不同热处理方式对超细粒子K—Co—Mo催化剂性能和结构的影响

以柠檬酸为络合剂,采用溶胶-凝胶法制备Co-Mo超细粒子氧化物,所得干凝胶分别置于空气和氩气中进行焙烧,然后经K2CO3助化后硫化。使用X射线衍射（XRD）比表面测试和扩展X光吸收精细结构（EXAFS）对样品进行结构表征,同时测试硫化态样品的CO加氢合成低碳混合醇活性。XRD结果表明,在空气中焙烧的样品为单一的CoMoO4物种,其晶粒尺寸约为60nm。在氩气中焙烧的样品,柠檬酸的分解对样品起到还原作用,主要物种为CoMoO3,同时存在少量的CoMoO4,晶粒尺寸约为20nm。BET结果表明,在氩气中焙烧的样品具有较大的比表面积。硫化态样品中主要物种为MoS2和Co9S8,此外,还可能存在CoMoS3.13物种。XRD和EXAFS结果均表明,在氩气中焙烧的样品硫化后,其晶粒尺寸相对较小。活性测试结果表明,催化剂晶粒尺寸的降低明显促进了合成醇的活性和选择性的提高。     

加热过程中古代铜镜表面"锡汞齐"相变分析

利用可在常温至1 200℃下,对样品进行边加热边检测的θ-θ扫描(立式测角仪)密封陶瓷X射线管全自动衍射仪及X射线荧光,再结合表面形貌特征等对涂抹"锡汞齐"的高锡铜镜样品进行了检测分析,证明在加热到高于Hg的沸点时含汞物相会逐渐消失;说明铜镜或青铜器表层中有无Hg不能作为判断其是否采用过"锡汞齐"工艺的依据,并且从使用角度来看,铜镜涂抹"锡求齐"也没有必要.     

原子力显微镜与x射线光电子能谱对LiBq4/ITO和LiBq4/CuPc/ITO的表面分析

利用原子力显微镜对8-羟基喹啉硼化锂(LiBq4)/铟锡氧化物和8-羟基喹啉硼化锂/酞菁铜(CuPc)/铟锡氧化物表面分别进行了扫描,显示了LiBq4在不同衬底上的形貌差异,并进一步利用样品表面的x射线光电子能谱图验证了这一差异.实验表明,CuPc层的加入改善了LiBq4的成膜质量,并将这种改善归因于分子构型与电子亲和势的不同.     

Preparation and Acid Catalytic Activity of TiO2 Grafted Silica MCM-41 with Sulfate Treatment

采用连续嫁接方法对纯硅MCM-41孔道表面分别进行一次和两次TiO2修饰，并进行了硫酸根促进，制备了具有规整介孔结构的硫酸根促进型复合金属氧化物ST/MCM-41和d-ST/MCM-41；同时制备了经一次钛修饰但未经硫酸根促进的样品T/MCM-41作为对比. 利用XRD、氮吸附-脱附、元素分析、拉曼光谱和红外光谱等表征手段，对所制样品的结构和表面酸性进行考察；利用假性紫罗兰酮环化这一典型的酸催化反应对其催化活性进行评价，并与工业应用的大孔磺酸树脂Amberlyst-15进行催化性能比较. 表征结果显示，纯     

锡汞齐工艺中Hg对铜镜的影响

采用X射线衍射、扫描电镜等实验手段,对涂抹锡汞齐的青铜样品进行分析,讨论Hg在铜镜表面处理过程中可能会产生的作用,证明铜镜中Hg并不能完全挥发,残留的Hg在铜镜中会不断扩散,最终使铜镜表面逐渐模糊,不能用于映照。     

微量Na元素掺杂对SnSe多晶材料热电性能的影响（英文）

熔炼方法制备微量掺杂多晶硒化锡NaxSn1-xSe(x=0.001-0.005)热电材料,并研究其热、电输运性质.研究结果表明:对硒化锡进行Na元素轻掺杂(x=0.003)时,掺杂样品的电导率有了两个数量级的提高,同时其热导率也有一定的降低;而且掺杂后的样品还拥有很高的Seebeck系数,Seebeck最大能达到300V/K左右.因此硒化锡掺钠多晶Na0.003Sn0.997Se的ZT值能达到1.2左右.     

焙烧高岭土的相变研究

对湿化学方法处理过的高岭土作不同温度焙烧得不同样品，对不同样品进行XRD研究表明，高岭土随焙烧温度的不同发生一系列相应。用DTA，TG，IR对其相变进行了印证，得到了一致的结果。     

熔化状态下锡样品微喷射现象的诊断北大核心CSCD

强冲击熔化状态下,金属样品表面微喷射大幅增加,难以诊断。针对该问题,利用Asay-F窗技术,通过实验诊断,得到了熔化状态下不同表面加工状态锡样品表面微喷射物质的质量、密度、速度和空间分布等信息,分析了表面加工状态对表面喷射物质量及特征的影响。结果发现,对于熔化状态的金属样品,表面粗糙度仍是决定微喷射物质量大小、速度及空间分布的重要因素,且相关特征均呈现随表面粗糙度增大而增大的趋势。研究结果为认识熔化状态下材料的微喷特性及构建物理模型提供了重要数据。     

FT-IR与微量吸附量热联用研究BaO/Al_2O_3催化剂表面酸碱性质

运用红外光谱与微量吸附量热联用技术研究了焙烧温度对BaO/γ-Al2O3表面酸碱性的影响。结果表明,γ-Al2O3经1000℃焙烧转化为θ-Al2O3和α-Al2O3,BaOγ-Al2O3经高温焙烧后生成BaO·Al2O3和BaO·6Al2O3等物相。600℃焙烧后,BaO/γ-Al2O3的表面酸性比γ-Al2O3的稍有下降,而碱性却大为增强。经1000℃焙烧后,表面的酸碱性则均大为降低,只有少量较弱的酸碱性位。     

熔化状态下锡样品微喷射现象的诊断

强冲击熔化状态下,金属样品表面微喷射大幅增加,难以诊断。针对该问题,利用Asay-F窗技术,通过实验诊断,得到了熔化状态下不同表面加工状态锡样品表面微喷射物质的质量、密度、速度和空间分布等信息,分析了表面加工状态对表面喷射物质量及特征的影响。结果发现,对于熔化状态的金属样品,表面粗糙度仍是决定微喷射物质量大小、速度及空间分布的重要因素,且相关特征均呈现随表面粗糙度增大而增大的趋势。研究结果为认识熔化状态下材料的微喷特性及构建物理模型提供了重要数据。     

Synthesis and characterization of MCM-41 decorated with CuO particles

CuO particles have decorated on the external surface of MCM-41 by in situ introducing cupric nitrate during the hydrothermal synthesis followed by the calcination. The textural and structural properties of CuO/MCM-41 are compared with those of pure MCM-41. The results show that CuO particles are about 40 nm in size and are not agglomerated. The addition of cupric nitrate to the synthesis gel leads to materials with somewhat reduced quality as evidenced from X-ray diffraction patterns and nitrogen adsorption measurements. CuO/MCM-41 is less ordered relative to pure MCM-41 and there are inter-aggregate pores resulting in a higher average pore diameter in the material. The formation of CuO particles on the external surface of MCM-41 and the possible reason for the less ordered structure of CuO/MCM-41 are also discussed in the present paper.     

Key factor affecting the structural and textural properties of ZSM-5/MCM-41 composite

ZSM-5/MCM-41 micro/mesoporous composite materials were synthesized by the hydrothermal technique with alkali-treated ZSM-5 zeolite as source of silica and aluminum and characterized by various physico-chemical techniques such as X-ray diffraction (XRD), nitrogen sorption at 77 K, transmission electronic microscopy (TEM), FTIR spectroscopy and NH₃ temperature programmed desorption (TPD) techniques. The effect of concentration of CTAB in the synthesis of these solids has been investigated, the mesopore volume, surface area and surface acidity decrease with increasing the concentration of CTAB. Increasing the CTAB concentration causes the recrystallization of zeolite ZSM-5 and it disadvantage the formation of mesoporous materials MCM-41. The catalytic activity of ZSM-5/MCM-41 materials has been evaluated in the Friedel–Crafts acylation of anisole with benzoyl chloride as alkylating agent. The results revealed the reaction to be influenced by surface area, pore volume and surface acidity.     

Synthesis and characterization of a hexagonal mesoporous silica with enhanced thermal and hydrothermal stabilities

A synthetic route was developed for a novel hexagonal mesoporous silica that has remarkably wide channel diameters and thick walls. The procedure involved the acid-catalyzed hydrolysis of tetraethylorthosilicate in a water/ethanol/isopropoanol solvent mixture while employing 1-hexadecylamine as a templating agent and mesitylene as an auxiliary agent. After removal of the template by either extraction with ethanolic hydrochloric acid or by calcination at 550 °C, the resulting mesoporous materials had surface areas of 1283 and 1211 m²/g. The channel diameters were found to be 47.2-51.1 Å, while the wall thicknesses were 20.9-21.1 Å. X-ray powder diffraction demonstrated that the novel mesoporous silica belonged to the MCM-41 structural family. Notably, they displayed higher thermal and hydrothermal stabilities, and have higher surface areas than conventionally prepared MCM-41 silica. The thickest channel walls (21.1 Å) can withstand calcination to nearly 850 °C with minimal structural damage. The calcined sample was more resistant to hydrothermal treatment in boiling water than was the solvent-extracted product but both materials showed minimal change after 25 h of hydrothermal treatment.     

Surface properties of mesoporous catalytic supports

The influence of the processing parameters on the properties of zirconia, alumina and silica MCM-41 has been investigated. Digestion of the precursors leads to zirconia, alumina and silica MCM-41 with higher surface area and better thermal stability. The effects of digestion are attributed to increased dehydroxylation, strengthening of the network between primary particles, and to a decrease in the number of surface defects. In the case of zirconia and alumina, digestion also increased the surface acidity. This may be due to the smaller crystallites which expose low-coordinated sites at the surface. Al-MCM-41 prepared by post-synthesis grafting of aluminum is compared with MCM-41 prepared by direct incorporation of aluminum during synthesis. The surface Si/Al ratio was determined using XPS and correlated to the catalytic activity of the Al-MCM-41 for the synthesis of jasminaldehyde.     

Optical properties of (nanometer MCM-41)-(malachite green) composite materials

Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman spectra firmly demonstrated the stable form obtained after the MG incorporation into the nanometer MCM-41. Therefore, nanometer MCM-41 appears to have a good potential for its use as a support for dyes and the (nanometer MCM-41)-MG composite materials may give a wide optical application.     

Synthesis of hematite nanowires using a mesoporous hard template

The influence of the impregnation media (ethanol or water) and the calcination atmosphere (air and NO/He) on the hematite nanowires production embedded on a hard template (MCM-41) was studied. The solids were characterized by X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. The results obtained indicate that the more appropriate conditions for the iron oxide nanowires to get inside the MCM-41 hard template seem to be reached using water as a solvent and air as calcination atmosphere.     

MCM-41负载磷钨酸的制备与表征

以十六烷基三甲基溴化铵(CTAB)为表面活性剂,以正硅酸乙酯(TEOS)为硅源,采用水热合成法制备了介孔分子筛MCM-41,并利用浸渍法将磷钨酸(HPW)负载在MCM-41分子筛上,得到HPW/MCM-41催化剂f采用X射线衍射、傅里叶变换红外光谱、透射电镜等手段对负载型催化剂进行了表征.结果表明,磷钨酸负载到MCM-...     

Effect of the thermal and hydrothermal treatment on textural properties of Zr-MCM-41 mesoporous molecular sieve

Zr-containing mesoporous molecular sieves were synthesized by hydrothermal method using cetyltrimethyl ammonium bromide as a template and sodium silicate and zirconium sulfate as raw materials. The structure and morphology of the synthesized samples were characterized via various physicochemical methods, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, solid state nuclear magnetic resonance (²⁹Si MAS-NMR) techniques, thermal gravimetric-differential scanning calorimeter (TG-DSC) and N₂ physical adsorption, respectively. The effect of the different initial ZrO₂:SiO₂ molar ratio, the different thermal treatment temperature and the different hydrothermal treatment time on textural property was investigated. The experimental results reveal that the as synthesized samples possess a typical mesoporous structure of MCM-41. On the other hand, the specific surface area and pore volume of the synthesized Zr-MCM-41 mesoporous molecular sieve decrease with the increase of the amount of zirconium incorporated in the starting material, the rise of thermal treatment temperature and the prolonging of hydrothermal treatment time, the mesoporous ordering becomes poor. Also, when the molar ratio of ZrO₂:SiO₂ in the starting material is 0.1, the mesoporous structure of the Zr-MCM-41 mesoporous molecular sieve still retains after calcination at 750 °C for 3 h or hydrothermal treatment at 100 °C for 6 d, and have specific surface areas of 423.9 and 563.9 m²/g, respectively.     

Stability and textural properties of cobalt incorporated MCM-48 mesoporous molecular sieve

Transition metal cobalt incorporated MCM-48 mesoporous molecular sieves (CoMCM-48) with different Co contents were synthesized hydrothermally at 120 °C for 24 h by directly adding fluoride ions to the initial gel. The resulting materials were characterized by means of XRD, TEM, FT-IR, UV-vis, TPR and N₂ physical adsorption, respectively. The effect of various factors, such as the Si/Co molar ratio, calcination temperature and hydrothermal treatment time, on the crystalline structure and textural properties of CoMCM-48 was investigated in detail. The results show that the CoMCM-48 mesoporous materials with high specific surface area were successfully synthesized. A small amount substitution of Co for Si in MCM-48 did not significantly change the textural properties while the higher cobalt incorporated leads to decrease of the surface area and deterioration of structural regularity. Furthermore, the resulting CoMCM-48 still retained the cubic mesoporous framework even after calcination at 800 °C for 4 h or hydrothermal treatment at 100 °C for 24 h.     

荧光光谱法研究左氧氟沙星与MCM-41的相互作用

采用微波辅助水热法制备介孔分子筛MCM-41,并用浸渍法将左氧氟沙(LVFX)组装在MCM-41均一的六方形孔道中,制备出新型载药复合物LVFX/MCM-41.用粉末X射线衍射(XRD)、低温氮吸附、傅里叶变换红外光谱(FTIR)及差热-热重(TGA-DTA)分析对MCM-41以及LVFX/MCM-41复合物进行表征,合成的介孔分子筛MCM-41的孔径为2.382 nm,比表面积为1 015 m2·g-1.对MCM-41、LVFX/MCM-41、LVFX(固态)及LVFX(溶液)的荧光光谱研究结果显示,LVFX/MCM-41的荧光光谱比组装前发生明显红移,表明MCM-41孔道内表面的羟基和LVFX形成氢键,羟基上的电子云向LVFX分子上的吸电子基团转移;同时MCM-41和LVFX之间形成新环,使电子云能在更大的环上移动,药物分子的共轭体系扩大,荧光光谱峰红移.MCM-41与左氧氟沙星之间强的相互作用为研发以MCM-41为载体的新型释药系统提供了理论依据.