Bisphenol F Synthesis Over Mesoporous Aluminosilicate MCM-41 Molecular Sieves

Temperature-programmed desorption, X-ray photoelectron spectroscopy (XPS) spectroscopy and catalytic test reaction have been applied to investigate acid sites in a microporous activated carbon (Norit RX 1 Extra). Treatment with HNO₃ generates acid sites in the pristine carbon. XPS data show an increase of the amount of carboxyl and hydroxyl groups on the activated carbon surface. The thermodesorption profiles of the material corroborate the XPS data and indicate the presence of hydroxyl groups of carboxylic acids. The results obtained by these methods indicate the presence of acid sites. Thus, the acidity of the carbon was tested in the esterification of organic acids with alcohols. The pristine carbon presents no activity. By contrast, the treated carbon presents enough acidity to carry out the reaction achieving conversion values of around 45% for the reaction of benzoic acid with ethanol in a batch reactor. Such a value increases if the reaction is carried out under ultrasound activation, affording conversion values of around 85%. The selectivity of the reactions is high, around 95%. Only in the case of 1-octanol are some side-products observed, due to the oxidation of the alcohol.     

沸石分子筛基功能光学材料的研究进展

沸石分子筛的孔道与笼尺寸属于纳米团蔟范围,以其为主体,将具有特定功能的其他分子作为客体装入孔道或笼内,生成微观有序的纳米团蔟,所得到的复合材料称为分子筛基材料。分子筛的孔道内生成的纳米蔟在微观上是有高度有序的,这对于功能材料的性质是非常重要的。本文综述了这一类材料如纳米激光器和非线性光学材料的研究进展;同时也概述了两种新兴的科学与技术－分形理论和组合化学在分子筛基材料中的应用前景。     

Synthesis, Characterization and Catalytic Properties of Vanadium Substituted Hexagonal Mesoporous Aluminophosphate Molecular Sieves

Vanadium substituted hexagonal mesoporous aluminophosphate (VHMA) molecular sieves were synthesized hydrothermally. Various physicochemical studies, viz., XRD, TEM, DRUV–VIS, EPR, N₂ sorption were used to find the location of vanadium ions in the VHMA matrix and to check the mesoporosity of the sample. The catalytic activity of VHMA was evaluated, under mild reaction conditions, for the oxidation of cyclohexane reaction, which mainly gave cyclohexanol and cyclohexanone along with a very small amount of a secondary product, viz., cyclohexyl acetate. A comparative study, with other vanadium containing molecular sieves, viz., VMCM-41, VAPO-5 and VS-1, on the application of VHMA catalyst reveal that the latter exhibits excellent activity, selectivity and stability to leaching for the oxidation reaction of cycloalkanes, including bulkier molecules such as cyclododecane.     

Recent Advances in Catalysis Over Mesoporous Molecular Sieves

This overview covers the recent achievements in the application of mesoporous molecular sieves as catalysts and catalyst supports. Main structural and textural features are outlined in relation to the novel synthesis approaches of mesoporous molecular sieves and understanding of their properties. For application of mesoporous molecular sieves as catalysts different ways of introduction of active sites on their surfaces are provided. The main part describes selected catalytic reactions catalyzed by mesoporous molecular sieves focused on very recent papers. The examples include metathesis, acylation reactions, C–C coupling reactions of Heck and Suzuki types, base-catalyzed reactions (Knoevenagel and Michael additions, Claisen-Schmidt condensation, Tischenko reaction) and last but not least immobilization of organometallic complexes for different catalytic applications including chiral catalysts.     

粉煤灰和煤矸石合成沸石分子筛的研究进展

简述了粉煤灰和煤矸石的组成、分类、性质和制取分子筛的方法。指出了应加强煤矸石分类的研究,从而指导煤矸石的利用。生产分子筛是粉煤灰和煤矸石的高附加值化工利用的有效途径之一,粉煤灰水热合成分子筛研究较多,但是反应时间太长,微波辅助合成分子筛可以加快粉煤灰中的硅和铝溶解,从而降低活化时间,但需要解决微波合成分子筛的工程放大问题。     

磷酸铝介孔分子筛的合成

选用了不同类型的表面活性剂作为模板剂合成磷酸铝介孔分子筛,实验结果表明,脂肪胺模板剂的浓度不会影响分子筛介孔相构型,介孔分子筛的孔径随烷基胺的链长增加而增大,其比表面积均达到了200 m2/g以上.类型相同的表面活性剂作模板剂时,分子筛的孔径和比表面积并不随其浓度增加而增加.所合成的磷酸铝分子筛TG和DTA曲线表明,磷酸铝分子筛在850 ℃以前具有一定的热稳定性.     

分子筛负载TiO_2光催化材料制备研究进展

简要介绍了分子筛的基本构成和结构,TiO_2光催化原理,分子筛负载TiO_2光催化机理,分子筛的合成方法,分子筛负载TiO_2的合成方法及其应用,并指出这类材料存在的问题及应用前景。     

Vapor-Phase Tertiary Butylation of Phenol Over Mesoporous Gallosilicate Molecular Sieves

Isomorphously substituted GaMCM-41 molecular sieves with different Si:Ga ratio were synthesized and characterized systematically by various analytical and spectroscopic techniques. Temperature-programmed desorption of ammonia was used to identify the nature of acidic sites. For the first time, the vapor-phase tertiary butylation of phenol reaction was carried out over protonated GaMCM-41. The catalysts showed higher (phenol) conversion and good (para-tertiary butyl phenol) selectivity over the Al- and Fe-analogs of MCM-41. Further, the gallosilicates showed good stability both before and after the reaction compared to the aluminosilicates or ferrisilicates.     

Separation of Trimethylbenzene Isomers on Molecular Sieves 13X in High Pressure Carbon Dioxide

Abstract

An experimental study of the separation of 1,2,4-and 1,3,5-trimethylbenzenes from a mixture containing the weight composition 56% 1,2,4-trimethylbenzene and 44% 1,3,5-trimethylbenzene on molecular sieves 13X in high pressure carbon dioxide was performed. For a pulse of 1.18 cm³ of trimethylbenzene isomers and 40 g of molecular sieves 13X, the effects of pressure, temperature, and flow rate on separation effectiveness were examined. The results indicated that the most appropriate operating conditions for obtaining a higher recovery of each isomer with a purity of at least 98% and a shorter mean retention time for 1,3,5-trimethylbenzene were a temperature of around 363 K, a pressure of 74.8 atm, and a flow rate of 15.0 cm³/min.     

模板剂在分子筛合成中的作用

本文着重介绍了模板剂在分子筛合成中的应用,对采用模板剂合成的ZSM和SAPO系列分子筛的结构及模板剂对合成分子筛的影响作了重点介绍,并对国内外分子筛合成中常用的模板剂作了较为系统地介绍.     

微波促进双介孔分子筛的合成

在微波辐射下采用一种模板剂P123(EO20PO70EO20)合成出双介孔分子筛。微波辐射功率及辐射时间分别为140 W和0.5 h。XRD,BET,SEM及TEM表征技术证实了样品具有两种介孔孔道分布的结构特征。研究表明适量的模板剂及微波辐射对双介孔骨架结构的形成起着决定性的作用。     

VAPO-11分子筛的合成与表征

用水热合成法合成了钒取代磷铝酸盐分子筛VAPO-11.并对所合成分子筛用X射线衍射(XRD)、电子扫描电镜(SEM)、热分析(TG-DTA)和BET比表面积法进行表征.考察了晶化温度和钒铝比等对VAPO-11合成的影响.合成出的分子筛为柱状晶片的团状聚集体.     

中孔沸石分子筛合成研究进展

对当前国际国内中孔分子筛的合成研究状况进行了综述 ,重点介绍了分子筛合成的新方法、模板剂的作用、合成机理、影响合成的因素、元素掺杂等合成中的关键问题 ,并展望了分子筛合成的发展趋势。     

纳米介孔分子筛的合成及催化应用研究进展

具有纳米级颗粒尺寸的介孔分子筛因其双纳米性质,不仅具有传统介孔分子筛大比表面积、规整孔道结构的特点,而且具有性能优良的纳米级颗粒尺寸,在大分子有机物的催化反应中具有更好的应用潜力。主要介绍了纳米介孔分子筛的合成进展及其在催化领域的应用概况,同时也对未来的发展状况和应用前景作了预测和展望。     

硼改性沸石上甲基叔丁基醚气相合成反应

考察了HZSM-5、HY和Hβ等沸石催化剂上气相合成甲基叔丁基醚(MTBE)的反应性能,发现Hβ沸石对MTBE的合成具有比其它沸石更高的活性和选择性.研究了加入粘合剂后催化剂活性和选择性的变化.通过对催化剂的酸性表征,认为L酸中心对MTBE合成具有重要作用.在此基础上,设计制备出了硼改性B2O3/Hβ-Al2O3催化剂,使MTBE产率明显提高,选择性接近100%.讨论了反应性能与催化剂表面酸性的关系.     

复合分子筛的合成及其应用进展

微孔-介孔复合分子筛由于兼有微孔分子筛和介孔分子筛的优点,而且可在一定程度上弥补各自的缺点,已成为近年来倍受关注的催化新材料之一。文章综述了近年来微孔-介孔复合分子筛的合成方法和催化应用研究进展,重点介绍了单模板剂法、双模板剂法、微孔沸石硅源法、孔壁晶化法、附晶生长法等方法及其催化应用情况,并对微孔-介孔复合分子筛的应用前景进行了展望。     

Synthesis of Polycarbonate Precursors over Titanosilicate Molecular Sieves

A novel catalytic application of titanosilicate molecular sieves (TS-1 and TiMCM-41), in the synthesis of polycarbonate precursors like cyclic carbonates and dimethyl and diphenyl carbonates, avoiding toxic chemicals like phosgene or CO, is reported. Cyclic carbonates were prepared, over TS-1 and TiMCM-41, in high yields, by cycloaddition of CO₂ to epoxides, like epichlorohydrin, propylene oxide and styrene oxide, at low temperatures and pressures. Further, transesterification of the cyclic carbonates with methanol and phenol, over TiMCM-41, yielded other polycarbonate precursors like dimethyl carbonate (DMC) and diphenyl carbonate (DPC). The cyclic carbonates could also be synthesized from the olefins in the same reactor by reacting the olefins, in the presence of TiMCM-41, with a mixture of an epoxidizing agent (like H₂O₂ or tert-butyl hydroperoxide) and CO₂.     

沸石负载纳米TiO2光催化剂水处理研究进展

近年来,利用沸石和纳米TiO2的协同效应制备出沸石负载纳米TiO2高效复合光催化剂的研究引起了人们的特别关注。本文结合国内外沸石的发展状况,对沸石的组成、结构、性能及改性方式作了简要的阐述,对沸石负载纳米TiO2光催化剂的光催化机理、负载方式及国内外水污染处理研究现状作了较为详细的总结。