Adsorption of fluorinated greenhouse gases on activated carbons: evaluation of their potential for gas separation

Abstract

Background The increasing awareness of the release of fluorinated gases (F‐gases) into the atmosphere is instigating the development of techniques to capture them from refrigerants. In this work, the adsorption of difluoromethane (R‐32), pentafluoroethane (R‐125), and 1,1,1,2‐tetrafluoroethane (R‐134a) on four different activated carbons (ACs) is studied. Additionally, the selectivity of the ACs for the components of commercial refrigerants, R‐410A and R‐407F, is evaluated. Results The estimation of the density of the adsorbed phase as a function of temperature allows the experimental fractional loading of each F‐gas on any of the ACs to be correlated as a temperature‐independent function of its reduced pressure, which is described by Tóth or dual‐site Langmuir equations or as an exponential function of the adsorption potential under the framework of the Adsorption Potential theory (APT). It is shown that the APT can be generalized with excellent accuracy to the systems studied if an adsorbate‐dependent affinity coefficient is used as a shifting factor to bring the characteristic curves of all F‐gases into a single one for each AC. R‐32 is the F‐gas most adsorbed by all adsorbents, followed by R‐134a, and by R‐125. All ACs are selective for R‐125 in R‐410A commercial refrigerants, especially at lower pressures. Additionally, all ACs are selective for R‐125 and R‐134a over R‐32 in R407‐F commercial refrigerant. Conclusion The utilization of ACs for adsorption of the three most used F‐gases is promising. By selecting ACs with different porous characteristics, it is possible to evaluate their influence on the selectivity for the components of different commercial refrigerants. © 2020 Society of Chemical Industry

Integration of Stable Ionic Liquid-Based Nanofluids into Polymer Membranes. Part I: Membrane Synthesis and Characterization

“…The thermophysical profile of this FIL has been determined in previous works [22][23][24], and its chemical structure is presented in Figure 1a. The values of [C2C1py] [C4F9SO3] at 30 °C used in this work were: density 1.51 g•cm −3 , viscosity 150.3 mPa•s, and molar volume 279.01 cm 3 •mol −1 .…”

“…Then, the Fgases atmospheric emissions must imperatively be reduced, in accordance with the Kyoto protocol, further developed by the Kigali agreement (international agreement specific for these compounds signed in 2016) and the most recent EU regulation [1]. The development of more benign and efficient materials designed according to the principles of green chemistry [2,3] to recover fluorinated gases used in refrigeration and air conditioning [4] and reducing their emissions are the objectives of this study.…”

Waste Management Strategies to Mitigate the Effects of Fluorinated Greenhouse Gases on Climate Change

“…Moreover, these systems require low maintenance and have a long lifetime [58,59]. One of the technologies is based on adsorption processes, in which one of the components of the mixture is preferentially adsorbed into a porous material while the remaining leaves the adsorption column, including the regeneration of the adsorption column to recover the adsorbed gas [60]. The other technology is based on the separation by a membrane, in which one compound of the mixture is preferentially permeated through highly selective thin films due to differences in the size of the gas molecules and to gas-membrane interactions [61].…”

Characterization of Local Structures of Confined Imidazolium Ionic Liquids in PVdF-co-HFP Matrices by High Pressure Infrared Spectroscopy

“…Based on the versatility of ionic liquids (ILs), there is the possibility of obtaining ILs with high ionic conductivities, large electrochemical windows, great thermal stability, gas adsorption, non-flammability, and low toxicity [ 14 , 15 , 16 , 17 , 18 ]. Some researchers have suggested that heterocyclic-based ILs such as alkyl-methyl-imidazolium ILs, are possible choices for polymer electrolytes due to the ease with which their physical properties can be modified [ 7 , 19 ].…”