介孔氧化铝负载Ni-Co氧化物催化剂上丙烷氧化脱氢制丙烯

以非离子型三嵌段共聚物作为模板剂, 异丙醇铝为氧化铝的前驱物, 采用一锅法合成了一系列介孔氧化铝负载镍氧化物、钴氧化物以及镍-钴双金属氧化物催化剂, 并以介孔氧化铝为载体, 采用浸渍法制备了负载Ni-Co 氧化物催化剂. 采用N₂吸附-脱附、高分辨透射电镜(HRTEM)、X射线粉末衍射(XRD)、H₂程序升温还原(H₂-TPR)以及激光拉曼光谱(LRS)等技术对催化剂的结构与性质进行表征, 并考察了催化剂的丙烷氧化脱氢反应性能. 结果表明: 一锅法制备的各催化剂均有大的比表面积和规整的孔道结构, 且负载的金属氧化物高度分散; 而浸渍法制备的催化剂, 其载体的介孔结构被破坏并有Co₃O₄晶相生成. 在考察的催化剂中, 一锅法合成的介孔氧化铝负载Ni-Co 氧化物催化剂表现出最佳的丙烷氧化脱氢性能. 在450 °C、C₃H₈:O₂:N₂的摩尔比为1:1:4和空速(GHSV)为10000 mL·g^-1·h^-1条件下, 该催化剂上丙烯产率为10.3%, 远高于浸渍法制备的催化剂上所获得的丙烯产率(2.4%). 关联催化剂表征和反应结果, 讨论了催化剂结构与性能之间的关系.     

三维有序大孔-介孔二氧化硅的可控制备及表征

以聚甲基丙烯酸甲酯(PMMA)胶晶为大孔模板、嵌段共聚物P123为介孔模板,利用双模板剂法进行了三维有序大孔-介孔二氧化硅材料的制备研究。采用SEM、TEM、低角XRD以及N₂吸脱附技术对样品进行了表征。结果表明,通过简单的调控PMMA胶晶模板的组装过程,就可以调变合成材料中的大孔结构,从而轻松地实现可控的制备出具有网状或者层状结构的三维有序大孔-介孔二氧化硅材料,并提出了其可能的形成机理。此外,所制备的三维有序大孔-介孔二氧化硅样品均具有较大的BET比表面积(>550m₂·g^-1),大孔孔径200nm左右,介孔孔径分布集中于3.5nm左右。     

介孔氧化钨电色薄膜的制备与性能研究

采用一种新的非离子型gemini表面活性剂结构导向模板, 成功制备了介孔氧化钨薄膜. 通过SAXRD, TEM和N₂吸附-脱附等方法考察薄膜的制备和微结构特性, 发现获得的产物具有三维蠕虫介孔结构, 比表面积可达145.5 m²• g^－1. 测定了该薄膜在无水高氯酸锂/碳酸丙烯酯电解质溶液中的循环伏安和电致变色性能, 并与无模板薄膜进行了对比研究. 研究表明, 由于具有更大的电化学活性比表面, 纳米介孔氧化钨薄膜表现出增强的电色性能, 在633 nm波长处的透过率调制幅度可达60%以上, 着色效率为51.7 cm²•C^－1.     

介孔α-Fe2O3表面配合反应平衡常数测定

采用十二胺为模板剂、氨水做沉淀剂成功制备了介孔α-Fe₂O₃, 通过粉末X射线衍射(XRD)、透射电镜(TEM)、N₂吸附/脱附技术对样品晶相、形貌和比表面积进行了表征. 根据介孔α-Fe₂O₃悬浮液的酸碱滴定数据, 使用FITEQL软件, 采用双电层恒电容模型计算得出了介孔α-Fe₂O₃的表面酸碱反应平衡常数. 在此基础上研究了Cu^2＋, Pb^2＋, Zn^2＋在介孔氧化铁表面的吸附行为, 使用WinSGW软件模拟得出了相应的表面配合反应平衡常数并讨论了其吸附机理.     

有序介孔碳负载Fe、Co、Ni纳米晶的软模板合成及其表征

报道了在有序介孔碳基体中一步合成负载Fe、Co、Ni纳米晶的方法. 以间二苯酚和甲醛为碳源, F127为模板剂, Fe、Co、Ni的硝酸盐为前驱体, 通过软模板组装路线在酸性条件下合成了负载型有序介孔碳复合材料. 采用X射线衍射(XRD)、透射电镜(TEM)和氮气吸附等手段对所合成材料进行了表征. 结果表明: 合成的材料具有类似于SBA-15的有序介孔结构, 有序介孔碳负载Fe、Co、Ni纳米晶复合材料的比表面积分别为586、626和698 m²·g^-1. XRD和TEM表征结果证实了金属物种以高分散纳米晶的形式分布在介孔碳基体中.     

高比表面CexZr1-xO2复合氧化物的制备及表征

分别采用共沉淀法和阴离子表面活性剂模板法制备了Ce_xZr_1-xO₂复合氧化物。采用XRD、AFM、FTIR以及N₂吸附-脱附等方法对样品进行了表征。结果表明，共沉淀法合成的样品在500 ℃煅烧2 h后，生成了立方相Ce_0.75Zr_0.25O₂和四方相Ce_0.5Zr_0.5O₂固溶体，比表面积为62.1 m²·g^-1，孔体积为0.097 cm³·g^-1；以阴离子表面活性剂十二烷基苯磺酸钠(SDBS)为模板剂，乙二胺为助模板剂合成的样品在500 ℃煅烧2 h后，生成了纯四方相Ce_0.5Zr_0.5O₂固溶体，比表面积为180 m²·g^-1，孔体积为0.182 cm³·g^-1。结果表明，以阴离子表面活性剂SDBS为模板剂，可以合成高比表面积且具有介孔结构的Ce_0.5Zr_0.5O₂复合氧化物；加入乙二胺作为助模板剂可明显的提高比表面积和孔体积。     

疏水介孔二氧化硅膜的制备与表征

用甲基三乙氧基硅烷(MTES)代替部分正硅酸乙酯(TEOS)作为前驱体，以聚乙烯醚-聚丙烯醚-聚乙烯醚三嵌段共聚物(P123)作有机模板剂，通过共水解缩聚反应制备了甲基修饰的介孔SiO₂膜。利用N₂吸附、FTIR、²⁹Si MAS NMR以及接触角测量仪对膜的孔结构和疏水性进行了表征。结果表明，修饰后的膜材料具有良好的介孔结构，最可几孔径为4.65 nm，孔体积为0.69 cm³·g^-1，比表面积为938.4 m²·g^-1；同时疏水性明显提高，当n_MTES/n_TEOS达到1.0时，其对水的接触角达到109°± 1.1°。气体渗透实验表明气体通过膜孔的扩散由努森机制所控制。     

微孔/介孔复合分子筛的合成及其对CO2的吸附性能

采用两步晶化法将合成的沸石前驱液(S)或沸石固体粉末(P)经不同浓度(c)的NaOH处理后, 分别以表面活性剂十六烷基三甲基溴化铵(CTAB)软模板或介孔炭(Meso-C)硬模板为导向剂, 自组装合成S-β-MCM41(c)、P-β-MCM41(c)、P-ZSM-MCM41(c)、P-ZSM-C系列微孔/介孔复合分子筛. 考察了沸石分子筛种类、碱处理液浓度以及介孔模板剂对合成复合分子筛结构与性能的影响. X射线衍射(XRD)、透射电子显微镜(TEM)和氮气吸附-脱附表征结果表明产物具有微孔/介孔多级孔结构. 该材料对CO₂的吸附能力比纯微孔或介孔材料均有明显提高, 其中P-ZSM-MCM41(2)的CO₂吸附容量最大可达1.51 mmol·g^-1, 为ZSM-5沸石吸附量的两倍多.     

立方介孔相含钕氧化硅的合成与表征

以十六烷基三甲基溴化铵为结构导向剂，通过水热法合成了具有立方结构的含钕Nd-MCM-48介孔分子筛材料。XRD和TEM测试表明当n_Nd/n_Si<0.05时可以获得典型的长程有序介孔立方结构相，随n_Nd/n_Si比的增加，晶胞参数的增大和红外吸收光谱(FT-IR)的变化为Nd进入介孔分子筛骨架中提供了有力证据。N₂吸附-脱附实验给出了其BET表面积为1 195 m²·g^-1，BJH平均孔径为3.6 nm。紫外-可见漫反射光谱(UV-Vis)证明钕氧形成一种八面体结构。X射线光电子能谱(XPS)进一步证明钕主要以三价形式存在于立方介孔分子筛骨架中。     

MCM-41负载S2O82-/TiO2固体超强酸的制备和酯化性能研究

采用液相沉积法制备了由MCM-41介孔分子筛负载S₂O₈^2-/TiO₂的固体超强酸催化剂。探讨了成酸机理，并以乙酸和异戊醇的酯化反应作为探针反应考察了焙烧温度、浸渍溶液浓度等制备条件对催化剂催化活性的影响，得到了较佳的制备条件。XRD、N₂吸附-脱附和FTIR结果表明，固体超强酸保持了MCM-41的介孔结构，BET表面积高达211 m²·g^-1，且具有强酸性(H_o<-12.70)。     

A highly stable and active mesoporous ruthenium catalyst for ammonia synthesis prepared by a RuCl3/SiO2-templated approach

Molecular nitrogen is relatively inert and the activation of its triple bond is full of challenges and of significance. Hence, searching for an efficiently heterogeneous catalyst with high stability and dispersion is one of the important targets of chemical technology. Here, we report a Ba-K/Ru-MC catalyst with Ru particle size of 1.5–2.5 nm semi-embedded in a mesoporous C matrix and with dual promoters of Ba and K that exhibits a higher activity than the supported Ba-Ru-K/MC catalyst, although both have similar metal particle sizes for ammonia synthesis. Further, the Ba-K/Ru-MC catalyst is more active than commercial fused Fe catalysts and supported Ru catalysts. Characterization techniques such as high-resolution transmission electron microscopy, N₂ physisorption, CO chemisorption, and temperature-programmed reduction suggest that the Ru nanoparticles have strong interactions with the C matrix in Ba-K/Ru-MC, which may facilitate electron transport better than supported nanoparticles.     

Preparation and characterization of supports with a synthesized layer of catalytic filamentous carbon: III. Synthesis of carbon nanofibers on nickel supported onto aluminum oxide

The synthesis of catalytic filamentous carbon (CFC) on catalysts prepared by supporting Ni²⁺ compounds onto the surface of various alumina modifications (macroporous α-Al₂O₃ and mesoporous ?-Al₂O₃ and δ-Al₂O₃) using two procedures (impregnation and homogeneous precipitation) was studied. The texture characteristics (specific surface area and pore structure) of the parent supports and adsorbents with a CFC layer were compared. The effect of the supporting procedure on the surface morphology of Ni/Al₂O₃ catalysts and the synthesized CFC layer was studied by scanning electron microscopy. It was found that the carbon yield on a macroporous catalyst prepared by homogeneous precipitation was higher than that on a catalyst prepared by impregnation by a factor of ～2. The CFC layer exhibited a mesoporous structure because of a chaotic interlacing of carbon nanofibers, and the synthesis of CFC on macroporous supports resulted in the formation of a bidisperse pore structure of the adsorbent. Active and stable heterogeneous biocatalysts were prepared by the adsorptive immobilization of enzymatically active substances (glucoamylase and nongrowing baker’s yeast cells) on CFC.     

Effect of the graphitic degree of carbon supports on the catalytic performance of ammonia synthesis over Ba-Ru-K/HSGC catalyst

A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.     

Preparation of monodispersed microporous SiO2 microspheres with high specific surface area using dodecylamine as a hydrolysis catalyst

A novel and simple method for the synthesis of monodispersed microporous SiO₂ microspheres with high specific surface area was developed by hydrolysis of tetraethoxysilane (TEOS) in a water-ethanol mixed solution and using dodecylamine (DDA) as hydrolysis catalyst and template. The as-prepared products were characterized with differential thermal analysis-thermogravimetry, scanning electron microscopy, high-resolution transmission electron microscopy, small angle X-ray diffraction and nitrogen adsorption. The effects of experimental conditions including hydrolysis temperatures, calcination temperature and concentrations of TEOS and DDA on the morphology and pore parameters of the as-prepared SiO₂ microspheres were investigated and discussed. The results showed that hydrolysis temperature and concentrations of TEOS and DDA are important parameters for the control of size and morphology of particles. The specific surface area and specific pore volume of the as-prepared SiO₂ microspheres increased with increasing DDA concentration and calcination temperature. DDA may act not only as a good hydrolysis catalyst but also as a template for the formation of monodispersed SiO₂ microspheres with high specific surface area. This research may provide new insight into the synthesis of monodispersed microporous SiO₂ microspheres.     

Core-shell structured nanospheres with mesoporous silica shell and Ni core as a stable catalyst for hydrolytic dehydrogenation of ammonia borane

Core-shell structured nanospheres with mesoporous silica shell and Ni core (denoted as Ni@meso-SiO₂) are prepared through a three-step process. Monodispersed Ni precursors are first prepared, and then coated with mesoporous SiO₂. Final Ni@meso-SiO₂ spheres are obtained after calcination. The products are characterized by X-ray powder diffraction, transmission electron microscopy and N₂ adsorption-desorption methods. These spheres have a high surface area and are well dispersed in water, showing a high catalytic activity with a TOF value of 18.5, and outstanding stability in hydrolytic dehydrogenation of ammonia borane at room temperature.     

Sol–gel synthesis of mesoporous silicas containing albumin and guanidine polymers and its application to the bilirubin adsorption

The organic–inorganic composite materials based on mesoporous silica were synthesized using sol–gel method. The surface area of silicas was modified by bovine serum albumin (BSA) and guanidine polymers: polyacrylate guanidine (PAG) and polymethacrylate guanidine. The mesoporous silicas were characterized by nitrogen adsorption–desorption analysis, Fourier transform infrared spectroscopy, transmission electron microscopy. The obtained materials were used as adsorbents for selective bilirubin removal. It was shown that the structural properties and surface area of modified materials depend on the nature of polymers. Incorporation of polymers in silica gel matrix during sol–gel process leads to the formation of mesoporous structure with high pore diameter and a BET surface area equals to 346 m²/g for SiO₂/BSA and 160 m²/g for SiO₂/PAG. Analysis of adsorption isotherms showed that modification of silica by BSA and guanidine polymers increases its adsorption ability to bilirubin molecules. According to Langmuir model, the maximum bilirubin adsorption capacity was 1.18 mg/g.     

High-loading Pt nanoparticles on mesoporous carbon with large mesopores for highly active methanol electro-oxidation

High metal-loading Pt/C electrocatalysts are important for the fabrication of thin-layered membrane electrode assemblies (MEAs). However, the preparation of high-loading Pt catalysts with a narrow size distribution of nanoparticles remains a challenge. Herein, ordered mesoporous carbon (OMC) with large mesopores (~15 nm) and a high surface area (1316.0 m² g^?1) was fabricated using a SiO₂ nanosphere array as a template. This material was developed to support a high loading of Pt nanoparticles (60 wt%) and was then used as an electrocatalyst for the methanol oxidation reaction (MOR). The prepared Pt/OMC contains Pt nanoparticles with an average size of ~1.9 nm that are uniformly dispersed on the mesoporous walls of the OMC. The Pt/OMC catalyst exhibits smaller Pt nanoparticle size, greater Pt dispersion, larger specific electrochemically active surface area (ECSA), and higher electrocatalytic activity for the MOR than the carbon black (Vulcan XC-72R)-supported Pt and the commercial Pt/C catalysts.     

Phosphotungstic acid supported on mesoporous carbon as a catalyst for the oxidation of benzyl alcohol

Phosphotungstic acid (PTA) was successfully supported on synthesized mesoporous carbon (MC) through impregnating method to yield a series of PTA/MC catalysts, the content of PTA from 16 to 43 wt %. The catalysts were characterized by FTIR spectroscopy, X-ray diffraction, N2 adsorption-desorption isotherm tests and transmission electron microscopy. The characterization data revealed that intact Keggin ion of PTA is kept in the support, and PTA is located equably inside the pores of MC. The catalytic activities of these catalysts were tested in selective oxidation of benzyl alcohol to benzaldehyde using 30% hydrogen peroxide as oxidant. The results indicated that 28 wt % PTA/MC catalyst with high specific surface area (474 m²/g) and uniform pore size (6.4 nm) possess the best catalytic activity (conversion of 82.6% and selectivity of 94.0%) among all prepared catalysts.     

Self‐organized Ruthenium–Barium Core–Shell Nanoparticles on a Mesoporous Calcium Amide Matrix for Efficient Low‐Temperature Ammonia Synthesis

A low‐temperature ammonia synthesis process is required for on‐site synthesis. Barium‐doped calcium amide (Ba‐Ca(NH₂)₂) enhances the efficacy of ammonia synthesis mediated by Ru and Co by 2 orders of magnitude more than that of a conventional Ru catalyst at temperatures below 300 °C. Furthermore, the presented catalysts are superior to the wüstite‐based Fe catalyst, which is known as a highly active industrial catalyst at low temperatures and pressures. Nanosized Ru–Ba core–shell structures are self‐organized on the Ba‐Ca(NH₂)₂ support during H₂ pretreatment, and the support material is simultaneously converted into a mesoporous structure with a high surface area (>100 m² g⁻¹). These self‐organized nanostructures account for the high catalytic performance in low‐temperature ammonia synthesis.     

晶种协同廉价有机模板导向合成高纯度MCM-49沸石

采用廉价低毒性的环己胺（CHA）作为有机模板剂,并合理添加少量MCM-49沸石晶种,在静态水热条件下成功合成了高纯度MCM-49沸石.研究了起始凝胶组成（如Al₂O₃/SiO₂,H₂O/SiO₂,CHA/SiO₂,晶种/SiO₂,Na₂O/SiO₂）、晶化温度和时间等因素对合成MCM-49沸石的影响.通过XRD、SEM、N₂吸附、固体²⁷Al和²⁹Si MAS NMR等手段表征产物,结果表明合成的MCM-49沸石具有良好的结晶度、均匀的晶体尺寸、高比表面积和纯的四配位Al³⁺物种.热重差热分析（TG-DTA）和固体¹³C MAS NMR表征结果证实CHA是作为模板剂填充在沸石产物的孔道内.这种合成MCM-49的方法具有廉价和低毒性的特点,对其产业应用有潜在的重要价值.