Methane Combustion and TPR/TPO Properties of Pd/CexZr1-xO2/Al2O3 Catalysts

Methane Combustion and TPR/TPO Properties of Pd/Ce_xZr_ 1-xO_2/Al_2O_3 Catalysts     

钯氮膦配体络合物催化剂均相催化氯苄双羰基化反应研究

文章研究了用把单膦配体络合物催化氯苄双羰基化反应生成苯基丙酮酸甲酯的催化反应。考察了反应温度、反应压力及催化剂用量对反应产率和选择性的影响。结果表明反应压力达６．０ ＭＰａ后产率无明显变化；反应温度在３７３ Ｋ时，产率和选择性都达到最大值；催化剂用量有一最适宜值，配体不同此值也不同。并探讨了体系的双羰基化反应机理。     

Effect of heat treatment on the anodic oxidation of Ti–0.2 Pd alloys in chloride solutions

The effect of heat treatment of Ti and Ti–0.2 Pd alloys on their anodic oxidation was studied in deaerated 1% NaCl by means of anodic linear sweep voltammetry, SEM, TEM, EDS, optical microscopy and microhardness measurements. The specimens, as fabricated, consisted of -phase only. The -phase, intergranular or with a Widmansttäten type growth, was produced by heat treatment of the Ti–0.2 Pd alloys at the temperature range from 750 to 850 C. The -phase was transformed into the -phase during quenching. The current density against voltage curves for pure Ti and Ti–0.2 Pd, as fabricated or heat-treated, presented an initial plateau at about 1.5 V vs Ag/AgCl/KCl (3 M), an anodic peak at about 4.5 V and a current increase due to the pitting attack at about 10 V. The anodic peak was related to an oxide growth together with a solution electrolysis. Current spikes appeared at random from potentials about 8.3 V, which were related to film breakdown and repair events. The passive films of the alloys oxidized up to about 10 V presented oxidation bands parallel to the surface, with different oxygen content and microhardness, together with a structural transformation of the -phase under the titanium oxide layer. The similar behaviour of pure Ti and Ti–0.2 Pd alloys in front of pitting corrosion in chloride was due to such a structural transformation.     

Pd合金／Si接触过渡层的结构组分研究

淀积合金薄膜的 Si 片退火时,通过固相反应在界面处生成接触过渡层,其组分与结构均不同于一般条件下生成的硅化物.本文介绍了 Pd 合金/Si接触过渡层的形成工艺,对接触过渡层的结构组分进行了分析与讨论.基于“相分层”效应,可用掺氮或掺氧的方法提高阻挡层的质量.     

Pd nanoparticle enhanced re-oxidation of non-stoichiometric TiO2: STM imaging of spillover and a new form of SMSI

We have used STM imaging in situ to demonstrate two fundamental steps in catalytic processes on model catalysts at elevated temperature. We show that Pd nanoparticles on sub-stoichiometric TiO₂(110) dissociatively adsorb O₂ at 673 K which spills over onto the support where further reaction takes place. The spillover oxygen re-oxidises the surface by removing Tiⁿ⁺ interstitial ions trapped in the crystal lattice, preferentially re-growing TiO₂ around and over the particles. The identification of the metal enhanced re-oxidation mechanism may have important and general consequences for the understanding of catalysis and gas sensing.     

Effects of Pd substitution for Ni on corrosion performances of Mg_(0.9)Ti_(0.1)Ni_(1-x)Pd_x hydrogen storage alloys

1 Introduction MgNi-based amorphous hydrogen storage alloys have drawn much attention in the last ten years. Compared with AB5 or AB2 type electrode alloys, the alloy candidates for the negative electrode of Ni-MH batteries possess several advantages, su…     

Core-shell Pd nanoparticles embedded in SnOx films. Synthesis, analytical characterisation and perspective application in chemiresistor-type sensing devices

A two-step bottom up preparation protocol is proposed as a useful tool for the controlled modification of tin oxide films by means of Pd nanoparticles (PdNPs). Colloidal palladium is prepared via an electrolytic process that affords for a core-shell particle structure, while nanostructured tin oxide films are prepared following a sol–gel process. Pd/SnO_x composite layers are obtained adding a proper aliquot of pre-formed PdNPs to the tin oxide precursor solution. The nanomaterials surface chemical composition is addressed by X-ray Photoelectron Spectroscopy. Preliminary results on the application of Pd/SnO_x as active layers in chemiresistor-type gas-sensing devices are reported, as well.     

A novel spectroelectrochemical cell for in situ surface X-ray scattering measurements of single crystal disk electrodes

A newly designed spectroelectrochemical cell was constructed for surface X-ray scattering (SXS) to study single crystal electrodes. Electrochemical characteristics of a specific face of a single crystal electrode can be investigated in the meniscus mode, and SXS measurement can be easily carried out using the spectroelectrochemical cell. The usefulness of the present cell was demonstrated by studying the electrochemical deposition of thin Pd layers on Au(111) and Au(100) that require precise amounts of Pd deposits.     

Pd/C催化剂的制备条件对制备二甲基叔胺的影响

通过浸渍法制备了钯炭催化剂,用于脂肪腈催化加氢制备单烷基二甲基叔胺。通过N2-吸附、透射电子显微镜、X射线衍射等测试手段对催化剂进行物性表征,而且用气相色谱对叔胺产品进行定性分析。在反应温度120℃、反应时间5 h、二甲胺间歇式进料的反应条件下,通过对钯炭催化剂制备条件的优化,表明在pH7.9、浸渍时间15 h的条件下,叔胺含量可以达到95%以上。