CuO-ZnO基CO2/H2合成甲醇催化剂的反应活性中心

应用 ＸＰＳ，ＸＡＥＳ和紫外漫反射光谱法研究了ＣｕＯ－ＺｎＯ／氧化物上ＣＯ２／Ｈ２合成甲醇的反应活性中心。ＣｕＯ－ＺｎＯ／氧化物催化剂上的反应活性中心是存在于ＣｕＯ－ＺｎＯ固溶体中的Ｃｕ－口－Ｚｎ－Ｏ（＂口＂为氧空位），活性中心的Ｃｕ价态为Ｃｕ＾＋和Ｃｕ＾０。反应活性中心在ＣｕＯ－ＺｎＯ－Ｚｒｏ２催化剂上比在其它ＣｕＯ－ＺｎＯ／氧化物催化剂如ＣｕＯ－ＺｎＯ，ＣｕＯ－ＺｎＯ－ＭｇＯ，ＣｕＯ－ＺｎＯ－     

二氧化碳加氢合成甲醇铜基催化剂表面组成的研究

本文分别采用ＸＲＤ、ＥＳＲ、ＸＰＳ和ＸＡＥＳ等技术对于二氧化碳加氢低压合成甲醇用ＣｕＯ，ＣｕＯ－ＺｎＯ，ＣｕＯ－ＺｎＯ－Ａｌ＿２Ｏ＿３，ＣｕＯ－ＺｎＯ－ＺｒＯ＿２催化剂在不同条件下表面Ｃｕ、Ｚｎ、Ａｌ、Ｚｒ的存在价态进行了深入分析。实验发现催化剂在还原前Ｃｕ以Ｃｕ￣２＋存在，在还原后和反应状态下以Ｃｕ￣０存在；Ｚｎ在还原后和反应状态下有部分被还原为Ｚｎ￣（２－δ）（０＜δ＜２），Ｚｒ和Ａｌ仍保持其还原前价态。催化剂的表面化学组成为：Ｃｕ￣０／Ｚｎ（２－δ）￣＋／Ｚｒ￣４＋／Ａｌ￣３＋／Ｏ￣２－。     

CO2加H2合成甲醇Cu—Zn—O催化剂表面化学态研究

应用ＸＲＤ、ＥＳＲ、ＵＲＤＳ、ＸＰＳ及ＸＡＥＳ等手段研究了ＣＯ２加Ｈ２合成甲醇Ｃｕ－Ｚｎ－Ｏ催化剂在还原后和反应状态下的表面化学状态。结果表明，在还原及反应状态下，催化剂表面仅能检测到ＣＵ＾０，而未发现稳定的Ｃｕ＾２＋和Ｃｕ＾＋存在；ＺｎＯ被 部分还原产生低价锌Ｚｎ＾（２－δ）＋（０＜δ＜２）。关联活性测试结果认为：Ｃｕ＾ｏ／Ｚｎ＾（２－δ）＋Ｏ构成ＣＯ２加Ｈ２合成甲醇反应的活性中心。     

助剂对超细CuO－ZnO－SiO_2催化剂性质和CO_2加氢反应性能的影响

研究了９种助剂对用于ＣＯ２加氢反应的超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂性能的影响，并进行了ＸＲＤ和ＴＰＲ表征．结果表明，助剂影响超细催化剂的性质和催化性能，ＴｉＯ２、ＣｅＯ２、ＭｇＯ和Ｌａ２Ｏ３是ＣＯ２加氢合成甲醇的超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂体系的优良助剂．在含有不同助剂的ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂体系内存在ＣｕＯ和ＺｎＯ晶相，但除ＣｅＯ２以外，其它的助剂都可能以微晶或无定型的形式存在．ＴＰＲ研究表明，添加的助剂除ＣｅＯ２以外，都使超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂的还原温度提高，而且助剂对ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂活性的影响，按照助剂对ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂还原温度的影响进行了探讨     

Cu／ZnO／Al_2O_3／ZrO_2催化剂上乙醇脱氢合成乙酸乙酯Ⅱ．催化剂的表征

采用ＸＲＤ，ＴＰＲ和ＴＰＤ／ＴＰＳＲ方法研究了ＣｕＯ／ＺｎＯ／Ａｌ２Ｏ３／ＺｒＯ２（及还原态）催化剂的物相结构、还原状况、酸碱性质及吸附状况，并与其它催化剂作了比较．ＸＲＤ结果表明，此催化剂在还原前有以晶相存在的ＣｕＯ，还原后以铜晶形式存在，而Ａｌ２Ｏ３，ＺｎＯ，ＺｒＯ２在还原前后均以无定形形式存在．ＴＰＲ实验发现，共沉淀法制备的铜基催化剂只有一个耗氢峰，对应ＣｕＯ的一种分布状态，且催化剂中ＺｒＯ２的存在促进了催化剂的还原．ＮＨ３－ＣＯ２双组分共吸附结果表明，ＣｕＯ／ＺｎＯ／Ａｌ２Ｏ３／ＺｒＯ２催化剂上有两种强度不同的酸中心（１００℃，３４０℃）及弱碱中心（９０℃）．乙醇在催化剂上的ＴＰＳＲ结果表明，在１１０℃有乙醇的脱附峰，氢气及乙醛的生成峰在２１０℃，而在高温时则有ＣＯ，ＣＯ２及丙酮的脱附，整个过程中仅检测到微量乙酸乙酯的脱附（ｍ／ｅ＝４３）     

甲烷部分氧化制合成气Ⅱ．镍系催化剂的反应性能

主要用第四周期金属元素的氧化物与Ａｌ２Ｏ３的复合氧化物催化剂上甲烷氧化的结果证实了催化剂设计中的预测：（１）催化剂首先应能解离活化甲烷，（２）催化剂要能较快地活化Ｏ２分子．只有同时满足这两个条件，催化剂才可能有较好的甲烷部分氧化活性．第四周期元素中只有镍具有这样的性质．Ｃｕ，Ｍｎ，Ｃｒ，Ｌａ，Ｃａ，Ｚｎ等氧化物的添加可明显提高Ｎｉ－Ａｌ２Ｏ３催化剂的甲烷部分氧化性能，其中Ｃｕ的助催化性能最好．催化剂ＮｉＯ－ＣｕＯ－Ａｌ２Ｏ３，ＮｉＯ－ＭｎＯ－Ａｌ２Ｏ３，ＮｉＯ－Ｃｒ２Ｏ３－Ａｌ２Ｏ３的反应活性和选择性顺序，与金属Ｃｕ，Ｍｎ，Ｃｒ上ＣＯ和Ｈ２脱附的顺序是一致的     

甲醇与乙醇一步合成异丁醛用CuO-ZnO/Al2O3催化剂

在ＣｕＯ－ＺｎＯ／Ａｌ２Ｏ３催化剂上，甲醇与乙醇在常压和２１０￣３６０℃温度下一步反应合成异丁醛。利用正交设计方法，研究了ＣｕＯ－ＺｎＯ／Ａｌ２Ｏ３体系催化剂组成和制备条件等因素对催化剂催化性能的影响。结果表明，催化剂中ＣｕＯ含量对催化剂的催化活性影响最大，而ＺｎＯ含量则主要影响催化剂对异丁醛的选择性。催化剂制备条件，如沉淀温度、陈化时间等，也不同程度也影响催化剂的催化性能。ＸＲＤ和ＢＥＴ表征结果     

Cu／ZnO／Al_2O_3／ZrO_2催化剂上乙醇脱氢合成乙酸乙酯Ⅰ．催化反应性能及机理

研究了经ＺｒＯ２改性的Ｃｕ／ＺｎＯ／Ａｌ２Ｏ３的催化性能，考察了操作条件、ＺｒＯ２含量及不同原料的影响．发现经共沉淀法制备的Ｃｕ／ＺｎＯ／Ａｌ２Ｏ３／ＺｒＯ２具有最佳的反应活性及选择性．以９５％乙醇为原料，在２６５℃，ＷＨＳＶ１．５ｈ－１时，乙醇转化率为６９．０％，乙酸乙酯选择性为７０．２％．使用无水乙醇为原料要好于９５％乙醇，使用乙醛或醇醛混合原料，亦有乙酸乙酯生成．乙醇在此催化剂上的反应机理为乙醇先在Ｃｕ上脱氢为乙醛，然后乙醛在酸碱双中心上发生Ｃａｎｎｉｚａｒｒｏ反应生成乙酸乙酯．还讨论了ＺｒＯ２的作用及催化剂活性降低的原因     

氧化锆对铜基甲醇合成催化剂的促进作用(英文)

采用离子掺杂价态补偿原理,在Ｃｕ－Ｚｎ－Ａｌ甲醇合成催化剂中添加适量氧化锆助剂研制Ｃｕ－Ｚｎ－Ａｌ－Ｚｒ催化剂的特性。实验结果表明,最佳反应温度为２３０℃,比Ｃｕ－Ｚｎ－Ａｌ约低１０℃。采用ＸＲＤ、ＵＶＤＲ、ＦＴＩＲ、ＴＰＤ和ＴＰＲ等谱学方法对２种催化剂进行表征显示,铜基催化剂的活性位可能是“Ｃｕ０－Ｃｕ＋－Ｏ－Ｚｎ２／Ａ２Ｏ３－ＺｒＯ２”,工作态Ｃｕ－Ｚｎ－Ａｌ－Ｚｒ催化剂表面上Ｃｕ／Ｃｕ０的比值、价态稳定性和对ＣＯ的吸附量均大于Ｃｕ－Ｚｎ－Ａｌ,这与该催化剂具有较好的低温活性和较高的热稳定性密切相关。     

助剂对超细CuO—ZnO—SiO2催化剂性质和CO2加氢反应性能的影响

研究了９种助剂对用于ＣＯ２加氢反应的超细ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂性能的影响，并进行了ＸＲＤ和ＴＰＲ表征，结果表明，助剂影响超细催化剂的性质和催化性能，ＴｉＯ２、ＣｅＯ２、ＭｇＯ和Ｌａ２Ｏ３是ＣＯ２加氢合成的超细ＣｕＯ２－ＺｎＯ－ＳｉＯ２催化剂体系的优良助剂，在含有不同助剂的ＣｕＯ－ＺｎＯ－ＳｉＯ２催化剂体系内存在ＣｕＯ和ＺｎＯ２晶相，但除ＣｅＯ２以外，其它的助剂都可能以微晶或无定型的形式存在     

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.