Process design and intensification of multicomponent azeotropes special distillation separation via molecular simulation and system optimization

This work provides an overview of distillation processes,including process design for different distillation processes,selection of entrainers for special distillation processes,system integration and intensification of distillation processes,optimization of process parameters for distillation processes and recent research progress in dynamic control strategies.Firstly,the feasibility of using thermodynamic topological theories such as residual curve,phase equilibrium line and distillation boundary line to analyze different separation regions is discussed,and the rationality of distillation process design is discussed by using its feasibility.Secondly,the application of molecular simulation methods such as molecular dynamics simulation and quantum chemical calculation in the screening of entrainer is discussed for the extractive distillation process.The thermal coupling mechanism of different distillation processes is used to explore the process of different process intensifications.Next,a mixed integer nonlinear optimization strategy for the distillation process based on different algorithms is introduced.Finally,the improvement of dynamic control strategies for different distillation processes in recent years is summarized.This work focuses on the application of process intensification and system optimization in the design of distillation process,and analyzes the challenges,prospects,and development trends of distillation technology in the separation of multicomponent azeotropes.

Environmental,economic and exergy analysis of separation of ternary azeotrope by variable pressure extractive distillation based on multi-objective optimization

In this work,the ternary azeotrope of tert-butyl alcohol/ethyl acetate/water is separated by extractive distillation(ED)to recover the available constituents and protect the environment.Based on the conductor like shielding model and relative volatility method,ethylene glycol was selected as the extractant in the separation process.In addition,in view of the characteristic that the relative volatility between components changes with pressure,the multi-objective optimization method based on nondominated sorting genetic algorithm II optimizes the pressure and the amount of solvent cooperatively to avoid falling into the optimal local solution.Based on the optimal process parameters,the proposed heat-integrated process can reduce the gas emissions by 29.30%.The heat-integrated ED,further coupled with the pervaporation process,can reduce gas emission by 42.36%and has the highest exergy efficiency of 47.56%.In addition,based on the heat-integrated process,the proposed two heat pump assisted heat-integrated ED processes show good economic and environmental performance.The double heat pump assisted heat-integrated ED can reduce the total annual cost by 28.78%and the gas emissions by 55.83%compared with the basis process,which has a good application prospect.This work provides a feasible approach for the separation of ternary azeotropes.

Economy, environmental assessment and energy conservation for separation of isopropanol/diisopropyl ether/water multi-azeotropes via extractive distillation coupled pervaporation process

This wok proposed the extraction distillation coupled pervaporation(ED+PV) technology process using two different solvents to separate isopropanol(IPA) and diisopropyl ether(DIPE) from DIPE/IPA/H_(2)O ternary heterogeneous azeotropes in industrial wastewater from the synthesis of isopropanol in this study.Based on strict design specifications, simulation and sequential iteration methods are used for process design and optimization. Compared to the ethylene glycol(EG)-EG+H_(2)O process and the 1,3-propanediol(PDO)-IPA+H_(2)O process, the total annual cost(TAC) of the EG-IPA+H_(2)O process decreased by 20.76% and 7.86%(PDO). Compared to the EG-EG+H_(2)O process, the TAC of the PDO-IPA+H_(2)O process reduced 14%, but the global warming potential(GWP) and human toxicity of the PDO-IPA+H_(2)O process increased 11.3% and 4.07% respectively. Compared to the PDO-IPA+H_(2)O process, the EG-IPA+H_(2)O process saves 7.86%(TAC), 9.78%(GWP) and 9.85%(human toxicity). The ED+PV process with EG is superior to PDO in factors of TAC, energy consumption, human toxicity and environment. The EG-IPA+H_(2)O process changed the separation order of the products of the multi-azeotropic system, reduced the cost and energy conservation of the system, and enhanced the environmental protection evaluation of the process, is the best process through life cycle assessment for analyzing the economy, energy conservation, environmental assessment and human toxicity, designing cleaner products, controlling waste discharge, and promoting the chemical purification industry. This work provides a new process design and optimized separation ideas, will have a good guiding significance for the research and application separation of multi-azeotropic mixture with mixed solvents in organic wastewater from the cleaner chemical production, has been up to standard wastewater discharge process, and realized the development goal of carbon peak and carbon neutrality in the sustainable development of chemical clean industry.

Energy,exergy,economic and environmental comprehensive analysis and multi-objective optimization of a sustainable zero liquid discharge integrated process for fixed-bed coal gasification wastewater

For a long time,China's regional water resource imbalance has restricted the development of coal chemical industry,and it is imperative to achieve zero liquid discharge(ZLD).Therefore,the game relationship between technical indicators,costs and emissions in ZLD process of fixed-bed coal gasification wastewater treatment process should be explored in detail.According to the accurate model,the simulation for ZLD of fixed-bed coal gasification wastewater treatment process is established,and this process is assessed from the perspective of thermodynamics,economy,and environment.The total energy consumption of ZLD process before optimization is 4.032×10^(8)W.The results of exergy analysis show exergy destruction of ZLD process is 94.55%.For economic and environmental results,the total annual cost is 1.892×10^(7)USD·a^(-1)and the total environmental impact is 4.782×10^(-8).The total energy consumption of the optimal six-step ZLD process based on multi-objective optimization is 4.028×10^(8)W.The CO_(2)content in the treated wastewater is 0.1%.This study will have an important role in promoting the establishment of the ZLD process for coal chemistry industry.

Separation of fuel additives based on mechanism analysis and thermodynamic phase behavior

tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust emissions.Therefore,the recovery of these compounds from azeotropic systems is of great significance.Ionic liquids(ILs)are promising green solvents for separating azeotropic systems.In this study,an efficient extraction strategy based on 1-butyl-3-methylimidazolium acetate([Bmim][AC])is proposed.The mechanism by which ILs enable the separation of binary alcohol-ester azeotropes was revealed by evaluating the lowest conformational energy through combining an independent gradient model based on the Hirshfeld partition(IGMH)and frontier molecular orbitals,to preliminarily screen the extractants.The range of extractants was further reduced by a vapor–liquid phase equilibrium(VLE)experiment,and a modeling method for separating the alcohol–ester system and recovering the solvent using[Bmim][AC]and 1-ethyl-3-methyl-3-imidazolium acetate([Emim][AC])is established.Under the optimal operating conditions,the use of[Bmim][AC]can reduce the total annual cost(TAC)per year by 17.78%,and the emissions of CO_(2),SO_(2),and NO can be reduced by 10.86%.In this study,a comprehensive method for screening extractants is proposed,and the simulation process is optimized in combination with the economic and environmental impact.The results have important guiding significance for realizing efficient,energy-saving,and green azeotropic separation systems in industry.

Comprehensive analysis on the economy and energy demand of pressure-swing distillation and pervaporation for separating waste liquid containing multiple components

A large amount of waste liquids containing methanol/acetone/water mixtures are produced in the synthesis of methyl methacrylate(MMA).Under the advocacy of green chemical industry,it is urgent to develop an efficient,economic and energy-saving mixture separation process.Through thermodynamic azeotropic behavior and pressure sensitivity analysis,pressure-swing distillation was determined and the optimal separation pressure of each column in the process was obtained.Due to the composition of waste liquids produced were quite different in MMA production,the pressure-swing distillation separation process was designed to fully achieve the accurate waste liquids treatment.Taking the total annual cost(TAC)as the target,the sequential iteration method was used to optimize the process,and the impact of composition on economy was compared.In order to further realize the energy-saving of the separation process,the pervaporation membrane module was introduced to pretreat the waste liquid in the pressure-swing distillation.The results showed that the TAC of the coupling process was 46% higher than that of the pressure-swing distillation process,and the thermodynamic efficiency was 30% higher.This study provides waste liquid treatment technology for enterprises and analyzes its economic and energy efficiency,which has reference significance for the development of coupled separation technology.

A review of extractive distillation from an azeotropic phenomenon for dynamic control

Extractive distillation is an effective method for separating azeotropic or close boiling point mixtures by adding a third component.Various technologies for performing the extractive distillation process have been explored to protect the environment and save resources.This paper focuses on the improvement of these advanced technologies in recent years.Extractive distillation is retrieved and analyzed from the view of phase equilibrium,selection of solvent in extractive distillation,process design,energy conservation,and dynamic control.The quantitative structure–property relationship used in extractive distillation is discussed,and the future development of extractive distillation is proposed to determine how the solvent affects the relative volatility of the separated mixture.In the steady state design,the relationship between the curvature of the residue curve and parameters of the optimal steady state is also highlighted as another field worthy of further study to simplify the distillation process.

QSPR modeling of azeotropic temperatures and compositions for binary azeotropes containing lower alcohols using a genetic function approximation

Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results;however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship(QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary azeotropes containing lower alcohols. The QSPR models for 64 binary azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation(GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted.External tests of an additional 16 azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the azeotropes,and good predictive ability was obtained within acceptable prediction error levels.

Effect of thermodynamic parameters on prediction of phase behavior and process design of extractive distillation

Extractive distillation was investigated for separation of the minimum azeotrope of n-propanol/water, via the Aspen Plus simulation platform. Experimental data of n-propanol/water, which could pass the thermodynamic consistency test, were regressed to get suitable binary interaction parameters(BIPs) by the UNIQUAC thermodynamic model. The azeotrope system was heterogeneous in the simulation with built-in BIPs, which was contrary to the experimental data. The study focused on the effect of thermodynamic parameters on the prediction of phase behavior, and process design of extractive distillation. N-methyl-2-pyrrolidone(NMP) and ethylene glycol were used as solvents to implement the separation. Processes with built-in and regressed BIPs were explored,based on the minimum total annual cost(TAC). There were significant differences in the phase behavior simulation using different thermodynamic parameters, which showed the importance of BIPs in the design and optimization of extractive distillation.

Separation of n-heptane and tert-butanol by ionic liquids based on COSMO-SAC model

In the process of liquid-liquid extraction,it is necessary to look for green solvents as extractants.Ionic liquids have been studied as extractants due to their green recyclability in recent years.The infinite dilution activity coefficients of 100 ionic liquids with a combination of 10 cations and 10 anions were calculated by COSMO-SAC model,and theσ-profiles were plotted.The distribution coefficient and separation coefficient of n-heptane+tert-butanol+ILs were determined.[OMIM][OTF],[HMIM][OTF]and[BMIM][OTF]were selected as solvents for this study.The interaction energy,bond length and charge density of ionic liquids with tert-butanol were calculated by quantum chemistry calculation method.According to these results,the rationality of selected ionic liquids as extractants could be analyzed from the molecular level.At 298.15 K and 101.325 kPa,the liquid-liquid equilibrium data of the ternary system{n-heptane+tert-butanol+[OMIM][OTF],nheptane+tert-butanol+[BMIM][OTF],n-heptane+tert-butanol+[HMIM][OTF]}were measured.The distribution coefficient and separation coefficient for judging the extraction effect were obtained.The NRTL model was used to correlate liquid-liquid equilibrium experimental data,and correlation result proved that the correlated and experimental data had a good correlation.The research on ionic liquids is of great significance to the development of green and sustainable chemical industry.

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection(PSDIC) process of ethyl acetate and ethanol separation were investigated.The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced.This control structure did not require the control of the flowrate of the side stream.The dynamic controllability of PSDIC with partial heat integration(PHIPSDIC) was also explored.The improved control structure can effectively control ±20% feed disturbances.However,in industrial production,simple controller,sensitive and easy to operate,is the optimal target.To avoid the use of component controllers or complex control structure,the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased,albeit by incurring a slight rise in the total annual cost(TAC).This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.

Mechanism analysis of solvent selectivity and energy-saving optimization in vapor recompression-assisted extractive distillation for separation of binary azeotrope

Octane and p-xylene are common components in crude gasoline,so their separation process is very important in petroleum industry.The azeotrope and near azeotrope are often separated by extractive distillation in industry,which can realize the recovery and utilization of resources.In this work,the vapor–liquid equilibrium experiment was used to obtain the vapor–liquid equilibrium properties of the difficult separation system,and on this basis,the solvent extraction mechanism was studied.The mechanism of solvent separation plays a guiding role in selecting suitable solvents for industrial separation.The interaction energy,bond length and charge density distribution of p-xylene with solvent are calculated by quantum chemistry method.The quantum chemistry calculation results and experiment results showed that N-formylmorpholine is the best solvent among the alternative solvents in the work.This work provides an effective and complete solvent screening process from phase equilibrium experiments to quantum chemical calculation.An extractive distillation simulation process with N-formylmorpholine as solvent is designed to separate octane and p-xylene.In addition,the feasibility and effectiveness of the intensified vapor recompression assisted extraction distillation are also discussed.In the extractive distillation process,the vapor recompression-assisted extraction distillation process is globally optimal.Compared with basic process,the total annual cost can be reduced by 43.2%.This study provides theoretical guidance for extractive distillation separation technology and solvent selection.

Separation of isopropyl alcohol+isopropyl acetate azeotropic mixture:Selection of ionic liquids as entrainers and vapor-liquid equilibrium validation

Based on the COSMO-SAC model,1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium p-toluenesulfonate were selected from 30 ILs as entrainers to investigate the separation of the isopropyl alcohol+isopropyl acetate azeotrope.Two screening indicators,σ-profile and infinite dilution selectivity(S^(∞)),were adopted as the basis.The iso baric vapor-liquid equilibrium experiments for isopropyl alcohol+isopropyl acetate binary system and isopropyl alcohol+isopropyl acetate+confirmed ILs ternary systems were performed at the pressure of atmospheric pressure.The experimental measurement demonstrated that the adopt ILs enhanced the relative volatility of the above alcohol-ester azeotrope,leading to the elimination of the azeotropic point with a certain amount ILs.Meanwhile,the thermodynamic correlation for two systems containing ILs was explored with the NRTL model,which also reflects the extensive applicability of that by comparing the deviation between experimental and calculated data.And its binary interaction parameters were regressed,which can provide a basis for its simulation process.

Determination of the Nucleation Region Location of Si Nano-Crystal Grains Prepared by Pulsed Laser Ablation through Changing Position of Substrates

To determine the nucleation region location of Si nano-crystal grains, pulsed laser ablation of Si target is performed in Ar gas of 10 Pa at room temperature with laser fluence of 4 J/cm2, the substrates are located horizontal under ablation spot with different vertical distance. Characteristics of deposited grains are described by scanning electron microscopy, Raman scattering and X-ray diffraction spectra, the results indicate that deposition position on substrates in a certain range is relative to target surface, which changes according to different vertical distance of substrates to ablation spot. Grain size increased?at first and then decreased with addition of lateral distances to target in the range, but the integral distribution rule was independent of position of substrates. Combining with hydrodynamics model, nucleation division model, thermokinetic equation and flat parabolic motion, spatial nucleation region location of grains is obtained through numerical calculations, which is 2.7 mm-43.2 mm to target surface along the plume axis.

Room-temperature and atmospheric-pressure hydrogenation of lignin-derived phenol to KA oil by Pt/NiO@MOFs

Hydrogenation of lignin-derived phenol to KA oil(the mixture of cyclohexanone(K)and cyclohexanol(A))is attractive yet challenging in the sustainable upgrading of biomass derivatives under mild conditions.Traditional supported metal catalysts have been widely studied but the active components on supports often exhibit low recyclability due to their instability under experimental conditions.Here we show fabricating ultrasmall Pt/NiO in the pores of chromium terephthalate MIL-101 as catalysts for hydrogenation of phenol.Impressively,Pt/NiO@MIL-101 achieves catalytic phenol hydrogenation to KA oils of tunable K/A ratios and good reusability under room temperature and atmospheric hydrogen pressure,superior to contrast Pt@MIL-101 and Pt/NiO samples.Such excellent performance mainly originates from the effective adsorption and activation of phenol by coordinatively unsaturated Cr sites and H2 activation on ultrasmall Pt/NiO as well as its effective spillover to the adsorbed phenol over Cr sites for hydrogenation reaction.Substantially,such catalyst also displays the excellent performances for hydrogenation of phenol’s derivatives under mild conditions.

A Soft Sensor with Light and Efficient Multi-scale Feature Method for Multiple Sampling Rates in Industrial Processing

In industrial process control systems,there is overwhelming evidence corroborating the notion that economic or technical limitations result in some key variables that are very difficult to measure online.The data-driven soft sensor is an effective solution because it provides a reliable and stable online estimation of such variables.This paper employs a deep neural network with multiscale feature extraction layers to build soft sensors,which are applied to the benchmarked Tennessee-Eastman process(TEP)and a real wind farm case.The comparison of modelling results demonstrates that the multiscale feature extraction layers have the following advantages over other methods.First,the multiscale feature extraction layers significantly reduce the number of parameters compared to the other deep neural networks.Second,the multiscale feature extraction layers can powerfully extract dataset characteristics.Finally,the multiscale feature extraction layers with fully considered historical measurements can contain richer useful information and improved representation compared to traditional data-driven models.

Recent advances in bimetallic metal-organic frameworks and their derivatives for thermal catalysis

Compared with monometallic metal-organic frameworks(MOFs)that are synthesized by reacting inorganic metal ions or clusters with bidentate or multidentate ligands via hydrothermal or solvothermal methods,the construction of heterogeneous frameworks like at least two kinds of metal sites in the individual nodes is proved to be an effective way to modulate their properties for advanced catalysis,especially for selective catalysis and multifunctional catalysis.However,it is still very challenging to precisely characterize their microstructures and reveal the relationship among the composition,structure,and their performances.Therefore,it is necessary to summarize the recent progress on bimetallic MOFs for thermal catalysis.First,we summarize the synthesis strategies and characterization methods of bimetallic MOFs and their derivatives.Second,the application of bimetallic MOFs and their derivatives as catalysts in thermal catalysis is discussed,and the relationship among the active components,structures,and their properties is elucidated.Third,the potential challenges and prospects of bimetallic MOF based nanocatalysts are proposed.This review will bring some insights into the design and preparation of bimetallic MOFs based nanocatalysts in the future.

Determination of a suitable index for a solvent via two-column extractive distillation using a heuristic method

The traditional approach to solvent selction in the extractive distillation process strictly focuses on the change in the relative voltility of light-heavy components induced by the solvent.However,the total annual cost of the process may not be minimal when the solvent induces the largest change in relative volatility.This work presents a heuristic method for selecting the optimal solvent to minimize the total annual cost.The functional relationship between the relative volatility and the total annual cost is established,where the main factors,such as the relative volatility of the light-heavy components and the relative volatility of the heavy-component solvent,are taken into account.Binary azeotropic mixtures of methanol-toluene and methanol-acetone are separated to verify the feasibility of the model.The results show that using the solvent with the minimal two-column extractive distillation index,the process achieves a minimal total annual cost.The method is conducive for sustainable advancements in chemistry and engineering because a suitable solvent can be selected without simulation verification.

Recent advances in hollow metal-organic frameworks and their composites for heterogeneous thermal catalysis

Hollow metal-organic frameworks(Ho MOFs)as emerging materials have been arousing great interest in heterogeneous catalysis with respect to the solid counterparts,mainly because of their unique and intriguing features such as high surface to volume ratio,large void space,short channel length,and more exposed active sites.To achieve diverse catalysis,it is of great importance to combine Ho MOFs with other active components for constructing smart composites.In this review,the recent advances in Ho MOFs and their composites for heterogeneous catalysis are summarized.Firstly,the synthetic strategies for various Ho MOFs with single shell,double shells or multiple shells are summarized,while their composites with yolk-shell,hollow sandwich and hollow satellite structures are described.Secondly,various catalytic reactions over Ho MOFs and their composites are discussed,and moreover,the relationships among the active components,structures and their performances are illustrated.Thirdly,the potential challenges and future development on Ho MOFs-based nanocatalysts are proposed.This review will bring some insights for better design and fabrication of heterogeneous nanocatalysts with the well-defined hollow structures.

Energy efficiency and area spectral efficiency tradeoff for coexisting wireless body sensor networks

The coexistence of wireless body sensor networks(WBSNs) is a very challenging problem, due to strong interference, which seriously affects energy consumption and spectral reuse. The energy efficiency and spectral efficiency are two key performance evaluation metrics for wireless communication networks. In this paper, the fundamental tradeoff between energy efficiency and area spectral efficiency of WBSNs is first investigated under the Poisson point process(PPP) model and Matern hard-core point process(HCPP) model using stochastic geometry. The circuit power consumption is taken into consideration in energy efficiency calculation. The tradeoff judgement coefficient is developed and is shown to serve as a promising complementary measure. In addition, this paper proposes a new nearest neighbour distance power control strategy to improve energy efficiency. We show that there exists an optimal transmit power highly dependant on the density of WBSNs and the nearest neighbour distance. Some important properties are also addressed in the analysis of coexisting WBSNs based on the IEEE 802.15.4 standard, such as the impact of intensity nodes distribution,optimal guard zone, and outage probability. Simulation results show that the proposed power control design can reduce the outage probability and enhance energy efficiency. Energy efficiency and area spectral efficiency of the HCPP model are better than those of the PPP model. In addition, the optimal density of WBSNs coexistence is obtained.