碱金属离子X型沸石的固相离子交换及其催化性能的研究

本文考察了水合13X沸石与碱金属盐类间的固相离子交换反应,并对交换样品的比表面、孔容和异丙醇分解反应活性进行了测定.结果表明,这种类型的固相离子交换在室温下即可发生.体积较大的Cs~+比K~+难于交换,高温焙烧有利于提高Cs~+的交换度.固相交换样品的比表面、孔容变化和异丙醇分解反应活性都与液相交换样品相同,只是交换度的函数,与交换方法无关.与K~+交换样品相比,Cs~+交换样品中Cs~+离子更多地占据超笼,导致更高的超笼局部碱性和脱氢反应活性.     

水合NaX沸石与碱金属盐类间的固相离子交换

通过XRD和吡啶吸附的IR技术考察了水合13X沸石与碱金属盐类间的固相离子交换反应,结果表明,此类固相离子交换在室温下即可发生。一次交换的程度有限,通过重复交换可提高交换度,体积较大的Cs⁺比K⁺难于交换,高温焙烧有利于提高Cs⁺的交换度。     

气固相法制备含钛丝光沸石

以脱铝丝光沸石为母体,采用气固相法合成了含钛丝光沸石,ＩＲ及ＵＶ－Ｖｉｓ光谱表明,以浓ＨＮＯ３深度脱铝样品,钛进入沸石骨架,且以四配位形式存在,具有较好的环己烯环氧化性能;而以稀ＨＮＯ３处理的样品,进入骨架的量较少,大部分以非骨架钛形式存在,环己烯环氧化性能较差。     

含金属Y型沸石的合成,表征及其催化性能研究

在水热合成体系中制备了系列含金属的Y型沸石(金属=铁、铬、钴),并采用XRD、SEM、ICP、FTIR和UV-vis技术对其进行了表征。FTIR和UV-vis测试结果表明Fe(Ⅲ)、Co(Ⅱ)和Mn(Ⅱ)离子进入沸石骨架,而Cr(Ⅲ)则没有。金属离子对所制备产物晶化及组成有很大的影响。此外,还对含金属的Y型沸石在环己烷氧化反应中的催化性能进行了考察。     

β沸石在丙烯醚化反应中的催化性能

研究了β沸石在不同焙烧温度和加入粘合剂条件下对丙烯与异丙醇合成异丙醚的催化性能。并通过ＸＲＤ、ＸＰＳ、ＮＨ３－ＴＰＤ、ＦＴ－ＩＲ及化学吸附等手段表征了β沸石的物理化学性质。结果表明：焙烧对丙烯醚化反应存在一合适的温度范围；Ａｌ２Ｏ３粘合剂提高了丙烯转化率，降低了异丙醇脱水活性；粘合剂使沸石表面上Ｌ酸中心的比例增加；丙烯醚化反应与Ｌ酸中心存在较好的对应关系，而异丙醇脱水反应与Ｂ酸中心对应；高温焙烧β沸石使骨架铝向表面迁移，粘合剂Ａｌ２Ｏ３能抑制沸石的晶胞收缩。     

类固相法快速合成高钙镁离子交换性能的P型分子筛

以硅铝干凝胶为硅源和铝源,氢氧化钠为碱源,采用类固相法快速合成了P型分子筛,并通过X射线衍射（XRD）、扫描电镜（SEM）等手段对产品进行了表征分析。结果表明,硅铝干凝胶的组成n_SiO2/n_Al2O3=5,晶化时间和晶化温度分别为3 h、140℃,原料的组成n_Na2O/n_SiO2、n_H2O/n_SiO2=18.51时,可制备形貌均一、结晶良好的P型分子筛产品。与传统水热法相比,该方法极大地减少了合成过程的用水量,缩短了晶化时间,提高了产品的钙镁离子交换性能,从整体上优化了P型分子筛的合成工艺。     

NO在铜离子交换型沸石上的分解

ＮＯ在铜离子交换型沸石上的催化分解＊韩一帆汪仁（华东理工大学工业催化研究所，上海２００２３７）关键词一氧化氮，催化分解，铜离子交换型沸石随着工业生产的发展和机动车辆的增加，向大气中排放的含氮氧化物（ＮＯｘ）的量日益增多．如何降低大气中ＮＯｘ的浓度，减...     

两亲性Ti-V-β沸石的制备及其相界面催化反应性能的研究

采用三甲基氯硅烷(TMS)和正十八烷基三氯硅烷(OTS)对Ti-V-β沸石样品进行表面修饰,制备出了两亲性TMS-Ti-V-β和OTS-Ti-V-β沸石,通过XRD,FTIR,UV-Vis,SEM和低温氮气吸附-脱附等手段对样品进行了表征。同改性前样品相比,两亲性Ti-V-β沸石骨架未遭破坏,只是晶貌发生了一些改变。其BET比表面积和BJH孔容均稍有下降(Ti-V-β为428 m²·g^-1和0.54 cm³·g^-1, TMS-Ti-V-β为382 m²·g^-1和0.40 cm³·g^-1, OTS-Ti-V-β为290 m²·g^-1和0.28 cm³·g^-1)。这类两亲性沸石能分布于水、油两相界面处,在不加共溶剂及静置的反应条件下,对环己烯水化的相界面反应表现出优良的催化活性( 环己烯的水合率和环己醇的选择性分别为: Ti-V-β 0.61%和76%、OTS-Ti-V-β 2.01%和90%、TMS-Ti-V-β 7.35%和95%)。可以看出,三甲基氯硅烷改性后的TMS-Ti-V-β沸石在相界面催化反应中,具有比改性前高得多的活性。     

碱金属卤化物与NaA分子筛之间的固态离子交换反应

在低于碱金属卤化物熔点的温度下热处理碱金属卤化物和脱水NaA分子筛干混样品时,一部分分散到分子筛内孔的金属离子能够与脱水分子筛进行程度不同的固态离子交换反应,生成的非挥发性NaCl产物将扩散到分子筛笼外单独结晶或剩余的原卤化物形成溶体.热处理温度愈度,离子交换度愈大;在一定温度下热处理干混样品,存在最大离子交换度.     

固相配位化学反应研究XXXIV. 室温下六氰合铁(II)及(III)酸钾 的固相酸碱反 应

本文研究了室温时K~3Fe(CN)~6,K~4Fe(CN)~6在酸碱条件下发生的固相配位化学反应。结果表明:K~3Fe(CN)~6与NaBH~4固相混合物室温下不反应,但加入固体氢氧化钠后,K~3Fe(CN)~6与NaBH~4的固相氧化还原反应在室温下很容易进行。K~4Fe(CN)~6与K~2S~2O~8的固相氧化还原反应在室温下能顺利进行,但当固体KOH存在时,反应明显受到抑制。K~3Fe(CN)~6与K~2C~2O~4.H~2O室温下无反应,但与H~2C~2O~4.2H~2O在室温时即发生固相取代反应。     

二元及三元离子交换体系的统计热力学

本文用统计热力学方法对二元及三元离子交换体系进行了研究,得到了修正选择系数与交换剂组成关系的理论表达式,并得到二元交换体系的交换剂组分活度系数与组成的关系式,即Kielland公式。     

Physicochemical properties of alkali-metal exchanged type X zeolites

The changes in the physicochemical properties of a series of faujasite type X zeolites cation exchanged with K⁺, Rb⁺ and Cs⁺ have been studied by XRD, IR, thermoanalytical methods and sorption measurements. As a consequence of the enhanced scattering of X-rays by larger alkali metal cations, the percent relative intensity of the XRD peaks of cation exchanged zeolites was found to have decreased considerably. The framework IR spectra also showed analogous changes. The alkali metal exchange was found to enhance the thermal stability of the parent zeolite. The available void volume and specific surface area (obtained by low temperature nitrogen sorption) also decreased with the increase in the degree of exchange and cationic size. Equilibrium sorption capacities (298 K andP/P ₀=0.5) for water,n-hexane, cyclohexane and 1,3,5-trimethylbenzene also exhibited the same trend.NCL communication no. 6056.     

Adsorptive properties of X zeolites modified by transition metal cation exchange

The ionic exchange of the NaX zeolite by Ni²⁺ and Cr³⁺ cations was progressively driven and studied by adsorption of nitrogen and carbon dioxide. For each cation-exchanged X zeolite sample, the development of characteristics such as profile of isotherms, RI criterion, isosteric adsorption heat and microporous volume using both the Dubinin–Radushkevich (DR) equation and the t-plot, was followed through the nitrogen adsorption. Results show that the cationic exchange process, in the case of Cr³⁺ introduced at middle degree, is accompanied by a textural damage for Cr(x)X, in contrast to Ni²⁺-exchanged X zeolites. This degradation occurs without significant presence of mesopores, because the RI criterion values were found to be much lower than 2.2. The CO₂ adsorption isotherms were measured at intervals of 30 K from 273 K and the equilibrium pressures ranged from 0.5 to 600 Torr. The experimental data were correlated by the Toth model. The associated three adjustable parameters were estimated by nonlinear least-squares analysis. The effect of temperature on the model parameters and the Henry’s law slope, K _H , represented by the product of Toth parameters, are discussed.     

Studies on basicity of alkali metal cation exchanged β and X zeolites by pyrrole-IR spectroscopy

The strength of basic sites has been measured by pyrrole-IR on alkali metal cation exchanged β and X zeolites, as well as NaOH loaded Naβ. The influence of cation type and the structure of zeolites on their basicity has been studied. The acidic and basic properties of the samples were investigated by NH₃-TPD and isopropanol reaction. It was shown that the strength of basic sites on samples could be characterized by the shift of v_nh band in the pyrrole-IR spectra. The framework oxygen charges were calculated from the Sanderson electronegativity. The changes in basic properties with various alkali metal cation are consistent with the changes of local oxygen charges of the zeolite framework.     

Selective N-Monoalkylation of aniline derivatives by use of alkali cation exchanged X- and Y-type zeolites

Alkali cation exchanged X- and Y-type zeolites are employed to promote the reactions of aniline derivatives with alkylating agents in organic solvent. The N-alkylation is accelerated by the cooperative function of the acid and base sites on the potassium cation exchanged X- and Y-type zeolites to give the N-monoalkylated product in very high selectivity. Especially the use of the zeolite is found to be effective for N-alkylation of deactivated aromatic amines like nitroaniline. The highly selective N-monoalkylation is attributed to the reaction occurring inside the homogeneous narrow cavities of zeolites.     

铀和铀同位素的离子交换过程研究

在浓缩铀同位索的阳离子交换法中,UC_2~(2+)在离子交换树脂中的传质问题具有特别重要的意义.但迄今未见有详细的报道.本文对阳离子交换树脂—HCl溶液体系中的UO_2~(2+)—H~+正、逆交换,特别对~(235)UO_2~(2+)—~(238)UO_2~(2+)交换动力学及机制作了研究和探讨.     

注入镍离子提高钛阴极催化活性的研究

本文研究了注入镍离子的钛电极在5%NaCl-0.01mol·dm^-^3HCl溶液中H^+的阴极还原反应。采用电化学方法及AES, XPS, TEM等对电极的电化学性质、表面元素分布、化学价态及形貌等进行了分析, 发现该类电极对H^+的还原反应具有比纯Ti高得多的催化活性。