scholarly journals The dynamic change of pore structure for low-rank coal under refined upgrading pretreatment temperatures

2020 ◽  
Author(s):  
Teng Li ◽  
Cai-Fang Wu ◽  
Zi-Wei Wang
Keyword(s):  
Pore Structure ◽  
Pore Volume ◽  
Dynamic Change ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Volatile Matter ◽  
Low Rank ◽  
Low Rank Coal ◽  
Pore Collapse ◽  
Pretreatment Temperature

AbstractPore structure characteristics are significant factor in the evaluation of the physical characteristics of low-rank coal. In this study, three low-rank coal samples were collected from the Xishanyao Formation, Santanghu Basin, and low-temperature liquid-nitrogen adsorption (LP-N2A) measurements were taken under various pretreatment temperatures. Owing to the continuous loss of water and volatile matter in low-rank coal, the total pore volume assumes a three-step profile with knee temperatures of 150 °C and 240 °C. However, the ash in the coal can protect the coal skeleton. Pore collapse mainly occurs for mesopores with aperture smaller than 20 nm. Mesopores with apertures smaller than 5 nm exhibit a continuous decrease in pore volume, whereas the pore volume of mesopores with apertures ranging from 5 to 10 nm increases at lower pretreatment temperatures (<150 °C) followed by a faint decrease. As for mesopores with apertures larger than 10 nm, the pore volume increases significantly when the pretreatment temperature reaches 300 °C. The pore structure of low-rank coal features a significant heating effect, the pretreatment temperature should not exceed 150 °C when the LP-N2A is used to evaluate the pore structure of low-rank coal to effectively evaluate the reservoir characteristics of low-rank coal.

scholarly journals Multi-fractal characteristics of pore structure for coal during the refined upgrading degassing temperatures

2021 ◽  
Author(s):  
Jianjun Wang ◽  
Lingli Liu ◽  
Zehong Cui ◽  
Hongjun Wang ◽  
Teng Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Fractal Theory ◽  
Dynamic Change ◽  
Ordos Basin ◽  
Nitrogen Adsorption ◽  
Low Rank ◽  
Low Rank Coal ◽  
Adsorption Measurement ◽  
Fractal Spectrum

AbstractThe low-temperature nitrogen adsorption measurement is commonly used to describe the pore structure of porous medium, while the role of degassing temperature in the low-temperature nitrogen adsorption measurement does not attract enough attention, various degassing temperatures may lead to the different pore structure characterization for the same coal. In this study, the low-rank coal collected from Binchang mining area, southwest of Ordos Basin was launched the low-temperature nitrogen adsorption measurement under seven various degassing temperatures (120 °C, 150 °C, 180 °C, 210 °C, 240 °C, 270 °C and 300 °C), respectively, the dynamic change of the pore structure under refined upgrading degassing temperatures are studied, and it was also quantitative evaluated with the multi-fractal theory. The results show that the pore specific surface area and pore volume decrease linearly with the increased degassing temperatures, ranges from 12.53 to 2.16 m2/g and 0.01539 to 0.00535 cm3/g, respectively. While the average pore aperture features the contrary characteristics (various from 4.9151 to 9.9159 nm), indicating the pore structure has been changed during the refined upgrading degassing temperatures. With the upgrading degassing temperatures, the sizes of hysteresis loop decrease, and the connectivity of pore structure enhanced. The multi-fractal dimension and multi-fractal spectrum could better present the partial abnormal of pore structure during the refined upgrading degassing temperatures, and the quality index, Dq spectrum, D−10–D10 and multi-fractal spectrum could describe the homogeneity and connectivity of the pores finely. The degassing temperatures of 150 °C, 180 °C and 270 °C are selected as three knee points, which can reflect the partial abnormal of the pore structure during the refined upgrading degassing temperatures. Under the lower degassing temperature (< 150 °C), the homogeneity and connectivity of the pore feature a certain increase, following that it presents stable when the degassing temperatures various from 150 to 180 °C. The homogeneity and connectivity of the pore would further enhanced until the degassing temperature reaches to 270 °C. Because of the melting of the pore when the degassing temperature exceeds 270 °C, the complexity of pore structure increased. In this study, we advise the degassing temperature for low-temperature nitrogen adsorption measurement of low-rank coal should not exceed 120 °C.

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.

Experimental Study on Coal Pore Characteristic Based on Cryogenic Liquid Nitrogen Method

2013 ◽  
Vol 341-342 ◽  
pp. 345-350 ◽  
Author(s):  
Wei Min Cheng ◽  
Xiao Qiang Zhang ◽  
Rui Zhang ◽  
Gang Wang
Keyword(s):  
Pore Structure ◽  
Surface Area ◽  
Liquid Nitrogen ◽  
Pore Volume ◽  
Single Point ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Cryogenic Liquid ◽  
Adsorption Method ◽  
Point Total

In view of pore distribution in coal, this paper applies BJH method that is based on the cylinder theory and adopts cryogenic liquid nitrogen adsorption method to carry out experimental investigation on pore structure of No.3U coal seam in Sanhekou Coalmine, obtaining the fact that pore structure of No.3U coal is complicated, the cool pores are mostly flask pores, others are the parallel plate pores with one end closed and the cylinder pores with one end closed; According to the distribution of BJH pore volume and pore surface area, ultramicropores with apertures less than 10 nm are among the most; Then obtain the average BET specific surface area, the distribution of BJH pore volume and pore area, average single-point total pore volume and most probable pore .etc, which conducive to a better understanding of the micropores characteristic of coal.

scholarly journals Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2879 ◽  
Author(s):  
Yuming Liu ◽  
Bo Shen ◽  
Zhiqiang Yang ◽  
Peiqiang Zhao
Keyword(s):  
Pore Structure ◽  
Oil And Gas ◽  
Vitrinite Reflectance ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Controlling Factors ◽  
Structure Characterization ◽  
Bakken Formation ◽  
Main Controlling Factors ◽  
Bakken Shale

The Bakken Formation is a typical tight oil reservoir and oil production formation in the world. Pore structure is one of the key factors that determine the accumulation and production of the hydrocarbon. In order to study the pore structures and main controlling factors of the Bakken Formation, 12 samples were selected from the Bakken Formation and conducted on a set of experiments including X-ray diffraction mineral analysis (XRD), total organic carbon (TOC), vitrinite reflectance (Ro), and low-temperature nitrogen adsorption experiments. Results showed that the average TOC and Ro of Upper and Lower Bakken shale is 10.72 wt% and 0.86%, respectively. The Bakken Formation develops micropores, mesopores, and macropores. However, the Upper and Lower Bakken shale are dominated by micropores, while the Middle Bakken tight reservoir is dominated by mesopores. The total pore volume and specific surface area of the Middle Bakken are significantly higher than those of the Upper and Lower Bakken, indicating that Middle Bakken is more conducive to the storage of oil and gas. Through analysis, the main controlling factors for the pore structure of the Upper and Lower Bakken shale are TOC and maturity, while those for Middle Bakken are clay and quartz contents.

Effect of valence of copper on adsorption of dimethyl sulfide from liquid hydrocarbon streams on activated bentonite

2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Huan Huang ◽  
De-Zhi Yi ◽  
Yan-Nan Lu ◽  
Xiao-Lin Wu ◽  
Yun-Peng Bai ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Pore Volume ◽  
Dimethyl Sulfide ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Copper Cation ◽  
Liquid Hydrocarbon ◽  
Activated Bentonite ◽  
Better Than

AbstractSamples of activated bentonite and activated bentonite modified with CuCl and CuCl2, separately, were tested as dimethyl sulfide (DMS) adsorbents. The adsorption and desorption behaviours of DMS on the adsorbents were studied systematically. The adsorbents were characterised by nitrogen adsorption, XRD, and DMS-TPD tests. The addition of CuCl and CuCl2 to the activated carbon significantly enhanced the adsorption capacity of DMS, despite a notable decrease in the specific surface area and total pore volume of the activated bentonite. It is presumed that copper cation species may act as an adsorption site for DMS. The adsorption capacity of Cu(II)-bentonite was better than that of Cu(I)-bentonite. The DMS-TPD patterns indicate that the stronger electrophilicity of Cu(II) compared to that of Cu(I) caused it to interact with the DMS molecules more strongly, thus contributing to a better adsorptive performance. The Cu(II)-bentonite calcined at 150°C had the best DMS removal performance with a high sulphur capacity of 70.56 mg S g−1 adsorbent. The DMS removal performance became much lower with the increase in the calcination temperature, which appeared to be due to the decrease in the CuCl2·2H2O phase and the formation of the monoclinic Cu(OH)Cl phase.

scholarly journals Characteristics of low-rank and medium-rank Indonesian coal using the TG-DSC method

2021 ◽  
Vol 882 (1) ◽  
pp. 012031
Author(s):  
Hariana ◽  
A Prismantoko ◽  
H P Putra ◽  
A P Nuryadi ◽  
Sugiarto ◽  
...  
Keyword(s):  
Moisture Content ◽  
Power Plants ◽  
Decisive Role ◽  
Volatile Matter ◽  
Low Rank ◽  
Low Rank Coal ◽  
Heating Value ◽  
Burning Coal ◽  
Indonesian Coal ◽  
Lower Temperature

Abstract Low-rank and medium-rank coal are dominant coal resources in Indonesia. Considering the decisive role of coal in coal-fired power plants, it is crucial to examine the combustion characteristics before burning coal in the boiler. This paper presents the effect of moisture content, heating value, and volatile matter on ignition temperature and burn out of five samples of low-rank coal and five samples of medium-rank coal using TG-DSC analysis which was carried out using LINSEIS High-Pressure STA at atmospheric pressure with an air rate of 25 ml/min and heating rate of 10 °C/min. The investigation results show that low-rank coal with the higher volatile matter has tremendous reactivity and is more flammable, and favours of burning through itself than medium-rank coal. Medium-rank coal has better combustion with short residence time because it has a lower burnout temperature (Tbo) value than low-rank coal. However, medium-rank coal burns more instantly because it has a lower temperature interval than low-rank coal. Medium-rank coal, which has fixed carbon and higher heating value, but lower moisture content, has a higher Rmax value than low-rank coal. In conjunction with these properties, it is crucial to examine the implementation in boilers.

scholarly journals Characterization of Metal-Impregnated Charcoal: Nitrogen Adsorption

1995 ◽  
Vol 12 (2) ◽  
pp. 101-107 ◽  
Author(s):  
Riaz Qadeer ◽  
Javed Hanif ◽  
Abdul Majeed
Keyword(s):  
Surface Area ◽  
Pore Volume ◽  
Continuous Flow ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Ionic Radii ◽  
Sorption System ◽  
Metal Impregnation ◽  
Continuous Flow Method

Nitrogen adsorption on metal (Ni, Cu, Zn) impregnated charcoal has been carried out at 77 K by the continuous flow method using a Quantasorb sorption system. It was observed that such metal impregnation did not contribute any extra surface area to the charcoal. The values of the surface area, micropore and total pore volumes determined from nitrogen adsorption follow the sequence Ni–charcoal < Cu–charcoal < Zn–charcoal < charcoal. Their behaviour is discussed in terms of the ionic radii of the metal ions concerned. The pore size distribution curves demonstrate the microporous nature of the charcoal, with the micropores contributing significantly to the total pore volume.

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.

Effect of Heat-Treatment in Ar Atmosphere on Pore Structure of Carbonaceous Materials from Polysiloxane

2014 ◽  
Vol 602-603 ◽  
pp. 279-284
Author(s):  
Li Qun Duan ◽  
Chen Chen Zhang ◽  
Qing Song Ma ◽  
Zhao Hui Chen
Keyword(s):  
Heat Treatment ◽  
Pore Structure ◽  
Pore Size ◽  
Pore Volume ◽  
Average Pore Size ◽  
Total Pore Volume ◽  
Treatment Temperature ◽  
Carbonaceous Materials ◽  
Average Pore ◽  
Pore Size Distributions

Nanoporous carbonaceous materials derived from polysiloxane were first prepared by pyrolysis at 1300°C followed with hydrofluoric acid (HF) etching treatment. Their thermal stability of pore structure in inert condition was investigated in this paper by nitrogen adsorption technique in detail. The specific surface area (SSA) and pore volume (total pore volume, micropore volume, mesopore volume) decreased continually in the heat-treatment temperature range of 1000~1400°C. The average pore size almost kept the same with the raw sample. However, when the temperature exceeded 1400°C, the micropore interconnection began transforming to mesopore structure, which led to the decline of SSA and the increase of average pore size. Furthermore, the pore size distributions (PSDs) curves showed that heat-treatment had an advantage on the transition process of pore structure from disorder to regularity to some extent when heat-treated in the range 1000~1400°C for the most possible reason of relief of residue strain in the carbonaceous materials.

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