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具有内部介孔结构的多级孔分子筛兼具微孔分子筛和介孔材料的功能, 拥有良好的传质和催化特性. 在过去的几十年内, 介孔分子筛在催化、 吸附和分离领域发展迅速. 近年来, 新型合成方法的开发在很大程度上实现了介孔分子筛孔道结构、 组分及形貌灵活可控的调节. 本综述讨论了近期出现的多种新合成路径, 重点介绍了近期发展起来的二次合成制备低硅/铝介孔分子筛、 超分子自组装合成介孔分子筛及有机小分子原位合成介孔分子筛技术. 对这些合成技术的机理进行了讨论, 以期为介孔分子筛未来的发展提供思路. 文章的最后还讨论了不同的合成策略所面临的一些关键性挑战. 相似文献
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《高等学校化学学报》2021,(1)
具有内部介孔结构的多级孔分子筛兼具微孔分子筛和介孔材料的功能,拥有良好的传质和催化特性.在过去的几十年内,介孔分子筛在催化、吸附和分离领域发展迅速.近年来,新型合成方法的开发在很大程度上实现了介孔分子筛孔道结构、组分及形貌灵活可控的调节.本综述讨论了近期出现的多种新合成路径,重点介绍了近期发展起来的二次合成制备低硅/铝介孔分子筛、超分子自组装合成介孔分子筛及有机小分子原位合成介孔分子筛技术.对这些合成技术的机理进行了讨论,以期为介孔分子筛未来的发展提供思路.文章的最后还讨论了不同的合成策略所面临的一些关键性挑战. 相似文献
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介孔分子筛的酸性和水热稳定性 总被引:27,自引:0,他引:27
介孔分子筛材料在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有潜在的应用价值.但是,由于介孔分子筛材料较低的水热稳定性和较弱的酸性,极大地影响了其在催化研究中的广泛应用.本文系统地综述了最近几年在提高介孔分子筛酸性和水热稳定性的研究工作.其中包括:(1)将超酸组份负载于介孔分子筛的孔道中以达到提高介孔分子筛材料的酸强度的目的;(2)通过在合成介孔分子筛的过程中加入无机盐和有机胺等助剂或采用合适的后处理方法以提高介孔分子筛的水热稳定性;(3)通过新型模板剂来合成具有较高水热稳定性的介孔分子筛材料;(4)利用具有沸石分子筛基本结构单元的沸石分子筛导向剂与表面活性剂自组装来合成具有强酸中心和高温水热稳定的介孔分子筛材料. 相似文献
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催化新材料——钛硅分子筛合成及应用研究* 总被引:10,自引:0,他引:10
评述了钛硅分子筛新催化材料的合成及其催化应用的研究进展, 包括钛硅分子筛(TS21) 的水热合成方法、原料、模板剂、影响因素、TS21 同晶取代法合成、表征、活性中心、钛硅分子筛双氧水体系的应用研究及近年中孔钛硅分子筛的进展。对未来的研究提出了建议。 相似文献
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由沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的新型介孔分子筛材料 总被引:18,自引:0,他引:18
人们合成了一系列介孔分子筛材料,并发现它们在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有很大的潜在应用价值.但是,介孔分子筛材料相对于微孔沸石分子筛存在着两个致命弱点:较低的水热稳定性和较不活泼的催化活性中心.这两个弱点大大地影响了介孔分子筛在催化反应中的广泛应用.本文系统地综述了最近几年利用沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的介孔分子筛材料的研究进展.这包括利用硅铝沸石纳米粒子自组装制备具有强酸性和水热稳定的新型介孔硅铝分子筛材料,利用钛硅沸石纳米粒子自组装制备具有高催化氧化活性中心和水热稳定的新型钛硅介孔分子筛材料,以及利用含有不同杂原子的沸石纳米粒子自组装制备一系列水热稳定的新型介孔分子筛催化材料. 相似文献
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Methods for palladium-catalyzed aerobic oxidation of alcohols often benefit from the presence of molecular sieves. This report explores the effect of molecular sieves on the Pd(OAc)2/pyridine and Pd(OAc)2/DMSO (DMSO = dimethyl sulfoxide) catalyst systems by performing kinetic studies of alcohol oxidation in the presence and absence of molecular sieves. Molecular sieves enhance the rate of the Pd(OAc)2/pyridine-catalyzed oxidation of alcohols, and the effect is attributed to the ability of molecular sieves to serve as a Br?nsted base. In contrast, no rate enhancement is observed for the Pd(OAc)2/DMSO-catalyzed reaction. Both catalyst systems exhibit improved catalyst stability in the presence of molecular sieves, manifested by higher catalytic turnover numbers. Control experiments indicate that neither of these beneficial effects is associated with the ability of molecular sieves to absorb water, a stoichiometric byproduct of these reactions. Finally, the use of simultaneous gas-uptake and in-situ IR spectroscopic studies reveal that molecular sieves inhibit the disproportionation of H2O2, an observation that contradicts a previous suggestion that the beneficial effect of molecular sieves may arise from their ability to promote H2O2 disproportionation. 相似文献
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制备了介孔MCM-41分子筛和三种杂原子(Zn、Ba和Ce)介孔MCM-41分子筛,通过X射线衍射(XRD)、红外光谱(FT-IR)、低温N_2吸附-脱附等手段对其进行表征,研究了几种介孔分子筛对氮含量为1732μg/g含喹啉模拟柴油的吸附脱氮性能。结果表明,所制备的几种分子筛均具有典型的介孔结构,且杂原子已进入到分子筛骨架中。利用Materials Studio软件构建介孔分子筛模型,模拟的XRD谱图与实验结果基本相符;进一步模拟了喹啉分子在杂原子介孔分子筛团簇上的吸附,计算了吸附能及被吸附分子和吸附中心的距离(d_((N-M)))。几种分子筛的吸附脱氮性能顺序依次为Zn-MCM-41 Ce-MCM-41 Ba-MCM-41 MCM-41;Zn-MCM-41的吸附性能最好,吸附能最大,吸附分子和吸附中心的距离d_((N-M))最小。吸附时间对杂原子介孔分子筛的吸附脱氮性能具有较大影响,而吸附温度的影响相对较小;Zn-MCM-41、Ba-MCM-41和Ce-MCM-41分子筛的最佳吸附时间分别为40、10和30 min,最佳吸附温度分别为40、30和40℃。 相似文献
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MnAPO-11 molecular sieves with medium size elliptical pore are synthesized and characterized. Transition state shape-selective catalysis of these molecular sieves are studied. Methylation of alkylaromatic compounds were efficiently catalyzed by these molecular sieves while aromatic ethylation was almost negligible. The size of the alkylating agents was the key factor for the transition state dimension in the aromatic alkylation, not the size of aromatic compounds. The mole fraction of o-isomer for methylation of alkylaromatic compounds was dependent on the size of the alkyl groups. 相似文献
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在固定床吸附器上模拟无粘结剂5A分子筛的失活过程,并对失活分子筛进行氧化再生研究。结果表明,焦炭会堵塞部分分子筛孔道,导致失活分子筛的比表面积和孔容减小、平均孔径增加。焦炭含量增加,分子筛的失活度增加,但增加的速率逐渐减小。氧化反应温度由582K升至787K,焦炭脱除率由64%增至100%。失活分子筛于787K下氧化处理后,其上焦炭被完全脱除,分子筛的吸附活性完全恢复。氧化再生后分子筛的比表面积和孔容增加,但难以恢复至新鲜分子筛的水平。在685K~884K,实验得到的无粘结剂5A分子筛上焦炭的氧化脱除宏观动力学方程为:ln(C0/C) = 0.013exp(-28122.1/T) (pO2)0.32t。 相似文献
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The nanometer and micrometer molecular sieves MCM-41 were prepared by a hydrothermal method. Cadmium (II) was exchanged into the molecular sieves by ion-exchange, and thioacetamide was then used as a precursor of hydrogen sulfide for sulphidizing the (MCM-41)-cadmium samples to prepare the host-guest composite materials (MCM-41)-CdS. By means of chemical analysis, powder X-ray diffraction, infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid state diffuse reflectance absorption spectroscopy and luminescence, the prepared materials were characterized. The chemical analysis shows that the guest is successfully trapped in the molecular sieves. The powder X-ray diffraction suggests that the frameworks of the molecular sieves in the prepared host-guest composite materials are retained during the preparative process. They are intact and the degrees of crystallinity are still very high. The infrared spectra show that the frameworks of the prepared host-guest materials keep intact. The low temperature nitrogen adsorption-desorption studies indicate that the pore volumes, the pore sizes and the surface areas of the prepared composite materials decrease relative to those of the MCM-41 molecular sieve hosts. This shows that the guests are successfully encapsulated in the channels of the molecular sieves. The solid state diffuse reflectance absorption spectra of the prepared host-guest composites show some blue-shifts relative to that of bulk cadmium sulfide, indicating that the guests are trapped in the channels of the molecular sieves. This shows the obvious stereoscopic confinement effect of the molecular sieve host on the nanometer cadmium sulfide guest. The (nanometer MCM-41)-CdS and (micrometer MCM-41)-CdS samples show obvious luminescence. 相似文献
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Atienzar P Díaz-Cabañas MJ Moliner M Peris E Corma A García H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(31):8733-8738
We have developed a novel concept that uses monomers required for making conducting polymers as organic structure-directing agents, for the synthesis of microporous molecular sieves. We show that these monomers facilitate the formation of crystalline and amorphous molecular sieves depending on the synthesis procedure. The monomers filling the pores of the silicates can be polymerized under certain conditions, resulting in a polymer immobilized and protected inside the matrix. The concept was exemplified with para-phenylenemethylene-bis(1-tetrahydrothiophenium) and para-phenylenemethylene-bis(trimethylammonium) that were used to template microporous molecular sieves and subsequently to obtain poly-para-phenylenevinylene (PPV) inside the matrix. The organic self-assembled organic-inorganic material was extensively characterized and the implication on electrical conductivity is presented. 相似文献
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在酸性溶液中利用溶胶凝胶-pH值控制两步法直接合成FexOy/SBA-15介孔分子筛,同时利用场发射扫描电子显微镜(FESEM)、小角度X射线衍射(Low-angle XRD)、透射电子显微镜(TEM)以及振动样品磁强计(VSM)对制备的各种SBA-15介孔分子筛进行结构以及性能的测试、表征。结果显示FexOy均匀地分散在SBA-15的骨架中,而且会对SBA-15介孔分子筛起钉轧作用。而后着重研究了FexOy的加入对SBA-15介孔分子筛的热稳定性、催化特性以及磁学性能的影响。FexOy的引入可以增加制备的SBA-15介孔分子筛的热稳定性;FexOy的引入可以改善SBA-15介孔分子筛的催化活性,得到了开口的、石墨化程度较好的纳米碳管。FexOy的引入使SBA-15介孔分子筛具有明显的铁磁性。 相似文献
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Dr. Na Sheng Ye Ma Qianwen Zhu Xin Hong Juan Zhang Prof. Jun Xu Feng Deng Prof. Junliang Sun Prof. Zhaochi Feng Prof. Liang Wang Prof. Xiangju Meng Prof. Feng-Shou Xiao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11408-11411
Unlike conventional aluminosilicate zeolites synthesized in alkaline media, aluminophosphate molecular sieves (AlPOs) have always been prepared under acidic conditions in the past three decades; this has been regarded as one of essential factors for synthesis, except for the case of silica-substituted analogues (SAPOs). For the first time, we demonstrate herein a simple and generalized route for synthesizing various types of aluminophosphate molecular sieves in alkaline media. A series of aluminophosphate sieves and their analogues have been prepared with different quaternary ammonium cations as structure-directing agents in this manner. The above successes have extended the systematic media from acidic or neutral to alkaline for the preparation of a series of aluminophosphate molecular sieves, which possibly open an alternative route for the synthesis of aluminophosphate molecular sieves. 相似文献