Amino Ethers of Ortho-Phosphoric Acid as Extragents for Ethanol Dehydration

Amino ethers of ortho-phosphoric acid prepared using triethanolamine; ortho-phosphoric acid; polyoxyethylene glycol, diethylene glycol, triethylene glycol and glycerol (AEPA-DEG/TEG/Gl) were investigated as extractants for the separation of aqueous ethanol solutions by extractive distillation. Using the method of open evaporation, the influence of the molecular structure of AEPA-DEG/TEG/Gl on the conditions of vapor–liquid equilibrium in ethanol–water solutions was studied. It has been shown that the addition of AEPA-DEG/TEG/Gl removes the azeotropic point. At the same time, the observed effect turned out to be significantly higher in comparison with the use of pure glycerol or glycols for these purposes. The UNIFAC model was used to calculate the activity coefficients in a three-component ethanol–water–AEPA-DEG/TEG/Gl mixture. Within the framework of this model, a division of AEPA-DEG/TEG/Gl molecules into group components is proposed. Previously unknown parameters of the groups PO–CH, PO–CH2, PO–OCH2, PO–NHCH2, PO–OH, and PO–H2O were determined from our own and published experimental data. The concentration dependences of the density and dynamic viscosity of AEPA-Gl aqueous solutions have been experimentally measured. Experimental studies of the extractive distillation of ethanol–water using AEPA-Gl as an extractant have been carried out in a column with bubble cap plates and a packing, and its high efficiency has been established.

Modeling of Technological Processes for a Rectification Plant in Second-Generation Bioethanol Production

The article deals with the recent developments in the fuel industry, considering the permanent increasing requirements for fuel quality and environmental safety. The work aims to study various technological modes at the rectification unit to produce fuel bioethanol from lignocellulosic biomass. The main goals are to solve applied scientific problems of rational designing and technological optimization to obtain boundaries of energy consumption to ensure the quality of bioethanol sufficient for a consumer. Recent approaches for numerical simulation of chemical technological processes were applied to study the operating processes and optimize technological parameters. The plant model was designed from various modules that allow us to simulate technological processes efficiently and accurately for all the primary units of the rectification equipment. The methodology based on the activity coefficient UNIFAC model of phase equilibrium was applied. As a result, a mixture with 74% of bioethanol 9% of impurities was obtained in the brew column. In the epuration column, a mixture of 46% bioethanol and 2.2% of impurities was obtained in bottoms. Finally, in the alcohol column, the mass fraction of distillate of 96.9% and impurities of 2.7% were reached. The numerical simulation results can be applied in recent fuel technologies and designing the corresponding biofuel plants.

Biomass fast pyrolysis: Chemistry and thermodynamics

<p>The project, PYROKINE, aims at developing new modeling approaches adapted to one of the most promising thermochemical processes, fast pyrolysis, applied to the conversion of contaminated lignocellulosic biomass. The fast pyrolysis converts solid biomass into volatiles and a limited amount of char. The volatiles are then rapidly quenched resulting in a high yield of bio-oil, 70-75wt% of the starting material on a dry basis. The liquified biomass can be further upgraded catalytically or blended to produce new advanced biofuels. In addition to the yield, the product distribution determines their quality, and this is critically dependent on biomass type and its temperature-time history. In the present study, we propose to establish a dynamic model adaptable to the conversion of different biomass types under various pyrolysis regimes according to two research programs.</p><p>The first program consists of integrating coupled chemical kinetics into heat and mass transfer models for biomass fast pyrolysis. So far, the coupled kinetic model combining the Friedman isoconversional method with a Distributed Activated Energy Model (DAEM) has been developed and validated with a set of experimental data obtained under slow heating conditions. The apparent activation energy, Eα, one of the kinetic parameters that describes the overall reactivity of the feedstock, has been plotted versus the extent of conversion, α, to assess the chemical complexity of the reaction. For example, the lignin was found to degrade into two successive stages from 174 to 280kJ/mol between 0.05<α<0.60 and up to 322kJ/mol until α=0.85. Two kinetic parameter datasets were derived and used as inputs for the double-Gaussian DAEM that successfully fitted experimental curves. This chemical kinetic model will be combined with heat and mass transport models according to the type of thermal regimes.</p><p>The second program focuses on the thermodynamic and kinetic modeling of the intermediate liquid compound in the presence of metallic species. This liquid appears in the early stages of the fast pyrolysis and results from the softening of biomass. Its physico-chemical characteristics are the origin of the multiphasic nature of the biomass fast pyrolysis. A preliminary study has allowed the development of a thermodynamic model and headspace coupled to gas chromatographic methods to predict the vapor-liquid equilibrium for model liquid mixtures. The system studied was a closed system with air and a solution mixture of five components (acetic acid, hydroxyacetone, phenol, furfural, and methanol) near its boiling point, 90°C, and under atmospheric pressure. To predict the thermophysical parameters of the solution, the Soave-Redlich-Kwong (SRK) equation of state coupled with Modified Huron-Vidal (MHV2) mixing rules incorporating the UNIversal Functionnal Activity Coefficient (UNIFAC) model was implemented. Concentration measurements in vapor and liquid phases were compared to vapor-liquid equilibrium data. A quantitative agreement between simulated and measured concentrations in the liquid phase was achieved with this combined state-predictive model of the SRK-MHV2-UNIFAC model, confirming that it accounts well for the nonidealities. This thermodynamic model will need to be coupled with a chemical kinetic model in the presence of inorganics to reveal the role of those contaminants on the chemistry.</p>

Predictions of the vapor-liquid equilibrium data for low-GWP Hydrofluorocarbons + polyethylene-glycol dimethylether solvents by modified UNIFAC model

The working fluids are crucial for developing the absorption refrigeration system. Our previous work has proposed three novel working pairs, which uses the low-GWP HFCs (R32, R152a and R161) as the refrigerants and the polyethylene-glycol dimethylether solvent DMETEG as the absorbent. To explore the VLE behaviors of HFCs in other longer chain structures of polyethylene-glycol dimethylether solvents, the modified UNIFAC (Dortmund) model was applied for prediction. The previous binary parameters showed large deviations from the experimental data. Then the new binary parameters were obtained by regression. For R32+DMEDEG and R152a/R161+DMETrEG, the prediction ARAD results were reduced from 17.13%, 24.06% and 12.48% to 3.71%, 2.61% and 6.86%, respectively. Finally, the VLE data of R161 + PGDE at the temperatures of 293.15-343.15K were predicted.

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.

Liquid-liquid Equilibrium Determination and Data Correlation for 2,2,4-trimethyl Pentane - tripropylene Glycol Binary System

Liquid-liquid equilibrium at temperatures between 293.16K and 353.1K for the mixture of 2,2,4-trimethylpentane + 2- [2- (2-Hydroxypropoxy) propoxy] -1-propanol was determined using the cloud point method. The measured data was used to estimate the binary interaction parameters of NRTL thermodynamic model, through non-linear regression using MATLAB� software. The binary interaction parameters resulting from regression were used further in a chemical simulation software (PRO/II 9.3) to determine the LLE for the studied mixture. The LLE calculation results obtained with the NRTL model were compared with the results of LLE calculations using the predictive thermodynamic model-UNIFAC. It was determined that the results of the calculation of the LLE using binary interaction parameters obtained through regression have a smaller deviation from the experimental data than the results of the calculation performed using the UNIFAC model. Moreover, the binary interaction parameters obtained from regression were utilized for the estimation of the solvency properties of tripropylene glycol considering the extraction of C8 aromatics from a mixture containing 2,2,4-trimethyl pentane, ethylbenzene and xylenes.