二乙苯溶液中C_8芳烃的吸附动力学性质

本文以连续流动单管实验装置,研究了C_8芳烃的单溶质在二乙苯溶液中的液相吸附动力学性质.测定了在170℃下对二甲苯、邻二甲苯、乙苯在二乙苯溶液中各系统的穿透曲线.根据穿透曲线以及有关的参数,分析和计算了在二乙苯溶液中C_8芳烃吸附的一些性质.并且研究和确定了本系统的吸附控制机理.     

固定床吸附分离C_8芳烃的数学模型

以自制和进口Y型合成沸石在室温下液相吸附分离对二甲苯-乙苯二元体系,研究固定床吸附分离C_8芳烃的数学模型.数模中的传质速率方程用总传质系数表征其传质特点,结合相平衡和物料衡算方程,进行数值积分,得到的理论透过曲线与实验曲线相近.为了进一步探索吸附过程动力学和传质机理,对液相控制、固相控制和固液相联合控制三种数学模型进行了初步探索和比较,发现固相控制模型更适合本研究体系.     

烷烃中少量芳烃的固定床和模拟移动床吸附

在实验研究烷烃中少量芳烃的固定床吸附动态过程和模拟移动床吸附动态过程的基础上,用固定床和模拟移动床线性推动力模型进行了模拟计算,可得到如下结论:在本文的实验条件下,固定床吸附动态模型和模拟移动床吸附动态模型拟合的结果均与实验值相符;但从技术性能指标和技术经济指标两个角度都反映出对脱除烷烃中的少量芳烃的吸附分离过程,用固定床吸附过程比模拟移动床吸附过程更具有可行性。这些结果为在直链烷基苯的生产过程中,降低循环烷烃中芳构化物的含量,实现延长脱氢催化剂的寿命,提高烷基苯的产量提供了技术基础。     

二乙苯溶液中C_8芳烃的吸附平衡

本文以连续流动单管的实验装置,研究了C_8芳烃的单溶质和双溶质在二乙苯溶液中的液相吸附平衡.从测定穿透曲线出发,作出了对二甲苯、邻二甲苯、乙苯、对二甲苯-邻二甲苯等系统在170℃下的吸附等温线.发现当溶质浓度<3.0mo1/1时,吸附等温线符合Henry定津,且双溶质溶液的吸附量可按Radke-Praus Nitz的二维理想稀溶液理论由单溶质吸附等温线进行预测.将Polanyi吸附势理论延伸应用于C_8芳烃的液相吸附.用170℃下pX-DEB系统的吸附平衡数据作出特性曲线,可预测110℃下pX-DEB系统的吸附等温线.并用动态法测定的数据,验证了上述推导.     

甲醇制丙烯的复杂反应网络和动力学模型

采用微型固定床反应器全面研究了甲醇制丙烯(MTP)反应过程,考察了甲醇单独进料、不同烯烃单独进料、甲醇和烯烃混合进料三种条件下的反应规律。结果表明,在工业H-ZSM-5催化剂上甲醇主要发生甲基化和裂解反应,C_2~C_5烯烃主要发生叠合-裂化反应,C_6和C_7烯烃主要发生裂解反应,甲醇通过一系列甲基化和烯烃裂化路径转化为丙烯,生成丙烯的反应步骤都是快反应,而甲醇裂化、乙烯转化和生成烷烃及芳烃的副反应都是慢反应。提出了MTP的复杂反应网络与动力学模型,通过实验数据的拟合获得了各步反应的动力学参数,其中甲醇甲基化和裂解反应的表观活化能大于零,烯烃叠合-裂化的表观活化能小于零,是裂化吸热反应与表面吸附放热耦合作用的结果。     

吸附法脱除烷烃中少量芳烃工业可行性分析

在实验研究烷烃中少量芳烃的吸附动态过程的基础上,确定该吸附净化过程的吸附一再生条件,探讨该过程实现的可行性,得到如下结论：从技术性能和技术经济这两个指标出发,对脱除循环烷烃中的少量芳烃的吸附分离过程,用固定床吸附过程来实现比用模拟移动床吸附过程来实现更具可行性,吸附法脱除循环烷烃中的少量芳烃具有设备投资少,能耗低的特点,有可能成为一种替代现行脱除少量芳烃的工艺方法,这些结果为在直链烷基苯的生产过程中,降低循环烷烃中芳构化物的含量,实现延长脱氢催化剂的寿命,提高烷基苯的产量提供了技术基础。     

制取高辛烷值汽油的综合流程

吸附与工业层析法相结合是从石油馏份和气体冷凝液中制取高辛烷值汽油的有效方法之一。如果这些馏份主要由直链和异链烷烃组成,靠C_5—C_8正烷烃窄馏份的吸附分离,则汽油的产率会大大地下降。虽然未吸附馏份主要由异烷烃和芳烃组成,但反应效率整个是低的。为了提高高辛烷值汽油的产率,在吸附一层析法放大试验装置上装有吸附分离正烷烃的     

模拟移动床吸附分离碳八芳烃过程的研究方法

综述了借助计算机辅助模拟技术研究碳八芳烃吸附分离过程的方法的重要意义,概括了目前模拟移动床吸附分离碳八芳烃过程的建模与优化方法,总结了建立模型的基础理论和关键参数的获取方法,归纳了分离过程中工艺操作参数和配套设备的优化方法。     

C_8芳烃在SKI-400-40催化剂上的临氢异构化反应动力学

利用固定床积分反应实验装置,在反应温度为365～410℃、空速为4～128 h~(-1)、氢烃物质的量比为3.8、反应压力为1.1 MPa条件下,对C_8芳烃在SKI-400-40催化剂上的临氢异构化宏观反应动力学进行了研究。采用六组分拟一级异构化反应网络,建立了C_8芳烃临氢异构化的宏观反应动力学模型,模型计算值与实验值吻合良好。得到的反应速率常数表明,二甲苯和乙苯间的转化可通过两种方式,一是两者之间的直接转化,二是两者通过C_8N+P的桥接转化,其中第二种方式的贡献更大。     

柱[6]芳烃的合成及最新应用进展

柱芳烃作为一类新的大环芳烃主体化合物在主-客体化学中扮演着越来越重要的角色.作为柱芳烃家族中一员,柱[6]芳烃因其简便的合成、较大的柱状空腔和优秀的主-客体性质在吸附材料、药物传递、两亲性材料等领域展示了极好的应用前景.该文着重介绍了柱[6]芳烃的分子结构、合成策略、功能化、主-客体性质及其最新的应用研究进展.     

吸附法回收废水中柠檬酸的传质机理研究

用静态实验筛选出的大孔吸附树脂ＡＢ－８在固定床内对吸附法回收柠檬酸的动态过程进行了研究。通过对包含轴向扩散的动力学模型的计算求得总传质系数，并结合由经验式得出的淮膜传质系地出该传质过程属内扩散控制，并通过实验得到验证。     

Study of Adsorption Equilibrium and Dynamics of Benzene,Toluene, and Xylene on Zeolite NaY

The equilibrium and dynamics of low concentrations of benzene, toluene, and xylene in heptane adsorbed by zeolite NaY at 30, 40, and 50 °C were studied. The Langmuir equation was suggested to simulate the isotherms. Based on isotherms and material balances, multi‐component competitive adsorption isotherms can be successfully predicted by mono‐component adsorption isotherm parameters. A series of column adsorption experiments were conducted to study the adsorption dynamics. The mass transfer equations were solved by numerical analysis and used to describe the breakthrough curves, and the mass transfer coefficients in the adsorption column were obtained as well.     

Simulation and validation of ethanol removal from water in an adsorption packed bed: Isotherm and mass transfer parameter determination in batch studies

Preferential adsorption of ethanol from ethanol/water mixtures in batch equilibrium and kinetic experiments were carried out on a commercially available activated carbon adsorbent Filtrasorb 600 (F‐600). A model based on finite difference method was developed and employed to determine the mass transfer parameters and equilibrium behaviour for the adsorption of ethanol from simple batch systems. The estimates of the adsorption isotherm along with the mass transfer parameters were used to simulate the transient performance that could be expected in a packed bed under various operating conditions (feed flow rate, feed concentration, and particle size). The applicability of the simulation results were found to be a good match with experimental packed bed experiments over the entire range of operating conditions tested.     

Thermal waves in an adsorption column: Parameter estimation

Adsorption experiments were carried out with a column packed with activated carbon particles, subject to a step input of carbon dioxide at the column inlet. From the measurements of a thermal wave advancing in the column the adsorption equilibrium constant, heat of adsorption and overall heat transfer coefficient were determined. Theoretical parameter sensitivity test also indicates that the adsorption equilibrium constant, heat of adsorption and overall heat transfer coefficient are the parameters of significance in this non-isothermal adsorption system. Discussion is also given on a heat generation and loss balance condition.     

基于矩法和时间域分析法研究稠密CO2中甲苯和对氯苯在硅胶固定床系统中的吸附和传递性质

Based on chromatographic theory, the moment method and the time-domain fitting analysis were applied to measure and evaluate the adsorption equilibrium constant and mass transfer properties (axial dispersion coefficient and effective intra-particle diffusivity) for toluene and p-dichlorobenzene on silica gel adsorbent in the subcritical and supercritical CO2. An apparatus based on supercritical fluid chromatography was established and the experiments were performed at temperatures of 298.15-318.15 K and pressures of 7.5-17.8 MPa. The two methods have been compared. The results show that for the systems studied here the moment method can give reasonable values for both adsorption equilibrium constant and mass transfer properties, but the time-domain analysis only can obtain the adsorption equilibrium constant. The dependence of adsorption equilibrium constant and mass transfer properties on temperature and pressure was investigated.     

EPA和DHA在超临界流体色谱柱中的传质动力学

用超临界流体色谱 (SFC)法研究了EPA和DHA在C18上的吸附和传质性能 .建立了色谱动力学模型并获得了模型参数 ,较好地拟合了实验流出曲线 .结果表明吸附平衡、轴向弥散、流体相传质和颗粒内有效扩散都是影响SFC分离EPA和DHA的重要因素     

Measurements of particle-to-gas mass transfer coefficients from chromatographic adsorption experiments

From chromatographic adsorption experiments, adsorption equilibrium constants and particle-to-gas mass transfer coefficients were determined by fitting tracer output signals in the time domain. The results indicate that the Sherwood numbers are far less than the limit of two for a single particle.     

红霉素在大孔树脂上的吸附动力学研究

采用液膜及孔内扩散模型,模拟不同温度和不同红霉素(EM)初始浓度条件下,大孔吸附树脂HZ816及XAD16吸附红霉素的动态吸附曲线,并获得液膜传质及孔内扩散系数;考察了温度及溶质浓度对红霉素在两种树脂中吸附动力学的影响.结果表明,在实验范围内,红霉素在HZ816和XAD16两种树脂上的吸附平衡数据满足Langmuir吸附等温线方程,液膜及孔内扩散模型能较好地描述红霉素在两种树脂上的吸附动力学,同时,模型拟合得到的液膜传质系数随着温度的升高而增大,随着初始浓度的增大而增大,孔内扩散系数随着温度的升高而增大,随着初始浓度的增大而减小.     

Adsorption of Volatile Organic Compounds on Soil and Prediction of Desorption Breakthroughs

Abstract

Vapor extraction of volatile organic compounds from soil was investigated by performing adsorption and desorption experiments of trichloroethylene, trichloroethane, and chlorobenzene on soil particles. The adsorption breakthrough curves were obtained using a dynamic response technique based on frontal analysis chromatography. The shape of the breakthrough curves indicated that the adsorption process was close to an ideal adsorption system of no mass transfer resistance, no axial dispersion, and infinitesimal width of mass transfer zone. The adsorption isotherms were BET Type I for trichloroethylene and trichloroethane, and BET Type II for chlorobenzene. Two types of desorption profiles were observed depending on the compounds, i.e., the continuously decreasing profiles of trichloroethylene and trichloroethane and the stepwise decreasing profiles of chlorobenzene. The desorption profiles of trichloroethylene and trichloroethane were simulated using a local equilibrium theory which indicated that desorption behavior was independent of the number of adsorption layers on soil. For chlorobenzene, the monolayer desorption was the rate-controlling step of the overall desorption process. The effect of moisture on desorption efficiency was significant for chlorobenzene, which showed more unfavorable desorption behavior than trichloroethylene and trichloroethane.     

ADSORPTION OF ORGANICS FROM A TRUE IN-SITU OIL SHALE RETORT WATER ON ACTIVATED CARBON IN PACKED BEDS

The adsorption of a true in-situ oil shale retort water on activated carbon at 278 and 298 K was studied in batch experiments and in packed beds with continuous liquid flow. The isotherms were nonlinear over the liquid concentration 0 to 875 mg/1. Breakthrough curves were obtained in packed bed experiments as a function of bed length, particle size, and liquid velocity. A differential approach was used to calculate the mass transfer coefficients and the rates of adsorption. Also the breakthrough curves were analyzed to establish the relative importance of the various individual mechanisms that contributed to the overall adsorption process.