Natural gas sweetening using ionic liquids, experiment and modeling

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Natural gas sweetening using ionic liquids, experiment and modeling

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Natural gas sweetening using ionic liquids, experiment and modelingReviewed by رضا فرضی on Feb 26Rating: 5.0Natural gas sweetening using ionic liquids, experiment and modelingNatural gas sweetening using ionic liquids, experiment and modeling

Natural gas sweetening using ionic liquids, experiment and modeling

  1. A. Safavi, C. Ghotbi, 1A. H. Jalili, 1V. Taghikhani

Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran; tel. +9821 66005819, e-mail: ghotbi@sharif.ac.ir; 1Gas Science Department, Research Institute of Petroleum Industry (RIPI), National Iranian Oil Company, Tehran, Iran.

            Ionic liquids (ILs), considered to be a relatively recent magical chemicals due their unique properties, have a large variety of applications in all areas of the chemical industries. The areas of application include electrolyte in batteries, lubricants, plasticizers, solvents and catalysis in synthesis, matrices for mass spectroscopy, solvents to manufacture nano-materials, extraction, gas absorption agents, etc. Non-volatility and non-flammability are their common characteristics giving them an advantageous edge in various applications. This common advantage, when considered with the possibility of tuning the chemical and physical properties of ILs by changing anion–cation combination is a great opportunity to obtain task-specific ILs for a multitude of specific applications. There are numerous studies in the related literature concerning the unique properties, preparation methods, and different applications of ILs in the literature. In this work, a general descriptions of ILs and basic properties of them are given. The main application areas such as solvent replacement, sweetening of natural gase, homogenous and heterogeneous catalysis, biological reactions media and removal of metal ions are discussed in detail. In recent years, some studies have been conducted by our group on the applications of ILs mainly using ILs for gas sweetening. The results of the research and works relating to gas solubility measurement and thermodynamic modeling of gas solubility in ILs will be presented then.

a)The solubility of hydrogen sulfide in three ILs, [bmim][PF6], [bmim][BF4], and [bmim][Tf2N], at temperatures ranging from (303.15 to 343.15) K and pressures up to 1 MPa was determined. The solubility data were correlated using the Krichevsky- Kasarnovsky equation, and Henry’s law constants at different temperatures were obtained [49]. Comparison between Henry’s law constants as a function of temperature for the solubility of H2S and CO2 in those ILs was studied. From the solubility data, the partial molar thermodynamic functions of solution such as Gibbs energy, enthalpy, and entropy were calculated (table 4). Comparison showed that the solubility of H2S in these three ionic liquids was in sequence: [bmim][Tf2N] > [bmim][BF4] > [bmim][PF6].

  1. b) This work focuses on solubility of CO2, H2S and their mixture in the ionic liquid [omim][Tf2N] in the low to medium pressure range (up to about 2.0 MPa) at temperatures from (303.15 to 353.15) K. Because of inconsistency between the Henry’s law constants at zero pressure for solubility of H2S in [hmim][Tf2N] reported in our previous work and the other members of [Cnmim][Tf2N] family, the PTx data for H2S/[hmim][Tf2N] system were again measured in this study. The solubilities determined are used to estimate zero pressure Henry’s law constants and partial molar thermodynamic functions of solution of H2S and CO2 at different temperatures. Correlation equations for the obtained Henry’s law constants with temperature are presented here. Also the solubility of CO2/H2S mixtures in [omim][Tf2N] is investigated in this study to explore the facility of separation of these gases from each other in streams containing them. In the next step, the obtained solubility data are modeled by using two distinct correlation equations, i.e. the extended Henry’s law combined with the Pitzer’s activity coefficient model for electrolytes, which takes into account the non–ideality of solute in liquid solvent through activity coefficients, and a generic Redlich–Kwong type EoS proposed by Shiflett and Yokozeki for gas/ionic liquid systems. The two models are compared with each other and with the simple Krichevsky-Kasarnovsky equation, through comparison of the predicted results with that of experimental data. The experimental results obtained in this work are also compared with the corresponding data for [hmim][Tf2N], [bmim][Tf2N], and [emim][Tf2N] reported in the literature.
رضا فرضی
رضا فرضی
رضا فرضی هستم متولد 71 در شهرستان دیر استان بوشهر، فارغ التحصیل مقطع کارشناسی رشته مهندسی شیمی دانشگاه خلیج فارس بوشهر.
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