导电氧化钼的制备及表征

用金属肼盐热分解法,以钼酸铵为原料,用草酸和肼作为添加剂制备了草酸钼酸肼复合盐,并以此为前驱物在氮气保护下,于760℃热分解制得低价态氧化钼粉末。测定了产品的钼、NH4+的质量分数以及电阻率,并通过DSC-TGA、XRD以及BET比表面积测试等表征手段,考察了肼和草酸添加量,以及前驱物热分解时间和分解温度对产品性状的影响。结果表明,典型产品为MoO2,比表面积25 0m2/g,体积电阻率为0 0477Ω·cm,具有良好的导电性能,可以用作导电粉体材料。     

改性钼镍粉在催化缩酮反应中的应用

用改性钼镍粉作催化剂。催化环己酮与乙二醇进行缩合反应。合成了环己酮乙二醇缩酮产物。通过实验选择出了改性钼镍粉催化缩铜反应的最佳条件:n(环己酮)∶n(乙二醇)=1∶2。环己烷作带水剂,其用量为15mL,催化剂用量为环己酮质量的7%,回流反应时间4h。环己酮乙二醇缩酮的总收率为90.5%。     

Effect of Potassium Doping on the Catalytic Behavior of Mo–V–Sb Mixed Oxide Catalysts in the Oxidation of Propane to Acrylic Acid

Small addition of potassium to a Mo–V–Sb mixed oxide catalyst (previously prepared by hydrothermal synthesis) strongly modifies its catalytic behavior. Thus, while acetic acid is mainly observed in the K-free catalysts, acrylic acid is selectively obtained in K-doped catalysts. In this case, a selectivity to acrylic acid of about 30% is achieved at propane conversions of 30%. This catalytic behavior is apparently not due to modification of the crystalline phases in the K-doped catalysts but to the elimination of the acid sites of the undoped Mo–V–Sb mixed oxide catalyst.     

Supported Molybdenum Carbides Lie Between Metallic and Sulfided Catalysts for Deep HDS

Hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene on alumina-supported Mo₂C has been studied. These catalysts are stable and active under deep HDS conditions (0-250 wt ppm S). However, although they are well known to have hydrogenation properties, they lead preferentially to a non-hydrogenated product of the HDS reaction: dimethylbiphenyl. For the same reaction, supported platinum and sulfided molybdenum oxide lead to the hydrogenated products dimethyldicyclohexyl and methylcyclohexyltoluene, respectively. The ranking of HDS activity is as follows: MoS₂/Al₂O₃ < Mo₂C/Al₂O₃ < Pt/SiO₂.     

Effect of Addition of Oxides on Low-Temperature Oxidation of Molybdenum Disilicide

A type of aluminosilicate that has a good wetting property for molybdenum disilicide (MoSi₂) was added to a MoSi₂ matrix to study the effects on the microstructure and low-temperature oxidation. It was found that the composites had not only good low-temperature oxidation resistance but also high thermal shock resistance when the added oxides formed a network microstructure in the matrix. There was no appreciable oxidation gain for MoSi₂/oxide composites with a network microstructure at 773 K for 2500 h. The results indicate that microstructure design is a simple and effective solution to preventing the low-temperature oxidation of MoSi₂.     

Adsorption and separation of rhenium(VII) using N‐methylimidazolium functionalized strong basic anion exchange resin

BACKGROUND: Rhenium is a rare and valuable metal coexisting with molybdenum in molybdenite and sulfide copper ores and is hard to separate. Methods such as solvent extraction, ion exchange, adsorption, precipitation, etc. have been used to separate and purify Re(VII), and resin ion exchange has been widely investigated and used owing to its convenient operation and relatively low‐cost. The main challenge comes from the preparation of resins having high performance and stability. In an earlier study, an N‐methylimidazolium functionalized strong basic anion exchange resin was successfully synthesized and used for Cr(IV) extraction. This paper, reports on further synthesis and application of this resin for adsorption and separation of Re(VII) and Mo(VI), especially from copper arsenic filter cake. RESULTS: At pH 6.25, Re(VII) and Mo(VI) can be effectively separated with the N‐methylimidazolium functionalized strong basic anion exchange resin, giving a Re(VII) recovery of up to 93.3%, but only 5.1% for Mo(VI). When using the copper arsenic filter cake sample 89.1% Re(VII) recovery was achieved. CONCLUSION: The N‐methylimidazolium functionalized strong basic anion exchange resin exhibited high selectivity and recovery for Re(VII) in a mixed system. © 2012 Society of Chemical Industry     

铁钼法甲醛工艺中甲醇转化率低的原因及改进

介绍了河南开祥化工有限公司引进美国DBW铁钼氧化法生产甲醛的工艺,从空气质量、催化剂、氧含量、空速、反应温度、吸收水pH、甲醇雾化率等方面,分析了甲醛生产过程中甲醇转化率低的原因,并总结了实际生产中提高甲醇转化率的方法:控制工艺操作参数、保证催化剂装填质量、注意催化剂的保护等。     

Pebax/a-MoS2/MIP-202混合基质膜的制备及CO2分离性能

为了获得高性能的CO₂/N₂分离膜,把空气中氧刻蚀的二硫化钼（a-MoS₂）和金属有机框架材料MIP-202通过机械力化学反应制备的双功能填料作为分散相,聚醚嵌段酰胺（Pebax-1657）作为连续相,采用溶液浇铸法制备了Pebax/a-MoS₂/MIP-202混合基质膜。采用FT-IR表征了填料的化学结构,借助ATR-FTIR、SEM、TG和力学性能测试表征了混合基质膜的化学结构、微观形貌结构、热稳定性和物理力学性能。研究了水含量、双功能填料配比、含量、膜两侧压差和操作温度对膜气体分离性能的影响,并考察了模拟烟道气（CO₂/N₂体积比15/85）条件下混合基质膜的长时间运行稳定性。结果表明：在温度为25℃、膜两侧压差为0.1 MPa的操作条件下,a-MoS₂与MIP-202质量比为5∶5和双功能填料含量为6%（质量）时,膜的气体分离性能达到最优,CO₂渗透性和CO₂/N₂选择性分别为380 Barrer和124.7,超过了2019年McKeown等提出的上限值。连续测试360 h后,混合基质膜的性能没有明显降低,其平均CO₂渗透性和CO₂/N₂选择性分别为358 Barrer和120.1。这主要是由于a-MoS₂和MIP-202协同提高了膜的气体分离性能。     

Combining molybdenum carbide with ceria overlayers to boost Mo/CeO2 catalyzed ammonia synthesis

The design of an efficient non-noble metal catalyst is of burgeoning interest for ammonia synthesis. Herein, we report a Mo₂C/CeO₂ catalyst that is superior in ammonia synthesis activity. In this catalyst, molybdenum carbide coexisted with the ceria overlayers which is from the ceria support as the strong metal–support interaction. There is a high proportion of low-valent Mo species, as well as high concentration of Ce³⁺ and surface oxygen species. The presence of Mo₂C and CeO₂ overlayers not only leads to enhancement of hydrogen and nitrogen adsorption, but also facilitates the desorption and exchange of adsorbed species with the gaseous reagents. Compared with the Mo/CeO₂ catalyst prepared without carbonization, the Mo₂C/CeO₂ catalyst is more than sevenfold higher in ammonia synthesis rate. This work not only presents an explicit example of designing Mo-based catalyst that is highly efficient for ammonia synthesis by tuning the adsorption and desorption properties of the reactant gases, but opens a perspective for other elements in ammonia synthesis.     

钥钒硅杂多配合物的研究

本文对钼钒硅杂多配合物进行了系统的研究,指认了振动光谱中某些特征谱带.对振动光谱,UV光谱,~(51)V NMR谱的特性进行了探讨,同时利用X-射线粉末衍射,IR光谱、差热-热重分析等手段研究这一系列钼钒硅杂多配合物的热解性质,其热稳定顺序为: K_5SiMo_(11)VO_(40)·mH_2O>H_5SiMo_(11)V_(40)·mH_2O>K_6SiMo_(10)V_2O_(40)·mH_2O>K_7SiMo_9V_3O_(40)·mH_2O