Comparing Al-SBA-15 Support and Pt/Al-SBA-15 Catalyst: Changes in Al Speciation and Acidic Properties Induced by the Introduction of Pt via Aqueous Medium

Differences between the acidic properties of silicoaluminic Pt-containing catalysts and those assessed on their parent supports have been reported in the literature and attributed to the presence of the metal nanoparticles and to their influence on the acid sites. It is shown here that for mesoporous materials containing various types of Al species, an alternative explanation can be proposed. ²⁷Al NMR spectroscopy, FTIR of adsorbed CO and probe catalytic tests suggest the redistribution of aluminium atoms upon contact of the parent support with the aqueous solution containing the Pt precursor. Upon contact with water and thermal treatment, strong and mild Brønsted sites (Si–O(H)–Al) transform into strong Lewis sites (isolated tetracoordinated Al atoms). As a consequence, it may not be straightforward to deduce the acidic properties of metal-containing catalysts supported on Al-containing mesoporous materials from those of the bare support, because the surface species may differ significantly.     

城市绿道:河岸绿草地、土堆和房间

项目地点:美国阿肯色州沃伦项目类型:城市规划开工日期:2006年6月该项目获2005年豪瑞可持续建筑大奖赛北美地区提名奖     

断陷盆地群的含油气系统特征——以海拉尔盆地乌尔逊、贝尔凹陷为例

从构造、地层及生、储、盖组合特征出发，以含油气系统的基本原理为依据，划分和比较了乌尔逊、贝尔凹陷6个含油气系统的基本特征，根据各含油气系统的断陷构造样式、断裂发育特征、油气藏类型和分布，总结出双断反转型、断超反转型、断超串型型、简单双断型和无机CO2型共5种类型的含油气系统模式，以此为依据预测了海拉尔盆地其它次级断陷的含油气系统类型。     

油气层序地层学研究的若干问题

油气层序地层学是在地震地层学、层序地层学、石油地质学基础上发展起来的一门综合性新型边缘学科。它实质上是一种含油气层序分析学，在等时地层格架内对油气层序进行成因单元分析。它应用地震层序地层、测井层序地层、露头层序地层分析方法，采用计算机技术和模拟技术研究含油气盆地的地层层序，进行地层对比、盆地生储盖组合和含油气系统分析，进而指出有利的油气勘探方向，特别是非构造油气藏的勘探方向。源于海相含油气盆地的油气层序地层学的基本原理和研究方法，同样也适用于过渡相和陆相含油气盆地。     

Über definierte Polyoxyäthylenderivate. V. [1] Stickstoffhaltige Polyoxyäthylene

On Defined Polyethylene Oxide Adducts. V. Nitrogen Containing Polyethylene Oxide Adducts The authors report on the synthesis and properties of longchain α-hydro-ω-N-alkylamino-polyoxyethylenes, there methylethers, and of α-hydro-ω-N-dodecylacetamidopolyoxyethylenes. Special surface properties as solubility, surface activity and micel formation are discussed.     

End cracking during one-sided submerged-arc welding

Abstract

The mechanical behaviour of end cracking during one-sided SAW was computer-simulated by thermal elastic analysis with the introduction of a dummy element. Experiments on small sized specimens and on-site large specimens have been carried out. The rotational deformation, the mechanism of formation of the end cracking and factors affecting it were investigated. It was concluded that for preventing the formation of end cracks, the end opening displacement and the rate of end opening should be reduced as far as possible. Theoretical analysis and on-site large specimen experiments showed that end cracking can be effectively prevented only if the arrangement of tack welds over the weld end is appropriate, and the stiffness and restraint of slit tab plate are moderate. By the aid of the above mentioned study, end cracking was successfully avoided in over 130 specimens of 12, 14, 16, 18 and 20mm thickness with weld length more than 1000m.     

Detection and analysis of weld penetration in stationary TIG arc welding — a preliminary study

Abstract

A constant voltage microcomputer controlled welding source is used for on-line detection of weld penetration. By adding an instantaneous pulse at regular intervals to the normal welding current the molten pool is excited to oscillate in stationary TIG arc welding. By analysing the signal, the relationship between the frequency of molten pool oscillation and weld penetration is studied and a mathematical model, the weld pool oscillation equation, is established. Using a finite difference equation to solve the eigenvalue problem of the molten pool oscillation, a numerical solution can be obtained. Experimental results obtained from welding 1Cr18Ni9Ti, 20 # and 16Mn steel show good agreement with the theoretical predictions.