一次溶样法分析电解金属锰中的磷、硅

为提高电解金属锰的检测效率,用硝酸将电解金属锰溶解后定容,分别移取10mL做P、Si的测定,检测结果与标准方法比较误差均在允许范围以内。本方法减少了检测环节,较大地提高了效率。     

分光光度法测定钼精矿中磷

采用王水 氢氟酸 高氯酸溶矿,以5%的HCl浸取,用磷锑钼蓝分光光度法测定钼精矿中的磷。     

磷锑钼蓝光度法测定矿石中的磷

研究了用磷锑钼蓝光度法测定矿石中微量磷的方法。试样经王水分解后,在硫酸介质中用盐酸-氢溴酸挥发排锡、砷、锑,调整硫酸浓度在0.2～0.3 mol/L,加混合显色液后,使磷形成"磷锑钼蓝"杂多酸络合物。试验证明:在50 mL显色液中含5～30μg的磷符合比尔定律,其λmax=700nm,表观摩尔吸光系数为ε=1.64×104,测定范围在10-3～10-1μg/L。     

湿法消解-分光光度法测定成核剂中的磷含量

采用石墨炉湿法消解的方法,将成核剂中的有机磷转化为正磷酸根,用磷钼蓝分光光度法测定含量.磷含量在0～20μg/25mL范围内线性关系良好.选取三种不同成核剂,5次平行测定后,RSD在0.81％到1.86％范围内.本方法与ICP-OES相比较,无显著性差异.     

化学镀镍-磷合金镀层中磷的测定

准确、简便地测定镍-磷合金镀层的磷对化学镀镍工艺具有重要作用.采用浓硝酸退镀镍-磷合金镀层→高锰酸钾氧化→亚硝酸钠还原→加水定容的方法制备实验溶液,然后分别用磷钼钒黄分光光度法、磷钼酸铵容量法分析试液中的磷,再换算出镀层中磷的质量分数,并与标准方法测定结果对比.结果表明:光度法测定的相对误差为7.93％,相对标准偏差为4.38％;容量法测定的相对误差为-1.83％,相对标准偏差为0.82％.容量法具有准确、简便的优点,可在生产实际和实验研究中推广应用.     

水基金属清洗剂中磷的测定

磷铋钼蓝光度法测定水基金属清洗剂中磷量,采用硝酸和高氯酸的混合酸消化试样,在一定的酸度和硝酸铋存在下,磷与钼酸铵生成磷铋钼杂多酸--磷铋钼黄,用抗坏血酸还原磷铋钼黄为磷铋钼蓝,磷的质量浓度为O～6.0mg/L时与吸光度呈线性关系.方法操作简单,分析结果准确,可用于日常检验.     

Site isolation for light hydrocarbons oxidation

From consideration of several examples of catalytic oxide systems, it appears that the mild oxidation of light alkanes to oxygenates is controlled by the local properties of the surface of oxides which favour the isolation of the active cation or of a controlled number of active sites. This appears to be quite general on massic mixed oxides as well as on supported oxides. Two examples are given for n-butane oxidation to maleic anhydride on the VPO catalyst and for ethane oxidation to acetic acid on the VPMoO/TiO₂catalyst. This conclusion was reached by using several physicochemical techniques which are complementary and may distinguish the surface and the bulk properties of the catalytic oxides. As a consequence, the improvement of the performance of a catalytic oxide system and the discovery of new generation of catalysts will stem from the modification at short distance of the local environment of the active site.     

Raman Spectra of Molybednum Phosphate Glasses and Some Crystalline Analogues

The Raman spectra of a series of glasses in the system MoO₃-P₂O₅ and the polyerystalline compounds molybdenum metaphosphate (MoO₂(P0₃)₂) and molybdenum pyrophosphate ((MoO₂)₂P₂O₂) are reported. The spectra indicate that traces of P=O and phosphate chains are present only in glasses having less than 50 mol% MoO₃. Comparison of the glass spectra with spectra of crystalline molybdenum phosphates indicates the presence of metaphosphate and orthophosphate structural groups of MoO₃ concentrations of about 50 mol% or less. As the MoO₃ concentration is increased, the bands characteristic of pyrophosphate groups appear in the spectra and become the dominant feature at 76 mol% MoO₃ concentration. Metaphosphate groups are present in the glass even at the highest MoO₃ concentrations measured.     

Novel phosphorus-doped alumina-supported molybdenum and tungsten carbides: synthesis, characterization and hydrogenation properties

The effect of atomically dispersed phosphorus on Mo₂C- and WC-supported -Al₂O₃ has been studied. Phosphorus was introduced via molybdenum or tungsten heteropolyanions. Mo- and W-based heteropolyanions were used to synthesize supported materials. Propene and tetralin hydrogenation were used as molecular probe reactions to test the activity and selectivity of the alumina-supported molybdenum or tungsten carbides. The effect of phosphorus on the hydrogenation activity of materials was also considered. Catalysts were characterized by X-ray diffraction, transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS) and CO chemisorption. Phosphorus was found to increase significantly the activity of molybdenum and tungsten carbides. Supported molybdenum carbides are highly dispersed. Tungsten carbide particles are well dispersed with sizes ranging from 2 to 4 nm. To check the stability of carbides they were characterized after catalytic runs.     

Vanadium–molybdenum phosphates supported by TiO2 for ethane oxidation to acetic acid: a correlation between the local environment of vanadium and the reactivity

Different complementary physicochemical tools have been used to explain the improvement of the catalytic performances for ethane oxidation into acetic acid induced by the addition of molybdenum as phosphate to vanadium phosphate deposited on TiO₂-anatase, at a coverage below the monolayer. Electron microscopy techniques have shown that the elements are dispersed on the support. Electron spin resonance, laser Raman and UV-visible spectroscopies have evidenced that the short range order around vanadium is modified by the presence of molybdenum. ⁵¹V NMR has shown that molybdenum favours the octahedral symmetry of vanadium. The acidic properties of the catalyst are improved by the adding effect of molybdenum and by the addition of water. This should explain a better desorption of acetic acid and the improvement of the corresponding yield. This confirms the importance of the atomic environment of vanadium-based oxides to control the mild oxidation of light alkanes. This revised version was published online in August 2006 with corrections to the Cover Date.     

Suitability of North Carolina natural phosphate to Polish agriculture

North Carolina Natural Phosphate (NCNP) is a natural marine sediment, excavated, washed and sold in unprocessed form as a phosphate fertilizer. In vegetation and field experiments carried on in Poland in 1992–1994 with potatoes, rye, maize and winter rape the efficiency of phosphorus in NCNP was in the range of 75–100% of phosphorus in superphosphate. Blending and granulating of NCNP with urea and sulphur proved to be very effective. Further works on blending technology and the usability of NPS or NPKS blends are recommended.     

An improved phosphorus assay for oils without carcinogenic hydrazine sulfate

An improved spectrophotometric method for phosphorus determination in oils is proposed. The proposed new method has made significant improvements in safety, sensitivity, and efficiency in comparison with the current American Oil Chemists’ Society (AOCS) Official Method (Ca 12–55, corrected 1992). The AOCS method employs hydrazine sulfate as the reducing agent to generate molybdenum blue. Hydrazine sulfate is a known carcinogen in laboratory animals and a suspected human carcinogen. The chemical also irritates skin and mucous membranes. In the improved method ascorbic acid is used as the reducing agent. Ascorbic acid is equally effective as hydrazine sulfate for the color reaction. The improved method is approximately 75 times more sensitive than the AOCS method. The sensitivity is improved by measuring absorbance at the absorption peak, 825 nm, and reducing the final volume of reaction mixture for color reaction. The AOCS method determines phosphorus by measuring absorbance at 650 nm, which is about 40% of that at the absorption peak. The efficiency of this improved method is also significantly increased by reducing sample size and the volumes of sample preparation. Therefore, the improved method is more cost-effective than the AOCS method because less chemical reagents and smaller glassware are used, and the hazardous chemical waste disposal cost is eliminated. The improved method also avoids concentrated HCl and 50% KOH for sample preparation.     

Fertilizer requirement of rice-wheat and maize-wheat rotations on coarse-textured soils amended with farmyard manure

Field experiments with rice-wheat rotation were conducted during five consecutive years on a coarse-textured low organic matter soil. By amending the soil with 12t FYM ha^–1, the yield of wetland rice in the absence of fertilizers was increased by 32 per cent. Application of 80 kg N ha^–1 as urea could increase the grain yield of rice equivalent to 120 kg N ha^–1 on the unamended soil. Although the soil under test was low in Olsen's P, rice did not respond to the application of phosphorus on both amended and unamended soils. For producing equivalent grain yield, fertilizer requirement of maize grown on soils amended with 6 and 12 t FYM ha^–1 could be reduced, respectively to 50 and 25 per cent of the dose recommended for unamended soil (120 kg N + 26.2 kg P + 25 kg K ha^–1). Grain yield of wheat grown after rice on soils amended with FYM was significantly higher than that obtained on unamended soil. In contrast, grain yield of wheat which followed maize did not differ significantly on amended or unamended soils.     

钼资源回收工艺现状及展望

介绍了钼资源的重要性及其二次资源回收的必要性。以含钼废催化剂、钼酸铵生产废水、钼金属制品废料为例,介绍了回收二次资源中钼的方法。重点对常用的溶剂萃取法、焙烧-碱浸法和离子交换法等进行了详细评述,分析了各种方法的原理和优缺点。最后提出当前回收工艺中存在的问题,特别是焙烧过程中热能的回收和低浓度有毒气体的处理、生产能力的提高及新的污染的解决等。并对该领域未来发展前景进行了展望。     

Effect of phosphate on the sorption,desorption and plant-availability of selenium in soil

Phosphate, applied at 5µg P cm^–3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (X_m) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (G) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm^–3 to 1.0µg Se cm^–3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl₂ solution, more readily extractable to 0.5M NaHCO₃ and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.     

Preparation,characterization, and catalytic behavior of MoRh2O6 supported on SiO2

Rh double-oxide compound (MoRh₂O₆) supported on SiO₂ was prepared by air calcination treatment of a molybdenum oxide-promoted Rh/SiO₂ catalyst at 700 °C, and the chemisorptive and catalytic properties of the compound, as well as the changes in those behaviors by H₂ reduction, have been studied.The MoRh₂O₆/SiO₂ catalyst exhibited almost no ability of H₂ and CO chemisorption, but a high activity for CO oxidation reaction. After H₂ treatment at 200 °C, X-ray diffraction showed that the MoRh₂O₆ compound was reduced to a MoRh alloy, and this catalyst now exhibited a significant activity for the hydrogenolysis of cyclohexane. A drastic decrease in the activity was, however, observed after H₂ treatment at 500 °C.     

硫化二硫代磷酸钼的合成及其性能的研究

研究了硫化氢对合成硫化二硫代磷酸钼（Ｓ—ＭｏＤＴＰ）的产率、产物钼含量及其润滑特性的影响。结果表明，硫化氢可提高合成Ｓ—ＭｏＤＴＰ产率１．０％～２０．０％，增加其钼含量０．４％～１．３％。只要０．５％Ｓ—ＭｏＤＴＰ的添加量，即可使润滑油的摩擦系数降低５４．８％，其磨斑直径减少６０．８％。