BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS FACULTY OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY GEORGE OLÁH DOCTORAL SCHOOL Vapor-Liquid Equilibrium Studies on Bio-oxygenate Liquid Mixtures Thesis booklet Author: Munaf Al-Lami Supervisor: Prof. Dr. László T. MIKA Consultant: Dr. Dávid HAVASI Department of Chemical and Environmental Process Engineering Budapest University of Technology and Economics Catalysis Research Group Budapest 2023 1 Introduction and literature review The global transition towards a more sustainable economy is driving the demand for renewable and environmentally friendly chemicals. Among the various classes of renewable chemicals, biomass platform chemicals have emerged as a promising alternative to petroleum-based chemicals. Biomass platform chemicals are derived from lignocellulosic materials, which are abundant and renewable feedstocks. The availability of expanded usage of renewable energy is contingent upon advancements in technology, long-term planning, realization of integration strategies, and enough expenditure. Biomass resources can be converted into fuels and energy barriers (e.g. ethanol, bioethanol, methane, methanol, dimethyl ether, and hydrogen) by using suitable thermal or biochemical conversion technologies.1 Knowledge of the many types of bioenergy, the different kinds of biomass materials and where they come from, and the multiple types by-products coming from converting biomass resources is essential for grasping the full breadth of bioenergy. Bioenergy feedstocks typically come from three distinct forms of biomass: sugars/starches, lipids, and cellulose/lignocellulose. The first generation of biofuels is derived from the sugars and starches present in food crops like corn grain. Fats, oils, and waxes are all examples of lipids, which are energy-dense, waterinsoluble molecules. Animal fats, vegetable oils, and algal lipids are all potential feedstocks. Several common seed crops are used to produce oils for biodiesel, including soybeans, oil palms, and sunflowers. Cellulosic/lignocellulosic biomass is made up of complicated carbohydrates and non-carbohydrate compounds present in plants' leaves and stems. Cellulose/lignocellulose has little or no nutritional benefit in humans. As a result, advanced biofuels provide a chance to utilize these remarkably low resources in the production of valuable energy products.2 One of the most promising classes of biofuels is bio-oxygenates, which are oxygencontaining compounds that are derived from renewable biological sources, such as plants, algae, or waste products. They have gained significant attention due to their potential as sustainable alternatives to traditional fossil fuel-based chemicals. Bio-oxygenates have various environmental benefits, including reduced greenhouse gas emissions and increased energy security. Among the bio-oxygenates, ๏ง-valerolactone, 2-methyltetrahydrofuran and 1,4-pentanediol are identified as promising materials due to their renewable nature and 1 potential as sustainable alternatives to traditional fossil fuels. They have a wide range of applications in various industries, including biofuels, solvents, and precursors for the production of biodegradable polymers and plastics.3 The production of bio-oxygenates including GVL, 1,4-PDO, and 2-MeTHF from levulinic acid often results in a mixture of these compounds.7 These mixtures have distinct properties and behaviors that can greatly influence their potential uses in different industries. Therefore, it is critical to study and investigate these mixtures to gain a comprehensive understanding of their properties and potential applications including efficient product.3 To understand the thermodynamic behavior of bio-oxygenate liquid mixtures, it is important to measure the vapor-liquid equilibrium (VLE) and obtain the binary interaction parameters. VLE is a crucial parameter in the design and optimization of separation processes and plays an essential role in understanding the physical and chemical properties of the mixture. Measuring the VLE data of bio-oxygenate liquid mixtures can provide insight into their thermodynamic behavior and help to optimize the production process. Obtaining the binary interaction parameters can enable the development of predictive models, which can be used to estimate the thermodynamic properties of bio-oxygenate mixtures. These models can be particularly useful in the absence of experimental data and can significantly reduce the time and cost required for the design and optimization of separation processes. Therefore, understanding the VLE behavior of bio-oxygenate liquid mixtures and obtaining the binary interaction parameters is critical for the efficient and sustainable production of biofuels. 2 Experimental work The modified Gillespie still, redesigned by Havasi4 in 2016, was used to perform the the vapor-liquid equilibrium experiments. The still was connected to a pressure regulation system via the top condensers. The temperature-dependent vapor pressure measurements were conducted for five compounds: GVL, 2-MeTHF, THF, toluene, and 1,4-PDO. The VLE experiments were performed under different pressures for six mixtures containing the bio-oxygenate, GVL, or 1,4-PDO. The analysis of the samples was performed by employing the refractometer and gas chromatography (GC). The data were further treated using ChemCad Aspen Plus software. 2 To analysis and measure the refractive indices, both type G Carl Zeiss Abbe refractometer (with an integrated thermostat, and A670 auto digital refractometer, which has a CCD light-sensitive part based on the Abbe principle were utilized. Also, due to the lack of data regarding the refractive indices of pure 1,4-PDO in the literature, the refractive indices of the corresponding chemical were measured at different temperatures. Some samples were also tested using gas chromatography and 1H NMR to verify the accuracy of the refractometry results, where no significant differences were identified, which gave validity to the refractometer to be used for the analysis of the samples. The VLE samples from these mixtures were analyzed using HP 6890N chromatography apparatus, which was run in a splitless configuration, using H2 as the carrier gas, and an HP INNOWax capillary column (15 m × 0.25 μm × 0.25 μm) fitted with an FID detector. The analyses were performed using 10 mL of VLE sample dissolved in 1 mL of dichloromethane and took advantage of toluene as an internal standard. In addition, a Bruker Avance-250 NMR spectrometer was used to confirm the purity of the used material. Deuterated chloroform was used to dissolve the materials, and benzene was used as a standard. A rolling ball viscometer (Lovis 2000, Anton Paar) was used to measure the viscosity of 1,4-PDO at an angle of 70 degrees. Capillary and ball diameters were 1.8 and 1.5 mm, respectively. Anton Paar DMA 4500 M apparatus was employed to measure the densities. The viscometer and the densimeter were calibrated using water. 2.1 Vapor pressure measurement Knowledge of the vapor pressure for the applied chemicals is essential for the calculation of the activity coefficients. For that reason, Antoine's adjustable parameters are required for the investigated materials. The temperature-dependent vapor pressure of the GVL, THF, 2-MeTHF, toluene, and 1,4-PDO were experimentally determined employing the equilibrium still The modified Gillespie still, redesigned by Havasi4. The vapor pressure of the examined materials was experimentally measured in the equilibrium still to guarantee that the results are based on data provided for the relevant temperature range. The measurements started by filling the still with pure substance. Pressures of different values were applied to the system during the measurement process, and once the temperature had stabilized, the corresponding pressure and temperature pairs were recorded. The three 3 adjustable parameters of the Antoine equation were obtained using those pairs by employing the Excel solver function. 3 Results and discussion 3.1 Vapor pressure measurements The temperature-dependent vapor pressure of GVL, 2-MeTHF, THF, toluene, and 1,4-PDO were experimentally measured at the specified range, and the results were regressed with the Antoine equation. The adjustable parameters of the corresponding equation were obtained using Excel Solver and presented in Table1. For the all measured vapor pressure data the consistency were tested using the Oonk method,5,6 the results are presented in Figure 1. Table1: Antoine parameters for the materials investigated at the specified temperature range. chemical temperature range /K GVL 377.85 – 480.55 2-MeTHF 296.70 − 353.30 THF 302.00 – 339.25 Toluene 321.27 − 383.45 1,4-PDO 413.10 − 496.50 A B C 6.4314 ± 1888.0173 ± –53.9478 0.0291 22.8921 2.3781 5.15780 ± 761.7718 ± −111.7206 0.0614 27.3455 3.9526 5.2177 ± 747.0081± -106.8035 0.0427 23.2826 2.8213 5.3778 ± 922.3461 ± 110.0198 0.0385 19.6080 2.6790 5.8942 ± 1210.9794 ± −185.0325 0.0604 34.0884 3.8818 4 ± ± ± ± ± Figure 1: Oonk consistency test. 3.2 Heat of vaporization Using the pressure-temperature pairs that were obtained experimentally, the heat of g,id vaporization (โl 0 ๐ปm / kJ·mol–1) for the studied material was computed, in which the data were regressed using the Calusius −Clapeyron equation, by assuming the gas phase to g,id behave ideally, where โl 0 ๐ปm / J·mol–1 is a heat of vaporization for an ideal system, R = 8.314462 J·K–1·mol–1 is the molar gas constant, T / K is temperature, and po / kPa is vapor pressure. g,id โl 0 ๐ปm = dln(๐0 /kPa) ๐ (๐/K)2 d(๐/K) 5 (1) g 0 โl ๐บm ๐0 1 1 ๐ 0 (๐) ( − ) ๐ ln ( ๐ ) = − + โl ๐ปm ๐ ๐ ๐ ๐ (2) ๐ ๐ ๐ 0 (๐) [( ) − 1 + ln ( )] + โ๐ ๐ถ๐,m ๐ ๐ Furthermore, the Clarke–Glew relation,7 g 0 eq (2), where โl ๐ปm / J·mol–1 is the g 0 enthalpy of vaporization at a reference temperature (๏ฑ ), โl ๐บm / J·mol–1 is the variation in molar Gibbs energy between the liquid and the gas phase at a reference pressure (the gaseous phase is supposed to have characteristics of an ideal gas at the pressure ps), and g 0 โl ๐ถ๐,m / J·mol–1·K–1 is the variation between the heat capacities of the ideal gas and the condensed phase. The regression was applied with a ps = 105 Pa and a ๏ฑ = ๏ฒ๏น๏ธ๏ฎ๏ฑ๏ต ๏ as a reference pressure and temperature, respectively, to calculate the corresponding thermodynamic parameters of the investigated chemicals, which are shown in Table 2. Table 2: Parameters of Clausius−Clapeyron and Clarke−Glew equations Reference temperature ๏ฑ = ๏ฒ๏น๏ธ๏ฎ๏ฑ๏ต ๏ and Pressure Ps material g,id Tmin – Tmax โl /K / kJ·mol–1 = 105 Pa 0 ๐ปm g 0 โl ๐ปm kJ·mol–1 GVL 2-MeTHF THF 377.85 – 47.43 480.55 0.12 296.7 353.3 302.0 339.3 321.27− Toluene 1,4-PDO – – ± g g 0 โl ๐ถ๐,m / 0 / โl ๐บm / kJ·mol–1 J·mol–1·K–1 51.51 ± 0.14 35.76 ± 0.02 -31.86 ± 1.10 33.9 ± 0.2 37.0 ± 0.2 5.343 ± 0.005 –112.83 ± 5.46 32.1 ± 0.2 34.6 ± 0.8 3.963 ± 0.003 –105.13 ± 3.62 37.31 ± 42.72 ± 0.19 383.45 0.21 413.10 − 66.42 ± 95. 496.50 1.14 1.89 61 6 ± 8.6815 0.0146 49. 16 ± 0.40 ± –97.06 ± 3.04 –187.41 ± 12.1 3.3 Refractive indices, density, and viscosity of 1,4-PDO Due to the limited number of reported data regarding the refractive index of 1,4- PDO,8,9 and the fact that some of those data showed large differences even when held at the same temperature, the refractive indices were determined across the range of 291.2– 333.2 K (Figure 2). Using eq (3), we found a highly significant linear relationship between the temperature and the refractive index (R2 = 0.993). ๐/K ๐๐ท = – 2.88285 × 10−4 โ ๐/K + 1.53154 (3) Figure 2: The temperature-refractive index for 1,4-PDO. Blue • : experimentally determined data series, blue – regressed linear equation, red โ and green โฒ: literature data.9 Since there is no density information for 1,4-PDO at the National Institute of Standards and Technology (NIST), we measured its temperature-dependent density from 293.1 to 363.1 K. The results are shown in Table 3, and they fall within the typical range for linear C5 diols. A linear correlation was used to describe the relationship between the data as shown in eq (4). ๐/g ⋅ cm−3 = – 6.5209 × 10−4 โ ๐/K + 1.17503 7 (4) Table 3: Density and viscosity for 1,4-PDO in 293.1–363.1 Ka at P = 101.3 kPa a T/K r / g⋅cm–3 h / mPa⋅s T/K r / g⋅cm–3 h / mPa⋅s 293.1 0.9833 243.867 333.1 0.9582 24.640 303.1 0.9773 124.967 343.1 0.9516 16.030 313.1 0.9710 69.067 353.1 0.9447 11.093 323.1 0.9647 39.883 363.1 0.9378 7.731 Standard uncertainties u are: u(T) = 0.1 K and u(r) = 0.0003 g⋅cm–3 and u(h) = 1 mPa⋅s. The temperature-dependent viscosity of 1,4-PDO was also determined in the range of 293.1 – 361.1 K, as viscosity is an important factor in heat transfer calculation and modeling. The results and regression analysis were determined using equations of the Arrhenius eq (5) and the Vogel-Fulcher-Tammann eq (6). The activation energy of viscous flow (Ea,h / kJ⋅mol–1) for 1,4-PDO was 47.55 kJ⋅mol–1 with a preexponential constant Ah = 8.15044⋅10–10 lnAh = –20.9278. The parameters of Vogel–Fulcher–Tammann equation are A = –5.2063 ± 0.2736, B = 1570.6375 ± 97.9622, T0 = 146.5395 ± 5.5228. ln ๐ = ๐ด๐ + ๐/mPa โ s = exp (๐ด + ๐ธ๐,๐ ๐ ๐ (5) ๐ต ) ๐/K − ๐0 / K (6) 8 3.4 Vapor-liquid equilibrium data The VLE data for the investigated mixtures were performed under isobaric conditions. The results were correlated using Wilson, NRTL and UNIQUAC models. The T-x-y diagrams are presented by Figure 3. Figure 3: T-x-y diagrams for the investigated mixtures. Experimental data (•, โ), green- - -: Raoult’s law calculations, black โฏโฏ: Wilson, black − − −: NRTL, black –––: UNIQUAC activity coefficient Models. 3.5 Regression of the experimental VLE date The gathered experimental vapor-liquid equilibrium data were correlated using three activity coefficient models; Wilson, NRTL, and UNIQUAC. The binary interaction parameters for the 2-MeTHF+GVL, THF+GVL and toluene+GVL systems were obtained using ChemCad software v.7.1 by employing the objective function given in eq(7). The software attained the interaction parameters for the necessary activity coefficient models using 138 iterations. The findings are presented in Table 4. 9 ๐ ๐ 2 ๐๐นChemCad = ∑ (๐calc. ;๐ − ๐exp ;๐ ) + ∑ (๐ฆcalc. ;๐ − ๐ฆexp. ;๐ ) ๐=1 2 (7) ๐=1 Since 1,4-Pentandeiol is not available in ChemCad database and because of the regression flexibility of the VLE data in Aspen Plus v.11 software, the latter was utilized to compute the BIPs for the 2-MeTHF+1,4-PDO and GVL+1,4-PDO mixtures. Aspen Plus also provided a better regression for the VLE of GVL+1,2-EDO mixture. The regression was performed using the maximum likelihood objective function of Britt Luecke,198 which is given by eq (8), where σ is the standard deviation of the indicated data, NP: the number of points in data group n, and NC is the number of components present in the data group. It is worth noting that the original form of the three activity coefficients models has been extended with extra parameters which offer more flexibility in the phase equilibrium fitting. The regression results are collected in Table 4. ๐๐ ๐calc − ๐meas 2 ๐calc − ๐meas 2 ) +( ) ๐๐นAspen = ∑ [( ๐๐ ๐๐ ๐=1 ๐๐ถ−1 2 (8) ๐๐ถ−1 2 ๐ฅcalc − ๐ฅmeas ๐ฆcalc − ๐ฆmeas ) + ∑ ( + ∑ ( ) ] ๐๐ฅ ๐๐ฆ ๐=1 ๐=1 Table 4: Binary interaction parameters (BIPs) obtained by ChemCad. system GVL+THF GVL+2MeTHF GVL+Toluen e Wilson Aij 230.403 3 NRTL Aji Bij - - 202.001 6.89709 1 3 - 63.8628 97.5906 63.8310 8 –416.07 1409.50 7583.80 0 0 UNIQUAC Bji αij 17.3670 0.300 2 4 153.347 0.316 202.573 2 3 4 – 280.280 0 10 0.300 0 ΔUij 76.5112 7 803.40 ΔUji 58.2168 8 134.097 3 –408.63 Table 5:Binary interaction parameters (BIPs) obtained by Aspen Plus. system model aij / – aji / – bij / K bji / K αij 2-MeTHF NRTL –1.8493 0.175955 1048.518 59.88137 0.3 + UNIQUAC 0.715366 –0.40617 –298.023 50.49299 - 1,4-PDO Wilson 0.257791 1.831978 -274.287 –1032.5 - GVL NRTL - - 527.017 -436.117 0.3 + UNIQUAC - - -316.198 247.458 - 1,4-PDO Wilson - - 366.989 -520.857 - GVL NRTL - - 578.828 123.307 0.3 + UNIQUAC - - -104.994 -131.532 - 1,2-EDO Wilson - -553.155 -217.515 - 4 - Practical applicability of the results The practical applicability of the results obtained from the measurements of VLE, vapor pressure, density, viscosity, and refractive index of bio-oxygenates liquid mixtures can be significant in various industries. Firstly, the knowledge of VLE is crucial in designing and optimizing various separation processes such as distillation, absorption, and extraction. Accurate data on VLE can help to determine the optimal operating conditions, choice of solvents, and overall behavior of the bio-based chemicals in mixtures, leading to more efficient and environmentally friendly processes. This can also result in a reduction in waste, energy consumption, and environmental impact, making the production and use of these chemicals more sustainable. Secondly, the vapor pressure data is crucial in understanding the thermodynamic properties of the substances, which can lead to process improvements and increased efficiency. The information obtained can also be used to predict the distribution of the components between the vapor and liquid phases, which is essential for the design and modeling of separation processes. Thirdly, the density and viscosity data are important in the design and optimization of fluid handling equipment and processes. Knowledge of these properties can help in selecting appropriate materials for pipelines, tanks, and reactors. It can also aid in the design of efficient mixing and agitation systems and the optimization of heat transfer processes. 11 Finally, the refractive index data is crucial in the development of quality control procedures and the determination of the purity of substances. The information obtained can also help to fill the gaps in knowledge and enhance the understanding of the behavior and characterization of these compounds. 5 Proposed theses 1. The binary systems of gamma-valerolactone (GVL) can be separated from tetrahydrofuran (THF), 2-methyltetrahydrofuran (MeTHF) or toluene by distillation as GVL-2-MeTHF, GVL-THF, toluene and GVL are non-azeotropic mixtures and deviate in a positive direction from Raoult's law across the entire concentration range at pressures of 101.3 and 50.7 kPa, indicating that intermolecular forces in the mixtures are weaker than in ideal liquid mixtures. Publication related to proposed thesis: MA4, MA3 2. The density and refractive index of 1,4-pentanediol are in a linear correlation with temperature in the ranges of 293.1–363.1 K and 291.2–333.2 K, respectively. Instead of the Arrhenius equation, the VFT equation should be used to calculate the temperaturedependent viscosity in the temperature range of 293.1– 361.1 K. Publication related to proposed thesis: MA2 4. The binary system of 2-MeTHF and 1,4-PDO is non-azeotropic mixture and it deviates in a positive direction from Raoult's law across the entire concentration range at pressures of 101.3 and 50.7 kPa. Publication related to proposed thesis: MA2 5. The binary system of GVL and 1,4-PDO is non-azeotropic mixtures and it deviates in a negative direction from Raoult's law across the entire concentration range at pressures of 50.7 and 10.1 kPa allowing straightforward distillation based separation. In the opposite, at 10.1 kPa, the binary system composed of GVL and 1,2-EDO forms a minimal the boiling point azeotropic mixture with an azeotropic composition in the mole fraction range of 0.55– 0.65. Publication related to proposed thesis: MA1 12 6 Publications and Lectures 6.1 Publications AM1. Al-Lami, M.; Pivarcsik, T.; Havasi, D.; Mika, L. T. Isobaric Vapor-Liquid Equilibria for Binary Mixtures of biomass-derived Gamma-Valerolactone + 1,4–Pentanediol and 1,2– Ethanediol. J. Chem. Eng. Data 2023. In press. (DOI:10.1021/acs.jced.2c00667)/ 90%; I.F (2021): 3.119/ (Q1). AM2. Al-Lami, M.; Szilágyi, A.; Havasi, D.; Mika, L. T. 1,4-Pentanediol: Vapor Pressure, Density, Viscosity, Refractive Index, and Its Isobaric Vapor-Liquid Equilibrium with 2Methyltetrahydrofurane. J. Chem. Eng. Data 2022, 67 (6), 1450–1459. (DOI:10.1021/acs.jced.2c00049)/ 100%; I.F (2021): 3.119/ (Q1), Independent citations: 1. AM3. Al-Lami, M.; Havasi, D.; Koczka, K.; Mika, L. T. Isobaric Vapor-Liquid Equilibria for Binary Mixtures of Gamma-Valerolactone + Toluene. J. Chem. Eng. Data 2021, 66 (1), 568–574. (DOI:10.1021/acs.jced.0c00791)/ 100%; I.F (2021): 3.119/ (Q1), Independent citations: 4. AM4. Al-Lami, M.; Havasi, D.; Batha, B.; Pusztai, É.; Mika, L. T. Isobaric Vapor–Liquid Equilibria for Binary Mixtures of Biomass-Derived γ-Valerolactone + Tetrahydrofuran and 2-Methyltetrahydrofuran. J. Chem. Eng. Data 2020, 65 (6), 3063–3071. (DOI: 10.1021/acs.jced.0c00084)/ 90%; I.F (2019): 2.49/ (Q1), Independent citations: 3. 6.2 Conference lectures 1. Al-Lami, M.; Mika, L. T. 1,4-Pentanediol: Preparation, characterization, and its phase equilibria with 2-methyltetrahydrofuran. Proceedings of the 48th International Conference of Slovak Society of Chemical Engineering, High Tatras, Slovakia. 25th May 2022. 2. Al-Lami, Mika, L. T. Separation studies on binary mixtures of biomass-derived γvalerolactone + toluene. 12th International Council of Environmental Engineering Education “Global Environmental Development & Sustainability: Research, Engineering & Management”. Online. 22 April 2021 3. Al-Lami, M.; Mika, L. T. Separation studies on binary mixtures of biomass-derived γvalerolactone + tetrahydrofuran and 2-methyltetrahydrofuran. 3rd George Olah Conference. BME, Budapest, Hungary; 28th September 2020. 13 References (1) Shuba, E. S.; Kifle, D. Microalgae to Biofuels: ‘Promising’ Alternative and Renewable Energy, Review. 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