Azeotropic Research Articles

Novel Process for Butyl Acetate Production via Membrane Reactor: A Comparative Study with the Conventional and Reactive Distillation Processes

Butyl acetate (BuAc) is widely used as a solvent in many applications, mainly in the food and pharmaceutical industries. The conventional process for BuAc production is both capital and energy intensive. The purification process involves the separation of BuAc from the azeotropic mixture of water and n-butanol, which is difficult to accomplish using a simple distillation unit. In this study, a membrane reactor (MR) for BuAc production via the esterification of n-butanol was investigated. The MR using the Amberlyst-15 catalyst was modeled and validated with previously reported experimental data, and a good agreement was achieved. The ultimate conversion of n-butanol using the MR was 92.0%, compared to 69.8% for the conventional reactor. This study is the first to propose an intensified MR-based process for butyl acetate production. The MR-based process was developed and rigorously simulated using Aspen Plus for an annual plant capacity of 92,500 metric tons of BuAc. The MR-based process is environmentally friendly regarding CO2 emissions, with a reduction of 80% compared to the conventional process. The economic analysis of the MR-based process shows a payback period of 2.7 years and a return on investment (ROI) of 23.1%. The MR-based process for BuAc production is a promising technology that provides similar key benefits as compared to the reactive distillation (RD) process.

Ionic liquids as entrainer in extractive distillation for effectively separating 1-propanol–water azeotropic mixture

Economically separating 1-propanol (NPA) from water is an emergent issue for producing pharmaceutical intermediates such as n-propyl acetate, n-propylamine and so on. In this work, fourionic liquids (ILs) 1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]), 1,3-dimethylimidazolium methylsulfate ([MMIM][MS]), 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) were introduced as potential entrainers for separating NPA–water azeotropic mixture. The results show that [MMIM][MS] is the most suitable entrainer compared with other ILs from the analysis of vapor–liquid equilibrium and relative volatilities. The extractive distillation process with the entrainer regeneration system of flash tank and stripper was employed and optimized by the two-step optimization method. The results show that total annual cost and energy consumption per product flow rate were reduced by 39.79% and 60.47% compared with literature. In addition, the efficiency indicator of extractive section, efficiency indicator of per tray in extractive section, carbon dioxide emissions were also selected as the evaluation index for selection of operating parameters and calculated for different cases. The CO2 emissions of the optimal design can be reduced by 60.98% from environmental aspect.

Design of novel side-stream hybrid reactive-extractive distillation for sustainable ternary separation of THF/ethanol/water using mixed entrainer

This work explored the possibility of using mixed entrainer in a hybrid reactive-extractive distillation to improve the sustainability of the recovery process for the ternary azeotropic mixture containing THF/ethanol/water. A double column reactive-extractive distillation (DCRED) using mixed entrainer (i.e. dimethyl sulfoxide (DMSO) + ethylene glycol (EG)) is initially proposed and intensified to a side-stream DCRED (SS-DCRED). Both the initial DCRED and SS-DCRED designs are optimised using particle swarm optimisation (PSO) to obtained optimum column configurations. The sustainability of the proposed processes using mixed entrainer are compared against pure EG as entrainer based on five different indicators, i.e. economic, environmental, safety, operational controllability, and thermodynamic efficiency. Generally, it was demonstrated that using mixed entrainer provides significant improvement in all sustainability indicators. Although there may be some trade-offs in the controllability and economic, such drawbacks are consistent with previous publications where the improvement in sustainability are always achieved at an expense of an increase in the economics. Overall, it was revealed that the optimised SS-DCRED using mixed entrainer provides the best improvement to the economic, controllability, safety, environmental, and thermodynamic efficiency by 21 %, 97 %, 19 %, 29 %, and 100 %, with respect to using pure entrainer, which reflects the sustainability of the proposed process.

N-octylpyridinium bromide applied to purification of benzene by extractive distillation: Thermodynamic properties for intuitive evaluation of entrainer

The N-octylpyridinium bromide ([Opy]Br) ionic liquid was subjected to thermodynamic properties studies, including those of activity coefficients at infinite dilution (γ12∞) and Flory–Huggins interaction parameters (χ12∞), to evaluate the interaction and solubility of [Opy]Br and solvents. [Opy]Br showed different separation potentials for three inseparable systems (benzene/ethanol, benzene/isopropanol, and benzene/thiophene), but no phase separation was observed when it was used as an entrainer for extractive distillation. Through the analysis of relative volatility curve, [Opy]Br can effectively separate benzene from benzene/ethanol and benzene/isopropanol azeotropic mixture, but it had no evident enhancement effect on benzene/thiophene. The results of separation performance were consistent with the analysis of selectivity (Sij∞) and capability (kj∞). Furthermore, an extractive distillation process was designed with Aspen Plus software to evaluate the competitiveness of [Opy]Br entrainer in the separation of benzene/ethanol. The results showed that [Opy]Br can be fully recycled without loss, which is more in line with the concept of green development than organic solvent entrainers.

Towards energy saving and carbon reduction of pressure-swing distillation for separating the ternary azeotropic mixtures by thermodynamic insights and process intensification

The recovery and separation of organic solvents such as tetrahydrofuran (THF), ethanol (EtOH), and methanol (MeOH) are important to protect the environment and save resources. Such ternary mixture has two azeotropes and one distillation boundary that makes separation difficult to be carried out using ordinary distillation technique. In this work, we developed a systematic approach for heat-integration (HI) and vapor recompression heat pump (VRHP) assisted triple-column pressure-swing distillation (TCPSD) for the recovery and separation of these valuable compounds. Firstly, the thermodynamics topological analysis is introduced to evaluate the feasibility of TCPSD for separating the ternary azeotropic mixture THF/EtOH/MeOH. Different separation sequence is determined via the combination of residue curve, component balance line, isovolatility curve, and distillation boundary. Subsequently, the potential application of HI and VRHP technologies is additionally explored for further minimizing the energy consumption and it is found that both process intensification technologies provide significant improvement in terms of economic, environmental impact, and energy efficiency. Relative to the traditional TCPSD, the application of VRHP technology to the TCPSD sequence B, in particular, provides 43.5% and 76.4% reduction in TAC and CO2 emission, respectively, while it improves the energy efficiency 100.4%.

Effect of choline lactate ionic liquid as entrainer on the thermodynamic properties of alcohols + water azeotropic mixtures

Ionic liquids could be used as entrainer in the azeotropic mixture separation process efficiently. Accordingly, the thermodynamic properties of ionic liquid choline lactate ([Ch][Lac]) as a potential entrainer have been studied in different azeotropic mixtures. In this respect, the density and speed of sound for binary systems containing (water + [Ch][Lac]) (ethanol/ 1-propanol/ 2-propanol) + [Ch][Lac])] and also ternary systems with different mass percent from alcohol-containing (water + alcohol + [Ch][Lac]) have been measured under a pressure 871 hPa at different temperatures T = (288.15 to 318.15) K. These data are used to calculate standard partial molar volume (Vφ0), and the limiting apparent molar compressibility (κφ0) using the Redlich-Mayer model besides the intermolecular free length (Lf) and relative association (RA) to interpret the existing interaction in the azeotropic mixture of the studied alcohols. Also, the scaled particle theory is used as a microscopic approach. All of the properties have been analyzed to interpret the interactions between the components of the mixture and 2-propanol has stronger interactions with the [Ch][Lac] in the azeotrope composition. The results suggest that the [Ch][Lac] could be used as an entrainer to separate 2-propanol more efficiently rather than the other studied alcohols.

Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures: Thermodynamic and Kinetic Modeling for Binary Adsorption of HFC-32 and HFC-125 on Zeolite 5A.

Hydrofluorocarbons (HFCs) have been used extensively as refrigerants over the past four decades; however, HFCs are currently being phased out due to large global warming potentials. As the next generation of hydrofluoroolefin refrigerants are phased in, action must be taken to responsibly and sustainably deal with the HFCs currently in circulation. Ideally, unused HFCs can be reclaimed and recycled; however, many HFCs in circulation are azeotropic or near-azeotropic mixtures and must be separated before recycling. Previously, pure gas isotherm data were presented for both HFC-125 (pentafluoroethane) and HFC-32 (difluoromethane) with zeolite 5A, and it was concluded that this zeolite could separate refrigerant R-410A (50/50 wt % HFC-125/HFC-32). To further investigate the separation capabilities of zeolite 5A, binary adsorption was measured for the same system using the Integral Mass Balance method. Zeolite 5A showed a selectivity of 9.6-10.9 for HFC-32 over the composition range of 25-75 mol % HFC-125. Adsorbed phase activity coefficients were calculated from binary adsorption data. The Spreading Pressure Dependent, modified nonrandom two-liquid, and modified Wilson activity coefficient models were fit to experimental data, and the resulting activity coefficient models were used in Real Adsorbed Solution Theory (RAST). RAST binary adsorption model predictions were compared with Ideal Adsorbed Solution Theory (IAST) predictions made using the Dual-Site Langmuir, Tóth, and Jensen and Seaton pure gas isotherm models. Both IAST and RAST yielded qualitatively accurate predictions; however, quantitative accuracy was greatly improved using RAST models. Diffusion behavior of HFC-125 and HFC-32 was also investigated by fitting the isothermal Fickian diffusion model to kinetic data. Molecular-level phenomena were investigated to understand both thermodynamic and kinetic behaviors.

Exploitation of distillation region diagrams for energy-efficient and cost-effective treatment of a hazardous effluent discharged from semi-conductor industries

The hazardous nature of certain azeotropic mixtures has urged the researchers to explore the separation techniques which can impart a contamination free environment. Despite of causing environmental concerns, these azeotropic mixtures are responsible for causing serious health issues to humans and animals. More specifically, in this article, we have taken Tetrahydrofuran (THF) - water azeotropic mixture into consideration. It has been reported that it affects the central nervous system, liver, as well as can cause carcinogenicity. To be more precise, in this article, two different entrainers has been evaluated on their merits of exploiting liquid-liquid phase envelope for separating Tetrahydrofuran-water binary azeotropic mixture. The process flow sheet schematic with n-octane as entrainer (having two distillation regions) has a reduced operating energy requirement by 21.11% while comparing with the Residue Curve Map of n-hexane as entrainer having three distillation regions. The total capital cost for THF-water-n-octane case has been found to be 7.1 $/y × 105 and that of THF-water-n-hexane case has been found to be 9 $/y × 105. However, in both of the cases, the product purity of 99.9% has been achieved for THF. Also, the classical trade-off between capital cost and energy cost has been shown in this study. The salient feature of this work is the use of dynamic simulation to understand the effect of recycle flow rate induced process operational in-feasibility due to distillation region shift.

Topology-Based Initialization for the Optimization-Based Design of Heteroazeotropic Distillation Processes

Distillation-based separation processes, such as extractive or heteroazeotropic distillation, present important processes for separating azeotropic mixtures in the chemical and biochemical industry. However, heteroazeotropic distillation has received much less attention than extractive distillation, which can be attributed to multiple reasons. The phase equilibrium calculations require a correct evaluation of phase stability, while the topology of the heterogeneous mixtures is generally more complex, comprising multiple azeotropes and distillation regions, resulting in an increased modeling complexity. Due to the integration of distillation columns and a decanter, even the simulation of these processes is considered more challenging, while an optimal process design should include the selection of a suitable solvent, considering the performance of the integrated hybrid process. Yet, the intricate mixture topologies largely impede the use of simplified criteria for solvent selection. To overcome these limitations and allow for a process-based screening of potential solvents, the current work presents a topology-based initialization and optimization approach for designing heteroazeotropic distillation processes. The systematic initialization enables an efficient evaluation of different solvents with different mixture topologies, which is further exploited for optimization-based sensitivity analysis and multi-objective optimization. Three case studies are analyzed with about 170 individually optimized process designs, including stage numbers, feed locations, phase ratios, and heat duties.

Imidazolium Chloride Ionic Liquid Mixtures as Separating Agents: Fuel Processing and Azeotrope Breaking.

Relevant chemical separations for the petrochemical and chemical industries include the removal of aromatic hydrocarbons from aliphatics, the desulfurization and denitrification of fuels, and the separation of azeotropic mixtures containing alkanols. In an attempt to contribute to the development of novel technologies, the potentialities of imidazolium chloride ionic liquid (IL) mixtures as separation agents were investigated. Selectivities, capacities, and solvent performance indices were calculated through the activity coefficients at infinite dilution of organic solutes and water in the imidazolium chloride IL: [C8mim]Cl, [C12mim]Cl, and the equimolar mixture of [C4mim]Cl and [C12mim]Cl. Results show that the imidazolium chloride IL might be appropriately tailored for specific purposes, in which an increase in the proportion of cations containing larger alkyl chains tends to increase the overall affinity with organic solutes. The IL designer solvent concept was explored by comparing the IL equimolar mixture results with the intermediary [C8mim]Cl. The COSMO-RS thermodynamic model was also applied, showing it to be a promising tool for a fast qualitative screening of potential separation agents for specific separation processes.

Performance evaluation and molecular dynamics simulation in the Liquid–liquid extraction process of low transition temperature mixture + n-hexane + 1,2-Dichloroethane

Vinyl sulphate, a new battery additive, can significantly improve battery performance, but its production process generates a large amount of n-hexane + 1,2-dichloroethane (DCE) azeotropic mixtures. In this paper, green and efficient Low Transition Temperature Mixtures (LTTMs) were used as solvents to explore their separation performance and mechanism of the n-hexane + DCE azeotrope system. Firstly, the conductor-like screening model for segment activity coefficient (COSMO-SAC) model was used to investigate the effects of the structure and composition of the hydrogen bond donors and hydrogen bond acceptors on the extraction performance. On this basis, three LTTMs were screened out as solvents for the extraction and separation of n-hexane + DCE by combining experiments, which were trimethylamine hydrochloride-levulinic acid 1:2 (LTTM1), tetraethylammonium chloride-levulinic acid 1:2 (LTTM2), tetraethylammonium chloride-pyruvic acid 1:2 (LTTM3). Afterward, Liquid–liquid equilibrium (LLE) experiments were carried out for the ternary system of n-hexane + DCE + LTTMs, and the results showed that the extraction of DCE was favored by low temperatures in the experimental temperature range. Then, molecular dynamics simulation was used to investigate the microscopic mechanism of the extraction and separation of n-hexane + DCE by LTTMs. The results showed that the interaction between LTTMs and DCE was much larger than that between LTTMs and n-hexane, n-hexane and DCE, which was the fundamental reason for the separation of n-hexane + DCE by LTTMs. Finally, the continuous separation process of n-hexane + DCE was simulated using Aspen Plus, and the results showed that LTTMs had good extraction performance and the purity of n-hexane and DCE products could reach 99.6 mol% and 99.5 mol%, respectively. The feasibility and microscopic mechanism of the extraction and separation of n-hexane + DCE by LTTMs were investigated using a combination of experiments and simulations, which provided a methodological reference for the separation of n-hexane + DCE.

Fabrication of ternary polyvinyl alcohol/tetraethyl orthosilicate/silicotungstic acid hybrid membranes for pervaporation dehydration of alcohol

Herein, we present simple method of fabrication and pervaporation application of organic/inorganic ternary nanocomposite membranes. These are obtained from novel combination of poly(vinyl alcohol)/tetraethyl orthosilicate (PVA/TEOS) along with incorporation of silicotungstic acid (STA) nanoparticles via solution casting method. Physico-chemical structure has been confirmed by using various characterization tools. Pervaporation efficiency of these new nanocomposite membranes in terms of flux and separation factor is investigated for one of the important processes of ethanol separation (azeotropic mixture separation) from its aqueous solution. Dramatically boosted pervaporation separation efficiency by PVA/TEOS membranes has been observed as a result of STA incorporation. The results are also confirmed by calculating diffusion coefficients and activation energies using Fick’s and Arrhenius equations, respectively.

Sustainable separation of ternary azeotropic mixtures based on enhanced extractive distillation/pervaporation structure and multi-objective optimization

The development of an efficient separation and purification process for ternary aqueous azeotropes is very important to balance their economic and environmental benefits. Based on the high efficiency of extractive distillation in azeotrope separation and the low consumption of pervaporation technology, it is essential to study the feasibility of the coupling process and its advantages when compared with the single distillation process. Considering a tetrahydrofuran/toluene/water azeotropic system, suitable extractants for the process of extracting and rectifying azeotropes were selected by analyzing the phase equilibrium and intermolecular interaction bonding mechanism. Implementing the non-dominated sorting genetic algorithm with economic cost and gas emissions (CO2, SO2 and NOx) as the multi-objective for process optimization, the optimal parameters and process scheme of extractive distillation and coupling process were obtained. In addition, different azeotrope feed compositions were analyzed to further judge the separation effect of the coupling process. Based on the multi-objective optimization algorithm, it was found that the coupled process was better than the single extractive distillation process economically and environmentally, which has significance for the separation of ternary aqueous azeotropes.

Process intensification by integration of distillation and vapor permeation or pervaporation - An academic and industrial perspective

Since membrane separations, such as vapor permeation (VP) or pervaporation (PV), are not limited by vapor-liquid equilibrium, their coupling with distillation can exert a synergistic effect, overcome the thermodynamic limits of distillation, and improve energy efficiency, especially suitable for the separation of azeotropic mixtures that otherwise requires special distillation processes. Therefore, there is an increasing number of such studies, and it is of great significance to comprehensively explore the process integration of distillation with VP or PV. This review first introduces the mechanism model of membrane separation and membrane materials, then comprehensively summarizes the academic research in terms of hybrid configurations of distillation with VP or PV in the following aspects: separation of azeotropic or close-boiling mixtures, promoting reactions by selectively removing a product, and energy savings, providing guidelines for subsequent application and future research. Finally, this review gives typical industrial cases of distillation and membrane-coupled separation processes and highlights some deficiencies of current research in this area.

Analysis and performance enhancement of heat pump technology assisted pressure-swing distillation process in the separation of azeotropic mixtures

In this paper, vapor recompressed heat pump assisted pressure-swing distillation process (VRC-PSD) is proposed to explore the ethyl acetate/n-hexane and THF/ethanol/water separating process based on the method explored for defining optimal vapor recompressed heat pump assisted distillation process in our early work. In binary separating process, the VRC-ABR-PSD and VRC-PRE-PSD configurations, respectively, reduce the 52.927% and 52.427% in TAC. And the VRC-ABR-PSD and VRC-PRE-PSD process applied in the separation of THF/ethanol/water ternary azeotrope can reduce TAC by 62.640% and 58.752%.The result demonstrates that all VRC-PSD schemes perform better than the corresponding PSD scheme in terms of economic, energy saving and thermodynamic efficiency. And VRC-PSD scheme with auxiliary bottom reboiler performs better than the VRC-PSD scheme with preheater. Meanwhile, the VRC-PSD assisted with heat integration schemes show better performance than those schemes without heat integration. For the separation of THF/ethanol/water ternary azeotrope, the VRC-ARB-HI-PSD and VRC-PRE-HI-PSD scheme reduce TAC by 67.359% and 63.257%.

NiO nanowire-containing heat transfer nanofluids for CSP plants: Experiments and simulations to promote their application

Concentrating solar power (CSP) is considered a clean, renewable and sustainable energy with a significant potential to become an alternative to polluting fossil fuel-based technologies. Among CSP collectors, parabolic-trough collectors (PTC) are the most mature technology, representing nearly 90% of the currently installed collectors in CSP plants worldwide. In this technology, a heat transfer fluid (HTF) carries the thermal energy absorbed to a power block to produce electricity. Improving the thermal properties of the conventional HTF could lead to an improvement of the efficiency of CSP plants. In this sense, the use of nanofluids as the HTF in these plants can be a promising choice. Here, polycrystalline NiO nanowire-containing nanofluids have been prepared using the conventional HTF used in CSP plants as the base fluid; that is, the eutectic and azeotropic mixture of biphenyl (26.5%) and diphenyl oxide (73.5%). The stability, rheological and thermal properties have been characterized, and an analysis of the performance of the nanofluids prepared in standard and volumetric absorbers have been carried out. The overall CSP system performance can be increased up to 34.8% using the nanofluid in a surface collector or up to 34.3% using the nanofluid in a volumetric collector, which are better than the predicted 28.5% using the conventional HTF in a standard surface collector, thanks to the improvements in thermal properties, both specific heat and thermal conductivity. Finally, from molecular dynamics simulations we determined that the mean free path of thermal vibrations is longer for monocrystalline NiO nanowires. Thus, the development of strategies for obtaining this kind of nanostructures is of great interest because they can further improve the efficiency of these nanofluids.

Solvent-engineering-processed CsPbIBr2 inorganic perovskite solar cells with efficiency of ∼11%

Recently, the cesium lead halide perovskite (CsPbIBr2) materials demonstrating the most balanced bandgap and stability among all inorganic perovskite analogs have received great attention in photovoltaic community. However, the poor quality of solution-processed CsPbIBr2 films with small grains and massive voids and defects severely impedes its further development. This obstacle issue mainly roots from the slow crystallization process of perovskites when using traditional high boiling point solvent of dimethyl sulfoxide (DMSO). Herein, a novel solvent engineering strategy, namely alcohol-induced rapid crystallization process, is originally developed. We intentionally add some low boiling point alcohols, such as methanol, ethanol, isopropanol, and n-butanol, to form a lower boiling point DMSO-alcohol azeotropic mixture, which can be volatilized quickly and effectively accelerate the crystallization process of CsPbIBr2 films. Meanwhile, we elaborately adopt some CsI additives to suppress the intrinsic self-doping and passivate the defects of perovskites. Besides, the influence of annealing temperatures on the film quality and device performance is also investigated in this study. Consequently, the pinhole-free, highly crystallized CsPbIBr2 films with large grains and a preferable (100) orientation are successfully achieved via CsI/methanol treatment recipe when annealed at the optimized temperature of 280 °C. The as-obtained perovskite solar cells (PSCs) with a superior long-term stability feature yield a highly promising power conversion efficiency (PCE) of 11.49%. To our knowledge, this is the highest reported efficiency among all CsPbIBr2 inorganic PSCs.

Performance Assessment of Solar Parabolic Trough Collector-Assisted Combined Organic Rankine Cycle and Triple Pressure Level Ejector-Absorption Refrigeration Cycle

Abstract A novel solar-assisted combined power and cooling system comprising a parabolic trough collector (PTC) assisted organic Rankine cycle (ORC) and ejector-absorption cooling cycle (EARC) is presented and analyzed in this paper. The use of Ammonia-Lithium Nitrate (NH3-LiNO3) as the working pair in EARC is investigated. First and second law thermodynamics analysis revealed that PTC accounted for 60–80% of the total exergy destruction. Using different ORC fluids revealed that Toluene showed the best performance. The energy utilization factor of Toluene is found to be 25.31% at turbine inlet temperature of 550 K and solar irradiation of 1 kW/m2, whereas for other ORC fluids like R134a (tetrafluoroethane, CH2FCF3), R245fa (pentafluoropropane, CF3CH2CHF2), n-pentane, R410a (near azeotropic mixture of difluoromethane, CH2F2 and pentafluoroethane, C2HF5), it was found to be 17–20%. The exergy efficiency of the combined system using Toluene has reached up to 17%, while the rest of the ORC fluids exhibited 8–12% exergy efficiency. The pump power consumption was significantly reduced due to the use of the ejector in the EARC. Generator temperature and solution heat exchanger (SHX) effectiveness were also found to highly influence the performance of the refrigeration system.

Sensitivity Analysis of Bioethanol Simulation from Microalgae with Pressure Swing Distillation Process

Energy is an important parameter in the social and economic development of a country. Thus, it is necessary to seek renewable energy to supply energy needs in Indonesia. The production of bioethanol from microalgae as a biofuel is one way to reduce the use of fossil fuels. Microalgae has an advantage over other types of biomass sources due to its high biomass productivity and do not compete with agricultural crops for land and water resources. In the bioethanol production process, the ethanol and water form an azeotrope mixture of 95.6% of ethanol at 1 atm and 78.15°C. The objective of this research was to analyse and determine the operating conditions and the optimum distillation column configuration which results in high ethanol purity according to fuel specifications (fuel grade ethanol). The method of pressure-swing distillation was applied to separate the azeotrope of ethanol-water and obtain high purity ethanol. A simulation model of bioethanol production with pressure-swing distillation system was conducted by using Aspen Plus V10. In this research, the influence of process parameters such as distillation column pressure, reflux ratio, feed stage location, and the number of theoretical stages was analysed by using model analysis tools. The results showed that the obtained bioethanol purity of 99.9% with the condenser and reboiler duty of the LP column -79.931 kW and 667.651 kW, respectively; while the HP column is -47.627 kW and 57.698 kW.

Упрощенный способ синтеза триацетина – пищевой добавки E1518

Aim. Development of a simplified technology for the production of triacetin – a food additive (E1518) and a water-retaining agent. Materials and Methods. The following main raw materials were used: distilled glycerol 99.5% (LLC «Ukrkhimresursy», Ukraine), glacial acetic acid (LLC «Chemical Alliance», Russia). It is proposed to control the content of unreacted products – glycerol – spectrophotometrically with copper (II), and acetic acid – by acid-base titration. Results. The conditions for the synthesis of triacetin are as follows: the molar ratio of glycerol and acetic acid is 1:6, temperature – 120-125оC, duration – 90 minutes. The distillation of excess acetic acid was carried out at a temperature of 130-140оC for 3 hours, which ensured the receipt of 100% of the product – triacetin, which contains trace amounts of acetic acid. The residual content of acetic acid in the final product is not more than 0.01% of the mass. After distillation, acetic acid is obtained with a concentration of 79-80% (azeotropic mixture). The use of a catalyst – sulfuric acid – negatively affects the color of the final product (from yellow to light brown) and pH (about an 0). The use of a hydrobromic acid catalyst does not lead to a 100% product, but it negatively affects the pH of the finished product (near zero), which requires additional purification of the final product (vacuum distillation) and neutralization, which in turn contaminates the product with inorganic salts. Conclusion. A simplified method for the synthesis of triacetin from glycerol and acetic acid has been developed, which excludes the use of catalysts, vacuum, and sorption purification.