烯烃聚合钯催化剂研究进展

综述了烯烃聚合钯催化剂的研究进展,烯烃聚合钯催化剂的配体类型有膦配体、氮配体、碳配体、氧配体、氮-氧配体、膦-氧配体、氮-膦配体等。与齐格勒-纳塔催化剂和茂金属催化剂相比,烯烃聚合钯催化剂具有高催化活性、单活性中心和良好的分子剪裁性等优点,可在分子层次上实现烯烃聚合的分子设计与组装;与铁、钴、镍等后过渡金属催化剂相比,烯烃聚合钯催化剂具有反应条件较温和、催化活性和立体选择性较高的优势。     

高分子负载催化剂中金属流失的研究 Ⅱ．活性中心金属的影响

通过测定加氢反应后反应溶液中金属的溶出量,考察了高分子负载催化剂的稳定性,研究了活性中心金属的种类、价态及分散程度对催化剂稳定性的影响。实验表明,在聚苯乙烯苄基氨茴酸树脂载体上,不同金属物种的催化剂稳定性次序为:Pd混合价态钯>二价钯。随着载体表面钯分散度的增大,钯盐中配体En值的减小,溶剂极性的减弱,钯的流失量也呈下降趋势。     

钯(0)/离子交换树脂对有机锡试剂和有机卤化物偶联反应的催化性能和结构表征

制备了强碱阴离子交换树脂（Ｐ－－ＣＨ２＾＋（ＣＨ３）３ＯＨ＾－，Ｄ７１７）负载钯（０）催化剂，发现它对有机锡试剂和有机卤化物的偶联反应有很高的催化活性，分离容易，可重复使用。起催化作用的是金属态钯。ＸＰＳ等实验结果表明，在催化剂中钯作为桥将功能基－Ｎ＾＋（ＣＨ３）３与ＯＨ＾－联结起来。催化剂中的钯可以看作是两配位的和配位不饱和的，经过氧化加成、金属交换、还原消除过程完成催化反应。     

钯（0）／离子交换树脂对有机锡试剂和有机卤化物偶联反应的催化性能和结构表征

制备了强碱性阴离子交换树脂（）负载钯（０）催化剂，发现它对有机锡试剂和有机卤化物的偶联反应有很高的催化活性，分离容易，可重复使用．起催化作用的是金属态把．ＸＰＳ等实验结果表明，在催化剂中钯作为桥将功能基－Ｎ（ＣＨ３）３与ＯＨ－联结起来．催化剂中的把可以看作是两配位的和配位不饱和的，经过氧化加成、金属交换、还原消除过程完成催化反应．     

马来酸-苯乙烯共聚物-钯络合物催化剂在加氢反应中的变化及钯的回收利用

马来酸-苯乙烯共聚物-钯络合物在催化加氢过程中,络合在高分子配体上的钯离子易被还原为Pd(0),而部分地脱落下来,这可从XPS及电镜分析证实。催化活性中心可能是高分子络合(或隔离保护)的Pd(0)微粒。本文研究了高分子钯催化剂在硝基苯加氢过程中,钯的用量范围,溶剂对催化活性的影响,催化剂的回收与其活性及金属钯的回收与再利用。此外还测定了硝基苯催化加氢的活化能。     

溶剂化金属原子浸渍法制备纳米粒子Pd/γ-Al2O3低温CO氧化催化剂

用溶剂化金属原子浸渍法制备了不同钯含量的高分散Pd/γ-Al2O3催化剂,XRD和化学吸收测定结果表明,随着钯含量的增加,钯颗粒度增大,但直径都在2.0～6.0nm范围内.XPS研究表明,钯处于金属态.Pd/γ-Al2O3在较低温度下就显示出CO氧化催化活性,在453K时CO的转化率都可达到1∞%,随着钯粒度减小,催化活性升高,钯颗粒度为2.1nm的Pd/γ-Al2O3催化剂活性最高     

钯前驱体对汽车尾气处理Pd/Ce_(0.67)Zr_(0.33)O_2催化剂催化性能的影响(英文)

分别以Pd(NO3)2,Pd(NH3)4(NO3)2和H2Pd Cl4为钯前驱体制备了Pd/Ce0.67Zr0.33O2(CZ)催化剂.以硝酸钯为钯前驱体制得的Pd/CZ(NO)催化剂具有较高的储氧量,存在较多的小的钯簇,其钯与载体间相互作用较强,因此在三种新鲜催化剂中对HC和CO的消除表现出了最好的催化活性.以硝酸四氨钯为钯前驱体制得的Pd/CZ(NH)催化剂具有较高的钯分散度,存在较多的大的钯簇,同时存在金属态和氧化态的钯,从而对NO和NO2的消除表现出了较好的催化活性.以氯钯酸为钯前驱体制得的Pd/CZ(Cl)催化剂由于钯分散度较小,钯与载体间作用较弱,存在的CeOCl抑制了氧空穴的生成,因此对各种反应物的催化活性都较低.但Pd/CZ(Cl)催化剂表现出了较好的热稳定性,这是由于老化处理消除了残余的氯物种并且促进了钯与载体间的作用.     

溶剂化金属原子浸渍法制备纳米粒子Pd/γ-Al2O3低温CO氧化催化剂

用溶剂化金属原子浸渍法制备了不同钯含量的高分散Pd/γ-Al2O3催化剂,XRD和化学吸收测定结果表明,随着钯含量的增加,钯颗粒度增大,但直径都在2.0～6.0nm范围内.XPS研究表明,钯处于金属态.Pd/γ-Al2O3在较低温度下就显示出CO氧化催化活性,在453K时CO的转化率都可达到1∞%,随着钯粒度减小,催化活性升高,钯颗粒度为2.1nm的Pd/γ-Al2O3催化剂活性最高     

取代邻硝基苯酚的聚合物负载催化剂还原反应

制备了聚合物硼氢阴离子交换树脂（BER）、活性碳钯（Pd／C）和聚合物负载金属钯（Pd／D411）等催化剂，对各种取代的邻硝基苯酚进行了催化氢化还原反应。比较了上述三种催化剂对各种底物的催化活性的影响。研究结果表明：当邻硝基苯酚的苯环上取代基不同或取代基的位置不同时，它们被还原的难易程度不同。另外，催化剂载体对催化剂的性能也有很大影响。     

天然高分子负载型钯催化剂的表征及在催化苯乙烯氢酯基化反应中的重复使用

用SiO2担载壳聚糖（简写为CS），再负载PdCl2，制得催化剂SiO2-CS-PdCl2，其在苯乙烯及其衍生物的氢酯基化反应中表现出了较高的催化活性和选择性。XPS和TEM数据表明，催化剂的活性组分颗粒以纳米尺寸均匀地分布在载体表面，而且载体CS对金属钯有明显的配位作用。在反应体系中加入少量对苯醌，可防止钯聚集成钯黑沉淀而使催化剂失活，改善催化剂的重复使用效果。     

负载型Heck反应催化剂的研究进展

Heck反应是一类重要的C-C偶联反应,传统的均相Heck反应催化剂存在分离和回收困难等问题;近年来负载型Heck反应催化剂的研究引起了人们的广泛关注.本文综述了钯基和非钯基负载型Heck反应催化剂的研究进展,评述了不同载体上催化活性组分对Heck反应的特点,并展望了其发展趋势.     

Monodispersed Pd-Ni nanoparticles: composition control synthesis and catalytic properties in the Miyaura-Suzuki reaction

We have successfully prepared a series of magnetically separable "quasi-homogeneous" Pd-Ni nanoalloy catalysts with tunable composition in a one-pot wet chemical route. We have evaluated the catalytic activity of these Pd-Ni alloy catalysts with different compositions through the Miyaura-Suzuki coupling reaction. These palladium/non-noble metal alloy catalysts show better catalytic activity than an equal amount of palladium nanoparticles. Furthermore, these catalysts exhibited excellent performance in superparamagnetism owing to its great advantage for reducing the usage of noble metal.     

氧化镁的结构与甲烷氧化偶联催化性能

制法不同的ＭｇＯ对甲烷氧化偶联的催化性能相差悬殊，比表面积、ＸＲＤ、ＸＰＳ测试结果表明，在较低的反应温度范围内，比表面积大，则晶格畸变率大、晶粒度小，表面未饱和的配位氧量高的ＭｇＯ有较好的催化性能。     

Effect of addition of iron on morphology and catalytic activity of PdCu nanoalloy thin film as catalyst in Sonogashira coupling reaction

Palladium‐supported catalysts are complex assemblies with a challenging preparation. Minor changes in their preparation conditions can affect the activity, selectivity and lifetime of these catalysts. PdCuFe nanoparticle (NP) thin films were supported on reduced graphene oxide (RGO) by the reduction of the organometallic complex [PdCl_2‌(cod)] (cod = cis ,cis ‐1,5‐cyclooctadiene), and [Cu(acac)₂] and [Fe(acac)₃] (acac = acetylacetonate) complexes at a toluene–water interface. We have investigated the application of the liquid–liquid interface method for preparing ultrathin films of catalysts and have evaluated the catalytic activity of the prepared NPs for the Sonogashira coupling reaction in micelle media. Also, we have investigated the effect of the addition of iron on the morphology, size and catalytic activity of PdCu/RGO NPs. Our study shows that both of the prepared catalysts (PdCu/RGO and PdCuFe/RGO) are efficient and recoverable catalysts for the Sonogashira carbon–carbon coupling reaction. This method has advantages compared to other routes, such as short reaction times, high to excellent yields, facile and low‐cost method for the preparation of the catalysts, and easy separation and reusability of the catalysts.     

One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones Catalyzed by Acidic Ionic Liquids Under Solvent-Free Conditions

The acidic ionic liquids were new catalysts for the one-pot Biginelli reaction coupling of aldehyde, 1,3-dicarbonyl compound, and urea to afford the corresponding dihydropyrimidinones in good yields under solvent-free conditions. The catalysts could be recycled and reused five times without a noticeable decrease in catalytic activity.     

钙钛矿型氧化物催化剂SrTiO3的甲烷氧化偶联反应性能的研究

碱土元素氧化物是一类具有较好催化活性和选择性的甲烷氧化偶联(OCM)催化剂[1,2]。Filkova[3]等研究了不同的碱土金属氧化物促进的Nd2O3催化剂的OCM催化性能,发现在所有碱土金属氧化物-Nd2O3催化剂中,SrO-Nd2O3催化剂具有最高的生成C2烃的选择性,这可能因为SrO较强的碱性以及Sr     

SBA‐15@ABA-M (M = Cu,Ni and Pd): Three efficient,novel and green catalysts for oxidative coupling of thiols under mild reaction conditions

In the present study, oxidative coupling of thiols was carried out using immobilized Cu, Ni and Pd complexes on SBA-15 mesostructured as novel and green heterogeneous catalysts under mild reaction conditions. These supported complexes were characterized by FT-IR, XRD, TEM, TGA, EDX, ICP and BET techniques. These nanohybrid robust catalysts have outstanding advantages such as facile synthesis, use of green medium, high surface area, easy separation and workup, excellent reused for several consecutive cycles without noticeable change in its catalytic activity, and short reaction time.     

Heck反应最新研究进展

Heck反应是一类重要的卤代芳烃烯基化、形成新的C—C键的合成反应, 近几年来一直是催化化学和有机化学的研究热点. 总结了最近几年来国内外Heck反应新型催化体系、不对称Heck反应、Heck反应在有机合成中的最新应用等重要研究成果, 希望引起同行对Heck反应的关注.     

Study of methanol and isobutanol coupling over acid catalysts

The coupling of methanol and isobutanol was carried out over selected acid catalysts. An amorphous silica-alumina, a zeolite and aluminas were tested as catalysts of the coupling. The correlation between the catalysts acidity and their activity and selectivity was studied. The catalytic tests were carried out in a fixed-bed flow microreactor working on line with a gas-chromatograph. The acidic properties of the catalysts were followed by IR studies of pyridine adsorption. The results obtained proved that the strength and the concentration of acid sites on the catalysts surface effected the alcohols conversion to ethers. It was found that the undesirable dehydration of isobutanol to isobutene was catalyzed by stronger acid sites than those required for the etherification reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

The first N-heterocyclic carbene-based nickel catalyst for C-S coupling

We have developed the first N-heterocyclic carbene (NHC)-based transition metal catalysts for C-S coupling reactions. Ni-NHC catalysts showed good to excellent activities toward various aryl halides in C-S coupling reactions. The catalytic activities were greatly affected by the electronic and steric properties of the NHC ligands. The new catalysts were inexpensive, easy to synthesize, and environmentally friendly. They could be excellent candidates to replace Pd-organophosphanes for C-S coupling catalysis.