负载型过渡金属氧化物催化剂上SO2的还原

研究了γ-Al2O3负载过渡金属氧化物催化剂上CO还原SO2的反应,考察了系列过渡金属对该反应的催化活性,发现Fe系催化剂的性能最好。同时对还原反应的条件进行了选择,发现在较低温度下,大空速不利于SO2的还原,而在较高温度下,气体空速对反应影响不大,不同的物料配比对反应结果有很大影响,当CO：SO2=2时,最有利于单质硫生成。研究证明,金属硫化物是催化SO2还原反应的活性阳,该活性相的形成与催化剂的氧化还原能力有关,整个还原反应的机理应为中间产物机理。     

过渡金属硫化物催化剂上SO2的还原

 对系列过渡金属硫化物催化剂上CO还原SO2的反应进行了研究．结果表明，FeS的催化性能最好，而MnS的催化性能最差，其他几种催化剂的活性顺序依次为CoS＞CuS＞NiS．催化剂的活性与硫化物自身的氧化还原能力、所具有的晶相结构及其同SO2的吸附键合作用力有密切的关系．在硫化物催化剂上，SO2还原的反应机理很可能是贫、富含硫化合物的交替作用机理．     

含氧气氛下预硫化钙钛矿LaCoO3上的CO还原SO2反应

 对钙钛矿LaCoO3在含氧气氛下的预硫化过程进行了研究．结果表明，在一定含氧气氛下硫化后的LaCoO3催化剂，用于含氧气氛下CO还原SO2反应具有很高的活性．XRD物相分析结果表明，硫化后的LaCoO3仍保持钙钛矿物相结构，但同时出现新的硫化物La2O2S和氧化物Co3O4物相．通过对硫化前后的催化剂进行O2－TPD和SO2－TPD分析，认为CO还原SO2反应机理可能是在一定的温度下，在钙钛矿LaCoO3上发生CO氧化燃烧反应，在硫化物La2O2S上发生CO还原SO2反应，两者相互促进．     

稀土氧化物上SO2和NO的催化还原Ⅱ.用CO作还原剂的脱硫及反应机理

采用连续流动固定床石英反应器,在反应气体为1%SO2和2%CO, 流量为180 ml/min, 以及催化剂用量为0.5 g的条件下,考察了经活化处理的稀土系列氧化物对CO还原SO2的催化活性,探讨了空速、温度和水蒸气等因素对反应的影响.所研究的样品依据对SO2的转化能力可分为三组: 高活性的镧、镨、钕、钐、铕和钆氧化物; 低活性的铈、钬和铒氧化物; 无活性的铽和镝氧化物.在活性最高的钕和钐氧化物样品上, 450 ℃时SO2的转化率＞98%.反应过程中,活性相为稀土氧硫化物,反应遵从COS中间物机理.     

浸渍沉淀法制备活性炭负载Co-Mo双金属脱硫催化剂

以氧化改性活性炭为载体,尿素为沉淀剂,采用浸渍沉淀法制备了负载型Co-Mo催化剂,并用CO还原SO₂反应作为模型反应考察了催化剂的催化活性。结果表明,催化剂焙烧温度500℃、Co/Mo物质的量比0.45、最佳反应条件(硫化温度为500℃、空速为7 000 mL/(g·h)、CO/SO₂物质的量比为2:1,反应温度为450℃)时,催化剂具有最好的催化活性和选择性。XRD表征结果表明,催化CO还原SO₂反应的活性相为CoS₂和MoS₂,硫化温度影响活性相的形成。该催化剂稳定性好,反应运行24 h后活性仍能保持最高活性的99%。     

水汽-CO_2环境下Pt/CeZrO_2催化剂的CO氧化性能研究

采用浸渍法制备了Pt/Ce0.6Zr0.4O_2粉末催化剂,涂覆到蜂窝陶瓷载体表面得到整体式催化剂。考察了Pt含量及焙烧温度对催化剂在水汽-CO_2环境下催化CO氧化性能的影响,并用XRD,TEM和H2-TPR等手段对载体和催化剂进行了表征。结果表明,在空速50000 h-1的反应条件下,当焙烧温度为300℃时,3.0Pt/Ce0.6Zr0.4O_2整体式催化剂的CO氧化活性最高,反应温度200℃时,CO转化率为87%,具有较高的水汽-CO_2环境下的CO氧化活性。通过对2.0Pt/Ce0.6Zr0.4O_2催化剂在无水汽,无CO_2,无水汽-CO_2及水汽-CO_2环境下的对比实验,发现水汽和CO_2对催化剂的活性有明显的抑制作用,水汽的影响比CO_2的影响要更大一些。这说明水汽、CO_2和CO对催化剂存在竞争吸附。结合催化剂的H2-TPR表征结果,发现催化剂的还原能力越高,相对应的CO氧化活性也越高。添加适量的Pt有利于提高催化剂的还原能力,从而提高其活性,但是过量的Pt会使催化剂活性下降。     

新型CeO2/HBEA催化剂上NH3低温还原NO活性及抗毒性能研究

采用等体积浸渍法制备了CeO2/HBEA催化剂,用于NH3选择性催化还原NO.考察了CeO2负载量、焙烧温度、氧浓度、空速、以及SO2和水蒸气等因素对催化剂活性的影响,并运用BET、X射线衍射(XRD)、扫描电镜(SEM)、热重分析(TGA)、傅里叶红外(FTIR)等手段对该催化剂进行表征,研究了催化剂的晶相、微观形貌与抗毒机制.结果显示:CeO2/HBEA催化剂具有良好的脱硝活性,高活性温度窗口在220～400℃,当反应温度为220℃、空速为12 000 h-1时,NO的转化率达96.49%.H2O的存在对催化剂的脱硝活性无明显影响.SO2一定程度抑制该催化剂的低温脱硝活性,但随着温度的升高,其脱硝活性得到一定恢复.所制备的CeO2/HBEA催化剂有良好的低温活性,能适应较高的空速,且具有较强的抗硫性和抗水中毒性能,有一定的应用前景.     

Ni_2P催化剂的低温还原法合成及其HDS性能

在低还原温度下程序升温还原法制备了Ni2P/MCM-41催化剂,并采用H2-TPR、TG-DTG、XRD、BET、XPS等手段对制备的催化剂进行了表征,考察了还原温度对活性相Ni2P形成以及催化剂二苯并噻吩HDS性能的影响。结果表明,在210~390℃下还原得到的催化剂活性相为单一的Ni2P相;在390℃下还原得到的催化剂具有最高的二苯并噻吩HDS活性,在反应温度340℃、反应压力3.0 MPa、氢/油体积比500、质量空速(WHSV)2.0 h-1的条件下二苯并噻吩HDS转化率达到99.0%。     

CO为还原剂同时还原SO2和NO的SnO2-TiO2固溶体催化剂Ⅰ.催化剂的催化性能

 采用共沉淀法制备了不同SnO2含量的SnO2-TiO2固溶体催化剂. 发现该催化剂对以CO为还原剂同时还原SO2和NO生成S和N2的反应具有高活性和高稳定性. SnO2含量为50%(摩尔分数)的样品活性最高,在350 ℃, 0.0525% SO2, 0.052% NO, 0.208% CO和空速3000 h-1的条件下,NO转化率接近100%, SO2转化率为88%, S和N2的选择性都接近100%,反应过程中没有剧毒气体COS生成. 对于SO2+CO反应,该样品也显示了极高的活性,在350 ℃, 0.105% SO2, 0.208% CO和空速3000 h-1的条件下,SO2转化率达98%, S的选择性近100%. 但该催化剂对NO+CO反应的催化活性不高,在350 ℃, 0.1025% NO, 0.208% CO,空速3000 h-1的条件下, NO的转化率仅为50%. 上述结果表明, SO2对NO+CO反应具有促进作用. 单独的SnO2或TiO2对SO2+CO, NO+CO或SO2+NO+CO反应的催化活性都很低,但SnO2和TiO2形成SnO2-TiO2固溶体后催化活性显著增大,说明SnO2和TiO2之间产生了协同效应.     

稀土-铁催化剂催化还原烟气中SO2制硫磺

以煤气为还原气,以Fe为主活性金属,稀土为助剂催化还原冶炼烟气中SO2制取硫磺,研究了不同稀土、不同稀土含量及不同催化剂制备方式对稀土-过渡金属催化剂催化还原SO2制硫磺活性的影响,并考察了其反应机制.结果表明:不同稀土对Fe/Al2O3催化剂有不同的改性作用,Sm和Dy的加人大大提高了催化剂的活性,在360 ℃时,smFe/Al2O3的硫产率增大到86.62%,比同温度下Fe/Al2O3的提高了40.5%;在400℃时,DyFe/Al2O3的硫产率增大到91.62%.比同温度下Fe/Al2O3的提高了26.4%;REFe/Al2O3催化剂的活性与稀土含量有一定的关系,对SmFe/Al2O3催化剂,稀土Sm的最佳含量为1.0%;不同方式制备的稀土催化剂活性不同,对硫产率来说其大小顺序为:钐铁溶液混浸>先浸钐后浸铁>先浸铁后浸钐;煤气还原SO2的反应机制为中间产物机制.     

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.     

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.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Cu0-catalysed 1,3-dipolar cycloadditions of α-amino acid derived N,N-cyclic azomethine imines to ynones

A series of 20 CuAIAC reactions between eight 4-acylamino substituted pyrazolidine-3-one-1-azomethine imines and four terminal ynones were performed using Cu⁰ as catalyst. The corresponding fluorescent cycloadducts were obtained in very high yields upon simple workup. Thus, Cu-metal turned out to be a better catalyst than Cu^I in terms of yield and ease of isolation. Availability of azomethine imines, mild reaction conditions, and simple workup enable a “click” access to libraries of densely substituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazol-1-ones. Reactivity of differently substituted dipoles was evaluated experimentally and by quantum chemical methods (DFT).     

Synthesis and antioxidative/anti-inflammatory activity of novel fullerene–polyamine conjugates

(E)-4-(Fullerenopyrrolidin-1-yl)-3-methylbut-2-enoic acid and its corresponding succinimidyl ester, readily obtained through Prato-type modification of C₆₀, were used for the selective N-acylation of polyamines. The thus obtained conjugates were evaluated for their antioxidative and anti-inflammatory activity and their cytotoxicity was determined. Members of this family of compounds showed interesting anti-lipid peroxidation, anti-lipoxygenase and anti-inflammatory activity and comparable cytocompatibility to spermidine.