微波助离子液体中TiO_2/聚苯乙烯复合材料的制备与光催化性能研究

以钛酸丁酯为前驱物,在离子液体([Bmim]BF4)中采用微波辐射加热法合成了TiO2/聚苯乙烯(PS)复合材料,用TG、XRD、IR、XPS和SEM对复合材料进行了表征.通过测试复合材料在乙酸乙酯中的吸光度及对甲基橙溶液的降解率,考察了离子液体体积、微波功率、反应温度、反应时间等因素对复合材料分散性和光催化活性的影响.结果表明:微波助离子液体介质中制备TiO2/PS复合材料的最佳条件是:钛酸丁酯与ST体积比为3.4∶1.1,[Bmim]BF42.0mL,微波功率700W,反应温度50℃,反应时间60min;在离子液体介质中使用微波辐射加热制备TiO2/PS复合材料,能够降低反应的温度,极大地缩短反应的时间;且制得的复合材料的亲油性能大大提高,在乙酸乙酯中具有较好的分散性,该复合材料不需要高温煅烧就具有较高的光催化活性(紫外光照射1.5h甲基橙降解率为96.2%).     

离子液体介质中微波辅助制备铁掺杂纳米TiO_2及光催化活性

在1-丁基-3-甲基咪唑六氟磷酸盐([Bmim]PF6)离子液体中,用微波干燥的方法制备了铁掺杂的纳米TiO2-Fe光催化剂,并以甲基橙为模拟污染物,紫外灯为光源,考察了离子液体加入量、铁掺杂量、微波干燥功率、微波干燥时间、煅烧温度、煅烧时间等因素对TiO2-Fe光催化活性的影响.结果表明:在离子液体加入量为5.6 mL,掺杂物质硝酸铁与钛酸丁酯的物质的量百分比为0.005%,于家用微波炉中在210 W功率下干燥17.5 min,再在高温箱式电阻炉中于540℃煅烧处理1.5 h后所制得的TiO2-Fe光催化剂,分别用紫外光照90 min及太阳光照射3 h后,甲基橙都几乎达到完全降解,其活性明显优于未掺杂纯TiO2的光催化活性.     

微波超声强化银掺杂TiO_2催化剂光催化活性的研究

在[Bmim]PF6离子液体介质中,用溶胶凝胶-微波干燥法制备银掺杂TiO_2光催化剂TiO_2-Ag.以甲基橙为有机污染物,用微波超声组合仪分别在微波(MW)、紫外(UV)、紫外-微波(UV-MW)和超声-紫外-微波(UT-UV-MW)4种条件下降解甲基橙溶液,考察银掺杂对催化剂降解甲基橙的影响,以提高催化剂光催化性能.分别用X射线衍射分析(XRD)、扫描电子显微镜(SEM)、能谱分析(EDS)、热重-差示扫描量热分析(TG-DSCDTG)、固体紫外可见分析(Uv-vis)和红外分析(IR)对TiO_2-Ag催化剂进行测试表征.结果表明,优化条件下制备TiO_2-Ag催化剂在UV、UV-MW和UT-UV-MW条件下降解甲基橙35 min后,甲基橙的降解率分别为88.05%、93.98%和99.84%;降解甲基橙55min后,甲基橙的降解率分别为98.79%、99.05%和99.90%.在UTUV-MW条件下降解25min后,降解率接近100%.表明TiO2-Ag催化剂具有较高的光催化降解活性,微波超声协同作用加快光催化降解反应进行.催化剂的结构分析表明,银掺杂抑制了二氧化钛晶相的转变,使相变温度升高,稳定性增强;同时,催化剂向可见光区扩宽了光响应范围,提高了量子效率,从而光催化性能得以提高.     

微波助离子液体中锌和氮共掺杂TiO2催化剂的制备及微波强化光催化氧化活性

在1-丁基-3-甲基咪唑六氟磷酸盐（[Bmim]PF6）离子液体介质中,采用微波干燥的方法制备了锌和氮共掺杂的TiO2催化剂TiO2-Zn-N,分别采用IR、XRD、SEM、BET对催化剂结构进行了测试和表征。室温条件下,以甲基橙和苯酚溶液为模拟污染物,在微波超声波组合催化合成仪中,分别利用微波辐射（MW）、紫外光照（UV）、微波辐射-紫外光照（MW-UV）和太阳光照射（SL）等降解方式,着重考察了制备条件对TiO2-Zn-N光催化活性的影响。结果表明,在离子液体用量为5.6 mL、Zn掺杂量n(Zn)/n(Ti)=0.015:1、N掺杂量n(N)/n(Ti)=4:1、微波干燥功率350 W、微波干燥时间20 min、煅烧温度700 ℃、煅烧时间2 h的条件下所制得的TiO2-Zn-N催化剂具有较高的光催化活性;在MW、UV、MW-UV和SL四种降解条件下,TiO2-Zn-N对甲基橙的降解率分别为29.6%、95.4%、99.2%和79.2%;并且在前三种降解条件下,甲基橙降解率始终是：MW-UV> UV> MW。这表明在紫外光照条件下,微波辅射具有强化催化剂降解甲基橙的作用。     

纳米复合材料Ag/TiO_2-ZrO_2的制备及其微波增强光催化降解甲基橙

采用EO20PO70EO20(P123)作模板剂,通过溶胶-凝胶-程序升温溶剂热一步法,并经萃取处理制备了具有光催化活性的纳米复合材料Ag/TiO2-ZrO2.用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、N2吸附-脱附测定和扫描电子显微镜配合X射线能量色谱仪(SEM-EDS)等测试手段对其组成、结构及形貌等进行了表征.结果表明,复合材料Ag/TiO2-ZrO2中Ag以单质形式存在,材料具有双孔结构,颗粒分布较均匀,结构也较规整,平均孔径约为3.6和9.0nm.通过微波增强光催化降解染料甲基橙的实验,对复合材料Ag/TiO2-ZrO2的光催化活性进行了探究.实验结果表明,微波辅助光催化效果优于紫外辐射,并且萃取后的合成产物Ag/TiO2-ZrO2在90min内对甲基橙的降解率可达81.5%,其活性高于市售P25以及TiO2-ZrO2.     

微波助离子液体中Y掺杂TiO_2光催化剂制备及微波强化光催化活性

在微波助离子液体介质中制备稀土元素Y掺杂改性TiO_2光催化剂,以提高催化剂的光催化降解活性,用XRD、SEM和BET等测试手段对催化剂结构进行表征;以甲基橙溶液和苯酚溶液为模拟污染物,分别在紫外光照(UV)和微波辐射-紫外光照(MW-UV)条件下考察TiO_2-Y催化剂的光催化活性;以对苯二甲酸作为荧光探针利用荧光技术检测TiO_2-Y催化剂表面所产生的羟基自由基,并对光催化降解反应进行动力学分析,探索了光催化降解反应机理.实验结果表明,通过优化反应条件后制得的TiO_2-Y催化剂具有较高光催化活性和热稳定性,在UV和UV-MW条件下降解甲基橙和苯酚溶液1.5h后,甲基橙降解率分别为98.3%和99.5%,苯酚降解率分别为97.5%和98.2%.荧光光谱分析表明,TiO_2-Y在MW-UV条件下产生的羟基自由基比UV条件下要多,因而微波辐照具有强化TiO_2-Y降解模拟污染物的作用;反应动力学数据分析表明,TiO_2-Y光催化降解甲基橙溶液反应呈现一级反应动力学规律,其表观速率常数K最大值为0.051 9min-1.     

层状纳米光催化复合材料H0.8Fe0.8Ti1.2O4/TiO2的合成及性质

用固相合成法制备出K0.8Fe0.8Ti1.2O4,并用离子交换反应制备出H0.8Fe0.8Ti1.2O4;通过C3H7NH2层间膨胀,TiO2粒子的插入和紫外光分解等反应,合成出一种新的层状光催化纳米复合材料-H0.8Fe0.8Ti1.2O4/TiO2.X射线衍射和漫反射等表征结果表明 该样品的层间高度为0.47nm,禁带能隙为2.18和2.88eV.用(>400 nm的光照射30 min,0.4 g样品可使甲基橙溶液(20 mg/L)的降解率达到22.1%.而同样条件下标准TiO2(P-25)仅为6.2%,表明所研制的层状纳米复合材料具有较高的光催化活性.     

微波辅助离子液体中锌-铁共掺杂纳米TiO_2光催化剂的制备及其光催化活性

在[Bmim]PF_6离子液体介质中,用微波于燥的方法制备了锌-铁共掺杂纳米TiO_2(TiO_2-Zn-Fe)光催化剂;并以甲基橙为模拟污染物,紫外灯为光源,考察了离子液体加入量、锌-铁掺杂量、微波干燥功率、微波干燥时间、煅烧温度、煅烧时间等因素对TiO_2-Zn-Fe光催化活性的影响.结果表明,掺杂物质硝酸锌和硝酸铁与钛酸丁酯的物质的量比分别为n(Zn)/n(Ti)=0.25%和n(Fe)/n(Ti)=0.005%时,在家用微波炉中于210W功率下干燥17.5min,再在高温箱式电阻炉中于540℃下煅烧处理1.5h,得到的TiO_2-Zn-Fe光催化剂的活性明显优于单一掺杂的TiO_2-Zn或TiO_2-Fe以及未掺杂的纯TiO_2,在紫外光照60min及太阳光照3h条件下相应的甲基橙的降解率分别达99.8%和99.6%.     

碳纳米管/TiO_2复合材料的制备及表征研究

采用溶胶-凝胶法和水热合成法,制备出碳纳米管/TiO2(CNTs/TiO2)复合材料。通过X-射线衍射仪(XRD)、扫描电子显微镜(SEM),紫外-可见漫反射光谱(UV-Vis),荧光光谱(LS)检测CNTs/TiO2的晶型及形貌。结果表明:锐钛矿相TiO2纳米颗粒负载在碳纳米管的管壁上,CNTs/TiO2在紫外-可见光波长范围均有较好的吸收性能。在灭菌灯照射下,以甲基橙溶液为降解目标,CNTs/TiO2复合材料对甲基橙溶液的降解有高的光催化活性,180 min内降解率达到85%以上。     

纳米复合材料CdS/TiO_2制备与不同模式光催化降解多种染料

采用化学水浴沉淀法再结合溶胶-凝胶和程序升温溶剂热两步法制备了一系列不同比例的CdS/TiO2纳米复合材料。通过X-射线衍射(XRD)、X-射线光电子能谱(XPS)、扫描电镜(SEM)、紫外-可见漫反射吸收光谱(UV-Vis/DRS)和氮气吸附-脱附测试等手段对所合成纳米复合材料的组成、结构和形貌进行了表征。结果表明,该系列CdS/TiO2纳米复合材料为锐钛矿TiO2和六方相CdS的混合晶相,其对可见光有较强吸收,并且随着复合材料中TiO2比例的增加,BET值明显增大。另外,所合成的CdS/TiO2复合材料呈圆球形,颗粒比较均匀。紫外光催化降解甲基橙的实验结果表明,摩尔比为1∶4的CdS/TiO2复合材料的活性明显高于CdS、P25以及其他不同比例的CdS/TiO2。同时,1∶4 CdS/TiO2纳米复合材料在紫外光、可见光和微波辅助光催化等不同模式下对多种结构的染料均有较好的降解效果。     

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%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.