动态法研究催化剂担体对吸附和表面反应速度常数的影响

应用动态法在常压260℃～284℃条件下获得环已烷在 SiO_2、Al_2O_3和TiO_2三种载铂催化剂上脱氢反应的吸附和表面反应速度常数。结果表明:对 Pt/TiO_2催化剂,诸动力学参数均较其它三者为低。而对 Pt/SiO_2和 Pt/Al_2O_3,虽具有相同的总包反应速度常数,但其表面反应速度常数和吸附平衡常数完全不同。在反应条件下三种催化剂上的反应均为表面反应控制。     

测定活性炭吸附苯酚的试验方法

介绍了一种测定活性炭吸附苯酚的试验方法,本方法是根据对JWWAK113标准实践的基础上,为使该标准本土化而编写的。     

测定活性炭吸附苯酚的试验方法

介绍了一种测定活性炭吸附苯酚的试验方法，本方法是根据对JWWAK 113标准实践的基础上，为使该标准本土化而编写的。     

吸附反应器的动态特性—非瞬时竞争吸附的影响

针对可逆催化反应Ａ－Ｂ＋Ｃ、各组分非瞬时Ｌａｎｇｍｕｉｒ吸附的情况，研究了固定床吸附反应器的动态特性，着重分析多组分非时竞争吸附的影响。对反应物阶跃输入时，吸附反应器的出口浓度响应进行了模拟分析，模拟结果预示，在一定的参数条件下，动态操作的吸附反应器有较高的反应转化率、高的产物和反应物分离度、而且产物Ｂ和Ｃ之间也能同时得到高度分离。另外，给出了Ｂ和Ｃ分离的条件及定性评价其分离程度的判据。     

测定活性炭吸附ABS的试验方法

介绍了一种测定活性炭吸附ABS（阴离子表面活性剂）的试验方法，笔者是在对JWWA K113标准实践的基础上，为使该标准本土化而重新编写的。     

多组分吸附过程的吸附速率模型

Three adsorption rate models are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models I and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model I is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption processes while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.     

加氢催化剂活性对吸附和表面反应速率的影响

α-甲基苯乙烯在三相浆化反应器中加氢的动态研究表明,催化剂还原温度对吸附平衡常数、吸附和表面反应速率系数有明显的影响。实验在全混浆化反应器中进行,温度为22℃,38℃和50℃,当还原温度从250℃增加到510℃时,PdCl_2还原为 Pd 的 Pd 分散度减小,从而使平衡吸附,吸附和表面反应速率系数均减小。吸附热和表面反应活化能分别为15.9和41.8KJ/mol,且不随还原温度而变。对于三个不同还原温度,其金属分散度的相对大小可从平衡吸附系数计算,发现其结果与 Boitiaux 等的实验结果一致。     

测定活性炭吸附甲苯等温线的试验方法

介绍一一种活性炭吸附甲苯的吸附等温线的试验方法     

直馏汽油动态吸附脱硫的研究

吸附法深度脱硫具有操作条件温和,投资和操作费用低,脱硫效果好,不降低汽油的辛烷值等特点。本文对已开发的脱硫吸附剂(SFCZ)用于真实汽油体系中,进行吸附平衡性能考察、吸附动态性能的测定,其平衡数据和动态数据为进一步工业应用奠定了基础。     

活性炭对实验室废水中金属铬的动态和静态吸附研究

采用活性炭吸附法处理含铬水样,在动态和静态吸附试验条件下,讨论了溶液p H、活性炭颗粒大小以及Na+、NH4+、Ca2+离子对铬去除率的影响。实验结果表明,动态吸附比静态吸附效果明显;水中Na+、NH4+、Ca2+离子对活性炭吸附铬的去除率没有明显影响;在溶液p H分别为1、3、5的情况下,p H=1时活性炭对铬的去除率最高,p H=5时活性炭对铬的去除率最低;在p H=1时,200目的活性炭动态吸附140 min时,铬的去除率可达99%。     

ENHANCEMENT OF STEADY STATE REACTION RATES THROUGH COOPERATIVE ADSORPTION†

The Elovich model for single component adsorption is extended to treat two components, especially when surface heterogeneity and interactions are present. When only surface heterogeneity is present, the resulting unique steady state is stable; also the steady state rate is decreased in comparison to the Langmuir model. When attractive forces are acting in opposition to surface heterogeneity, the resulting unique steady state displays enhanced rates. When surface heterogeneity has negligible influence, the system can exhibit triple (two stable and one unstable) steady stales. In the present case attractive interactions are present between all types of molecular pairs. However oscillations are not observed for the choice of realistic interaction parameters. In addition the stable steady slates display lower rates in comparison to the single steady state.     

A SIMPLE METHOD OF DETERMINING PORE AND SURFACE DIFFUSIVITIES IN ADSORPTION STUDIES

In this paper, a new graphical method of determining pore and surface diffusivities in adsorption systems is presented. The method involves only a simple linear plot of the inverse of half time of adsorption versus a concentration factor. The pore diffusivity and the surface diffusivity are determined directly from the intercept and the slope of the straight line, respectively. Experimental data of n-butane on Ajax activated carbon are used to illustrate the potential application of this new technique in the diffusivity parameter determination.     

TRANSIENT ADSORPTION BY USE OF THE DYNAMIC BALANCE METHOD

A jet-stirred chamber is combined with the dynamic-balance technique to provide direct adsorption data. In this approach, adsorbate species are maintained at constant gas-phase levels, and adsorption rates are determined by monitoring the rate of addition of adsorbate species required to maintain preset gas-phase concentrations.     

INFLUENCE OF CHAR PROPERTIES ON REACTION RATES

The reaction of coal char is affected by the char morphology, which is dependent on the temperature and pressure at which the char is prepared. Char properties, such as surface area (by CO₂ adsorption) and diffusion coefficients of CO₂ in char have been measured for chars prepared at 900-1200°C and at pressure to 16 atm at 900°C. The diffusion coefficient results strongly indicate Knudsen or activated surface diffusion. The surface areas and diffusion coefficients decrease in general at higher preparation temperatures, but have a maximum at 1000°C. There is an apparent relationship between these observations and the reactivity results which demonstrate unusual behavior above 1000°C.     

INFLUENCE OF CHAR PROPERTIES ON REACTION RATES

The reaction of coal char is affected by the char morphology, which is dependent on the temperature and pressure at which the char is prepared. Char properties, such as surface area (by CO₂ adsorption) and diffusion coefficients of CO₂ in char have been measured for chars prepared at 900-1200°C and at pressure to 16 atm at 900°C. The diffusion coefficient results strongly indicate Knudsen or activated surface diffusion. The surface areas and diffusion coefficients decrease in general at higher preparation temperatures, but have a maximum at 1000°C. There is an apparent relationship between these observations and the reactivity results which demonstrate unusual behavior above 1000°C.     

ON THE ASYMMETRY OF ADSORPTION AND DESORPTION IN MICROPOROUS SOLIDS

We have presented in this paper a theory to explain the asymmetry of the adsorption curve and the desorption curve in microporous solids by taking into account the surface mass action process at the pore mouth of the micropore. Effects of concentration and temperature are particularly investigated. The difference between the activation energy for desorption and that for micropore diffusion has been found to have a strong effect on this asymmetry.     

ADSORPTION AND WETTING PROPERTIES OF PLURONIC BLOCK COPOLYMERS ON HYDROPHOBIC SURFACES STUDIED BY OPTICAL WAVEGUIDE LIGHTMODE SPECTROSCOPY AND DYNAMIC TENSIOMETRIC METHOD

Adsorption of four different poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymers (Pluronics®) onto the hydrophobized surface of the sensor was measured by the optical waveguide lightmode spectroscopy (OWLS). Adsorbed amounts of Pluronic PE10300, PE10500, PE6400, and PE6800 determined in the concentration range of 10^-2-10 gdm^-3 were found to follow the order of the hydrophobicity of the Pluronic compounds characterized by their hydrophil-lipophil balance (HLB) values. Wettability of two hydrophobic surfaces, the poly(lactide-co-glycolide), PLGA70/30 copolymer (used as drug carrier in pharmaceutical applications) and silylated glass, in aqueous solutions of the above Pluronics were studied by a dynamic tensiometric method. The significant increase in the wetting tension observed after the adsorption of the surfactants, and hence the decrease of the apparent contact angle as the indication of the wetting effect on both the biopolymer and the hydrophobic glass, was correlated to the poly(ethylene oxide) (PEO) content of the adsorbed layer obtained on the hydrophobized sensor surface by the OWLS method.     

ADSORPTION AND WETTING PROPERTIES OF PLURONIC BLOCK COPOLYMERS ON HYDROPHOBIC SURFACES STUDIED BY OPTICAL WAVEGUIDE LIGHTMODE SPECTROSCOPY AND DYNAMIC TENSIOMETRIC METHOD

Adsorption of four different poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymers (Pluronics®) onto the hydrophobized surface of the sensor was measured by the optical waveguide lightmode spectroscopy (OWLS). Adsorbed amounts of Pluronic PE10300, PE10500, PE6400, and PE6800 determined in the concentration range of 10^?2?10?gdm^?3 were found to follow the order of the hydrophobicity of the Pluronic compounds characterized by their hydrophil–lipophil balance (HLB) values. Wettability of two hydrophobic surfaces, the poly(lactide-co-glycolide), PLGA70/30 copolymer (used as drug carrier in pharmaceutical applications) and silylated glass, in aqueous solutions of the above Pluronics were studied by a dynamic tensiometric method. The significant increase in the wetting tension observed after the adsorption of the surfactants, and hence the decrease of the apparent contact angle as the indication of the wetting effect on both the biopolymer and the hydrophobic glass, was correlated to the poly(ethylene oxide) (PEO) content of the adsorbed layer obtained on the hydrophobized sensor surface by the OWLS method.