Adsorption and diffusion of moisture and wet flue gas on silica gel

Biomass/Biochar carbon materials for CO2 capture and sequestration by cyclic adsorption processes: A review and prospects for future directions

“…Water vapor is one of the undesired components in the gas mixture, which has adverse effect on the loading capacity of sorbents especially MOFs, Zeolites, etc. [178][179][180]. To this end, recently, several ACs originated from agricultural wastes have been considered to study water vapor effects on the separation and purifications processes including natural gas sweeting, biogas upgrading, air drying, and post-combustion processes [181][182][183].…”

Binary- and Pure-Component Adsorption of CO2, H2O, and C6H14 on SSZ-13

“…Measurement of binary and more complex mixtures for adsorption often requires construction of custom-built adsorption systems. Examples of these systems include volumetric adsorption with recycle pumps and specialized gas detection equipment, zero-length columns with mass spectrometers, gravimetric systems with multiple mass flow controllers and gas detection equipment, and dynamic breakthrough column systems with measurement of the gas-phase effluent. ,,− For applications where CO 2 may be affected by coadsorption of other strongly adsorbing components, a simpler methodology may be of interest for assessing potential of many CO 2 -selective materials for adsorption and other separations.…”

Direct measurement of the mass transport coefficient of water in silica-gel using the zero length column technique

“…The most important assumption that is made is that the system remains isothermal, which is typically the case in a ZLC system [18] for 2 reasons: the first is due to the fact that a very small sample is housed in contact with a large mass of steel; the second is that all of the gas flows through the column providing additional convective heat transfer, thus limiting the temperature rise in adsorption and the temperature drop in desorption. A check of the worst case scenario can be carried out to estimate the maximum temperature rise estimating the Nusselt number for an isolated sphere using literature values of the heat capacity [13,25] and the energy of adsorption [13]. Experimentally a simple check is through a change in carrier gas, which will vary the heat transfer coefficient.…”

“…Very similar mass transfer coefficients for water on silica-gel using large concentration swings that include the hysteresis loop have been used in the simulation of air drying using pressure swing adsorption [26,27]. A recent study based on modelling breakthrough curves [13] gives lower values by a factor of approximately 5, but still of a similar order of magnitude.…”

“…Volumetric and gravimetric commercial systems are available to determine individual points on isotherms and are time consuming experiments [8][9][10][11][12]. Mass transfer coefficients are then measured using a variety of techniques which require combined heat and mass transfer models [13][14][15][16], in addition to a suitable form of isotherm model which has to also capture accurately the adsorption energy, as the experiments are performed under non-isothermal conditions. With mesoporous materials such as silica-gel there is also the added complication that the isotherm exhibits a hysteresis loop leading to difficulties in representing correctly adsorption and desorption kinetics.…”