Synthesis Gas Generation by Chemical-Looping Reforming Using Ce-Based Oxygen Carriers Modified with Fe, Cu, and Mn Oxides

Chemical-looping reforming (CLR) is a technology that can be used for partial oxidation and steam reforming of hydrocarbon fuels. It involves the use of a metal oxide as an oxygen carrier, which transfers oxygen from combustion air to the fuel. Composite oxygen carriers of cerium oxide added with Fe, Cu, and Mn oxides were prepared by co-precipitation and investigated in a thermogravimetric analyzer and a fixed-bed reactor using methane as fuel and air as oxidizing gas. It was revealed that the addition of transition-metal oxides into cerium oxide can improve the reactivity of the Ce-based oxygen carrier. The three kinds of mixed oxides showed high CO and H-2 selectivity at above 800 degrees C. As for the Ce-Fe-O oxygen carrier, methane was converted to synthesis gas at a H-2/CO molar ratio close to 2:1 at a temperature of 800-900 degrees C; however, the methane thermolysis reaction was found on Ce-Cu-O and Ce-Mn-O oxygen carriers at 850-900 degrees C. Among the three kinds of oxygen carriers, Ce-Fe-O presented the best performance for methane CLR. On Ce-Fe-O oxygen carriers, the CO and H-2 selectivity decreased as the Fe content increased in the carrier particles. An optimal range of the Ce/Fe molar ratio is Ce/Fe > 1 for Ce-Fe-O oxygen carriers. Scanning electron microscopy (SEM) analysis revealed that the microstructure of the Ce-Fe-O oxides was not dramatically changed before and after 20 cyclic reactions. A small amount of Fe3C was found in the reacted Ce-Fe-O oxides by X-ray diffraction (XRD) analysis.

Tunable optical properties of nano-Au on vanadium dioxide

The optical properties of Au nanoparticles deposited on thermochromic thin films of VO2 are investigated using spectroscopy. A localized modification on the transmittance spectrum of VO2 film is formed due to the presence of Au nanoparticles which exhibit localized surface plasmon resonance (LSPR) in the visible-near IR region. The position of the modification wavelength region shows a strong dependence on the Au mass thickness and shifts toward the red as it increases. On the other hand, it was found that the LSPR of Au nanoparticles can be thermally tunable because of the thermochromism of the supporting material of VO2. The LSPR wavelength, lambda(SPR), shifts to the blue with increasing temperature, and shifts back to the red as temperature decreases. A fine tuning is achieved when the temperature is increased in a stepwise manner.

噻吩胺基稀土配合物的合成、表征

本论文共合成了两种类型12个稀土金属配合物和一个硅化合物,分别对它们进行了红外、核磁等表征，对其中的9个配合物进行了晶体结构的测定。考察了配体结构和反应条件对所生成的配合物结构的影响，研究了稀土单烷基配合物的反应性，以及稀土双烷基配合物在烷基铝和有机硼盐的共同作用下对丁二烯聚合的催化活性和选择性。主要工作内容和结论如下： (1) 合成了噻吩苯胺配体(HL1)，该配体与(Lu，Y)稀土三烷基化合物反应，通过C–H活化和烷基消除反应制备了稀土(Lu，Y)单烷基配合物1和2，配体以少见的C，N模式配位，S原子并不参与配位。配体(HL1)与Sc三烷基化合物反应制备了配体分别以C, N和N, S配位的双配的Sc配合物5。 (2) 通过改变反应时间和溶剂体系，HL1与稀土钇三烷基化合物反应可得到罕见的由稀土烷基化物和胺化物两部分组成的配合物3，它们通过噻吩环上活化的C原子连接在一起。HL1和Lu(CH2SiMe3)2(THF)2LiCH2SiMe3在甲苯和正己烷溶剂中反应可得到以L12Lu(CH2SiMe3)2为阴离子，Li(THF)4为阳离子的离子对4。 (3) 研究配合物1和2的反应性。1和2与过量的PhSiH3反应得到中心金属与Si元素交换的Si化合物。 (4) 合成了噻吩苯基膦胺配体(HL2-4)和苯基膦胺配体(HL5)配体。HL2-5与稀土(Y, Lu和Sc)三烷基化合物反应制备了稀土双烷基配合物6，7，8，9，10，11和12。进一步研究了稀土金属双烷基配合物6–12对丁二烯的催化特性，发现该系列催化剂具有独特的催化性质，能够催化丁二烯高反1，4-聚合（91.3%），得到的聚合物分子量在1到2万之间，分子量分布较窄(1.4–1.6)。 (5) 研究了金属钇(Y)，镥(Lu)，钪(Sc)三种中心金属对丁二烯聚合活性和反式1，4选择性的影响，发现催化剂对丁二烯聚合活性和反1，4选择性取决于配合物的中心金属原子，其中选择性最高为钪配合物，催化活性最佳的为钇配合物。 (6) 研究了配体HL2-4的N-芳环上的取代基分别为甲基，乙基，异丙基时催化体系对丁二烯反式1，4聚合活性和选择性的影响，发现随着N-芳环上取代基空间位阻的增大，催化剂活性逐渐下降，选择性逐渐增加，但当其取代基为异丙基时，过大的空间位阻导致活性和选择性同时有明显的下降。我们通过改变噻吩基为苯基，比较了相同聚合条件下含噻吩基的稀土双烷基配合物和含苯基的稀土双烷基配合物对丁二烯聚合活性和选择性的影响，发现噻吩环的存在对催化剂的活性和选择性有较大的影响。 (7) 在相同催化剂条件下，研究了不同聚合条件(不同类型的AlR3，不同类型的Borate，Al/Ln比等)对丁二烯反1，4聚合活性和选择性的影响。 我们发现，在AlR3和Borate这两种影响因素中，以烷基铝的类型对催化剂催化活性和选择性的影响最大，而有机硼盐的影响则比较轻微，其中以烷基铝为AliBu3，Borate为[B(C6F5)4][Me2NHPh]时，反1，4选择性为最佳。Al/Ln增大并不能够显著增加催化剂的活性，对选择性的影响也并不明显，相反，随着铝比的增加，聚合过程中的链转移增加，导致分子量下降，对于该系列稀土烷基催化剂，最佳Ln/Al 为10。

电致发光金属配合物和有机小分子的合成与性能

本文以调控发光颜色、提高发光效率为目的，通过改变配体、中心金属离子、取代基等进行颜色调节；通过引入电子或空穴传输单元，实现发光分子的功能化进而改善载流子传输提高发光效率。文中主要以有机小分子和金属配合物为研究对象，它们本身都具有良好的发光性质。工作集中围绕以下几个问题展开：1、PPV齐聚物是一类高效发光的分子体系，如果在其中嵌入8一取代的哇琳单元对发光会有什么影响？2、使用含噁二唑（具有电子传输功能）的配体得到的金属配合物是否能同时拥有双重功能，即高效发光（金属配合物的特点）和优良的电子传输？3、由N2O-双齿配体转变成N，N-双齿配体，配合物的发光又会如何？4、稀土配合物具有高的光致发光效率，但电致发光效率非常低，能否通过咔哇或呛二吟功能化来改善载流子传输，提高电致发光效率？主要工作及取得的结果概述如下：1、经由Knoevenagel缩合反应合成了一系列共骊的2，21-（1，4-芳二乙烯基）双-8-取代喹啉。单晶X-射线衍射研究表明固态下存在分子间，π…π堆积相互作用，这对于载流子传输是比较有利的。喹啉8-位于的取代基的变化对发光影响不大，表明刚性共扼骨架对发光起主要贡献。改变中心的芳核，明显可以调控发光颜色。当存在分子内电荷转移时，与不存在的相比，发光显著红移。电致发光性质表明这些含双喳琳的PPV齐聚物是良好的发光和电子传输材料。2、存在分子内氢键的化合物2-（2-羟基苯基）-5-苯基-1，3，4-噁二唑（HOXD），具有激发态分子内质子转移（ESIPT）特性。在室温下，用365脚的紫外灯照射时表现强的兰色荧光。室温和低温（77K）下的磷光光谱表明它在固态下具有较强的磷光发射，与理论预测完全一致。多层电致发光器件ITO加PB／HOXD／BCP／Alq3／Mg：Ag最大亮度达到656cd／m2，电流效率为0．37cd／A。当把HoxD掺在cBP中时，亮度和效率都有一定程度的提高，达到870cd／m2和0.82cd／A。3、合成了含有德二哩配体（HOXD）的碱金属配合物MOxD（M=Li，Na，K）。我们发现配合物的发光颜色取决于中心金属离子，LiOXD是一个优良的蓝光材料，半峰宽是65nm，发射峰位在478nm，它也可以作为界面材料使用，起到和LIF相同的作用，即改善电子注入。同时作者首次报道了钠和钾的配合物可以用作发光材料。电致发光性质表明这些配合物是优良的蓝／绿色发光和电子注入／传输材料。4、使用从N双齿配体代替N，O-双齿配体（比如8-羟基喹啉），合成了含有2－（2-羟基喹啉）苯并咪唑的锌、铍和硼配合物。用硼配合物作为发光层的三层器件ITO/NPB/boron-complex／Alq3／LiF／A1所得到的光谱覆盖了从400到750nm的区域，表明获得了一个很好的白色发光。白光分别源于激子和激基复合物发光，由三种成分构成：来自于硼配合物的兰色发光（490nm）；来自于Alq3的发光（535nln）；NPB和BPh2（Pybm）界面形成的激基复合物发光（610nm）。器件最大亮度是110cd／m2最大效率是0.8cd／A。5、设计、合成了咔唑、噁二唑功能化的稀土馆配合物，期望通过改善空穴和电子传输来提高发光效率。含咔哇的配合物的双层器件发光光谱较宽，包括三价铺的特征发射和一个宽峰，可能是咔唑的发光。当使用TPD做空穴传输层时，噁二唑铺配合物的电致发光器件得到纯正明亮的红色发光，器件结构为ITO／TPD（40nm）／（OXD-PyBM）Eu（DBM）3（SOnm）／LiF（Inm）／Al（200m），启动电压为7.8V，在21v时达到最大亮度322cd／m2。亮度为57cd／m2和13．sv时电流效率最大，为1.9cd／A，对应外量子效率是1.7％。高的效率表明通过引入噁二唑基团，配合物的电子传输能力得到明显改善。6、初步研究了三线态发光的铱的金属有机配合物，得到了高亮度、高效率的绿色发光；对8-羟基喹啉锌配合物的高分子化也做了初步探讨。

手性有机小分子路易斯碱催化剂的设计、合成及其在亚胺不对称还原中的应用

手性胺是合成天然产物和手性药物的重要中间体，亚胺的不对称催化还原是制备光学活性手性胺的最直接有效的方法之一。但是，由于C＝N双键的反应活性较弱以及容易发生E/Z异构等问题，亚胺的不对称催化还原具有很大的挑战性，既具有高对映选择性又具有宽广底物普适性的催化剂很少。 本文分别由手性脯氨酸、哌啶酸、哌嗪酸以及氨基醇出发，设计和合成了一系列结构新颖、合成简便、性能优良的酰胺类有机小分子路易斯碱催化剂，以廉价的三氯氢硅为氢源，用这些催化剂催化亚胺不对称还原，得到了非常优良的收率、对映选择性和前所未有的底物普适性。 文献研究认为，除N-甲酰基外，分子内含有芳香酰胺是能催化亚胺还原的有机小分子路易斯碱催化剂具有较高对映选择性的必要条件，我们研究发现N-甲酰脯氨酸非芳香酰胺类催化剂（包括结构简单的C2-对称型脯氨酰胺类催化剂），对N-芳基酮亚胺的还原可获得达86%的对映选择性，远高于同类芳香酰胺催化剂，证明N-甲酰非芳香酰胺类路易斯碱催化剂在亚胺还原中也能得到高的对映选择性。 在进一步研究中，我们以手性六元哌啶酸为模板，分别设计合成了N-甲酰哌啶酸芳香酰胺和N-甲酰哌啶酸非芳香酰胺两类催化剂，其中芳香酰胺催化剂（S）-N-（甲酰基）哌啶-2-酸-1-萘基酰胺（28）和非芳香酰胺催化剂（2S,1'S,2'S）-N-（甲酰基）-哌啶-2-酸（1',2'-二苯基-2'-乙酰氧基-乙基）酰胺（30）显示出非常优良的催化活性和对映选择性，对于N-芳基芳香酮亚胺的还原，无论是缺电子体系还是富电子体系，绝大部分都能得到很高的收率（达98%）和对映选择性（达96% ee)。特别值得一提的是30对一些脂肪族亚胺和α,β-不饱和亚胺的还原，虽然底物为E/Z混合物，也能得到很高的收率（达93%）和对映选择性（达95% ee)，这样的底物普适性在过渡金属催化体系中也是前所未有的。 现有的催化亚胺还原的高对映选择性催化体系大多仅适用于甲基酮亚胺底物，对位阻较大的非甲基酮亚胺很难获得好的结果。我们以L-哌嗪酸为模板设计和合成出的（S）-N-（甲酰基）-哌嗪-2-酸-4-对叔丁基苯磺酰基-苯基酰胺不但对N-芳基甲基酮亚胺有很好的对映选择性（达90% ee)，而且对于大位阻的N-芳基非甲基酮亚胺有更好的对映选择性（达97% ee)。该催化剂与30在底物普适性方面具有很好的互补性。 我们还设计了基于1,2-二苯基氨基醇为模板的新型N-甲酰路易斯碱有机小分子催化剂，首次发现结构简单的N-甲酰（1S,2R）二苯基氨基醇能较好的催化N-芳基酮亚胺，最高可以得到82%的对映选择性。 针对我们设计合成的结构新颖、性能优良的催化剂，我们对催化机理进行了探讨和解释，提出了几个假想的机理模型。 Catalytic enantioselective reduction of imines represents one of the most straightforward and efficient methods for the preparation of chiral amines, an important intermediate for the synthesis of natural products and chiral drugs. However, asymmetric reduction of imines remains a big challenge and highly enantioselective catalysts with a satisfactorily broad substrate scope remain elusive. Factors contributing to the difficulty of this transformation include the weak reactivity of the C=N bond and the existence of inseparable mixtures of E/Z isomers. Starting from chiral proline, pipecolinic acid, piperazine-2-carboxylic acid and 1,2-diphenyl amino alcohol, a series of structurally simple and easily prepared amides were developed as highly effective Lewis basic organocatalysts for the asymmetric reduction of imines with trichlorosilane as the reducing agent, which promoted the reduction of N-aryl imines with high yields and excellent enantioselectivities with an unprecedented substrate spectrum. In the literature, it has been believed that besides the N-formyl group, the existence of an arylamido group in the structure of Lewis basic organocatalysts is a prerequisite for obtaining high enantioselectivity in the catalytic reduction of imines. However, we found that the N-formyl-L-prolinamides bearing non-arylamido groups, including structurally simple C2-symmetric tetraamides, could also work as effective Lewis basic catalysts to promote the asymmetric reduction of ketimines with high enantioselectivities (up to 86% ee), which are even more enantioselective than the analogues with arylamido groups. In further studies, we developed novel N-formamides with arylamido groups and non-arylmido groups as Lewis basic catalysts using the commercially available L-pipecolinic acid as the template. The catalysts (S)-1-formyl-piperidine-2-carboxylic acid naphthylamide 28 and (2S,1'S,2'S)-acetic acid 2-[(1-formyl-piperidine-2-carbonyl) -amino]-1,2-diphenyl-ethyl ester 30 were found to promote the reduction of a broad range of N-aryl imines in high yields (up to 98%) and excellent ee values (up to 96%) under mild conditions. Furthermore, catalyst 30 also exhibited high enantioselectivities (up to 95% ee) for the challenging aliphatic ketimines and α,β-unsaturated imines despite that these imines exist as E/Z isomeric mixtures. The broad substrate spectrum of this catalyst is unprecedented in catalytic asymmetric imine reduction, including transition-metal-catalyzed hydrogenation processes. Many of the currently available highly enantioselective catalytic systems only tolerate methyl ketimines, which gave poor results for bulkier non-methyl ketimines. Starting from L-piperazine-2-carboxylic acid, we developed (S)-4-(4-tert- butylbenzenesulfonyl)-1-formyl-N-phenyl-piperazine-2-carboxamide as highly enantioselective Lewis basic catalysts for the hydrosilylation of both methyl ketimines and steric bulky non-methyl ketimines. Moreover, higher enantioselectivities were obtained for non-methyl ketimines than methyl ketimines under the catalysis of this catalyst. Thus, this catalyst system complements with 30 in terms of the substrate scope. We also found that easily accessible (1R,2S)-N-formyl-1,2-diphenyl- 2-aminoethanol worked as an effective Lewis basic catalyst in the enantioselective hydrosilylation of ketimines, affording high enantioselectivities (up to 82% ee) for a broad range of ketimines. To rationalize the high efficiencies of the structurally novel catalysts we developed, several catalytic models have been proposed.

吲哚生物碱Desbromoarborescidine A 的全合成及烯胺C-亚磺酰化反应研究

从新几内亚核桃木的树皮中分离得到的吲哚类喹诺里西定生物碱10-Desbromoarborescidine A，因发现其具有阻滞钙离子通道的活性而倍受关注。10-Desbromoarborescidine A由A、B、C、D四个环组成，只有一个手性中心，是吲哚生物碱中结构较简单的一种，常作为此类生物碱全合成方法的模型化合物。但迄今为止，能高效而简便的实现手性10-Desbromoarborescidine A不对称全合成方法线路不多，大多数以不对称诱导的方式建立其手性中心，手性催化的方式仅有一例金属催化。从逆合成分析可知，Desbromoarborescidine A的全合成可以通过亚胺不对称催化还原进行关键的手性中心构建，而本课题组在之前的研究中通过手性有机小分子催化剂的发展，已将三氯硅烷氢转移还原亚胺发展成了一类简便实用、高效、高对映选择性并具有优良底物适应范围的不对称催化反应，我们希望以这一反应作为关键手段，发展一条Desbromoarborescidine A及其类似物不对称合成新路线。 根据我们设计的新路线，首先成功合成了其关键中间体，然后我们进行了关键的不对称催化尝试。用本实验室已有的高性能有机小分子催化剂虽得到了较好的对应选择性，但是产率很低。同时，为了验证整条线路的可行性，我们也用消旋的中间体进行拉通线路的尝试。但不幸的是，在脱除保护基时遇到了很大困难。尝试换不同的保护基，或改变脱保护基的顺序，都未能成功合成目标产物。究其原因可能是由于吲哚的特殊性造成的，吲哚类亚胺与常规的芳香亚胺有较大的差异，其NH基团无论保护还是不保护，对与其2位相联接的C=N双键均有很大的影响，导致其不对称催化还原难以进行。另外，由于所设计的还原产物含有处在吲哚苄位的胺基，稳定性较差，造成保护基脱除困难。 烯胺C-亚磺酰化反应是本课题组最近发现的一个新反应，之前未见文献报道。本研究对该反应进行了反应条件优化和底物扩展，发现带Cbz，Ac，COt-Bu，CO2Et，Bz等保护基的一系列环状和非环状烯胺在亚磺酸钠、DMAc和MeSiCl3的共同作用下能高效高产率生成β-胺基烯基亚砜类新化合物，为合成多官能团化的烯基亚砜新化合物提供了一条简便实用的途径。 The main constituent of Dracontomelum mangiferum B1, indoloquinolizidine alkaloid 10-Desbromoarborescidine A, has drawn great attention due to its calcium channel blocking activity. Its molecular structure is relatively simple compared with the other alkaloids of the same type, which has only one chiral center, albeit with four cycles A, B, C, and D. This compound is often used as a model target for exploring different strategies for the total synthesis of indole alkaloids. Nevertheless, so far there still lack practical and highly efficient methods for the asymmetric total synthesis of 10-Desbromoarborescidine A. Most of the current available methods rely on stoichiometric asymmetric synthesis for the construction of the chiral center. There is only one example reporting utilization of asymmetric catalysis, but with transition metal complex as the catalyst. Our retrosynthetic analysis shows that catalytic asymmetric reduction of imine could be used as the key step for the construction of the chiral center of Desbromoarborescidine A. Since in the previous studies our group has developed the asymmetric reduction of imines by trichlorosilane into a practical and highly efficient and enantioselective method using newly designed chiral organocatalysts, we hope to apply this method to develop a novel synthetic route for the total synthesis of Desbromoarborescidine A and its analogues in this study. According to the newly designed synthetic route, we first accomplished the synthesis of the key intermediates which was then examined for the critical asymmetric catalysis. The asymmetric reduction using the highly efficient organocatalysts, developed in our lab afforded high ee but poor yield. We tried different reaction conditions to improve the yield, but failed to get any good results. Simultaneously, to vertify the feasibility of the synthetic route we designed, we also tired to go through the route toward the racemic synthesis of Desbromoarborescidine A. But unfortunately, protection and deprotection proved to be big hurdles. All the different protection groups and different sequences of protection and deprotection we tried failed to get us through the designed synthetic sequence and furnish the final product. Most likely, the indole part is the culprit behind the failures.The NH group of the indole, no matter protected or not, may impact the catalytic asymmetric reduction of C-N double bond connected with 2-C. Additionally, the reduction product we designed contains an amino group in the β-position of the indole, which may cause problems due to its instability. C-sulfenylation of enamines is a novel reaction discovered recently by our group, which has not been seen before in the literature. In this study, optimization of the reaction conditions and exploration of the substrate scope were further undertaken for this reaction, which reveal that a series of enamines with N-Cbz, Ac, COt-Bu, CO2Et protection groups could all undergo smooth C-sulfinylations with the comined use of sodium benzene sulphinate, DAMc and MeSiCl3, efficiently furnishing the β-amino vinylsulfoxide products in high yield, affording a practical and highly efficient methods for synthesis of functional vinylsulfoxides.

Evidence for perimeter sites over SmOx-modified Rh(100) surface by CO chemisorption

SmOx modified Rh(l 0 0) surfaces have been in-situ prepared by depositing metallic Sin and subsequently oxidizing under controlled conditions, and the interaction between the lanthanide oxide and transition metal has been characterized by means of X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy (HREELS) as well as thermal desorption spectroscopy (TDS). As evidenced, the adsorption of CO on the modified surfaces shows some different features to the original surface of Rh(l 00). The covering of SmOx blocks some sites on the surface and consequently suppresses adsorption of the typical CO species with an uptake at about 500 K, while a novel desorption peak centered at 260 K emerges in the CO TDS. Correspondingly, the XP spectrum exhibits a new C Is peak at 287.9 eV and 0 Is peak at 532.6 eV. The intensity of the low temperature peak varies with the coverage of SmOx, which shows an actual correlation to the perimeter sites of SmOx particles on the surface. (C) 2004 Elsevier B.V. All rights reserved.

Magnetic structure and orbital ordering in tetragonal and monoclinic KCrF3 from first-principles calculations

KCrF3 has been systematically investigated by using the full-potential linearized augmented plane wave plus local orbital method within the generalized gradient approximation and the local spin density approximation plus the on-site Coulomb repulsion approach. The total energies for ferromagnetic and three different antiferromagnetic configurations are calculated in the high-temperature tetragonal and low-temperature monoclinic phases, respectively.

Constructing channel structures based on the assembly of p-sulfonatocalix[4]arene nanocapsules and [M(bpdo)(3)](2+)(M = Cu, Zn)

Novel channel structures based on [M(bpdo)(3)](2+) and p-sulfonatocalix[4]arene nanocapsules have been established; these are sustained exclusively by charge-assisted pi...pi interactions and sorption experiments show the porous materials have selective guest sorption properties.

Efficient white organic light-emitting diodes using europium complex as the red unit

Efficient white organic light-emitting diodes (WOLEDs) using europium complex as the red unit are presented. The WOLEDs were fabricated by using the structure of indium tin oxide (ITO)/N, N'-di(naphthalene-1-yl)-N, N'-diphenyl-benzidine (NPB)/4,4-N, N-dicarbazolebiphenyl (CBP) : bis(2,4-diphenylquinolyl-N, C-2) iridium (acetylacetonate) ((PPQ)(2)Ir(acac)) : Eu (III) tris(thenoyltrifluoroacetone) 3,4,7,8-tetramethyl-1,10-phenanthroline (Eu(TTA)(3)(Tmphen))/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN) : p-bis (p-N, N-di-phenyl-aminostyryl)benzene (DSA-Ph)/9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminium (Alq3)/LiF/Al.