大孔沸石L的完全经La交换的形式La 3.0 Al 9.0 Si 27.0 O 72,是通过重复水合离子交换和煅烧产生的内部阳离子交换而制备的,以得到低硅沸石(Si / Al = 3)所有阳离子都隐藏在可用孔隙中。这是由于La 3+从大的12元环(12R)通道(可通过水溶液交换)中的位点迁移到结构中的“封闭”位点。此内部的阳离子交换,已阐明由粉末X射线衍射数据的Rietveld分析的机构,包括拉顺序3+迁移,第一到STE框架之间的斜方晶石(罐)笼之间,然后进入罐笼。在每种情况下,K +阳离子必须首先通过8Rs离开封闭的笼子,在第二种情况下通过褶皱6Rs离开第二笼。第一步迁移达到了573 K,第二步达到了1073K。沸石K 9.0 –,K 5.7 La 1.1 –,K 2.7 La 2.1 –和La 3.0 –L的可及主通道位点上的K +占有量的减少随着相互作用强度的降低,CO 2吸附等温线的形状发生变化。K的亨利定律常数9
Solvent free aldol condensation of propanal to 2-methylpentenal using solid base catalysts
摘要:
Catalytic activities of alkali ion-exchanged zeolites, alumina, alkali treated alumina and hydrotalcite having varied Mg/Al molar ratio were evaluated for aldol condensation of propanal in liquid phase under solvent free conditions. The maximum conversion (97%) of propanal with 99% selectivity of 2-methylpentenal was obtained at 100 degrees C and 10 h using activated hydrotalcite of Mg/Al molar ratio of 3.5 as a catalyst. The basicity of the activated hydrotalcite of Mg/Al ratio 1.5, 2.5 and 3.5 was evaluated by isomerization of beta-isophorone to a-isophorone as a model test reaction reported for basicity measurement. The effect of amount of catalyst and temperature on the conversion of propanal, selectivity of 2-methylpentenal and initial rate of reaction were studied in detail. The activation energy for propanal condensation under solvent free condition was found to be 58 kJ using activated hydrotalcite of Mg/Al molar ratio 3.5 as a catalyst. The catalyst was recycled six times without any significant loss in conversion and selectivity. (c) 2007 Elsevier B.V. All rights reserved.
Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO<sub>2</sub>
作者:Shuai Che、Tao Du、Yan Li Song、Xin Fang、Yi Song Wang
DOI:10.1002/zaac.201900040
日期:2019.6.14
Ammonium type chabazite (NH4CHA) and magnesium type chabazite (MgCHA) was prepared by hydrothermal synthesis and hydrothermal ion exchange. The structure and morphology of ion‐exchangedchabazite was characterized with various experimental techniques such as XRD, SEM, and ICP. The gas adsorption amount of chabazite decreases gradually with increase in temperature or decrease in pressure. The adsorption
通过水热合成和水热离子交换制备了铵型菱沸石(NH 4 CHA)和镁型菱沸石(MgCHA)。通过各种实验技术(例如XRD,SEM和ICP)表征了离子交换菱沸石的结构和形态。菱沸石的气体吸附量随着温度的升高或压力的降低而逐渐降低。在273 K下,NH 4 CHA对CO 2的吸附容量为3.33 mmol · g –1,在极压下,NH 4 CHA的饱和吸附容量为3.88 mmol · g –1。一氧化碳2N 2分子由于其线性分子结构和更大的分子极性而比N 2分子更容易被所有菱沸石样品吸收。NH 4 CHA表现出较大的CO 2 / N 2选择性,随温度降低先升高后降低,并在400 K至450 K之间达到最大值。
Shape-selective oxidation of primary alcohols using perruthenate-containing zeolites
作者:Daniel L. Wu、Andrea P. Wight、Mark E. Davis
DOI:10.1039/b212866g
日期:2003.3.6
Potassium perruthenate (KRuO4), a known, effective oxidant for the conversion of primary and secondary alcohols into carbonyl compounds is impregnated into zeolite X and shown to be a shape-selective oxidant using benzyl alcohol (reacted) and pyrenemethanol (not reacted).
过钌酸钾(KRuO4)是一种已知的有效氧化剂,可将伯醇和仲醇转化为羰基化合物,该氧化剂被浸渍到沸石 X 中,并使用苯甲醇(已反应)和芘甲醇(未反应)证明它是一种具有形状选择性的氧化剂。
Magnetic orientation behavior of L-type zeolite with rare-earth elements under low magnetic field
作者:Tomomi Tabata、Anna Nagai、Motohide Matsuda
DOI:10.1039/d2dt01374f
日期:——
The magneticorientation of L-type zeolite ion-exchanged with various rare-earth elements was observed under a low magneticfield of 0.9 T. The orientation along the applied magneticfield was classified into three types: c-axis orientation for Ce3+, Pr3+, Nd3+, Tb3+, Dy3+ and Ho3+, ab-plane orientation for Er3+, Tm3+ and Yb3+, and random orientation for Eu3+ and Gd3+. The different orientation behavior
在0.9 T的低磁场下,观察到与各种稀土元素离子交换的L型沸石的磁取向。沿外加磁场的取向分为三种类型: Ce 3+的c轴取向, Pr 3+、Nd 3+、Tb 3+、Dy 3+和Ho 3+, Er 3+、Tm 3+和Yb 3+的ab平面取向,以及Eu 3+和Gd 3+的随机取向. 不同的取向行为被认为源于引入到沸石结构中的稀土离子的电子结构。
(27)Al NMR property of potassium-loaded sodalite, which shows antiferromagnetic transition around 70 K. is reported. Monotonic narrow spectrum above 70 K is broadened below 70 K. The broadened spectrum is analyzed with an assumption that the broadening is given by dipolar field from magnetic moment in the cage of sodalite. Two Gaussian functions are used for fitting. Widths of each component proportionally scale each other. The ratio between the Gaussian widths of each component of the narrower and the broader components is 15 +/- 3. (C) 2009 Elsevier Ltd. All rights reserved.
Cation Crowding in Zeolites. Reinvestigation of the Crystal Structure of Dehydrated Potassium-Exchanged Zeolite X
作者:Lin Zhu、Karl Seff
DOI:10.1021/jp000710r
日期:2000.9.1
The structure of a single crystal of fully dehydrated K+-exchanged zeoliteX was determined by X-ray diffraction methods in the cubic space group Fd3m at 21 °C; ao = 25.083(5) A. Ion-exchange of a crystal of Na92Si100Al92O384 was done at 80 °C using flowing aqueous 0.1 M KNO3 with pH = 12; 90(3) K+ ions were found per unit cell. R1 = 0.066 for 352 reflections for which Fo > 4 σ(Fo); wR2 based on F2