双组分载体铂重整催化剂的制备及性能研究

通过改变铂重整催化剂的载体组分制备出一系列催化剂．采用连续微反色谱考察了各催化剂对正己烷和环乙烷重整反应的活性和选择性．发现在ＨＺＳＭ—５和ＨＹ载体中引入适量的γ－Ａｌ２Ｏ３，能有效地改变催化剂的活性和选择性．     

硼砂-芦荟大黄素光度测定新方法

借助硼砂与芦荟大黄素的显色反应,利用可见分光光度法,提出了测定芦荟大黄素含量的新方法.芦荟大黄素的测定下限为0.0005g/L.此方法重复性好,样品分析结果相对标准偏差小于7%,加标回收率92%～110%.     

由层状钛酸盐纳米管制备SrTiO3纳米粒子及其表征

采用水热法,使用层状钛酸盐纳米管和乙酸锶作为前驱物,在一定反应温度和时间的条件下,制备了SrTiO3纳米粒子.采用X射线粉末衍射(XRD),扫描电镜(SEM),透射电镜(TEM),拉曼光谱(Raman),激发光谱(PL)和比表面积分析等测试技术对SrTiO3纳米粒子进行了表征.测试结果表明,只有在反应条件和反应前驱物配比适当时才能制备得到纯的无序多孔SrTiO3纳米粒子,粒径主要分布在10～30nm之间,无明显团聚现象;随着反应时间的延长或者反应温度的升高,粒径趋于增大,而比表面积趋于减小,对亚甲基蓝在紫外光照下的光降解活性也随之降低.     

SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION

In this paper,the influence of crystal-field on the Luminescence properties of Eu~(2 ) in complex oxidesare studied theoretically by using purely electrostatic model,the dependence of the 4f~65d levels on Eu-Obond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f~65d energy band incubic or in octahedral fields will be inversely proportional to R~5,where R is the distance of Eu~(2 ) to oxygenligand.The value of R affects slightly the location of the centre of 4f~65d energy band.According to the exper-imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites ofEu~(2 ) and degree of covalency of Eu-O bond on luminescence properties of Eu~(2 ).Some regularity offluorescence spectrum was observed.In alkali-alkaline earth-phosphates,the splitting extent of 4f~65d band (△E) becomes smaller as theEu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emissionpeak of Eu~(2 ) will shift to shorter wavelength with the increase of x's value.The crystal structure data show that Eu~(2 ) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-fieldand covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu~(2 ) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu~(2 )produces ultraviolet fluorescence.     

均相沉淀-发泡法制备纳米氧化钛及其表征分析

采用Ti（SO4），和尿素为原料，利用均相沉淀．发泡工艺制备出了纳米氧化钛粉体材料，并用DTA-TG、XRD、IR和FS等方法对样品进行了表征。DTA-TG结果表明TiO2样品在高温固相反应期间有两个明显的失重台阶。XRD分析表明，在500℃下焙烧的TiO2样品为相纯度较高的锐钛矿型氧化钛粉体，其平均粒径约为12．834nm。IR谱图显示随着烧结温度的升高，450～800cm^-1处Ti-O键的伸缩振动峰出现分裂，且峰形逐渐锐化，表明纳米样品的尺寸有所增大。FS分析表明在365nm激发波长下，600℃煅烧下生成的混合晶型的纳米氧化钛具有最强受激发射峰，而在393nm激发光下。500℃煅烧下生成的锐钛矿型氧化钛具有最强受激发射峰。     

有机光致变色化合物及其应用

综述了目前研究较多的几种有机光致变色化合物的光致变色反应、光变性能和研究进展,介绍了目前广受关注的双光子光致变色反应过程,以及有机光致变色化合物的应用,并展望了其发展方向.     

Pt/L重整催化剂的研究──制备条件对芳构化性能的影响

以正己烷、环己烷的转化为探针反应，考查了催化剂的制备条件对芳构化性能的影响。结果表明，经氧气焙烧的催化剂Pt／BaKL（b）具有较高的劳构化活性和选择性；最佳空速（WHSV）为3h－1；用KC1共浸法制备的催化剂（Pt＋KCl）／BaKL的催化活性比Pt／BaKL催化剂的低。     

载铂L型分子筛重整催化剂研究进展

本文对近十余年来新型载铂 L 型分子筛重整催化剂的研究状况作了较为详细的归纳与比较。着重讨论了催化剂的制备方法、栽体的酸碱性和铂的分发度对催化活性的影响。对催化机理作了初步探讨。综述文献25篇。     

Upconversion luminescence of Yb3+/Ho3+/Er3+/Tm3+ co-doped KGd(WO4)2 powders

Different lanthanide ions (Yb3+/Ho3+/Er3+/Tm3+) codoped KGd(WO4)2 phosphors were prepared by high-temperature solid-state reaction. The upconversion luminescence properties of two-ion and three-ion co-doped KGd(WO4)2 phosphors were investigated in detail. The concentration quenching effect of the two-ion co-doped KGd(WO4)2 phosphors was studied, and the optimum concentration of Ho3+, Er3+ and Tm3+ are 2 mol.%, 2 mol.% and 3 mol.%, respectively. The Yb3+/Ho3+/Tm3+ co-doped KGd(WO4)2 sample is the best white ...     

燃烧-发泡法制备不球磨SrAl2O4:Eu2+,Dy3+长余辉粉体材料

向体系内添加分散剂、燃烧剂、发泡剂和矿化剂,于低温下进行燃烧-发泡反应,一步制备了不球磨的SrAl2O4Eu2+,Dy3+长余辉粉体材料.XRD分析表明,相纯度较高,晶粒尺寸为约35.2nm.FS结果显示,产品有371.8nm、398.6nm、410.0nm和420.4nm 4个主要激发峰,发射峰位于517.2nm,余辉时间达数小时.该方法具有反应时间短,合成温度低,产物发光亮度好,不用球磨就能得到粉体的优点.