Parameterization of COSMO-RS model for ionic liquids

The adjustable parameters in the popular conductor-like screening model for real solvents(COSMO-RS)within the Amsterdam density functional(ADF)framework have been re-optimized to fit for the systems containing ionic liquids(ILs).To get the optimal values of misfit energy constant a^0,hydrogen bond coefficient c_(hb)and effective contact surface area of a segment a_(eff),2283 activity coefficient data points at infinite dilution and 1433 CO_2 solubility data points exhaustively collected from references were used as training set.The average relative deviations(ARDs)of activity coefficients at infinite dilution and CO_2 solubility between experimental data and predicted values are 32.22%and17.61%,respectively,both of which are significantly lower than the original COSMO-RS versions.Predictions for other activity coefficients of solutes in ILs,solubility data of CO_2 in pure ILs and the binary mixtures of ILs at either high or low temperatures,and vapor–liquid equilibrium(VLE)for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs.The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range.The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs,which is always highly desirable for general chemical engineers.

Chlorine drying with hygroscopic ionic liquids

The chlorine(Cl2)drying technology using ionic liquids(ILs)as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level.The hygroscopic IL[EMIM][CH3SO3]was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions,by calculating the Cl2 and H2O solubility and separation selectivity of Cl2 to H2O in different ILs based on the COSMO-RS model.The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses(i.e.,σ-profiles,σ-potentials,excess enthalpies,entropies,and Gibbs free energies)and quantum chemistry calculation(binding energies and weak interaction analyses).The Cl2 solubility in pure IL and H2O+IL systems were predicted by the COSMO-RS model,and the results agree with the microscopic mechanism identification.Moreover,the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation,and continuous Cl2 drying with ILs was conceptually designed and optimized at industrial scale.It was confirmed that[EMIM][CH3SO3]is a very promising absorbent leading to a less IL amount,a much lower energy consumption than the other IL[EMIM][BF4],which has a very bright industrialization potential used for Cl2 drying technology.

Solubility and mass transfer of H2, CH4, and their mixtures in vacuum gas oil: An experimental and modeling study

In this work,the solubility data and liquid-phase mass transfer coefficients of hydrogen(H2),methane(CH4)and their mixtures in vacuum gas oil(VGO)at temperatures(353.15-453.15 K)and pressures(1-7 MPa)were measured,which are necessary for catalytic cracking process simulation and design.The solubility of H2 and CH4 in VGO increases with the increase of pressure,but decreases with the increase of temperature.Henry’s constants of H2 and CH4 follow the relation of In H=-413.05/T+5.27 and In H=-990.67/T+5.87,respectively.The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients.The results showed that with the increase of pressure,the liquid-phase mass transfer coefficients increase.Furthermore,the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model,and the predicted values agree well with experimental data.In addition,the gas-liquid equilibrium(GLE)for H2+CH4+VGO system at different feeding gas ratios in volume fraction(i.e.,H285%+CH415%and H290%+CH410%)was measured.The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data.This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.

Disposal methods for used passenger car tires: One of the fastest growing solid wastes in China

With the rapid growth in the number of passenger cars(PCs)in China over the past decades,more than ten million tons of used tires have already become solid wastes and subsequently caused serious environmental issues.Due to the presence of synthetic rubber in PC tires,waste PC tires cannot be disposed through rubber reclaiming technology.Thus,waste PC tires have become one of fastest growing solid wastes in China.First,the current disposal capacity of the pyrolysis method,regarded as a promising technology for the disposal of waste PC tires,is surveyed and compared with other disposal methods mentioned in previous papers.Second,this work establishes a model to predict the total number of waste PC tires in the next five years depending on the rate of PC growth and current waste tire disposal capacity.Moreover,pyrolysis is evaluated on 15 collected waste PC tires selected from the most representative tire brands in the Chinese market.The corresponding results imply that~68.5%of S was into oil and~44.3%N and large amount of heavy metals resided in solid carbon which severely limit further applications.Finally,a new pyrolysis technology is introduced that may represent a solution to the limits in the application of tire disposal methods and relief for the coming waste tire crisis.