Mechanism of methanol decomposition on the Pd/WC(0001) surface unveiled by first-principles calculations

In this study, the decomposition of methanol into the CO and H species on the Pd/tungsten carbide (WC)(0001) surface is systematically investigated using periodic density functional theory (DFT) calculations. The possible reaction pathways and intermediates are determined. The results reveal that saturated molecules, i.e., methanol and formaldehyde, adsorb weakly on the Pd/ WC(0001) surface. Both CO and H prefer three-fold sites, with adsorption energies of −1.51 and −2.67 eV, respectively. On the other hand, CH₃O stably binds at three-fold and bridge sites, with an adsorption energy of −2.58 eV. However, most of the other intermediates tend to adsorb to the surface with the carbon and oxygen atoms in their sp³ and hydroxyl-like configurations, respectively. Hence, the C atom of CH₂OH preferentially attaches to the top sites, CHOH and CH₂O adsorb at the bridge sites, while COH and CHO occupy the three-fold sites. The DFT calculations indicate that the rupture of the initial C–H bond promotes the decomposition of CH₃OH and CH₂OH, whereas in the case of CHOH, O–H bond scission is favored over the C–H bond rupture. Thus, the most probable methanol decomposition pathway on the Pd/WC(0001) surface is CH₃OH → CH₂OH → trans-CHOH → CHO → CO. The present study demonstrates that the synergistic effect of WC (as carrier) and Pd (as catalyst) alters the CH₃OH decomposition pathway and reduces the noble metal utilization.     

成熟油田应用技术的潜能开发

成熟油田应用技术的影响力和潜力是巨大的,技术的有效开发和推广应用对油田的可持续发现和发展至关重要.业界达成共识,生产经营者与供应商之间的有效沟通以及技术方案的有效应用是开发技术潜力的关键.     

利用中石油域用户认证系统实现数据存储备份

系统面向中石油域用户提供了安全、高速的数据传输服务.实现了数据传输DES加密、用户登录LDAP限制、系统安全审计、空间容量扩容等功能.充分利用SAN网络光存储设备,同时也为油田网络存储应用的开发提供了成功经验.     

吴岭水库土坝渗流及坝坡稳定性分析

本文对湖北省京山县吴岭水库土坝进行了有限元渗流计算和坝坡稳定性计算,在分析大坝基础部位的残坡积土、强风化砂岩的强透水性和下游排水体对于大坝渗流场的影响的基础上,得出渗流是引起下游坝坡不稳定的主要因素,为大坝的加固处理提供了理论依据,也可供同类土坝设计时参考。     

国际咨询工程师联合会(FIDIC)2005年年会中国·北京2005年9月4日--8日欢迎辞

世界工程咨询业的精英们将齐聚中国北京,参加国际咨询工程师联合会(FIDIC)2005年年会、成员协会代表大会和中国商机展示、推介、洽谈会.     

The new structure of fibre glass reinforced plastics bolt

The develop actuality and direction of FRP (fibre glass reinforced plastics) bolt in the world are analyzed. The new type structure of FRP bolt was designed. Trial data indicate that, all kinds of capability target of this FRP bolt all achieve and exceed the country stand-ard, substitute present metal bolt, wood bolt and bamboo bolt and other side bolt, it can gain magnitude technology and economy benefit. FRP bolt mechanization product line produce ef-ficiency is high, its throughput a day are 750 base, this can meet demand of hit-small mining company.     

Enhanced electron emission from phosphorus-doped diamond-cladsilicon field emitter arrays

Undoped and phosphorus (P)-doped diamond-clad Si field emitter arrays have been successfully fabricated using microwave plasma chemical vapor deposition (MPCVD) technology. The electron emission from the blunt diamond-clad microtips are much higher than those for the pure Si tips with sharp curvature due to a lower work function. Furthermore, the characteristics of emission current against applied voltage for the P-doped diamond-clad tips show superior emission at lower field to the undoped ones. After the examination of Auger electron spectroscopy (AES) and electrical characteristics of as-grown diamond, such a significant enhancement of the electron emission from the P-doped diamond-clad tips is attributed to a higher electron conductivity and defect densities     

硼／铝复合材料管构件的界面特性EI

主要研究带钛合金连接头硼／铝复合材料管构件中Ｂ－Ａｌ－Ｔｉ间的界面结构与性质。研究表明，在复合工艺条件下，硼－铝界面附近没有检测到任何铝－硼化合物，而钛－铝间形成ＴｉＡｌ有序金属间化合物相。实验证明，硼／铝复合材料与铝合金端环之间采用的固结方法是有效的，且可按照受载类型随意调整斜面搭接长度，达到承受不同载荷的目的。