Heterogeneous Azeotropic Distillation Process Research Articles

Fabrication of alumina nanofibers by precipitation reaction combined with heterogeneous azeotropic distillation process

γ-Alumina nanofibers have been prepared from a precipitation reaction between aluminum ammonium sulfate and Baker's salt solutions followed by a heterogeneous azeotropic distillation process with N-butanol and calcination at 1173 K. Experimental results indicate that the terminal pH value of the reaction mixture should be kept at 7.00–8.00 in order to obtain γ-Al 2O 3 nanofibers. The resulting spherical aluminum hydrate precipitates are evolved into two-dimensional crystallized pseudoboehmite lamellae after the heterogeneous azeotropic distillation and then transformed into γ-Al 2O 3 nanofibers with ca. 3–5 nm thick and 50–150 nm long after further calcination at 1173 K. The formation of γ-Al 2O 3 nanofibers can attribute to the preferential growth along the longitudinal axis due to the inherent instability of the planar structure of the pseudoboehmite during the calcination process.

Heterogeneous extractive batch distillation of chloroform–methanol–water: Feasibility and experiments

A novel heterogeneous extractive distillation process is considered for separating the azeotropic mixture chloroform–methanol in a batch rectifying column, including for the first time an experimental validation of the process. Heterogeneous heavy entrainer water is selected inducing an unstable ternary heteroazeotrope and a saddle binary heteroazeotrope with chloroform (ternary diagram class 2.1-2b). Unlike the well-known heterogeneous azeotropic distillation process and thanks to continuous water feeding at the column top, the saddle binary heteroazeotrope chloroform–water is obtained at the column top, condensed and further split into the liquid–liquid decanter where the chloroform-rich phase is drawn as distillate. First, feasibility analysis is carried out by using a simplified differential model in the extractive section for determining the proper range of the entrainer flowrate and the reflux ratio. The operating conditions and reflux policy are validated by rigorous simulation with ProSim Batch Column ® where technical features of a bench scale distillation column have been described. Six reproducible experiments are run in the bench scale column matching the simulated operating conditions with two sequentially increasing reflux ratio values. Simulation and experiments agree well. With an average molar purity higher than 99%, more than 85% of recovery yield was obtained for chloroform and methanol.

Column configurations of continuous heterogeneous extractive distillation

AbstractIncreasing regulations and constraints have renewed interest for more efficient distillation process in separating azeotropic mixtures and close boiling components. We investigate the feasibility of heterogeneous extractive distillation process in a continuous column considering several feed point strategies for the entrainer recycle stream and for the main azeotropic feed. Depending on these choices, the heterogeneous distillation column is composed of one, two, or three column sections. A differential mass balance model enables to compute continuous liquid composition profiles of the rectifying, extractive, and stripping sections. Unlike homogeneous extractive distillation, reflux policy composed by a single or both decanted liquid phases is considered as well as the external feeding influence on the composition of the top column liquid stream. Limiting operating conditions of key parameters like the entrainer/feed flowrate ratio and reflux ratio required to obtain a target top and bottom product compositions are obtained. For illustration, separation of acetonitrile–water mixture using butyl acetate as a heavy heterogeneous entrainer is selected. In this case, withdrawal of a saddle binary heteroazeotrope is the main difference of this process compared with the well‐known heterogeneous azeotropic distillation process where the top vapor product is the lower boiling point of the ternary system. © 2007 American Institute of Chemical Engineers AIChE J, 2007

Surface Modification of Al<sub>2</sub>O<sub>3</sub> Fine Powders and Application in Epoxy Resin

In this paper the surfaces of Al2O3 fine powders with average size of 500nm were modified by heterogeneous azeotropic distillation process. IR spectrums of the powders show that the distillation can effectively dehydrate hydrous Al2O3 powders, and succeed in substituting the hydrate water with butanol molecular. The dispersion of Al2O3 powders in epoxy resin is improved remarkably, which is observed by means of SEM. Experimental results show that abrasion property of the resin filled with modified Al2O3 powders is improved.

Separation of tert‐Butyl Alcohol‐Water Mixtures by a Heterogeneous Azeotropic Batch Distillation Process

AbstractTert‐butyl alcohol and water form an azeotrope at normal pressure. Simple distillation cannot be used to separate these two components. In this article, a systematic study of the separation of tert‐butyl alcohol–water mixtures with an entrainer by heterogeneous azeotropic batch distillation was performed. Based upon the thermodynamic behavior of the ternary mixtures, cyclohexane was chosen as the entrainer. It formed ternary and binary heterogeneous azeotropes with the original components. The process feasibility analysis was validated by using rigorous simulation with chemical process simulation software – HYSYS Plant 2.2 and DISTIL 4.1. Simulation results were then corroborated in a batch experimental column for the selected entrainer.

Simulation and optimization of heterogeneous azeotropic distillation process with a rate-based model

A rate-based simulation method for sieve tray columns is developed with the correlations of clear liquid height and mass transfer rate that were obtained in our previous experiments of the homogeneous and heterogeneous ternary distillation with a sieve tray column. The simulation method is applied to an ethanol dehydration process that consists of a dehydration column and an entrainer recovery column. In the simulation study, the effects of tray specification, overhead vapor concentration, locations of main feed and recycle flow, reflux ratio and recycle flow rate on separation performance of the columns are investigated. The simulation results show that increase of the reflux ratio and recycle flow rate decreases the necessary number of trays of the dehydration column to achieve a specified separation, but it increases the heat duties of the process. Then, the economical analysis of the process is carried out, and the optimum operation conditions of the process are discussed.

US municipal wastewater projects exceed 2000

The mixture of propylene glycol methyl ether and water form a minimum-boiling azeotrope. To separate the binary azeotropic system, energy-saving liquid–liquid extraction combined with either heterogeneous azeotropic distillation or extractive distillation processes based upon traditional two-column heterogeneous azeotropic distillation and three-column extractive distillation processes were proposed, using chloroform and 2-ethylhexanoic acid as solvents, respectively. The minimum total annual cost (TAC), based on a sequential iterative optimization procedure, and CO2 emissions for the two processes were determined. Liquid–liquid extraction combined with heterogeneous azeotropic distillation process achieved significant reductions of 40.24% in the TAC and 45.37% in CO2 emissions compared with the traditional two-column heterogeneous azeotropic distillation process. The liquid–liquid extraction combined with extractive distillation process achieved TAC and CO2 emission reductions of 34.18% and 43.95%, respectively, compared with the traditional three-column extractive distillation process. Thus, the two processes are more attractive in terms of both economics and environmental protection.

Preparation and characterization of nanoscale Y-TZP powder by heterogeneous azeotropic distillation

A heterogeneous azeotropic distillation process was effectively used to dehydrate hydrous zirconia and therefore prevent the formation of hard agglomerates in the preparation of nanoscale zirconia powder. The mechanism of azeotropic distillation to prevent hard agglomerate from forming was studied by investigating the interaction of hydrous zirconia with n-butanol. The prepared powder was sintered to 99.5% of theoretical density by slow-sintering (average grain size of ∼200 nm), 97.5% by fast-sintering (average grain size of ∼120 nm) at 1250°C.