Synthesis of complex hydroxo salts of magnesium, nickel, cobalt, aluminum, and bismuth and oxide catalysts on their base

Synthesis methods have been developed for the precursors of oxide catalysts that include the combination of magnesium nickel cobalt aluminum hydroxocarbonate, with a layered hydrotalcite-type structure and decavanadate and paramolybdate ions in the anion layers, and bismuth hydroxocarbonate. On the base of these precursors, multicomponent oxide catalysts have been manufactured for the oxidative dehydrogenation (OD) of light alkanes. Some of these catalysts showed high selectivities and high product yields in the conversion of ethane to ethylene.     

醇预处理载体制备的 Ir-Re/SiO2催化剂上甘油氢解反应

甘油是生物柴油的副产物,将其转化为高附加值的化学品,能提高生物柴油产业的经济性.1,3-丙二醇是聚酯和聚氨酯的单体,也用于合成医药和用作有机合成中间体,甘油直接催化氢解反应制1,3-丙二醇极具发展潜力.另外,甘油是生物质转化的重要平台分子之一,与目标产物的分子结构相比较,生物质平台分子通常含有过多的含氧基团,尤其是多余的羟基,通过甘油氢解反应研究多羟基的选择性活化和脱除,可以加深对生物质脱氧规律的认识.因此,研究甘油氢解反应制1,3-丙二醇催化剂和工艺,不仅具有潜在的应用前景,而且具有重要理论价值.然而,目前的甘油氢解催化剂性能还不够高,我们希望通过一些表面改性的方法处理载体硅胶,从而改变金属前驱体与载体表面的作用.因此,本文使用 C1–C4的正构醇处理硅胶载体,其负载的 Ir-Re催化剂上甘油氢解反应转化率从42.7%提高到59.5%,仲羟基脱除收率从21.6%提高到28.3%.研究发现,当处理载体所用正构醇的碳数从1增加到3时,对应催化剂上甘油转化率逐渐增加至最高;但当使用更正丁醇时,对应催化剂上甘油转化率下降.为了探究催化剂活性改变的原因,我们首先采用红外光谱(FT-IR)和氮气物理吸附确定烷氧基基团嫁接到硅胶载体上.程序升温还原结果发现,预处理载体相应的催化剂开始还原温度降低,表明在这些催化剂上形成了颗粒尺寸较小的Ir粒子. X-射线衍射分析发现,在新鲜的和使用后的催化剂上均未检测出Re物种的衍射峰,说明Re高度分散于催化剂表面.吸附吡啶的FT-IR结果表明,未处理和丙醇预处理硅胶负载的催化剂上均没有强酸位,它们的B/L酸比值相近,约为3.3.催化剂的吸附COFT-IR结果表明, CO线性吸附于Ir/SiO2催化剂上的主要吸收峰位置在2084 cm–1;而Re的加入使得该吸收峰红移,表明Ir和ReOx物种之间存在相互作用.透射电镜(TEM)、H2-程序升温脱附和NH3-程序升温脱附结果发现,醇预处理催化剂上具有更多的Ir-ReOx界面,而界面位点的数量与甘油转化率大小一致,表明Ir-ReOx位点可能就是甘油氢解的活性中心.反应后催化剂的TEM结果表明,醇预处理催化剂上的Ir颗粒要小于未处理催化剂的,其中丙醇预处理硅胶负载的催化剂上Ir粒径最小.这是由于醇处理催化剂上存在很多孤立的Si–OH,它们与金属前驱体相互作用有利于形成较小的金属颗粒.这些孤立的Si-OH则是由于表面烷氧基基团的隔离作用所形成的.当处理载体所用正构醇的碳数从1增加到3时,烷氧基的碳链变长,分隔作用越好,阻止金属前驱体聚集的程度越强,因而Ir物种和Re物种的分散度增加.但是当处理醇的碳数增加到4时,形成的表面烷氧基基团可能阻止了Re物种和Ir物种间相互作用,从而使得Ir和Re物种的分散度均降低,相应催化剂活性随之降低.     

Niobium-containing catalysts for oxydehydrogenation of hydrocarbons and alcohols

The first methods are developed for introducing niobium(V) into Mg-Al hydrotalcites used as precursors of oxide catalysts for oxydehydrogenation (OD) of alkanes and alcohols. Samples of niobium(V)-containing oxide catalysts are synthesized. Their catalytic properties are studied in oxydehydrogenation of ethane and ethylbenzene to styrene, oxidation dehydrocyclization of octane into ethylbenzene and styrene, and oxydehydrogenation of sec-butanol to ketone (octane-(2)-one). It is ascertained that ethane transformation into ethylene is highly a selective highly process (92–97%) at low temperatures (450–500°C) in the presence of a niobium-containing catalyst; the catalyst is appreciably efficient in ethylbenzene transformation to styrene and dehydrocyclization of n-octane to ethylbenzene and styrene, and in oxydehydrogenation of secbutanol to octane-(2)-one. All the catalysts studied operate stably in OD reactions; no decrease in their activity or selectivity was detected after 50 h operation.     

K-Co-Mo-C催化剂的制备及其合成低碳醇的性能

 采用溶胶-凝胶法制备了含碳的K-Co-Mo-C催化剂,通过改变碳前驱体的添加量以获得不同的碳含量,测试了催化剂上合成气制混合醇的性能. 结果表明,适量的残留碳增加了催化剂中活性相的分散度,提高了合成醇的收率和选择性,但过量的碳导致烃的选择性增加而醇的选择性下降,这是由于随着碳前驱体添加量的增加,催化剂中的Mo物种更容易被还原成金属态. 与惰性气氛中焙烧的样品不同,空气中焙烧的样品中没有碳的存在,氧化物组分容易生成难以还原的物相,合成醇活性较低. 含碳量为2.8%的样品具有最大的比表面积和孔体积,同时也具有最高的醇收率和选择性. 惰性气氛中高温焙烧样品导致其合成醇活性明显降低,但同时高碳醇的选择性增加.     

Tantalum-containing catalysts for oxydehydrogenation of hydrocarbons and alcohols

The first methods were developed for introducing tantalum(V) into Mg-Al hydrotalcites, which are precursors of oxide catalysts for oxydehydrogenation of hydrocarbons and alcohols. Samples of oxide tantalum(V)-containing catalysts were synthesized. Their catalytic properties were studied in the oxydehydrogenation of ethane to ethylene and ethylbenzene to styrene, oxydehydrocyclization of octane to ethylbenzene and styrene, and oxydehydrogenation of sec-butanol to ketone (octan-2-one). The transformation of ethane to ethylene over the tantalum-containing catalyst occurs with a high selectivity (92–97%) at relatively low temperatures (500°C), and the catalyst is quite efficient in conversion of ethylbenzene to styrene, dehydrocyclization of n-octane to ethylbenzene and styrene, and oxydehydrogenation of sec-butanol to octan-2-one. Comparison with a niobium-containing catalyst showed that it ensures higher yields and selectivities in similar reactions than its tantalum-containing analogue does.     

Preparation of aliphatic ketones through a ruthenium-catalyzed tandem cross-metathesis/allylic alcohol isomerization

Grubbs' 2nd generation and Hoveyda-Grubbs' ruthenium alkylidenes are shown to be effective catalysts for cross-metatheses of allylic alcohols with cyclic and acyclic olefins, as well as isomerization of the resulting allylic alcohols to alkyl ketones. The net result of this new tandem methodology is a single-flask process that provides highly functionalized, ketone-containing products from simple allylic alcohol precursors. [reaction: see text]     

Ni-Mo氮化物催化剂:合成及其丙烷氨氧化催化性能简

分别采用溶胶-凝胶法、旋转蒸发微波干燥法、共沉淀法、浸渍法和机械混合法制备Ni-Mo氧化物前驱体. 以H₂和N₂的混合气为氮化气体,采用程序升温氮化法合成了镍钼氮化物催化剂. 利用X射线衍射、总氮含量分析、X射线光电子能谱及H₂程序升温还原对Ni-Mo氧化物前体及氮化物催化剂进行了表征. 将上述Ni-Mo氮化物催化剂用于丙烷氨氧化反应中. 结果表明,Ni-Mo氧化物前驱体的制备方法影响其氮化物催化剂上丙烷氨氧化反应性能. Ni-Mo氮化物催化剂中氮物种的移动性及反应性对产物丙烯腈选择性的影响较大,共沉淀法制备的催化剂存在大量的活性氮物种,因而具有良好的催化丙烷氨氧化反应活性.     

Europium oxide containing catalysts for oxidative dehydrogenation of alkanes

A method is developed to incorporate europium into Mg–Al hydrotalcites, which are precursors for oxide catalysts of oxidative dehydrogenation (ODH) of alkanes; samples of oxide catalysts are prepared, where europium oxide and gallium, magnesium, aluminum, chromium, vanadium, molybdenum, and niobium oxides are contained in various combinations. The catalytic properties of these catalysts in the reactions of ethane, propane, and butane ODH are studied. The incorporation of europium into some of our studied multicomponent catalysts enhances the reaction selectivity and increases yields of desired products.     

Mechanochemical synthesis of nanocrystalline nickel-molybdenum compounds and their morphology and application in catalysis: III. Catalytic properties of massive Ni-Mo sulfide catalysts synthesized using mechanochemical activation

The precursors of massive Ni-Mo catalysts for hydrotreating processes, which were synthesized by the mechanochemical activation of a mixture of nickel hydroxocarbonate NiCO₃·2Ni(OH)₂·nH₂O and ammonium paramolybdate (NH₄)₆Mo₇O₂₄ · 4H₂O, were sulfidized. Their structure was studied by X-ray diffraction analysis and high-resolution electron microscopy. It was found that MoS₂ packets, which are characterized by the presence of structural defects and geometric curvature, are the constituents of the massive catalysts. The catalyst also includes a phase of Ni₃S₂ and regions containing a complex Ni-Mo-S phase. The catalytic tests of the synthesized catalysts in the model reactions of 1-methylnaphthalene and dibenzothiophene conversions showed that the catalyst whose precursor was a heteropoly compound with the Anderson structure after the stage of mechanochemical activation exhibited the highest activity.     

以MOFs为前驱体的多孔金属氧化物催化剂研究进展

多孔金属氧化物具有高比表面积、大孔径、特殊的形貌和结构特性,广泛应用于催化、锂离子电池、太阳能电池、气敏传感器等领域。金属有机骨架材料(MOFs)是一类具有周期性网络结构的新型多孔晶体材料,在气体存储、气体分离、催化等领域具有重要的应用价值。近年来,以MOFs为前驱体制备多孔碳和多孔金属氧化物成为MOFs应用领域一个新的研究热点。本文主要综述了以MOFs为前驱体制备的多孔金属氧化物和多孔金属氧化物/碳复合物在CO氧化、催化产氢、异丁烷脱氢、环已烯氧化、醇直接氧化为酯、醛氧化酰胺化反应、光催化降解有机物和氧还原反应等方面的应用。     

Air-stable racemization catalysts for the dynamic kinetic resolution of secondary alcohols

The substitution of a carbonyl ligand with PPh(3) in cyclopentadienylruthenium dicarbonyl complexes produces a new class of recyclable alcohol racemization catalysts. The catalysts are active at room temperature under aerobic conditions in the presence of silver oxide. Furthermore, the catalysts are compatible with the use of a lipase and isopropenyl acetate for the dynamic kinetic resolution (DKR) of secondary alcohols under ambient conditions.     

Preparation of alpha,beta-acetylenic ketones by catalytic heterogeneous oxidation of alkynes

Covalent grafting of iron phthalocyanines onto silica affords active catalysts for selective oxidation of alkynes and propargylic alcohols to alpha, beta-acetylenic ketones, highly valuable precursors in the preparation of fine chemicals.     

费托合成:SiO_2和Al_2O_3负载的Co_2C催化剂的表征和评价

采用CO碳化SiO2和Al3O4负载的Co(NO3)2的方法制备了SiO2和Al3O4负载的Co2C催化剂,采用N2物理吸附、X射线衍射和H2-程序升温还原技术对催化剂进行了表征,并用于催化费托合成反应中.结果显示,需要较长碳化时间才可合成负载的Co2C催化剂;所制催化剂表现出CO加氢生成高碳醇的催化性能,其原因可能在于催化剂表面存在的金属Co物种使CO解离,表面Co物种有利于CO插入,从而导致醇的生成,但体相Co2C则不具有催化活性.     

Supported ruthenium hydride catalysts for direct conversion of alcohols to carboxylic acids using styrene oxide as oxidant

In the present work, the ability of two ruthenium hydride catalysts supported on multiwall carbon nanotubes, [Ru–H@EDT–MWCNT], and gold nanoparticles cored triazine dendrimer, [Ru–H@AuNPs–TD], in the direct conversion of alcohols to carboxylic acids via transfer hydrogenation using styrene oxide as oxidant is reported. Different alcohols were successfully converted to their corresponding carboxylic acids. The results showed that these two heterogeneous catalysts are more efficient than the homogeneous counterpart. In addition, the catalysts were reused several times.     

Copper-containing catalysts for the oxidative dehydrogenation of organic compounds

A method of doping magnesium aluminum hydrotalcites, which are precursors for oxidative dehydrogenation oxide catalysts of various compositions, with copper(II) was developed, and copper(II)-containing oxide catalyst samples were synthesized. The catalytic properties of these catalysts were studied in the oxidative dehydrogenation of ethane, propane, and hexane. The conversion of ethane into ethylene on the copper-containing catalysts was established to proceed with high selectivities (90?C97%) and at low temperatures (400?C450°C).     

In situ Raman studies during sulfidation, and operando Raman-GC during ammoxidation reaction using nickel-containing catalysts: a valuable tool to identify the transformations of catalytic species

Ni-containing catalysts are investigated under reaction conditions for two different cases, during sulfidation, with Ni-Mo based catalysts, and during ammoxidation reaction, with the Ni-Nb catalysts. It is shown how Raman spectroscopy can follow some of the transformations of these catalysts upon different treatments. For the NiMo/Al(2)O(3)-SiO(2) system it was possible to identify some of the sulfided Mo species formed during the sulfidation of the oxide precursors, while for the bulk Ni-Nb oxide catalysts the simultaneous reaction-Raman results strongly suggest that the incipient interaction between niobium and nickel oxides at low Nb/Ni atomic ratios is directly related to catalytic activity, and that a larger size well-defined NiNb(2)O(6) mixed oxide phase is not active for this reaction. Moreover, the promotion by niobium doping appears to be limited to a moderate niobium loading. It was found that in situ and operando Raman are valuable techniques that allowed the identification of active Mo-S and Ni-Nb species under reaction conditions, and that are not stable under air atmospheres.     

Spectroscopic study of nickel hydroxyde,nickel carbonate-hexahydrate and nickel hydroxocarbonate

The electronic and IR-spectra of nickel hydroxocarbonate are investigated. Since the solid substance is amorphous these studies are the only source of information about the bonding mode of the hydroxo- and carbonate groups in it. The spectra of the hydroxocarbonate were compared with the spectra of the nickel hydroxide and the nickel carbonate-hexahydrate. Correlation analysis of the vibrational spectra was made. It was proved that the solid nickel hydroxocarbonate contains molecular groups which differ from those in solid nickel hydroxide and nickel carbonate and that hydroxocarbonate is an individual chemical compound whose structure is similar to the structure of nickel hydroxide and nickel carbonate-hexahydrate.     

Oxide supported platinum electrocatalysts for hydrogen and alcohol fuel cells

Efficient oxide supported electrocatalysts for hydrogen and alcohol fuel cells are developed. They are characterized by a low content of platinum, exhibit high activity in the oxidation of low-molecular alcohols and tolerance to the CO poisoning. It is shown that the application of catalysts developed (Pt/SnO₂-SbO _x ) enables one to raise the power of fuel cells operating on ethanol approximately by two times as compared with similar fuel cells with commercial PtRu/C catalysts.     

Niobium(V) oxide: a new and efficient catalyst for the transesterification of β-keto esters

Niobium(V) oxide is an efficient catalyst for the transesterification of β-keto esters with several kinds of alcohols, leading to good conversions. Moderate to good isolated product yields have been obtained at faster rates than those recently reported for various catalysts.     

多相催化剂的MOVS制备方法

介绍了非均匀相催化剂的ＭＯＶＳ制备方法，以该法制得的ＭｏＯ３催化剂在甲醇选择氧化制甲醛、ＣＯ加氢制高级和喹啉加氢脱氮中均显示出常规催化剂更为优异的催化性能，并探讨了ＭＯＶＳ催化剂的内在特性与催化性能的关系。