Enzo Mangano

Net, excess and absolute adsorption and adsorption of helium

The definitions of absolute, excess and net adsorption in microporous materials are used to identify the correct limits at zero and infinite pressure. Absolute adsorption is shown to be the fundamental thermodynamic property and methods to determine the solid density that includes the micropore volume are discussed. A simple means to define when it is necessary to distinguish between the three definitions at low pressure is presented. To highlight the practical implications of the analysis the case of adsorption of helium is considered in detail and a combination of experiments and molecular simulations is used to clarify how to interpret adsorption measurements for weakly adsorbed components.

Accelerated degradation of MOFs under flue gas conditions

The zero length column (ZLC) technique is used to investigate the stability of Mg- and Ni-CPO-27 metal-organic framework (MOF) crystals in the presence of water and humid flue gas. The design of the ZLC enables the stability test to be conducted over a considerably shorter time period and with lower gas consumption than other conventional techniques. A key advantage over other experimental methods for testing the stability of adsorbents is the fact that the ZLC allows us to quantify the amount adsorbed of every component present in the gas mixture. The developed protocol is based on a two-stage stability test. The samples were first exposed to a humid carbon dioxide and helium mixture in order to study the effect of water on the carbon dioxide adsorption capacity of the samples. In the second stage the samples were exposed to a flue gas mixture containing water. From the preliminary water stability test, the Ni-sample exhibited the highest tolerance to the presence of water, retaining approximately 85% of its pristine CO2 capacity. The Mg-MOFs deactivated rapidly in the presence of water. The Ni-CPO-27 was then selected for the second stage of the protocol in which the material was exposed to the wet flue gas. The sample showed an initial drop in CO2 capacity after the first exposure to the wet flue gas, followed by a stabilisation of the performance over several cycles.

Carbon nanotube/PVA aerogels impregnated with PEI: solid adsorbents for CO2 capture

A series of ultra-light aerogels made of oxidized carbon nanotubes and cross-linked polyvinyl alcohol has been prepared by freeze drying of hydrogels, characterised, and tested as amine impregnated solid supports for CO2 capture. The prepared spongy aerogels have demonstrated mechanical, chemical and thermal stabilities, and are electrically conducting. Polyethyleneimine impregnated aerogels with an amine content of 75–83% demonstrated CO2 capacity values ≥3.3 mmol g−1 in a dilute gas stream, which makes the prepared aerogels highly promising supports for amine impregnation in carbon capture applications.

Correction to: A reference high-pressure CO2 adsorption isotherm for ammonium ZSM-5 zeolite: results of an interlaboratory study

The original version of this article was published open access. Unfortunately, due to a technical issue, the copyright holder name in the online version (HTML and XML) is incorrectly published as “Springer Science+Business Media, LLC, part of Springer Nature 2018”. Instead, it should be “The Author(s) 2018”.

Net, Excess and Absolute Adsorption in Mixed Gas Adsorption

The formulation of a thermodynamic framework for mixtures based on absolute, excess or net adsorption is discussed and the qualitative dependence with pressure and fugacity is used to highlight a practical issue that arises when extending the formulations to mixtures and to the Ideal Adsorbed Solution Theory (IAST). Two important conclusions are derived: the correct fundamental thermodynamic variable is the absolute adsorbed amount; there is only one possible definition of the ideal adsorbed solution and whichever starting point is used the same final IAST equations are obtained, contrary to what has been reported in the literature.