合成氨铁钴催化剂还原行为的研究

本文采用热分析手段,通过程序升温还原,研究了铁触媒中加入的CoO含量和铁比对还原过程的影响规律,并对还原机理进行了初步探讨。     

制备高碳醇用Cu-Fe系催化剂的活性相

用共沉淀法制备了Ｃｕ－Ｆｅｘ系催化剂，它是由脂肪酸甲酯加氢制备高碳醇的新催化体系。催化剂经焙烧后的物相为ＣｕＯ，γＦｅ２Ｏ３和ＭｇＯ，形成了活性相的结构前驱。     

球形氨合成催化剂中钾的溶出规律

研究了球形氨合成催化剂中水溶性钾的作用及不同条件下钾的溶出速率。实验结果表明:水溶性钾的损失将导致催化剂活性的降低;在水中催化剂钾的溶出速率与催化剂的组成、外形、制造工艺、颗粒大小及水的温度和水中K_2CO_3浓度的大小有密切关系。在测定了不同催化剂样品的水溶性钾含量后,提出了球形氨合成催化剂在水中钾溶出速率方程式。求出溶出过程的活化能为4700卡/克分子。     

稀土掺杂氨合成球形催化剂的X射线衍射研究

本文用X射线衍射法考察了几种铈、钐氧化物掺杂的氨合成球形催化剂的氧化态结构,并与磁铁矿及未掺杂的A_(110)-5Q型催化剂作了比较。结果表明:不同掺杂催化剂均含有(Fe_3O_4)_(56)F相,但随稀土量增加,(Fe_3O_4)56F相衍射峰强度逐渐减弱,维氏体(Wustite)含量降低。双掺CeO_2和Sm_2O_3的催化剂(831102 SmCe)的这种现象更为明显。据此进一步探讨了铁比(Fe~(2+)/Fe~(3+))、稀土氧化物(CeO_2,Sm_2O_3)和氧化铝对氨合成催化剂结构影响的机制,提出了一些看法。     

Experimental Test of 7.8GHz Power Extractor Using Dielectric Loaded Rectangular Waveguide Structures

We report on experimental test of a 7.8 GHz power extractor using a dielectric loaded rectangular waveguide structure. This work is conducted at the Argonne wakefield accelerator （AWA） facility. The wakefield is excited by an electron beam travelling through a dielectric loaded rectangular waveguide, and the generated rf power is then subsequently extracted with a properly designed rf coupler. In the experiment, 30 MW of output power is excited by a 66nC single electron bunch, and wakefield superposition by a train consisting of four bunches is also demonstrated. Both the results agree well with theoretical predictions.     

光混合实验仪器的制作

光的混合实验是光学中较为重要的一个演示实验.为此,笔者精心制作了"光混合"实验演示仪,收到了良好的教学效果.现将仪器制作过程及操作方法简单介绍如下.     

半透膜的制作与渗析实验

渗析实验是"胶体"一节中一个很重要的实验.如何利用鸡蛋非常简单地制作半透膜袋并应用到渗析实验中呢?通过反复研究实验,发现了一种简单易行的制作方法,现介绍如下.     

Analysis of space harmonic selectivity of period-varying folded waveguide

A period-varying folded waveguide is formed by varying the period of a folded waveguide. It has the advantages of the space harmonic selectivity and the wide bandwidth. However, the regularities of the variety of these period-varying folded waveguides are unavailable from the published papers. In order to solve this problem, the principle of the space harmonic selectivity of a period-varying folded waveguide is analysed, and the conditions to select the space harmonic for this slow wave system are obtained. In addition, the space harmonic selectivities for a linear period-varying folded waveguide and a hyperbolic sine-varying period folded waveguide are also analysed as examples.     

The study of synchronization in the periodic nonuniform folded waveguide

The periodic nonuniform folded waveguides are special structures, the physical dimension of which is between the periodic folded waveguide and the tapering period folded waveguide. Therefore, the synchronization between the microwave and the electron beam can be maintained in the whole interaction process and the periods are not tapered. In comparison with the tapering period folded waveguide, the theoretical analysis and the technological requirements for this structure are more convenient. In order to study this structure, the space harmonics are analysed, the conditions to make the m-th space harmonic synchronizing with the electron beam in the whole interaction process are present, and the dispersion curve and the coupling impedance curve are obtained by the simulation software HFSS.     

7.8GHz power generation device design using a rectangular dielectric-loaded waveguide

In this paper, we present a design where a bunched relativistic electron beam traversing inside the rectangular dielectric-loaded (DL) waveguide is used as a high power microwave generation device. Two kinds of methods of calculating the electromagnetic (EM) field excited by a bunched beam are introduced, and in the second method the calculation of EM pulse length is discussed in detail. The desired operating mode is the LSM_11 due to its strong interaction with the electron beam. For the designed 7.8~GHz operating frequency, with a 100~nC/bunch drive train of electron bunches separated by 0.769~ns, we find that high gradient (>30~MV/m) and high power (>160~MW) can be generated. An output coupler is also designed which is able to extract the generated power to standard waveguides with a 94% coupling efficiency.