicity, operational practicality, and use of renewable local resources. These findings demonstrate the potential of coconut fiber-based hybrid CCS systems as complementary solutions for decentralized and small-scale applications.
CO2 mineralization of alkaline solid wastes enables permanent CO2 sequestration and the production of cementitious materials. However, the inherently low reactivity of these wastes limits their practical application. This study systematically investigates the impact of CO2 mineralization on steel slag's cementitious activity and develops targeted enhancement strategies. By constructing a comprehensive database integrating experimental and literature data, we employed XGBoost-based machine learning to quantitatively evaluate reactivity-limiting factors. Key findings reveal that while CO2 mineralization minimally directly enhances reactivity, it critically improves slag stability and mitigates risks from trace elements. Subsequent thermodynamic and kinetic studies identified mechanochemical milling and aluminate incorporation as effective methods for boosting slag reactivity. To improve slag performance, we recommend optimizing particle size to <= 20 & micro;m, applying magnetic separation to limit iron content to <= 30 wt%, and integrating mechanochemical milling for enhanced activation.
Carbon capture, utilization, and storage (CCUS) is a key technology for enabling the large-scale, low-carbon utilization of fossil fuels. Scientific and rational source-sink matching is an important basis for site selection in CCUS cluster deployment projects. This study focuses on geological formations in North China, such as saline aquifers, coalfields, oil fields, and gas fields. First, it explores methods for assessing the CO2 geological storage potential of each formation type. Second, it discusses CCUS source-sink matching and pipeline network optimization methods based on the saving mileage method and the least-cost path method. Subsequently, it conducts source-sink matching research for CCUS cluster deployment in North China. Finally, it puts forward recommendations for the cluster deployment of CCUS in the region. The research findings indicate that over a 30-year planning horizon, the cumulative CO2 emissions from 16 large coal-fired power plants in North China are nearly 5.0 billion tons. The total geological storage potential for CO2 in the region is 16.0 billion tons, with saline aquifers offering a distinct storage advantage. After pipeline network optimization, saline aquifers, coal seams, and oil fields can store a total of 3.05 billion tons, 1.47 billion tons, and 0.48 billion tons of CO2, respectively. The optimized plan requires a cumulative planned pipeline length of 2399.5 km and a total investment of $299.97 billion. Compared to the initial plan, pipeline length and cumulative investment can be reduced by 39.83% and 13.64%, respectively. By utilizing the cost path analysis tool in ArcGIS, the impacts of factors such as terrain slope, land-use type, road traffic, and population density on the CCUS pipeline network layout can be comprehensively considered. The CCUS cluster deployment in North China can focus on regions such as those south of the Yin Mountains, east of the Taihang Mountains, south of the Yanshan Mountains, and the southern part of the Qinshui Basin. It is essential to fully leverage the advantages of saline aquifers. Demonstration projects should be established on a cluster basis to streamline the overall layout of the CCUS pipeline network. The study identified source-sink matching schemes that can integrate different regions: by connecting CO2 Emission Source No. 10 with No. 3, Storage Sink No. 8 with No. 4, and Storage Sink No. 1 with Emission Source No. 6, the various CCUS cluster deployment areas in North China can be integrated into a unified whole. This study provides theoretical support for the implementation of CCUS cluster deployment and demonstration projects in North China.
Hydrogen is a promising source of energy, given the current context of depletion of fossil fuels and increased emissions of greenhouse gases. The technological route for obtaining this fuel from the dry reforming of biogas has received considerable attention from researchers, as it converts the polluting gases CH4 and CO(2 )into synthesis gas (H-2 and CO). In this work, Ni-Al catalysts derived from hydrotalcite were modified with lithium through different methods and were tested in the biogas dry reforming. Coprecipitation, wet and dry impregnation methods were applied, as well as memory effect reconstruction. N-2 adsorption-desorption, XRD, TPR, CO2-TPD, SEM, and TPO techniques were used for the characterization of the catalysts. For the catalytic tests, a flow rate of 60% CH4 and 40% CO(2 )was used as synthetic biogas. The ramp tests were carried out in the range from 500 to 750 degrees C while the stability tests were carried out at 700 degrees C for 8 h. The results demonstrated that the different Li incorporation methods had a strong effect on the surface, structural and reduction properties of the obtained catalysts. The coprecipitated sample (CP) presented the best performance in the reaction, due to its smaller crystallite size, high basicity and presence of weak, medium and strong basic sites, while the worst results observed for the impregnated samples were attributed to the formation of the LiAlO2 phase in these samples, resulting in materials with low surface area and large crystallite size. The CP sample reached the highest CH4 conversion (54%) after 480 min of reaction and a low carbon formation rate.
Ongoing carbon dioxide (CO2) buildup in the environment aggravates the Earth's planet, leading to climate change and environmental issues. The post-combustion carbon capture via physical adsorption using an adsorbent is an effective treatment for capturing CO2. Aspen Adsorption is an optimistic design tool for gas adsorption in a fixed-bed capture unit. Aspen Adsorption is widely applied for simulating and optimizing fixed-bed adsorption processes, providing an effective platform for designing and evaluating CO2 capture systems. In this study, the adsorption-based fixed-bed capture unit is developed for CO2 capture using Aspen Adsorption. Three different adsorbents are derived from three classes of biomass materials: (i) coconut shell, (ii) rice husk, and (iii) eucalyptus wood. The characteristics of the developed adsorbents are analyzed and studied. The adsorbents' performance is evaluated in the fixed-bed adsorption system to examine CO2 and N2 adsorption efficiencies. A critical parameter on the main operating conditions, surface textural features, and dimensions of the capture unit, namely, (i) adsorption and desorption temperature and pressure, (ii) adsorbent materials' surface textural characteristics and physicochemical properties, and (iii) adsorption column dimensions, is considered for the adsorption study. Overall, 60% CO2 and 40% N2 gas compositions are employed as the inlet gas stream. The adsorbents' adsorption efficiency and parameters are evaluated and discussed. The simulation results indicate a maximum CO2 recovery rate of 68% and a CO2 purity of 97%. Approximately 5.0 GJ/t of CO2 is the energy consumption required for regeneration.
Reliable characterization of mineralogical and textural changes in rock samples is essential for understanding fluid-rock interactions, particularly in experimental studies simulating subsurface conditions. This study presents a reproducible protocol for scanning electron microscopy (SEM) analysis of rock surfaces before and after exposure to CO2 under controlled temperature and pressure conditions. The protocol enables the precise relocation of observation areas, allowing a direct comparison of microstructural features such as mineral dissolution, secondary precipitation and porosity evolution. Combining SEM with digital image analysis and expert petrographic interpretation, the method enhances the repeatability and quantitative rigor of comparative studies. The complete experimental workflow (from sample preparation to post-exposure imaging) is described in detail, emphasizing the importance of spatial referencing and surface preservation. The protocol is demonstrated through a case study involving detrital sandstone samples from the Middle Eocene of the Ebro Basin (Spain), representing potential reservoir rocks. Samples were exposed to supercritical CO2 under controlled conditions (8 MPa, 40 degrees C, 30 days), either dry or in contact with CO2-saturated brine. Results show that brine-mediated CO2 exposure led to selective mineral dissolution, grain detachment and increased porosity, indicating relatively high geochemical reactivity. In contrast, dry CO2 exposure caused minimal alteration, suggesting that fluid presence is critical for chemical interaction. The proposed protocol enables detailed discrete-time surface characterization and provides a robust framework for evaluating rock-CO2 interactions in geological storage settings.
