CO2在Cu-Pd/MoO3-SiO2催化剂上的吸附与表面反应

用表面反应改性法制备了ＭｏＯ３－ＳｉＯ２表面复合物，用等体积浸渍法制备了ＭｏＯ３－ＳｉＯ２担载Ｃｕ－Ｐｄ金属催化剂，用ＩＲ和ＴＰＤ研究了Ｃ类其上的吸附，考察了ＣＯ２吸附产生ＣＯ和Ｏ的ＴＰＤ－ＭＳ结果，讨论了ＣＯ２在Ｃｕ－Ｐｄ／ＭｏＯ３－ＳｉＯ２上的表面反应机理。结果表明：ＣＯ２在催化剂上具有良好的化学吸附性能，形成线式吸附态、剪式吸附态和卧式吸附态；ＣＯ２卧式吸附态具有良好的表面反应活性，一定温度     

TiO2调变对MoO3／γ—Al2O3和CoO—MoO3／γ—Al2O3催化性能的影响

采用气相流动吸附法制备ＴｉＯ２／γ－Ａｌ２Ｏ３复合载体，用浸渍法其担载一定量的ＭｏＯ３或ＣｏＯ－ＭｏＯ３。用ＸＲＤ、ＬＲＳ和ＴＰＲ等技术，考察了Ｍｏ或Ｃｏ－Ｍｏ催化剂的表面结构和还原性能，并有和中压固定床反应装置测定催化剂的噻吩加氢脱硫和环己烯加氢的活性。     

CO2在Cu—Ni／MnO3—SiO2催化剂上的吸附与反应

采用表面反应改性法制备了ＭｏＯ３－ＳｉＯ２（ＭｏＳｉＯ）表面复合物,用等体积浸渍法制备了Ｍｏ－ＳｉＯ担载的Ｃｕ－Ｎｉ双金属催化剂。利用ＩＲ和ＴＰＤ研究了ＣＯ２在催化剂表面上的吸附性能,并讨论了ＣＯ２在Ｃｕ－Ｎｉ／ＭｏＳｉＯ上的表面反应机理。结果表明,ＣＯ２在上述催化剂上有良好的化学吸附性能,形成线式吸附态、剪式吸附态和卧式吸附态;ＣＯ２卧式吸附态具有良好的表面反应活性,在一定温度下可解离为吸附的Ｃ     

CO_2在Cu-Ni-Mo O_3-SiO_2催化剂上的吸附与反应

采用表面反应改性法制备了ＭｏＯ３－ＳｉＯ２（ＭｏＳｉＯ）表面复合物,用等体积浸渍法制备了ＭｏＳｉＯ担载的Ｃｕ－Ｎｉ双金属催化剂。利用ＩＲ和ＴＰＤ研究了ＣＯ２在催化剂表面上的吸附性能,并讨论了ＣＯ２在Ｃｕ－ＮｉＭｏＳｉＯ上的表面反应机理。结果表明,ＣＯ２在上述催化剂上有良好的化学吸附性能,形成线式吸附态、剪式吸附态和卧式吸附态;ＣＯ２卧式吸附态具有良好的表面反应活性,在一定温度下可解离为吸附的ＣＯ和Ｏ。这种新生态Ｏ具有良好的选择氧化性能     

La2O3对Ni-Mo/γ-Al2O3催化剂CO和CO2甲烷化的影响

采用浸渍法制备了一系列Ｎｉ－Ｍｏ－Ｌａ／γ－Ａｌ２Ｏ３催化剂并测定了催化剂的ＣＯ和ＣＯ２甲 化活性采用ＴＥＭ,ＸＰＳ和ＣＯ化学吸附等手段研究了表面性质。结果表明,Ｌａ２Ｏ３的咖入提高了Ｎｉ－Ｍｏ／γ／Ａｌ２Ｏ３催化剂的ＣＯ和ＣＯ２甲烷化活性,增加了催化剂中Ｎｉ的分散度,活性表面积及催化剂表面Ｎｉ原子的浓度,降低了电子结合能。     

Co-Mo/TiO2和Co-Mo/γ-Al2O3加氢脱硫催化剂的研究

本文考察了ＣｏＭｏ／ＴｉＯ２和ＣｏＭｏ／γ－Ａｌ２Ｏ３催化剂的加氢脱硫性能及表面结构变化和处理条件对其活性的影响，担体ＴｉＯ２（Ａ）和ＴｉＯ２（Ｂ）分别采用ＴｉＯＳＯ４水解法制备，结果表明，催化剂的活性顺序为ＣｏＭｏ／ＴｉＯ２（Ａ）＞ＣｏＭｏ／ＴｉＯ２（Ｂ）＞ＣｏＭｏ／γ－Ａｌ２Ｏ３，催化剂的预处理条件对催化剂的加氢脱硫和加氢活性有很大影响，ＴｉＯ２担体上Ｍｏ物种主要以八面体配位构型存在，Ｍｏ＾－     

炭担载的Mo和CoMo加氢脱硫催化剂

用仲钼酸铵和酸钴水溶液浸渍方法将ＭｏＯ３和ＣｏＯ担载在少在性炭担体上，制成Ｍｏ／Ｃ和ＣｏＭｏ／Ｃ催化剂。运用ＤＴＡ，ＸＰＳ，ＦＴ－ＬＲＳ等手段考察了ＭｎＯ３在活性炭担体表面的分散状态及Ｈ２还原能力随ＭｏＯ３含量的变化，并在中压固定床反应装置上测定了催化剂的噻吩加氢脱硫和环己烯加氢反应活性。     

Mo助剂对Rh／SiO_2催化剂上甲醇吸附性能的影响

用原位红外光谱和程序升温还原技术考察了甲醇在Ｒｈ－Ｍｏ／ＳｉＯ入催化剂上的吸附和还原性能．红外结果表明，甲醇在ＳｉＯ２上主要以分子形式吸附．Ｒｈ／ＳｉＯ２和Ｒｈ－Ｍｏ／ＳｉＯ２在室温下对甲醇分解就有活性，分解生成的ＣＯ以线式和桥式吸附态存在．在５７３Ｋ下用甲醇处理后，Ｒｈ／ＳｉＯ２上ＣＯ线式和桥式谱带分别位于２０５０和１９０７ｃｍ－１，而Ｒｈ－Ｍｏ（１：１）／ＳｉＯ２上线式ＣＯ位于２０３６ｃｍ－１，桥式ＣＯ强度很弱．Ｍｏ的添加有可能覆盖部分Ｒｈ金属表面的吸附中心，从而降低ＣＯ吸附谱带的强度，同时使桥式ＣＯ的形成变得困难．随Ｍｏ助剂量的增加，Ｒｈ的还原温度升高，而Ｍｏ的还原温度降低．由此推断，Ｒｈ～Ｍｏ／ＳｉＯ２催化剂上的Ｒｈ可能有三种存在形式：氯化物、低温还原氧化物和高温还原氧化物．     

TiO_2调变对MoO_3/γ-Al_2O_3和CoO-MoO_3/γ-Al_2O_3表面结构及还原性能的影响

采用气相流动吸附法制ＴｉＯ２／γ－Ａｌ２Ｏ３，复合载体，浸渍法担载一定量ＭｏＯ３或ＣｏＯ－ＭｏＯ３，用ＸＲＤ，ＬＲＳ和ＴＰＲ等技术考察了Ｍｏ或Ｃｏ－Ｍｏ催化剂的表面结构和还原性能。结果表明，覆盖在γ－Ａｌ２Ｏ３上的ＴｉＯ２能减弱ＭｏＯ３与γ－Ａｌ２Ｏ３之间的相互作用，明显改善Ｍｏ催化剂的表面结构，促进ＭｏＯ３的还原。适量ＣｏＯ助剂的加入能促进ＭｏＯ３在载体表面的分散。     

硫化态NiMoK／Al2O3变换催化剂对水的吸附性能

硫化态ＮｉＭｏＫ／Ａｌ＿２Ｏ＿３变换催化剂对水的吸附性能李利民，郭益群，王贵昌，王文祥（郑州大学化学系郑州４５００５２）关键词水煤气变换催化剂，硫化，水吸附，脉冲气相色谱ＣＯ（Ｎｉ）ＭｏＫ／Ａｌ＿２Ｏ＿３型催化剂用于变换反应时需首先进行硫化，硫化温度...     

Synthesis and reactivity of allyl nickel(II) N‐heterocyclic carbene enolate complexes

Two new N‐heterocyclic carbene enolate nickel(II) allyl complexes have been prepared and their activity towards ethylene polymerization was investigated. It was found that in the presence of diethyl zinc, the carbene enolate complex bearing a nitro substituent produces highly linear polyethylene of modest molecular weight and high polydispersity. The influence of the reaction parameters on catalytic activity and the characteristics of the resulting polymer were investigated through systematic variation of the time, temperature, and diethyl zinc concentration. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:3637–3647, 2007     

Comparative characterization of MgCl2/ethyl benzoate/TiCl4 and MgCl2/2,2,6,6 tetramethylpiperidine/TiCl4 Ziegler-Natta precatalysts

In this article we present the results of the preparation and characterization of two Ziegler–Natta precatalysts: MgCl₂/Ethyl benzoate (EB)/TiCl₄ and MgCl₂/2,2,6,6 tetramethylpiperidine (TMPiP)/TiCl₄ by means of FTIR, X-ray diffraction, SEM, BET surface area measurements, and other techniques applied at different steps of their preparation procedures. The precatalysts were prepared by impregnating with TiCl₄ a given amount of MgCl₂, which was previously ball-milled with the electron donor chosen. Prior to impregnation, the ball-milled material presented different surface compounds depending on the electron donor used: [(MgCl₂)₂] · 2EB, MgCl₂ · EB, or a salt of the amine. The solid milled with EB is more homogeneous than the one milled with the TMPiP. Titanium is better retained in the solid milled with EB. This precatalyst has better morphological properties and larger BET surface area. By means of FTIR, we found evidences that an adequate surface structure for the formation of stereospecific sites in MgCl₂/TMPiP/TiCl₄ was formed. © 1994 John Wiley & Sons, Inc.     

Structure of Pd/SiO2 sol-gel and impregnated catalysts

Palladium catalysts were prepared by sol-gel and impregnation techniques both in acid and basic media. The sol-gel catalysts resulted in larger PdO crystallites than the impregnated catalysts. In both preparation methods, an acid medium promoted the formation of small metal crystallites which provided catalytic activity. A stronger metal-support interaction was found in sol-gel catalysts synthesized from a square planar palladium complex. Deactivation results in phenylacetylene hydrogenation have been attributed to palladium hydrate formation or to deposition of carbonaceous compounds. The preparation mode determined the contribution of each deactivating reaction.     

Developments in Titanium-Based Alkali and Alkaline Earth Metal Oxide Catalysts for Sustainable Biodiesel Production: A Review

Biodiesel represents a biodegradable, environmentally friendly, and renewable alternative to fossil fuels. Despite more than three decades of research, significant obstacles still hinder the widespread production of biodiesel. This current review elucidates both the potential and the existing challenges associated with homogeneous and heterogeneous catalysts in catalyzing biodiesel production, with a particular focus on alkali analogues, alkaline earth metal oxides, and titania-based catalysts. In particular, a comprehensive analysis is presented concerning alkali and alkaline earth-based titania (TiO₂) catalysts. Among these, the alkaline earth metal oxides, including lithium, calcium, and strontium when combined with titanium-based catalysts, exhibit superior catalytic activity compared to other metal oxides, owing to their heightened basicity. Consequently, this review offers a thorough and up-to-date insight into the potential of titania-based heterogeneous catalysts for advancing biodiesel production.     

高分子负载催化剂的设计、合成及其在有机合成反应中的应用*

发展可回收和可重复利用的催化剂是过去几十年研究的一个热点,在这篇综述中,我们简要介绍了高分子负载催化剂的设计和合成策略以及这些催化剂在各种不同有机反应中的深入应用。在很多情况下,这一策略显示了它在产物的分离以及昂贵的催化剂的回收和再利用上的显著优点。与没有负载的同类催化剂相比,高分子负载的催化剂可以保持了同样的催化活性。另一方面,发展可控结构,尺寸,外观以及可溶性的线性聚合或树枝状的手性催化剂对于它们在有机合成中的应用都具有非常重要的意义。通过有机,高分子,以及材料化学家的共同努力,这一方法在跨学科间取得了很大的进展,这一发展对于决定载体的选择起到了很大的作用。因此,进一步发展高活性和高对映选择性的催化剂将仍然是这一领域的重要目标和挑战。     

The active species of the chromium (phillips type) catalysts for the polymerization of ethylene: A unifying approach

From literature data it is concluded that the rate of the reduction, alkylation, polymer chain growth, and chain transfer reactions of three chromium(II) and one chromium(III) surface species all increase with decreasing electron density at the chromium ion. This electron density has previously been measured by the IR shift of the stretching vibration of one CO molecule terminally adsorbed on these chromium ions. It is observed that the reduction half time decreases proportional to the increasing Lewis acidity and that the rate of the polymer chain growth reaction increases exponentially for three chromium surface species with increasing CO stretching vibration. Due to the large difference of the polymer chain growth rates for the two chromium (II) species (A_d and C_d), common in the normal Phillips catalyst, both contribute almost equally to the polymer product, although the A_d species outnumbers the C_d one by more than 3 to 1.     

有机金属烯烃配位聚合催化剂

有机金属烯烃配位聚合催化剂具有高催化活性和良好的分子剪裁性,通过调节催化剂的微结构,如配体的取代基?配位原子以及配位中心的电子与立体环境等,可以在分子层次上实现烯烃聚合物的分子设计与组装;实现聚合物物理性质的调控,从而得到各种具有新型功能和立体异构的聚合物。本文综述了金属烯烃聚合催化剂研究进展,并展望该领域的发展趋势。     

Comparison of a range of rhodium-based catalysts for the hydroformylation of selected alkenes

Four rhodium-based catalyst systems 1, 2, 3, and [Rh(OAc)₂]₂/PPh₃ have been used in the hydroformylation of 1-hexene, styrene and some phosphino-, amino- and amido-alkenes. In general the catalysts showed very similar reactivity and selectivity.     

烯烃聚合催化剂的研究进展

获得高性能聚烯烃材料是化学家们不断的追求。烯烃聚合催化剂的结构对其催化性能有重要影响,而聚烯烃的改性则能够改善聚合物实际应用中表面形貌、本体性能中存在的缺陷,如通过改性可增加聚合物韧性、降低聚合物表面的摩擦系数或提升表面能等。 本文系统总结了金属烯烃聚合催化剂研究进展,包括Ziegler-Natta催化剂、茂金属催化剂、非茂金属催化剂的结构及调控策略,探讨了位阻效应、双金属协同效应以及其他效应对催化效果的影响。     

Recent Advances in Continuous-Flow Enantioselective Catalysis

The increased demand for more efficient, safe, and green production in fine chemical and pharmaceutical industry calls for the development of continuous-flow manufacturing, and for chiral chemicals in particular, enantioselective catalytic processes. In recent years, this emerging direction has received considerable attention and has seen rapid progress. In most cases, catalytic enantioselective flow processes using homogeneous, heterogeneous, or enzymatic catalysts have shown significant advantages over the conventional batch mode, such as shortened reaction times, lower catalysts loadings, and higher selectivities in addition to the normal merits of non-enantioselective flow operations. In this Minireview, the advancements, key strategies, methods, and technologies developed the last six years as well as remaining challenges are summarized.