Experimental solubilities of difluoromethane (R32) in polyol ester (POE), polyvinylether (PVE), and polyalkylene glycol (PAG) base oils were measured in the temperatures range from 273 K to 351 K based on the isochoric method. The experimental setup was checked by measuring the solubility of carbon dioxide in n -decane at pressures from 0.1 to 4.6 MPa. The expanded uncertainty ( k = 2) of the measured solubility data was estimated to be less than 2.8%. The experimental solubility data were correlated using the Peng–Robinson (PR) equation of state (EOS) and Wilson activity coefficient model. The absolute average deviations of the experimental data and calculated values for R32 in POE, PVE, and PAG base oils were 1.74%, 0.73%, and 0.97%, respectively. The solubility of R32 in three base oil were calculated and compared at same temperatures and pressures, and the results showed that the solubility order of R32 in the three base oils was: PAG > PVE > POE.
Trifluoromethane is one of the most potent and stable greenhouse gases with global warming potential of 14,800 times higher than CO 2 (100-year time horizon). At present, it is destroyed by incineration or plasma at temperatures above 1200 K. For the first time, this work report that CHF 3 can be reverted to HCFC-22 via the intermolecular Cl/F exchange reaction of CHF 3 with CHCl 3 over AlF 3 catalyst under moderate conditions. As CHF 3 is produced during the manufacture of HCFC-22 via the fluorination of CHCl 3 in liquid phase, no additional feedstock and products are involved for the treatment of CHF 3 in this proposed process. At 593 K and atmospheric pressure, CHF 3 conversion levels of about 18%–20% are achieved and no significant deactivation is observed following time on stream of 100 h. In addition, the catalytic reaction mechanism is proposed. According to the experiments and DFT calculation, the intermolecular Cl/F exchange reaction of CHF 3 with CHCl 3 is mainly initiated by the breakage of C Cl. The present work provides a potential resource utilization route for the treatment of CHF 3 and other hydrofluorocarbons (HFCs).
Difluoromethane (R32) is a good additive to improve the coefficient of performance (COP) of hydrofluoroolefins (HFOs) which are the next generation of refrigerants. Therefore, it is important to efficiently recover Difluoromethane (R32) from R410A(a blend of 50 % R32 and 50 % pentafluoroethane (R125)) which will be eliminated due to high global warming potential (GWP). In this work, fluorinated UiO-66 was synthesized by replacing the terephthalic acid ligand in UiO-66 with an organic ligand containing fluorocarboxylic acids to enchance the separation performance of mixed matrix membranes (MMMs) as filler, and the effect of the fluorine content of the fluorinated UiO-66 was investigated. In this study, Fluorinated UiO-66/Pebax MMMs were successfully prepared, with the fluorine content tailored by using different ligands. The separation performance increased with the amount of fluorine in the MOFs, namely UiO-66-(CF 3 ) 2 /Pebax > UiO-66-F 4 /Pebax > UiO-66-F 2 /Pebax > UiO-66-F/Pebax > UiO-66/Pebax MMMs. The 20 wt% UiO-66-(CF 3 ) 2 /Pebax achieved an ultra-high P R32 of 979.53 Barrer (397 % of pure Pebax membrane) while maintaining a high ɑ R32/R125 (16.64, 251 % of pure Pebax membrane).The tested results showed that the fluorinated UiO-66/Pebax MMMs sigificantly improved permeability and selectivity for R410A due to the higher R32 solubility caused by C-F…H hydrogen bonding network formed between the fluorine groups and R32 as well as the better sieving ability caused by the decrease in the pore size of UiO-66. The fluorinated MOFs/Pebax MMMs prepared in this work simultaneously achieved better R32/R125 selectivity and R32 permeability,than the exsited membranes, enabling effective separation and recycle R32 from R410A.
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