Preparation of Activated Carbons from Lignite for Electrochemical Capacitors by Microwave and Electrical Furnace Heating

2011 ◽  
Vol 194-196 ◽  
pp. 2472-2479 ◽  
Author(s):  
Bao Lin Xing ◽  
Chuan Xiang Zhang ◽  
Lun Jian Chen ◽  
Guang Xu Huang
Keyword(s):  
Specific Surface ◽  
Specific Capacitance ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Electrochemical Capacitors ◽  
Weight Ratio ◽  
Total Pore Volume ◽  
Electrochemical Performances

Activated carbons (ACs) were prepared from lignite by microwave (MW) and electrical furnace (EF) heating with KOH as activation agent. In order to compare pore structures and electrochemical performances of ACs prepared by both heating methods, the ACs were characterized by N2 adsorption at 77K, X-ray diffraction (XRD) and scanning electron microscope (SEM). The electrochemical performances of Electrochemical capacitors (ECs) with ACs as electrodes in 3mol/L KOH electrolyte were evaluated by constant current charge-discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the pore structures of ACs prepared by MW and EF heating significantly enhance when the weight ratio of KOH to coal increases from 2 to 4. The BET specific surface area, total pore volume, the ratio of mesopore and average pore diameter of ACs prepared by MW heating (denoted as AC-MW4) reaches 2094m2/g, 1.193cm3/g, 53.6%, 2.28nm when the weight ratio of KOH to coal is 4, and ACs prepared by EF heating (denoted as AC-EF4) reaches 2580m2/g, 1.683cm3/g, 67.3%, 2.61nm. The ECs with AC-MW4 and AC-EF4 as electrodes present a high specific capacitance of 348F/g and 377F/g at a current density of 50mA/g, and still remain 325F/g and 350F/g after 500 cycles, respectively. Although the specific surface area, total pore volume and specific capacitance of ACs prepared by MW heating are slightly lower than EF heating, taking into account the heating time in the activation process, ACs prepared by EF heating needs approximate 140min, while MW heating only needs 10min, which have demonstrated that microwave heating technology is a promising and efficient technique to prepare ACs.

scholarly journals Activated Carbons from Thermoplastic Precursors and Their Energy Storage Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 896 ◽  
Author(s):  
Hye-Min Lee ◽  
Kwan-Woo Kim ◽  
Young-Kwon Park ◽  
Kay-Hyeok An ◽  
Soo-Jin Park ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Field Emission ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Cross Linking ◽  
Mesopore Volume

In this study, low-density polyethylene (LDPE)-derived activated carbons (PE-AC) were prepared as electrode materials for an electric double-layer capacitor (EDLC) by techniques of cross-linking, carbonization, and subsequent activation under various conditions. The surface morphologies and structural characteristics of the PE-AC were observed by field-emission scanning electron microscope, Cs-corrected field-emission transmission electron microscope, and X-ray diffraction analysis, respectively. The nitrogen adsorption isotherm-desorption characteristics were confirmed by Brunauer–Emmett–Teller, nonlocal density functional theory, and Barrett–Joyner–Halenda equations at 77 K. The results showed that the specific surface area and total pore volume of the activated samples increased with increasing the activation time. The specific surface area, the total pore volume, and mesopore volume of the PE-AC were found to be increased finally to 1600 m2/g, 0.86 cm3/g, and 0.3 cm3/g, respectively. The PE-AC also exhibited a high mesopore volume ratio of 35%. This mesopore-rich characteristic of the activated carbon from the LDPE is considered to be originated from the cross-linking density and crystallinity of precursor polymer. The high specific surface area and mesopore volume of the PE-AC led to their excellent performance as EDLC electrodes, including a specific capacitance of 112 F/g.

scholarly journals Effect of Mesopore Development on Butane Working Capacity of Biomass-Derived Activated Carbon for Automobile Canister

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 673
Author(s):  
Byeong-Hoon Lee ◽  
Hye-Min Lee ◽  
Dong Chul Chung ◽  
Byung-Joo Kim
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Volume Fraction ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Working Capacity ◽  
Activation Time

Kenaf-derived activated carbons (AKC) were prepared by H3PO4 activation for automobile canisters. The microstructural properties of AKC were observed using Raman spectra and X-ray diffraction. The textural properties were studied using N2/77 K adsorption isotherms. Butane working capacity was determined according to the ASTM D5228. From the results, the specific surface area and total pore volume of the AKC was determined to be 1260–1810 m2/g and 0.68–2.77 cm3/g, respectively. As the activation time increased, the butane activity and retentivity of the AKC increased, and were observed to be from 32.34 to 58.81% and from 3.55 to 10.12%, respectively. The mesopore ratio of activated carbon increased with increasing activation time and was observed up to 78% at 973 K. This indicates that butane activity and retentivity could be a function not only of the specific surface area or total pore volume, but also of the mesopore volume fraction in the range of 2.8–3.8 nm and 5.5-6.5 nm of adsorbents, respectively. The AKC exhibit enhanced butane working capacity compared to commercial activated carbon with the high performance of butane working capacity due to its pore structure having a high mesopore ratio.

scholarly journals Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 298
Author(s):  
Chenlong Ding ◽  
Jinxian He ◽  
Hongchen Wu ◽  
Xiaoli Zhang
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Shale Gas ◽  
Pore Volume ◽  
Ordos Basin ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Taiyuan Formation

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

scholarly journals Structural and fractal characterization of adsorption pores of middle–high rank coal reservoirs in western Yunnan and eastern Guizhou: An experimental study of coals from the Panguan syncline and Laochang anticline

2018 ◽  
Vol 37 (1) ◽  
pp. 251-272 ◽  
Author(s):  
Junjian Zhang ◽  
Chongtao Wei ◽  
Gaoyuan Yan ◽  
Guanwen Lu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Structural Parameters ◽  
Total Pore Volume ◽  
Type A ◽  
Type B ◽  
Type C

To better understand the structural characteristic of adsorption pores (pore diameter < 100 nm) of coal reservoirs around the coalbed methane production areas of western Yunnan and eastern Guizhou, we analyzed the structural and fractal characteristics of pore size range of 0.40–2.0 nm and 2–100 nm in middle–high rank coals ( Ro,max = 0.93–3.20%) by combining low-temperature N2/CO2 adsorption tests and surface/volume fractal theory. The results show that the coal reservoirs can be divided into three categories: type A ( Ro,max < 2.15%), type B (2.15% <  Ro,max <2.50%), and type C ( Ro,max > 2.15%). The structural parameters of pores in the range from 2 to 100 nm are influenced by the degree of coal metamorphism and the compositional parameters (e.g., ash and volatile matter). The dominant diameters of the specific surface areas are 10–50 nm, 2–50 nm, and 2–10 nm, respectively. The pores in the range from <2 nm provide the largest proportion of total specific surface area (97.22%–99.96%) of the coal reservoir, and the CO2-specific surface area and CO2-total pore volume relationships show a positive linear correlation. The metamorphic degree has a much greater control on the pores (pore diameter less than 2 nm) structural parameters than those of the pore diameter ranges from 2 to 100 nm. Dv1 and Dv2 can characterize the structure of 2–100 nm adsorption pores, and Dv1 (volume heterogeneity) has a positive correlation with the pore structural parameters such as N2-specific surface area and N2-total pore volume. This parameter can be used to characterize volume heterogeneity of 2–10 nm pores. Dv2 (surface heterogeneity) showed type A > type B > type C and was mainly affected by the metamorphism degree. Ds2 can be used to characterize the pore surface heterogeneity of micropores in the range of 0.62–1.50 nm. This parameter has a good correlation with the pore parameters (CO2-total pore volume, CO2-specific surface area, and average pore size) and is expressed as type C < type B < type A. In conclusion, the heterogeneity of the micropores is less than that of the meso- and macropores (2–100 nm). Dv1, Dv2, and Ds2 can be used as effective parameters to characterize the pore structure of adsorption pores. This result can provide a theoretical basis for studying the pore structure compatibility of coal reservoirs in the region.

The Influence of Sinterng Temperature on the Phase, Microstructure and Textual Properties of Hollow Hydroxyapatite Microspheres

2011 ◽  
Vol 239-242 ◽  
pp. 2274-2279 ◽  
Author(s):  
Ying Chun Wang ◽  
Wen Hai Huang ◽  
Ai Hua Yao ◽  
De Ping Wang
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Sintering Temperature ◽  
Total Pore Volume ◽  
Precipitation Method ◽  
Simple Method ◽  
Air Atmosphere

A simple method to prepare hollow hydroxyapatite (HAP) microspheres with mespores on the surfaces is performed using a precipitation method assisted with Li2O-CaO-B2O3(LCB) glass fabrication process. This research is concerned with the effect of sintering temperature on the microstructure evolution, phase purity, surface morphology, specific surface area, and porosity after sintering process. The microspheres were sintered in air atmosphere at temperatures ranging from 500 to 900 °C. The starting hollow HAP microspheres and the sintered specimens were characterized by scanning electron microscope, X-ray diffractometer, specific surface area analyzer, and Hg porosimetry, respectively. The as-prepared microspheres consisted of calcium deficient hydroxyapatite. The results showed that the as-prepared hollow HAP microspheres had the highest specific surface areas, and the biggest total pore volume. The pore size distribution of the as-prepared hollow HAP microspheres were mainly the mesopores in the range of 2～40 nm. The specific surface area and total pore volume of hollow HAP microspheres decreased with increasing sintering temperature. Whereas the mean pore size increased with increasing sintering temperature. It showed that at 700°C, Ca-dHAP decomposes into a biphasic mixture of HAP and β-calcium phosphate(TCP).

scholarly journals The influence factors for gas adsorption with different ranks of coals

2017 ◽  
Vol 36 (3-4) ◽  
pp. 904-918 ◽  
Author(s):  
Deyong Guo ◽  
Xiaojie Guo
Keyword(s):  
Moisture Content ◽  
Specific Surface ◽  
Pore Structure ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Gas Adsorption ◽  
Total Pore Volume ◽  
Factors Influencing

In this paper, scanning electron microscopy, low-temperature N2 adsorption and CH4 isothermal adsorption experiments were performed on 11 coal samples with Ro,max between 0.98 and 3.07%. The pore structure characteristics of coals (specific surface area, total volume distribution) were studied to assess the gas adsorption capacity. The results indicate that there is significant heterogeneity on coal surface, containing numerous channel-like pores, bottle-shaped pores and wedge-shaped pores. Both Langmuir volume (VL) and Langmuir pressure (PL) show a stage change trend with the increase of coalification degree. For different coalification stages, there exist different factors influencing the VL and PL values. For low-rank coals (Ro,max < 1.1%), the increase of VL values and decrease of PL values are mainly due to the abundant primary pore and fracture within coal. For middle-rank coals (1.1% < Ro,max < 2.1%), the moisture content, vitrinite content and total pore volume are all the factors influencing VL, and the reduction of PL is mainly attributed to the decrease of moisture content and inertinite content. Meanwhile, this result is also closely related to the pore shape. For high-rank coals (Ro,max > 2.1%), VL values gradually increase and reach the maximum. When the coal has evolved into anthracite, liquid hydrocarbon within pore begins pyrolysis and gradually disappears, and a large number of macropores are converted into micropores, leading to the increase of specific surface area and total pore volume, corresponding to the increase of VL. In addition, the increase of vitrinite content within coal also contributes to the increase of VL. PL, reaches the minimum, indicating that the adsorption rate reaches the largest at the low pressure stage. The result is mainly controlled by the specific surface area and total pore volume of coal samples. This research results will provide a clearer insight into the relationship between adsorption parameters and coal rank, moisture content, maceral composition and pore structure, and it is of great significance for better assessing the gas adsorption capacity.

scholarly journals A large-surface-area TS-1 nanocatalyst: a combination of nanoscale particle sizes and hierarchical micro/mesoporous structures

RSC Advances ◽  
2019 ◽  
Vol 9 (17) ◽  
pp. 9694-9699 ◽  
Author(s):  
Changlin Du ◽  
Nan Cui ◽  
Linghao Li ◽  
Zile Hua ◽  
Jianlin Shi
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Total Pore Volume ◽  
High Specific Surface Area ◽  
Particle Sizes ◽  
Top Down ◽  
First Time ◽  
Mesoporous Structures

By dry-gel steam-assisted crystallization and top-down alkali-etching treatment, hierarchically structured TS-1 nanozeolites with abundant micro/mesopores were synthesized for the first time, with high specific surface area of 606 m2 g−1 and total pore volume of 0.86 cm3 g−1.

Optimization of Experimental Conditions for the Preparation of High Specific Surface Area Bamboo-Based Activated Carbon

2015 ◽  
Vol 1090 ◽  
pp. 154-159
Author(s):  
Sheng Zhou Zhang ◽  
Hong Ying Xia ◽  
Li Bo Zhang ◽  
Jin Hui Peng ◽  
Jian Wu ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Total Pore Volume ◽  
High Specific Surface Area ◽  
Raw Material ◽  
Experimental Conditions ◽  
Average Pore

Bamboo as the raw material is carbonized to prepare high specific surface area activated carbon by microwave heating under nitrogen atmosphere in our present work. Influences of activation agents on the preparation of activated carbon are studied. The results show that activation agents have a significant influence on the preparation of activated carbon. Under the heating time of 15 min, the adsorption capacity of the activated carbon prepared utilizing KOH as activation agent is the best. When the KOH/C ratio is 4, the iodine number and yield of activated carbon are 2298 mg/g and 39.82%, respectively. The BET specific surface area, total pore volume and average pore diameter of activated carbon are 3441 m2/g, 2.093 ml/g and 2.434 nm, respectively. The micropore volume of 1.304 ml/g is 62.30% of total pore volume, indicating that the activated carbon is microporous activated carbon.

scholarly journals Synthesis of micro-mesopores flowerlike γ-Al2O3 nano-architectures

2014 ◽  
Vol 79 (8) ◽  
pp. 1007-1017 ◽  
Author(s):  
Mozaffar Abdollahifar ◽  
Reza Zamani ◽  
Ehsan Beiygie ◽  
Hosain Nekouei
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Total Pore Volume ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
X Ray ◽  
Adsorption Desorption

The micro-mesopores flowerlike ?-Al2O3 nano-architectures have been synthesized by thermal decomposition method using the synthesized AlOOH (boehmite) as precursor. After calcination at 500?C for 5 h, the obtained flowerlike ?-Al2O3 has similar structure like the AlOOH precursor. X-ray diffraction (XRD), FTIR, TG, FESEM and TEM techniques were used to characterize morphology and structure of the synthesized samples. The specific surface area (BET), pore volume and pore-size distribution of the products were determined by N2 adsorption-desorption measurements. The flowerlike ?-Al2O3 showed BET high specific surface area 148 m2 g-1 with total pore volume 0.59 cm3 g-1.

Sign in / Sign up

Export Citation Format

Share Document