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181.
Catalytic performances of the CO2 reforming of toluene on Co/Mg O catalysts with different cobalt loadings were evaluated in a fluidized-bed reactor. The results showed that the conversion of toluene and the stability of Co/Mg O increased, but the apparent reaction rate decreased at the initial stage with increasing the amount of metallic Co formed from the reduction of Co/Mg O catalysts at 700°C. The deactivation of Co/Mg O catalysts was mainly resulted from that a part of the metallic Co was oxidized by CO2 and could not be re-reduced by H2 at reaction temperature. Therefore, the excess metallic Co on the higher Co loading catalysts was beneficial to the catalyst stability. 相似文献
182.
Yu. A. Borisov 《Russian Chemical Bulletin》2000,49(11):1820-1822
The proton affinity (PA) energies of fluoro derivatives of benzene, toluene, andm-xylene were obtained fromab initio MP2-FC/6-31G* calculations and compared with experimental results. Protonated forms of the molecules, resulting from different ways of
proton addition, were studied. Relative concentrations of isomeric arenonium ions were calculated and compared with the results
of NMR studies on arenonium ions in solutions.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1847–1849, November, 2000. 相似文献
183.
Ultrasonic absorption in binary liquid mixtures containing benzene, chloroform, cyclohexane and toluene with triethylamine,
a rotational isomeric relaxing liquid, as a common component has been studied at a frequency of 7.56 MHz. A pulse techrique
has been used for the measurement of absorption with an accuracy of ±5%. Bauer-Sette formula has been used to calculate the
absorption of these liquid mixtures at different concentrations. The theoretical values evaluated on the basis of Bauer-Sette
theory appear to have good agreement with experimental values. In view of the discrepancy pointed out by Mallikarjuna Rao
and Suryanarayana, the mixtures of benzene and ethylacetate have been studied in this context and found the theoretical values
coinciding with experimental values. 相似文献
184.
Recent developments in manufacturing emulsions and particulate products using membranes 总被引:9,自引:0,他引:9
Membrane emulsification (ME) is a relatively new technique for the highly controlled production of particulates. This review focuses on the recent developments in this area, ranging from the production of simple oil-in-water (O/W) or water-in-oil (W/O) emulsions to multiple emulsions of different types, solid-in-oil-in-water (S/O/W) dispersions, coherent solids (silica particles, solid lipid microspheres, solder metal powder) and structured solids (solid lipid microcarriers, gel microbeads, polymeric microspheres, core-shell microcapsules and hollow polymeric microparticles). Other emerging technologies that extend the capabilities into different membrane materials and operation methods (such as rotating membranes, repeated membrane extrusion of coarsely pre-emulsified feeds) are introduced. The results of experimental work carried out by cited researchers in the field together with those of the current authors are presented in a tabular form in a rigorous and systematic manner. These demonstrate a wide range of products that can be manufactured using different membrane approaches. Opportunities for creation of new and novel entities are highlighted for low throughput applications (medical diagnostics, healthcare) and for large-scale productions (consumer and personal products). 相似文献
185.
整体式催化剂活性组分负载策略及微波催化燃烧甲苯特性 《燃料化学学报》2003,48(9):1140-1152
针对催化剂活性组分脱落问题,采用载体预处理和添加硅溶胶的策略来强化活性组分负载,微波单模腔中催化燃烧甲苯以考察催化剂活性,并对牢固负载的催化剂进行表征分析。研究表明,常温下采用10%盐酸溶液对蜂窝状堇青石(CH)载体预处理、硅溶胶添加量与载体吸水量比值为0.125条件下所制备的Cu-Mn-Ce(硅溶胶)/CH催化剂脱落率为0.0129%,明显低于Cu-Mn-Ce/CH催化剂的0.950%。Cu-Mn-Ce(硅溶胶)/CH催化剂具有更小的活性颗粒尺寸、更大的比表面积和更多样的活性晶体,在甲苯进气浓度1000 mg/m3、进气量0.12 m3/h、微波功率200 W和床层温度350℃条件下,催化剂对甲苯的催化燃烧效率和矿化率分别为98.5%和87.9%;连续实验43 h后,催化剂活性保持稳定且活性组分脱落率低(0.0328%)。硅溶胶的添加增强了活性组分与载体之间的相互作用力,生成的硅氧烷化学键提高了活性组分的结合牢固度。 相似文献
186.
Gas Phase Selective Catalytic Oxidation of Toluene to Benzaldehyde on V2O5-Ag2O/η-Al2O3 Catalyst 总被引:1,自引:0,他引:1
TonglaiZhang LiqiuMao WeihuaLiu 《天然气化学杂志》2004,13(4):238-243
Gas phase selective catalytic oxidation of toluene to benzaldehyde was studied on V2O5-Ag2O/η-Al2O3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM,and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No.4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzalde hydewere higher than those on the undoped catalyst. This was attributed to the disordered structure of V2O5 lattice of the K-doped catalyst and a better interfacial contact between the particles. 相似文献
187.
Because catalysis by metals is a surface phenomenon, many technological catalysts contain small (typically nanometre-sired) supported metal particles with a large fraction of the atoms exposed. Many reactions, such as hydrocarbon hydrogenations, are structure-insensitive, proceeding at approximately the same rates on metal particles of various sizes provided that they are larger than 1 nm and show bulk-like metallic behavior. But the catalytic properties are not known when metal particles become so small that their sizes are indium clusters consisting of several indium atoms. Here the catalytic behavior of precisely defined clusters of just four and six indium atoms on solid supports is shown. It is found that the Ir4 and Ir6 clusters differ in catalytic activity both from each other and from metallic Ir particles. 相似文献
188.
WANG Zhenya HAO Liqing ZHOU Liuzhu GUO Xiaoyong ZHAO Wenwu FANG Li & ZHANG Weijun Laboratory of Environmental Spectroscopy Anhui Institute of Optics Fine Mechanics Chinese Academy of Sciences Hefei China 《中国科学B辑(英文版)》2006,49(3):267-272
Aromatic hydrocarbons are air pollutants in urban atmosphere and mainly from anthropogenic sources, i.e., emission from automotive exhaust and productive process of industry, and they constitute an important fraction of total volatile organic compounds (VOCs). Photochemical ozone and secondary organic aerosols (SOA) could be formed from the photochemical proc- esses of aromatic hydrocarbons. SOA may impact visibility of air, formation of clouds, change of the climate, and human health serio… 相似文献
189.
SMAI和CI法制备的Ni—Ag/SiO2催化剂的结构与催化性质研究 总被引:1,自引:0,他引:1
应用溶剂化金属原子浸渍(SMAI)法和普通浸渍(CI)法制备了金属含量相同的SiO2负载Ni-Ag双金属催化剂。XRD和磁测定结果表明SMAI催化剂中Ni和Ag的粒度均小于金属含量相同的CI催化剂,SMAI催化剂中Ni和Ag未形成合金,而CI催化剂中Ni和Ag形成了合金。SMAI和CI催化剂都具有超顺磁性。研究了这些催化剂在甲苯加氢反应的催化性质,结果表明与组成相同的普通浸渍法催化相比,SMAI催 相似文献
190.