Adsorption Separation of R-22, R-32 and R-125 Fluorocarbons using 4A Molecular Sieve Zeolite

Global warming has received great attention over the past decades, which is having costly impacts on our communities, health and climate. Fluorocarbon derivatives that are widely used in various industries such as refrigerants and solvents have significant effect on global warming due to their high global warming potential. Recycling and reuse of fluorocarbons help not only to minimize the environmental release but also to fulfill the future demand with the rapid phase out of some of the fluorocarbons. Herein, our work reports the adsorption separation of mixtures of difluoromethane (R-32), chlorodifluoromethane (R-22) and pentafluoroethane (R-125) into their pure components using 4A molecular sieve zeolite under ambient conditions. Pure gas equilibrium isotherm measurements indicate that the uptake capacity follows the order of R-32 > R-22 > R-125 on 4A zeolite with negligible uptake capacity for R-125. As evidenced by the gas breakthrough results, R-32, R-22 and R-125 could be successfully separated into pure components using 4A zeolite. Steric effects were responsible for the separation of R-32 and R-22 from R-125 while slower uptake rate of R-22 compared to R-32 facilitated the successful separation of R-22 from R-32. The regular pore structure, excellent match of pore size of 4A zeolite with the molecular sizes of the fluorocarbon make the product gases very pure, to the extent of direct industrial applications.  © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim