Na2S滴定法测定Pd／C催化剂制备过程中H2PdCl4前驱体的吸附

为了研究Pd前驱体在活性炭表面的平衡吸附量和吸附态,了解影响Pd/C催化剂中Pd粒径的因素以及Pd颗粒的生长过程,提出了使用Na2S滴定法测定Pd/C催化剂制备过程中H2PdCl4在活性炭载体上平衡吸附量的方法,比较研究了一次性和逐滴性前驱体加入方式对Pd/C催化剂中Pd粒径的影响,实验结果表明逐滴加入法制备所得的催化剂的Pd粒径明显小于一次性加入法制备的催化剂,但H2PdCl4在活性炭表面平衡吸附量的变化并不如此明显,表明Pd前驱体平衡吸附量与催化剂Pd粒径之间并不存在对应关系.由H2-TPR实验结果可知,与一次性加入法制备Pd/C催化剂相比,逐滴加入法制备Pd/C催化剂的过程中发生还原的Pd前驱体较多.由此推断在催化剂制备过程中,Pd金属粒径的生长主要受到Pd0初始晶核的生成速率及前驱体扩散速率的影响.     

二氧化钛厚膜钯表面扩散状态对氧气响应特性影响

利用二氯化钯(PdCl2)溶液浸渍法,研究了二氧化钛(TiO2)厚膜钯(Pd)原子表层扩散对氧气响应特性的影响.扫描电子显微镜显示:Pd扩散后厚膜表面均匀分布着纳米级Pd晶粒.利用Kroger-Vink方程分析了不同扩散时间下对应的lnR-lnpo2曲线,针对不同斜率的曲线,用缺陷方程分析了Pd元素的分布状态.样品响应特性的伏安法测试结果显示:820℃,2h扩散的敏感膜具有理想灵敏度和响应时间.研究结果表明:Pd元素在敏感膜表面形成了纳米级Pd晶粒,并在TiO2厚膜表层中存在着少量的钯间隙原子(Pdi)及替位钯离子(Pd2 ).合理的扩散温度和扩散时间,可获得表层Pd氧化量最少、扩散浓度合适的敏感膜,进而获得效果理想的厚膜氧敏材料.     

Pd/PMAA/PVDF复合膜制备及催化性能研究

制备了一种Pd/PMAA/PVDF复合催化膜用于催化氧化苯甲醇制备苯甲醛.首先通过蒸馏-沉淀聚合法制备了PMAA微球,然后将PMAA微球与PVDF共混,利用浸没沉淀相转化法制备了PMAA/PVDF基膜,随后在PMAA微表面原位还原生成Pd纳米粒子,制备了Pd/PMAA/PVDF复合膜.通过FTIR、XPS、SEM等对膜...     

添加ZrO2的Pd/Al2O3催化剂及其催化蒽醌加氢性能

以四氯合钯（II）酸（H2PdCl4）为前体,活性氧化铝（Al2O3）为载体,硝酸锆（Zr（NO3）4）为添加组分,采用不同方式的分步浸渍法制备了添加ZrO2的Pd/Al2O3催化剂。考察了制备方法和反应条件对催化剂蒽醌加氢催化性能的影响,发现催化剂活性与制备方法有关。当对添加锆的载体进行适当焙烧,控制Pd负载量为0.3%,还原温度低于300℃时,催化剂的蒽醌加氢活性较高,与未添加ZrO2的催化剂相比提高了约20%。X射线衍射（XRD）、氮气物理吸附（BET）、透射电镜（TEM）、X光电子能谱（XPS）和程序升温还原（TPR）等表征对催化剂物相结构、比表面积、表面形貌及组分间相互作用的分析表明,ZrO2的掺杂提高了载体Al2O3的高温稳定性,改善了催化剂中活性组分Pd与载体间的相互作用,促进了Pd在载体表面的分散,从而提高了催化活性。     

Pd/TiAl膜的制备研究

采用无电镀技术在多孔TiAl金属问化合物支撑体上制备了Pd膜.用SEM测定Pd膜的表面和断面的形貌,EDS测定从膜层到支撑层元素的组成,结果表明,支撑体表面形成了均匀致密的Pd膜,膜层的主要成分是单质Pd,所制钯膜的厚度为2～3μm.在350℃～500℃的温度范围内考察Pd膜透氢性能,当500℃,0.1 MPa时,H2的渗透系数为4.0×10-6mol·m-2·s-1·Pa-1,H2/N2的分离系数为30.测得本文所制备Pd膜的活化能为10.8 kJ/mol.     

微乳法制备Pd-Cu双金属催化剂

选择Cu为助剂,采用微乳法分别优选具有较好稳定性的Cu和Pd微乳液体系,并将Cu和Pd依次负载于Al_2O_3载体上,经干燥、活化和还原制备了Pd-Cu/Al_2O_3催化剂。采用原位IR、CO化学吸附和HRTEM等对催化剂进行表征,结果表明,与常规溶液负载法制备的Pd-Ag/Al_2O_3催化剂相比,采用微乳法降低了催化剂表面酸性,提高了活性组分Pd分散度,Pd粒径分布更为均匀。在750 mL加氢反应器中,采用C_2后加氢原料对催化剂性能进行评价,结果表明,与常规溶液负载法相比,微乳法制备的催化剂在反应温度低4℃条件下,乙炔转化率相当,选择性高9.9个百分点,绿油生成量较低。微乳法制备Pd-Cu双金属催化剂具有良好的工业应用前景。     

采用新型无锡活化工艺在γ-Al2O3粉体上化学镀钯的研究

采用一种新型无锡活化工艺,即利用乙二醇作还原剂直接使Pd2+被还原成Pd0而沉积在基体上,实现了对γ-Al2O3粉体的活化.将活化后的γ-Al2O3粉体加入到两种钯镀液中,成功实现了γ-Al2O3粉体上的化学镀钯.研究了活化的机理以及化学镀前后γ-Al2O3粉体结构与表面形貌的变化,结果表明通过新型化学镀方法制备出的镀钯粉体1-Pd/Al2O3中钯粒子的粒径在20-30nm,并且粒径大小分布均匀.新型无锡活化工艺与传统的化学镀活化工艺相比,活化过程中无锡离子干扰,并且活化在中性条件下进行,基体不受损坏.     

α-Al2O3多孔陶瓷上化学镀Pd膜工艺研究

用浸渍–高温还原法活化和化学镀法在α-Al2O3多孔陶瓷上制备了Pd膜。主要考察了浸渍法的改善、肼加入方式、化学镀温度、氯化钯浓度对钯复合膜微观结构的影响。研究结果表明:超声波的应用可以改善活化;肼的分批加入可以改善钯膜的质量;温度60°C、氯化钯质量浓度2.0g/L较适宜;钯膜的微观结构为竖直或斜方向类柱状沉积层。     

Pd／C和Pd／Al2O3模型催化剂经热处理后的结构变化

用氩离子溅射法所制备的Pd/C和Pd/Al_2O_3两种模型催化剂,在氢气中进行热处理,用电镜测定结果表明,随着加热温度的升高两者晶粒大小和物相的变化有很大差别。前者晶粒长大速度快,在高温下Pd仍以原子形式担载在活性炭表面上,未形成新的物相,而后者晶粒长大速度慢,Pd与Al_2O_3发生电子交换形成新的物相,这意味着Pd在炭和Al_2O_3表面上的相互作用不同而导致抗烧结性能的差异。     

光催化沉积法制备Pd膜的改进及Pd膜性能表征

对光催化沉积法(PCD)制备Pd膜进行了改进,使含有TiO2与Pd2 的悬浮液膜层在多孔陶瓷膜表面形成液体薄膜,该薄膜在紫外光直接照射下发生光催化还原反应,烧结后得到含TiO2及Pd晶种的超薄膜层,用化学镀修饰得致密Pd膜.采用SEM、EDAX方法对所制的Pd膜表征结果表明,Pd膜厚度为5~6μm.在350~500℃和0.05~0.15 MPa下进行气体渗透实验,当温度为450℃时,H2渗透系数为4.07×10-6mol/(m2.s.Pa),N2的渗透量检测不出,高温热循环测试表明该Pd膜致密且具有良好的热稳性.     

Interaction of Some Non-Platinum Metal Anticancer Complexes With Nucleotides and DNA and The Two-Pole Complementary Principle (TPCP) Arising Therefrom

The binding modes of some non-platinum metal anticancer complexes, Cp(2)TiCl(2), Cp(2)ZrCl(2), (CH(3))(2)SnCl(2), (C(2)H(5))(2)SnCl(2), (C(2)H(5))(2)SnCl(2)(phen) (phen=Phenanthroline) and cis-Ru(II)Cl(2)(DMSO)(3) (DMSO) (cis-RDT) with nucleotides and DNA in aqueous solution at physiological pH values were investigated by various modern techniques. 5'-dGMP with Cp(2)TiCl(2) or cis-RDT forms chelate complexes in which both N(7) and phosphate of dGMP bind to the metal center. Whereas Cp(2)ZrCl(2) and all the diorganotin compounds can bind dGMP only via the phosphate group. The investigations of the interactions between Cp(2)TiCl(2) or (C(2)H(5))(2)SnCl(2) and DNA indicate that there are two types of binding sites on DNA for Cp(2)TiCl(2), i.e., the base nitrogen rings and the phosphate group, while (C(2)H(5))(2)SnCl(2) can bind to DNA only via the phosphate group. At last, by carefully comparing and analysing the binding modes-activity relationships of the above anticancer complexes and other non-platinum and platinum anticancer complexes, a hypothesis named "Two-Pole Complementary Principle" was put forward.     

Electroless plating of polymers: XPS study of the initiation mechanisms

This paper deals with polymer metallization by the electroless process. Previous studies in the authors' laboratory have shown the interest of plasma surface treatments of polymers before chemical metallization and the significant role they play towards the chemisorption of a catalyst (Pd2+ ions). Three different processes are used to activate the polymer surface for electroless deposition: namely, the one-step process using a mixed SnCl2–PdCl2 solution, the conventional two-step process using SnCl2, then PdCl2, and a new simplified process (using only PdCl2), previously proposed by the authors. According to the process utilized a variable initiation time is observed before metal deposition takes place in the metallization bath. The surface phenomena occurring on the polymer during this initiation time are studied by XPS through the chemical form of palladium adsorbed on the surface and through changes in the Pd surface concentration. A reaction mechanism relative to the initiation of the metallic ion reduction is proposed.     

氧化还原法测定铁矿石中铁含量的方法探讨

重铬酸钾法测定铁矿石中铁含量有三种还原铁的方法。实验表明用SnCl2-HgCl2法结果最为准确,TiCl3-Na2WO4法次之,而用甲基橙法结果误差最大。     

液相沉积法制备金云母钛珠光颜料

以耐高温性能优于绢云母的金云母为基材,TiCl4为沉淀剂,SnCl4为晶型促进剂,通过液相沉积法成功制备金云母钛珠光颜料。通过X射线衍射(XRD)和扫描电子显微镜(SEM)分析对金云母钛珠光颜料的结构进行表征,重点探讨了该种液相沉积法对金云母钛珠光颜料的制备效果。结果表明TiO2纳米粒子均匀地包覆于金云母表面,且TiO2纳米粒子粒径均匀,分散性好。     

TiCl_4-AlCl_3-O_2高温反应合成TiO_2-Al_2O_3纳米复合颗粒

引　言纳米粉体制备是获得纳米陶瓷的重要前提[1] .ＴｉＯ2 和Ａｌ2 Ｏ3 复合陶瓷热膨胀系数小、熔点高、抗震性好 ,是很有发展前途的高温结构材料[2 ] .通常采用球磨法[3] 实现ＴｉＯ2 和Ａｌ2 Ｏ3 粉共混 ,但往往得不到微观均匀混合的纳米粉体 .Ｗｏｉｇｎｉｅｒ等[4 ] 采用醇盐共水解Ｓｏｌ -Ｇｅｌ法 ,成本高、反应时间长 ;Ｏｋｕｍｕｒａ等[5] 利用烷氧基钛水解反应在Ａｌ2 Ｏ3颗粒表面包覆ＴｉＯ2 ,该法均匀性差 ,且需严格控制原料滴加速度、反应时间较长 .气相反应法快速高效 ,能直接获得金属氧化物晶体 ,产物纯度较高 ,已用于制备Ｔ…     

Biodiesel synthesis via metal oxides and metal chlorides catalysis from marine alga Melanothamnus afaqhusainii

This research article demonstrates the most comprehensive comparative catalytic study of different metal oxides and metal chlorides towards the methanolysis of triglycerides of marine red macroalga Melanothamnus afaqhusainii.CaO was found to be the most reactive metal oxide that yielded 80% biodiesel while ZnCl_2 was the most reactive metal chloride that produced 60% biodiesel by mechanical stirring for 6 h at 100–110 °C.The overall reactivity order of the catalysts was found to be CaOMgOPbO_2ZnCl_2TiCl_4PbOHgCl_2ZnOAlCl_3SnCl_2TiO_2whereas,CaCl_2,MgCl_2,Al_2O_3,HgO,PbCl_2,MnO_2,MnCl_2,Fe_2O_3 and FeCl_3 were found to be non-reactive for transesterification of triglycerides.In addition,a detailed study of the screening of mobile phases and spraying reagents was conducted which showed that petroleum ether :chloroform :toluene(7:2:1)is the best mobile phase,whereas iodine crystals/silica gel is the best visualizing agent for the thin layer chromatography(TLC)examination of biodiesel.Biodiesel production was confirmed by comparative TLC examination.It was further supported by the determination of fuel properties of biodiesel,which were found to be similar to the standard limits of American Society for Testing and Materials(ASTM).     

Molecular simulation on the interaction of TiCl4 with the surface of β-MgCl2（110）

利用基于密度泛函理论的量子力学从头计算方法对TiCl4和其失去部分Cl原子后的离子[TiCl3]+、 [TiCl2]2+、[TiCl]3+在β-MgCl2（110）面上的吸附作用进行了研究。通过模拟计算其吸附能、键长和电子云分布,发现TiCl4和β-MgCl2（110）面上作用力很弱,而只有TiCl4失去部分Cl原子后带上正电荷,才能与β-MgCl2（110）面形成强的化学键。     

核壳聚合物负载茂金属催化剂及乙烯聚合

采用半连续种子乳液聚合法,得到了粒径为280 nm左右的以聚甲基丙烯酸甲酯 (PMMA)为核、聚苯乙烯(PS)为壳的PMMA/ PS核壳结构聚合物和以PS为核、PMMA为壳的PS/PMMA核壳结构聚合物.并分别以上述二种核壳聚合物为载体,超临界CO2为溶剂,采用超临界流体浸渍法负载二氯二茂钛(Cp2TiCl2)催化剂,得到PMMA/PS-Cp2TiCl2和PS/PMMA-Cp2TiCl2两种负载型的茂金属催化剂颗粒.通过对二种催化剂颗粒的乙烯淤浆聚合动力学的研究发现,PMMA/PS-Cp2TiCl2催化剂颗粒的聚合反应速度有很大的滞后效应,聚合最大反应速率出现在第9 min,而PS/PMMA-Cp2TiCl2催化剂颗粒动力学行为与Cp2TiCl2催化剂均相聚合相似.     

The effect of lanthanum in dehydrogenation of propane on Pt-Sn bimetallic catalysts

Four catalysts, H2PtCl6-5SnCl2/γ-Al2O3 (cat-1), { H2PtCl6-5SnCl2 + xLaCl3 } / γ-Al2O3 (cat-2), (Me4N)[Pt(SnCl3)5]/ γ-Al2O3 (cat-3), and {(Me4N)[Pt(SnCl3)5] + xLaCl3} / γ-Al2O3 (cat-4) were prepared and their catalytic activities and stabilities in dehydrogenation of propane were investigated. It has been shown that the stabilities of the Pt-Sn bimetallic catalysts were improved by introducing lanthanum into the catalysts either by the conventional impregnation method with Pt- and Sn-containing salts or by using precursors derived from Pt-Sn bimetallic clusters. Results from XPS analysis indicated that addition of lanthanum could inhibit the reduction of tin in the catalysts, especially in cat-2. The distribution of pore capacity in a used cat-2 was mainly in the large and medium size range, but in a used cat-1 the distribution was mainly in the small to medium size range. Thermal gravimetric analysis (TGA) showed that weight loss in the used cat-1 was much more than that in the used cat-2. The results suggested that introducing lanthanum into the Pt-Sn bimetallic catalysts could effectively prevent them from coking. This revised version was published online in July 2006 with corrections to the Cover Date.     

(C2H5)2AlCl/TiCl4催化1-癸烯聚合制备高黏度指数润滑油

以(C₂H₅)₂AlCl/TiCl₄为催化剂研究了1-癸烯聚合制聚烯烃基础油。比较烯烃原料和溶剂对聚α-烯烃性能的影响,探讨催化剂用量、Al与Ti物质的量比、反应时间和反应温度等工艺条件对合成油性能的影响。结果表明,(C₂H₅)₂AlCl/TiCl₄催化剂对1-癸烯聚合具有较高的活性;溶剂极性越大,聚α-烯烃的枝化度越大,从而导致黏度指数降低。100 ℃的运动黏度随着Al与Ti物质的量比不同而变化,因此,可以通过调节Al与Ti物质的量比,制备各种黏度的聚α-烯烃。以(C₂H₅)₂AlCl/TiCl₄ 为催化剂,1-癸烯聚合的最佳反应条件：反应温度80 ℃,反应时间4 h,催化剂用量为反应物总质量的4.0%,此条件下聚α-烯烃收率为75.6%,黏度指数高达173。