水-丁醇两相介质合成SAPO-11和MgAPO-11分子筛

在水-丁醇两相介质中合成了SAPO-11和MgAPO-11分子筛.水-丁醇两相介质有利于在SAPO-11中引入更多的Si,从而产生较多的酸性位,以所得SAPO-11为载体的Pt催化剂在正十二烷临氢异构化反应中表现出较高的催化活性.相反,水-丁醇两相介质不利于Mg进入分子筛骨架,导致MgAPO-11上的酸性位减少,Pt/MgAPO-11催化剂的催化活性降低.     

溶剂热法合成用于正十二烷异构化的高活性富硅Pt/SAPO-11催化剂

 采用溶剂热法,利用不同的硅源和铝源合成了富硅的SAPO-11分子筛. 结果显示,与水热法合成的样品相比,溶剂热法合成的Pt/SAPO-11催化剂具有较大的外表面积,同时其硅含量、酸度和对正十二烷异构化的催化活性均显著提高. 在所有合成的Pt/SAPO-11催化剂样品中,以正硅酸乙酯与异丙醇铝为原料,采用溶剂热法合成的催化剂具有最高的酸度与正十二烷异构化活性.     

溶剂热法合成用于正十二烷异构化的高活性富蛙Pt/SAPO-11催化剂

采用溶剂热法,利用不同的硅源和铝源合成了富硅的SAPO-11分子筛. 结果显示,与水热法合成的样品相比,溶剂热法合成的Pt/SAPO-11催化剂具有较大的外表面积,同时其硅含量、酸度和对正十二烷异构化的催化活性均显著提高. 在所有合成的Pt/SAPO-11催化剂样品中,以正硅酸乙酯与异丙醇铝为原料,采用溶剂热法合成的催化剂具有最高的酸度与正十二烷异构化活性.     

乙醇对Pt/SAPO-11和Pt/ZSM-22催化剂烷烃异构化性能的影响

选用SAPO-11、ZSM-22两种分子筛为载体,浸渍Pt制备了Pt/SAPO-11和Pt/ZSM-22催化剂,以正庚烷为模型化合物,考察乙醇对催化剂临氢异构化反应性能的影响。并通过BET、XRD、C₂H₅OH-TPD和C₂H₅OH-FTIR等表征手段对催化剂的物化性能以及吸附反应性能和不同活性酸性位点进行了研究考察。结果表明,乙醇在临氢异构转化过程优先生成H₂O,并以H₂O的形式影响催化剂的异构化性能,催化剂异构活性与选择性随乙醇含量的增加而降低。与Pt/ZSM-22催化剂相比,Pt/SAPO-11催化剂由于有P-OH基团,表现出一定的抗含氧化物乙醇的性能。     

乙醇对Pt/SAPO-11和Pt/ZSM-22催化剂烷烃异构化性能的影响

选用SAPO-11、ZSM-22两种分子筛为载体,浸渍Pt制备了Pt/SAPO-11和Pt/ZSM-22催化剂,以正庚烷为模型化合物,考察乙醇对催化剂临氢异构化反应性能的影响。并通过BET、XRD、C2H5OH-TPD和C2H5OH-FTIR等表征手段对催化剂的物化性能以及吸附反应性能和不同活性酸性位点进行了研究考察。结果表明,乙醇在临氢异构转化过程优先生成H2O,并以H2O的形式影响催化剂的异构化性能,催化剂异构活性与选择性随乙醇含量的增加而降低。与Pt/ZSM-22催化剂相比,Pt/SAPO-11催化剂由于有P-OH基团,表现出一定的抗含氧化物乙醇的性能。     

SAPO-11的制备及正十八烷异构性能研究

采用水热法合成出不同硅铝比的SAPO-11分子筛,负载Pt后在固定床反应器上对正十八烷进行临氢异构化.采用XRD、BET、SEM、TEM和NH_3-TPD对分子筛及催化剂进行表征.考察了不同Si含量对正十八烷临氢异构性能的影响,确定硅铝比为0.3最适宜;改变反应温度、压力、空速以及氢油比等参数,考察了0.5%Pt/SAPO-11催化剂的异构化性能.结果表明:340℃、3 MPa、空速为1 h-1和氢油体积比为1 000∶1时,正十八烷转化率达到73.1%,煤汽油比1.44,异构收率64.2%.     

不同链长正构烷烃在Pt/SAPO-11催化剂上的临氢转化规律研究

采用SAPO-11分子筛制备的双功能催化剂,以碳链长度为10-14的正构烷烃为模型化合物,探索了不同碳数的长链正构烷烃临氢转化反应规律。结果表明,低温下不同碳数的正构烃都表现出较高的异构化选择性,改变反应温度使反应转化率控制在85%以下时,正构烷烃的异构化选择性可以达到90%左右;随着碳数和温度升高,正构烷烃由于发生明显的裂化反应导致转化率提高和异构化选择性降低。采用SAPO-11分子筛催化材料的双功能催化剂具有明显的产物择形异构效应,异构化产物以甲基位于端位和碳链中心的单侧链异构体为主,双(多)支链产物较少。长链正构烷烃在Pt/SAPO-11催化剂上的裂化反应在低转化率以加氢裂化为主,裂化产物的碳数呈均匀分布;在高转化率下以酸催化裂化为主,裂化产物的碳数分布呈现明显的不对称分布特征。     

Zn改性的Pt/SAPO-11催化剂及其提高二甲基烷烃选择性（英文）

随着环保法规的日益苛刻,世界各国对发动机燃料指标的要求也越来越严格,汽油组分中的烯烃含量逐渐被限制.作为提高汽油辛烷值的有效手段,正构烷烃的临氢异构化越来越引起人们的重视.烷烃碳数相同时,具有多支链的异构体往往具有更高的辛烷值.因此,在正构烷烃临氢异构化过程中,提高多支链异构体的选择性具有重要意义.Pt/SAPO-11作为双功能催化剂具有适宜的孔结构、温和的酸性和适度的加氢脱氢活性,在烷烃临氢异构化反应中表现出色,得到了广泛研究.已有文献报道中,通过添加第二金属改性可以调节双功能催化剂的物理化学性质,进而影响其催化活性和产物选择性.为了提高异构产物选择性,特别是多支链异构产物的选择性,本文研究了Zn改性的Pt/SAPO-11催化剂在正辛烷临氢异构化中的反应性能,与未改性的Pt/SAPO-11催化剂相比,Zn改性的Pt/SAPO-11催化剂表现出更高的二甲基烷烃选择性.通过动态合成方法合成SAPO-11分子筛,进而制备Zn改性的Pt/SAPO-11催化剂.XRD表征表明,Pt和Zn的引入基本没有引起SAPO-11特征峰改变,并且未发现Pt和Zn氧化物的特征峰,说明金属组分得到很好的分散.氮气吸附-脱附实验表明,随着Zn添加量的增加,载体的比表面积和孔体积略有减少.NH_3-TPD和吡啶红外光谱用于表征Zn的加入对催化剂酸性的影响,结果表明,少量Zn的添加可以增加酸量,这是由于Zn的引入可以产生L酸性位;而随着Zn的增加,总酸量减少,这是由于过多的Zn覆盖了载体的酸性位.H_2-TPR和H_2-TPD表征发现,Zn的引入使得Pt在高温处的还原峰减小,说明Zn改变了Pt在载体上的位置,使其主要负载在分子筛外表面.由于Zn~(2+)是阳离子并具有较小的离子半径,它可以作为竞争吸附剂,首先进入分子筛孔道从而抑制了Pt进入分子筛孔道.H_2-TPD表明,Zn的引入使得H_2的脱附温度逐渐降低,这与Zn增加了Pt的分散度有关;但是当Zn的添加量达到0.7%时,H_2的脱附温度升高,同时溢流氢增加.以正辛烷为模型化合物,在固定床高压微型反应装置中对一系列催化剂进行了评价,考察了Zn改性的Pt/SAPO-11催化剂和未改性的Pt/SAPO-11催化剂的催化性能.与未改性催化剂相比,Zn改性的催化剂在相同转化率条件下,异辛烷的选择性基本相同,但是二甲基己烷的选择性明显提高.当Zn的添加量为0.5%时,二甲基己烷选择性达到最大值,继续提高Zn的添加量,其选择性下降.值得注意的是,在相同反应条件下,未改性的催化剂具有更高的正辛烷转化率.我们分析认为,由于Zn的添加促进了二甲基己烷的产生,而其具有较大的分子尺寸,在反应中存在扩散问题,影响了改性催化剂的异构化活性.本文工作表明,适宜的Zn添加量有利于提高二甲基烷烃的选择性,对于提高汽油辛烷值具有重要意义.     

Zn改性的Pt/SAPO-11催化剂及其提高二甲基烷烃选择性

随着环保法规的日益苛刻,世界各国对发动机燃料指标的要求也越来越严格,汽油组分中的烯烃含量逐渐被限制.作为提高汽油辛烷值的有效手段,正构烷烃的临氢异构化越来越引起人们的重视.烷烃碳数相同时,具有多支链的异构体往往具有更高的辛烷值.因此,在正构烷烃临氢异构化过程中,提高多支链异构体的选择性具有重要意义.Pt/SAPO-11作为双功能催化剂具有适宜的孔结构、温和的酸性和适度的加氢脱氢活性,在烷烃临氢异构化反应中表现出色,得到了广泛研究.已有文献报道中,通过添加第二金属改性可以调节双功能催化剂的物理化学性质,进而影响其催化活性和产物选择性.为了提高异构产物选择性,特别是多支链异构产物的选择性,本文研究了Zn改性的Pt/SAPO-11催化剂在正辛烷临氢异构化中的反应性能,与未改性的Pt/SAPO-11催化剂相比,Zn改性的Pt/SAPO-11催化剂表现出更高的二甲基烷烃选择性.通过动态合成方法合成SAPO-11分子筛,进而制备Zn改性的Pt/SAPO-11催化剂.XRD表征表明,Pt和Zn的引入基本没有引起SAPO-11特征峰改变,并且未发现Pt和Zn氧化物的特征峰,说明金属组分得到很好的分散.氮气吸附-脱附实验表明,随着Zn添加量的增加,载体的比表面积和孔体积略有减少.NH3-TPD和吡啶红外光谱用于表征Zn的加入对催化剂酸性的影响,结果表明,少量Zn的添加可以增加酸量,这是由于Zn的引入可以产生L酸性位;而随着Zn的增加,总酸量减少,这是由于过多的Zn覆盖了载体的酸性位.H2-TPR和H2-TPD表征发现,Zn的引入使得Pt在高温处的还原峰减小,说明Zn改变了Pt在载体上的位置,使其主要负载在分子筛外表面.由于Zn2+是阳离子并具有较小的离子半径,它可以作为竞争吸附剂,首先进入分子筛孔道从而抑制了Pt进入分子筛孔道.H2-TPD表明,Zn的引入使得H2的脱附温度逐渐降低,这与Zn增加了Pt的分散度有关;但是当Zn的添加量达到0.7%时,H2的脱附温度升高,同时溢流氢增加.以正辛烷为模型化合物,在固定床高压微型反应装置中对一系列催化剂进行了评价,考察了Zn改性的Pt/SAPO-11催化剂和未改性的Pt/SAPO-11催化剂的催化性能.与未改性催化剂相比,Zn改性的催化剂在相同转化率条件下,异辛烷的选择性基本相同,但是二甲基己烷的选择性明显提高.当Zn的添加量为0.5%时,二甲基己烷选择性达到最大值,继续提高Zn的添加量,其选择性下降.值得注意的是,在相同反应条件下,未改性的催化剂具有更高的正辛烷转化率.我们分析认为,由于Zn的添加促进了二甲基己烷的产生,而其具有较大的分子尺寸,在反应中存在扩散问题,影响了改性催化剂的异构化活性.本文工作表明,适宜的Zn添加量有利于提高二甲基烷烃的选择性,对于提高汽油辛烷值具有重要意义.     

SAPO-11/Beta复合分子筛的合成及其异构化性能研究

以Beta分子筛为硅源通过水热合成法合成了SAPO-11/Beta复合分子筛,采用X射线衍射、N2物理吸脱附、扫描电镜、透视电镜-能谱分析、固体核磁及吡啶红外等方法对单分子筛、复合分子筛和机械混合分子筛的物化性质进行了表征.以正十二烷为模型化合物,在固定床反应器上考察了铂负载型分子筛催化剂的异构化性能.结果表明,复合分子筛的物理化学性质明显不同于单分子筛和机械混合分子筛,其呈现核壳结构,SAPO-11和Beta间存在化学作用,使得复合分子筛具有适宜的B酸分布.在正十二烷异构化反应中,复合分子筛催化剂的异构化性能优于单分子筛催化剂和机械混合分子筛催化剂,多支链异构体收率高.     

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%).     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.