Non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends

The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry(DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature(T onset) and crystallization peak temperature(T p) decrease with the increase of the content of reactive microgel, while ΔT(T onset–T p), the crystallization half-time(t1/2) and the crystallization enthalpy(ΔH c) increase. The required cooling rates of blends are higher than that of neat nylon6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity(X t) reaches the maximum.

Recovery of carbon monoxide from flue gases by reactive absorption in ionic liquid imidazolium chlorocuprate(I): Mass transfer coefficients

Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate（l） ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with fiat gas-liquid interface. The experimental mass transfer coefficients showed significant var- iation with temperature, （3.4-10.9） × 10^-7 m·s^-1 between 293 and 313 K; stirring speed, （10.2- 33.1）× 10^-7 m.s 1 between 100 and 300 r·min^-1; and concentration of copper（1）, （6.6-10.2） × 10^-7 m·s^-1 between 0.25 and 2 mol· L^- 1. In addition, the mass transfer coefficients were eventually found to follow a poten- tial proportionality of the type kL ∝μ^-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained： Sh=10^-2.64 Re^1.07 , Sc^0.75,These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate（I） ionic liquid that determines the design of the separation units.

Kinetic studies on the dimerization of isobutene with Ni/Al_2O_3 as a catalyst for reactive distillation process

Isooctane is a promising gasoline additive that could be produced by dimerization of isobutene(IB) with subsequent hydrogenation.In this work,the dimerization of IB has been carried out in a batch reactor over a temperature range of 338-383 K in the presence of laboratory prepared Ni/Al_2O_3 as a catalyst and n-pentane as solvent.The influence of various parameters such as temperature,catalyst loading and initial concentration of IB was examined.A Langmuir-Hinshelwood kinetic model of IB dimerization was established and the parameters were estimated on the basis of the measured data.The feasibility of oligomerization of IB based on the reactive distillation was simulated in ASPEN PLUS using the kinetics developed.The simulation results showed that the catalyst of Ni/Al_2O_3 had higher selectivity to diisobutene(DIB) and slightly lower conversion of IB than ion exchange resin in the absence of polar substances.

Study of the Corrosion of High Alumina Refractories by Al_2O_3-CaO Slag as a Reactive Impregnation Mechanism

The corrosion of refractories results from reactive transport,namely,transport of agents and chemical reactions of these agents with impregnated medium. On one hand,the transport involves either diffusion or impregnation depending on the state of the corrosive agents and the microstructure of the host media. On the other hand,chemical reactions may be very numerous and complex.This study focused on the reactive impregnation of Al2O3- CaO slag into porous high alumina refractory. The transport properties of the refractory material were identified by means of a dedicated capillary rising test. Chemical reactions between the solid high alumina skeleton and Al2O3- CaO slag involve successive dissolution / precipitation mechanisms forming aluminates of lime. Contrary to the thermodynamic properties of the binary system,the kinetics of these solid / liquid reactions is not well known.Corrosion tests associated with the quenching method,XRD analyses were performed for a better understanding of the kinetics. The results of this study open up a coupling approach for predicting the corrosion wear of refractory.

Two-dimensional modeling of the self-limiting oxidation in silicon and tungsten nanowires

Self-limiting oxidation of nanowires has been previously described as a reaction- or diffusion-controlled process. In this letter, the concept of finite reactive region is introduced into a diffusion-controlled model, based upon which a two-dimensional cylindrical kinetics model is developed for the oxidation of silicon nanowires and is extended for tungsten. In the model, diffusivity is affected by the expansive oxidation reaction induced stress. The dependency of the oxidation upon curvature and temperature is modeled. Good agreement between the model predictions and available experimental data is obtained. The de- veloped model serves to quantify the oxidation in two-dimensional nanostructures and is expected to facilitate their fabrication via thermal oxidation techniques.

Self-glazing SiC-andalusite Refractories for High Temperature Gasification Applications

The combination of SiC and andalusite with calcium aluminate binder for castables in high corrosive gasifying environments is a promising alternative refractory system for many different slag systems. After sintering,a glassy protective layer has been identified. Beside the interactions of the refractories with intermediate slag also the thermomechanical properties,the thermal shock performance and the microstructure have been evaluated as a function of different binder systems.

Colloidal Silica Sol Bonded Castables for High Temperature Applications

A colloidal silica sol bonded product range is introduced by an example targeting high temperature applications in steel making. Placement and setting characteristics are shown. The thermal mechanical properties and resulting advantages are presented as well as the performance enhancement in corrosion resistance. Properties are compared to a common ULCC product. Results of the industrial trial phase are discussed.