Adsorption model coals

Pan Z. and ConnelL.D. A theoretical model for gas adsorption-induced coal swelling. 2007 International Journal of Coal Geology 69(4) 243-252. 

For the evaluation of different adsorbents, the first measure is to determine adsorption isotherms that show the capacity of the coal for the target compound versus equilibrium concentration. These adsorption isotherms can be characterized by different adsorption models. 

The extended Langmuir model (ELM) is the most common approach used to represent multicomponent gas adsorption in coal. This is based on direct extension of the single component isotherm to a multicomponent system giving the analogous expression... 

The natural gas consists mainly of methane, and the adsorption of methane on coals and activated carbons has been studied by a number of workers. The adsorption on coal has generally been found to be physical as indicated by small heats of adsorption and the reversibility of the adsorption isotherms. The adsorption at the ambient temperature takes place in the micropores. Ruppel et al. studied the adsorption of methane on coals at temperatures of 0 to 50°C and at pressures from 1 to 15 mPa, and applied Langmuir and Polanyi adsorption models. Ruppel found that the adsorption could be well explained by the Langmuir equation. 

Using coal-based sorbents, Sivasamy et al. [62] evaluated their ability to remove fluoride from water. On equilibrium basis, Langmuir and Freundlich models were used to describe the data points, while the kinetic data points were interpreted in terms of reaction and mass transfer processes. Kaolinite, adioctahedral two-layered (silica and alumina) silicate (1 2 type), has also been tested in drinking water defluoridation. Recently, Sugita etal. [58] and earlier Kau etal. [63] and Weerasooriya et al. [10] presented fluoride adsorption results of kaolinite. The fluoride-binding sites in kaolinite consist of aluminol and silinol sites. The authors explained that the fluoride-kaolinite interaction led to the formations of both the inner- and outer-sphere complexes. 

Ozdemir, E. (2004) Ph.D. thesis Chemistry of the adsorption of carbon dioxide by argorme premium coals and a model to simulate CO2 sequestration in coal seams. University of Pittsburg, Pittsburgh. 

Type of Reaction and Application. An increased emphasis on gas-solid reactions has been evident for about a decade. Three of the papers in this symposium treat gas-solid reactions, two (13,18) dealing with coal combustion and the other (11) with catalyst regeneration. Of the four papers which consider solid-catalysed gas-phase reactions, one (15) deals with a specific application (production of maleic anhydride), and one (12) treats an unspecified consecutive reaction of the type A B C the other two (14,16) are concerned with unspecified first order irreversible reactions. The final paper (17) considers a relatively recent application, fluidized bed aerosol filtration. Principles of fluid bed reactor modeling are directly applicable to such a case Aerosol particles disappear by adsorption on the collector (fluidized) particles much as a gaseous component disappears by reaction in the case of a solid-catalysed reaction. 

In evaluating the mechanistic models for sorption by coals, one is well advised to consider the contrast of the two general classes of sorbents physical adsorption (sometimes called physisorption) will likely alter the surface structure of a molecular solid adsorbent (such as ice, paraffin, and polymers), but not that of high surface energy, refractory solids (such as the usual metals and metal oxides, and carbon black) (9). Adamson (27) has proposed... 

Numerical modelling of outbursts requires the quantification of a number of processes and factors. These include gas adsorption and desorption, coal deformation and failure, coal fragmentation, gas dynamics and transport of outburst coal (particle flow). 

ABSTRACT In order to investigate the effect of coal particle size on gas desorption and diffusion law at constant temperature, the constant temperature dynamic coal particle gas adsorption and desorption experiment with different particle sizes was conducted in the coal gas adsorption and desorption experiment system. The results suggest that gas desorption laws of different particle size of coal samples show a good consistency at different pressures, and the cumulative desorption of gas coal particle is linear with time. For the same particle, the higher the initial pressure, the more the maximum gas desorption the smaller the coal particle is, the more quickly the gas desorption rate is at the same initial pressure. Then, the gas spherical flow mathematical model is built based on Darcy law and is analysed with finite difference method. At last, the gas spherical flow mathematical model is constructed with Visual Basic. The contrast between numerical simulation and experimental results shows that the gas flow in the coal particle internal micropore accords with Darcy s law. 

I. Gas cylinder 2. Gas adsorption chamber 3. Outburst hole and rubber membrane 4. Pressure sensor 5. Speed sensor 6. Model of roadway 7. High-speed camera. 8. Personal computer 9. Small coal "sotting" acquisition board... 

The fractal approach was also used to investigate adsorption and desorption mechanisms of water vapor on active carbons that were derived from coconut shell, coal, coke and pitch fiber featuring a wide range of BET specific surface areas [78]. A values were measured for the water clusters adsorbed on primary carbon centers. Values ranging from 1.64 to 1.67 implied a diffusion-limited aggregation model on a pore wall plane, whereas higher A values (up to 1.86), measured at a relative pressure X = 0.95, implied the formation of water clusters that were partly merged vertically to the walls. 

---