A review of fluorocarbon sorption on porous materials

Yancey, Andrew D.; Terian, Sophia J.; Shaw, Benjamin J.; Bish, Tiana M.; Corbin, David R.; Shiflett, Mark B.

doi:10.1016/j.micromeso.2021.111654

Cited by 48 publications

(40 citation statements)

References 210 publications

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“…The strong affinity for both HFC-32 and HFC-125 with LTA zeolites agrees with previous studies that include HCFCs, HFCs, and basic zeolites (e.g., LTA and FAU zeolites). 2 The low sorption of HFC-125 on zeolites 4A and 3A is not surprising considering that the pore diameters for zeolites 4A and 3A are approximately 4 and 3 Å, respectively, and the kinetic diameter of HFC-125 is 4.4 Å. 3 It is possible that the sorption observed for HFC-125 in Figures 2 and 3 corresponds to sorption on the external surface area of the sorbent.…”

Section: ■ Models Materials and Methodsmentioning

confidence: 96%

Difluoromethane (HFC-32) and Pentafluoroethane (HFC-125) Sorption on Linde Type A (LTA) Zeolites for the Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures

2022

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Worldwide use of hydrofluorocarbons (HFCs) is currently being regulated and phased out because of high global warming potentials (GWPs). Separation techniques for recycling refrigerants are needed so that HFCs can be dealt with responsibly. Many HFCs currently in use are azeotropic or near-azeotropic refrigerant blends and must be separated so that the components can be recycled and repurposed effectively. One such refrigerant is R-410A, which is a near-azeotropic 50/50 wt % mixture of pentafluoroethane (HFC-125) and difluoromethane (HFC-32). This study examined the use of the LTA zeolites for separating HFC-32 from HFC-125. Pure gas isotherms were measured using a XEMIS gravimetric microbalance with zeolites 3A, 4A, and 5A. Reversible sorption was observed for HFC-32 with zeolites 4A and 5A, whereas irreversible sorption was observed for HFC-125 with zeolite 5A. Negligible sorption was observed for HFC-125 with zeolites 3A and 4A, and although sorption of HFC-32 with zeolite 3A was observed, the process was slow, making the sorbent not commercially viable. The enthalpy of adsorption was predicted using the vapor adsorption equilibrium (VAE) analogue of the Clausius−Clapeyron equation and measured using a calorimeter for HFC-125 and HFC-32 with zeolite 5A and for HFC-32 with zeolite 4A. Molecular-level interactions between the LTA zeolites and HFCs were discussed and used to interpret pure gas isotherms and enthalpy of adsorption results. Overall, zeolites 4A and 5A were found to be good candidates for kinetically and thermodynamically separating R-410A, respectively.

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Section: ■ Models Materials and Methodsmentioning

confidence: 96%

Difluoromethane (HFC-32) and Pentafluoroethane (HFC-125) Sorption on Linde Type A (LTA) Zeolites for the Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures

2022

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“…Fluorocarbons are of particular interest since these chemicals are used in a variety of applications, including air-conditioning, refrigeration, fire suppression, aerosols, and etchants for the semiconductor industry. Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were the first fluorocarbons used as refrigerants starting in the 1930s; however, CFCs were phased out by the Montreal Protocol in 1987, followed by HCFCs in 1992 by the Copenhagen Amendment to the Montreal Protocol, after both were linked to the depletion of the Earth’s ozone layer . Hydrofluorocarbons (HFCs) replaced CFCs and HCFCs starting in the mid-1980s, but many HFCs have high global warming potentials (GWPs).…”

Section: Introductionmentioning

confidence: 99%

“…However, performing such separations to obtain high-purity products is difficult because of the similar chemical properties and boiling points of many HFCs and HCFCs. While distillation techniques have been found to be energy-intensive or require the use of entrainers, − adsorption-based technology is a less energy-intensive process that has been proven to effectively separate both azeotropic and isomeric mixtures. − Extensive review articles by Wanigarathna et al and Yancey et al discuss fluorocarbon adsorption and separation using adsorbents.…”

Section: Introductionmentioning

confidence: 99%

“…Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were the first fluorocarbons used as refrigerants starting in the 1930s; however, CFCs were phased out by the Montreal Protocol in 1987, followed by HCFCs in 1992 by the Copenhagen Amendment to the Montreal Protocol, after both were linked to the depletion of the Earth's ozone layer. 2 Hydrofluorocarbons (HFCs) replaced CFCs and HCFCs starting in the mid-1980s, but many HFCs have high global warming potentials (GWPs). A list of commonly used HFCs including GWPs and normal boiling points (NBPs) is provided in the Supporting Information (see Table S1).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Legislation phasing out HFCs has increased in the last two decades and includes the Kyoto Protocol in 2005, F-gas regulations by the European Union in 2014, the Kigali Amendment to the Montreal Protocol in 2016, and the American Innovation and Manufacturing (AIM) act in 2020. 2 A report published by the National Renewable Energy Lab (NREL) in 2020 estimates that there are currently 2800 ktons of refrigerant in use globally and that most of this refrigerant consists of HCFCs and HFCs. 3 As a result, an increasingly large supply of both HCFC and HFC refrigerant will need to be dealt with as legislation continues to phase them out.…”

Section: ■ Introductionmentioning

confidence: 99%

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Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures: Thermodynamic and Kinetic Modeling for Binary Adsorption of HFC-32 and HFC-125 on Zeolite 5A

et al. 2022

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Hydrofluorocarbons (HFCs) have been used extensively as refrigerants over the past four decades; however, HFCs are currently being phased out due to large global warming potentials. As the next generation of hydrofluoroolefin refrigerants are phased in, action must be taken to responsibly and sustainably deal with the HFCs currently in circulation. Ideally, unused HFCs can be reclaimed and recycled; however, many HFCs in circulation are azeotropic or near-azeotropic mixtures and must be separated before recycling. Previously, pure gas isotherm data were presented for both HFC-125 (pentafluoroethane) and HFC-32 (difluoromethane) with zeolite 5A, and it was concluded that this zeolite could separate refrigerant R-410A (50/50 wt % HFC-125/HFC-32). To further investigate the separation capabilities of zeolite 5A, binary adsorption was measured for the same system using the Integral Mass Balance method. Zeolite 5A showed a selectivity of 9.6–10.9 for HFC-32 over the composition range of 25–75 mol % HFC-125. Adsorbed phase activity coefficients were calculated from binary adsorption data. The Spreading Pressure Dependent, modified nonrandom two-liquid, and modified Wilson activity coefficient models were fit to experimental data, and the resulting activity coefficient models were used in Real Adsorbed Solution Theory (RAST). RAST binary adsorption model predictions were compared with Ideal Adsorbed Solution Theory (IAST) predictions made using the Dual-Site Langmuir, Tóth, and Jensen and Seaton pure gas isotherm models. Both IAST and RAST yielded qualitatively accurate predictions; however, quantitative accuracy was greatly improved using RAST models. Diffusion behavior of HFC-125 and HFC-32 was also investigated by fitting the isothermal Fickian diffusion model to kinetic data. Molecular-level phenomena were investigated to understand both thermodynamic and kinetic behaviors.

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Size‐Selective Capture of Fluorocarbon Gases and Storage of Volatile Halogenated Organic Vapors with Low Boiling Points by Molecular‐Scale Cavities of Crystalline Pillar[n]quinones

Ohtani,

Onishi,

Wada

et al. 2023

Adv Funct Materials

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Fluorocarbon gases are regarded as one of the largest contributors to serious environmental problems such as ozone‐depletion and global warming, and thus, the development of reclamation technologies is in great demand for reducing emission of such harmful compounds. So far, porous materials such as zeolites, activated carbons, and metal‐organic frameworks (MOFs) have been examined as solid‐state absorbents for fluorocarbon gases. However, such porous materials often suffer from a lack of size‐selectivity in fluorocarbon gas uptakes due to the large‐sized cavities (>1 nm). Herein, it is reported that macrocyclic pillar[n]quinones (P[n]Q, n = 5 or 6) in crystalline state show size‐selective uptake for fluorocarbon gases owing to their molecular‐scale cavities (<1 nm). The P[n]Q also show uptake behaviors for volatile halogenated organic compounds (VHOCs), which are highly toxic. Interestingly, the volatilities of VHOCs within the 1D channels of P[5]Q are drastically reduced compared with those of the bulk VHOC solvents. Experimental results and computational analyses revealed that the excellent storage abilities of the crystalline P[n]Q are a synergic result of their electron‐deficient macrocyclic scaffolds and the basic carbonyl oxygen atoms on their rims.

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A review of fluorocarbon sorption on porous materials

Cited by 48 publications

References 210 publications

Difluoromethane (HFC-32) and Pentafluoroethane (HFC-125) Sorption on Linde Type A (LTA) Zeolites for the Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures

Difluoromethane (HFC-32) and Pentafluoroethane (HFC-125) Sorption on Linde Type A (LTA) Zeolites for the Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures

Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures: Thermodynamic and Kinetic Modeling for Binary Adsorption of HFC-32 and HFC-125 on Zeolite 5A

Size‐Selective Capture of Fluorocarbon Gases and Storage of Volatile Halogenated Organic Vapors with Low Boiling Points by Molecular‐Scale Cavities of Crystalline Pillar[n]quinones

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