Stability and characterization of mesoporous molecular sieve using natural clay as a raw material obtained by microwave irradiation

Mesoporous molecular sieve was synthesized via microwave irradiation method, and using natural clay, sodium silicate and aluminum chloride as raw materials and cetyl trimethyl ammonium bromide (CTAB) as a template agent under alkaline condition. The samples were characterized by various analytic and spectroscopic tools such as XRD, FT-IR, TEM, TG-DSC and N₂ physical adsorption, respectively. The results show that the synthesized sample has typical mesoporous structure and exhibits good mesoporous ordering. On the other hand, the as synthesized sample after calcination at 550 °C for 10 h has a surface area of 576.0 m²/g and an average pore size of 4.83 nm. Furthermore, the synthesized mesoporous molecular sieve still exhibits good mesoporous ordering after calcination at 750 °C for 3 h or hydrothermal treatment at 100 °C for 10 days.     

Facile synthesis and characterization of acid-base bifunctionalized mesoporous silica

A simple acid-base bifunctionalized approach has been developed through grinding the precursors, magnesium and aluminium nitrates, with the as-prepared SBA-15, and then the generation of acid-base active sites and removal of host template were combined into a single step in the subsequent calcination procedure. A series of acid-base bifunctional mesoporous materials MgO-Al₂O₃-SBA-15 (MA-SBA-15) have been successfully synthesized by means of this approach. X-ray diffraction (XRD), high-resolution transmission electron microscopes (HRTEMs), N₂ adsorption, FT-IR spectra, ²⁷Al and ²⁹Si magic-angle-spinning (MAS) NMR, NH₃- and CO₂-temperature programmed desorption (TPD), pyridine adsorption were employed to characterize the resultant mesoporous materials. The results indicate that the guests can be well dispersed in the channel of SBA-15, and the resultant materials exhibit excellent acid-basic properties with well mesoporous backbone, which make it possessing high activity for the synthesis of ethyl methyl carbonate, an important asymmetric carbonate ester compound.     

过渡金属(Ti,Zr,Mn,Cu,Mo,Cr,Co)离子掺杂的MCM-48的合成、表征与催化性能研究

合成了掺杂Ti、Zr、Mn、Cu、Mo、Cr、和Co过渡金属离子的中介孔分子筛MCM-48.通过TEM、孔分布测试、XRD、电子能谱、红外吸收及热失重分析对掺杂的MCM-48进行结构表征,并研究了其催化性能.结果表明,掺杂Ti、Cr、Zr的MCM-48具有优良的催化性能.     

中孔分子筛MCM-41的合成与表征

以白炭黑和正硅酸乙酯为硅源,十二、十六烷基三甲基铵为模板剂,用水热法和室温直接法合成出中孔分子筛MCM-41,考察了对合成的影响因素,用红外光谱、吸附、孔分布、热分析等手段对这两种产物进行了表征。结果表明:这种分子筛可以在很宽的配比范围内获得,但较高水硅比更有利于合成;在水硅比较低的体系中得到了一种类MCM-41中孔相(亦应属于MCM-41),其XRD衍射峰较宽,2θ角度偏低,具有类似于无定形硅铝酸盐的骨架结构。     

New Routes to the Synthesis of Mesoporous Materials and Their Properties

The factors that influence the hydrothermal synthesis of MCM-41 were investigated, and it was found that compared with those from high H₂O/SiO₂ systems(designated MCM-41-A), the products from low H₂O/SiO₂ systems(designated MCM-41-B) exhibited a less-defined X-ray powder diffraction (XRD) pattern with a broader main reflection peak at a lower 2θ diffraction angle. MCM-41-B possesses a smaller surface area but a larger pore size than MCM-41-A. New routes including direct thermal treatment, room-temperature crystallization and microwave heating were developed for the formation of MCM-41, and the properties of the products prepared from these new routes were compared with those of the MCM-41 hydrothermally synthesized. The pore sizes of MCM-41 materials are uniformly distributed with an effective pore diameter that falls into the range of 2-4 nm, where as the products from wet-gel thermal treatment possess two kinds of mesopores:the well-defined smaller pores distributed at 3 nm and the larger one within 8-20 nm. The MAS NMR spectroscopy revealed that after calcination to remove the organic template in Al-containing MCM-41, a small part of the tetrahedrally-coordinated framework aluminum atoms became octahedrally-coordinated and a considerable amount of Si-OH species were generated.     

模板剂对全硅MCM-41介孔分子筛结构的影响

分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性（NaOH）介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容（分别为4.72 nm和1.14 cm3•g-1）的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂.     

氨丙基官能化HMS介孔分子筛的合成及表征

沿S0I0路径,以十六胺为模板剂,以3-氨丙基三乙氧基硅烷为有机硅源,通过与TEOS共水解沉淀合成了氨丙基官能化HMS介孔分子筛.采用粉末X-射线衍射分析、N2吸/脱附、扫描电镜分析、高分辨透射电镜分析、傅立叶变换红外分析以及元素分析等表征手段,对所合成的材料进行表征.氨丙基官能化HMS介孔分子筛具有worm-like孔道结构,且较为均一的孔径分布.研究了前体硅源中3-氨丙基三乙氧基硅烷含量的变化对氨丙基官能化HMS介孔分子筛的相结构及织构性能的影响.傅立叶变换红外分析表明,NH2-CH2-CH2-CH2有机基团分布在杂化HMS介孔孔道中.     

Sustainable and efficient 2,3-dihydroquinazolin-4(1H)-ones production over heterogeneous and recyclable Al-MCM-41 supported dual imidazolium ionic liquids nanocomposites

A type of Al-MCM-41 supported dual imidazolium ionic liquids nanocomposites have been synthesized and efficiently used as catalysts in the one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-ones. It was shown that the highest efficiency was achieved in the condensation of a range of aldehydes and anthranilamide in the presence of the (2)Al-MCM-41@ILCeCl₄(0.5) solid catalyst under mild conditions. Hot filtration test confirmed that the reaction follows a heterogeneous pathway. Moreover, the catalyst was stable, very active, robust, and displayed good recyclability without significant loss of catalytic activity after five consecutive cycles during the process. Green reaction conditions, operational simplicity, feasibility, high to excellent yields, sustainability of the functionalized catalyst are the main highlights of the present protocol.     

Stiffness-Transformable Nanoplatforms Responsive to the Tumor Microenvironment for Enhanced Tumor Therapeutic Efficacy

Herein, we report, for the first time, a unique stiffness-transformable manganese oxide hybridized mesoporous organosilica nanoplatform (MMON) for enhancing tumor therapeutic efficacy. The prepared MMONs had a quasi-spherical morphology and were completely transformed into soft bowl-like nanocapsules in the simulated tumor microenvironment through the breakage of Mn−O bonds, which decreased their Young's modulus from 165.7 to 84.5 MPa. Due to their unique stiffness transformation properties, the MMONs had reduced macrophage internalization, improved tumor cell uptake, and enhanced penetration of multicellular spheroids. In addition, in vivo experiments showed that the MMONs displayed a 3.79- and 2.90-fold decrease in non-specific liver distribution and a 2.87- and 1.83-fold increase in tumor accumulation compared to their soft and stiff counterparts, respectively. Furthermore, chlorin e6 (Ce6) modified MMONs had significantly improved photodynamic therapeutic effect.