70 research outputs found
In situ Time-resolved FTIR and Raman Characterizations of the Partial Oxidation of Methane to Synthesis Gas over Ir/SiO_2 Catalyst
[中文文摘]采用原位时间分辨红外光谱和原位显微Raman光谱技术对Ir/SiO2 上甲烷部分氧化 (POM)制合成气反应的初级产物和反应条件下催化剂表面物种进行了跟踪考察 ,实验结果表明 ,在H2 预还原的新鲜Ir/SiO2 表面 ,CO是V(CH4)∶V(O2 )∶V(Ar) =2∶1∶45混合气反应的初级产物 ,因而甲烷的直接氧化过程是CO生成的主要途径 ;而在稳态反应条件下 ,CO生成的途径可能主要来自CO2 和H2 O与催化剂表面积碳物种 (CHx)和 /或CH4的反应 .催化剂上生成的积碳可能是导致稳态条件下Ir/SiO2 上POM反应机理不同于H2 预还原的新鲜催化剂的主要原因。[英文文摘]In situ time-resolved FTIR and in situ microprobe Raman spectroscopies were used to follow the primary products as well as the surface and gas phase species formed during the reaction of partial oxidation of methane (POM) to synthesis gas over Ir/SiO 2 catalyst. The results suggested that direct oxidation of CH 4 to CO is the dominant pathway of POM reaction over the freshly reduced Ir/SiO 2 catalyst, while the dominant schemes of CO formation over the catalyst under the steady state reaction condition are probably via the reactions of CO2 and H2O with the deposited carbon species (CHx) and/ or CH4 . The mechanistic difference between the POMto synthesis gas over freshly reduced Ir/ SiO2 catalyst and the catalyst under the steady state reaction may have resulted from the formation of significant amount of deposited carbon species in the latter system.国家重点基础研究发展规划 (No.G1999022408); 国家自然科学基金(No.20021002)资助项目
山地城市景观大道打造策略研究
为了更好的提升城市整体发展形象、打造对外交往名片,很多城市新区都计划或已经打造了具有地方特色的景观大道,它不仅是串联了城市的主要功能节点的交通通道,同时还是更加关注街道环境品质、文化风貌的交往街区,是体现人的交流和生活方式、人和城市空间相互关系的纽带。因此,景观大道具有两大功能要素,即“交通”和“交往”。但是,部分城市景观大道在打造过程中,过于追求“大气”,不惜花费大代价,打造出来的景观大道不仅“宽”而且“直”,但是“宽”必加大两侧交往的难度,“直”必难以处理与山地城市自然风貌的和谐关系。基于此,文章试图以对景观大道打造的相关案例分析入手,总结景观大道打造的原则与思路,为山地城市景观大道打造的工作方法提供经验借鉴。</jats:p
多孔硅胶固化吸附剂吸附性能研究
固化吸附剂是提高吸附剂传热性能的重要方式,但是恶化了吸附剂的传质性能。以羧甲基纤维素(CMC)为黏结剂的多孔固化吸附剂利用CMC部分分解,在层间产生丰富的孔道,降低了吸附剂的传质阻力,具有强化吸附剂传质作用。本文对多孔硅胶固化吸附剂开展了容量法吸附性能评价、压汞法测试以及吸附性能计算,结果表明,多孔固化吸附剂层内存在一定量的大孔,改善了吸附剂传质特性;根据细孔扩散和表面扩散的计算方法,分别获得多孔硅胶固化吸附剂的细孔扩散系数和表面扩散系数
Microwave-assisted Preparation of ZnO Nanostructures in Quaternary Ammonium Hydroxide Aqueous Solution
以四丁基氢氧化铵、四乙基氢氧化铵和四甲基氢氧化铵等季铵碱水溶液为反应体系,zn(AC2)和nAOH为原料,微波辅助制备了球状、圆片状、细长薄片状及多脚状等纳米znO;对样品进行了Xrd和SEM表征,分析了微波辅助下纳米znO的可能生长过程.结果表明:季铵阳离子能有效屏蔽晶核;季铵碱浓度越高,OH-浓度越高,或者前驱体zn(OH)42-浓度越低,则样品粒径越小且越趋于球状.ZnO nanoparticles were synthesized by microwave heating,using Zn(Ac)2·2H2O and NaOH as raw materials,in the solvent of quaternary ammonium hydroxide aqueous solution such as tetrabutyl ammonium hydroxide(TBAH).Fundamental characterizations by XRD and SEM were conducted for the nano-ZnO.By controlling experimental conditions,exclusive sphere-like,sheet-like,rod-like or multipod-like microcrystals could be synthesized in a very short period of time.The growth process of nano-ZnO samples was simply analysed.The results indicated that the large quaternary ammonium cation played an important role in the crystal growth process,and the particle size of nano-ZnO decreased with increasing concentration of quaternary ammonium base,concentration of OH-or with decreasing concentration of Zn(OH)42-.国家重点基础研究发展计划(973)项目(2011CBA00508
山西省的鹟科鸟类
(翁鸟)科(Muscicapidae) 鸟类,主要由食虫鸟类组成,因此与农、林业有较密切的关系。研究本科鸟类的生态和分布,不仅是整个鸟类学研究的一个重要组成部分,有重要的学术价值,而且对于合理保护和利用本科鸟类资源,提高农、林业生产的经济效益,改善生态环境质量有不容忽视的实践意义。关于山西省(翁鸟)科鸟类的研究,历史上外国学者清栖幸保(1943;1958—1959)曾在太原等地做过调查,采获本科鸟类不多
design and realization of high performance-cost radio ethernet sip phone with stun support
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