沸石分子筛封装纳米金属催化材料的研究进展

综述了近几年国内外沸石分子筛封装纳米金属催化材料的研究进展。重点介绍了在沸石晶体中固定活性金属位置,有效地将纳米粒子的高活性和沸石选择性、稳定性的优点结合,在一系列反应中提高催化性能。在沸石晶体中固定独立的金属位点、金属团簇的合成策略、催化性能和机理研究等。特别是金属纳米粒子被高比表面积沸石分子筛封装后解决了金属纳米粒子的聚集和烧结问题。并介绍了沸石分子筛封装纳米金属催化材料目前的局限性和未来的发展前景。     

沸石封装金属纳米颗粒提高多相反应催化性能研究进展

金属和沸石分子筛是两种广泛应用于氧化还原和酸催化反应的重要催化剂,然而,金属纳米颗粒的团聚和烧结效应通常会导致反应过程中催化性能的损失。而具有均一孔道、结构多样性以及比表面积大等优点的沸石分子筛由于缺乏金属活性位极大地限制了其在催化反应中的活性和应用范围,因此,在沸石内部封装具有催化活性的金属纳米颗粒具有重要意义。综述重点介绍了近年来沸石封装金属纳米颗粒(金属@沸石)催化剂的研究进展,通过使用带有有机基团的稳定剂或晶种法等封装金属或金属氧化物的方法,有效地结合了金属颗粒的高活性以及分子筛载体的高选择性,提高反应活性的同时体现了金属-酸位点的协同催化性、选择性、抗浸出性和抗烧结性等优异性能,这些优势使得此类催化剂具有良好的工业应用前景。     

沸石分子筛催化合成异丙苯工艺研究

介绍了沸石分子筛催化合成异丙苯工艺技术在吉化染料厂原苯酚丙酮车间（现为中国石油吉林石化公司双苯厂）异丙苯单元的工业实验情况。结果表明,采用沸石分子筛催化剂生产异丙苯,与固体磷酸催化剂相比,具有收率高、产品质量好、操作费用低、无腐蚀等优点。沸石分子筛催化剂及其工艺用于吉化股份有限公司染料厂原异丙苯单元的技术改造是完全可行的。     

三维金属纳米花的合成和应用研究现状

三维金属纳米花有一系列优越的理化性能,由于结构特异,在催化、传感上应用广泛,还可以用于制作微观尺度的器件,引起了人们极大的兴趣。从选择性刻蚀、模板引导、种子生长法和动力学控制等方面,介绍了近期在三维金属纳米花合成领域取得的进展,并简述了这种纳米粒子在催化以及电催化方面的应用。     

沸石分子筛材料去除CVOCs的研究进展

综述了沸石分子筛材料作为吸附剂和催化剂去除含氯挥发性有机化合物的最新研究进展,分别对沸石吸附、单纯沸石分子筛催化燃烧、沸石负载贵金属催化燃烧、沸石负载单组分金属氧化物催化燃烧、沸石负载多组分金属氧化物催化燃烧等去除CVOCs进行了概述,并对沸石分子筛材料进一步应用提出了展望.     

金属有机骨架材料在催化中的研究进展

简介了金属有机骨架材料（MOFs）的合成方法,主要介绍了MOFs应用于Lewis酸、碱和手性催化中的研究进展,对MOFs材料在催化领域的应用进行了展望。     

沸石择形催化在精细化工中的应用

本文评述沸石分子筛的择形催化作用及其在精细化学品和中间体合成过程中所涉及的一些重要有机反应,以及利用择形沸石催化剂所开发的一些精细化工过程。     

煤矸石合成纳米4A沸石分子筛的工艺研究

根据所选用煤矸石的成分特点提出了利用煤矸石合成纳米4A沸石分子筛的碱溶提取法,研究了该工艺,并通过试验优化了该工艺的技术参数,即用碳酸钠与煤矸石混合灼烧活化,以4mol／L的NaOH溶液提取硅铝酸钠,晶化温度为90℃,晶化时间为1h,合成并表征了质量性能优良的纳米4A沸石分子筛。     

HZSM—5沸石分子筛催化合成乙酸异戊酯的研究

以ＨＺＳＭ－５沸石分子筛为催化剂,应用常压液固相酯化反应合成了乙酸异戊酯。考察了催化剂用量,醇酸比,反应温度和反应时间对酯产率的影响,结果表明,ＨＺＳＭ－５用量为２克,异戊醇／乙酸为１／２．５（ｍｏｌ比）反应温度为１３０～１４０℃,反应时间为３小时,酯产率８４％。     

Evolving applications of zeolite molecular sieves

Zeolite molecular sieves are essential to many processes in adsorption, catalysis and ion exchange. From the separation of air, to petroleum cracking, to water softening and decontamination, these materials influence our everyday lives. Some researchers have come to believe that all the great discoveries in the field of molecular sieves may be in the past. Nothing could be farther from the truth. From new mechanisms for pore size control, to new nanocomposite materials, to approaching the dream of robust, industrial‐scale sieving membranes, to whole new definitions for molecular sieves, new forms and uses of these materials are rapidly evolving. © 2011 Canadian Society for Chemical Engineering     

Characterization and catalytic performance of mesoporous molecular sieves Al-MCM-41 materials

Mesoporous Al-MCM-41 materials of different Si/Al ratios have been synthesized and characterized by X-ray powder diffraction, ²⁷Al and ²⁹Si MAS NMR, differential thermogravimetric analysis, N₂ adsorption measurements, FT-IR and catalytic cracking of alkanes. The experimental results show that the incorporation of aluminium into the framework of MCM-41 has a great effect on the degree of long-distance order, the surface acidities and the mesoporous structures of the materials. With increase of the aluminium content, the amounts of tetrahedral framework aluminium and the acid sites on the samples increase, but the acid strength decreases. Al-MCM-41 materials exhibit high activity for n-C₁₆ ⁰ cracking and good selectivity for producing low carbon alkylenes, particularly for i-C₄ ⁼.     

离子热法合成分子筛研究进展

离子热法合成分子筛是新型的分子筛合成方法。离子液体独特的特性为合成新型分子筛及研究分子筛合成机理提供了新方法。综述了离子热法在合成分子筛方面取得的进展,包括新型分子筛的合成、合成机理的研究及合成方法等,并展望了离子热法合成分子筛的发展前景。     

多级孔分子筛的合成研究进展

多级孔分子筛由于其高的外比表面积、良好的传热及扩散性能,在重油裂化、异丙苯制备、加氢异构化等催化反应中显示出优良的性能。综述近年来多级孔分子筛的合成进展,着重介绍多级孔分子筛的合成方法、合成机理及性质特点。     

多级孔分子筛材料的研究进展

综述了近年来多级孔分子筛的研究进展,主要分为直接合成法和后处理法。直接合成法包括硬模板法和软模板法,后处理法包括脱铝法、脱硅法以及脱铝脱硅联用法。总结了各种处理方法的优点以及存在的问题,旨在为多级孔分子筛的制备提供更多的理论依据,并对其发展前景进行了展望。     

Fabrication and catalytic performance of meso-ZSM-5 zeolite encapsulated ferric oxide nanoparticles for phenol hydroxylation

An encapsulation-structured Fe₂O₃@meso-ZSM-5 (Fe@MZ5) was fabricated by confining Fe₂O₃ nanoparticles (ca. 4 nm) within the ordered mesopores of hierarchical ZSM-5 zeolite (meso-ZSM-5), with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen, respectively. For comparison, catalysts with Fe₂O₃ (ca. 12 nm) encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures. Catalytic phenol hydroxylation performance of the as-prepared catalysts using H₂O₂ as oxidant was compared. Among the encapsulation-structured catalysts, Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity, which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5 (Fe/Z5). Moreover, the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5. The influence of reaction parameters, reusability, and ·OH scavenging ability of the catalysts were also investigated. Based on the above results, the structure-performance relationship of these new catalysts was preliminarily described.     

Basic catalytic properties of as-synthesized molecular sieves

A series of as-synthesized molecular sieves have been tested and revealed useful as basic catalysts for Knoevenagel condensation under mild conditions. In order to understand the role of the Si/Al ratio, the structure, porosity and template agent, fifteen structures were synthesized and studied in this reaction. Siliceous and large pore molecular sieves showed high conversion levels (97%), while aluminum zeolites, even when containing large amount of organic material, showed distinct activity behavior, which was mainly dependent on the amount of framework silicon. This result, in addition to literature data, indicated that most likely siloxy anions (SiO⁻) are the basic active sites. XPS measurements of these hybrid organic–inorganic catalysts showed that O1s binding energy is influenced by the presence of organic template, leading to the conclusion that they are interacting with framework oxygen, possibly balancing framework anions. Calcined siliceous molecular sieves, which had only silanol groups (SiOH), showed negligible catalytic activity (lower than 2%). As-synthesized siliceous molecular sieves have proven to be useful for basic heterogeneous catalysis, particularly for the synthesis of fine chemicals or for catalytic processes demanding strong basic sites.     

Carbon molecular sieves as model active electrode materials in supercapacitors

Various microporous carbon molecular sieves are studied as active electrode material for supercapacitors in order to clarify the controversy about the accessibility of the electrolyte to the micropores. Cyclic voltammetry experiments were performed in electrolytes with different ion size. The results showed a clear ion sieving effect when the porosity of the carbon was similar to that of the ions of the electrolyte. Impedance spectroscopy was also useful to evidence diffusion restrictions of the ions into the pores. The results obtained in this study clearly demonstrate that in aqueous media very narrow micropores (0.5 nm) are still capable of forming the electrical double layer. Therefore, the majority of microporous carbons, with wider porosity, are perfectly suitable as active electrode materials for supercapacitors when aqueous electrolytes are used.