A review of fluorocarbon sorption on porous materials

https://doi.org/10.1016/j.micromeso.2021.111654Get rights and content

Highlights

  • Comprehensive review of fluorocarbon sorption with 367 sources from 1947 to present.

  • Discusses capture, purification, separation, adsorption-refrigeration, nanofluids, catalysis, and fundamental studies.

  • More than 10 sorbents mentioned including zeolites, activated carbons, and metal-organic frameworks (MOFs).

  • Includes over 100 fluorocarbons consisting of CFCs, CFOs, HCFCs, HCFOs, HFCs, HFOs, PFCs, and PFOs.

  • Highlights the use of over 15 adsorption isotherms for modeling fluorocarbon sorption with different sorbents.

Abstract

Fluorocarbons have commonly been used for refrigerants, coolants, fire-suppressants, propellants, semiconductors, fluoropolymers, and other applications since the early 20th century. However, starting in the late 1980s these chemicals have been highly regulated due to environmental concerns over ozone depletion potential (ODP) and global warming potential (GWP). Porous materials such as zeolites, activated carbons, and metal-organic frameworks (MOFs) are among the current sorbents being studied to reduce emissions of greenhouse gases (GHGs) including fluorocarbons and carbon dioxide. Recent legislation now requires the reduction of hydrofluorocarbon refrigerants over the next two decades to reduce global warming which makes environmental remediation a relevant issue. An extensive literature search has been conducted for fluorocarbon sorption in porous materials to better understand current and prior separation technologies that can reduce climate change. This review article discusses applications for which fluorocarbon sorption is reported and encompasses both academic and patent literature from the late 1940s to present. Pure gas sorption of straight-chain paraffinic and olefinic fluorocarbons as well as zeotropic, azeotropic, and isomeric mixture separations is reviewed. Additional topics including molecular interactions, reactivity, and molecular modeling are discussed in detail.

Introduction

Global refrigerant usage encompasses a growing number of applications that are critical to modern society. The past two centuries have seen the birth and rapid growth of refrigerant technologies, starting with Jacob Perkins who created a vapor-compression refrigeration cycle using liquid ammonia in the 1830s (first-generation refrigerant) [1]. By the 1930s, Thomas Midgely, Albert L. Henne, and Robert R. McNary had discovered fluorocarbon refrigerants, leading to the widespread use of chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants (second-generation refrigerants) [1]. However, by the mid-1980s, CFCs were linked to the depletion of the Earth's ozone layer [2]. In 1987, the Montreal Protocol was signed limiting the production of ozone depleting substances such as CFCs [1,3]. In 1992, the Copenhagen amendment to the Montreal protocol called for the phaseout of HCFCs by the year 2030 [3]. The phaseout of CFCs and HCFCs led to the development of hydrofluorocarbon (HFC) refrigerants which have zero ozone depletion potential (ODP) [1]. HFCs are considered third-generation refrigerants and have been in production and use for the past thirty years.

Today, concerns over the global warming potential (GWP) of HFCs has become an issue [1]. In fact, some HFCs contribute thousands of times more to global warming than carbon dioxide on an equivalent mass basis. A list of some common HFCs and their GWPs is given in Table 1. In the global effort to mitigate climate change, a series of legislative actions have been taken that affects HFC use and production. The Kyoto Protocol in 2005 [1], F-gas regulations by the European Union in 2014 [1], the Kigali Amendment to the Montreal Protocol in 2016 [4], and the American Innovation and Manufacturing (AIM) act in 2020 [5] are among the most recent actions taken to phase out and limit the use of HFCs. As a result of the phaseout of HFCs, the transition to fourth-generation refrigerants is currently underway. Many of these refrigerants are based on hydrofluoroolefins (HFOs) that have a zero ODP and low GWP (Table 1) [1].

As the air-conditioning and refrigeration (RAC) industry transitions to HFOs, something must be done with the estimated 2800 ktons of refrigerant currently in use globally [6]. Opposed to venting or incinerating these high GWP refrigerants, a more preferable route would be to reclaim, separate, and recycle them. However, this process is becoming more difficult due to the similar thermophysical properties of HFC mixture components and the azeotropic nature of many of these HFC blends. Cryogenic distillation can perform some separations but is highly energy intensive and not effective at separating azeotropic compositions [[7], [8], [9], [10]]. However, the use of zeolites and activated carbons has been reported in the patent literature for separating azeotropic refrigerant mixtures [7]. Wanigarathna et al. have recently shown that it is possible to use both zeolites and metal-organic frameworks (MOFs) to separate azeotropic HFC refrigerant mixtures [[11], [12], [13]].

The use of sorbents for the separation of HFC refrigerant mixtures based on differences in molecular size and interactions is a promising, less energy-intensive alternative to conventional distillation processes. An extensive literature search has been performed for fluorocarbon sorption on porous materials. Literature and patent data have been found on the sorption of fluorocarbons including CFCs, chlorofluoroolefins (CFOs), HCFCs, hydrochlorofluoroolefins (HCFOs), HFCs, HFOs, perfluorocarbons (PFCs), and perfluoroolefins (PFOs) in porous materials such as zeolites, activated carbons, and metal organic frameworks (MOFs). Only one known review article has been found for fluorocarbon sorption and the scope is limited to sorption and separation of CFCs, HCFCs, HFCs, and PFCs with MOFs [14].

This review is organized such that the reader can easily find the topic of interest. For example, discussion on HFC sorption using zeolites is provided in Sections 7.1 (applications) and 7.2 (sorption behavior). These sections are further divded by specific applications (Sections 1 Introduction, 2 Sorbents, 3 Overview of literature, 4 Refrigerant nomenclature, 5 Chlorofluorocarbons (CFCs), 6 Hydrochlorofluorocarbons (HCFCs) and hydrochlorofluoroolefins (HCFOs), 7 Hydrofluorocarbons (HFCs)), molecular interactions (Section 7.2.1), isotherm modeling (Section 7.2.2), and reactivity (Section 7.2.3). Sections 5 Chlorofluorocarbons (CFCs), 6 Hydrochlorofluorocarbons (HCFCs) and hydrochlorofluoroolefins (HCFOs), 8 Hydrofluoroolefins (HFOs), 9 Perfluorocarbons (PFCs) and perfluoroolefins (PFOs) follow similar formatting for CFCs, HCFCs and HCFOs, HFOs, and PFCs and PFOs, respectively. This review article provides a comprehensive overview of fluorocarbon sorption and separation that can be valuable to researchers both new to the field and those having years of experience. Sorbents offer a wide range of tunable physical and chemical properties and provide an opportunity to lower the energy required for separation of fluorocarbons.

Section snippets

Sorbents

The most common sorbents found for fluorocarbon sorption include activated carbons, zeolites, and metal-organic frameworks (MOFs). A brief description about each type of sorbent is provided to familiarize the reader with some key attributes for each material. A section is also included to highlight features of sorbents that influence sorption. A comparison among zeolites, activated carbons, and MOFs is provided in Table 2. Other sorbents found less frequently in the literature for fluorocarbon

Overview of literature

An extensive literature search was conducted for fluorocarbon sorption from both academic papers and patent literature with a primary focus on sorption of straight-chain paraffinic and olefinic fluorocarbons. In this context, fluorocarbons refer to species having the following chemical formula:CxHyFzClk;x,z0

Fluorocarbons are hydrocarbon-based species that contain at least one fluorine atom, but can also contain hydrogen atoms, chlorine atoms, both, or neither.

The frequency for which zeolites,

Refrigerant nomenclature

Fluorocarbons are frequently referred to by a nomenclature developed by DuPont and adopted by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) [36]. This nomenclature will be used throughout this review article and thus it is worth briefly mentioning here. A fluorocarbon can be referred to by one of the following formats:

R-X

Fluorocarbon Code-X

Here, “Fluorocarbon Code” is the type of fluorocarbon i.e., CFC, CFO, HCFC, HCFO, HFC, HFO, PFC, or PFO. Both of

Chlorofluorocarbons (CFCs)

A sampling of representative CFCs is tabulated and provided in the Supplementary Material along with values for gas-phase dipole moment (μg) and the polarizability (α) (see Table S2). CFCs are found to have much lower permanent dipole moments compared with other fluorocarbons; however, CFCs tend to have much greater polarizability, which arises from the chlorine atoms. The lack of dipole moment results from the fact that chlorine and fluorine atoms have similar electronegativities. A list of

Hydrochlorofluorocarbons (HCFCs) and hydrochlorofluoroolefins (HCFOs)

Examples of HCFCs and an HCFOs are provided in the Supplementary Material with values for gas-phase dipole moment (μg) and polarizability (α) (see Table S7). The dipole moments of HCFCs are much larger than CFCs and slightly less than HFCs on average. HCFCs also have polarizabilities slightly lower than CFCs and much larger than HFCs. HCFCs exhibit molecular properties of both CFCs and HFCs. A list of reported sorbents for HCFC and HCFO sorption and applications is provided in Table 4. Only two

Hydrofluorocarbons (HFCs)

Examples of HFCs are provided in the Supplementary Material with values for gas-phase dipole moment (μg) and polarizability (α) (see Table S12). HFCs have among the largest dipole moments and the smallest polarizabilities of the fluorocarbons and can be considered as rigid, hard spheres and ovals with distinct positive and negative ends. A list of reported sorbents for HFC sorption with applications is presented in Table 5. A breakdown of the sources that report the use of zeolites, activated

Hydrofluoroolefins (HFOs)

Examples of HFOs are provided in the Supplementary Material with values for gas-phase dipole moment (μg) and polarizability (α) (see Table S18). HFOs generally have both the largest dipole moments and polarizabilities among the fluorocarbons discussed. The large dipole moments result from the large electronegativity difference between hydrogen and fluorine atoms (as is the case with HFCs). The double bonds of HFOs contribute toward large polarizability. A list of reported sorbents for HFO

Perfluorocarbons (PFCs) and perfluoroolefins (PFOs)

Examples of PFCs and PFOs are provided in the Supplementary Material with values for gas-phase dipole moment (μg) and polarizability (α) (see Table S20). PFCs contain only carbon and fluorine atoms and are symmetrical giving them zero permanent dipole moments. PFOs are not always symmetrical and can therefore have weak permanent dipole moments. The polarizability of PFCs and PFOs increases with an increasing number of fluorine atoms.

A list of sorbents for PFC and PFO sorption along with

Discussion of chemical interactions

Molecular interactions have been discussed for zeolites, activated carbons, and MOFs with CFCs, HCFCs, HCFOs, HFCs, HFOs, and PFCs. Both dipole moment and polarizability were often used to justify sorption behavior and will now be used to highlight sorption trends noticed from previous discussion. Basic zeolites (e.g., 5A and 13X) and MOFs with high density OMSs (e.g., Ni-MOF-74) generally had greater affinity toward species with larger dipole moments, that is, HFCs, HFOs, and some HCFCs. The

Mixtures

The following section discusses separations of mixtures consisting of two or more fluorocarbons and provides multiple examples of sorbents in practical use. Examining the outcome of separated mixtures is also useful for understanding the effects of molecular interactions between fluorocarbons and sorbents. For example, Section 10 noted that untreated activated carbons generally have greater affinity for CFCs over HFCs; therefore, under normal conditions the retention time should be greater for

Conclusion

This review article explores the applications, molecular interactions, isotherm modeling, and reactivity of various sorbents and fluorocarbons as well as the separation and purification of fluorocarbon mixtures. Fluorocarbon sorption was found to be a well-studied field starting in the 1940s and continues today. A common theme found throughout fluorocarbon sorption literature and patents was environmental remediation, which has directly influenced a majority of the studies. Academic papers have

CRediT authorship contribution statement

Andrew D. Yancey: Conceptualization, Methodology, Investigation, Data Curation, Writing-Original Draft, Writing-Review & Editing, Visualization. Sophia J. Terian: Conceptualization, Writing-Original Draft. Benjamin J. Shaw: Data Curation. Tiana M. Bish: Data Curation. David R. Corbin: Conceptualization, Methodology, Supervision, Writing-Review & Editing. Mark B. Shiflett: Conceptualization, Methodology, Supervision, Funding Acquisition, Writing-Review & Editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This material is based upon work supported by the National Science Foundation under grant no. 2029354.

References (352)

  • M. Sugimoto et al.

    Improvement of platinum-supported zeolite catalysts for n-hexane aromatization by halocarbon treatment and alkaline soaking

    Appl. Catal. A Gen.

    (1993)
  • K. Mizukami et al.

    Atomistic mechanism of the adsorption of CFCs in zeolite as investigated by Monte Carlo simulation

    Stud. Surf. Sci. Catal.

    (1997)
  • S.Y. Cho

    A study on adsorption of trichloromonofluoroethane by an activated carbon pellet

    Carbon

    (1995)
  • S.Y. Cho

    Adsorption of chlorofluorocarbons on microporous carbon fiber

    Carbon

    (1994)
  • S.Y. Cho

    The effect of presorbed water on the adsorption of CFC-113 by a carbon adsorbent

    Carbon

    (1995)
  • N. Kawasaki et al.

    The recovery of chlorofluorocarbons and chlorofluorocarbon replacements by surface modified activated carbon

    J. Colloid Interface Sci.

    (1995)
  • S. Tanada et al.

    Adsorption properties of CFC and CFC replacements on activated carbon containing introduced ionic fluoride and chloride

    J. Colloid Interface Sci.

    (1996)
  • D.J. Moon et al.

    Adsorption equilibrium and catalytic reaction of CFC-115 on Pd/activated carbon powder

    Carbon

    (1999)
  • X. Zhang et al.

    Adsorption dynamics of trichlorofluoromethane in activated carbon fiber beds

    J. Hazard Mater.

    (2011)
  • J. Ruan et al.

    Environmental friendly automated line for recovering the cabinet of waste refrigerator

    Waste Manag.

    (2011)
  • R. Forsythe et al.

    The volume Adsorption capacity of activated carbon for selected trace contaminates

    Carbon

    (1978)
  • R.J. Cicerone et al.

    Stratospheric ozone destruction by man-made chlorofluoromethanes

    Science

    (1974)
  • B.J. Gareau

    A critical review of the successful CFC phase-out versus the delayed methyl bromide phase-out in the Montreal Protocol, Int. Environ. Agreem

  • G.M. Rusch

    The development of environmentally acceptable fluorocarbons

    Crit. Rev. Toxicol.

    (2018)
  • H. R. 133, One Hundred Sixteenth Congress of the United States of America

    (2021)
  • C. Booten et al.

    Refrigerants: Market Trends and Supply Chain Assessment; NREL/TP-5500-70207

    (Feb. 2020)
  • N.C. Stephenson et al.

    Refrigerant separation

    Colcard Pty. Limited

    (1996)
  • H. Ohno et al.

    Process for purifying pentafluoroethane, process for producing the same, and use thereof

    Showa Denko K.K

    (Aug. 1, 2006)
  • D.R. Corbin et al.

    Separation of chloropentafluoroethane from pentafluoroethane

    E. I. du Pont de Nemours and Company

    (Dec. 17, 1996)
  • G.J. Moore

    Purification Process. Imperial Chemical Industries Plc

    (May 11, 1993)
  • D. Wanigarathna et al.

    Adsorption separation of R-22, R-32 and R-125 fluorocarbons using 4A molecular sieve zeolite

    ChemistrySelect

    (2016)
  • D. Wanigarathna et al.

    Adsorption separation of R134a, R125 and R143a fluorocarbon mixtures using 13X and surface modified 5A zeolites

    AIChE J.

    (2017)
  • D. Wanigarathna et al.

    Fluorocarbon separation in a thermally robust zirconium carboxylate metal-organic framework

    Chem. Asian J.

    (2018)
  • J. Schwarcz

    Charcoal is one of the most important substances ever discovered

    Office for Science and Society

    (2017)
  • S. Bubanale et al.

    History, method of production, structure and applications of activated carbon

    IJERT

    (2017)
  • K. Koehlert

    Activated carbon: fundamentals and new applications

  • D.W. Breck

    Zeolite Molecular Sieves: Structure, Chemistry, and Use

    (1974)
  • W. Loewenstein

    The distribution of aluminum in the tetrahedra of silicates and aluminates

    Am. Mineral.

    (1954)
  • R.C. Deka

    Acidity in zeolites and their characterization by different spectroscopic methods

    Indian J. Chem. Technol.

    (1998)
  • Q. Fu et al.

    Competitive adsorption mechanism study of CHClF2 and CHF3 in FAU zeolite

    ACS Sustain. Chem. Eng.

    (2018)
  • C. Mellot-Draznieks et al.

    Adsorption of chlorofluorocarbons in nanoporous solids; a combined powder neutron diffraction and computational study of CFCl3 in NaY zeolite

    Phys. Chem. Chem. Phys.

    (2003)
  • P. Bai et al.

    Discovery of optimal zeolites for challenging separations and chemical transformations using predictive materials modeling

    Nat. Commun.

    (2015)
  • Fundamentals and Applications

    (2019)
  • H. Furukawa et al.

    The chemistry and applications of metal-organic frameworks

    Science

    (2013)
  • U. Kokcam-Demir et al.

    Coordinatively unsaturated metal sites (open metal sites) in metal-organic frameworks: design and applications

    Chem. Soc. Rev.

    (2020)
  • Adsorption and Diffusion, Springer-Verlag, Berlin/Heidelberg

    (2008)
  • R.N. Eissmannt et al.

    Coadsorption of organic compounds and water vapor on BPL activated carbon. 2. 1,1,2-Trichloro-1,2,2-trifluoroethane and dichloromethane

    Ind. Eng. Chem. Res.

    (1993)
  • J.B. Rawlings et al.

    Chemical Reactor Analysis and Design Fundamnetals

    (2012)
  • Refrigerating, and air-conditioning engineers; designation and safety classification of refrigerants

    ANSI/ASHRAE Standard

    (2019)
  • Cited by (27)

    View all citing articles on Scopus
    View full text