MEASUREMENT OF SPONTANEOUS EMISSION BRANCHING RATIOS IN MO(I) TRANSITIONS BY LASER-INDUCED SENSITIZED FLUORESCENCE

I. TNTRODUCTIONThe emission spectroscopic method is usually used to measure spontaneous emission branching ratios. As emission spectra cannot be detected in atomic beams, the laser-induced fluorescence or ion detection method is often used. When the fluorescence method is used to measure branching ratios, it is usually necessary to detect

Extraction behavior of Mo and W as homologs of Sg with α-benzoinoxime

Solvent extraction of molybdenum and tungsten as homologues of Sg with a-benzoinoxime from HCl solutions has been investigated. The extraction equilibration was achieved at 20s for Mo and W. Molybdenum was almost quantitatively extracted from 0.001 to 4M HCl solutions, and the extraction yields decreased at higher and lower acid concentrations due to the formation of anionic oxychloride complex and anionic species MO42-, respectively. The extraction yield of W was lower than that of Mo during the whole range of acid concentration. The composition of the extracted species was determined by using the slope method in present experiment. The elemental analysis, IR and 1H NMR spectra of the extracted species suggest that the extracted complex contain one MoO22+or WO22+ groups bonded with two a-benzoinoxime molecules.

内蒙古克什克腾旗小东沟斑岩型钼矿床的成矿作用

In this paper, the Xiaodonggou porphyry molybdenum deposit located in the Xarmoron molybdenum metallogenic belt is chose as the research area. We have analyzed the petrology of the Xiaodonggou pluton in detail and made chemical analysis of the major and trace elements, Rb-Sr and Sm-Nd isotope, common lead isotope and SHRIMP zircon U-Pb dating et al; in the other hand, we use the molybdenite to make common lead analysis and Re-Os isotopic dating. The Xiaodonggou pluton is rich in silicon, potass, zirconium, and low in REE. In addition, it has no minus Eu abnormity and show a isotopic composition high in εNd(t) and low in Sri, indicating its magma origining from the melting of juvenile thicken lower crust. In the meanwhile, it contained the features of high temperature, quick melting, quick segregation and quick emplacement. The common lead analysis of the pluton orthoclase and molybdenite show that the former transfer from orogen to mantle and the latter come from mantle, which is consistent to the molybdenite sulfur isotopic and quartz oxygen isotopic composition, demonstrating that the rock and ore-forming materials of deposit having different sources, magma from the lower crust mixing with mantle fluid. In plus, we use the physical experiments results of the water-magma reaction to explain the interaction of magma and mantle fluid. In the deep crust, these two systems uplifted in a immiscible state; when they reached low depth, the stream film between fluid-magma collapsed, and the magma was broken into small agglomerates by the fluid, then they mixed thoroughly. The SHRIMP zircon U-Pb dating gave a result of 142±2Ma and the molybdenite Re-Os dating result is 138.1±2.8Ma, corresponding to the big tectonic transition period of 140Ma, when the major stress field changing from south and north to west and east. At this time, the Da Hinggan ling ranges area was under an extensive background, underplating proceeded and mantle materials could add into the magmas forming in the lower crust. So, from the above analysis, we propose the following model for the Xiaodonggou porphyry molybdenum deposit: in the early Cretaceous period, the Da Hinggan ling ranges area was under a extensive background, the adding of mantle fluid containing ore materials into heated lower crust made it melting to produce magmas. Following more mantle fluid got into the magma room and urged the magma to segregate from the source quickly. The fluid and magma uplifted together, when they arrived at shallow depth, the fluid-magma became unstable and the latter was broken into many small agglomerates with fluid connecting them in the interspaces. Because of the H+, K+ and various elements existing in the fluid, it would reacted with the magma and the rock through alteration and ore minerals crystallized out, forming the Xiaodonggou porphyry deposit with disseminated mineralization phenomenon.

高温实验中重金属钼在硅酸盐熔体中的含量研究

This dissertation discusses current status of high temperature and high pressure and focuses on analyzing systematically the solubility of heavy metals in the silicate magma in HTHP experiments. The high temperature study on the content of heavy metal molybdenum in the silicate melts in this dissertation, which is granted, based on the geology mineralization model and the theory of HTHP experiments and combined with mineralization grade and geochemical nature of Mo, discusses the difference of mineralization between mantle plume and aqueous fluids and comes to the conclusions, which are as follows: (1) The content of Mo in the silicate melts is much greater than Mo mineralization grade. The molybdenum ore has the exploitation value when the industrial grade is higher than 0.06%. Mo content in different silicate melts varies because of the concentration of SiO2, that is, Mo content in the granodiorite is greater. (2) The content of Mo, which varies with reaction time, arises first and drops down in the alkali basalt melts, while variation is not too obvious in the granodiorite melts on the whole. (3) According to the picture of sample, the conclusion is not reached very well on some issues, such as the volatility and characteristic of molybdenum oxide and dependence on the geology environment.

河南小秦岭大湖金－钼矿床地球化学及其矿床成因

秦岭造山带是华北与扬子两大古板块的接合带，在空间上，自北而南，秦岭造山带可分为华北板块南缘（华熊地块）、北秦岭造山带、南秦岭造山带和扬子板块北缘等4个构造单元。小秦岭金矿田位于华熊地块北缘，是国内外学者共识的造山型金矿田，河南灵宝大湖金－钼矿床位于小秦岭金矿田，属断控脉状矿床。大湖金－钼矿床最先正是以金矿床进行勘查的，其黄金储量28t，平均品位8.7g/t。随着开采深度的加大，部分含金石英脉向深部转变为辉钼矿－石英脉，目前探明钼资源量已达中型规模。 本论文主要从区域地质背景、矿床地质特征、元素地球化学、同位素地球化学、流体包裹体地球化学、矿床年代学及成矿机理等角度对大湖金－钼矿床进行了较为系统的研究，主要获得如下认识： 成矿过程经历3个阶段：早阶段为黄铁矿-石英脉，遭受变形、破碎，应形成于挤压或压剪过程；中阶段为细粒的辉钼矿-黄铁矿-石英网脉，贯入到早阶段黄铁矿或石英矿物的裂隙（可呈共轭状），应形成于剪切环境；晚阶段石英-碳酸盐细脉具梳状构造，充填于张性或张扭性裂隙。 大湖金-钼矿床的金属硫化物ISr=0.70470-0.71312，平均0.70854；(143Nd/144Nd)i=0.51143-0.51215，平均0.51162；(206Pb/204Pb)i=17.033-17.285，(207Pb/204Pb)i=15.358-15.438，(208Pb/204Pb)i = 37.307-37.582。其围岩太华群样品平均值ISr＝0.72294，(143Nd/144Nd)i=0.51107，(206Pb/204Pb)i=17.127-18.392，(207Pb/204Pb)i =15.416-15.604，(208Pb/204Pb)i=37.498-37.814，它们的平均值分别是17.547，15.470，37.616。通过金属硫化物及围岩太华群的对比，可以看出，成矿物质具有太华群和深部地幔混合的特征。 通过对不同阶段的含矿石英脉中的流体包裹体特征研究表明，早阶段只发育CO2-H2O型流体包裹体；中阶段流体包裹体类型复杂，有纯CO2型、CO2-H2O型、H2O-NaCl型和含子晶包裹体，指示流体沸腾作用强烈；而晚阶段只发育水溶液包裹体。早、中、晚3个阶段的流体包裹体均一温度分别集中在400-500℃、290-470℃、220-260℃；估计的早、中阶段流体的最低捕获压力分别为138-331MPa和78-237MPa，对应于成矿深度分别为13.8-11.0km和7.8-8.0km。早、中阶段的压力反应出静岩压力到静水压力的转变。成矿温度和压力明显高于浅部含金石英脉的成矿温度120-310℃，成矿压力100-150MPa。与野外观察到的“上金下钼”的空间关系一致。 大湖金－钼矿床辉钼矿－石英脉Re-Os同位素模式年龄较集中，介于215.4±5.4－255.6±9.6Ma，Re-0s等时线年龄为218±41Ma(MSWD=38，2σ误差)，表明大湖金－钼矿的辉矿化形成于印支期。 三叠纪末，随着古秦岭洋的逐渐封闭，处在弧后转换带的深部岩石在挤压作用下发生变质脱水而形成初始成矿流体，成矿流体沿断裂带（韧性剪切带）向上迁移而引起大湖钼矿床成矿系统的发育。随着区域构造环境由挤压转为伸展，区域的变质脱水更强，形成大量成矿流体，变质流体上侵为浅层流体循环提供了的热能，而浅层构造也因减压扩容而为流体循环提供了通道，这无疑有利于浅层流体循环和混入成矿系统。同时，增温和减压也有利于成矿流体发生沸腾。因此，充足的流体、热以及强烈的流体沸腾等，势必导致发生最为强烈的成矿物质快速沉淀作用。随着挤压作用的减弱，伸展作用的增强，区域热异常消失，地壳深部组分发生亏损，流体以浅源大气降水占主导，成矿作用迅速衰竭，形成石英-碳酸盐网脉，对成矿作用贡献减弱。总之，通过对大湖金钼矿床研究表明，大湖金钼矿床形成于由挤压转向伸展的构造背景，这与矿床地质的特征一致。

Investigations on the promoting effect of metal oxides on La-V-O catalyst in propane oxidative dehydrogenation

The addition of reducible metal oxides as promoters shows a positive effect on the catalytic behavior of lanthanum vanadate (LaVO4). A C3H6 yield increase of 6.5% is observed at 500 degreesC on molybdenum-promoted LaVO4, which can be attributed to the change of the redox properties, the blocking of the strong oxidation sites of the catalysts and to an increase of the accessibility of the labile oxygen toward the reactant. The influence of the catalyst preparation method and of the Mo loading as well as the additional promoting effect of CO2 in the gas feed was also examined.

Effect of pore ring number of zeolites on catalytic performance of Mo/Zeolite in methane aromatization under non-oxygen condition

The catalytic behavior of Mo-based zeolite catalysts with different pore structure and size, particularly with 8 membered ring ( M R), 10 M R, coexisted 10 and 12 M R, and 12 M R, was studied in methane aromatization under the conditions of SV=1500 ml/(g.h), p=0.1 MPa and T = 973 K. It was found that the catalytic performance is correlated with the pore structure of the zeolite supports. The zeolites that possess 10 MR or 10 and 12 MR pore structure with a pore diameter equal to or slightly larger than the dynamic diameter of benzene molecule, such as ZSM-5, ZSM-11, ZRP-1 and MCM-22, are fine supports. Among the tested zeolite supports, MCM-22 exhibits the highest activity and selectivity for benzene. A methane conversion of 10.5% with benzene selectivity of 80% was achieved over Mo/MCM-22 catalyst. The Mo/ERS-7 catalyst with 8 MR (0.45 nm) does not show any activity in methane dehydro-aromatization, while Mo/JQX-1 and Mo/SBA-15 catalysts with 12 MR pore exhibit little activity in the reaction. It can be concluded that the zeolites with 10 MR pore or coexisted 10 and 12 MR, having pore size equal to or slightly larger than the dynamic diameter of benzene molecule, are fine supports for methane activation and aromatization.

A high coking-resistance catalyst for methane aromatization

Steaming-dealuminated HZSM-5-supported molybdenum catalysts have been found to be high coking-resistance catalysts for methane aromatization reactions; compared with conventional catalysts, they give a much higher selectivity towards aromatics.

XPS and XRD studies of fresh and sulfided Mo2N

Mo surface species of molybdenum nitride and their changes under sulfiding conditions were investigated by XRD and XPS. Mo2N was synthesized by temperature-programmed reaction of MoO3, with NH3. The decomposition of the Mo3d spectra gave a Mo3d doubler which corresponded to Modelta+ (2 less than or equal to delta < 4), Mo4+ and Mo5+ Or Mo6+ species. The BE of the Mo species of passivated Mo2N shifted to higher energy level compared with the freshly prepared Mo2N due to the oxidation of Mo nitride during passivation. When Mo2N was contacted for 4 h with a 15% H2S-H-2 mixture at 400 degrees C, the XRD spectra did not reveal any new phase, which indicates a high stability of Mo2N against sulfidation, but XPS data showed the presence of sulfur, including S-0 and S2- species, and a decrease of the N/Mo atomic ratio revealed some changes in surface composition. More than one monolayer of Mo2N was transformed to sulfide. It is probable that the oxygen incorporated during passivation reacted with sulfur and formed a thin layer of molybdenum sulfide on the Mo2N surface. (C) 1998 Elsevier Science B.V. All rights reserved.

Simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene over dimolybdenum nitride catalysts

A series of unsupported dimolybdenum nitride (gamma-Mo(2)N) catalysts differing in surface area were prepared by temperature programmed reduction of MoO(3) with a mixture of NH(3):N(2) (90:10). Characterization of catalysts by BET, XRD, TPR and XPS techniques was carried out. The samples were used as catalysts in hydrotreating reactions (simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene). Low surface area gamma-Mo(2)N materials show much higher specific conversions than those with higher surface area. These results indicate that HDS and HYD reactions over gamma-Mo(2)N seem to be structure-sensitive. The relative exposure extent of crystalline planes (111) and (200) over the different catalysts can be associated with their hydrogen adsorption capacities and with their catalytic performances. The catalytic activities are significantly affected by the catalyst pretreatment conditions. (C) 1999 Elsevier Science B.V. All rights reserved.

The formation of Co2C species in activated carbon supported cobalt-based catalysts and its impact on Fischer-Tropsch reaction

The cobalt carbide (Co2C) species was formed in some activated carbon supported cobalt-based (Co/AC) catalysts during the activation of catalysts. It was found that the activity of Fischer-Tropsch reaction over Co-based catalysts decreased due to the formation of cobalt carbide species. Some promoters and pretreatment of activated carbon with steam could restrain the formation of cobalt carbide.

The synergic effect between Mo species and acid sites in Mo/HMCM-22 catalysts for methane aromatization

The acid properties of Mo/HMCM-22 catalyst, which is the precursor form of the working catalyst for methane aromatization reaction, and the synergic effect between Mo species and acid sites were studied and characterized by various characterization techniques. It is concluded that Bronsted and Lewis acidities of HMCM-22 are modified due to the introduction of molybdenum. We suggest a monomer of Mo species is formed by the exchange of Mo species with the Bronsted acid sites. On the other hand, coordinate unsaturated sites (CUS) are suggested to be responsible for the formation of newly detected Lewis acid sites. Computer modelling is established and coupling with experimental results, it is then speculated that the effective activation of methane is properly accomplished on Mo species accommodated in the 12 MR supercages of MCM-22 zeolite whereas the Bronsted acid sites in the same channel system play a key role for the formation of benzene. A much more pronounced volcano-typed reactivity curve of the Mo/HMCM-22 catalysts, as compared with that of the Mo/HZSM-5, with respect to Mo loading is found and this can be well understood due to the unique channel structure of MCM-22 zeolite and synergic effect between Mo species and acid sites.