高分子分散钯催化剂催化对硝基苯酚加氢反应的研究

制备了多种商品化的离子交换树脂和螯合树脂分散钯催化剂,考察了它们对对硝基苯酚加氢反应的催化活性。结果表明这些催化剂对对硝基苯酚的加氢反应有较高的活性,其中阴离子交换树脂和H型阳离子交换树脂分散钯催化剂活性最高。催化剂加氢活性与反应进程有关。     

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。     

高分子膦-钯络合催化剂的氢化催化活性和稳定性的考察

本文报道高分子膦-钯络合催化剂的合成及对催化剂催化加氢的活性、稳定性进行考察的结果。与文献对比表明,高分子膦-钯络合催化剂具有良好的稳定性和催化活性,膦化物不失为一类优良的配位体。     

含氨基酸侧链的有机硅高分子催化剂——Ⅸ.聚γ-(甘-色二肽基)丙基硅氧烷钯催化剂的合成、加氢活性及结构表征

本文报道了不同N/Pd摩尔比的聚γ-(甘-色二肽基)丙基硅氧烷钯催化剂的合成及对烯烃和硝基苯的加氢活性.催化剂的结构表征说明,其活性中心的组成可能是氨基酸配体的羧基与PdCl_2的络合.这种催化剂对丙烯腈和苯乙烯有较高的加氢活性,而对硝基苯的氢化没有催化活性.并研究了溶剂和温度对加氢活性的影响.     

含氨基酸侧链的有机硅高分子催化剂 ⅩⅤ.γ-(L-酪氨酰胺基)丙基硅氧烷钯催化剂的合成加氢活性及其结构表征

本文报导了四种不同N/Pd摩尔比的聚γ-(L-酪氨酰胺基)丙基硅氧烷钯催化剂的合成及其催化加氢活性,这类催化剂与聚γ-((L-酷氨酸)丙基硅氧烷钯催化剂相比较,虽然均具有类似的N→Pd配位的活性中心组成,但它们对底物的加氢活性则明显不同,前者对丙烯腈、丙烯酸、环己烯和1-癸烯的催化活性比后者高,对苯乙烯则相反。N/Pd摩尔比、反应温度、溶剂以及体系的pH值对催化活性的影响,两者的情况大致相同,标题催化剂对衣康酸的催化加氢,产物的光学纯度为30％。     

高分子负载钯催化剂中载体主链在催化加氢反应中的作用

报导几种以聚2,6-二甲基1,4-苯醚(PPO)和聚砜(PSu)为主链的负载钯催化剂对1-辛烯和环戊二烯在温和条件下的催化加氢活性与选择性。官能团化的PPO负载钯催化剂对1-辛烯的催化加氢活性大于官能团化的PSu负载钯催化剂的活性,但前者在加氢过程中的活性下降比后者快得多;官能团化的PPO负载钯催化剂在1-辛烯加氢过程中活性很快下降的原因与其强的异构化性能和异构化产物有关。相同配体的两种负载钯催化剂对环戊二烯的催化加氢表现在活性上,PPO低于PSu,而选择性PPO高于PSu。表明除了按预计与钯直接配位的配体外,载体主链结构对负载钯催化剂的加氢性能也有显著影响。     

含氨基酸侧链的有机硅高分子催化剂——Ⅲ.聚γ—(丝氨酸基)丙基硅氧烷钯催化剂的合成、加氢活性及XPS研究

本文报导7四种不同-COOH/Pd摩尔比的聚γ—(丝氨酸基)丙基硅氧烷钯催化剂的合成及其XPS结构表征。加氢实验结果表明,这种催化剂对所用底物有高的催化活性,当-COOH/Pd比、内3.76:1时,对苯乙烯的起始加氢速度达2558.9mLH_2/min.mmolPd,并讨论了不同溶剂和温度对催化剂活性的影响。     

铈对低负载Pd/Al2O3催化剂加氢丙烯腈的改性效应

钯基催化剂对烯烃及烯烃类衍生物有很好的加氢活性。但钯催化剂价格昂贵,单一的钯容易中毒失活,研究表明：掺入稀土氧化物能够提高钯催化剂在载体上的分散度,增大其氧化及氢化活性,提高催化剂的寿命及稳定性。但稀土助剂对双键选择性加氢影响的研究却很少有报     

PVP负载Pd—Co催化剂催化六氯苯的加氢脱氯

研究了温和条件下钯催化剂催化六氯苯加氢脱氢反应。结果表明,ＰｄＣｌ２催化活性不高,而ＰＶＰ负载ＰｄＣｌ２活性较高,ＰＶＰ负载Ｐｄ－Ｃｏ催化剂具有双金属协同效应,提高了催化活性。５５℃下,该催化剂在Ｃｏ／Ｐｄ摩尔比为０．５时表现出最高的催化活性。     

PVP负载Pd-Co催化剂催化六氯苯的加氢脱氯

研究了温和条件下钯催化剂催化六氯苯加氢脱氢反应． 结果表明, Ｐｄ Ｃｌ２ 催化活性不高,而 Ｐ Ｖ Ｐ 负载 Ｐｄ Ｃｌ２ 活性较高． Ｐ Ｖ Ｐ 负载 Ｐｄ Ｃｏ 催化剂具有双金属协同效应,提高了催化活性．５５ ℃下,该催化剂在 Ｃｏ／ Ｐｄ 摩尔比为０５ 时表现出最高的催化活性．     

Comparison of new microemulsion prepared "Pt-in-Ceria" catalyst with conventional "Pt-on-Ceria" catalyst for water-gas shift reaction

New "Pt-in-CeO(2)" catalyst prepared by microemulsion method is shown to give higher activity for a water-gas shift reaction but with no formation of CH(4), the side product from hydrogenation of carbon oxides using a hydrogen-rich reformate as compared to conventional "Pt-on-CeO(2)" catalysts. Detailed characterization by DRIFT analysis and temperature programmed reduction presented in this work clearly suggest the ceria coverage on Pt inhibits the metal from forming a strong CO adsorption.     

In situ hydrogenation of terminal halogen in poly(methyl methacrylate) by ruthenium-catalyzed living radical polymerization: direct transformation of "polymerization catalyst" into "hydrogenation catalyst"

An in situ, selective, and quantitative hydrogenation of the terminal chlorine (alpha-haloester) in living PMMA-Cl into PMMA-H was achieved via direct transformation of a "polymerization catalyst" into a "hydrogenation catalyst" in the Ru(II)-catalyzed living radical polymerization, where the polymerization mixture of MMA was directly treated in situ with K2CO3 as a base and 2-propanol as a hydrogen donor. The reaction terminated the polymerization and, more importantly, the terminal chlorine was quantitatively hydrogenated, as confirmed by SEC, 1H NMR, and MALDI-TOF MS.     

聚γ—（乙二胺基）丙基硅氧烷负载的钯,镍双金属催化剂研究

本工作制取了聚γ-(乙二胺基)丙基硅氧烷〔SiO_2 Si-O-Si-(CH_2)_3NHCH_2CH_2NH_2〕负载的钯、镍双金属催化剂及相应的单金属催化剂。XPS测定表明,载体中的N与Pd~0、PdCl_2、NiCl_2之间产生络合。文中比较了双金属催化剂对癸烯-1、丙烯酸、环己烯、苯乙烯和硝基苯的加氢活性,研究了双金属催化剂,单金属催化剂及混合催化剂对环己烯的加氢活性,讨论了温度对双金属催化剂催化活性的影响。     

硼掺杂还原态氧化石墨烯催化剂的制备及其蒽催化加氢性能的研究

制备了一系列硼掺杂的还原氧化态石墨烯催化剂并应用于蒽加氢反应。结果表明，随着催化剂处理温度的升高，催化剂中有序碳结构会发生变化，硼会取代材料骨架中的碳，进而影响蒽和氢气的吸附活化。经硼改性后，催化剂对蒽加氢反应表现出了很高的加氢活性，蒽的最高转化率可达97%，深度加氢产物八氢蒽的最高选择性可达19%。     

PROPERTIES OF HIGHLY DISPERSED PALLADIUM CATALYSTS ON POLY N—VINYL—2—PYRROLIDONE

Four kinds of palladium catalysts dispersed on poly-N-vinyl-2-pyrrolidone were prepared by using CH3OH-NaOH,NaBH4,H2O or CH3OH-H2O as the reducing agent in the process of catalyst preparation. The catalysts were characterized by XPS,TEM,XRD and used for the hydrogenation of methyl acrylate.It was found that the valence state of palladium and distribution of palladium particles as well as the hydrogenation rate were greatly affected by the reducing agent.The best evenly dispersed palladium catalyst showing high hydrogenation activity was prepared using CH3OH-NaOH as the reducing agent.     

Identification of catalyst surface species during asymmetric platinum-catalysed hydrogenation in a "supercritical" solvent

In situ attenuated total reflection infrared spectroscopy studies during the enantioselective hydrogenation of ethyl pyruvate in "supercritical" ethane over a chirally modified Pt/Al(2)O(3) catalyst show the preferential adsorption of ethyl pyruvate as cis-conformer and indicate a hydrogen bond interaction of this species with the co-adsorbed modifier cinchonidine.     

A colloid "digesting" route to novel, thermally stable high surface area ZrO2 and Pd/ZrO2 catalytic materials

Zirconia having high thermal stability and high surface area (up to 160 m(2)/g at 700 degrees C) has been prepared by a colloidal "digesting" process. This material having demonstrated high surface areas at elevated temperatures was then applied as a catalyst support. A Pd colloid with diameter of approximately 12 nm has been successfully deposited on the high surface area zirconia material. All systems have been well characterized by TEM, X-ray diffraction, N2 adsorption isotherms, FTIR, elemental analysis and dynamic light scattering techniques. The colloidal Pd particles have been found homogeneously well dispersed in the hydrous zirconia matrix without aggregation. The Pd/ZrO2 catalysts have been screened for cyclohexene and 1-hexene hydrogenation activity and it was found that the catalyst is extremely active.     

Highly chemoselective hydrogenation of crotonaldehyde over Ag-In/SBA-15 fabricated by a modified "two solvents" strategy

In the challenging crotonaldehyde hydrogenation to crotyl alcohol, an Ag-In/SBA-15 catalyst fabricated by a modified "two solvents" strategy shows an unprecedentedly high yield of 86% at a selectivity of 87%, which exceeds the best results on Pt-, Au- and other Ag-based heterogeneous catalysts reported so far.     

NiFe双金属催化剂用于月桂酸甲酯加氢的研究

负载型Ni Fe/γ-Al₂O₃双金属催化剂的物理化学性质明显受还原温度的影响,进而影响月桂酸甲酯的加氢活性和产物选择性。金属Ni活性中心主要促进脱羰/脱羧(DOC)反应,Fe的加入能促进月桂酸甲酯发生加氢脱氧反应,促进C₁₂烷烃化合物生成。H₂-TPR、XRD、H₂-TPD和BET结果表明,高的还原温度有利于金属或合金活性中心形成,NiFe双金属催化剂的加氢活性取决于金属Ni、Fe和NiFe合金的含量;NiFe双金属催化剂吸附与活化H₂分子的能力明显受还原温度的影响。在研究的温度范围内,Ni活性中心具有优异的加氢和裂解性能,Fe物种的引入能有效抑制裂解性能。双金属催化剂的加氢活性顺序:NF420>NF360>NF450>NF300,在420℃下经H₂还原制得的NF420催化剂具有最佳的月桂酸甲酯加氢性能,在反应温度为380℃时,月桂酸甲酯加氢转化率和烷烃化合物选择性分别高达93.3%和90.0%。