Low-temperature N2 Adsorption Research Articles

Liquid-phase adsorption of nitrogen compounds from model diesel fuel on activated carbons

One of the great challenges in deep hydrodesulfurization (HDS) to produce ultra-low-sulfur diesel (ULSD) is the coexisting heterocyclic nitrogen-containing compounds in middle distillates, which significantly inhibit the HDS reactions. This study investigates various activated carbon (AC) samples for selectively removing nitrogen compounds from a model diesel fuel through adsorption. The physical and chemical properties of the AC samples were characterized using low-temperature N2 adsorption–desorption, SEM–EDS, and FT-IR to explore their impact on the adsorption performance. The results indicate that the adsorption performance is influenced not only by the surface area and by the number of oxygen-containing functional groups on the surface but also by the pore diameter distribution. Among all AC samples tested, AC-W exhibited the highest adsorption capacity, achieving a nitrogen removal rate of 97.8% with the addition of 10 wt.% of AC-W. The adsorption capacity was approximately 24.0 mg-N/g-A at a nitrogen equilibrium concentration of 200 ppmw. The adsorption isotherms for total nitrogen and individual nitrogen compounds in the fuel over AC can be described well by the Freundlich isotherm model. An approach for improving the ADN performance of AC is discussed based on the findings in this study.

Reformation of coal reservoirs by microorganisms and its significance in CBM exploitation

The study investigates the variations in surface morphology and micro-nano-scale pore structure of coal matrix during the process of biodegradation. Comprehensive reservoir characterization techniques, including field emission scanning electron microscope, mercury intrusion porosimetry, and low-temperature N2 adsorption, are employed on four anthracite samples. The significance of the relationship between coal reservoir bio-reformation and coalbed methane (CBM) exploitation is proposed. The main findings indicate that organic matter on the surface of the coal matrix can undergo biodegradation, resulting in the generation of new pores. Microbial metabolism does not alter pore type but only modifies pore size and volume of coal. After microbial degradation, there is an increase in average pore width, while both Brunauer-Emmett-Teller specific surface area and Barrett-Joyner-Halenda pore volume decrease. Furthermore, bioconversion leads to a reduction in both surface and volume dimensions of coal, resulting in a smoother coal matrix surface and simplified complexity of its pore structure. This benefits desorption, migration, and exploitation of CBM. These findings further reinforce the pivotal role of microbial-enhanced coalbed methane production technology in improving CBM production and promoting the clean utilization of coal resources.

Carbon Dioxide Utilization Using Plasma Reactor Packed with Magnesia-Ceria Catalysts with Various Morphology

A series of CeO2–MgO catalysts with different molar ratio was prepared for the plasma-activated CO2 decomposition to CO and O2. The catalysts were synthesized by the sol-gel method and characterized by physicochemical methods (XRD, SEM, XPS, low-temperature N2 adsorption, CO2-TPD). The highest CO2 conversion (31%) was achieved in the presence of the catalyst with the highest CeO2 content. The addition of H2 into a CO2 decomposition system was also studied. No CO2 methanation occurred in the presence of synthesized catalysts, though an increase in the CO2-to-CO conversion was observed due to an increase of a discharge power in the presence of molecular hydrogen.

Cordierite-Supported Transition-Metal-Oxide-Based Catalysts for Ozone Decomposition

Cordierite-based supported noble-metal-free catalysts for ozone decomposition are elaborated. The cordierite ceramic surface is pretreated with oxalic acid and NaOH, and Mn-Cu-Ni oxide catalysts are prepared by the impregnation method. The mass ratio of the supported oxides in the resulting catalysts is MnO2:CuO:NiO = 3:2:1, and their loadings are from 1.8 to 7.0 wt.%. The pretreated supports and catalysts are characterized by low-temperature N2 adsorption, scanning electron microscopy (SEM), powder X-ray diffraction analysis (XRD), and temperature-programmed reduction with H2 (TPR-H2). The catalysts are tested in ozone decomposition with high airflow rates (20 and 50 L/min) and with initial ozone concentrations of 1 and 2 ppm at temperatures in the range of 25–120 °C. It is shown that a combined treatment of cordierite with oxalic acid and NaOH leads to a developed porous structure and stabilization of supported Mn-Cu-Ni oxides in a highly dispersed state. The high activity of catalysts in ozone decomposition at room temperature and high airflow is demonstrated. The developed catalysts can be recommended for application in purification of air from the ozone because of their high catalytic activity, high mechanical stability, and relatively low weight and cost.

Greenhouse Gas Conversion into Hydrocarbons and Oxygenates Using Low Temperature Barrier Discharge Plasma Combined with Zeolite Catalysts

Global warming occurs as a result of the build-up of greenhouse gases in the atmosphere, causing an increase in Earth’s average temperature. Two major greenhouse gases (CH4 and CO2) can be simultaneously converted into value-added chemicals and fuels thereby decreasing their negative impact on the climate. In the present work, we used a plasma-catalytic approach for the conversion of methane and carbon dioxide into syngas, hydrocarbons, and oxygenates. For this purpose, CuCe zeolite-containing catalysts were prepared and characterized (low-temperature N2 adsorption, XRF, XRD, CO2-TPD, NH3-TPD, TPR). The process of carbon dioxide methane reforming was conducted in a dielectric barrier discharge under atmospheric pressure and at low temperature (under 120 °C). It was found that under the studied conditions, the major byproducts of CH4 reforming are CO, H2, and C2H6 with the additional formation of methanol and acetone. The application of a ZSM-12 based catalyst was beneficial as the CH4 conversion increased and the total concentration of liquid products was the highest, which is related to the acidic properties of the catalyst.

Gas production decline trends for Longmaxi shale under thermally stimulated conditions

Recently, thermal treatment has emerged as a promising technology to enhance shale gas recovery efficiency by promoting gas desorption. However, the understanding of gas desorption characteristics from heterogeneous shale matrix under thermal stimulation remains inadequate, which constrains the development of thermal recovery technology. In this study, on-site canister desorption tests were employed to investigate the shale gas desorption patterns of four distinct shale cores, sourced from four various production zones, under two heating stages (50 °C and 110 °C). Additionally, low-temperature N2 adsorption experiments and infrared examination were used to study the microstructure characteristics of shale before and after thermal treatments. The canister desorption tests revealed that the gas production rates increased for all shales under heating conditions, particularly when transitioning from 50 °C to 110 °C. However, the peak gas production rates at the two heating stages exhibited different trends: nearly identical for Shale-1 and Shale-2, decreasing for Shale-3 and increasing for Shale-4. This can be attributed to the different quantities of adsorbed gas present in shale samples, with Shale-4 containing approximately 0.0088 m3, compared to the markedly lower volumes in Shale-1 (0.0053 m3), Shale-2 (0.0040 m3), and Shale-3 (0.0041 m3). Furthermore, the gas production rates followed distinct decline trends at different temperatures: exponentially at 50 °C and following a power law at 110 °C, indicating varying gas desorption dynamics under different thermal conditions. Moreover, the findings from low-temperature N2 adsorption experiments and infrared examination indicated that combustion increased the pore volume and induced thermal cracks and fractures, thereby enhancing shale permeability. These insights highlight the potential of combustion fracturing as a technology to improve gas recovery efficiency.

Effect of TiO2 on Pd/La2O3-CeO2-Al2O3 Systems during Catalytic Oxidation of Methane in the Presence of H2O and SO2.

New results on the effect of TiO2 on Pd/La2O3-CeO2-Al2O3 systems for catalytic oxidation of methane in the presence of H2O and SO2 have been received. Low-temperature N2-adsorption, XRD, SEM, HRTEM, XPS, EPR and FTIR techniques were used to characterize the catalyst. The presence of Ce3+ on the catalytic surface and in the volume near the lantana was revealed by EPR and XPS. After aging, the following changes are observed: (i) agglomeration of the Pd-clusters (from 8 nm to 12 nm); (ii) transformation of part of the TiO2 from anatase to larger particles of rutile; and (iii)-the increase in PdO/Pd-ratio above its optimum. The modification by Ti of the La2O3-CeO2-Al2O3 system leads to higher resistance towards the presence of SO2 most likely due to the prevailing formation of unstable surface sulfites instead of thermally stable sulfates. Based on kinetic model calculations, the reaction pathway over the Pd/La2O3-CeO2-TiO2-Al2O3 catalyst follows the Mars-van Krevelen mechanism. For evaluation of the possible practical application of the obtained material, a sample of Pd/La2O3-CeO2-TiO2-Al2O3, supported on rolled aluminum-containing stainless steel (Aluchrom VDM®), was prepared and tested. Methane oxidation in an industrial-scale monolithic reactor was simulated using a two-dimensional heterogeneous reactor model.

Effect of Pore Size Distribution on Energy Storage of Nanoporous Carbon Materials in Neat and Dilute Ionic Liquid Electrolytes.

This study investigates three carbide-derived carbon (CDC) materials (TiC, NbC, and Mo2C) characterized by uni-, bi-, and tri-modal pore sizes, respectively, for energy storage in both neat and acetonitrile-diluted 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. A distribution of micro- and mesopores was studied through low-temperature N2 and CO2 adsorption. To elucidate the relationships between porosity and the electrochemical properties of carbon materials, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy measurements were conducted using three-electrode test cells. The ultramicroporous TiC-derived carbon is characterized by a high packing density of 0.85 g cm-3, resulting in superior cathodic and anodic capacitances for both neat ionic liquid (IL) and a 1.9 M IL/acetonitrile electrolyte (93.6 and 75.8 F cm-3, respectively, in the dilute IL). However, the bi-modal pore-sized microporous NbC-derived carbon, with slightly lower cathodic and anodic capacitances (i.e., 85.0 and 73.7 F cm-3 in the dilute IL, respectively), has a lower pore resistance, making it more suitable for real-world applications. A symmetric two-electrode capacitor incorporating microporous CDC-NbC electrodes revealed an acceptable cycle life. After 10,000 cycles, the cell retained approximately 75% of its original capacitance, while the equivalent series resistance (ESR) only increased by 13%.

Nanopore Structure and Multifractal Characteristics of Continental Shale Oil Reservoir: A Case Study from Ziliujing Shales in the Sichuan Basin

Thermal maturity of the shales from the Ziliujing Formation of the Jurassic age in the Sichuan Basin is in the hydrocarbon generation window, which makes it a candidate for shale oil and gas development. The meso- and macropore characteristics and heterogeneity of shales are important factors affecting the occurrence and development of oil and gas. However, the meso- and macropores of the Ziliujing shales have not been systematically studied. Thus, the mineral compositions and total organic carbon (TOC) of samples from this formation, as well as its pore structure, are analyzed by low-temperature N2 adsorption technique. Moreover, the heterogeneity of the pores was determined by multifractal analysis. The results show that the Ziliujing shales can be classified into three types according to the distributions of mineral compositions of carbonate and mixed and argillaceous shales. Results revealed that the smallest meso- and macropore volume (PV), the smallest specific surface area (SSA), and the largest average pore diameter (APD) occur in the carbonate shales. However, the largest PV and SSA and the smallest APD are observed in the argillaceous shales. The porosity of carbonate shales is mainly concentrated between 5 nm and 30 nm. Compared with carbonate shales, the porosity with pore sizes less than 30 nm of mixed and argillaceous shales shows a rapid increase. Furthermore, inorganic minerals are the main factors affecting the pore distributions, while TOC shows a weak effect. Herein, clay minerals significantly increase the mesopore volume and the pore number with a size of less than 30 nm. The Dq-q curves reveal that the meso- and macropore distributions of Ziliujing shales show multifractal behavior, but the multifractal characteristics of pores of various shales are distinctly different. The information dimension D1, the Hurst exponent H, and the width of the right side D0–D10 are key indicators to distinguish the local variations within the pore structure of different types of shales. The carbonate shales have the largest multifractal spectra width and the smallest D1 and H, while the opposite trend is found for the argillaceous shales. Clay minerals reduce the heterogeneity of the meso- and macropore distributions and increase the pore connectivity. Nevertheless, the carbonate minerals exhibit a reverse trend. Finally, it was found that TOC does not impact pore complexity as much. Collectively, this study supports our understanding of the occurrence of shale oil within various reservoir facies, thereby providing a guideline for future explorations in the Ziliujing Formation of the Jurassic age in the Sichuan Basin.

Silica-titania mesoporous silicas of MCM-41 type as effective catalysts and photocatalysts for selective oxidation of diphenyl sulfide by H2O2

Abstract Spherical Ti-MCM-41, synthetized by co-condensation method, presented very promising activity in catalytic and photocatalytic oxidation of diphenyl sulfide with H2O2 to obtain diphenyl sulfoxide and diphenyl sulfone. Mesoporous silica materials with various titanium content were analyzed with respect to chemical composition (inductively coupled plasma optical emission spectrometry), structure properties (X-ray diffraction), textural properties (low-temperature N2 adsorption–desorption), morphology (scanning electron microscopy), forms and aggregation introduced titanium species (diffuse reflectance spectroscopy, Raman spectroscopy), and surface acidity (NH3-TPD). Titanium introduced in the samples was present mainly in the form of highly dispersed species, presenting catalytic and photocatalytic activities in diphenyl sulfide oxidation with H2O2. Efficiency of the reaction increased with an increase in titanium loading in the samples and was significantly intensified under UV irradiation. The role of various Ti species in diphenyl sulfide oxidation was presented and discussed.

Influence of supercritical CO2 on fracture network evolution with nanopore structure linkage in high-rank anthracite matrix

It is essential to understand the permeability evolution of coal reservoirs under the interaction of supercritical CO2 (SC-CO2) in order to be successful in both CO2 geological storage and extraction of coalbed methane. However, the influence of nanopore structure characteristics on the permeability evolution of coal exposed to SC-CO2 has not been elucidated. To this end, the quantitative analysis of the pores in high-rank coal was conducted through low-temperature N2 adsorption, low-temperature CO2 adsorption, and Nuclear Magnetic Resonance (NMR). The analysis revealed that micropores and mesopores are the major contributors to the specific surface area and pore volume of the nanopores, respectively. After SC-CO2 interaction, the pore size and pore number of the coal increased significantly, with small pores changing to large ones, mainly due to the dissolution of SC-CO2 with the contribution of gas pressure being negligible. The proportion of micropore and mesopore decreases while that of macropore increases after SC-CO2 treatment, especially SC-CO2 causes macropores to be continuous and increased the connectivity of fractures. The relationship between nanopore structure characteristics and the deformation of the fracture network under SC-CO2 interaction was studied. The results showed that the specific surface area (SSA) of the micropore and the volume fractal dimension (DLN2) of the mesopore were related to the change of fracture porosity, while the surface fractal dimension (DLN1) of the micropore, the specific surface area (SSA) and pore volume of mesopore were related to the change of fracture complexity. This indicated that the evolution of the fracture network under SC-CO2 interaction is related to the nanopore structure characteristics. A mechanical model was established based on the close correlation between nanopore structures characteristics in the matrix and the evolution of fracture networks under SC-CO2 interaction. This mechanical model elucidates the impact of nanopore alteration resulting from mineral dissolution induced by SC-CO2 on the evolution of fracture networks. This research provides a clearer understanding of the evolution in reservoir permeability during CO2 geological sequestration, offering valuable reference for safety assessments.

Influence of pseudoboehmite properties on characteristics of CoMo/ASA-Al2O3 catalysts for selective hydrotreating of FCC gasoline

The influence of alumina precursor (pseudoboehmites) in CoMo/ASA + Al2O3 catalysts on catalytic activity in FCC gasoline hydrotreating has been studied. Pseudoboehmites prepared by alcoholate, precipitate and hydrothermal technologies were used. Parent powders, supports and catalysts were characterized by low-temperature N2 adsorption, TPD of ammonia, STEM, HRTEM, UV–vis spectroscopy. Catalysts were tested in hydrotreating of the model FCC gasoline feedstock. It is shown that the choice of pseudoboehmite has significant effect on textural, acid and mechanical properties of supports and catalysts, as well as dispersity of the active phase. The type of pseudoboehmite affects the amount of tetrahedral cobalt in catalysts that changes surface activity per 1 g of the catalyst. The linear dependence between the ratio of the medium and weak acid sites and catalyst selectivity was found. It is established that isomerizing activity is higher than the hydrogenating one, when medium/weak acid sites ratio in the catalyst is lower than 1.85.

Paleo-Environment Induced Full-Scale Pore Variation in the Low Matured Shale: A Case Study of the Third Member of the Jiufotang Formation at the Lujiapu Rift Basin, Northeast China

Shale in the third member of the Jiufotang Formation at the Lujiapu Rift Basin is a new potential target for shale oil exploration and has rarely been studied before. In order to study pore structure and its controlling factors, shale compositions are mainly analyzed by X-ray Diffraction (XRD), and the characterization of full-scale pore structures is studied by the field-emission scanning electron microscope (FE-SEM), low-temperature N2 adsorption, and high-pressure mercury intrusion porosimetry (high-pressure MIP). According to composition and micro-texture, shale samples in the third member of the Jiufotang Formation are classified into three types: laminated organic matter-lean shale (TOC < 2%), unlaminated organic matter-intermediate shale (2% < TOC < 4%) and laminated organic matter-rich shale (TOC > 4%). Most shale samples are dominated by interparticle pores, with many of them filled by diagenetic minerals. All the shale samples are most developed in mesopores, whose development is mainly controlled by quartz content. And macropores with a diameter of 10,000 nm~100,000 nm are the secondary developed pores, which are influenced by both the paleoenvironment and diagenesis (especially clay transformation). Full-scale pore variations in laminated organic matter-lean shale, unlaminated organic matter-intermediate shale, and laminated organic matter-rich shale are ultimately related to their paleoenvironments.

Highly Efficient RGO-Supported Pd Catalyst for Low Temperature Hydrocarbon Oxidation

The work presents Pd-containing catalysts for practical application with enhanced low-temperature activity in the complete oxidation of volatile organic compounds (VOCs) using innovative combinations of reduced graphene oxide (RGO) and alumina. The catalysts were characterized by XRD, SEM, TEM, XPS, low-temperature N2-adsorption, and CO chemisorption. The tests on complete catalytic oxidation of different VOC (propane, butane, hexane, dimethyl ether, toluene, propylene) and CO were carried out. The reaction kinetics and the mechanism of the reaction of complete oxidation of toluene are being investigated in detail. The results show that the new catalyst design makes it able to completely oxidize the studied VOCs and CO at low temperatures (100–350 °C) with long-term stability. Using a variety of instrumental methods, it was established that for high activity and long-term stability, the optimal ratio Pd/PdO should be close to 1:1. The most probable mechanism of complete toluene oxidation is the mechanism of Langmuir–Hinshelwood. The high activity and the weak effect of water on the catalyst performance leads to further perspectives for the application of the currently developed approach for the preparation of large-scale monolithic catalytic systems for air pollution control.

Experimental Investigation on the Impact of Coal Fines Migration on Pores and Permeability of Cataclastic Coal.

During the production process of coalbed methane, the generation and migration of coal fines can obstruct fractures in coal reservoirs and reduce their permeability. In order to investigate the effects of coal fines migration on the porosity and permeability of coal reservoirs, we conducted core water flooding experiments, low-field nuclear magnetic resonance (NMR), and low-temperature N2 adsorption experiments to study the variations in porosity and permeability of cataclastic coal during coal fines migration and the impact of coal fines migration on porosity and permeability. The experimental results reveal that the initial porosity ratio of cataclastic coal exhibits the characteristics of micropore > macropore > transitional pore > mesopore, with the pore types being predominantly fissured. The porosity of pores larger than 1000 nm and those larger than 10,000 nm exhibit consistent trends before and after water flooding, indicating that the blockage or unblocking of pores with radius larger than 10,000 nm by coal fines can also cause blockage or unblocking of some interconnected macropore. The early stage of flooding is the main period for coal fines migration and production in cataclastic coal, during which the mass concentration of coal fines production is higher and some macropores and fractures become blocked, resulting in a larger decrease in porosity. The higher the initial permeability of cataclastic coal samples with a larger end-face fracture density, the more similar the variations in porosity and permeability of pores larger than 10,000 nm during the flooding experiment, indicating that coal fines mainly block interconnected pores and fractures with radius larger than 10,000 nm through migration, thereby reducing permeability. This study provides a theoretical basis for the efficient production of coalbed methane.

Evolution Characteristics of the Microstructure with Different Fracturing Fluids: An Experimental Study of Guizhou Bituminous Coal.

Fracturing fluid is a key factor affecting the hydraulic fracture morphology and coal microstructure, which plays a key role in the hydraulic fracturing effect. To compare the effect of clean water, clean fracturing fluid, and acid fracturing fluid on the pore structure of coal, this paper used high-pressure mercury injection (MIP), low-temperature N2 adsorption (LT-N2A), and scanning electron microscopy (SEM) to determine the pore structure of Guizhou bituminous coal before and after the action of fracturing fluid. The results show that clean water can cause mineral expansion and reduce pore volume by about 6% and clean fracturing fluid and acid fracturing fluid can increase pore volume by 3 and 12%, respectively, due to different degrees of acidity. The MIP data show that the pore structure of coal samples is more complex after the action of different fracturing fluids, and acidic fracturing fluids can increase the fractal dimension of the pore by about 7%. The LT-N2A data showed that the fractal dimension of micropores and transition pores decreased after the action of different fracturing fluids. In general, acid fracturing fluid has the best effect on the coal microstructure, followed by clean fracturing fluid, and the least effect on clean water.

Multicomponent digital core construction and three-dimensional micro-pore structure characterization of shale

The components and pore structure of shale are complex due to the heterogeneous distribution of organic matter and the complex distributions of the minerals. The digital core, possessing the advantages of being economical and reusable, can be widely used to directly characterize the three dimensional (3D) micro-pore structure and to numerically simulate its physical properties. During construction of a digital shale core, it is a challenge to solve the multicomponent segmentation for the digital shale core, the contradiction between the sample size and image resolution, and the identification of the pore types in the 3D pore space. Therefore, an automatic workflow based on the gray gradient-maximum entropy-3D morphology was developed. The gray gradient-maximum entropy algorithm was used to segment each sub-image of focused ion beam scanning electron microscope images to generate segmented images. On this basis, the pore size distribution was optimized via 3D morphological erosion. Based on the concept of pore clusters, the organic and inorganic pores were identified using the 3D morphological method for the first time. The construction of a multicomponent digital shale core was realized. The 3D micro-pore structure of the organic and inorganic pores was characterized by pore connectivity, heterogeneity, and pore size distribution. The accuracy of the proposed method was verified using low-temperature N2 adsorption experiment data. The results of this study provide new insight into the multicomponent digital shale core construction and lay the foundation for the characterization of the petrophysical properties and micro-/nano-scale fluid flow simulations of shale.

Ciprofloxacin Adsorption onto a Smectite–Chitosan-Derived Nanocomposite Obtained by Hydrothermal Synthesis

The employment of compounds obtained from natural sources to produce adsorbents and their application in the elimination of antibiotics from industrial effluents have gained significant attention because of their low production cost and sustainability. Herein, chitosan (biopolymer) and smectite (abundant clay mineral) were used for the low-cost and eco-friendly synthesis of a new type of adsorbent. A low-energy-consumption hydrothermal process was applied to the synthesis of the chitosan-derived carbon–smectite nanocomposite with cobalt (H_Co/C-S). The produced nanocomposite was characterized using elemental analysis, ICP-OES, XRPD, low-temperature N2 adsorption–desorption isotherms, FTIR analysis, and point of zero charge. H_Co/C-S (SBET = 0.73 m2 g−1, d001 = 1.40 nm, pHPZC = 5.3) was evaluated as a ciprofloxacin adsorbent in aqueous solution. Experimental data were fitted with different kinetic models and interpreted by selected adsorption isotherms. The pseudo-second-order model was found to be the most appropriate, while ciprofloxacin adsorption onto H_Co/C-S was best described by the Redlich–Peterson isotherm (R2 = 0.985). The maximum adsorption capacity of H_Co/C-S, according to the Langmuir isotherm (R2 = 0.977), was 72.3 mg g−1. Desorption and thermodynamic studies were performed. The obtained results indicated that the new hierarchically designed H_Co/C-S has promising potential to be further tested for application in real wastewater treatment.

Advantages of Structure and Electrochemical Properties of Graphene Prepared from Tectonically Deformed Coal.

Asa low-cost carbon-rich resource, coal has been widely used to prepare excellent electrochemical energy-storage carbon materials such as graphene. However, the different structures of carbon source will affect the performance of carbon materials. To explore the feasibility of preparing high-performance graphene from the carbon source affected by tectonic stress in coal, in this paper, series products of coal-based graphene are prepared by tectonically deformed coal (TDC) and normal structural coal (NSC). The structural parameters are characterized by HRTEM, XRD, Raman, and low-temperature CO2 and N2 adsorption, and the electrochemical performance of coal-based graphene lithium battery is tested by galvanostatic charge-discharge and cyclic voltammetry. The results show that tectonic stress makes the proportion of the medium-long aromatic fringes, preferred orientation degree (POD), and multilayer stacking in TDC aromatic fringes slightly higher than those in NSC. At the same temperature, the relatively large microcrystalline size, the high order degree, and more pore structures make the local molecular oriented (LMO) domain vertical height (d) and graphitization degree (G) of the coal-based graphite microcrystalline structure prepared by TDC better than those of NSC, which indicates that the carbon source in TDC contains more graphitizable carbon structures. This makes the graphene prepared by TDC not only possess perfectly ordered crystal planes but also relatively abundant nanochannels. High lithium-storage capacity and low charge-transfer resistance make the electrochemical performance of graphene prepared by TDC as an anode electrode material for lithium-ion batteries superior to that by NSC.

Magnetic Carbon Nanocomposites: Preparation from Cellulose via Chemical Activation with FeCl3 and Characterization

We have studied the preparation of magnetic graphitic carbon composites, which combine the adsorption properties of activated carbon with magnetic properties and properties intrinsic to graphite. The preparation method is efficient; it comprises modifying flax shive cellulose with citric acid to enhance the chelating ability of the flax shive cellulose matrix, impregnating the modified cellulose with iron chloride, and pyrolysis in an inert atmosphere to control the composition, morphology, specific surface, and porosity of hybrid carbon materials. The scenario of cellulose matrix pyrolysis was suggested using thermogravimetry. X-ray structural analysis was used to characterize the graphitic composites. The citric acid modification of cellulose helps to prepare a high-graphite (74%) carbon composite where the graphitization level of the graphite structure approaches the graphitization level of commercially available graphite at 700°С. Low-temperature N2 adsorption–desorption and ζ-potential measurements helped to suggest the adsorption mechanism for environmentally hazardous dyes. The greatest equilibrium adsorption of Methylene Blue (MB) and Methyl Orange (MO) dyes was 127.4 and 23.7 mg/g, respectively. The prepared composites can be used as adsorbents and fillers in polymer composite materials.