scholarly journals On the high density hydrogen films adsorbed in carbon nanospaces

2015 ◽  
Author(s):  
◽  
Elmar Dohnke
Keyword(s):  
High Pressure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Isosteric Heat ◽  
New Method ◽  
Cryogenic Temperatures ◽  
Adsorbed Film ◽  
Surface Areas ◽  
Bet Theory

The commercialization of hydrogen-powered fuel cell cars, with their environmentally friendly emissions, provides an opportunity to replace current gasoline powered vehicles. The main drawback of hydrogen as a fuel is the low density at ambient temperatures. The gas needs to be compressed to high pressure or kept under cryogenic temperatures to achieve reasonably long driving ranges. These obstacles can be overcome if the tanks are filled with a porous material that adsorbs a high volume of hydrogen. Many materials are put forward for this purpose, such as metal organic frameworks (MOFs) and engineered carbon nanospaces (synthetic carbon). To get a better understanding of the materials performance, an attempt was made to analyze the properties of the adsorbed hydrogen film. High pressure hydrogen isotherms at cryogenic temperatures (77 K, 50 K) have been studied to estimate adsorbed film properties such as density and thickness. Furthermore, how isosteric heat of adsorption, surface chemistry, and pore size distribution affect the adsorbed film has been investigated. At supercritical temperatures and high pressures, a film density 20% higher than liquid hydrogen at 1 bar and 20 K was obtained. These densities are independent of the isosteric heat of adsorption or pore size distribution. The adsorbed film densities behave similarly for all carbon-based surfaces at 77 K. Additionally a new method was developed to estimate specific surface areas of gas storage materials from high pressure isotherms and tested against the BET theory. The new method does not require knowledge of the packing fraction or cross-sectional area of an adsorbed molecule in the film. In most cases the new method leads to surface areas comparable to those found using BET theory if cryogenic high pressure isotherms are used. A new manometric (Sieverts type) adsorption instrument was designed and test, capable of measuring sub- and supercritical hydrogen isotherms at high pressure.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

Positronium Thermalization Process in Nanoporous Materials and its Influence on the Shape of PALS Spectrum

2008 ◽  
Vol 607 ◽  
pp. 39-41
Author(s):  
Jerzy Kansy ◽  
Radosław Zaleski
Keyword(s):  
Mesoporous Silica ◽  
Pore Size Distribution ◽  
Porous Materials ◽  
Pore Size ◽  
Size Distribution ◽  
Nanoporous Materials ◽  
New Method ◽  
New Model ◽  
Conventional Models ◽  
Mcm 41

A new method of analysis of PALS spectra of porous materials is proposed. The model considers both the thermalization process of positronium inside the pores and the pore size distribution. The new model is fitted to spectra of mesoporous silica MCM-41 and MSF. The resulting parameters are compared with parameters obtained from fitting the “conventional” models, i.e. a sum of exponential components with discrete or/and distributed lifetimes.

pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

2019 ◽  
Author(s):  
Paul Iacomi ◽  
Philip L. Llewellyn
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Isosteric Heat ◽  
Material Characterisation ◽  
Mixture Adsorption ◽  
Surface Energetics ◽  
Adsorption Processing ◽  
User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

scholarly journals Adamantane-Based Micro- and Ultra-Microporous Frameworks for Efficient Small Gas and Toxic Organic Vapor Adsorption

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 486 ◽  
Author(s):  
Wenzhao Jiang ◽  
Hangbo Yue ◽  
Peter Shuttleworth ◽  
Pengbo Xie ◽  
Shanji Li ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Bet Surface Area ◽  
Organic Vapors ◽  
Practical Applications ◽  
Organic Vapor ◽  
Surface Areas ◽  
Wide Range ◽  
Microporous Organic Polymers

Microporous organic polymers and related porous materials have been applied in a wide range of practical applications such as adsorption, catalysis, adsorption, and sensing fields. However, some limitations, like wide pore size distribution, may limit their further applications, especially for adsorption. Here, micro- and ultra-microporous frameworks (HBPBA-D and TBBPA-D) were designed and synthesized via Sonogashira–Hagihara coupling of six/eight-arm bromophenyl adamantane-based “knots” and alkynes-type “rod” monomers. The BET surface area and pore size distribution of these frameworks were in the region of 395–488 m2 g−1, 0.9–1.1 and 0.42 nm, respectively. The as-made prepared frameworks also showed good chemical ability and high thermal stability up to 350 °C, and at 800 °C only 30% mass loss was observed. Their adsorption capacities for small gas molecules such as CO2 and CH4 was 8.9–9.0 wt % and 1.43–1.63 wt % at 273 K/1 bar, and for the toxic organic vapors n-hexane and benzene, 104–172 mg g−1 and 144–272 mg g−1 at 298 K/0.8 bar, respectively. These are comparable to many porous polymers with higher BET specific surface areas or after functionalization. These properties make the resulting frameworks efficient absorbent alternatives for small gas or toxic vapor capture, especially in harsh environments.

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