Pore Surface Roughness Research Articles

Fractal Characterization of Nanoscale Pores of Volcanic Reservoirs in the Dongling Area, Changling Fault Depression, Songliao Basin

Fractal theory is an efficient method to characterize quantitatively tight rocks. Volcanic rocks are very promising reservoirs, and their pore structures have considerable influence on the occurrence and percolation mechanisms of oil and gas. Therefore, the research topics of pore structure and fractal characteristics are important for sustainable volcanic resource development. The pore structure and fractal characteristics of microscopic pores of volcanic reservoirs in the Changling Fault Depression, Songliao Basin, were studied by combining fractal theory with mercury intrusion porosimetry and low-temperature nitrogen adsorption technique. After quantitative characterization of the nanoscale pore size distribution (PSD), four fractal dimensions were calculated. Subsequently, the relationships between fractal dimensions and pore structure parameters were evaluated. Three types of PSD models of volcanic reservoirs in the study area were established. The relationships between fractal dimensions and PSD models, as well as the clustering characteristics of the fractal dimensions, were investigated. The study revealed that the volcanic reservoirs developed a certain proportion of nanoscale pores with morphological characteristics dominated by wedge-shaped pores and slit pores. D4 is relatively strongly negatively correlated with pore size, illustrating that it can better reflect pore structure compared to the other fractal dimensions. Additionally, D4 can reflect pore surface roughness. This study shows that D1 and D2 can distinguish PSD models well, but D3 and D4 are more effective for the identification of the Type II PSD model. The fractal dimensions were divided into four clusters via hierarchical cluster analysis, each corresponding well to a certain PSD model or PSD model combination.

Fabrication of polymeric nanocomposite forward osmosis membranes for water desalination—A review

Osmosis has started discovering technical application in the developing membrane technologies like Forward Osmosis and Pressure-Retarded Osmosis. It is the natural motion of solvent through a semi-permeable membrane caused by a highly concentrated solute gradient. Such technologies use thin-film membranes supported by porous layers and scalable membrane materials which open the door to new generation membrane developments. Membrane fabrication has a strong connection with the membrane surface properties and performance such as pore structure, hydrophilicity, surface roughness and water flux. This article provides a perspective on the current efforts in membrane fabrication and application of nanocomposite membranes for water treatment. Thin-film nanocomposite membranes have been employed to tailor membrane with enhanced selectivity, permeability, internal concentration polarization, fouling and stability. The main focus of this review is on how membrane science and emerging nanomaterials have been applied for forward osmosis desalination and water purification to meet the increasing worldwide demands for water.

Influence of monomers involved in the fabrication of a novel PES based nanofiltration thin-film composite membrane and its performance in the treatment of common effluent (CETP) textile industrial wastewater

In this article, monomers (tannic acid (TA) and m- phenylenediamine (MPD)) were used in the fabrication of a novel PES based thin-film composite nanofiltration (TFC-NF) membrane for the treatment of a common effluent treatment plant (CETP) of textile industrial wastewater. PES support sheets and TFC layers were fabricated via non-solvent induced phase inversion and in-situ interfacial polymerization (IP) process. The ultra-thin active layer was synthesized via the IP process with monomers such as tannic acid (TA) and m- phenylenediamine (MPD). T and M series membranes correspond to (PES/x wt% TA, x = 2, 4, 6) as T1, T2, T3 -TA and (PES/x wt% MPD, x = 2, 4, 6) as M1, M2, M3-MPD respectively. M0 corresponds to PES which is the virgin membrane. The chemical structure, surface morphology, surface roughness and surface properties were explored using fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and contact angle, respectively. The filtration performance of the thin-film composite nanofiltration (TFC-NF) membranes was investigated by various properties like pure water flux, salt rejection, porosity, mean pore radius and antifouling analysis. T1-TA membrane showed better water permeability, high salt rejection and better industrial effluent rejection with 94.4% of TDS that are suitable for industrial reuse and agricultural irrigation. Moreover, for T1-TA membrane, the water flux, porosity, mean pore radius, salt rejection, surface roughness and contact angle of 43.5lm- 2 h - 1, 47.1%, 16.7nm, 72.7%, 11.7nm and 41.48°was achieved respectively that was found to be higher than that of all the other fabricated membranes. Further, the rejection efficiency rate of textile effluent characteristics such as pH, turbidity, TDS, alkalinity, total hardness, BOD and COD were also achieved with maximum deduction in the T1-TA TFC-NF membrane compared to the M0-Virgin PES membrane. From the results, it can be confirmed that the T1-TA membrane significantly reduced the alkalinity, total hardness, BOD and COD rejections of 78%, 77.3%, 58.5% and 67.5% respectively, present in the effluent. Water flux recovery ratio (FRR) was improved from 74.6% for M0-Virgin PES membrane to 94.8% for T1-TA membrane. The modified TFC-NF membranes especially T1-TA, had better anti-fouling property and excellent hydrophilicity than the unmodified M0-Virgin PES membrane. The online version contains supplementary material available at 10.1007/s40201-021-00624-x.

Effects of composition changes of coal treated with hydrochloric acid on pore structure and fractal characteristics

In order to investigate the influence of coal compositions on the pore structure, low temperature gas adsorption (LTGA) method was used to analyze the pore evolution of coal samples treated with hydrochloric acid. The results demonstrate that hydrochloric acid treatment significantly reduced the content of minerals and volatile matter in coal, which could increase the porosity and the pore connectivity of coal. The removal of volatile matter has an obvious reaming effect on supermicropores, but ultramicropores remained unchanged. The role of minerals in pores of different pore widths is different, which are the fillers in macropores, the skeletons of some large mesopores and the blockage in some small mesopores. With the decrease of minerals, the macropore volume increased, and the large mesopore volume first decreased and then increased. In addition, the opening of many closed small mesopores increased the fractal dimension D2 of pore structure complexity, and provides an increase in specific surface area, but it has no significant relationship with the fractal dimension D1 of pore surface roughness.

Synthesis and characterization of Mg0.4Ti0.6O2 alloy thin film

The present work includes the fabrication of Mg0.4Ti0.6O2 thin film (TF) based Metal-oxide–semiconductor (MOS) capacitor on (100) n-type GaAs substrates by electron beam evaporation technique. The thickness of the thin film alloy is found to be about 300 nm measured from Field emission gun-scanning electron microscope (FEG-SEM) data. The pore volume, surface roughness and grain size of the thin film samples are calculated from non-contact atomic force microscopy (NC-AFM) images. Experimental as well as analytical studies have been carried out to determine the bandgap and defect level transition of the material. The band-to-band transition of the Mg0.4Ti0.6O2 sample is calculated to be at ~ 5.2 eV. The as prepared sample shows tetragonal crystal structure. Presence of anatase phase of TiO2 in the TF material is confirmed through XRD (X-ray diffraction) investigation. Current (I) – Voltage (V) characteristics of the Mg0.4Ti0.6O2 Schottky devices reveal that the leakage current at −1 V is 8.1 × 10-4 A.

Nerve Response to Superelastic Shape Memory Polyurethane Aerogels.

We have previously shown the suitability of aerogels as scaffolds for neuronal cells. Here, we report on the use of superelastic shape memory polyurethane aerogels (SSMPA). SSMPA have a distinctly different stiffness than previously reported aerogels. The soft and deformable nature of SSMPA allowed for radial compression of the aerogel induced by a custom designed apparatus. This radial compression changed the pore diameter and surface roughness (Sa) of SSMPA, while maintaining similar stiffness. Two varieties of SSMPA were used, Mix-14 and Mix-18, with distinctly different pore diameters and Sa. Radial compression led to a decreased pore diameter, which, in turn, decreased the Sa. The use of custom designed apparatus and two types of SSMPA allowed us to examine the influence of stiffness, pore size, and Sa on the extension of processes (neurites) by PC12 neuronal cells. PC12 cells plated on SSMPA with a higher degree of radial compression extended fewer neurites per cell when compared to other groups. However, the average length of the neurites was significantly longer when compared to the unrestricted group and to those extended by cells plated on SSMPA with less radial compression. These results demonstrate that SSMPA with 1.9 µm pore diameter, 1.17 µm Sa, and 203 kPa stiffness provides the optimum combination of physical parameters for nerve regeneration.

Process synthesis and optimization of SiO2/PVDF mixed-matrix membrane for oil-water emulsion separation

In this study, and optimized silicon oxide (SiO2)/polyvinyledene fluoride (PVDF) mixed-matrix membrane formulation was developed using response surface methodology (RSM). SiO2 nanoparticles (NPs) concentration (1-3%), silane solution concentration (1:100-3:100 ratio of silane to ethanol) and duration of silanization process (240-600 s) were identified as the factor in affecting the membrane performance, both permeate flux and rejection. The synthesized membranes were characterized in terms of membrane pore size, porosity, surface roughness, and surface wettability. The optimum SiO2/PVDF mixed-matrix membrane formulation was obtained with 2.9% SiO2 NPs concentration, 2.22:100 ratio of silane to ethanol, with 496 seconds of salination process duration. The optimum SiO2/PVDF mixed-matrix membrane formulation exhibited an extraordinarily high oil droplets rejection (92.01%) with 27.57 L/m2 h of permeate flux at 1 bar of operating pressure.

Antifouling nanofiltration membrane via tetrathioterephthalate coating on aniline oligomers-grafted polyethersulfone for efficient dye and heavy metal ion removal

A novel antifouling tetrathioterephthalate coated-aniline oligomers functionalized polyethersulfone nanofiltration (T-AO functionalized PES NF) membrane was developed for dye rejection and heavy metal ion removal. First, the PES NF membrane was in situ functionalized by aniline oligomers grafting through aryl diazonium salt reduction reaction and then the resulting functionalized PES NF membrane was coated with tetrathioterephthalate and characterized in terms of surface hydrophilicity, surface morphology, overall porosity, active pore radius, pore radius distribution, surface roughness, zeta potential, and active layer thickness. FTIR and XPS analysis were also carried out to confirm the desired functional groups were successfully formed on the tetrathioterephthalate coated-aniline oligomers functionalized PES NF (T-AO functionalized PES NF) membrane. The pure water flux and the flux recovery ratio of the T-AO functionalized PES NF membrane increased about 500.30 and 175.06 %, respectively, in comparison to the PES membrane due to the presence of hydrophilic functional groups belong to the coating layer. The resultant membrane with high water flux provided impressive heavy metal ion and dye removal. Moreover, this type of PES membrane showed excellent antifouling behavior and long-term stability; this work introduces an antifouling membrane for potential application in heavy metal ion and dye removal.

Effect of pore morphology and surface roughness on wettability of porous titania films

Surface hydrophobicity/hydrophilicity of titania (TiO2) films, spin-coated on silicon wafers, were tuned by introducing surface mesopores with various morphologies using a triblock copolymer F38 as the template agent of different weight ratios via a sol-gel method. It is found that both the porosity (2.92 ∼ 33.03%) and the surface roughness (0.22 ∼ 0.43 nm for arithmetic mean roughness and 0.28 ∼ 0.58 nm for root mean square roughness) of the films increase monotonically as increasing F38 ratio from 5 to 25 wt%, accompanied by distinct changes of pore morphology from isolated mesopores with pore sizes of 5 ∼ 7 nm to longer worm-like pores (30 ∼ 100 nm in length). The apparent static contact angle (θ*) of the films with isolated mesopores is enhanced from ca. 90.6° to 100.1° as indicated by an increase of the roughness factor with incresing F38 from 5 to 15 wt%, which is in qualitative agreement with the Wenzel’s equation. Interestingly, the films with interconnected worm-like pores show obvious hydrophilicity (θ* = 80.7°) with further increasing F38 ratio higher than 20 wt%. The reversed surface wettability show that not only surface roughness but also pore morphology could significantly affect the wettability of the mesoporous TiO2 films.

FRACTAL ANALYSIS OF SURFACE ROUGHNESS EFFECTS ON GAS DIFFUSION IN POROUS NANOFIBERS

Fractal model of gas diffusion in porous nanofibers with rough surfaces is derived, in which the porous structure is assumed to be composed of a bundle of tortuous capillaries whose pore size distribution and surface roughness follow the fractal scaling laws. The analytical expression for gas relative diffusion coefficient is a function of the relative roughness and the other microstructural parameters (porosity, the fractal dimension for pore size distribution and tortuosity, the maximum and minimum pore diameter and the characteristic length). The proposed fractal model is validated by comparison with available experimental data and correlations. At the same time, the effect of microstructural parameters of porous fibrous materials on gas diffusion has been studied in detail. It is believed that the current model may be extended to porous materials other than fibrous materials.

Understanding electrokinetic thermodynamics in nanochannels

• Both the analytical and numerical conversion efficiency are obtained. • A maximum efficiency is found when the pore radius is around the Debye length. • Small roughness can improve the conversion efficiency. Understanding the electrokinetic conversion efficiency in a nanochannel is vital for designing energy storage and conversion devices. In this paper, an analytical electrokinetic energy conversion efficiency in a nanochannel is obtained based on the linear electrokinetic response. The analytical result shows that the conversion efficiency has a maximum with the increasing of the nanochannel pore radius. Numerical solutions based on the Poisson-Nernst-Planck (PNP) and Navier-Stokes (NS) equations are used to confirm the analytical expressions. Besides, the influences of the pore radius and surface roughness on the conversion efficiency in nanochannels are also studied by the numerical calculations. In particular, the influences of the surface roughness on the fluid flow, streaming current and streaming potential are examined. The results show that the large bumps and grooves representing the roughness can hinder the fluid flows and ion transports in the nanochannels. The maximum efficiency in a smooth nanochannel is higher than that in a rough channel. However, the small bumps and grooves can increase the surface area of the channel, which is beneficial to improving the conversion efficiency in some cases. This research can provide theoretical guidance to design electrokinetic energy conversion devices.

A Local-Effective-Viscosity Multirelaxation-Time Lattice Boltzmann Pore-Network Coupling Model for Gas Transport in Complex Nanoporous Media

Summary Gas transport in nanoporous media is controlled by both the nanoscale mechanisms and complex pore structure, details of which can accurately capture the detailed gas-transport behavior. However, direct-simulation methods in large digitized samples are not feasible because of high memory and computational-time demands. Furthermore, our previous work (Landry et al. 2016) shows that when resolution of the digitized sample is not ample, the sample has to be further magnified up to five times along each linear dimension to achieve the desired accuracy. Here we propose a local-effective-viscosity multirelaxation-time lattice Boltzmann pore-network coupling model (LEV-LBM-PNM) to tackle these problems. We ran a large number of LEV-LBM simulations in high-resolution geometries with simple cross sections that had surface roughness added to them in a controlled manner. Such carefully selected geometries were run at a large number of pressure conditions to establish gas-flux correlations that depend on shape, Knudsen number, and surface roughness and can be directly used in PNM to account for all of those properties. The semianalytical gas-transport models for a single pore with various cross-sectional shapes and surface roughness were established using the LEV-LBM simulation results. The established semianalytical gas-transport model is then implemented into a 3D pore-network model to investigate the gas-transport behavior at various conditions. In an example application, the pore-network model was extracted from a Marcellus Shale focused-ion-beam scanning-electron-microscopy (FIB-SEM) image using the maximum inscribed sphere method. We found that the proposed LEV-LBM-PNM accurately predicts gas apparent permeability by accounting for gas slip in irregular pore shape and surface roughness.

Link Between CO2‐Induced Wettability and Pore Architecture Alteration

AbstractChanges in pore (throat) size, surface roughness, and mineralogy induced by supercritical CO2‐water‐rock reactions impact petrophysical properties such as porosity, permeability, and especially wettability. Herein, we show that these changes directly impact relative permeability and capillary pressure curves, a fact rarely studied in the literature. In this work, we show that CO2 contact angle changes emerge after Madison Limestone samples were soaked for 400 hr in CO2‐enriched brine. Coreflooding results show that the water production rate and cumulative water production increased after the rock was exposed to carbonic acid. Moreover, the mercury capillary pressure decreased in mesopores and macropores, indicating the increase of size in these pores due to reactions. This compounded wettability and pore network alteration can directly affect CO2 injectivity, migration, and storage capacity. This fundamental insight into CO2 geological storage processes should aid practitioners to reduce uncertainties in forecasting CO2 distribution via injection simulation.

Recycling waste plastics as hollow fiber substrates to improve the anti-wettability of supported ionic liquid membranes for CO2 separation

In this study, hydrophobic waste poly(styrene-co-butadiene)-derived polymeric hollow fiber fabricated via a dry-jet wet spinning method were used as substrates to support ionic liquid (IL) membranes via the dip-coating method. The surface properties of the substrates, such as pore size and its distribution, roughness, and wettability, were adjusted by changing the air gap distance during the spinning process. The roughness of the outer surface of the substrates decreased from 5.57 nm to 3.81 nm as the air gap increased from 0 cm to 20 cm. As a smoother surface was obtained, the wetting stability of the substrate was enhanced, thereby promoting thin supported ionic liquid membranes (SILMs) formation. The SILMs obtained were used to separate CO2 gas from N2, and the separation performance of single and binary gases and long-term stability of SILMs were evaluated. Results indicated that the use of sponge-like hollow fibers as a substrate yields a CO2 permeability of over 745.74 barrer and CO2/N2 selectivity of 17.8. Furthermore, when the transmembrane pressure was enhanced to 2.25 bar, the SILMs exhibited good membrane stability, an enhanced CO2 permeability of 1018.54 barrer, and a CO2/N2 selectivity of 20.17. This study revealed that the wetting behavior of IL is affected by the pore structure and surface roughness of the hollow fibers. Therefore, the surface property of substrates is a key point in improving the completeness and stability of SILMs in the gas separation process.

Apparent Liquid Permeability in Mixed-Wet Shale Permeable Media

Apparent liquid permeability (ALP) in ultra-confined permeable media is primarily governed by the pore confinement and fluid–rock interactions. A new ALP model is required to predict the interactive effect of the above two on the flow in mixed-wet, heterogeneous nanoporous media. This study derives an ALP model and integrates the compiled results from molecular dynamics (MD) simulations, scanning electron microscopy, atomic force microscopy, and mercury injection capillary pressure. The ALP model assumes viscous forces, capillary forces, and liquid slippage in tortuous, rough pore throats. Predictions of the slippage of water and octane are validated against MD data reported in the literature. In up-scaling the proposed liquid transport model to the representative-elementary-volume scale, we integrate the geological fractals of the shale rock samples including their pore size distribution, pore throat tortuosity, and pore-surface roughness. Sensitivity results for the ALP indicate that when the pore size is below 100 nm pore confinement allows oil to slip in both hydrophobic and hydrophilic pores, yet it also restricts the ALP due to the restricted intrinsic permeability. The ALP reduces to the well-established Carman–Kozeny equation for no-slip viscous flow in a bundle of capillaries, which reveals a distinguishable liquid flow behavior in shales versus conventional rocks. Compared to the Klinkenberg equation, the proposed ALP model reveals an important insight into the similarities and differences between liquid versus gas flow in shales.

Fractal characterization of pore structure and its influence on salt ion diffusion behavior in marine shale reservoirs

Hydraulic fracturing becomes a significant way to develop fossil hydrogen energy from marine shale. Some marine shale formations have a higher salt ion concentration in flowback fluid, about which the mechanism is still unclear. In this study, both the fractal characterization of pore structure and its influence on salt ion diffusion was researched. The fractal dimension D1 can reflect the roughness of pore surface, and the fractal dimension D2 can reflect the complexity of pore structure. The fractal dimension D1 of Sichuan Niutitang Formation is only 2.0069 and the ones of other shale samples are between 2.5291 and 2.6341, which means that the pore surface of Sichuan Niutitang Formation is far smoother than the ones of other samples. The fractal dimension D2 ranges from 2.7396 to 2.9546, which indicates that all samples have complex pore structure. The salt ion diffusion rate is mainly controlled by specific surface area, median pore-throat radius and clay content. A higher specific surface area provides more surface for the interaction between liquid and matrix, and lots of salt ion was released into imbibed liquid. A larger median pore-throat radius benefits to salt ion diffusing out of sample, thus a higher salt ion diffusion rate appears. The liquid can cause the clay-swelling which has the potential to reduce the salt ion diffusion channel, thus the higher the clay content, the lower the salt ion diffusion rate. Our research is conducive to understanding the fractal characterization of marine shale and its impact on high salt ion concentration in flowback fluid.

PVDF mixed matrix ultrafiltration membrane incorporated with deformed rebar-like Fe3O4–palygorskite nanocomposites to enhance strength and antifouling properties

A novel PVDF mixed matrix ultrafiltration membrane was prepared by blending PVDF with the deformed rebar-like Fe3O4–palygorskite nanocomposites (MPGS) using the chemical coprecipitation method. Fe3O4 nanoparticles were anchored on the surface of the palygorskite nanofibers to form deformed rebar-like structures. MPGS were then distributed uniformly on the membrane matrix. PVDF chains firmly wrapped by the deformed rebar-like nanocomposites consequently enhanced the tensile strength of the PVDF membrane. At 7.0 wt % MPGS, the tensile strength increased from 1.59 MPa to 2.66 MPa. The overall thickness, skin layer thickness, finger-like voids, average pore size and surface roughness of membranes decreased with increasing amounts of MPGS. The rejection of the membrane increased to 99.09% at 7.0 wt % MPGS. The contact angle of membranes decreased from 99.14° (pure PVDF) to 78.76° (PVDF/7.0 wt % MPGS). On the other hand, the pure water flux of membranes increased from 123.57 L m−2 h−1 (pure PVDF) to 356.16 L m−2 h−1 (PVDF/7.0 wt % MPGS). The flux recovery rate of the mixed matrix membranes (PVDF/7.0 wt % MPGS) was as high as 80%. This was more than twice that of the pure PVDF membrane (31.6%). These results demonstrated that the deformed rebar-like structure of the MPGS played a critical role in determining the structures and properties of PVDF mixed matrix ultrafiltration membranes. The hydrophilicity, thermal stability, permeation flux and antifouling property of the mixed matrix membranes increased with addition of MPGS. As such, PVDF/MPGS membranes had excellent comprehensive properties thus making them ideal for application in numerous fields.

Characteristics of pore structure of stabilized/solidified sediments during freeze–thaw cycles

The stabilized/solidified (S/S) sediments are supposed to be damaged by freeze–thaw cycles (FTs), and their deformation parameters such as void ratio, compression modulus and consolidation coefficient changed during FTs. The characteristics of pore structure of S/S sediments during FTs are critical for identifying the damage mechanisms, since these damages are primarily induced by the water-phase changes in the pores. Hence, FTs were first simulated in laboratory to prepare S/S sediments samples in different conditions. Then, oedometer tests were launched on these samples to observe the changing of the deformation parameters of S/S sediments in different FTs. After that, scanning electron microscopy analysis (SEM) was applied to observe the changing of the micro pore structure aspects of S/S sediments in different FTs. And finally, the combined application of mercury intrusion porosimetry analysis (MIP) and nitrogen adsorption porosimetry analysis (NAP) was conducted to ascertain the changing of the micro pore structure of S/S sediments in different FTs quantitatively, including the changing of pore-size distributions and pore surface roughness. The comprehensive analysis of pore structure of S/S sediments by SEM, MIP and NAP appropriately explained the changes of deformation parameters in the oedometer tests. Furthermore, the necessity and validity of combined application of MIP and NAP were proved, for full-scale pore structure analysis of S/S sediments during FTs.

Effect of nano-SiO2/styrene-acrylic emulsion on compactness and strength of mine drilling seal materials

Superior performance drilling seal materials can significantly enhance coal mine gas extraction efficiency. In order to enhance the material properties, nano-SiO2, sodium silicate and styrene-acrylic emulsion are selected to optimize the pore structure and strength of the material. The results show that pores in the unmodified cement-based sealing material are mostly mesoporous, accounting for 95.44%, microporous is 4.56%. Synergistic effect of sodium silicate and SiO2 increased the proportion of microporous to 10.62%, but the total porosity is higher than that of ordinary sealing materials. SiO2 and styrene-acrylic emulsion greatly reduce the pore volume of the material. The pore volume decreases from 0.09418 cc/g to 0.05621 cc/g, and the microporous increases to 16.67%. The fractal dimensions D1 and D2 decreased by 2.73% and 3.84%, indicating that the pore surface roughness increased and the pore structure became more complicated. This paper is of great significance for improving the efficiency of gas mining.

Pore structure and diffusion characteristics of intact and tectonic coals: Implications for selection of CO2 geological sequestration site

With the increasing amount of CO2 in the atmosphere, geologic sequestration becomes a promising measure to reduce the rising concentration of CO2. During the process of CO2 injection into coal seam to store CO2, it is critical to select the appropriate coal seam. In order to study whether the intact or tectonic coal is more suitable for CO2 geological sequestration, the pore structure characteristics and fractal dimensions of these coal samples were analyzed by mercury intrusion porosimetry, N2 (77 K)/CO2 (273 K) adsorption methods, and methane adsorption and diffusion properties of these coal samples were obtained. The results show that tectonic coals have greater pore volume and specific surface area of micropore, mesopore and macropore, while the fractal dimensions of the tectonic coals are smaller (that is, simpler pore structure, smaller pore surface roughness) than that of the intact coals, indicating that tectonic coal has more favorable pore structure to provide more adsorption sites for CO2 storage. Furthermore, better connectivity as well as the adsorption and diffusion capacity of tectonic coals have been significantly improved compared to intact coals, which indicates that CO2 is easier to migrate into the internal pore system of tectonic coal in a short time, reducing the time consumed by CO2 injection into the coal seam, thus saving the cost of CO2 storage. Interestingly, a fractal conceptual model is proposed to account for the evolution of original long and complex pores were converted into short and simple pores, and closed pores transformed into connectivity pores during the formation of tectonic coals. Therefore, the results of this study contribute to understand the advantages of tectonic coal reservoirs as target sites for CO2 geological sequestration.