Average Specific Surface Area Research Articles

Heterogeneity Characteristics of Lacustrine Shale Oil Reservoir Under the Control of Lithofacies: A Case Study of the Dongyuemiao Member of Jurassic Ziliujing Formation, Sichuan Basin

The lacustrine shale in the Dongyuemiao Member of the Fuling area, Sichuan Basin, is widely distributed and has huge shale oil resource potential. It is one of the important replacement areas for shale oil exploration in China. To investigate the key shale oil evaluation well, Well FY10, in the Fuling area, X-ray diffraction (XRD) mineral analysis, Rock-Eval, argon ion polishing-scanning electron microscope (SEM), Mercury injection capillary pressure (MICP), and low pressure nitrogen adsorption were launched to determine the heterogeneity of the pore system in the lacustrine shale of the Dongyuemiao Member. The mineral composition exhibits a high degree of heterogeneity, and the shale can be divided into two main lithofacies: argillaceous shale and mixed shale. The porosity ranges from 2.95 to 8.43%, and the permeability ranges from 0.05 to 1.07 × 10−3 μm2. The physical properties of mixed shale are obviously better than those of argillaceous shale. Inorganic mineral pores, such as linear pores between clay minerals and calcite dissolution pores, are mainly developed, while a small amount of organic pores can be observed. The average total pore volume (Vp) is 0.038 ml/g with an average specific surface area of 5.38 m2/g. Mesopores provide the main Vp (average 61.72%), and micropores provide mostly specific surface area. TOC imposes a strong controlling effect on the development of micropores. Clay minerals are the main contributors to mesopores and macropores. The organic-inorganic interaction during the process of diagenesis and hydrocarbon generation controls the formation of shale pore systems.

A novel preparation of high purity TiO2 from industrial low concentration TiOSO4 solution via short sulfate process

High purity TiO2 was prepared by authigenic seed thermal hydrolysis route from industrial low concentration titanyl sulfate solution via the short sulfate process. The hydrolysis conditions had important influences on the hydrolysis process. The appropriate induced water volume ratio and hydrolysis time were conducive to form appropriate quantity and quality of hydrolysis seeds, adjust and control the precipitation, crystal growth, particle growth and aggregation velocity for the hydrated TiO2, which could obtain the hydrated TiO2 with smaller average particle size and specific surface area. These effects were beneficial to reduce the adsorption of impurities, and improve the purity of TiO2. The hydrolysis conditions had internal influencing relationship between them. The optimized hydrolysis conditions were the induced water volume ratio was of 60%, the hydrolysis time was of 120 min, and the high purity, monodisperse titanium dioxide over 99.98% content could be obtained.

NiO/CeO2-Sm2O3 nanocomposites for partial oxidation of methane: In-situ experiments by dispersive X-ray absorption spectroscopy

In this work, we analyze Sm2O3-doped CeO2 (SDC) nanopowders and NiO/SDC nanocomposites in terms of sample reducibility and catalytic activity for partial oxidation of methane. We assess the role of the average crystallite size and specific surface area in Ni and Ce reduction kinetics by in-situ X-ray absorption spectroscopy experiments in diluted H2 and CH4/O2 mixtures. Our results indicate that crystallite size and surface area play a key role in CH4 activation through modification of the sample redox behavior. The oxidation of the metallic phase is the main cause of sample deactivation. A clear relationship is established between the temperature of maximum Ni oxidation rate and grain size. An interplay between Ce atoms from the support and Ni from the active phase was observed during the experiments, evidencing a complex relationship between oxygen vacancy concentration and catalytic activity. A high Ce3+ content in catalyst support was detrimental to catalytic activity

Process optimization of plasma-catalytic formaldehyde removal using MnOx–Fe2O3 catalysts by response surface methodology

To remove the toxic formaldehyde efficiently, a non-thermal plasma (NTP) system incorporated with MnOx–Fe2O3 catalyst has been developed herein. A response surface methodology (RSM) was utilized to explore the effects of a variety of experimental parameters (gas flow rate, molar ratio of Fe/Mn, and discharge power) on formaldehyde degradation systematically. The results demonstrated that the discharge power has the greatest impact on the formaldehyde degradation process, while the molar ratio of Fe/Mn has the least influence. Moreover, the amount of adsorbed oxygen species, reducibility, and average specific surface area of the tested catalyst are estimated as the dominant factors influencing the catalytic performance. Importantly, the optimal formaldehyde removal efficiency (95.01%) and CO2 selectivity (86.20%) were acquired at 5 W discharge power, 0.5 L min−1 gas flow rate, and 0.71 Fe/Mn molar ratio. This study can thus provide an efficient strategy for formaldehyde removal.

A facile synthesis of high-crystalline g-C3N4 nanosheets with closed self-assembly strategy for enhanced photocatalytic H2 evolution

High crystallinity and few layers of carbon nitride (g-C3N4) can increase carrier migration rate and photocatalytic activity sites, which is beneficial to enhance the photocatalytic activity of carbon nitride. Herein, we synthesized high-crystalline g-C3N4 nanosheets with a facile method of closed self-assembly strategy without adding any template and other auxiliary materials. XRD and HRTEM exhibited that high-crystalline g-C3N4 was synthesized, the average thickness and specific surface area of the high-crystalline g-C3N4 nanosheets were 4.8 nm and 95.10 m2g−1, respectively. Due to the efficient separation of photogenerated carriers and low charge-transfer resistance, high-crystalline g-C3N4 nanosheets demonstrated much better photocatalytic activity (8116 μmol h−1 g−1) than that of bulk g-C3N4, exhibiting 6-folds of enhancement on hydrogen evolution. Beneficial from its good photocatalytic activity and convenient fabrication method, it is anticipated that high-crystalline g-C3N4 nanosheets will find more applications in the renewable energy fields.

Preparation and characterization of manganese oxides supported on functionalized halloysite nanotubes with enhanced catalytic oxidation for toluene

In this study, halloysite (Hal) nanotubes treated with an acid and intercalation, were designed as a functionalized nanotubular structure to load and improve the dispersion of the Mn oxide doping of CeO for the toluene oxidation. The prepared catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The average pore size and specific surface areas of Hal nanotubes treated with an acid and intercalation (AI-Hal) offered significant improvement. The XRD and TEM indicated that different types of MnO2 were successfully loaded on the external surface of AI-Hal nanotubes. The XPS data confirmed that the MnIII and MnIV dominated on the surface of MnO2 due to the reversible redox reaction between MnIII and MnIV. The evaluation of catalytic activities showed that the γ-MnO2/AI-Hal presented good TOC performance of toluene. The doped CeO particles with diameters of approximately 10 nm were adsorbed on the external surfaces and lumen of Hal nanotubes and displayed a homogeneous dispersion state, which significantly improved the catalytic performance of the γ-MnO2/AI-Hal catalyst system with the T90 of 265 °C. The study indicated that catalytic activity of AI-Hal nanotube-supported manganese oxides was dependent on the valence state, oxygen vacancy and dispersion of active sites, and Hal nanotubes are acceptable reactants for the synthesis of supported catalysts with suitable MnOx.

Characterisation of calcium aluminate cement hydration: comparison of low-field NMR and conventional methods

The early hydration process of calcium aluminate cement (CAC) was characterised by low-field nuclear magnetic resonance (LF-NMR), isothermal calorimetry (IC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was revealed that LF-NMR characterisation of the hydration process gives results very similar to those of IC; both show that the hydration reaction is faster in about 10–17 h. In addition, the hydration process of CAC could be quantitatively divided into four stages according to the second derivative of LF-NMR signal amplitude. LF-NMR is also used in the study of CAC microstructure. The results of the T2 distribution curve prove that there are mainly two kinds of pores of different sizes in the slurry, and they gradually become smaller, especially in more than 10 h. The weighted average T2 and specific surface area decreased and increased, respectively, due to the gradual densification of the slurry. Owing to the conversion of CAH10 and C2AH8 to C3AH6, the solid specific surface area decreased, resulting in the LF-NMR specific surface area curve slowing down or even decreasing in about 20–50 h of hydration. XRD and SEM results further validate the characterisation of hydrated CAC microstructure by LF-NMR.

Synthesis and Characterization of Adsorbent Biochar/MnFe2O4 Composite from Agricultural Residue for Wastewater Treatment

Agriculture residue is produced every year in millions of tons worldwide and can be used as cheaper and environmentally friendly adsorbent. Herein, the biochar was synthesized by pyrolysis from coconut hull, corncob, rice husk, peanut hull and wheat straw. Total organic carbon was determined by standard TC-IC method, i.e., for Wheat Straw was found 20% highest among others agricultural residue and selected for biochar/MnFe2O4 composite synthesis. FTIR spectroscopy showed a band at 630 cm−1 that confirms the presence of MnFe2O4. BET surface analysis data showed the average specific surface area of biochar in the range of (4.3–79.389 m2 g−1). The surface area of biochar/MnFe2O4 composite was 149.96 m2 g−1, which was highest of all synthesized biochar’s. Adsorption study was carried out by using a specified amount of biochar for the specified time in a 50 ml wastewater sample of known chemical oxygen demand (COD) value. Biochar/MnFe2O4 adsorbent composite showed greater COD reducing the capacity of 70% than that of biochar produced without the formation of precipitates of MnFe2O4. The combination of various appealing attributes including cost-effective, environmentally friendly, and good COD reducing ability makes adsorbent a good option to be used in industrial applications specifically in the field of water treatment.

On the modelling of the peripheral fragmentation during coal char gasification with CO2

In this paper, a novel mathematical model for the coal char gasification with CO2 is developed. This new approach considers the non-uniformity of pore size distribution, the longitudinal growth of pores due to the surface reaction between CO2 and char, the pore overlapping effect, and the peripheral fragmentation phenomenon. This phenomenon was simulated by incorporating a fragmentation criterion based on both a critical porosity and a critical porosity gradient. Model predictions were compared with experimental data taken by sieving, gas adsorption porosimetry and surface area analysis, and a remarkable agreement was obtained. It was found that critical porosity and critical porosity gradient do not depend either on the operating conditions or the initial particle size but on the initial microstructure of the coal char. Furthermore, these two parameters could not vary significantly between different coal char samples. Regarding the fragmentation, it is observed that as the diffusional limitation increases, this phenomenon takes place in even earlier stages of reaction due to the appearance of porosity gradients within the particle. It was also observed that a maximum on the specific surface area appears due to the pore overlapping phenomenon, and that under chemical control conditions, the average specific surface area that can be reached is larger than that obtained under conditions with diffusional limitations.

Characterization of fibers after xylanase and modified laccase-glutamate system biobleaching of old newsprint pulp

Abstract The macroscopic and microscopic properties of old newsprint pulp with xylanase, MLac/Glu (modified laccase-glutamate system), and X-MLac/Glu (xylanase synergistic modified laccase-glutamate system) pretreatment was investigated by means of fiber quality measurements (FQA), attenuated total reflectance-infrared spectroscopy (ATR-IR), headspace gas chromatography (HSGC), X-ray diffract ion method (XRD), Low-temperature nitrogen absorption and scanning electron microscopy (SEM). Results showed that, compare with the control pulp, the brightness and lightness ( L ∗ {L^{\ast }} ) of hydrogen peroxide bleached pulp after X-MLac/Glu pretreatment increased by 5.86 % ISO and 3.58 %, respectively. FQA analysis revealed that coarseness and fine fiber content increased slightly. The content of carboxyl groups and water retention value increased remarkably by 31.11 % and 39.22 %, respectively. The paper physical analysis showed that the paper strength properties have improved significantly. The crystallinity of cellulose decreased by 3.82 % due to X-MLac/Glu pretreatment. ATR-IR analysis indicated some non-cellulose components are removed. The BJH average pore size and BET specific surface area increased after enzyme pretreatment. The SEM analysis showed that through X-MLac/Glu treatment the fiber surface becomes rough and the connections between the fibers become tighter, more fibrils appeared.

Impact of the heat treatment conditions on crystal structure, morphology and magnetic properties evolution in BaM nanohexaferrites

Present paper reports about the strong correlation of the heat treatment conditions (annealing), crystal structure parameters, microstructure and magnetic properties evolution in nanosized BaFe12O19 M-type hexaferrites or BaM nanohexaferrites. Samples of the BaM nanohexaferrites were obtained using sol-gel method with further annealing in the range 600–1100 °C. All investigated samples were single phase and described by the P63/mmc space group. Unusual and non-linear behavior of the lattice parameters with annealing temperature increasing from 600 to 1100 °C was explained by the competition of the increase in the average crystallite size (decrease in the surface tension effect) and increase in the level of their chemical homogeneity (anionic stoichiometry). Increase of the heat treatment temperature leads to increase of the microstructure parameters (average crystal size and specific surface area) and non-linear changes in magnetic properties. Correlation of the annealing temperature and magnetic properties was discussed in terms of the structural features.

Catalytic performance of Samarium-modified Ni catalysts over Al2O3–CaO support for dry reforming of methane

Mesoporous calcina-modified alumina (Al2O3–CaO) support was produced through the simple and economical co-precipitation method, then nickel (Ni, 10 wt%) and samarium (Sm, 3 wt%) ions loaded by two-solvent impregnation and one-pot strategies. The unpromoted/samarium-promoted catalysts were evaluated using X-ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HR-TEM), nitrogen adsorption-desorption, Temperature Programmed Oxidation/Reduction (TPR/TPO), and Field Emission Electron Scanning Microscopy (FE-SEM) methods, then investigated in methane dry reforming. The results revealed that with adding samarium to Ni catalyst through impregnation method, the average Ni crystallite size and specific surface area decreased from 11.5 to 5.75 nm and from 76.08 to 30.9 m2/g, respectively; as a result, the catalytic activity increased from about 50% to 68% at 700 °C. Furthermore, the TPO and FE-SEM tests indicated the formation of carbon with nanotube nature on the catalyst surface.

Mineralogical and pore structure of organic-rich deltaic shales and sub-bituminous coals from early Maastrichtian Mamu Formation, Anambra Basin, Nigeria

The Mamu Formation source rocks in the Anambra Basin are targets for shale gas reservoir. However, fundamental data on the critical pore structures for assessing the shale reservoir capabilities are lacking. In this study, the source rocks were investigated for their mineralogical compositions and pore structure characteristics by X-ray diffraction, accelerated surface area and porosimetry and field emission scanning electron microscopy (FE-SEM). The bulk mineralogy of the samples is dominated by kaolinite and quartz with average percentage composition of 52.0 and 41.5, respectively, suggesting that the rocks are potential candidates for fracking. The total average pore volume and specific surface area in the samples are 0.0421 cm3/g and 22.43 m2/g, respectively. The shale samples show higher amounts of total pore volumes relative to the sub-bituminous coals. No obvious organic pore is observed in the shale samples, but some inherited primary organic matter pores of plant origin exist in the sub-bituminous coals. Therefore, inorganic minerals pores are the major contributors to the pore development in the immature shales. The FE-SEM results reveal that the pore network in the shales is dominated by intraparticle pores and fractures. The observed well-developed fractures within the Mamu shales that may have resulted from tectonic events are capable of positively influencing the petrophysical properties of shales in the basin and by extension assist in shale gas exploration and development in the entire Lower Benue Trough.

Pore characterization of Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation shale gas reservoirs, Sichuan Basin, China

In order to investigate pore structure characteristics of Wufeng and Longmaxi Formations shales in the Sichuan Basin, the organic geochemical parameter and petrologic experiments, N2 and CO2 adsorptions, field emission scanning electron microscopy analysis and helium porosity measurement are carried out. Results showed that the thermal maturity of shales belong to over-maturity stage with TOC content and porosity of 1.84%–6.82% and 2.6%–5.1%, respectively. The TOC content has a good correlation with quartz, weak correlation with clay and no correlation with carbonate, indicating that the organic matter is mainly controlled by quartz content. The N2 and CO2 specific surface areas of organic-rich shale is generally 16.86–29.71 m2/g and 13.76–26.47 m2/g, respectively and the average N2 and CO2 specific surface area of organic-poor shale are 8.91 m2/g and 9.11 m2/g respectively, which indicating that the organic-rich shale has higher specific surface area, pore volume and smaller average pore diameter than that of organic-poor shale. The specific surface area in organic-rich shale is mainly contributed by micropores, while the pore volume is mainly contributed by mesopores, followed by micropores. There is a very strong correlation between TOC and CO2 and N2 specific surface area, indicating that pores were controlled by organic matter. Both porosity and specific surface have a positive relation when clay content is less than 28% for organic-rich shale, and its correlation is not obvious when clay content is more than 28% for organic-poor shale, indicating that the clay has a certain effect on reservoir.

Dechlorination of 2,4‐dichlorophenoxyacetic acid using biochar‐supported nano‐palladium/iron: Preparation, characterization, and influencing factors

In the present study, peanut shell, a green waste raw material, was used to prepare biochar (BC) and to obtain BC‐supported nano‐palladium/iron (BC‐nPd/Fe) composites for removing 2,4‐dichlorophenoxyacetic acid (2,4‐D) from water. Characterization analysis demonstrated that nPd/Fe particles were well dispersed on the BC surface with weakened magnetic properties. The average particle diameter and specific surface area of nPd/Fe were 101.3 nm and 6.7 m2 g−1, whereas the corresponding values of the BC‐nPd/Fe materials were 88.8 nm and 14.8 m2 g−1, respectively. Several factors were found to influence the dechlorination of 2,4‐D, including the weight ratio of BC to Fe, Pd loading ratio, initial solution pH, 2,4‐D concentration, and reaction temperature. Dechlorination results indicated that the 2,4‐D removal and phenoxyacetic acid (PA) generation rates were 44.1% and 20.1%, respectively, in the nPd/Fe system, and 100.0% and 92.1%, respectively, in the BC‐nPd/Fe system. The dechlorination of 2,4‐D was well described by the pseudo‐first‐order kinetic model (R2 > 0.97), and the observed rate constants kobs were 0.0042 min (nPd/Fe) and 0.0578 min (BC‐nPd/Fe), respectively. The reaction mechanism indicated that the dechlorination hydrogenation was the main process to remove 2,4‐D from water in the BC‐nPd/Fe system. In addition, BC inhibited the formation of a passivation layer on the particle surface during the reaction, thus maintaining the high reactivity of BC‐nPd/Fe. The easy preparation technique, high 2,4‐D dechlorination capacity, and mild reaction conditions suggest that BC‐nPd/Fe may be a promising alternative composite to remove 2,4‐D from water.

The characteristics and developmental control factors of microscopic pore structure in shale gas reservoirs in the Lower Cambrian Qiongzhusi Formation

The Early Cambrian Qiongzhusi Formation on the southern margin of the Sichuan Basin (Southern China) has experienced a long geological process. High degree of thermal evolution of the organic matter shows a great impact on the organic evolution, reservoir microscopic pore types and structure characteristics in this formation. In this study, we investigate the major types and structural features of microscopic pores in shale gas reservoirs of the Qiongzhusi FM. Different types of matrix pores are found, over-mature shale gas reservoirs in the Qiongzhusi FM. mainly have well-developed micropores, but their average specific surface area (SSA) and pore volume are smaller than those in the Longmaxi Formation. The degree of thermal evolution poses the greatest impact on microscopic pore structure, which is significantly positively correlated with SSA and pore volume; however, when exceeding this range, SSA and pore volume both drastically decrease with increasing degree of thermal evolution. Compared with those in the Longmaxi FM., microscopic pores of shale gas reservoirs in the Qiongzhusi FM. feature pore- SSA and large surface porosity. The better the development of micropores, the larger the SSA and Vp of shales, which are more conducive to shale gas adsorption and accumulation.

Reconstructing the 3D digital core with a fully convolutional neural network

In this paper, the complete process of constructing 3D digital core by full convolutional neural network is described carefully. A large number of sandstone computed tomography (CT) images are used as training input for a fully convolutional neural network model. This model is used to reconstruct the three-dimensional (3D) digital core of Berea sandstone based on a small number of CT images. The Hamming distance together with the Minkowski functions for porosity, average volume specific surface area, average curvature, and connectivity of both the real core and the digital reconstruction are used to evaluate the accuracy of the proposed method. The results show that the reconstruction achieved relative errors of 6.26%, 1.40%, 6.06%, and 4.91% for the four Minkowski functions and a Hamming distance of 0.04479. This demonstrates that the proposed method can not only reconstruct the physical properties of real sandstone but can also restore the real characteristics of pore distribution in sandstone, is the ability to which is a new way to characterize the internal microstructure of rocks.

Synthesis and Characterization of Multi‐Modal γ‐Al2O3: A Systematic Investigation on the Optimization of Hydrodemetallization Catalyst Preparation

AbstractThe pore structure of hydrodemetallization catalysts plays a vital role in their lifetime and thus, on the process economy. In this investigation, a multi‐modal meso and macroporous alumina has been prepared by using aluminum alkoxides. To tune the alumina properties to the desired values, a systematic design of experiments was applied to propose correlations between the synthesis parameters and catalyst properties. Several factors, which are effective on the specifications of the prepared multi‐modal alumina, were analyzed and the dominant factors were identified. The results predicted by the model were in agreement with the experimental data. The analysis of the results showed that the prepared optimal sample had an average pore diameter and specific surface area of 21.2 nm and 341 m2/gr, respectively. For the prepared catalyst, N2 adsorption/desorption measurements showed a multimodal pore structure ranging from 2 to 100 nm in size.Finally, an HDM catalyst was prepared based on optimum alumina. The activity and performance of the prepared catalyst were compared with those of the commercial catalyst. At low space times, V‐TPP conversion for commercial and prepared catalysts were 38.9 and 49.5 percent, respectively, showing a higher activity for the prepared catalyst.

Experimental investigation on the effect of ethanol on micropore structure and fluid distribution of coalbed methane reservoir

The development of coalbed methane not only ensures the supply of natural gas but also reduces the risks of coal mine accidents. The micropore structure of coalbed methane reservoir affects the seepage of coalbed methane; improvement of pore structure is one of the effective methods to enhance the efficiency of coalbed methane exploitation. In this study, low-pressure nitrogen gas adsorption, specific surface area analysis, nuclear magnetic resonance spectroscopy, and centrifugation experiment were used to evaluate the effect of ethanol on coal microscopic pore structure and fluid distribution during hydraulic fracturing. Seven coal samples were collected from the No. 3 coal seam in Zhaozhuang Mine, Qinshui Basin. The samples are mainly composed of micropores, transition pores, and mesopores. The experimental results show that ethanol can significantly change the pore structure by increasing the pore diameter. The average specific surface area, pore volume, and pore diameter of rock samples before ethanol immersion are 1.1270 m2/g, 0.0104 cm3/g, and 14.20 nm, respectively. The three parameters of rock samples after ethanol immersion are 0.5865 m2/g, 0.0025 cm3/g, and 29.37 nm. Ethanol improves the connectivity between micropores and mesopores. The average irreducible fluid saturation of samples saturated with formation water after centrifugation is 86%, and the average irreducible fluid saturation of samples soaked in three concentrations of ethanol solution decreases. It is considered that an ethanol solution of 0.4% concentration has the best effect on improving the pore structure and fluid distribution.

Carbon-encapsulated MnFe2O4 nanoparticles: effects of carbon on structure, magnetic properties and Cr(VI) removal efficiency

In this work, the influences of carbon on structure, magnetic properties and Cr(VI) absorption efficiency of carbon-encapsulated MnFe2O4 nanoparticles (MFO/C NPs) are studied. SEM images indicate that the fabricated MnFe2O4 nanoparticles (MFO NPs) are enveloped by carbon layers, forming encapsulating structure. By the BET analysis, it is demonstrated that the average specific surface area of MFO/C samples is higher than that MFO sample. From FTIR and XPS spectra, the presence of carbon-coated MnFe2O4 nanoparticles is confirmed. It is found that the Cr(VI) absorption efficiency of the MFO/C NPs first increases to reach the maximum value at 5% C concentration, and then decreases with the further increment of C concentration. The maximum absorption efficiency and capacity of 90.1% and 73.26 mg/g are obtained, respectively. Finally, a removal mechanism for the removal of Cr(VI) is proposed. The obtained results demonstrate that the carbon-encapsulated MnFe2O4 NPs is a promising candidate as an advanced absorbent for the removal of Cr(VI) from wastewater.