Synthesis and characterization of molybdenum incorporated mesoporous aluminophosphate

A synthesis of molybdenum incorporated mesoporous aluminophosphate with long-chain n-alkylamine as template material had been prepared under non-aqueous condition. These materials were extensively characterized by using X-ray diffraction (XRD), nitrogen sorption isotherms, nuclear magnetic resonance of ²⁷Al and ³¹P (NMR), inductive coupled plasma (ICP), electron spin resonance (ESR), Fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG-DTA). Morphology of the materials had been observed by using transmission electron microscope (TEM) that revealed the mesoporous materials possessed wormhole-like structures. Alkaline solvent extraction using n-butylamine/ethanol had been efficiently removed the n-alkylamine from the mesoporous samples which yielded BET surface areas around 550-730 m²/g. BJH analysis showed a narrow pore size distribution which increased with increasing of the carbon chain length of alkylamine (template). Valence state and coordination of the molybdenum in the obtained samples were investigated by using ESR and FTIR where it was found that Mo⁴⁺ and Mo⁶⁺ molybdenum species existed in the molybdenum incorporated mesoporous aluminophosphate in tetrahedral coordination.     

Heat-treatment studies of molybdenum oxide-monohydrate

The dehydration of molybdic acid, MoO₃---H₂O, was studied by thermal analysis, X-ray diffractometry and FTIR spectroscopy. The results show that an intermediate phase, MoO₃-2/3H₂O is formed at 216 °C and the monoclinic form of MoO₃ is grown above 350 °C. The mechanism of dehydration and structural rearrangement were confirmed by the features of the infrared spectra showing formation of corner-shared MoO₆ octahedra.     

Synthese und Eigenschaften von Sr3Mo1.5Zn0.5O7‐δ, einer Phase mit perowskitverwandter Schichtstruktur

Synthesis and Properties of the Layered Perovskite Phase Sr₃Mo_1.5Zn_0.5O_7‐δ The new layered perovskite phase Sr₃Mo_1.5Zn_0.5O_7‐δ was synthesized by solid state reaction using a Zn/ZnO oxygen buffer. The crystal structure was refined from X‐ray powder pattern by the Rietveld method. The compound crystallizes tetragonal in the space group I4/mmm (no. 139) with the lattice parameters a = 3.9631(3) Å, c = 20.583(1) Å. An oxygen deficiency corresponding to δ ≈ 0.25 was determinated, indicating the presence of molybdenum in mixed valence (Mo⁴⁺ and Mo⁶⁺).     

Vapour and plasma ignition thresholds for visible pulsed-laser ablation of metallic targets

The coupling of visible nanosecond laser pulses to metallic targets irradiated in vacuum is studied. The expressions of the vapour and plasma ignition times are obtained. Two cases for vapour breakdown in the plasma ignition process are considered. The first case is that 40 generations of new electrons are born in vapour generation time before plasma formation as assumed in the literature. The second case is that 10 generations of new electrons are born in vapour generation time. Molybdenum (Mo), niobium (Nb) and aluminium (Al) targets are considered for illustrations of our results. The expression of the plasma ignition time for the Al target is substantially different from that reported in the literature. The vapour and plasma ignition threshold laser intensities are calculated and compared with those reported in the literature. Reasons for disagreement are discussed. The plasma ignition threshold estimated in the second case is noted to be in good agreement with the reported experimental result.     

A photoemission study of molybdenum hexacarbonyl adsorption and decomposition on TiO2(1 1 0) surface

The adsorption and decomposition of molybdenum hexacarbonyl on (1 1 0) TiO₂ surfaces were studied using both core levels and valence band photoemission spectroscopies. It was found that after an adsorption at 140 K, when going back to room temperature, only a small part of molybdenum compounds, previously present at low temperature, remained on the TiO₂ surface. This indicates that the desorption temperature on such a surface is lower than the decomposition one. The use of photon irradiation to decompose the hexacarbonyl molecule was also studied. It was shown that during such a decomposition molecular fragments were chemisorbed on the surface allowing a higher amount of metal to remain on the surface. It was also shown that it was possible to get rid of adsorbed subcarbonyl groups and to organize the metal atoms by thermal treatments at temperatures as low as 400 K, i.e. much lower than the one needed to obtain the same structures using physical vapour deposition (PVD). Moreover, due to lower used temperatures, this chemical way of deposition allows a better control of the interface than during PVD growth.     

Electrolytical production of Ni + Mo + Si composite coatings with enhanced content of Si

Ni + Mo + Si composite coatings were prepared by co-deposition of nickel with molybdenum and silicon powders from a nickel solution in which Mo and Si particles were suspended by stirring. The layers have been deposited on a carbon steel substrate (St3S) under galvanostatic conditions. The content of Si in deposited layers was about 2-5 wt.% depending on deposition current density and the value of electric charge. For comparison Ni + Mo composite coatings were obtained under analogous current conditions. Composite coatings of enhanced Si content (15 wt.%) were deposited from an electrolyte in which 40 g/dm³ of Si covered with electroless plated nickel was dispersed. Deposition current density was equal 0.1 A/cm² and the value of electric charge Q = 500 C/cm². The thickness of the coatings was about 100-300 μm depending on their kind, electric charge and the deposition current density. Surface and cross-section morphology were investigated by scanning electron microscope (SEM). All deposited coatings are characterized by great, developed surface area. No internal stresses causing their cracking were observed. Chemical composition of the layers was determined by X-ray fluorescence spectroscopy (XRF) method and quantitative X-ray analysis (QXRD). It was stated, that the content of molybdenum and silicon in Ni + Mo + Si coatings depends on deposition current density and the amount of the powder in bath. The results of structural investigation of the obtained layers by the X-ray diffraction (XRD) method show, that they consist in crystalline Mo or Mo and Si phases built into Ni matrix. Moreover, Ni + Mo + Si composite coatings were modified by thermal treatment. It has been found that the thermal treatment of Ni + Mo + Si composite coatings caused that the new phases (NiSi, Mo₂Ni₃Si and Ni₆Mo₆C_1.06) were obtained.     

Synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine and (±)-convolutamydines A and E, through enolization-Claisen rearrangement of 2-allyloxyindolin-3-ones

Claisen rearrangement triggered by enolization of 2-allyloxyindolin-3-ones with DBU was performed in order to prepare 3-allyl-3-hydroxyindolin-2-ones. Total synthesis of 3-hydroxyindolin-2-one alkaloids, (±)-donaxaridine, as well as (±)-convolutamydines A and E, was achieved by transformation of the allyl moiety of 3-allyl-3-hydroxyindolin-2-ones.     

若干具有[(PO4)2Mo5O15]簇骼的化合物的光谱研究

本文对所合成的具有 [(PO4 ) 2 Mo5O1 5]簇骼的 3种新颖的有机 磷钼酸盐簇合物(NH3CH2 CH2 NH3) 2 5[(PO4 ) (HPO4 )Mo5O1 5]·7 5H2 O (Ⅰ ) ,(H3NCH2 CH2 NH3) 3·[(PO4 ) 2 Mo5O1 5]·3H2 O (Ⅱ )和(H3NCH2 CH2 NH3) 2 ·[Cu(en) ][(PO4 ) 2 Mo5O1 5]·5H2 O (Ⅲ )用FTIR ,NIR Raman ,紫外 可见漫反射光谱 (UV VisDRS)和荧光光谱等研究手段 ,对其进行光谱研究 ,探讨其结构和性能的关系。在这些化合物中 ,化合物Ⅰ和Ⅱ具有孤立的 [(PO4 ) 2 Mo5O1 5]簇骼基元 ,而化合物Ⅲ的 [(PO4 ) 2 Mo5O1 5]簇骼基元是由 [Cuen]基团桥联成链 ;磷钼酸盐的特征振动频率和这些化合物的结构相关 ;UV VisDRS显示 ,在 2 0 0和 2 6 0nm左右有两个杂多化合物的特征吸收谱带 ;化合物的稳态荧光光谱中 ,观察到以 2 4 0nm激发 ,在大约 4 0 0nm附近出现的由金属氧簇Oμ→Mo跃迁激发所引起的较强的发射峰 ,在化合物 (Ⅲ )中 ,还观察到通过 [Cuen]的荷移跃迁的以 5 70nm激发所产生的 6 0 4nm的发射峰。     

Preparation and Characterization of a Cobalt‐Containing Mono‐Phosphine Ligand and its Coordinated Molybdenum Complex

A cobalt‐containing monodentate phosphine [(μ₂‐PPh₂CH₂PPh₂‐κ²P)Co₂(CO)₄][μ₂‐η²‐PhC≡CP(i‐Pr)₂] 2f , was prepared from the reaction of (μ₂‐PPh₂CH₂PPh₂‐κ²P)Co₂(CO)₆ 1 with PhC≡CP(i‐Pr)₂. It was accompanied by an oxidized compound, [(μ₂‐PPh₂CH₂PPh₂‐κ²P)Co₂(CO)₄][μ₂‐η²‐PhC≡CP(=O)(i‐Pr₂)] 2fo during the chromatographic process. Further reaction of 2f with Mo(CO)₆ resulted in the formation of a 2f ‐ligated molybdenum complex 4 , [(μ₂‐PPh₂CH₂PPh₂‐κ²P)Co₂(CO)₄][μ₂‐η²‐PhC≡CP(i‐Pr₂)‐κP]‐Mo(CO)₅.     

一种新型的磷化钼加氢精制催化剂的研究

通过(NH4)Mo7O24·4H2O和(NH4)2HPO4水溶液沉淀、焙烧在923K用H2还原制得磷化钼催化剂.XRD检测表明,用H2还原后有纯的磷化钼生成.在3.0MPa的高压连续微反系统中测定催化剂的加氢活性.以制备的磷化钼为活性组分、γ-Al2O3为稀释剂,考察了空速、反应温度和反应时间对模型化合物的HDN、HDS和HDY性能的影响,结果表明:在合适的条件下,其脱硫脱氮率可达到90%以上.模型化合物为吡啶、噻吩和环己烯,吡啶含量以N计(为0.2%)、噻吩含量以S计(为0.3%),环己烯含量为20%,以环己烷作溶剂.