合成甲醇基元过程瞬态动力学的模型化(Ⅰ)——基元过程序列结构

采用动态原位红外测试技术和TPD、TPSR方法,系统地研究了合成甲醇有关物种H_2、CO、CO_2和CH_3OH在铜基催化剂上的吸附与反应特性,判识了反应过程中在催化剂活性表面上的吸附态中间物的类型。在实验信息的基础上,提出了在催化剂活性表面上可能的基元过程序列结构。

含有多价阳离子的潜影形成的基元过程

引言作者在前一篇文章中已讨论了不含多价阳离子杂质的AgBr微晶,在吸收能量小于3eV的光子后形成潜影的基元过程。采用的理论模型中,Ag_2、Ag_2O和Ag_2S分子提供给体中心,并且在未灰化和未曝光的颗粒中没有任何受体中心。在给体中心。

基元化学过程的分子束研究

前言化学是研究物质转化的科学。然而,关于化学变化的速率或时间依赖性的知识对于成功地合成新物质和利用反应所产生的能量仍然是十分重要的。在上一世纪里大家已认识到,所有的宏观化学过程都由许多基元化学反应所组成,而基元反应本身则是原子或分子物种间一系列简单的碰撞。

质量作用定律与基元反应概念辨析

质量作用定律适用于所有的基元过程。基元过程是只被一个能峰隔开的两个相邻的有一定稳定性的状态之间的变化。能峰可高可低,最低时为0。基元过程既可以是发生化学变化的基元反应,也可以是简单的物理变化。

基元反应定义的讨论

本文通过对目前流行的各种基元反应定义的分析和比较,提出一个较确切的基元反应的新定义;同时还对基元反应与基元过程进行了区分。

Molecular Dynamic Simulation on the Absorbing Process of Isolating and Coating of α-olefin Drag Reducing Polymer

The absorbing process in isolating and coating process of α-olefin drag reducing polymer was studied by molecular dynamic simulation method, on basis of coating theory of α-olefin drag reducing polymer particles with polyurethane as coating material. The distributions of sodium laurate, sodium dodeeyl sulfate, and sodium dodeeyl benzene sulfonate on the surface of α-olefin drag reducing polymer particles were almost the same, but the bending degrees of them were obviously different. The bending degree of SLA molecules was greater than those of the other two surfactant molecules. Simulation results of absorbing and accumulating structure showed that, though hydrophobie properties of surfactant molecules were almost the same, water density around long chain sulfonate sodium was bigger than that around alkyl sulfate sodium. This property goes against useful absorbing and accumulating on the surface of α-olefin drag reducing polymer particles; simulation results of interactions of different surfactant and multiple hydroxyl compounds on surface of particles showed that, interactions of different surfaetant and one kind of multiple hydroxyl compound were similar to those of one kind of surfaetant and different multiple hydroxyl compounds. These two contrast types of interactions also exhibited the differences of absorbing distribution and closing degrees to surface of particles. The sequence of closing degrees was derived from simulation; control step of addition polymerization interaction in coating process was absorbing mass transfer process, so the more closed to surface of particle the multiple hydroxyl compounds were, the easier interactions With isoeyanate were. Simulation results represented the compatibility relationship between surfactant and multiple hydroxyl compounds. The isolating and coating processes of α-olefin drag reducing polymer were further understood on molecule and atom level through above simulation research, and based on the simulation, a referenced theoretical basis was provided for practical optimal selection and experimental preparation of α-olefin drag reducing polymer particles suspension isolation agent.

Damage prediction for magnesium matrix composites formed by liquid-solid extrusion process based on finite element simulation

A damage prediction method based on FE simulation was proposed to predict the occurrence of hot shortness crocks and surface cracks in liquid-solid extrusion process. This method integrated the critical temperature criterion and Cockcroft ＆ Latham ductile damage model, which were used to predict the initiation of hot shortness cracks and surface cracks of products, respectively. A coupling simulation of deformation with heat transfer as well as ductile damage was carried out to investigate the effect of extrusion temperature and extrusion speed on the damage behavior of Csf/AZ91D composites. It is concluded that the semisolid zone moves gradually toward deformation zone with the punch descending. The amplitude of the temperature rise at the exit of die from the initial billet temperature increases with the increase of extrusion speed during steady-state extrusion at a given punch displacement. In order to prevent the surface temperature of products beyond the incipient melting temperature of composites, the critical extrusion speed is decreased with the increase of extrusion temperature, otherwise the hot shortness cracks will occur. The maximum damage values increase with increasing extrusion speed or extrusion temperature. Theoretical results obtained by the Deform^TM-2D simulation agree well with the experiments.

Unveiling the highly disordered NbO_(6) units as electron‐transfer sites in Nb_(2)O_(5) photocatalysis with N‐hydroxyphthalimide under visible light irradiation

Although different NbO_(x) units are present in Nb_(2)O_(5)‐based catalysts,the correlations between these structures and activity remain unclear,which considerably hinders the further development of Nb_(2)O_(5) photocatalysis.Herein,we utilized N‐hydroxyphthalimide(NHPI)as the probe molecule to distinguish the role of different NbO_(x) units in the activation of C–H bond under visible light irradia‐tion.With the addition of NHPI,Nb_(2)O_(5) catalysts with highly disordered NbO_(6) units exhibited higher activities than that with slightly disordered NbO_(6) units(419‒495 vs.82μmol·g^(-1)·h^(-1))in photocata‐lytic selective oxidation of ethylbenzene.Revealed by Raman spectra,electron paramagnetic reso‐nance spectra,and transmission‐electron‐microscopy images,highly disordered NbO_(6) units were confirmed to act as the active sites for the transfer of photogenerated electrons from NHPI,pro‐moting the generation of phthalimide‐N‐oxyl(PINO)radicals for the enhanced conversion of ethylbenzene under visible light irradiation.This study provides guidance on the role of local NbO_(x) units in Nb_(2)O_(5) photocatalysis.

核-核碰撞间歇现象的混合效应

通过对核－核碰撞中归一化阶乘矩反常标度性的一些实验结果的观察，发现在末态高维相空间中，阶乘矩和空间分割数的双对数图呈急剧上翘的现象。经过仔细分析，用核－核碰撞是许多基元碰撞混合叠加的观点，对上述现象进行了定性的解释。基于这一观点，建立了一个随机级联模型，用ＭｏｎｔｅＣａｒｌｏ方法给出了与实验现象的定性符合，讨论了这一结果的可能的应用。