Fullerene C60 as an inhibitor of high temperature lipid oxidation

Non-isothermal oxidation of a model saturated lipid (stearic acid) in the bulk phase in the presence of fullerene C₆₀ at concentrations of 1–8 mM was monitored by differential scanning calorimetry in order to determine the kinetic parameters that describe the global first order oxidation process. The activation energies, pre-exponential factors, and rate constants calculated by the Ozawa–Flynn–Wall method for the first detectable exothermic effect of oxidation, indicate the antioxidant behavior of C₆₀ over a wide range of temperatures that makes it a non-corrosive agent effectively increasing the oxidative stability of lubricants and biolubricants.     

甲苯液相催化氧化过程模拟与优化

Liquid-phase oxidation of toluene with air has become the main technology for producing benzoic acid in a reactor at present. Based on the kinetic model of the toluene oxidation process obtained from laboratory and mass balance of key component, a novel model is established to simulate the industrial toluene oxidation process, in which the effects of benzaldehyde and benzyl alcohol are considered and the kinetic parameters are revised by industrial data. The simulation results show that the error of benzoic acid yield is within 3.5%. Based on the simulation model, to maximize the benzoic acid yield, an optimization model is proposed to optimize the operating parameters, including toluene feed-in mass flux and temperature. The optimization result indicates that on the allowable operating conditions the maximum benzoic acid yield obtained with the reaction temperature at 167.2 C an the mass flux at 104.1 t·h^- 1 is greater than the current one, which can be used to guide industrial reactor s operation.     

Identification of the reaction network for the synthesis of adipic acid using machine learning coupling with target factor analysis

This study investigated the reaction network of the oxidation of cyclohexanone with nitric acid through machine learning (ML) model coupling with target factor analysis (TFA). Experiments for the synthesis of adipic acid (AA) were carefully designed and carried out in a microreactor system. An artificial neural network (ANN) model was applied and optimized by training on experimental data. To assess the established ANN model, a comparison between the predicted concentrations of the products and those calculated with the power law kinetic model was implemented. TFA was then performed on both the experimental data and the data simulated by ANN for identifying the candidate reactions and finding out the temperature boundaries. Based on the identification results of the reaction network, the kinetic characteristics of this oxidation process under various operational conditions were further researched through the incremental approach and simultaneous approach.     

基于EDM、PDF和FR/ED模型的煤粉燃烧过程适应性研究

还原气氛下煤粉反应过程兼具燃烧和气化的特点,是煤粉实现低氮燃烧的关键因素,合适的化学反应模型是准确模拟该过程的基础。笔者基于煤粉双锥燃烧器,对比了EDM模型、PDF模型和FR/ED模型在氧化气氛和还原气氛的模拟结果,通过与试验结果的对比验证,确定了不同反应气氛适合的化学反应模型。研究结果表明,3种模型在煤粉着火位置和逆喷传播距离的预测上存在差别,PDF模型起火点更靠近燃烧器逆喷喷口,EDM模型一次风和煤粉喷出经过一段升温过程后逐渐燃烧,FR/ED模型的升温过程更长,壁面低温区域接近前锥长度一半;使用FR/ED模型模拟时燃烧器内平均温度最高,EDM模型次之,PDF模型最低;EDM模型中未考虑CO反应,燃烧器内基本无CO存在,PDF模型高CO浓度区域集中在煤粉燃烧初期,燃烧器出口CO含量较低,FR/ED模型化学反应动力学参数在煤粉燃烧整个区域内均有较高CO浓度存在。由于考虑了焦炭与氧气气化反应的影响,FR/ED模型模拟燃烧器内氧含量明显低于EDM和PDF模型,当过量空气系数为1.2时,燃烧器出口处氧含量为7.0%,明显低于EDM模型的11.1%和PDF模型的12.0%,燃烧器出口处CO含量为3.5%,明显高于EDM(0)和PDF模型(0.8%);过量空气系数为0.5时,EDM模型对CO成分的预测结果偏差较大,燃烧器出口CO浓度为0.05%,采用PDF和FR/ED模型时燃烧器出口CO含量分别为5.73%和10.7%。从模拟结果与试验结果的对比来看,在氧化气氛下,主要发生煤粉的燃烧反应,EDM模型和PDF模型在温度、CO含量上的预测较为准确,与试验数据偏差较小,FR/ED模型偏差较大;在还原性气氛下,EDM模型模拟的结果几乎不生成CO和H2,并不适合还原性气氛,PDF模型和FR/ED模型有较合理的还原气氛模拟结果,两者的差别在于还原性气体的生成位置,PDF模型喷口位置CO浓度较高,出口浓度偏低,FR/ED模型随着煤粉反应流程的进行,CO浓度逐渐升高,出口浓度更接近试验结果。综合考虑,氧化气氛下双锥燃烧器适合采用EDM模型和PDF模型进行模拟,还原气氛下适合采用FR/ED模型进行模拟。     

不同润滑剂对PP/POE性能的影响

研究了不同润滑剂对PP／POE（聚丙烯／聚烯烃弹性体）性能的影响。结果表明，硬脂酸类润滑剂对PP／POE的拉伸强度影响不大，硬酯酸盐类润滑剂对PP／POE冲击强度影响不大。硬脂酸类以及非硬脂酸类润滑剂对PP／POE的弯曲模量、热变形温度均有一定的影响。润滑剂一定程度上提高了PP／POE的加工性能，润滑剂在静态以及动态的加工条件下起到的作用是不同的。硬脂酸盐类有利于PP／POE的结晶。     

Comparison of oxidation induction time measurements with values derived from oxidation induction temperature measurements for EPDM and XLPE polymers

Oxidative stability and retained operational utility of polymers used as insulation for electrical cables, such as ethylene propylene diene monomer (EPDM) and crosslinked polyethylene (XLPE), may be assessed by oxidation induction time (OIT) analysis. OIT is measured directly with a differential scanning calorimeter. Using a simplified kinetics model, Gimzewski demonstrated that it is possible to calculate the OIT from measured values of oxidation induction temperature and the activation energy for petroleum lubricants. In the present research, directly measured OITs are compared with OITs calculated from measured oxidation induction temperatures and activation energies for EPDM and XLPE cable insulation. Good agreement between the two methods was demonstrated for these materials.     

液相氧化反应失控过程的动态流程模拟

随着化工工业现代化、绿色化概念的普及,氧化工艺特别是新型氧化工艺在当前工艺中所占比重日益增加,但氧化反应多为强放热反应,反应所涉及的物料往往也具有不稳定性. 为防止反应安全事故的发生,有必要进行系统的反应安全性研究. 针对液相氧化反应,本工作利用流程模拟手段,建立了带控制条件的半间歇动态反应器模型. 介绍了反应器模型的结构、传热设置和工艺控制设置方案. 选择丙烯环氧化反应开展了模拟研究,设置了相关的动力学参数和反应器参数. 通过模拟正常反应过程对设计的反应器参数进行核算,证明在正常工艺条件下可保证反应平稳进行. 利用所建立的模型模拟了密闭绝热、冷却失效和冷却水调节阀故障条件下的多场景反应危险性,得到了各场景下反应器温度、压力和反应器内物料组成的变化曲线,为后续工作中制定合理的安全控制措施提供数据支持.     

Chemical modification of vegetable oils for lubricant applications

Owing to the unfavorable impact on the environment of mineral oil-based lubricants, there has been a steady increase in the demand for biodegradable, environment-friendly lubricants. However, development of a biodegradable base fluid that could replace or partially substitute conventional mineral oil is a big challenge. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment-friendly lubricants. Vegetble oils have excellent lubricity, but poor oxidation and low-temeprature stability. This paper presents a series of structural modifications of vegetable oils using anhydrides of different chain lengths. The reaction was monitored and products were confirmed by NMR, FTIR, gel permeation chromatography, and thermogravimetric analysis (TGA). Experimental conditions were optimized for research quantity and for laboratory scale-up (up to 4 lb=1.8 kg). The thermo-oxidation stability of these new lubricant base fluids was tested using pressure differential scanning calorimetry and TGA. The chemically modified base fluids exhibit superior oxidation stability in comparison with unmodified vegetable oils. These base fluids in combination with suitable additives exhibit equivalent oxidation stability compared with mineral oil-based formulations.     

Numerical modeling of mass transfer processes coupling with reaction for the design of the ozone oxidation treatment of wastewater

A computational model for an ozone oxidation column reactor used in dyeing wastewater treatment is proposed to represent, simulate, and predict the ozone bubble process. Considering the hydrodynamics, mass transfer, and ozone oxidation reaction, coupling modeling can more realistically calculate the ozone oxidation bubble process than the splitting methods proposed in previous research. The modeling is validated and shows great consistency with experimental data. The verified model is used to analyze the effect of operating conditions, such as the initial gas velocity and the ozone concentration, and structural conditions, such as multiple gas inlets. The ozone consumption is influenced by the gas velocity and the initial ozone concentration. The ozone’s utilization decreases with the increasing gas velocity while nearly the same at different initial ozone concentrations. Simulation results can be used in guiding the practical operation of dyeing wastewater treatment and in other ozonation systems with known rate constants in wastewater treatment.     

Neural network-based hybrid models developed for free radical polymerization of styrene

In the present work, the free radical polymerization of styrene is modeled by considering the phenomenology of the process (a simplified model, which does not include the diffusional effects, gel, and glass effects) in combination with an empirical model represented by an artificial neural network. Differential evolution (DE) algorithm, belonging to the class of evolutionary algorithms, is applied for developing the neural models in optimal forms. For improving the results—predicted conversion and molecular weights as function of time, temperature, and initiator concentration—different combinations between phenomenological model and neural network are tested; also, individual and stacked neural networks have been developed for the polymerization process. This methodology based on hybrid models, including neural networks aggregated in stacks, provides accurate results.     

Design and control of a p-xylene oxidation process

The p-xylene (PX) oxidation process is of great industrial importance because of the strong demand of the global polyester fiber. A steady-state model of the PX oxidation has been studied by many researchers. In our previous work, a novel industrial p-xylene oxidation reactor model using the free radical mechanism based kinetics has been developed. However, the disturbances such as production rate change, feed composition variability and reactor temperature changes widely exist in the industry process. In this paper, dynamic simulation of the PX oxidation reactorwas designed by Aspen Dynamics and used to develop an effective plantwide control structure, which was capable of effectively handling the disturbances in the load and the temperature of the reactor. Step responses of the control structure to the disturbances were shown and served as the foundation of the smooth operation and advanced control strategy of this process in our future work.     

Influence of Additives in Adhesion of UV Radiation Surface-Treated SBS Rubber

In this study, the effect of additives (oils, lubricants) included in the formulations of different block styrene-butadiene-styrene (SBS) rubbers on the effectiveness of the ultraviolet (UV) radiation treatment to improve adhesion to polyurethane adhesive was analyzed. The modifications on the UV-treated rubber surfaces for different lengths of treatment have been characterized by contact-angle measurements (ethylene glycol, 25°C), Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). The adhesion properties have been evaluated from T-peel strengths of treated rubber/polyurethane adhesive/leather joints. The UV-radiation treatment on all rubber surfaces produced an increase in wettability, carbon-oxygen polar moieties, and ablation. The oxidation degree produced on the rubber surface treated with UV radiation was less when oils and lubricants were included in the formulation, likely due to competition of the oxidation process with the migration of low-molecular-weight additives to the rubber surface. On the SBS2 rubber surface (rubber containing carbon black and calcium carbonate fillers), the migration of oils and lubricants was also produced during the UV-radiation treatment, but a decrease in adhesion occured likely due to the lower tensile strength and higher extent of oxidation produced by the UV radiation treatment.     

Influence of Additives in Adhesion of UV Radiation Surface-Treated SBS Rubber

In this study, the effect of additives (oils, lubricants) included in the formulations of different block styrene–butadiene–styrene (SBS) rubbers on the effectiveness of the ultraviolet (UV) radiation treatment to improve adhesion to polyurethane adhesive was analyzed. The modifications on the UV-treated rubber surfaces for different lengths of treatment have been characterized by contact-angle measurements (ethylene glycol, 25°C), Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). The adhesion properties have been evaluated from T-peel strengths of treated rubber/polyurethane adhesive/leather joints. The UV-radiation treatment on all rubber surfaces produced an increase in wettability, carbon–oxygen polar moieties, and ablation. The oxidation degree produced on the rubber surface treated with UV radiation was less when oils and lubricants were included in the formulation, likely due to competition of the oxidation process with the migration of low-molecular-weight additives to the rubber surface. On the SBS2 rubber surface (rubber containing carbon black and calcium carbonate fillers), the migration of oils and lubricants was also produced during the UV-radiation treatment, but a decrease in adhesion occured likely due to the lower tensile strength and higher extent of oxidation produced by the UV radiation treatment.     

高压玻璃钢管道芯模温度预测研究

采用RBF神经网络对固化工艺中缠绕速率、芯模温度和管道外表面温度之间的关系建立模型。采用有限元数值模拟方法对模型进行训练，将训练好的模型用于不同缠绕速率和期望外表面温度下的芯模温度预测。结果表明，采用该方法设计的加温历程可使玻璃钢管道外表面温度控制在期望的范围内。本研究不仅为降低实验成本、提高生产效率提供有效方法，而且为基于理论分析的工艺参数确定和优化提供依据。     

环氧生物质油在合成润滑油基础油的研究进展

衍生于植物油和动物脂肪的生物质油是生物润滑油的重要原料。与矿物油相比,生物质油具有低毒性、高生物降解性、高润滑性和良好的黏温性等优点,但其含双键和甘油酯基导致低温流动性和氧化稳定性差。因此,生物质油不宜直接作为润滑油基础油使用。生物质油经环氧化改性增加了氧化稳定性,加强了对金属表面的吸附,提高了润滑性。但是,单纯进行环氧化改性,也会导致油品的黏温性和低温流动性变差。因此,需要对环氧生物质油进一步开环改性。对比选择性氢化、异构化等改性方法,环氧化-开环方法反应条件温和,分子设计空间大。本文总结了由环氧植物油通过开环醚构化、酰化合成生物基础油的现状和发展趋势, 重点阐述了环氧植物油及其衍生物环氧脂肪酸甲酯与有机醇、羧酸和酸酐合成润滑油的研究进展,分析了改性分子结构对润滑油性能的影响,讨论了合成生物润滑油研究中尚存的问题, 并认为优化改性工艺、开发绿色高效的催化剂是未来的发展方向。     

气体在水中的分子动力学模拟

采用分子动力学（ＭＤ）模拟的方法在常温及工业应用背景条件下对ＣＨ４、ＮＨ３、ＣＯ２、Ｏ２这些气体在水中的结构及扩散情形进行了研究。ＭＤ模拟可以为这些涉及到气体在水中的工业应用情形的机理提供分子水平的解释,同时ＭＤ模拟还可为一些不易实验测定扩散性质的体系提供工程初步设计和过程开发所需的数据。     

New approach to evaluate the influence of compressive stress on the oxidation of non-oxide ceramics

The oxidation process of non-oxide ceramics (NOCs) is accompanied with the formation of the compressive stress generated within the oxide film, which in turn affects the oxidation behavior. To shed light on the influence of the compressive stress, a modified model combining the stress equilibrium equation and RPP model has been herein proposed. This modified model can not only quantify the effect of stress evolution on the oxidation process but also accurately describe the relationship between oxidation fraction and other factors including time and temperature, etc. The comparison between experimental data and theoretical calculations for the oxidation of different NOCs verifies the validity of the modified model. It is predictable that this modified model can be applied to treat the oxidation behavior of different NOCs with the consideration of compressive stress.     

焦炉煤气制合成气反应器数值模拟

采用CFD软件F luent模拟计算焦炉煤气(COG)非催化局部氧化制合成气反应器,其中湍流模型选择标准k-ε模型,热辐射选择P-1模型,用非预混模型计算化学输运和反应。反应器内组分与温度场的数值模拟结果与实验测定结果基本吻合,说明模拟结果是可信的。通过模拟可预测,当氧气与焦炉煤气进气体积比达到0.14左右时,可以获得最好的焦炉煤气的转化效果。本数值模拟可为COG非催化局部氧化制合成气进一步的工程研究与应用提供可靠的理论参考依据。     

甲苯液相氧化反应过程的模拟

甲苯液相空气氧化是环境友好的苯甲酸和苯甲醛生产工艺。根据在模拟工业条件下测定的动力学数据和观察到的实验现象,提出了该反应的反应机理和反应网络,建立了相应的动力学模型。根据该动力学方程,对现有工业生产过程进行了模拟,发现现有工业过程处于严重供氧不足的情况。提出了3种强化方案并分别对其进行了模拟计算和比较。模拟结果表明,通过增大空气供给量和采用富氧空气氧化均可有效强化现有工业生产过程。采用富氧空气氧化,其甲苯转化率可提高到22.24%,甲苯反应量可增大57%。采用增大空气量的方法,可提高甲苯反应量31%,甲苯转化率可提高到18.61%。若同时增大甲苯和空气负荷,甲苯反应量可提高71%。     

Prediction of BP neural network and preliminary application for suppression of low-temperature oxidation of coal stockpiles by pulverized coal covering

We have developed a new method to suppress spontaneous combustion of coal piles by covering the surface of coal piles with pulverized coal. Experimental studies of three type of coal samples from China (YJL, CYW, and SW) with particle size ratio of 10:1 were performed to investigate the low-temperature oxidation of coal pillars. In this work, we have also demonstrated that the distributions of oxygen concentration, the temperature field, as well as the spontaneous combustion of three typical Chinese coal samples can be predicted accurately using back-propagation neural network (BPNN) by MATLAB. Pearson correlation analysis showed that temperature and oxygen concentration highly depend on the ratio of pulverized coal thickness to coal piles thickness, activation energy, void ratio, wind speed, and low-temperature oxidation time. Three-layer BPNN models with five input factors were developed to predict the low-temperature oxidation process under pulverized coal. The prediction data of BPNN are fitting better with our experimental data, which confirms that BPNN modelling can accurately predict the low temperature oxidation process of coal.