scholarly journals Pore size distributions and pore multifractal characteristics of medium and low-rank coals

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bin Sun ◽  
Qing Yang ◽  
Jie Zhu ◽  
Tangsha Shao ◽  
Yuhang Yang ◽  
...  
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Nitrogen Adsorption ◽  
Low Rank ◽  
Size Distributions ◽  
Confining Stress ◽  
Mercury Intrusion ◽  
Pore Size Distributions ◽  
Porosity And Permeability ◽  
Low Rank Coals

AbstractIt is of great significance to study the porosity and permeability properties of medium and low-rank coal. The porosity and permeability in confining stress experiments were used to simulate the porosity and permeability variations of coal samples under different depth conditions. The pore structure of Baoqing coal samples is greatly affected by the confining pressure, and the pores and micro cracks are more easily compressed. Based on the experimental data of mercury intrusion porosimetry (MIP) and nitrogen adsorption (NA), the pore size distributions (PSDs) of medium and low-rank coals were studied. High mercury intrusion pressure would lead to coal matrix compression. Therefore, the pore volume calculated by MIP data was corrected by NA data. The PSDs characteristics of Jixi (JX) coal and Baoqing (BQ) coal samples are obtained from the revised pore volume, and the dominant pores of medium and low-rank coals are obtained. The results show that JX coal has higher spatial heterogeneity, connectivity and pore autocorrelation. Micro fractures have an influence on the autocorrelation and heterogeneity of coal samples, especially for BQ coal samples.

scholarly journals Surfactant-Free Solvothermal Method for Synthesis of Mesoporous Nanocrystalline TiO2Microspheres with Tailored Pore Size

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yajing Zhang ◽  
Sujuan Zhang ◽  
Kangjun Wang ◽  
Fu Ding ◽  
Jing Wu
Keyword(s):  
Pore Size ◽  
Anatase Phase ◽  
Nitrogen Adsorption ◽  
Ethanol Solution ◽  
Tetrabutyl Titanate ◽  
Size Distributions ◽  
Pore Size Distributions ◽  
Structure Morphology ◽  
Mesoporous Microspheres ◽  
Adsorption Desorption

TiO2mesoporous microspheres self-assembled from nanoparticles were synthesized by a surfactant-free solvothermal route. The TiO2precursors were fabricated by tetrabutyl titanate, glacial acetic acid, and urea in the ethanol solution at 140°C for 20 h, and TiO2mesoporous microspheres were obtained by a postcalcination at temperatures of 450°C for promoting TiO2crystallization and the removal of residual organics. The phase structure, morphology, and pore nature were characterized by XRD, SEM, and nitrogen adsorption-desorption measurements. The as-prepared TiO2microspheres are in anatase phase, with 2-3 μm in diameter, and narrow pore distribution range is 3-4 nm. The adjustments of the synthetic parameters lead to the formation of the mesoporous TiO2microspheres with tuned pore size distributions and morphology.

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content

1987 ◽  
Vol 4 (1-2) ◽  
pp. 87-104 ◽  
Author(s):  
Bruce D Adkins ◽  
Jill B. Heink ◽  
Burtron H. Davis
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Size Distributions ◽  
Electron Microscopic ◽  
Pore Size Distributions ◽  
Electron Microscopic Data ◽  
Penetration Data

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

Article

1998 ◽  
Vol 76 (4) ◽  
pp. 382-388 ◽  
Author(s):  
Jack M Miller ◽  
David Wails ◽  
J Stephen Hartman ◽  
Karla Schebesh ◽  
Jennifer L Belelie
Keyword(s):  
Catalytic Activity ◽  
Pore Size ◽  
Zinc Chloride ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Potassium Fluoride ◽  
Physical Structure ◽  
Alkylation Reaction ◽  
Size Distributions ◽  
Pore Size Distributions

Novel mesoporous silicas have been prepared via a sol-gel route involving fluoride-catalyzed hydrolysis of tetraethylorthosilicate (TEOS). Incorporation of zinc chloride by sol-gel synthesis gives a range of mesoporous materials with significantly higher catalytic activity than the commercially available catalyst, Clayzic, in a model Friedel-Crafts alkylation reaction. The dependence of catalytic activity and physical structure on the amounts of solvent, water, zinc chloride, and potassium fluoride used in the preparation are explored, and the materials have been further characterized by nitrogen adsorption to determine surface areas, total pore volumes, and pore-size distributions and by 29Si and 19F MAS NMR spectroscopy. The most active catalysts generally have the highest total pore volumes, with pore-size distributions larger than 8 nm.Key words: sol-gel, Friedel-Crafts, Clayzic, silica.

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