Specific Surface Area Pore Research Articles

Impact of micromechanical properties of organic matter on the micro-mesopore structures of the over-mature shale in the Niutitang Formation

The micromechanical properties of organic matter (OM) and organic pore structures in the over-mature stage are crucial for determining shale reservoir quality and assessing shale gas resource potential. However, there is still debate about the influence of micromechanical properties of OM on the micro-mesopore structures in over-mature shale. In this study, shale cores from the Niutitang Formation have been specifically chosen for OM isolation, adsorption testing, atomic force microscopy examination, and focused ion beam scanning electron microscopy (FIB-SEM) analysis to assess the micromechanical properties of OM and pore structures. The findings indicate that organic micropores and mesopores predominantly exhibit elliptical, circular, or irregular shapes. Organic pores mainly provide pore volume (PV) and specific surface area (SSA) of shale. In the over-mature stage, residual kerogen and pyrobitumen transition towards a graphite structure, increasing Young’s modulus of OM. Additionally, as thermal maturity increases, the absence of a rigid mineral framework and pore fluid pressure results in the compaction of pores, leading to a decrease in PV and SSA. The organic micropores are more vulnerable to collapse and compaction because of the increased brittleness of OM. The organic micropores and mesopores gradually evolve from regular circular and elliptical shapes to irregular shapes during the over-mature stage. The research findings provide valuable insights into the micromechanical mechanism of pore evolution in over-mature marine shale within complex structural regions.

Influence and Mechanism of Structural Characteristics of Limestone on Quicklime Reaction Activity

Quicklime (CaO) is extensively used in metallurgy, chemical engineering, materials science, and greenhouse gas reduction due to its high reactivity, low energy consumption, and environmental benefits. It is considered as one of the most promising raw materials for nanomaterial synthesis and carbon dioxide capture. Previous studies have predominantly focused on the impact of limestone composition and calcination condition. Recent research, however, suggests that the structural characteristics of limestone also play a crucial role in determining the reactivity of quicklime. This study investigates the effect of limestone structure on quicklime reactivity and provides a mechanistic analysis. Three types of limestone with varying structures—clastic-structured, transitional-crystalline-structured, and crystalline-structured—were selected for experiments under different calcination times. The results indicate that quicklime produced from clastic-structured limestone exhibits the highest reactivity. The observed differences in quicklime reactivity can primarily be attributed to the following factors: (1) Clastic-structured limestone possesses larger pore volume and specific surface area, which enhance heat conduction and ensure the uniform decomposition of calcite across various regions. (2) The rock-forming calcite particles are fine and small, allowing for the simultaneous decomposition of the outer shell, middle, and core during heating. This prevents “overburning” of the shell or “underfiring” of the core, thereby improving the overall reactivity. Based on these findings, we propose that fine-grained, high-purity clastic-structured limestone is more favorable for producing high-activity quicklime.

Catalytic Effects of Different Metal Salts on Cotton Waste Textiles by Pyrolysis: Pyrolysis Behavior and Properties of Activated Carbon

This study was conducted to explore the catalytic effects of different metal salts on the pyrolysis behavior of cotton waste textiles (CWTs) and the properties of their activated carbons (ACs). The decomposition characteristics of CWTs with Zn, Fe, and Cu salts were studied by thermogravimetric analysis (TGA) to analyze the catalytic effects. The physical and chemical characteristic differences of the ACs were detected with SEM-EDS, BET, FTIR, and XPS. The results show that metal salts reduced the decomposition temperature of the CWTs and improved the pore structures and specific surface areas of the activated carbons (ACs). The ACs produced abundant acidic surface functional groups on their surfaces, which facilitated the selective adsorption of pollutants. This study indicates that cotton waste textile biochar treated with metal salts may be a promising adsorbent for the removal of heavy metals and organic pollutants.

Three-dimensional bioprinting utilizing sacrificial material support and longitudinal printability evaluation through volumetric imaging.

In three-dimensional (3D) bioprinting, the internal channel network is vital for nutrient and oxygen transport, crucial for cell survival and tissue construction. However, bioinks' poor mechanical properties hinder precise control over these networks. Advancements in 3D printing strategies, structure characterization, and deformation monitoring can improve hydrogel scaffolds with interconnected channels. Using label-free, non-invasive, in-situ optical coherence tomography (OCT) imaging, we monitored the dynamic deformation of 3D bioprinted hydrogel scaffolds. We validated sacrificial materials' role in enhancing internal channels and introduced deformation characteristics, lateral pore ratio and pore-specific surface area as new parameters. Results from cell-laden hydrogels show that 3D bioprinting with sacrificial materials achieves high fidelity, minimizing collapse, inter-filament fusion, and enhancing lateral porosity. Furthermore, these promote cell proliferation and cell viability.

Characterization, adsorption kinetic and in vitro release behavior of curcumin loaded with porous mannitol and porous lactose: Template agent method vs. Pore-forming agent method.

Polyvinylpyrrolidone K30 was used as the templating agent, and ammonium bicarbonate was used as the pore-forming agent to make porous mannitol and porous lactose by the template and pore-forming agent method, respectively. Compared with the template method, the porous particles prepared by the pore-forming agent method have larger pore diameter (320.276nm and 250.528nm) and specific surface area (1.018m2/g and 0.913m2/g). The molecular docking results showed that mannitol/lactose interacted with curcumin and adhered to each other through hydrogen bonding. The adsorption kinetics process of porous mannitol and porous lactose prepared by template agent, pore-forming agent and curcumin were different. Among the curcumin-loaded porous particles prepared by the two methods, the curcumin-loaded porous lactose prepared by the pore-forming agent method had the fastest release rate and the highest cumulative release rate (95%). Curcumin releases consistent with the Peppas release kinetics model and the diffusion mechanism.

Experimental investigation and ReaxFF simulation on pore structure evolution mechanism during coalification of coal macromolecules in different ranks

This analysis revealed the alterations in the pore structure of large organic molecules in coal during the process of coal pyrolysis. Nine models of macromolecular structures in coals, representing distinct coal ranks, have been built. The research results show that along with the increasing coal rank, the average microporous volume of medium rank coal is 0.0287 cm3/g. The average microporous volume of high-grade coal is 0.0662 cm3/g. The micropore volume and specific surface area of coal samples decrease in the order of high rank, low rank, and middle coal. The experimental measurements align with the ReaxFF pyrolysis simulation calculations, indicating a decrease in the hydrogen to carbon ratio and oxygen to carbon ratio of all coal molecules. Additionally, the pore volume and specific surface area exhibit a pattern of initially decreasing and then increasing. The simulation results of gas probes indicate that a majority of the pores with a diameter larger than that of CH4 molecules are found in the macromolecular structure models of low rank coal and medium to high rank coal. The conclusions are useful for us to understand the formation and development process of pores in coal reservoir. A two-dimensional representation of coal’s macromolecular structure was constructed using ChemDraw software. The Forcite module in Materials Studio software was used to perform geometric optimization and annealing kinetics simulation of a two-dimensional macromolecular structure model. The ReaxFF-MD module in Amsterdam Modeling Suite (AMS) 2020 software to model the pyrolysis of XJ coal macromolecules.

Quantifying the Pore Characteristics and Heterogeneity of the Lower Cambrian Black Shale in the Deep-Water Region, South China.

Recently, significant breakthroughs have been made in the exploration of shale gas in the Lower Cambrian black shale of the Sichuan Basin, indicating a promising commercial extraction potential. However, there remains considerable controversy regarding the pore structural characteristics for this shale formation, especially in the deep-water region. To address this, this paper focused on core samples from two shale gas wells (Xa1 and Xb1) located in the slope-basin facies zone during the Early Cambrian. The analysis involved X-ray diffraction (XRD) analysis, microscopic imaging, and N2-CO2 adsorption-desorption experiments to qualitatively and quantitatively characterize the pore structural characteristics, pore size distribution, and pore types in the deep-water region. The results show that Niutitang shales can be classified into four lithofacies based on mineral composition: siliceous shale, muddy siliceous shale, mixed siliceous shale, and siliceous calcareous shale. Meanwhile, the black shale exhibits diverse pore types, predominantly organic pores, along with significant development of interparticle pores, intraparticle pores, intercrystalline pores, and a few microfractures. In the Niutitang Formation shale of deep-water regions, mesopores contribute the most to the pore volume, followed by macropores, exceeding 89%. Micropores contribute the most to the specific surface area, followed by mesopores, accounting for more than 98%. Each lithofacies shale displays a similar multipeaked distribution pattern, with siliceous shale generally having the most significant pore volume and specific surface area and the highest heterogeneity. Notably, the total organic carbon (TOC) content is the primary factor controlling the micropore structure of the Niutitang Formation shale in the study area, with a less significant impact on mesopores and macropores. Siliceous shale, which has a high average TOC content of 9.58 wt %, exhibits the greatest pore volume and specific surface area. Quartz contributes to the development of micropores in the shale of the study area, whereas clay minerals somewhat inhibit pore development. Overall, the mineral composition has a minor impact on pore development. These findings provide theoretical support for the evaluation of deep shale gas reservoirs and the prediction of favorable areas in the Lower Cambrian Niutitang Formation in Western Hunan.

Effects of the Hot-Drawing Process on the Pore Parameters, Gas Absorption and Mechanical Performances of Activated Carbon-Loaded Porous Poly(m-Phenylene Isophthalamide) Composite Fibres.

Poor breathability, inadequate flexibility, bulky wearability, and insufficient gas-adsorption capacity always limit the developments and applications of conventional chemical protective clothing (CPC). To create a lightweight, breathable, and flexible fabric with a high gas-absorption capacity, activated carbon (AC)-loaded poly(m-phenylene isophthalamide) (PMIA) porous composite fibres were fabricated from a mixed wet-spinning process integrated with a solvent-free phase separation process. By manipulating the pore parameters of as-spun composite fibres, the exposure-immobilization of AC particles on the fibre surface can offer a higher gas-absorption capacity and better AC-loading stability. To improve the mechanical properties of AC-loaded porous as-spun fibres and further optimize the pore-locking structures, the impact of the hot-drawing process on the evolution of pore parameters and the corresponding properties (including the gas absorption capacity, the mechanical performance, and the stability of AC particles during loading) was clarified. After the hot-drawing process, the inhomogeneous pore morphologies composed of mesopores/micropores from as-spun fibres changed into homogeneous and decreased mesopores. With the decrease in structural defects in homogeneous morphologies, the tensile strength of AC-loaded PMIA porous-drawn fibres increased to 1.5 cN/dtex. Meanwhile, the greater total pore volume and specific surface area after hot drawing also maintained the gas-absorption capacity of drawn composite fibres at 98.53 mg/g. Furthermore, the AC-loaded PMIA porous composite fibres also showed comparable performance to the commercial FFF02 absorption layer in terms of static absorption behaviour for different gas molecules and absorption-desorption multi-cycling evaluations. In addition, due to the size reduction in mesopores after the hot-drawing process, the loading stability of AC particles in the stretched composite fibres was more substantial.

Multiscale Qualitative–Quantitative Characterization of the Pore Structure in Coal-Bearing Reservoirs of the Yan’an Formation in the Longdong Area, Ordos Basin

Accurate characterization of coal reservoir micro- and nanopores is crucial in evaluating coalbed methane storage and gas production capacity. In this work, 12 coal-bearing rock samples from the Jurassic Yan’an Formation, Longdong area, Ordos Basin were taken as research objects, and micro- and nanopore structures were characterized via scanning electron microscopy, high-pressure mercury pressure, low-temperature N2 adsorption and low-pressure CO2 adsorption experiments. The main factors controlling coal pore structure development and the influence of pore development on the gas content were studied by combining the reflectivity of specular samples from the research area, the pore microscopic composition and the pore gas content determined through industrial analyses and isothermal absorption experiments. The results show that the coal strata of the Yan’an coal mine are a very important gas source, and that the coal strata of the Yan’an Formation in the study area exhibit remarkable organic and clay mineral pore development accompanied by clear microfractures and clay mineral interlayer joints, which together optimize the coal gas storage conditions and form efficient microseepage pathways for gas. Coalstone, carbonaceous mudstone and mudstone show differential distributions in pore volume and specific surface area. The general trend is that coal rock is the best, carbonaceous mudstone is the second best, and mudstone is the weakest. The coal samples’ microporous properties are positively correlated with the coal sample composition for the specular group, whereas there is no clear correlation for the inert group. An increase in the moisture content of the air-dried matrix promotes adsorption pore development, leading to increases in the microporous volume and specific surface area. CH4 adsorption in coal rock increases with increasing pressure, and the average maximum adsorption is approximately 8.13 m3/t. The limit of the amount of methane adsorbed by the coal samples, VL, is positively correlated with the pore volume and specific surface area, indicating that the larger the pore volume is, the greater the amount of gas that can be adsorbed by the coal samples, and the larger the specific surface area is, the greater the amount of methane that can be adsorbed by the coal samples. The PL value, pore volume and specific surface area are not correlated, indicating that there is no direct mathematical relationship between them.

Investigation of Coal Structure and Its Differential Pore–Fracture Response Mechanisms in the Changning Block

The deep coal seams in the southern Sichuan region contain abundant coalbed methane resources. Determining the characteristics and distribution patterns of coal structures in this study area, and analyzing their impact on pore and fracture structures within coal reservoirs, holds substantial theoretical and practical significance for advancing coal structure characterization methods and the efficient development of deep coalbed methane resources. This paper quantitatively characterizes coal structures through coal core observations utilizing the Geological Strength Index (GSI) and integrates logging responses from different coal structures to develop a quantitative coal structure characterization model based on logging curves. This model predicts the spatial distribution of coal structures, while nitrogen adsorption data are used to analyze the development of pores and fractures in different coal structures, providing a quantitative theoretical basis for accurately characterizing deep coal seam features. Results indicate that density, gamma, acoustic, and caliper logging are particularly sensitive to coal structure variations and that performing multiple linear regression on logging data significantly enhances the accuracy of coal structure identification. According to the model proposed in this paper, primary-fragmented structures dominate the main coal seams in the study area, followed by fragmented structures. Micropores and small pores predominantly contribute to the volume and specific surface area of the coal samples, with both pore volume and specific surface area increasing alongside the degree of coal fragmentation. Additionally, the fragmentation of coal structures generates more micropores, enhancing pore volume and suggesting that tectonic coal has a greater adsorption capacity. This study combines theoretical analysis with experimental findings to construct a coal structure characterization model for deep coal seams, refining the limitations of logging techniques in accurately representing deep coal structures. This research provides theoretical and practical value for coal seam drilling, fracturing, and reservoir evaluation in the southern Sichuan region.

Gas Content and Geological Control of Deep Jurassic Coalbed Methane in Baijiahai Uplift, Junggar Basin

Deep coalbed methane (CBM) resources are abundant in China, and in the last few years, the country’s search for and extraction of CBM have intensified, progressively moving from shallow to deep strata and from high-rank coal to medium- and low-rank coal. On the other hand, little is known about the gas content features of deep coal reservoirs in the eastern Junggar Basin, especially with regard to the gas content and the factors that affect it. Based on data from CBM drilling, logging, and seismic surveys, this study focuses on the gas content of Baijiahai Uplift’s primary Jurassic coal seams through experiments on the microscopic components of coal, industrial analysis, isothermal adsorption, low-temperature CO2, low-temperature N2, and high-pressure mercury injection. A systematic investigation of the controlling factors, including the depth, thickness, and quality of the coal seam and pore structure; tectonics; and lithology and thickness of the roof, was conducted. The results indicate that the Xishanyao Formation in the Baijiahai Uplift usually has a larger gas content than that in the Badaowan Formation, with the Xishanyao Formation showing that free gas and adsorbed gas coexist, while the Badaowan Formation primarily consists of adsorbed gas. The coal seams in the Baijiahai Uplift are generally deep and thick, and the coal samples from the Xishanyao and Badawan formations have a high vitrinite content, which contributes to their strong gas generation capacity. Additionally, low moisture and ash contents enhance the adsorption capacity of the coal seams, facilitating the storage of CBM. The pore-specific surface area of the coal samples is primarily provided by micropores, which is beneficial for CBM adsorption. Furthermore, a fault connecting the Carboniferous and Permian systems (C-P) developed in the northeastern part of the Baijiahai Uplift allows gas to migrate into the Xishanyao and Badaowan formations, resulting in a higher gas content in the coal seams. The roof lithology is predominantly mudstone with significant thickness, effectively reducing the dissipation of coalbed methane and promoting its accumulation.

Comparative study on the adsorption performance of CO2 and Hg in flue gas using corn straw and pine biochar modified by KOH

This study presents a comparative analysis of the adsorption performance of KOH-modified biochar derived from corn straw and pine for CO2 and Hg capture from coal-fired flue gas. The results indicate that the increase in KOH-activation temperature could significantly enhance the specific surface area. Pine biochar (PACs) activated at 800 °C exhibited the highest CO2 adsorption capacity, reaching 3.79 mmol/g at 25 °C. As well as, for corn straw biochar (CACs), the activation temperature of 700 °C is the optimal condition. The isosteric heat of adsorption for PACs and CACs is less than 40 kJ/mol and the R2 of the pseudo-first-order kinetic model exceeds 0.9, demonstrating that the CO2 adsorption of biochar mainly relies on physisorption. The main factor affecting the CO2 adsorption performance is the micropore capacity (<10 Å). CO2 capture positively correlates with carbon content and graphitization degree but negatively correlates with total pore volume and specific surface area. In addition, PACs and CACs present better CO2 adsorption performance after 10 cycles. PAC-800 can achieve CO2 desorption at lower temperatures and has higher selectivity for CO2, compared with CAC-700. CO2 can enhance the mercury removal efficiency of biochar to a certain extent. However, the maximum on-line mercury removal efficiency of both pine and corn straw biochar is less than 80 % under CO2 capture conditions, indicating that it is necessary to improve Hg capture performance by constructing higher-affinity sites on the surface of the biochar.

Adsorption Properties of Fishbone and Fishbone-Derived Biochar for Cadmium in Aqueous Solution

Cadmium (Cd) contamination in aquatic ecosystems is a serious global environmental issue. Biochar derived from agricultural wastes has recently attracted remarkable attention as it is used as an absorbent in combating heavy metal contamination of water bodies. In the present study, the absorption efficacy of fish bone (FBM) and fishbone-derived biochar prepared at 200 °C, 400 °C, 600 °C, and 800 °C (referred to as B200, B400, B600, and B800, respectively) for the Cd ion (Cd2+) in aqueous solution was investigated. The results showed that high-temperature pyrolysis could optimize the pore structure and specific surface area of FBM, and Cd2+ successfully adsorbed onto FBM and fishbone-derived biochar. High-temperature pyrolysis significantly increased the FBM adsorption capacity for Cd2+ by 49.5–135.1%, with the optimal pyrolysis temperature being 600 °C. Furthermore, the kinetic data of FBM and fishbone-derived biochar for Cd2+ were in better alignment with the pseudo-second-order model, their adsorption isotherms were better in accordance with the Langmuir models, and the thermodynamic analysis showed that the adsorption process was monolayer and favorable adsorption. Moreover, the potential adsorption mechanisms of Cd2+ on FBM and fishbone-derived biochar might be related to pore filling, ion exchange, complexation with oxygen functional groups, and precipitation with the minerals on the biochar surface. Fishbone-derived biochar has significant potential for wastewater treatment and agricultural waste applications.

Initial Desorption Characteristics of Gas in Tectonic Coal Under Vibration and Its Impact on Coal and Gas Outbursts

The rapid desorption of gas in coal is an important cause of gas over-limit and outbursts. In order to explain the causes of coal and gas outbursts induced by vibration, this paper studies the gas desorption experiments of tectonic coal with different particle sizes and different adsorption equilibrium pressures under 0~50 Hz vibration. High-pressure mercury intrusion experiments were used to measure the changes in pore volume and specific surface area of tectonic coal before and after vibration, revealing the control of pore structure changes on the initial desorption capacity of gas. Additionally, from the perspective of energy transformation during coal and gas outbursts, the effect of vibration on the process of coal and gas outbursts in tectonic coal was analyzed. The results showed that tectonic coal has strong initial desorption capacity, desorbing 29.58% to 54.51% of the ultimate desorption volume within 10 min. Vibration with frequencies of 0~50 Hz increased both the gas desorption ratios and desorption volume as the frequency increased. The initial desorption rate also increased with the vibration frequency, and vibration can enhance the initial desorption capacity of tectonic coal and delay the attenuation of desorption rate. Vibration affected the changes in the initial gas desorption rate and desorption rate attenuation coefficient by increasing the pore volume and specific surface area, with the changes in macropores and mesopores primarily affecting the initial desorption rate and 0~10 min desorption ratios, while the changes in micropores and minipores mainly influenced the attenuation rate of the desorption rate. Vibration increased the free gas expansion energy of tectonic coal as the frequency increased. During the incubation and triggering processes of coal and gas outbursts, vibration has been observed to accelerate the fragmentation and destabilisation of the coal body, while simultaneously increasing the gas expansion energy to a point where it reaches the threshold energy necessary for coal transportation, thus inducing and triggering the coal and gas protrusion. The study results elucidate, from an energy perspective, the underlying mechanisms that facilitate the occurrence of coal and gas outbursts, providing theoretical guidance for coal and gas outburst prevention and mine safety production.

Effects of solvent extraction on pore structure properties and oil distribution in shales of alkaline lacustrine basins

Shale contains numerous nano-scale pores, whose pore structure property changes affect petroleum flow, complicating shale oil accumulation and exploration. Twelve shale samples from the Permian Fengcheng Formation in the Mahu Sag and the Permian Lucaogou Formation in the Jimusar Sag in northwestern China were analyzed to investigate the coupled oil distribution and pore structure in shales from alkaline lacustrine basins. Shale samples were comprehensively analyzed before and after solvent extraction using X-ray diffraction, total organic carbon measurement, Rock-Eval analyses, field emission-scanning electron microscopy, nitrogen physisorption (NP), and (ultra) small-angle X-ray scattering [(U)SAXS] to assess nanoscale pore structure (2–300 nm in diameter) and oil distribution. Solvent extraction increased total pore volume and specific surface area (SSA). However, the accessibility of nanoscale pores remains limited. Additionally, even after retained oil removal, (U)SAXS-derived total pore volumes are 1–10.4 times larger than NP-derived connected pore volumes. Complex variations in pore volume and SSA mainly result from the removal of extractable organic matter (EOM) and the refilling of small pores by organic matter. Despite the relatively small pore volume of mesopores (2–50 nm), the amount of EOM distribution in mesopores is comparable to that in macropores (50–300 nm); therefore, it is crucial not to overlook the retention capacity of mesopores for EOM. Macropores, particularly interparticle pores associated with quartz and feldspar, play a crucial role in oil mobility. The quantity and composition of EOM, along with other factors, can alter pore structure before and after solvent extraction and should be considered in evaluating the distribution and content of free oil.

Synergistic enhancing low-rank coal flotation mechanisms using nanocarrier collector through pore sealing and surface hydrophobicity

Low-rank coal (LRC) is difficult to float using conventional oily collectors due to the rich oxygen-containing functional groups and abundant pores on its surface. In this study, an effective nanocarrier collector containing both nanoemulsion and nanoparticle with droplet size of 10–70 nm was developed, through diesel-beeswax mixture and AEO-7 using low-energy shearing and rapid cooling emulsification to enhance the LRC flotation. The surface morphology and elemental compositions of LRC were firstly characterized using SEM and EDS, identifying its difficult-to-float mechanisms. Then, the macroscopic appearance and microscopic size distribution of nanocarriers, and flotation tests were conducted to determine the optimum formula of nanocarrier collector for LRC. The results indicated that the recovery rate of combustibles was first increased and then decreased, by increasing the mass ratio of beeswax to diesel. When the mass ratio of diesel, beeswax, and AEO-7 was 2:3:5, the recovery rate of combustibles could be achieved to 92.98 %. Finally, the BET specific surface area, water adsorption, contact angle and wrap angle experiments were conducted to clarifying the synergistic enhancing LRC flotation mechanisms of nanocarriers collector. The nanocarriers could permeate into and seal the LRC surface pores, thereby reducing the both surface pore volumes and specific surface area. In addition, the mixtures of diesel and beeswax synergistically improved the surface hydrophobicity. Consequently, this research provides new insight into the development of effective collectors for LRC flotation.

Influence of CO2 injection on characterization of microscopic pore throat structure in shale reservoirs

CO2 injection to displace oil in shale reservoirs will form asphaltene precipitation and harm the microscopic pore-throat structure, influencing the displacement efficiency. However, asphaltene deposition harmed reservoir characteristics and the damage mechanism to microscopic pore-throat structure is not clear. In this study, on the basis of CO2 displacement experiments, nuclear magnetic resonance (NMR) scanning and low-temperature nitrogen adsorption (LTNA) experiments were used to investigate the damage characteristics of asphaltene deposition on physical properties, wettability, oil recovery and micro-structure of three types of reservoirs under different injection pressures, and reveal the microscopic damage mechanism of asphaltene precipitation on the pore-throat structure. The results show that after CO2 displacement, the permeability and porosity damage rate is positively correlated with injection pressure, the maximum damage rate is 45.84 % and 42.73 %, respectively. And the asphaltene precipitation results in wettability reversal of pore throats. In addition, the blockage rate of nano-scale pore throats in the three types of reservoirs is higher, with the highest blockage rates of 45.43 %, 52.41 % and 76.45 %, respectively. The worse the reservoir physical properties, the higher the pore throat blockage rate, and the greater damage to the micro-structure by asphaltene precipitation. The amplitude of the LTNA adsorption–desorption curves all decreased, and the adsorption amount of the core samples decreases. The contribution of micropore specific surface area of Type I and II reservoirs decreases, while the contribution of Type III reservoir increases up to 90.76 %. Asphaltene precipitation resulting in a decrease in total pore volume. Asphaltene particles are adsorbed on the pore surface, and the pore diameter decreases with the maximum decrease of 3.36%. The contribution of macropores to the total pore volume and specific surface area is significantly reduced compared to that of micropores and mesopores.

NiMOF-Derived MoSe2/NiSe Hollow Nanoflower Structures as Electrocatalysts for Hydrogen Evolution Reaction in Alkaline Medium.

Metal-organic frameworks (MOFs) are crystalline porous materials for storage and energy conversion applications with three-dimensional pore structure, high porosity, and specific surface area, which are widely utilized in electrocatalysis. Herein, MoSe2/NiSe composites were synthesized by selenization reaction using NiMOF as the precursor. The composites were hollow nanoflower structures with a synergistic effect between MoSe2 and NiSe to promote rapid electron transfer, which exhibited good hydrogen evolution reaction performance in an alkaline medium. At a current density of 10 mA/cm2, the HER overpotential reaches 80 mV, the Tafel slope is 33.86 mV/dec, and the material has good stability, with polarization curves remaining essentially unchanged after 3000 cycles. These results indicate that the method has a promising application in the preparation of efficient and sustainable catalysts for hydrogen production in alkaline medium.

Chemical Safety Assessment of Pitch-Based Activated Carbon Pellets via Highly Toxic Gas Adsorption Properties

This study focuses on the preparation of activated carbon using a petroleum-residue-based pitch, as well as the HCl gas adsorption properties of the resulting activated carbon pellets relative to their specific surface area and pore structure. Activated carbon was prepared under various oxidation and chemical activation conditions using pitch with a softening point of 220 °C. The activated carbon was mixed with distilled water, an acrylic binder, and carboxymethyl cellulose in a specific ratio to form pellets. These pellets were then dried in an oven at 80 °C. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller analyses were performed to evaluate the surface structure and specific surface area of the finalized pellets. HCl gas was adsorbed at a concentration of 50 ppm while examining the adsorption characteristics relative to the pore structure and specific surface area.

Enhancement of supercapacitor efficiency by Fe3+ doping in hydrothermally synthesized NiO nanoparticles

This study examines the physicochemical and electrochemical characteristics of hydrothermally produced, 800°C-annealed pure and Fe3+ doped (0.02, 0.04, and 0.06 M) NiO nanoparticles(NPs).The face-centred cubic structure of NiO NPs was verified by XRD analysis, and doping resulted in a decrease in crystallite size from 43.92 nm to 19.67 nm.FE-SEM revealed dense and irregularly arranged granular morphologies, while EDAX confirmed successful Fe3+ incorporation into NiO matrix. UV–Vis DRS showed an increase in bandgap energy from 3.15 eV to 3.71 eV. XPS confirmed the presence of Ni2+ and Fe3+ with their elemental compositions. According to BET analysis, Fe3+ doping increases pore size and specific surface area, which raises specific capacitance.VSM analysis of pure and Fe3+ doped NiO NPs demonstrated a transition from a weak ferromagnetic to a distinctive ferromagnetic behaviour, which is beneficial for energy storage as well as data storage applications.The electrochemical studies showed that 0.06 M Fe3+ doped NiO had the maximum specific capacitance of 360.96 F g−1 at the scan rate of 10 mV s−1and EIS Nyquist plots showed enhanced electrical conductivity. These results highlight the possibility of Fe3+ doped NiO NPs as excellent electrode materials for high-efficiency supercapacitors.