溶胶-凝胶法制备还原态K-Co-Mo催化剂的合成醇性能

应用溶胶-凝胶法制备了还原态K-Co-Mo催化剂, 比较了不同的组分和不同的反应条件对合成醇性能的影响。实验结果表明，适量钾和钴助剂的添加能显著提高催化剂合成醇的性能，尤其是提高了C2+醇的选择性。此外，反应温度、压力以及空速对合成醇影响明显，升高温度可以提高催化反应中低碳醇的收率，但选择性下降；增加压力和空速可以提高低碳醇的收率和选择性，对合成低碳醇有利。在230 ℃，6.0 MPa，14 400 h－1条件下，催化剂合成低碳醇的收率为375.4 g/kg·h，选择性为70.2%，C1OH/C2+OH为0.48。     

Mn改性Ni/K/MoS2合成低碳醇催化剂反应性能研究

以不同的添加方式在Ni/K/MoS2催化剂中加入Mn助剂，考察其合成醇反应性能。结果表明，Mn/Ni/K/MoS2催化剂具有较好的合成低碳混合醇反应性能。共沉淀法以醋酸锰为前驱体加入0.6%的Mn助剂后，C2+含量，醇时空产率及选择性均明显提高;分步沉淀法使Mn的加入量增加到0.6%，醇时空产率明显增加。以浸渍法按化学计量加入Mn助剂考察其含量对催化剂合成醇性能的影响，当Mn/Mo（原子比）为1∶时，反应条件为315 ℃, 9.5 MPa, 6 000 h－1，醇时空产率和醇选择性分别达到最高值0.338?g/mL·h和69.6%。300 h的稳定性测试结果表明，共沉淀法改性的催化剂具有良好的稳定性。     

常压两步法催化丙三醇脱水-加氢制备 1,2-丙二醇

 在常压 H2 气氛下催化丙三醇脱水-加氢制备了 1,2-丙二醇. 首先在 220 oC 和常压 H2 条件下, 以 Cu/Al2O3 为催化剂催化丙三醇脱水生成中间体丙酮醇, 其选择性高达 86%. 考察了 Cu 负载量、反应温度和反应气氛对催化剂性能的影响. 在随后的丙酮醇加氢反应中, Raney Ni 催化剂显示出优异的催化性能, 在 120 oC 和常压 H2 条件下, 1,2-丙二醇选择性可达 99% 以上, 催化剂连续使用 5 h 未出现失活现象. 考察了反应温度、空速及反应时间对催化剂性能的影响.     

还原温度对超细K－Co－Mo催化剂合成低碳醇性能的影响

 用溶胶－凝胶法合成了K－Co－Mo催化剂．样品经不同温度还原后，用于低碳醇的合成．XRD和HRTEM结果表明，样品是超细粒子，粒子尺寸为2～5nm．考察了催化剂的还原温度和反应条件对催化剂性能的影响．实验结果表明，还原温度对催化剂的活性有较大的影响，最佳还原温度为500℃．最佳反应温度范围为310～330℃．升高压力和空速可以提高醇的收率和选择性．在空速14400h－1，压力6．0MPa和温度310℃的条件下，醇的选择性为55．8％，收率为520．0g／（kg·h），MeOH／C2＋OH为0．27．催化剂稳定性良好，在200h的寿命实验中，活性基本不变．与文献中催化剂相比，超细K－Co－Mo催化剂对合成醇具有较高的活性和选择性，尤其是对C2＋OH的合成明显高于其他合成醇催化剂体系．     

合成气制低碳混合醇耐硫钼基催化剂的制备研究

本文考察了不同制备方法和制备程序制得之MoSx-K^ /Si O2催化剂对合成转化为低碳混合醇的催化性能，探讨不同助剂（包括K2 CO3，KF，DC1等）对催化剂活性和选择性的影响，首次报道以K2MoS4作为前驱物料制得的MoSx-K^ /SiO2催化剂具有与（NH4）2MoS4- K2CO3/SiO2和法生得到的催化剂几乎一样高的催化活性 和选择性 ，其结果为具有实用意义的催化剂的研制提供依据。     

K改性β-Mo2C催化剂CO加氢合成低碳混合醇的研究

制备系列K改性的β-Mo2C催化剂并对其CO加氢合成低碳混合醇性能进行了考察。结果表明，K改性使β-Mo2C催化剂的CO加氢选择性发生显著变化。β-Mo2C催化剂CO加氢的产物主要为C1～C4烷烃,经K改性后β-Mo2C催化剂上产物主要为C1～C5低碳醇，其中高级醇(C2+OH)选择性可达到33.78%。通过对碱金属质量分数的考察发现，当K/Mo（原子比）为0.2时，总醇选择性达到最大值，低碳醇的时空收率达到0.12 g/（mL·h－１）。β-Mo2C催化剂上醇烃产物均符合线性Anderson-Schultz-Flory（A-S-F）分布曲线，而K改性β-Mo2C催化剂上醇产物为独特的甲醇负偏离A-S-F分布。可见，K助剂的加入有效促进了低碳醇的形成，尤其是促进了C1OH到C2OH的链增长步骤。     

活性炭负载钴基催化剂上合成气制混合醇

在两种分别来自椰壳炭和杏核炭的活性炭AC1和AC2上,采用真空浸渍法制备了Co基催化剂15%Co/AC1和15Co%/AC2,并考察了其在CO氢化反应中的催化性能.结果表明,AC1和AC2的孔结构基本相同,但表面含氧官能团的数量和种类不同.含氧官能团影响了催化剂Co物种的形态,从而使催化剂在反应中表现出不同的性能.助剂K和zr的添加改变了15%Co/AC1催化剂的活性和选择性.在3.0 Mpa,495 K,H2/CO(体积比)=2和GHSV=500 h-1反应条件下,15%Co/AC1和15%Co/AC2上C1～C18醇的选择性分别为20.6%和9.6%.在其它条件不变,GHSV=1500 h.反应条件下,15%Co-0.01%K-2%Zr/AC1催化剂上CO转化率和醇选择性分别为28.0%和34.3%,液相产物中醇占60.9%,其中C6～C18高碳醇占液相产物的20.6%.     

铁的添加方式对Cu-Mn/ZrO2合成低碳醇催化剂的影响

采用浸渍和共沉淀两种方法制备了Fe/Cu/Mn/ZrO2催化剂,考察了Fe的添加方式对催化剂反应性能的影响,发现添加方式的不同使催化剂的整体性能有较大的改变,在温和条件下,浸渍法制备的催化剂醇的时空收率可达0.26g/mL*h,其中C2+OH的选择性约为22%,产物以直链醇为主,催化剂的活性和选择性均高于同等Fe浓度的共沉淀催化剂.用EXAFS研究了催化剂的表面状况,发现浸渍法制备催化剂促进了Cu的高度分散,从而提高了催化剂的催化性能.     

新型K/αMoC 1－x 催化剂CO加氢合成低碳混合醇的研究

制备K改性的αMoC1－x催化剂并对其CO加氢合成低碳混合醇性能进行了考察。结果表明，K改性使αMoC1－x催化剂的CO加氢选择性发生显著变化。αMoC1－x 催化剂CO加氢的产物主要为CO2和C1~4烷烃,同时有少量醇产物生成；经K改性后αMoC1－x催化剂产物中烷烃选择性明显降低，而C1~5低碳醇选择性显著提高。通过对碱金属质量分数的考察发现，当K/Mo（摩尔比）为0.1时，总醇选择性达到极大值，低碳醇的时空收率达到28.6g/（L·h）。αMoC1－x催化剂上醇烃产物符合线性A-S-F分布曲线，K改性αMoC1－x催化剂上醇烃产物也有类似A-S-F分布曲线，但K助剂的加入有效促进了低碳醇的形成及其链增长能力。结合XRD、SEM及XPS表征，K助剂与αMoC1－x催化剂主体之间的电子作用导致其CO加氢产物选择性发生显著变化，这与K/αMoC1－x催化剂表面“K-Mo-C”新相的生成有关。     

Ru/ZrO2·xH2O催化剂催化肉桂醛选择性加氢制肉桂醇

采用共沉淀法制备了7.5%Ru/ZrO2·xH2O催化剂,运用N2物理吸附-脱附法、X射线衍射、X射线光电子能谱和高分辨透射电子显微镜等技术对催化剂进行了表征,并用于催化肉桂醛选择加氢制肉桂醇反应中,考察了温度、H2压力和溶剂对肉桂醛转化率和肉桂醇选择性的影响.结果表明,肉桂醛转化率随着温度或H2压力的升高而升高,而肉桂醇选择性则随之下降.该催化剂在极性溶剂中比在非极性溶剂中表现出更高的活性和肉桂醇选择性.尤其在极性溶剂三乙胺(Et3N)中反应活性最高,且具有较高的肉桂醇选择性.在Et3N中加入水可进一步提高反应活性和选择性.以V(Et3N)/V(H2O)=4的混合物为溶剂,在4MPa和70℃的优化条件下,反应6h,肉桂醛转化率为97.9%,肉桂醇选择性达85.2%.     

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%).     

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.     

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.     

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.