高表面积复合氧化物Co-O-Si的制备及其催化1-己烯骨架异构和噻吩加氢脱硫活性

通过硝酸钴与硅酸钠共沉淀、辅以正丁醇干燥技术制备了具有原子分散度的Co-O-Si复合氧化物（Co/Si原子比 ≈ 0.65）,该催化剂具有较大的比表面积（562 m²/g）和较强表面酸性. 在硫化处理后,能够形成高度分散的硫化物活性组分,在模型汽油加氢处理反应中显示了较高的催化活性,在573 K时,噻吩的加氢脱硫活性可达99.4%,同时,1-己烯的骨架异构收率达到了35%. 该催化剂虽然不含Mo,其加氢脱硫活性可与工业催化剂Co-Mo/γ-Al₂O₃相当. 而在汽油深度加氢脱硫过程中,直链烯烃往往被加氢饱和,造成辛烷值损失. 该催化剂则可使部分直链烯烃发生骨架异构而生成异构烷烃,可减少深度加氢脱硫过程中的辛烷值损失.     

CO吸附原位红外光谱结合分子模拟计算研究FCC汽油加氢脱硫催化剂的选择性

以脱硫选择性不同的2组催化裂化汽油加氢脱硫催化剂为研究对象, 采用CO吸附原位红外光谱表征了2组催化剂的活性相特征, 并通过分子模拟计算方法比较了助剂Co加入前后噻吩和1-己烯在催化剂表面的电荷分布、吸附能及其加氢反应的活化能等, 探讨了助剂Co的加入对选择性加氢脱硫催化剂脱硫选择性的作用机理. 结果表明, 加氢脱硫催化剂CoMoS活性相的增加有利于提高催化剂的加氢脱硫/加氢降烯烃(HDS/HYD)选择性. 与1-己烯加氢位相比, Co的加入显著提高了噻吩分子加氢位的缺电子性, 噻吩在催化剂表面的吸附度增强, 显著降低噻吩加氢反应的能垒, 从而使噻吩加氢反应更易进行. 这也表明CoMoS为高HDS活性、高HDS/HYD选择性的活性相.     

APTS改性SBA-15负载Ni-B非晶态合金催化加氢脱硫性能的研究

采用共价接枝法制备APTS改性介孔分子筛SBA-15,将氨基官能团接枝到SBA-15表面.并采用化学还原法制备了Ni-B/SBA-15-APTS非晶态合金催化剂,以噻吩加氢脱硫为探针反应,研究了其催化加氢脱硫性能.结果表明,240℃时,APTS改性SBA-15所负载的Ni-B催化剂噻吩转化率达到50.8%,较未改性SBA-15所负载的催化剂噻吩转化率有显著地提高.由于氨基与Ni2+的配合作用,有助于Ni在催化剂中的分散,因而更容易被还原.ICP结果表明,在相同的制备条件下,相比未改性的SBA-15,APTS改性SBA-15使其催化剂中Ni的负载量增加,并且非晶态合金组成中Ni的含量也增大,B的含量降低,有利于提高催化剂的活性.     

Preparation and Hydrodesulfurization Performance of Ni-B Amorphous Alloy Catalyst Supported by APTS Modified SBA-15

采用共价接枝法制备APTS改性介孔分子筛SBA-15,将氨基官能团接枝到SBA-15表面.并采用化学还原法制备了Ni-B/SBA-15-APTS非晶态合金催化剂,以噻吩加氢脱硫为探针反应,研究了其催化加氢脱硫性能.结果表明,240℃时,APTS改性SBA-15所负载的Ni-B催化剂噻吩转化率达到50.8%,较未改性SBA-15所负载的催化剂噻吩转化率有显著地提高.由于氨基与Ni2＋的配合作用,有助于Ni在催化剂中的分散,因而更容易被还原.ICP结果表明,在相同的制备条件下,相比未改性的SBA-15,APTS改性SBA-15使其催化剂中Ni的负载量增加,并且非晶态合金组成中Ni的含量也增大,B的含量降低,有利于提高催化剂的活性.     

Mo-Ni2P/SBA-15催化剂的制备、表征及加氢脱硫催化性能

以介孔分子筛SBA-15 为载体, 通过分步浸渍硝酸镍、磷酸氢二铵、钼酸铵, 然后在H₂气流下程序升温还原(H₂-TPR), 制备了一系列不同Mo 含量的Mo-Ni₂P/SBA-15 催化剂. 采用X 射线衍射(XRD)、氮气吸脱附(BET)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)对催化剂的结构进行了表征, 评价了催化剂对二苯并噻吩(DBT)的加氢脱硫(HDS)活性. 结果表明, Mo-Ni₂P/SBA-15 催化剂仍然保留有介孔结构, 催化剂的物相主要是Ni₂P. 催化剂表面的Ni 以Ni^δ+和Ni²⁺形式存在; P以P^δ-和P⁵⁺形式存在; Mo以Mo^δ+和Mo⁶⁺形式存在. Mo能促进催化性能的提高, 其中Mo含量为1% (w, 质量分数)的Mo-Ni₂P/SBA-15 催化剂具有最好的二苯并噻吩加氢脱硫催化活性, 在反应温度为380 ℃, 反应压力为3.0 MPa的条件下, 二苯并噻吩的转化率可达99.03%, 所有考察的Mo-Ni₂P/SBA-15都以直接加氢脱硫(DDS)途径为主.     

Mo助剂含量对Mo-Ni2P/SBA-15/堇青石整体式催化剂加氢脱硫性能的影响

 采用共浸渍法制备了 P/Ni 摩尔比为 2 的 Ni2P/SBA-15, 再通过二次浸渍引入助剂 Mo 制得 Mo-Ni2P/SBA-15, 将它调制成活性胶后均匀涂敷于预处理后的载体表面, 干燥焙烧后在氢气流中采用程序升温还原法, 制备了一系列 Mo-Ni2P/SBA-15/堇青石整体式催化剂. 采用 X 射线衍射、N2 吸附-脱附和 X 射线光电子能谱对催化剂结构进行了表征, 以二苯并噻吩为模型含硫化合物, 考察了催化剂的加氢脱硫性能. 结果表明, Mo 的加入增大了催化剂的比表面积, 在催化剂表面形成了 MoNiP2, 且 Ni2P 为主要活性物相. Mo 在催化剂表面主要以 Mo6+和 Moδ+形式存在; 当 w(Mo) = 4.2% 时, n(Mo)/n(Ni+Mo) = 0.18 的整体式催化剂上二苯并噻吩的转化率最高, 且在较低反应温度时以直接脱硫机理为主, 而较高反应温度时以加氢脱硫机理为主.     

新型Ni-Mo/Al2O3加氢脱硫催化剂的研究

采用溶胶凝胶技术,制备了双结构Al2O3载体,用此改性载体制备了Ni-Mo/Al2O3催化剂,在中压固定床微反装置上考察了载体改性对催化剂上噻吩加氢脱硫(HDS)活性的影响,并用X射线粉末衍射、透射电镜、吡啶-红外光谱等分析方法对改性载体和催化剂进行了表征。结果表明,由铝溶胶改性载体制备催化剂的加氢脱硫活性均高于未改性载体制备的催化剂的催化活性。XRD和TEM结果表明氧化铝表面负载的铝溶胶经过干燥、焙烧后以纳米尺度的η-Al2O3状态存在,吡啶-红外光谱结果表明,改性氧化铝载体制备催化剂的弱B酸和弱L酸的酸量均提高,强L酸的酸量也明显增加。酸性、酸量的提高和纳米尺度η-Al2O3的存在是催化剂活性提高的主要原因。     

活性炭负载的Co-Mo催化剂的加氢脱硫性能 Ⅰ.活性炭载体与γ-Al2O3的对比

 用XRD,TPR和XPS技术对Co-Mo/AC(活性炭)和Co-Mo/γ-Al2O3催化剂进行了表征,并以二苯并噻吩HDS反应评价了催化剂的活性. 在不同温度下处理的催化剂,其活性组分高度分散在活性炭表面,未检测到明显的Mo和Co物种. 在Co-Mo/AC催化剂中,表面物种的还原温度低于Co-Mo/γ-Al2O3的还原温度. 在260 ℃下处理的Co-Mo/AC催化剂,其表面Mo是高价态的Mo(Ⅵ),在500 ℃下处理的Co-Mo/AC催化剂,其表面存在Mo(Ⅴ)和Mo(Ⅵ)两种价态. 硫化态CoMoS/AC催化剂中存在Mo(Ⅳ)和Mo(Ⅴ)两种低价态的Mo物种,而S主要以S2-2和S2-的形式存在于MoS2和MoO3S2-中,还有部分高价态的S6+. 在硫化态CoMoS/γ-Al2O3催化剂中,Mo主要以Mo(Ⅴ)和Mo(Ⅵ)两种状态存在,而S主要以S2-2或S2-的形式存在于MoO2S2-和MoO3S2- 中,还有部分高价态的S6+. 活性评价结果表明,n(Co)/n(Mo)=0.7的Co-Mo/AC的活性高于Co-Mo/γ-Al2O3的活性,而其他Co/Mo比的Co-Mo/AC的活性低于Co-Mo/γ-Al2O3的活性.     

硫代硫酸铵预硫化的Mo/AC催化剂加氢脱硫性能的研究

采用等体积浸渍法将硫代硫酸铵(ATS)负载在Mo/AC催化剂上,制备了器外预硫化的Mo/AC-ATS催化剂;以噻吩加氢脱硫(HDS)为探针反应,考察了活化温度和活化时间对预硫化催化剂加氢脱硫活性的影响。研究发现,300 ℃下活化0.5 h所得到的预硫化催化剂具有最好的加氢脱硫活性。与传统硫化剂CS₂和DMDS硫化的催化剂相比,采用Mo/AC-ATS催化剂,在最佳活化条件下,噻吩转化率分别提高了34%和42%。XPS、TPR-MS和TEM等表征结果显示,预硫化的Mo/AC-ATS催化剂中Mo⁴⁺含量较高,这是其具有较高加氢脱硫活性的主要原因。     

Co、Mo掺杂对Ni／ZnO—ZrO2催化剂催化噻吩加氢脱硫性能的影响

采用固相合成法制备了ZnO—ZrO2载体,并采用浸渍法制备了镍基催化剂,以噻吩加氢脱硫反应为探针考察了Co、Mo的掺杂对Ni／ZnO—ZrO2催化性能的影响．采用NH,吸附红外光谱（IR）、程序升温脱附（TPD）、程序升温还原（TPR）、X射线衍射（XRD）等技术对催化剂进行了表征．研究结果表明,ZnO－ZrO2复合载体对噻吩加氢脱硫反应有一定的活性,反应温度为400℃时噻吩转化率为6．4％;Co的加入提高了Ni／ZnO-ZrO2的催化活性,噻吩转化率可达97．3％;相反,Mo的掺杂则降低了Ni／ZnO—ZrO2的催化活性,噻吩转化率为65．0％．这是由于Co的掺杂使活性组分Ni分散度提高,氧化态的Ni变得容易还原,在同样的还原条件下催化剂表面有更多的活性中心;而Mo掺杂则使Ni／ZnO—ZrO2催化剂中氧化态的Ni变得难以还原,部分以NiO形式存在,活性中心数量减少．三种催化剂表面均存在L酸中心,Co掺杂使Ni／ZnO-ZrO2催化剂表面弱酸中心和中等强度酸中心的强度及数量均增大．No掺杂则减弱了催化剂表面弱酸中心和中强酸中心的强度．对其酸量则影响不大．     

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%.     

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.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.