Innovation in a Continuous System of Distillation by Steam to Obtain Essential Oil from Persian Lime Juice (Citrus latifolia Tanaka)

The citrus industry is one of the most important economic areas within the global agricultural sector. Persian lime is commonly used to produce lime juice and essential oil, which are usually obtained by batch distillation. The aim of this work was to validate a patented continuous steam distillation process and to both physically and chemically characterize the volatile fractions of essential Persian lime oil. Prior to distillation, lime juice was obtained by pressing the lime fruit. Afterwards, the juice was subjected to a continuous steam distillation process by varying the ratio of distillate flow to feed flow (0.2, 0.4, and 0.6). The distillate oil fractions were characterized by measuring their density, optical rotation, and refractive index. Gas chromatography GC-FID was used to analyze the chemical compositions of the oil fractions. The process of continuous steam distillation presented high oil recovery efficiencies (up to 90%) and lower steam consumption compared to traditional batch process distillation since steam consumption ranged from 32 to 60% for different steam levels. Moreover, a reduction in process time was observed (from 8 to 4 h). The oil fractions obtained via continuous steam distillation differed significantly in their composition from the parent compounds and the fractions.     

Polyhedral oligomeric silsesquioxane (POSS) reinforced-unsaturated polyester hybrid nanocomposites: Thermal,thermomechanical and morphological properties

Unsaturated polyester (UP)-POSS hybrid nanocomposites have been developed successfully through the reaction between maleimide groups Octa (maleimido phenyl) silsesquioxane (OMPS) and olefinic reactive sites (maleimide and styrenic units) present in the unsaturated polyester resin system through free radical polymerization using benzoyl peroxide (BP) as the initiator. The hybrid molecular structure of nanocomposites resulted was evaluated by FT-IR spectroscopy. The data obtained from XRD, SEM and TEM analysis ascertain the presence of homogeneous morphology and nanoscale dispersion of OMPS into the polyester hybrid nanocomposites. Data resulted from thermal (DSC and TGA) and thermo-mechanical (DMA) studies indicated that the incorporation of octamaleimide functionalized POSS into unsaturated polyester systems appreciably improved the thermal properties of the hybrid nanocomposites according to their percentage concentration.     

不同蒸馏压力下的生物油分子蒸馏分离特性研究

采用分子蒸馏分离技术对热敏性生物油在不同蒸馏压力下的分离特性进行了研究。经过分子蒸馏分离后,生物油被分离为蒸出馏分油与残留馏分油,蒸出馏分油的得率随着压力的下降而显著增大,在700 Pa时达到了56.50%(质量分数)。在馏分油的物理性质方面,蒸出馏分油富集了生物油内的大部分水分,残留馏分油内水分得到了较好的脱除,其中,700 Pa下残留馏分油的水分含量降至4.20%(质量分数)。结合生物油及馏分油的GC-MS分析结果,对乙酸、苯酚、糠醛以及左旋葡聚糖等生物油内典型化合物在不同蒸馏压力下的分布特性进行了研究,获得了相应化合物在分子蒸馏过程中的富集规律。结合分离因子评估模型对生物油内14种代表化合物的富集特性进行了量化评价。     

含氟不饱和聚酯的合成及其抗磨性能研究(英文)

将氟原子引入不饱和聚酯链中,合成了含氟不饱和聚酯,并探索了其合成条件;采用四球摩擦磨损试验机评价了含氟不饱和聚酯在液体石蜡中作为抗磨添加剂的摩擦学性能,并利用红外光谱仪、X射线光电子能谱仪和扫描电镜分析了摩擦表面膜的结构、形貌和化学状态.结果表明,氟原子的引入有利于降低聚酯的黏度,并改善聚酯在液体石蜡中的分散性;合成产物作为抗磨添加剂可以在钢球磨损表面形成聚合物膜,从而显著提高基础油的摩擦学性能.     

Natural compounds obtained through centrifugal molecular distillation

Soybean oil deodorized distillate (SODD) is a byproduct from refining edible soybean oil; however, the deodorization process removes unsaponifiable materials, such as sterols and tocopherols. Tocopherols are highly added value materials. Molecular distillation has large potential to be used in order to concentrate tocopherols, because it uses very low levels of temperatures because of the high vacuum and short operating time for separation and, also, it does not use solvents. However, nowadays, the conventional way to recover tocopherols is carrying out chemical reactions prior to molecular distillation, making the process not so suitable to deal with natural products. The purpose of this work is to use only molecular distillation in order to recover tocopherols from SODD. Experiments were performed in the range of 140–220°C. The feed flow rate varied from 5 to 15 g/min. The objective of this study was to remove the maximum amount of free fatty acids (FFA) and, so, to increase the tocopherol concentration without add any extra component to the system. The percentage of FFA in the distillate stream of the molecular still is large at low feed flow rates and low evaporator temperatures, avoiding thermal decomposition effects.     

Steady state and dynamic simulation of a hybrid reactive separation process

Modelling and simulation of hybrid reactive separation system in steady state and in dynamic regime was carried out. The investigated hybrid process consisted of a reactive distillation column and a pervaporation membrane located in the distillate stream to remove water from the process. Heterogeneously catalysed esterification of propionic acid with propan-1-ol to propyl propionate and water was chosen as the model chemical reaction. Esterification reactions are a typical example of equilibrium-limited reactions producing water as a by-product. Using just a pervaporation membrane brings the biggest benefit in increasing the yield of one of the reactants due to the removal of water. To study reactive separation processes, a model of the hybrid system in steady state and in dynamic regime was developed. Steady state behaviour of the model was studied for different hybrid system configurations. The effect of catalyst amount doubling was also investigated. Dynamic behaviour of the system during the step changes of propionic acid feed flow rate and during the membrane module failure was investigated. For this reason, the conversion of propionic acid, purity of the product stream, mole fraction of water, and the temperature in three different parts of the reactive distillation column were monitored.     

改性聚乙二醇修饰高交联度不饱和聚酯网络结构的动态力学分析

合成了一系列含有反应活性端基的改性聚乙二醇,并用其对BMC(团状模塑料)专用的高交联度不饱和聚酯进行增韧.结果表明,含有反应性马来酸酐端基的聚乙二醇参与了不饱和聚酯的固化反应,可在交联网络中构成不同长度的柔性链段,在显著提高不饱和聚酯的韧性的同时,基本保持了材料的模量及其它力学性能.用动态力学分析(DMA)对不饱和聚酯交联网络结构进行了系统研究.     

The Influence of Structural Features on the Chemical Resistance of Unsaturated Polyester Resins

Abstract

Unsaturated polyester resins are widely used in the field of chemical process equipment [1-4] because of their handling properties. For example, large structures of complex shape can be fabricated with simple tools, frequently on the site. In general, unsaturated polyesters do not show an outstanding resistance to strong solutions of corrosive chemicals in contrast with other plastics. Nevertheless, as the chemistry of the unsaturated polyesters developed, special resins were made with excellent resistance to chemicals while maintaining important handling properties.     

Morphology and performance of unsaturated polyester nanocomposites modified with organoclay and thermoplastic polyurethane

<正>Unsaturated polyester(UPR)/thermoplastic polyurethane(TPU)/organoclay nanocomposites were prepared by melt compounding of thermoplastic polyurethane and unsaturated polyester prepolymer,and then mixing with the hybrids of styrene monomers and organoclay at ambient temperature.The crosslinking reaction eventually occurred through the unsaturated polyester prepolymer and styrene monomer.The morphology of the composites was investigated by scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the impact strength of UPR/TPU/organoclay nanocomposites increases obviously;the cure shrinkage decreases markedly,the glass transition temperature is enhanced and an elastic response to the deformation is prominent at the temperature above 10℃.     

Syntheses of functional condensation polymer. I. Polyesters having pendant functional groups such as hydroxyl,formyl, aldoxime,aminomethyl and hydroxymethyl

Unsaturated polyesters having pendant functional groups such as hydroxyl, formyl, aldoxime, aminomethyl and hydroxymethyl, have been prepared and characterized, and some of their properties were investigated. Reaction conditions for the epoxidation of unsaturated polyesters and hydrolysis of the epoxy groups in the polyesters were established to control the amount of pendant diol groups. It was possible to incorporate up to 90 mole-% of formyl side groups into the unsaturated polyester by the hydroformylation with the rhodium catalyst. In addition, the formyl side groups of the modified polyester were converted into hydroxymethyl or aldoxime groups and were then converted to amino groups. The melting points of the modified polyesters decreased with increasing the pendant group content of the polyesters, as expected. Aliphatic polyesters having pendant hydroxyl or amino groups had a high affinity for moisture, which might be ascribed to the participation of the hydrophilic pendant groups in the modified polyesters.     

高岭土对不饱和聚酯树脂的热稳定性、阻燃及力学性能的影响

不饱和聚酯树脂;高岭土;纳米复合材料;原位聚合;阻燃;成炭     

Influence of Residual Polyesterification Catalysts on the Curing of Polyesters

 Unsaturated polyesters are synthesized by means of polyesterification, often with catalysts like strong acids, metal oxides and metal-organic salts. Most often, the catalysts used cannot be separated from the bulk of the polyester. Also, some organic or inorganic additives – called fillers – which are used with the polyester in order to decrease cost, affect the curing of the polyester. In this work the effect of residual catalyst on the curing of unsaturated polyester is studied. Unsaturated polyesters were prepared using propylene glycol with a 10% molar excess over stoichiometry and a mixture of dicarboxylic acids, namely maleic acid (unsaturated) adipic acid (saturated) and phthalic anhydride (saturated) at a molar ratio 1:2:2. Lead dioxide, p-toluenesulfonic acid and zinc acetate were used as catalysts, at 0.1% w/w. After the polyesterification, the polymers were diluted with styrene at a proportion of 100:30 w/w. The resins were cured by using MEKP (methylethylketone peroxide) as initiator and CoNp (cobalt naphthenate) as accelerator. Catalysts affect the final color of the polyester. The kinetics of curing of the resins was studied by DSC analysis based on the exothermic peak due to the double bonds breaking to give crosslinked macromolecules. The heat released ΔH is decreased by the presence of catalyst, while activation energy, the frequency factor and the order of reaction are increased.     

Unsaturated Sugars : An Alternative Route to 3, 5, 6-Trideoxy-1, 2-O-Isopropylidene-α-D-Glycero-Hex-3, 5-Dienofuranose

Unsaturated sugars are among the most important and useful compounds in carbohydrate chemistry. They assume key roles in the synthesis of modified sugars and complex natural products. The title compound 5, an unsaturated sugar containing a conjugated diene system, has been reported¹ recently and its potential synthetic value for Diels-Alder reaction giving access to functionalized annulated furanoses has been pointed out.² For a different synthetic purpose we prepared this compound by an alternative route albeit from the same starting material used by the previous authors. Our synthetic sequence is outlined in the following scheme.     

Biodiesel Production from Integration Between Reaction and Separation System: Reactive Distillation Process

Biodiesel is a clean burning fuel derived from a renewable feedstock such as vegetable oil or animal fat. It is biodegradable, non-inflammable, non-toxic, and produces lesser carbon monoxide, sulfur dioxide, and unburned hydrocarbons than petroleum-based fuel. The purpose of the present work is to present an efficient process using reactive distillation columns applied to biodiesel production. Reactive distillation is the simultaneous implementation of reaction and separation within a single unit of column. Nowadays, it is appropriately called “Intensified Process”. This combined operation is especially suited for the chemical reaction limited by equilibrium constraints, since one or more of the products of the reaction are continuously separated from the reactants. This work presents the biodiesel production from soybean oil and bioethanol by reactive distillation. Different variables affect the conventional biodiesel production process such as: catalyst concentration, reaction temperature, level of agitation, ethanol/soybean oil molar ratio, reaction time, and raw material type. In this study, the experimental design was used to optimize the following process variables: the catalyst concentration (from 0.5 wt.% to 1.5 wt.%), the ethanol/soybean oil molar ratio (from 3:1 to 9:1). The reactive column reflux rate was 83 ml/min, and the reaction time was 6 min.     

Microwave-assisted continuous reactive distillation process for preparation of ethyl acetate

As a novel process intensification technology, microwave-assisted continuous reaction distillation (MRD) was proposed for the esterification reaction and separation of ethyl acetate (EtOAc). The effects of reflux ratio, mole ratio of acetic acid (HOAc) to ethanol (EtOH), reboiler duty, microwave power on EtOH conversions, EtOAc purity and mass ratio of distillate to feed (D/F) were explored. In comparison with conventional heating, the experimental results revealed that the EtOAc purity in the distillate under microwave conditions (MC) was improved. Computer simulations for conventional and MRD systems were performed using the Aspen Plus non-equilibrium stage model to substantiate the experimental results. The model predictions are in good agreement with the experimental data, revealing the accuracy and reliability of the non-equilibrium model. This new MRD process can be an effective and productive method of ester production.     

Peroxide-containing compatibilizer for polypropylene blends with other polymers

An approach to synthesize interfacial active peroxide graft copolymers, so called precompatibilizers, which are suitable for the universal compatibilization of one special polymer with a number of other polymers, has been presented. As example, this approach is illustrated by the reactive fusion of a random peroxide copolymer (VO) with polypropylene (PP) resulting in a VOgPP precompatibilizer. A mathematical model of the process of the VOgPP synthesis and the conduction of a full-factorial experiment have allowed both the optimization of the synthesis conditions and the prediction of its proceeding. During blending PP with other polymers VOgPP localizes across the blend interphases and initiates radical processes leading to the in situ formation of final compatibilizer macromolecules, which are efficient just for the blends where they are formed. The universality of the precompatibilizer concept is demonstrated in PP blends of the thermoplastic/thermoplastic type (with polystyrene and polyethylene) and of the thermoplastic/thermoset type (with unsaturated polyester resin).     

Control production of polyester resins by NIR spectroscopy

The control of the esterification reaction for production of polyester saturated resins is followed usually by determination of the acid value (AV) and hydroxyl value (OHV).These parameters are determined by titrimetry, but these methods are slow, intensity working and produce waste. In this paper an alternative methodology is proposed, based in the construction of multivariate models on NIR spectroscopic data and different models are constructed in order to apply to different steps of the production process. The ensuing methodology provides models of good predictive ability and constitute an advantageous alternative to existing titrimetric reference methods as regards expeditiousness and environmentally compatible. The multivariate calibration models established were also used with a different instrument; to this end, the spectra recorded with the original equipment were subjected to Piecewise Direct Standardization (PDS) in order to make them equivalent to those provided by the new equipment. Also, PLS calibration was reproduced by using the same samples, spectral treatment, wavenumber range and number of factors as in the original model, and the AV and OHV results thus obtained were similarly good.     

Control production of polyester resins by NIR spectroscopy

The control of the esterification reaction for production of polyester saturated resins is followed usually by determination of the acid value (AV) and hydroxyl value (OHV).These parameters are determined by titrimetry, but these methods are slow, intensity working and produce waste. In this paper an alternative methodology is proposed, based in the construction of multivariate models on NIR spectroscopic data and different models are constructed in order to apply to different steps of the production process. The ensuing methodology provides models of good predictive ability and constitute an advantageous alternative to existing titrimetric reference methods as regards expeditiousness and environmentally compatible. The multivariate calibration models established were also used with a different instrument; to this end, the spectra recorded with the original equipment were subjected to Piecewise Direct Standardization (PDS) in order to make them equivalent to those provided by the new equipment. Also, PLS calibration was reproduced by using the same samples, spectral treatment, wavenumber range and number of factors as in the original model, and the AV and OHV results thus obtained were similarly good.     

The Operable Modeling of Simultaneous Saccharification and Fermentation of Ethanol Production from Cellulose

An operable batch model of simultaneous saccharification and fermentation (SSF) for ethanol production from cellulose has been developed. The model includes four ordinary differential equations that describe the changes of cellobiose, glucose, yeast, and ethanol concentrations with respect to time. These equations were used to simulate the experimental data of the four main components in the SSF process of ethanol production from microcrystalline cellulose (Avicel PH101). The model parameters at 95% confidence intervals were determined by a MATLAB program based on the batch experimental data of the SSF. Both experimental data and model simulations showed that the cell growth was the rate-controlling step at the initial period in a series of reactions of cellulose to ethanol, and later, the conversion of cellulose to cellobiose controlled the process. The batch model was extended to the continuous and fed-batch operating models. For the continuous operation in the SSF, the ethanol productivities increased with increasing dilution rate, until a maximum value was attained, and rapidly decreased as the dilution rate approached the washout point. The model also predicted a relatively high ethanol mass for the fed-batch operation than the batch operation.     

单原子催化剂在电化学合成氨中的理论研究进展

传统Haber-Bosch工艺合成氨需要大量的能源消耗和复杂的工厂基础设备。在可再生能源的推动下,将氮气电化学还原为氨被认为是替代Haber-Bosch工艺最有效的方法,这在科学界引起了极大的关注。然而,这个过程受到氨产量和法拉第效率低的影响,因此开发更有效的电催化剂对其实际应用至关重要。在之前报告的催化剂中,单原子催化剂（SACs）在高效利用原子和不饱和配位方面表现出显著优势,这为优化催化剂性能提供了巨大的空间。文章综述了单原子催化剂在电化学合成氨中的理论研究,详细分析了贵金属催化剂、非贵金属催化剂和非金属催化剂这3类单原子催化剂的性能表现,旨在为电化学合成氨技术的发展提供理论参考。