含第一过渡金属和钯的双金属高分子催化剂及其催化加氢性能的研究

高分子金属催化剂的性能,不仅与金属离子的种类有关,而且与高分子配体的结构有关。作者在以SiO_2负载的聚苯乙烯马来酸酐共聚物的苯胺氨解产物——钯单金属高分子催化剂(P—C_6H_5NH·Pd) 中引入少量的第一过渡金属离子,形成双金属高分子金属催化剂(P-C_6H_5NH·Pd·M)。研究结果表明,由于第一过渡金属离子的引入,使单金属高分子催化剂的催化加氢性能(活性、选择性和稳定性)得到了改善。而且发现,第一过渡金属离子的助催化作用与它的晶体场稳定化能(Crystal Field Stablization Energy,CFSE)有关。     

过渡金属硫化物催化剂催化加氢作用机理

负载型过渡金属(Co、Mo、Ni、W)硫化物催化剂广泛应用于石油炼制催化加氢过程.为了开发高性能的加氢催化剂,过渡金属硫化物催化剂催化活性相的结构与加氢脱硫性能的关系一直以来是催化研究的热点之一.本文从过渡金属硫化物催化剂的活性相结构和反应物在催化剂表面活性位上的吸附-催化反应机理两个方面阐述了过渡金属硫化物催化剂的催化作用研究进展,并对过渡金属硫化物催化剂催化机理研究存在的争议和未来的研究方向进行了分析.     

过渡金属硫化物催化剂催化加氢作用机理

负载型过渡金属(Co、Mo、Ni、W)硫化物催化剂广泛应用于石油炼制催化加氢过程。为了开发高性能的加氢催化剂,过渡金属硫化物催化剂催化活性相的结构与加氢脱硫性能的关系一直以来是催化研究的热点之一。本文从过渡金属硫化物催化剂的活性相结构和反应物在催化剂表面活性位上的吸附-催化反应机理两个方面阐述了过渡金属硫化物催化剂的催化作用研究进展,并对过渡金属硫化物催化剂催化机理研究存在的争议和未来的研究方向进行了分析。     

过渡金属硫化物催化剂催化加氢作用机理

负载型过渡金属(Co、Mo、Ni、W)硫化物催化剂广泛应用于石油炼制催化加氢过程.为了开发高性能的加氢催化剂,过渡金属硫化物催化剂催化活性相的结构与加氢脱硫性能的关系一直以来是催化研究的热点之一.本文从过渡金属硫化物催化剂的活性相结构和反应物在催化剂表面活性位上的吸附-催化反应机理两个方面阐述了过渡金属硫化物催化剂的催化作用研究进展,并对过渡金属硫化物催化剂催化机理研究存在的争议和未来的研究方向进行了分析.     

金属氧化物改性的Pd／D3520催化剂及其催化加氢活性的研究

改变金属和载体的种类可以改变高分子催化剂的活性。本文在Ｄ３５２０负载的Ｐｄ催化剂中添加ＳｎＣｌ２．２Ｈ２Ｉ．ＦｅＣｌ３．６Ｈ２Ｏ，Ｐｂ（ＯＨ）２，ＢｉＣｌ３，形成Ｄ３５２０负载的金属氧化物──钯催化剂。研究结果表明，ＳｎＯ２，Ｆｅ２Ｏ３的引入对原催化剂具有良好的助催化效果，其中Ｆｅ２Ｏ３的引入使原单位金属高分子催化剂对苯乙烯的催化加氢活性提高１１０％，ＰｂＯ，Ｂｉ２Ｏ３的引入使催化加氢活性大大降低     

有机高分子金属络合物催化剂——在加氢方面的应用

论述了各种带有氮、氧、磷等配位基团的可溶性和不溶性高分子与铑、钯、铂等贵金属配位后对氢化反应的催化作用。一般说有机高分子-金属络合物催化剂比相应的低分子催化剂催化活性、稳定性和选择性都高。     

金属有机化合物的结构、活性及其应用

金属有机化学是化学的一门分支学科,它起始于研究金属与有机配体结合的化学,无机化学偏重于M—O,M—N,金属与电负性较大的杂原子配位的化合物,有机化学则偏重于M—C,金属与碳成键的化合物,有时这两类配合方式难以截然分开,统称为金属有机化学或配位化学。有机化学工作者较多地应用这类化合物于合成有机化合物,无机化学工作者较多研究它们的结构和性质;物理化学从理论上研究它们的结构和性质之间的关联和规律。本文试图介绍金属有机化合物的结构、活性及应用的近况。七十年代以前,人们习惯于从已经合成出的金属有机分子模式去进行结构的推导。二茂铁的合成是带有偶然性的,更早的羰基金属的发现也同样是偶然性的,每次这类新的金属有机化合物的发现,都促进了人们去研究它们的结构,理论上去解释新类型金属有机化合物的结构或键型。     

苯甲酸甲酯促进茂金属催化剂催化SBS加氢反应研究

以苯甲酸甲酯为促进剂,用茂金属催化剂制备了活性丁苯嵌段共聚物(SBS)的选择性催化加氢产物,讨论了苯甲酸甲酯、SBS的数均分子量等因素在几种实验条件下对产物加氢度的影响.结果表明,每百克干胶使用0.15～0.3mmol Ti催化条件下,苯甲酸甲酯在特定添加方式下能较大程度地提高茂金属催化剂的活性.在不加入苯甲酸甲酯的情况下,Mn=6.5×104和Mn=5.5×104两种SBS基础胶加氢反应180min时加氢度均97.0%;加入酯以后,反应60～120min时,基础胶的加氢度≥98%;与已报道的研究结果相比,将加氢反应时间缩短了60～120min.在每百克干胶使用0.15～0.3mmolTi催化条件下,数均分子量的大小也对SBS基础胶的加氢度有影响,反应30min时,Mn=5.5×104的加氢度≥97%,Mn=6.5×104的加氢度90%;随着反应时间的延长,这种差距在逐渐缩小;反应180min时,两者已无明显差距,此时两种基础胶的加氢度都≥98%.对影响的加氢度的机理进行了解释.     

镍族金属团簇在催化加氢过程中的应用

Nanoparticles of precious metals play an important role in many heterogeneous catalytic reactions due to their excellent catalytic performance. As an idealized model, gas phase metal clusters have been extensively utilized to understand catalytic mechanisms at a molecular level. Here we provide an overview of our recent studies on H₂ dissociative chemisorption on nickel family clusters. The structure evolution and the stability of the metal clusters were first compared. H₂ dissociation on the clusters was then carefully addressed to understand the capability of metal clusters to break the H-H bond. Two key parameters, the dissociative chemisorption energy (ΔE_CE) and the H sequential desorption energy (ΔE_DE), were employed to characterize the catalytic activity of metal clusters. Our results show that both ΔE_CE and ΔE_DE decline significantly as the H coverage increases. Since the catalyst is in general covered entirely by H atoms and H₂ molecules in a typical hydrogenation process, and maintained at a pre-determined pressure of H₂ gas, we can rationally use the calculated ΔE_CE and ΔE_DE values at full H saturation to address the activity of metal clusters. Our results suggest that at full H coverage, each Pt atom is essentially capable of adsorbing 4 H atoms, while each Ni or Pd atom can only accommodate 2 H atoms. Considering the similar values of H desorption energies on Pt and Pd clusters, the higher average H capacity per Pt atom could probably lead to a faster reaction rate because more active H atoms are produced on the Pt catalyst particles in the hydrogenation process. Finally, the charge sensitivity of the key catalytic properties of Pt clusters for hydrogenation was systematically evaluated. The results show that the dissociation of H₂ and H desorption are strongly correlated to the charge state of the Pt clusters at low H coverage. However, at high H-capacities, both ΔE_CE and ΔE_DE fall into a narrow range, suggesting that the charge can be readily dispersed and that the Pt-H bonds average the interaction between clusters and H atoms. As a result, the H-capacities on charged clusters were found to be similar as the cluster size increased; in case of sufficiently large clusters, the reactivity of a fully saturated cluster was no longer sensitive to its charge state.     

吡啶-三唑金属配合物的合成及其在乙烯聚合反应中的催化性能

以苄氯、吡啶炔和叠氮化钠为原料,在铜(Ⅰ)催化下,通过Click反应制得新型配体1-苄基-4-邻吡啶基-1,2,3-三唑(1); 1分别与无水FeCl₂, CoCl₂或NiBr₂ ·DME反应合成了3个新型的吡啶基三唑金属配合物(2~4),其结构经¹H NMR, ¹³C NMR, IR和元素分析表征。考察了2~4对乙烯聚合反应的催化性能。结果表明：以甲基铝氧烷(MAO)为助催化剂, 4具有最高的催化活性,在温度为20 ℃, Al/Ni为2 500条件下,催化活性达8.8×10⁵ g·mol^-1·h^-1。     

Immobilization of Polymer-Stabilized Noble Metal Colloids and Their Catalytic Properties for Hydrogenation of Olefins

Polymer-stabilized noble metal colloids were efficiently immobilized on silica by the addition of organic acids under mild conditions. The function of organic acids in the immobilization was studied by infrared spectroscopy. Transmission electron micrographs indicate that the immobilized colloids have a controlled particle size and size distribution. They serve as catalysts in the hydrogenation of cyclohexene and cyclopentadiene, the results of which show that this new type of immobilized colloid has high selectivity and good stability.     

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.     

Metal Nanoparticle/Polymer Hybrid Particles: The Catalytic Activity of Metal Nanoparticles Formed on the Surface of Polymer Particles by UV-Irradiation

Summary: Polymer particles decorated with metal nanoparticles were prepared by UV-irradiation of polystyrene particles incorporating polymethylphenylsilane (PS/PMPS) and P[S-co-NIPAM]/PMPS particles (NIPAM: N-isopropyl acrylamide) in the presence of metal salts. The metal nanoparticle/polymer hybrid particles were used as a catalyst for the reduction of 4-nitrophenol with NaBH₄. The Pd- and Ag-P(S-co-NIPAM)/PMPS hybrid particles had larger metal nanoparticles and the lower catalytic activity than those of Pd- and Ag-PS/PMPS, respectively. The surface functional group of the polymer particles affected the formation of the metal nanoparticles and their catalytic activity.     

Metal Nanoparticle/Polymer Hybrid Particles: The Catalytic Activity of Metal Nanoparticles Formed on the Surface of Polymer Particles by UV-Irradiation

Summary: Polymer particles decorated with metal nanoparticles were prepared by UV-irradiation of polystyrene latex particles incorporating polymethylphenylsilane (PS/PMPS) and P[S-co-NIPAM]/PMPS particles (NIPAM: N-isopropyl acrylamide) in the presence of metal salts. The metal nanoparticle/polymer hybrid particles were used as a catalyst for the reduction of 4-nitrophenol with NaBH₄. The Pd- and Ag-P(S-co-NIPAM)/PMPS hybrid particles had larger metal nanoparticles and the lower catalytic activity than those of Pd- and Ag-PS/PMPS, respectively. The surface functional group of the polymer particles affected the formation of the metal nanoparticles and their catalytic activity.     

Acidity and Catalytic Activity of Sulfate Modified Mixed Oxides of Tin and Praseodymium

A comparitive study of the acid-base properties and physico-chemical characteristics of pure SnO₂, sulfated SnO₂ and sulfated binary oxides of Sn and Pr was done. The data were correlated with the catalytic activity of the oxides towards benzoylation of toluene.     

Catalytic and Optical Behavior of Polymer Embedded Metal Nanoparticles

Very small metal aggregates (nanoaggregates) embedded in an inert polymer matrix, which simply stabilizes the nanodispersion, show unique catalytic and optical behaviour. Indeed Ru-nanoparticles in vinyl-aromatic polymers or polyphosphazenes display an enhanced reactivity for hydrogenation of different groups, such as aromatic rings, keto and nitro groups, oximes and nitriles which are converted into the corresponding saturated derivatives under mild conditions. The optical properties of terthiophenethiol-coated gold nanoparticles in UHMWPE (concentration lower than 4 wt.%) are characterized by poor dichroism due to their centrosymmetric structure. High dichroism (R = 30 at 400 nm, DR = 30) is on the contrary recorded for the terthiophene band showing the chromophores to be sensitive to mechanical orientation also when complexed with gold. On the other hand, nanocomposites based on polymers containing vinyl alcohol units and dispersed gold nanoparticles with average diameter ranging from 3 to 20 nm have been efficiently prepared by an UV photo-reduction process. Uniaxial drawing of the irradiated Au/polymer nanocomposites favours the anisotropic distribution of packed assemblies of gold particles, providing oriented films with polarization-dependent tunable optical properties.     

铜铈协同作用对CuCeMgAl(O)催化活性的影响

ＦＣＣ(流化催化裂化)是炼厂生产汽油的主要方法之一.ＦＣＣ中ＮＯｘ的排放量约占空气中其总量的10%[1].ＦＣＣ再生器烟气中ＮＯｘ的浓度为0.005%0.05%(,体积分数,下同),主要是ＮＯ(约为90%),同时含有少量的ＮＯ2.此外,在烟气中还存在着Ｏ2、ＣＯ、Ｈ2Ｏ等气体.由于ＮＯｘ能形成酸雨和光化学烟雾,破坏臭氧层,损害人体健康.因此,近20年来人们对ＤｅＮＯｘ催化剂进行了广泛的研究.鉴于ＦＣＣ的烟气中存在着ＣＯ,用ＣＯ做还原剂是同时消除ＮＯ和ＣＯ的最佳途径.对于ＮＯ和ＣＯ反应,含铜催化剂有高的催化活性[2-5],遗憾的是所有这些催化剂都…