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Study of the LLE, VLE and VLLE of the Ternary System Water + 1-Butanol + Isoamyl Alcohol at 101.3 Kpa

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Study of the LLE, VLE and VLLE of the Ternary System Water + 1-Butanol + Isoamyl Alcohol at 101.3 Kpa View metadata, citation and similar papers at core.ac.uk brought to you by CORE Submitted to Journal of Chemical & Engineering Data provided by Repositorio Institucional de la Universidad de Alicante This document is confidential and is proprietary to the American Chemical Society and its authors. Do not copy or disclose without written permission. If you have received this item in error, notify the sender and delete all copies. Study of the LLE, VLE and VLLE of the ternary system water + 1-butanol + isoamyl alcohol at 101.3 kPa Journal: Journal of Chemical & Engineering Data Manuscript ID je-2018-00308r.R3 Manuscript Type: Article Date Submitted by the Author: 27-Aug-2018 Complete List of Authors: Saquete, María Dolores; Universitat d'Alacant, Chemical Engineering Font, Alicia; Universitat d'Alacant, Chemical Engineering Garcia-Cano, Jorge; Universitat d'Alacant, Chemical Engineering Blasco, Inmaculada; Universitat d'Alacant, Chemical Engineering ACS Paragon Plus Environment Page 1 of 21 Submitted to Journal of Chemical & Engineering Data 1 2 3 Study of the LLE, VLE and VLLE of the ternary system water + 4 1-butanol + isoamyl alcohol at 101.3 kPa 5 6 María Dolores Saquete, Alicia Font, Jorge García-Cano* and Inmaculada Blasco. 7 8 University of Alicante, P.O. Box 99, E-03080 Alicante, Spain 9 10 Abstract 11 12 In this work it has been determined experimentally the liquidliquid equilibrium of the 13 water + 1butanol + isoamyl alcohol system at 303.15K and 313.15K. The UNIQUAC, 14 NRTL and UNIFAC models have been employed to correlate and predict LLE and 15 16 compare them with the experimental data. Additionally, the vapor-liquid and vapor- 17 liquidliquid equilibria of this system have also been determined using a modified 18 Fischer labodest still. The data obtained have been used to correlate and obtain the 19 binary interaction parameters for UNIQUAC and NRTL. It has been analysed the 20 validity of the models to reproduce the VLE and VLLE data. 21 22 1. Introduction 23 24 The search for sustainable alternative fuels destined for use in industry has, in 25 general, been on the rise due to the growing concerns regarding: the future availability 26 of oil reserves; environmental problems (global warming and climate change) [1]; 27 increasing crude oil prices; the volatility of oil supply; and existing legislation that 28 29 restricts the use of nonrenewable energy sources and mandates the use of fuel from 30 renewable sources [2]. Several nonpetroleum based liquid biofuels obtained from 31 biomass may constitute viable alternatives. In this regard, alcohols such as methanol, 32 ethanol and butanol are competitive due to their advantageous physicochemical 33 properties. 34 35 Ethanol is the most widely used biofuel today, but it suffers from several 36 disadvantages that suggest it needs to be replaced. The most important disadvantage 37 is that ethanol produces only about threequarters of the energy obtained from 38 conventional gasoline [3]. Butanol is seen as a potential alternative to ethanol because 39 40 it is less volatile and explosive, has a higher flash point, and lower vapour pressure, 41 which makes it safer to handle. It contains more energy, it is less hygroscopic and can 42 easily mix with gasoline in any proportion. In addition, butanol and gasoline have a 43 similar air to fuel ratio and energy content. Butanol can be used directly or blended with 44 gasoline or diesel without any vehicle retrofit and supplied through existing gasoline 45 pipelines [4]. 46 47 These second-generation biofuels are made from the inedible parts of 48 lignocellulosic biomass. The biobutanol production process involves pretreatment and 49 hydrolysis of raw material followed by fermentation of sugars to butanol. The principal 50 51 obstacle is the high production cost which includes: the capital investment and the cost 52 of equipment, raw materials, pre-treatment, the enzyme, strain development, recovery, 53 as well as the cost of R&D, sales and marketing of butanol. Nowadays, numerous 54 research groups are working on the cost contributing factors while also analysing the 55 R&D strategies and the latest technologies that will render the process practical and 56 costeffective [5]. 57 58 59 *Corresponding author. Tel.: +34 965903365. E-mail address: [email protected] (J. Garcia-Cano). 60 ACS Paragon Plus Environment Submitted to Journal of Chemical & Engineering Data Page 2 of 21 1 2 3 4 5 Biofuel purification is an important step in the overall production process as it 6 involves the separation of biobutanol from the undesirable impurities, water in 7 particular. During the production of biobutanol by fermentation, or obtained through 8 reaction with bioethanol as a feed, several other by-products appear as impurities 9 (such as pentanols) [6]. Our research group has been investigating the viability of using 10 hydrocarbons as entrainers in the dehydration of butanol [7, 8, 9]. Going further into the 11 research of obtaining a biofuel for use as an additive in conventional fuel, it is 12 13 necessary to not only separate the 1butanol from the water, but also to separate it 14 from the other impurities present in the reaction media. This, in turn, requires obtaining 15 experimental data for the liquidliquid, vapour-liquid and vapour-liquidliquid equilibria 16 (LLE, VLE, and VLLE, respectively) of these ternary systems. One of the impurities is 17 isoamyl alcohol. 18 19 In the present work, we report experimental VLE and VLLE data for the water + 20 1butanol + isoamyl alcohol ternary system at a constant pressure of 101.3 kPa, as 21 well as LLE data at different temperatures (303.15 and 313.15 K) and the same 22 pressure. We also discuss the accuracy with which the activity coefficient models can 23 24 predict these various equilibria. Only LLE data for this system have been published 25 previously in the literature [14]. 26 27 Water + 1butanol + isoamyl alcohol is a type 2 heterogeneous ternary system 28 with two partially miscible pairs: water + 1butanol and water + isoamyl alcohol. It has 29 two binary heterogeneous azeotropes, water + 1butanol and water + isoamyl alcohol 30 [10]. 31 32 2. Experimental 33 34 2.1 Chemicals 35 36 Specifications for all chemical compounds used in the experiments are provided 37 in Table 1. Ethanol (used as internal standard), 1-butanol and isoamyl alcohol were 38 used as supplied by the provider without further purification. Ultrapure water was 39 obtained using a Mili-Q Plus system. The Karl-Fisher titration method was used to 40 determine the water content of the chemicals. 41 42 Table 1. Chemicals employed in this work. 43 44 Chemical Provider Initial purity (mass fraction) water content (mass fraction) Purification method Analysis method 45 a 46 1-butanol Merck >0.995 ≤0.001 None GC 47 Isoamyl alcohol Merck >0.990 ≤0.002 None GCa 48 Ethanol Merck >0.999 <0.001 None GCa 49 a GC, Gas Chromatography 50 51 52 53 2.2 Experimental procedure 54 55 2.2.1 LLE data determination 56 57 58 59 60 ACS Paragon Plus Environment Page 3 of 21 Submitted to Journal of Chemical & Engineering Data 1 2 3 Mixtures of known overall composition belonging to the heterogeneous region were 4 prepared in glass tubes and sealed with screw caps and Teflon septum. These tubes 5 were submerged partially inside a thermostatic bath maintained at a constant and 6 controlled temperature. They were also shaken vigorously to speed up equilibration. 7 Afterwards, the tubes were left in the bath at the same temperature in order to permit 8 decantation and promote phase separation. The bath temperature was 303.15 K in one 9 10 of the experiments and 313.15K in the other. 11 After the phase separation, weighed samples were extracted from both layers by 12 13 means of syringes and injected into vials. A measured amount of ethanol was added in 14 each of the vials as an internal standard for quantification purposes and to avoid phase 15 splitting when the samples began to cool down outside of the thermostatic bath. An 16 additional sample was taken from each of the organic layers and their water content 17 was checked against the Karl Fischer technique. The Water content determined by the 18 Karl Fischer titration is used to verify the value obtained from the chromatography. 19 20 Each of the vials were analysed by gas chromatography. The organic phases were 21 analysed in a Shimadzu GC14 with a Porapak Q packed column and a thermal 22 conductivity detector (TCD). The oven temperature was set to 463 K, the injector to 23 24 483 K, and the TCD to 483 K. The current was fixed at 100 mA. The carrier gas, 25 helium, was supplied at a flow rate of 30 mL/min. 26 27 The aqueous phases were analysed by means of an Agilent 7820A chromatograph. In 28 both GC systems the same chromatographic phase (Porapak Q) was used. A TCD and 29 a Flame Ionisation Detector (FID) were placed in series just after the column. The 30 helium flow rate was 20 mL/min. The temperatures were 503, 523, 523 and 523 K for 31 the oven, injector, TCD and FID. This chromatograph has been employed In order to 32 analyze the composition of the organic compounds in the aqueous phase whose 33 34 concentrations are low. It possesses not only a TCD but it also has a FID. The FID 35 being a more sensitive detector, it allows a better quantification of the organic 36 compounds. 37 38 In order to quantify the samples’ composition, standards of a known composition, and 39 with ethanol as internal standard, were prepared and analysed by the same procedure 40 used on the samples.
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