I. V. Vorotyntsev

High purification of gas in radial membrane element

The process of high purification of gas from easily penetrating impurities in a countercurrent radial membrane element is investigated theoretically and experimentally. The mathematical model of process is developed in view of longitudinal mixing impurities in both cavities of an element, and with the consider recycle of a target flow from a cavity of high in a cavity of low pressure (retentate recycle). It is found that, the researched membrane elements have the high separation power. It is shown that the retentate recycle should be realized in membrane elements with high-selectivity and low permeability of the basic component membranes. The experimental and the calculation results are in agreement.

Sorption of ammonia and nitrogen on cellulose acetate

Adsorption isotherms of ammonia and nitrogen on cellulose acetate in the temperature range 303–333 K are measured by reversed-phase chromatography. It is established that ammonia specifically interacts with the polymer matrix of the sorbent. The experimental data are described in terms of the Laatikainen-Lindstrom quasi-chemical model of vapor sorption. The enthalpies of sorption are determined, and their dependences on the ammonia and nitrogen concentrations in the sorbent are established.

Preparation and Characterization of Facilitated Transport Membranes Composed of Chitosan-Styrene and Chitosan-Acrylonitrile Copolymers Modified by Methylimidazolium Based Ionic Liquids for CO2 Separation from CH4 and N2

CO2 separation was found to be facilitated by transport membranes based on novel chitosan (CS)–poly(styrene) (PS) and chitosan (CS)–poly(acrylonitrile) (PAN) copolymer matrices doped with methylimidazolium based ionic liquids: [bmim][BF4], [bmim][PF6], and [bmim][Tf2N] (IL). CS plays the role of biodegradable film former and selectivity promoter. Copolymers were prepared implementing the latest achievements in radical copolymerization with chosen monomers, which enabled the achievement of outstanding mechanical strength values for the CS-based membranes (75–104 MPa for CS-PAN and 69–75 MPa for CS-PS). Ionic liquid (IL) doping affected the surface and mechanical properties of the membranes as well as the gas separation properties. The highest CO2 permeability 400 Barrers belongs to CS-b-PS/[bmim][BF4]. The highest selectivity α (CO2/N2) = 15.5 was achieved for CS-b-PAN/[bmim][BF4]. The operational temperature of the membranes is under 220 °C.

The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes.

Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N2, NH3, H2S, and CO2 gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF6] and [emim][Tf2N]. The modification of SILMs by nanosize silica particles leads to an increase of NH3 separation relatively to CO2 or H2S.

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank has been considered. Two modes of the process has been studied, one with a constant degree of separation in the membrane module and the other with a constant concentration of impurities in the stream directed to the receiver tank. The degree of removal and the time of the process have been calculated. It has been shown that the second mode is somewhat more cost-effective because of the lack of mixing of streams with different concentrations and the absence of the lost work of separation.

Fine Purification of Silane for Removal of Chlorosilanes by Membrane Gas Separation

The membrane separation of a silane, dichlorosilane, trichlorosilane, and tetrachlorosilane gas mixture has been theoretically and experimentally studied. The ideal separation factors have been determined experimentally and their values in the separation cell at pressures P1 and P2 have been found. The separation factor has been calculated for different ratios of flows in the compartments of a membrane module. The silane cleaning process for the removal of highly penetrating impurities in a radial membrane module and in a membrane module with a feed tank has been calculated.

Nitrous oxide high purification by membrane gas separation

In this work the scope of nitrous oxide high purification by membrane gas separation was presented. The permeability values of nitrous oxide and its limiting impurities were measured for “Lestosil” membrane at feed pressure in the range from 100 to 400 kPa. The values of ideal selectivity were determined. It was shown that nitrous oxide is more permeable than impurities components. Therefore the process of nitrous oxide high purification was calculated for it carried out in membrane module with a feeding reservoir which is used for purification from low permeable impurities.

Separation and concentration of a low-penetrating impurity by membrane gas separation

The process of concentrating low-penetrating impurities in membrane modules was studied theoretically and experimentally. An expression was derived for the degree of separation in a radial cross-flow module; the degree of separation substantially depends on the gas-phase diffusion coefficient of the impurity. The experimental results obtained for a mixture of carbon dioxide with an impurity of Freon 14 and a mixture of Freon 12 with an impurity of Freon 218 agree with calculated data.

High purification of nitrous oxide by distillation

A method of the high purification of nitrous oxide from nitrogen and oxygen impurities by distillation at a high pressure was proposed. The effective separation coefficients for nitrous oxide—impurity systems have been found experimentally. The distillation process at high pressure was investigated. The dependences of the separation coefficient on the pressure were obtained. The optimal operating regime was investigated

Gases high purification from unreadily permeating impurities in one-compressor multistage membrane apparatuses

The present work is focused on gases high purification from unreadily permeating impurities by one-compressor multistage membrane apparatus (OMMA). It looks like a simple one way membrane cascade, consisting from several membrane modules with only one compressing point. In this operating regime the pressure of high pressure cavity is decreasing from one to another while the concentration of high penetrating component is increasing. The equation of purification degree calculation was obtained. It shows how the impurity concentration of permeate reduces in comparison with initial concentration of flow (feed flow), incoming to the membrane module or apparatus. The equation for purification degree calculation was obtained. For the case of low impurity concentration there was leaded the comparison of calculated and experimental (from patent) data. The dependence of purification degree on the number of membrane modules composed apparatus which has an extremum was shown.The description of one-compressor multistage membrane apparatus was determined. The equation of purification degree calculation was obtained. It shows how the impurity concentration of permeate reduces in comparison with initial concentration of flow (feed flow), incoming to the membrane module or apparatus. The equation for purification degree calculation was obtained. For the case of low impurity concentration there was leaded the comparison of calculated and experimental (from patent) data. The dependence of purification degree on the number of membrane modules composed apparatus was shown.