Effect of nitric acid on the pore structure and fractal characteristics of coal based on the low-temperature nitrogen adsorption method

2020 ◽  
Vol 367 ◽  
pp. 506-516 ◽  
Author(s):  
Guanhua Ni ◽  
Shang Li ◽  
Sheik Rahman ◽  
Meng Xun ◽  
Hui Wang ◽  
...  
Keyword(s):  
Nitric Acid ◽  
Low Temperature ◽  
Pore Structure ◽  
Nitrogen Adsorption ◽  
Adsorption Method ◽  
Fractal Characteristics

Research on Fractal Characteristics of Cement-Based Materials by Nitrogen Adsorption Method

2011 ◽  
Vol 415-417 ◽  
pp. 1545-1552 ◽  
Author(s):  
Ming Tang ◽  
Jing Qi Li
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Surface Characteristics ◽  
Adsorption Method ◽  
Surface Fractal Dimension ◽  
Surface Fractal ◽  
Cement Based Materials ◽  
Fractal Characteristics

In order to confirm the surface fractal dimension of the internal pore of complex porous materials by means of the FHH model and nitrogen adsorption method. Study the change rule on fractal characteristics of the pore of cement based materials further. The results shows that, surface area of the complex internal structure of cement based materials has the fractal characteristics observably. Testing and evaluating the fractal characteristics on surface area of the pore of cement-based materials is effective by nitrogen adsorption method. It is good for analyzing surface characteristics of pore structure further. Surface fractal dimension of pore structure and surface area have not good correlation. The characteristics and conclusion that quality fractal dimension of powder and surface area evaluating fineness of powder have not very good correlation is consistent.

Variation in Pore Structure Characteristics with Composition in the High Volatile Bituminous Coal of Binchang Area

2014 ◽  
Vol 962-965 ◽  
pp. 890-898
Author(s):  
Jin Ping Li ◽  
Da Zhen Tang ◽  
Ting Xu Yu ◽  
Gang Sun
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Parallel Plate ◽  
Bituminous Coal ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Test Results ◽  
Structure Characteristics ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Pore structure characteristics and the effect of lithotype and maceral on pore for three types of high-volatile bituminous coals from Binchang area were investigated by combined low-temperature nitrogen adsorption/desorption, nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and maceral analysis. The low temperature N2 adsorption/desorption test results show that: micropores are more abundant than transitional pores with high BET surface area; two types of pore structures can be identified by adsorption/desorption isotherms; Pore morphology is mainly represented by well-connected, ink-bottled, cylindrical and parallel plate pores. NMR T2 distributions at full saturated condition are apparent or less obvious trimodal and three types of T2 distributions are identified; Seepage pores are better developed when compared with the middle-high rank coal. Further research found that the three coal lithotypes are featured by remarkably different pore structure characteristics and maceral contents of coal are linearly correlated to some of pore structure parameters.

scholarly journals An Investigation of Fractal Characteristics of Marine Shales in the Southern China from Nitrogen Adsorption Data

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Jian Xiong ◽  
Xiangjun Liu ◽  
Lixi Liang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Southern China ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Mean Value ◽  
Relative Pressure ◽  
Pore Surface ◽  
Adsorption Sites ◽  
Fractal Characteristics

We mainly focus on the Permian, Lower Cambrian, Lower Silurian, and Upper Ordovician Formation; the fractal dimensions of marine shales in southern China were calculated using the FHH fractal model based on the low-pressure nitrogen adsorption analysis. The results show that the marine shales in southern China have the dual fractal characteristics. The fractal dimensionD1at low relative pressure represents the pore surface fractal characteristics, whereas the fractal dimensionD2at higher relative pressure describes the pore structure fractal characteristics. The fractal dimensionsD1range from 2.0918 to 2.718 with a mean value of 2.4762, and the fractal dimensionsD2range from 2.5842 to 2.9399 with a mean value of 2.8015. There are positive relationships between fractal dimensionD1and specific surface area and total pore volume, whereas the fractal dimensionsD2have negative correlation with average pore size. The larger the value of the fractal dimensionD1is, the rougher the pore surface is, which could provide more adsorption sites, leading to higher adsorption capacity for gas. The larger the value of the fractal dimensionD2is, the more complicated the pore structure is, resulting in the lower flow capacity for gas.

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 Nanoscale pore characteristics and fractal characteristics of organic-rich shale: An example from the lower Cambrian Niutitang Formation in the Fenggang block in northern Guizhou Province, South China

2018 ◽  
Vol 37 (1) ◽  
pp. 273-295 ◽  
Author(s):  
Yang Gu ◽  
Wenlong Ding ◽  
Min Yin ◽  
Baocheng Jiao ◽  
Siyu Shi ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Pore Structure ◽  
Carbon Content ◽  
South China ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Organic Carbon Content ◽  
Structure Parameters ◽  
Pore Characteristics ◽  
Fractal Characteristics

Organic-rich marine shale in South China has great potential for gas generation, and the pore structure has a considerable influence on the enrichment of shale gas. The nanoscale pore characteristics and fractal characteristics of the Niutitang shales in the Fenggang block were studied by means of methane adsorption and low-pressure nitrogen adsorption experiments, porosity and permeability tests, X-ray diffraction analyses, organic geochemical analyses, and field emission scanning electron microscopy. The fractal geometry of the pore structure was assessed, and the factors influencing the pore structure were determined. We used a fractal Frenkel–Halsey–Hill-based method to obtain the fractal dimensions D1 and D2 by nitrogen adsorption at relative pressures of 0–0.5 and 0.5–1, respectively. The relationships between the shale pore structure parameters and the fractal dimensions, the mineral composition, the total organic carbon content, and the pore structure parameters of shale are discussed. In addition, the significance of D1 and D2 and the implications of the fractal dimension for the adsorption capacity of shale are investigated. The results show that the two fractal dimensions are positively correlated with total organic carbon content and specific surface area, negatively correlated with quartz content and average pore diameter, but have a weak relationship with clay mineral content and total pore volume. The Niutitang shale samples are dominated by mesopores, and the pore structure is complicated. The results presented here indicate that fractal analyses represent an effective method of characterizing the complexity of pore structure.

scholarly journals Fractal characteristics and significances of the nanopores in oil shales during hydrous pyrolysis

2019 ◽  
Vol 10 (2) ◽  
pp. 557-567
Author(s):  
Lina Sun ◽  
Deliang Fu ◽  
Shunqi Chai ◽  
Wenxia Yang ◽  
Kai Zhou ◽  
...  
Keyword(s):  
Gas Adsorption ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
Relative Pressure ◽  
Thermal Maturity ◽  
Adsorption Method ◽  
Pore Structures ◽  
Hydrous Pyrolysis ◽  
Fractal Characteristics

Abstract In order to explore the pore characterizations in shales during organic matter evolution, a series of simulation experiments were conducted. The artificial hydrous pyrolysis was conducted on the same seven columned oil-shale samples at 250 °C, 300 °C, 350 °C, 375 °C, 400 °C, 450 °C and 500 °C, respectively. To obtain the characteristics of pore structures in shales, the unheated and the residual solid samples were analyzed by low-pressure nitrogen adsorption method. Based on the nitrogen adsorption isotherms, fractal dimensions were calculated by the model of Frenkel–Halsey–Hill, which also contained the fractal dimension of D1 and D2 before and after the relative pressure P/Po = 0.5, respectively. And then the relationships of simulation temperatures (thermal maturity), total-, macro-, meso- and micro-pores volumes, specific surface areas and diameters to fractal dimensions were investigated. The results showed that the average value of D2 (2.6110) was higher than D1 (2.4147) and there was a positive relationship between them (R2 = 0.9237), which indicated that though D2 and D1 were more related to pore structures and surfaces, the better linear relationships suggested that both of them could be used in the representation of pore structures and surfaces in shales. With the thermal maturity increasing, the obvious fractal characteristics were, the complexity of pore structures were, which may be associated with the following cause-and-effect relationships. During the pyrolysis, the generation of hydrocarbons increased, as well as the consumption of TOC may increase the volume and surface area of total-, macro-, meso- and micro-pores but decrease the corresponding average diameter and then the quantities of smaller pores occurred and led to the strengthening of pore heterogeneity in shales. Based on the fractal characteristics, we also found the higher thermal maturity would result in the better connections among pores but worse permeability in shale, which further increased the gas adsorption quantity. Therefore, analyzing the fractal characteristics in shales could provide help for clarifying the characteristics of reservoirs as well as the comprehensive exploration and development of shale gas.

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