Extractive Rectification Research Articles

Study of the composition of the KCl – AlCl<sub>3</sub> – ZrCl<sub>4</sub> – HfCl<sub>4</sub> melt in relation to extractive rectification of zirconium and hafnium chlorides

In 2021, Chepetsk Mechanical Plant SC put into operation the production of a zirconium sponge of nuclear purity for the production of nuclear fuel components. The purification of zirconium from hafnium is carried out by extractive rectification in a KCl–AlCl3 melt. The experience of the plant operation has shown that the elemental analysis of the melt for the content of K, Al, Zr, Hf is not enough to determine its operational properties. During the operation of the plant at various points of the technological scheme, the composition of the melt KCl–AlCl3–ZrCl4–HfCl4 was studied by a complex of independent methods using specially developed methods. The content of the phases ZrCl4, K2ZrCl6 and AlCl3 against the background of the matrix phase KAlCl4 was studied in frozen melts by X-ray diffractometry. The regularities of changes in the content of ZrCl4, AlCl3 and K2ZrCl6 according to the technological scheme of the installation are established. The content of the X-ray amorphous component, which contains up to 1.5 wt% aluminum and up to 3.5 wt% zirconium, has been established in frozen melts. By the method of reducing melting in the presence of carbon in frozen melts, the oxygen content of up to 1.8 wt% was determined, which is part of the X-ray amorphous component, presumably consisting of AlOCl and ZrOCl2. A method for determining the AlCl3/KCl ratio based on the difference in the physicochemical properties of the melt components has been developed. Based on the results obtained, the melt composition was adjusted during the operation of the zirconium and hafnium chloride separation unit at ChMP JSC.

Purification of Phenol and Chloroform from Impurity Components by Extractive Rectification

Purification of Phenol and Chloroform from Impurity Components by Extractive Rectification

Efficiency of Heat Pumps in Extractive Rectification of the Allyl Alcohol–Allyl Acetate Mixture with Different Compositions of the Feed: Part 1. Application of Heat Pumps in Schemes with Two-Selection Columns

Efficiency of Heat Pumps in Extractive Rectification of the Allyl Alcohol–Allyl Acetate Mixture with Different Compositions of the Feed: Part 1. Application of Heat Pumps in Schemes with Two-Selection Columns

Alcohol Dehydration by Extractive Distillation with Use of Aminoethers of Boric Acid

Aminoethers of boric acid (AEBA) were studied as potential extractants for the separation of aqueous–alcoholic azeotropic mixtures by extractive distillation. The conditions of vapor–liquid equilibrium in aqueous solutions of ethanol and isopropanol in the presence of AEBA were studied. The division of AEBA molecules into group components was proposed, and previously unknown geometric parameters of the boron group and the energetic pair parameters of the boron group with the alkane group, ether group, amine-3d group, and alcohol group were determined within the framework of the Universal Functional Group Activity Coefficient (UNIFAC) model. The modeling of the extractive rectification process of an ethanol–water mixture with AEBA as extractant has been carried out. The dependences of the cost function on the extractant flow rate, the residual water content in it and the number of theoretical trays were obtained. A technological scheme for ethanol dehydration has been proposed, and its technological characteristics have been calculated.

Comparative Analysis of Separation Schemes of Reaction Mixtures of Epichlorohydrin Production in the Presence of Various Solvents

On the basis of a thermodynamic–topological analysis of phase equilibrium diagrams of reaction mixtures formed during the liquid phase epoxidation of allyl chloride with an aqueous solution of hydrogen peroxide in an organic solvent in the presence of a heterogeneous catalyst, two principal technological separation schemes are proposed. Two lower alcohols are considered as solvents: methanol and propanol-2. Both schemes are aimed at the isolation of all components in pure form and are based on the use of special separation methods: extractive rectification with dimethyl sulfoxide (separation of allyl chloride–methanol and propanol-2–water component pairs) and a combination of rectification and delamination (separation of binary allyl chloride–water and water mixtures–epichlorohydrin). The material balances of separation schemes for mixtures of a specific composition are calculated (one composition for both mixtures is considered). To determine the operation parameters of rectification columns (the number of separation stages, feed plate, and reflux ratio), a computational experiment is conducted using the Aspen Plus® software. Preference is given to parameters ensuring the production of all substances with a purity that meets GOST (State Standard) with minimum energy consumption. The separation scheme of the mixture with propanol-2 containing one column less is characterized by a lower total number of separation stages (by 32 theoretical plates) and lower (by 11%) energy consumption compared to the separation scheme of the mixture with methanol. In addition, the epoxidation reaction with an excess of propanol-2 (the alcohol concentration should be at least 68 wt %) can significantly simplify the allocation of the target product of epichlorohydrin, which is impossible for a system with methanol.

RESEARCH OF VARIOUS ISO-MANIFOLDS IN FOUR COMPONENT SYSTEMS CONTAINING BIAZEOTROPIC BINARY CONSTITUENTS

In the present work, an analysis of the mutual arrangement of a number of iso-manifolds in the concentration tetrahedron formed by the components of the separated mixture and an additional substance, an extractive agent, was carried out to estimate the possibility of separating three-component mixtures containing biazeotropic constituents by extractive rectification. The objects of research were four-component systems formed by ternary constituents (butyl propionate (BP) - propionic acid (PA) - butyl butyrate (BB), butyl propionate - propionic acid - butyric acid (BA), butyl butyrate - butyric acid -butyl propionate, butyl butyrate - butyric acid -propionic acid) of the commercially important BP-PA-BB-BA system, and the extractive agent sulfolane. Using the results of the computational experiment based on mathematical model NRTL-HOC we obtained complete data on the vapor-liquid equilibrium in binary, three- and four-component systems. The structures of liquid-vapor phase diagrams were obtained, and thermodynamic-topological analysis of all four-component systems was carried out. The mutual arrangement in the concentration tetrahedron of manifolds of relative volatility (equal to 1) of the components, reflecting the evolution of pseudo-azeotropes in sections with a constant concentration of the extractive agent; pseudo-ideal manifolds along which the activity coefficients of the components of the base (separated) mixture are equal to each other; isothermo-isobaric manifolds generated by Bancroft points in binary azeotropic constituents were determined. We established that it is possible to separate the studied three-component mixtures by extractive rectification using sulfolane.

Thiophene extraction from the gasoline fraction of LTC shale tar

The composition of narrow fractions of shale gasoline extracted from LTC (low-temperature carbonization) tar is determined by rectification and gas chromatography–mass spectrometry. The LTC tar is derived from high-sulfur Mishor Rotem shale. The fractions considered are <77°C, 77–85°C, 85–105°C, 105–115°C, 115–130°C, and 130–150°C. The selective extractants N,N-dimethylformamide and N-methylpyrrolidone are used in extractive rectification of the gasoline, toluene, and xylene fractions of the LTC shale tar. The material balances are determined, and the composition of the distillates and bottoms obtained are determined. The results show that it is possible, in principle, to extract thiophene and its homologs from these fractions by extractive rectification using selective extractants.

Mathematical modeling of extractive rectification of a butyl butyrate–butyric acid mixture

The extractive rectification of a butyl butyrate–butyric acid mixture under reduced and atmospheric pressures has been studied by mathematical simulation using the Aspen Plus® v.8.0 software package. It has been shown that, from an energy point of view, extractive rectification of a butyl butyrate–butyric acid mixture should be performed under reduced pressure (e.g., 140 mm Hg) when this mixture is biazeotropic, rather than under atmospheric pressure when the system is zeotropic.

Ionic liquids as separating agents in extractive rectification

This article presents extractive rectification of binary mixtures. The choice of extractive agents was made from a set of well-known separating agents with ionic liquids. Gas–liquid chromatography was used to estimate the separating agent selectivity. Vapour–liquid equilibrium mathematical modelling was used to predict the quality of the product. The applicability of ionic liquids in extractive rectification of different binary azeotropic mixtures (both positive and negative azeotropes) was proved by laboratory experiments and computer simulations. Experimental conditions, parameters of rectification column and the separation results are presented.

Synergetic effect of binary separating agents in extractive rectification of homogeneous mixtures

Possibility of the use of dimethylsulfoxide-ethylene glycol binary separating agent for extractive rectification of ethanol-water and acetone-chloroform azeotropic mixtures has been considered. In both cases, the synergetic effect of binary separating agent has been detected. Upon the extractive rectification of the acetone-chloroform mixture, the assumption of a synergetic effect provides lower energy consumption upon separation compared to individual separating agents.

Sulfolane and dimethyl sulfoxide as extractants

The use of sulfolane and dimethyl sulfoxide in liquid extraction and extractive rectification is considered.

Development of processes for C4 hydrocarbons separation and 1,3-butadiene purification

Physicochemical substantiation and improved more effective technologies for C4-hydrocarbons separation and 1,3-butadiene purification with the help of polar extragents are given, such as compressorless extractive rectification with the use of an intermediate desorbent, extractive rectification of the butane-n-butene fraction with preliminary isomerization of 1-butene into 2-butenes, the combined removal of -acetylenes C4 and methylallene by rectification with a small introduction of the extragent, and the hydration of butenyne in the C4 fraction and distillation of propyne from it.

Extractive rectification by means of sulfolane in chemical technology: A review

This review covers recent research on extractive rectification by means of sulfolane to isolate and purify organic components.

Extractive rectification of the benzene fraction of reformer naphtha using N-methylpyrrolidone-N-formylmorpholine mixtures

Extractive rectification of the benzene fraction of reformer naphtha was studied, and the relative fugacity coefficients of the heptane-benzene system in the presence of N-methylpyrrolidone-N-formylmorpholine mixtures of various compositions were determined. A synergistic effect was revealed for a mixed selective solvent containing 29–30 wt % iV-formylmorpholine, 68–69% N-methylpyrrolidone, and 2–3 wt % water.

Benzene separation from the benzene fraction of reformer naphtha by extractive rectification with N-methylpyrrolidone-sulfolane mixtures

Extractive rectification of the benzene fraction of reformer naphtha with N-methylpyrrolidone-sulfolane mixtures exhibiting synergistic effect was studied. After benzene separation, the distillate contains less than 1 vol% benzene and can be used as component of automobile gasolines.

Development and improvement of extraction processes for separation and purification of petroleum products

At present, more than 150 industrial installations for extraction of aromatic hydrocarbons with sulfolane from products formed in pyrolysis and catalytic reforming of gasoline fractions are in use in the world. About 9 million tons of benzene, toluene, and xylene is annually produced by extractive rectification (Morphylane) and extraction (Morphylex) with N-formylmorpholine on 55 industrial installations [1]. Mixtures of N-formylmorpholine and N-acetyl-morpholine are also used in the Morphysorb process for absorption purification of natural gas and industrial gases with high content of hydrogen sulfide and carbon dioxide [2]. The Sulfinol process is widely used for absorption of hydrogen sulfide and other sulfur-bearing compounds from hydrocarbon gases and hydrogen. This process employs a mixed absorbent composed of a chemisorbent (diisopropanolamine), water, and sulfolane as a physical solvent [3].

Extraction with monoethanolamine: A review

The production of monoethanolamine is considered, as well as its use as a separating agent in liquid extraction (and extractive rectification) for the production of pure organic compounds in the coke, oil, and chemical industries in Russia and around the world.

Heterogeneous systems of extractive rectification with one high-boiling component

The behavior of fold lines in the scalar fields of equilibrium temperatures and univolatility lines for the extractive rectification of azeotropic two-phase binary systems by one high-boiling agent is analyzed.

The special features of the phase behavior of multicomponent biazeotropic systems

A mathematical model of vapor-liquid equilibrium was obtained for the benzene-pefluorobenzene-methyl propionate-dimethylsulfoxide system. The phase behavior of the ternary biazeotropic constituent over the sections with a constant dimethylsulfoxide concentration was analyzed. The conditions of separation of the benzene-perfluorobenzene-methyl propionate three-component mixture was predicted. The result was substantiated by extractive rectification calculations in the presence of dimethylsulfoxide.

Using 2-pyrrolidone in liquid extraction and extractive rectification: A review

Using 2-pyrrolidone in liquid extraction and extractive rectification: A review