碱土—稀土氧化物在甲烷偶联反应中的催化性能

研究了两个典型轻稀土Ｌａ，Ｃｅ氧化物对甲烷氧化联反应的影响，具有较小比表面积的催化给出较高的Ｃ２选择性，但是催化剂的氧化还原性能对Ｃ２选择性的影响则更大，添加Ｌｉ的作用除产生Ｏ中心外，还可抑制催化剂的氧化还原能力，从而改善Ｃ２选择性，甲烷氧化偶联反应属催化剂引发的自由基反应。     

碱土金属离子(Mg2+,Ca2+,Ba2+)掺杂对长余辉荧光粉SrAl2O4:Eu2+,Dy3+发光性能的影响

采用高温固相法制备了碱土金属离子(Mg2 ,Ca2 ,Ba2 )掺杂的SrAl2O4:Eu2 ,Dy3 长余辉荧光粉.XRD谱分析表明,随着基质中掺人的碱土金属离子(Mg2 ,Ca2 ,Ba2 )浓度增加,基质晶格常数也随之发生变化.Mg2 ,Ca2 和Ba2 3种碱土离子在SrAl2O4中的固溶范围分别为40%,15%和30%.光谱分析则表明在固溶范围内随着掺杂Mg3 ,Ca2 和Ba2 浓度的增大,样品的发射峰值会在480～530 nm范围出现规律性移动.适当浓度的Mg2 ,Ba2 掺杂会不同程度地提高样品的发光强度,而Ca2 的掺杂则会降低发光强度.但是碱土金属离子(Mg2 ,Ca2 ,Ba2 )的掺杂并不能延长SrAl2O4:Eu2 ,Dy3 荧光粉的余辉时间.     

单组分稀土聚合催化剂研究进展

对７７篇代表性文献综述了单组分稀土聚合催化剂的最新进展,重点介绍这一催化剂的主要特征,并指出了有待解决的几个问题。     

稀土氧化物固体碱催化剂的表面性质Ⅰ．稀土氧化物表面活性中心的表征

采用ＴＰＤ－ＭＳ，ＩＲ等技术研究了Ｌａ２Ｏ３，Ｙ２Ｏ３，Ｎｄ２Ｏ３，ＣｅＯ２及参照氧化物Ａｌ２Ｏ３，ＺｒＯ２，ＭｇＯ表面的酸碱性，氧活性及表面羟基．结果表明，上述稀土氧化物表面上不仅存在着两种碱中心，还有酸中心存在，且其表面都存在活性氧中心，表面的性质同碱土氧化物ＭｇＯ类似，但与Ａｌ２Ｏ３，ＺｒＯ２等有较大差别     

固体碱催化剂

综述了最近30年来固体碱催化剂的研究现状，包括固体碱催化剂的种类、优缺点以及各类催化剂中影响其催化性能的因素。重点探讨了碱性前驱体和载体对负载型无机固化碱碱强度的影响，展望了未来固体碱剂的发展方向。     

稀土形态与FCC催化剂性能关系的研究

采用IR羟基表征、XRD、微型和小型反应器等手段研究了不同形态稀土在FCC催化剂中的应用.实验结果表明,在分子筛制备过程中以沉淀方式引入的稀土,部分以独立相形式存在,具有抗钒污染的性能,对催化剂活性和裂化产物分布影响不大,这与以交换方式引入分子筛中的稀土对催化剂的影响不同.     

二氧化碳甲烷化Ni—Ru—稀土／ZrO2催化剂的活性研究

用浸渍法制备了一系列的Ｎｉ－Ｒｕ－稀土／ＺｒＯ２三组分担载型二氧化碳甲烷化催化剂，并利用固定床反应器对其催化性能进行了研究。实验结果表明，添加稀土后的三组份催化剂具有较高的催化活性，含稀土催化剂的活性与稀土离子的４ｆ电子数有关，稀土元素的磅笥对催化剂性能有一定的影响，不同催化剂的反应表观活化能大小次诒有催化剂活性次序相等。     

原子发射光谱法间接测定黄连素片剂中盐酸小檗碱的研究

本文提出了离子对-原子发射光谱间接测定黄连素片剂中盐酸小檗碱的新方法。发现用1,2-二氯乙烷作萃取剂效果最佳。用此怯测定实际样品的结果与药典法一致,相对误差为0.61％,单一测定的相对标准偏差为0.67％。本法还可在盐酸普鲁卡因共存下单独测定盐酸小檗碱。方法可靠、适用,选择性较好。     

Emission Spectra of Some Heteropolytungstates Containing Europium

The emission spectra of some heteropolytungstates containing europium, K.[Eu(XW11 O39)2](X = P, Ge, As, or Ga), K17[EuCAs2W17O61)2] and K16H9EuAs4W40O140 have been investigated and the structures of these compounds are discussed. The emission spectra at room temperature are very similar to each other in terms of both the number of bands and transition frequencies, showing that they have the similar structures to those of K16[Ce(P2W17O61)2] and K12[U(GeW11O39)2].     

Oxidative Methylation of Toluene with Methane over Basic Zeolite Catalysts Promoted with Alkali Metal Bromides and Alkali Metal Oxides

IntroductionStyrene is one of the most important industrial monomers. At present, styrene is mainlyproduced by alkylation of benzene with ethylene followed by oxidative dehydrogenationof the resulting ethylbenzene. However, this process is very expensive and complex. Anew method of synthesizing ethylbenzene and styrene directly from toluene and methanewas discovered by Khcheyan el al. ', and Yakovich and Bakareva2. The process wouldpotentially reduce the cost because of the production of sty…     

Studies of the Effects of Alkali Metal Oxides Promoter on the Oxidative Methylation of Toluene with Methane over KY Zeolite Catalysts

Methane is the most abundant component of natural gas. The direct conversion of methane into chemical feedstock or transportable liquid fuel is an attractive process. In addition to oxidative coupling of methane, oxidative methylation of toluene with methane to styrene and ethylbenzene which has been investigated by Khcheyan et al.1, provides another possibility of methane utilization. Recently, several research groups have employed some metal oxides for the oxidative methylation of toluene w…     

Partial Oxidation of Butane to Syngas over Nickel Supported Catalysts Modified by Alkali Metal Oxide and Rare-Earth Metal Oxide

There are abundant supplies of mixture gases containing CH4, C2H6, C3H8 and C4H10, etc. from FCC (Fluidized Catalytic Cracking) tail gas, refinery gas, etc. Commonly, the mixture gases are primarily combusted to carbon dioxide because the complete separation of CH4, C2H6, C3H8 and C4H10, respectively, from the mixture gases may not be economical. Provided that syngas (CO+H2) could be produced from the mixture gases over nickel supported catalysts with high selectivity and conversion,…     

ChemInform Abstract: Quantum Molecular Interpretation of Photodetachment and Photodepletion Spectra of Small Alkali Metal Clusters.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

傅里哀变换红外发射光谱法研究金属氧化物催化剂 I. 实验建立及氧化钼的还原-氧化研究

本文报导了傅里哀变换红外发射光谱法研究多相氧化物催化剂的实验装置的建立及实验条件的考察。设计加工了一个温度范围宽, 可在各种气氛和真空条件下原位研究氧化物催化剂的红外发射池。以MoO_3为例, 考察了样品厚度, 测试温度对发射光谱的影响。当样品量小于1 mm·cm~(-2)时, 随样品量增加, 谱峰强度线性增加, 但峰形不发生变化。当样品量高于1 mg·cm~(-2)时, 随样品量增加, 谱图严重畸变。随样品温度升高,谱峰强度近似线性增加。并用该方法研究了MoO_3在还原和再氧化过程中表面氧物种的变化。结果表明桥式MO—O—Mo物种比端基Mo=O物种较易还原, 再氧化时, Mo=O物种比Mo—O—Mo物种优先形成。     

有机银溶胶的吸收光谱和表面增强Raman光谱研究

研究了2-氨基苯并咪唑(BIMNH₂)、LiCl、NaOEt对Ag/EtOH溶胶吸收光谱和表面增强Raman散射(SERS)光谱的影响。结果表明,少量的吸附分子BIMNH₂、LiCl、NaOEt均能改变溶胶聚集状态,从而影响其吸收光谱和SERS效应。此外,Cl^-还可与Ag、BIMNH₂形成表面络合物而增强SERS效应。对Ag溶胶体系SERS光谱的溶剂效应也作了初步研究。     

Pt基催化剂对金属氧化物助催化作用

介绍金属氧化物修饰Pt基催化剂作为直接甲醇燃料电池用阳极催化剂的研究工作,重点阐述了催化剂的结构和组成对反应机理的影响,探讨了存在的主要问题和发展前景.     

Solvent Effect on the Absorption and Fluorescence Emission Spectra of Some Purine Derivatives: Spectrofluorometric Quantitative Studies

The absorption and emission spectra of six purine derivatives: adenine (I), N(9)-hydroxyethyladenine (II), N(6)-acetyladenine (III), N(6)-isobutyryladenine (IV), guanine (V), and N(2),N(9)-diacetylguanine (VI) have been investigated. The effects of solvent and pH on the positions of λ _max (absorption) and λ _max (emission) of these compounds were determined. Correlations between the absorption wavelength (λ _max) of these organic compounds and the solvent parameters (D,n,E) or (K,M,N) show that the peak position is affected mainly by specific- and non-specific types of interactions between the solvent and solute. Solvent effects on the electronic absorption band shifts are indicative of the extent of charge reorganization of the solute molecules upon electronic excitation. The Stokes shift (ν _abs−ν _em) was correlated with the orientation polarizability (Δf) and was found to depend mainly on the dielectric constant and the refractive index of the solvents. This shift reflects the influence of the equilibrium solvent arrangement around the excited solute molecule, which rearranges inertially due to the instantaneous charge redistribution upon radiative deactivation to the electronic ground state. A spectrofluorometric analysis technique was applied for the quantitative analysis of the components of a ternary mixture of compounds (I–III).     

过渡金属络合物荷移光谱的研究

在配位场近似下,用不可约张量方法对具有O_4对称性的FeCl_6~(3-)及与其结构相似的过渡金属络合物的Hamilton矩阵进行了矩阵分割,得到了一种计算荷移光谱的简单方法.在计算中采用方案,考虑了纯组态内部的Coulomb作用和旋轨作用,忽略了不同组态间的Coulomb作用.并采取冻结轨道近似.计算结果与实验光谱数据符合较好.