介孔氧化铝负载钒催化剂上丙烷氧化脱氢制丙烯

 采用浸渍法制备了介孔氧化铝 (m-Al2O3) 负载钒催化剂 (V/m-Al2O3), 并考察了其催化丙烷氧化脱氢制丙烯反应活性. 通过 N2 吸附-脱附、透射电镜、X 射线粉末衍射、紫外-可见漫反射光谱、氢-程序升温还原和氨-程序升温脱附对催化剂进行了表征. 结果表明, 介孔氧化铝具有大比表面积、窄孔径分布和两维六方相结构, 在其上负载适量的 V 可实现 V 活性物种的高分散及催化剂的弱酸性, 从而有利于提高丙烷转化率和丙烯选择性. 与共合成法制备的含 V 介孔氧化铝 V/m-Al2O3(C) 和浸渍法制备的 V/?-Al2O3 相比, V/m-Al2O3 表现出更高的催化活性. 这与载体较弱的酸性和较大的比表面积以及 V 物种的高分散有关.     

Y2O3和Nd2O3介孔薄膜的制备与表征

以聚乙烯合丁烯-嵌-聚氧乙烯嵌段共聚物(PHB-PEO)作模板, 采用蒸发诱导自组装方法, 分别制备了Y2O3和Nd2O3介孔薄膜. 用小角、广角X射线衍射和透射电子显微镜对薄膜样品在不同的热处理阶段进行了表征. 结果表明, 所制备的Y2O3和Nd2O3薄膜样品呈现一种大孔径(平均孔径分别约为11.5和12.5 nm)、有序的立方扭曲球形孔排列、稳定于450 ℃并具有部分晶态孔壁结构的介孔薄膜材料.     

H_3PW_(12)O_(40)掺杂TiO_2介孔材料的制备及光催化性能

以P123为模板剂,采用溶胶-凝胶的溶剂热合成方法制备了H3PW12O40掺杂TiO2介孔材料H3PW12O40/TiO2.利用紫外可见漫反射吸收光谱(UV-vis/DRS)、X射线粉末衍射(XRD)、N2吸附和透射电子显微镜(TEM)手段对所制备的材料进行结构表征,罗丹明B(RB)为模型污染物评价其光催化性能.结果表明,所制备的介孔材料具有锐钛矿与板钛矿复合的晶型结构、大的BET比表面积和孔径均匀分布的介孔结构.光催化实验表明,H3PW12O40/TiO2可将罗丹明B完全矿化.     

孔径可控的介孔TiO2纳米球的溶剂热合成

以具有微孔结构的乙二醇钛(TG)为前驱体, 采用无模板法制备了一系列单分散的介孔TiO2纳米球. 通过溶剂热处理, 微孔前驱体TG原位水解直接转化为具有介孔结构的TiO2纳米球. 通过X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FTIR)及氮气吸附-脱附等对产物进行了表征. 测试结果表明, 产物具有高结晶性、均一的形貌、可调的孔径和比表面积.     

银掺杂介孔氧化铝抗菌剂的一步合成与表征

以Al(NO_3)_3·9H_2O和AgNO_3为原料,采用水热法制备了介孔氧化铝纳米粒子(Mesoporous Al_2O_3NPs)和银掺杂介孔氧化铝纳米粒子(Mesoporous Ag/Al_2O_3NPs),通过X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、X射线荧光光谱(XRF)、能量分散X射线衍射(EDX)和低温N2吸附-脱附等手段对产物进行了表征,通过最低抑菌浓度和抑菌圈实验研究了材料的抗菌性能.XRD分析表明在介孔Ag/Al_2O_3NPs中Al_2O_3是唯一结晶相,Ag掺杂后,介孔Ag/Al_2O_3NPs晶格常数和半高峰宽增大,晶面间距[(111),(400)和(440)面]减小.FE-SEM形貌分析表明掺杂后的介孔Ag/Al_2O_3NPs颗粒直径减小而孔径增大.EDX和XRF分析表明介孔Ag/Al_2O_3NPs中O/Al摩尔比为1.5,与Al_2O_3NPs中O/Al摩尔比相同.综合XRD和XRF分析结果认为,Ag进入介孔Al_2O_3晶格间隙形成间隙固溶体.低温N2吸附-脱附分析表明掺杂后的介孔Ag/Al_2O_3NPs比表面积、孔体积和孔径增大.曝气抗菌实验结果表明介孔Ag/Al_2O_3NPs的抗菌机理是活性氧和金属银的协同作用.介孔Ag/Al_2O_3NPs对革兰氏阴性菌(大肠杆菌)和革兰氏阳性菌(金黄色葡萄球菌)具有明显的抗菌效果,对大肠杆菌和金黄色葡萄球菌的最低抑菌浓度(MIC)均为80μg/m L,抑菌圈直径分别为26 mm和24 mm.     

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Cu2+,Pb2+,Zn2+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Al2O3:RE3+的制备及Gd3+对Eu3+的能量传递

以P123为表面活性剂,异丙醇铝为铝源,用简易溶胶-凝胶法,获得了单掺和双掺Gd3+,Eu3+的介孔氧化铝组装体.用广角X-射线衍射仪(WAXD)进行了物相分析;小角X-射线衍射仪(SAXD)、比表面仪进行了孔结构分析和形貌表征;研究了组装体的发光性能并发现Gd3+对Eu3+有能量传递作用,并分析了能量传递过程.     

双模板法合成介孔/大孔二级孔道碳材料

以酚醛树脂低聚物为前驱物, 利用双模板法制备了具有介孔/大孔双孔结构的碳材料. 其中以二氧化硅蛋白石为大孔模板, 以嵌段共聚物自组装结构为介孔模板. 对样品进行了扫描电子显微镜(SEM), 透射电子显微镜(TEM), X射线衍射(XRD)和氮气吸附-脱附实验表征. 结果表明所制备的双孔碳材料大孔直径约为230 nm, 介孔直径10 nm.     

氧化钨介孔材料的制备与表征

以介孔二氧化硅(KIT-6)为硬模板, 硅钨酸为钨源, 用硬模板法制备WO3-SiO2复合材料, 再利用HF除去二氧化硅, 得到了介孔三氧化钨材料. 用X射线衍射(XRD)、能量扩散X射线(EDX)、高分辨透射电镜(HRTEM)、N2吸附-脱附等表征手段, 对制备复合材料的物料比、煅烧温度以及不同分散剂等条件进行了考察. 结果表明, 硅钨酸与硅介孔的物料比(m(WO3)/m(SiO2))在3:1到4:1之间, 在600-750 ℃下煅烧, 能制备结构较好的介孔氧化钨. 乙醇和蒸馏水为分散剂时, 用乙醇为分散剂所得的介孔WO3材料具有更高的比表面积和孔体积.     

Y2O2S∶Eu3+空心微球的制备与性能

以单分散的碳球为硬模板,采用均匀共沉淀法合成了Y2O2S:Eu3+心微球.通过XRD、SEM、TEM、荧光光谱对其进行表征.X射线衍射测试表明所制备的Y2O2S:Eu3+空心微球为单相,六方晶.扫描电子显微镜(SEM)和透射电子显微镜(TEM)测试表明所制备的Y2O2S:Eu3+空心微球粒径小,分布均匀.激发和发射光谱测试表明Eu3+离子能有效地掺入硫氧化钇基质中,并具有良好的发光性能.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.