Sample container, vanadium

The catalytic results obtained with the sample containing vanadium, Ki(NH4)3PMoiiViO40, are reported in Table 1, too. 

In the case of titania-pillared samples containing vanadium deposited onto calcined pillars (V-(Ti-PILC)-IA, V-(Ti-PILC)-IB, V-(Ti-PILC)-IC) the activity of nitrile formation increases with V content (Fig. 3) Comparison with the behaviour of the V-(Ti)-PILC sample containing vanadium introduced on uncalcined pillars shows that CN bands of similar intensity are formed for similar levels of doping, in agreement with the ESR data showing the same type of spectra... 

An interest has been developed in the use of vanadium naphthenates as accelerators. In 1956 the author found that if MEKP was added to a polyester resin containing vanadium naphthenate the resin set almost immediately, that is, while the peroxide was still being stirred in. Whereas this effect was quite reproducible with the sample of naphthenate used, subsequent workers have not always obtained the same result. It would thus appear that the curing characteristics are very dependent on the particular grade of resin and of vanadium naphthenate used. It was also observed by the author that the gelation rate did not always increase with increased temperature or accelerator concentration and in some instances there was a retardation. Subsequent workers have found that whilst the behaviour of the naphthenate varies according to such factors as the resin and catalyst used, certain vanadium systems are of value where a high productivity in hand lay-up techniques is desired. 

Two polarographic methods have been developed for the determination of cohalt(II) at concentrations ranging from approximately 1 to 80 mM in an aqueous sample. For the first method [15], which is suitable for samples containing large amounts of nickel]11), the cobalt(II) is oxidized to Co(NH3)6 in an ammoniacal medium with the aid of sodium perborate, after which the cobalt(III) species is determined. A second procedure [16] entails the use of lead dioxide in an acetic acid-acetate buffer containing oxalate to convert cobalt(II) to the 0(0204)3 ion, which can be subjected to polarographic reduction. This latter approach is well suited to the determination of cobalt in the presence of copper(II), iron(III), nickel(II), tin(IV), and zinc(II), whereas the chief interferences are cerium, chromium, manganese, and vanadium. 

An unusual concentration of vanadium was found in the upper part of bed 9 of western Kentucky and in two samples of its correlative bed 5 of Illinois (20). The distribution of the columnar samples from this bed is shown in Figure 9. The dashed line delineates areas where samples contain high vanadium values. 

Vanadium and Pseudo-Boehmite Alumina. The 79 MHz wideline NMR spectra of these steam aged samples containing only 0.5 to 5.0% V (loaded using VO -Naphthenate) are shown in Figure 1. Two... 

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned in utility boilers. Coal ash in the atmosphere also contains vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m3, whereas air samples from Los Angeles and Honolulu contained 1—12 ngV/m3. Adverse public health effects attributable to vanadium in the ambient air have not been determined. Increased emphasis by industry on controlling all plant emissions may have resulted in more internal reclamation and recycle of vanadium catalysts. An apparent drop in consumption of vanadium chemicals in the United States since 1974 may be attributed, in part, to such reclamation activities. 

Samples of used residue hydrodemetallization catalysts prepared by hydrotreating a Safanyia atmospheric residue have been characterized and tested using model compounds in order to investigate the initial deactivation of the catalyst Samples containing 4 to 10 wt % carbon and less than 200 wt ppm V or 10 to 15 wt % carbon and 1.3 wt % V have been obtained from tests in batch and continuous flow reactors respectively. It is shown that in the early stage of the catalyst deactivation a small amount of vanadium is more deactivating than a large amount of carbon. 

The used catalysts of the TS series contain low metal contents. However in view of the possible deactivating effect of 0.7 or 1.3 wt % of vanadium, samples containing even less vanadium were required. These samples have been prepared in batch reactor where the catalyst/oil ratio determines the maximum amount of metal deposited. In this work, with a catalyst/oil ratio of 0.4 and an the SAR containing 106 wt ppm Ni + V, the maximum amount of metal which could be deposited on the catalyst surface is 265 wt ppm Ni + V. ... 

Since EPR spectra of reasonable quality can be obtained on samples containing as little as 20 pM vanadium, studies of VOz+ in tissues and subcellular fractions are possi-... 

If b+ and b- are of different sign [e.g., H, V) there is a small coherent cross section and a large incoherent cross section. For this reason vanadium is used as a ccilibrant in incoherent scattering cross-section measurements (see below) and as a sample container (for polycrystaUine materials) for many of the experiments described below so that unwanted peaks are not introduced into the diffraction pattern. On the other hand, if an element has one isotope of zero nuclear spin in large abundance the scattering is almost entirely coherent [e.g., 0, Fe). 

Pankratz et al. (1 ) measured the enthalpy of combustion of vanadium subnitride at 303.15 K. The composition of their sample was VNq which corresponds to the nitrogen-rich boundary of the subnitride phase (see Phase Data section). Chemical analysis also showed that the sample contained 0.74 weight percent VO and trace amounts of CaO and Mo as impurities. The composition of... 

Parameters of Che iron containing phases of fresh and used samples of vanadium oxide catalysts... 

The simplest method of decomposing an organic sample prior to determining the cations it contains is to heat the sample over a flame in an open dish or crucible until all carbonaceous material has been oxidized to carbon dioxide. Red heat is often required to complete the oxidation. Analysis of the nonvolatile components follows dissolution of the residual solid. Unfortunately, there is always substantial uncertainty about the completeness of recovery of supposedly nonvolatile elements from a dry-ashed sample. Some losses probably result fiom the entrainment of finely divided particulate matter in the convection currents around the crucible. In addition, volatile metallic compounds may be lost during the ignition. For example, copper, iron, and vanadium are appreciably volatilized when samples containing porphyrin compounds are ashed. 

Two procedures are described whereby either the sample is treated with acid to decompose the organic material and dissolve the metals or, alternatively, the sample is dissolved in an organic solvent. The first method is sensitive down to about 1 ppm the precision statement is based on samples containing 1-10 ppm iron, 10-100 ppm nickel, or 50-500 ppm vanadium... 

Binary vanadium-titanium oxide catalysts with various ratios of vanadium oxide and titania, as well as individual oxides of vanadium and titanium were examined in oxidation of P-picoline. Nicotinic acid, 3-pyridinecarbaldehyde, and CO2 were the reaction products over all the catalysts. The binary catalysts and individual vanadium oxide were highly selective for nicotinic acid, the most effective in P-picoline oxidation were the samples containing 20% and more of vanadium pentoxide. A regular stacking of crystallites of V2O5 and Ti02 was found to be the characteristic feature of the structure of the most effective compositions. 

The obtained XRD data (see the Table) showed the anatase phase alone in the samples containing less than 20% of vanadium oxide. The phases of anatase and V2O5 are detected in the catalysts at higher concentrations of V2O5. 

IR spectrum of individual titania and the IR spectra of the binary catalysts coincide well with the spectrum of anatase [8] at 200-1300 cm". However in the spectra recorded for individual Ti02 and the sample containing 5% of vanadium oxide, the maxima of broad absorption bands (a.b.) at 540 and 342 cm", which are characteristic of anatase, are shifted downfield to 517 and 332 cm , at the same time a.b. at 965 and 1050 cm with 1070 and 1125 cm shoulders, respectively, are observed, that indicates the presence of sulfate-ion... 

Fig. 2 (a, b) presents micrographs of samples containing 5% (a) and 20% (b) of vanadium oxide. Identical images were obtained for the samples before and after the reaction. Highly... 

Sample containers are thin-walled cells of either aluminium or vanadium. Vanadium is required if diffraction measurements are to be included. Solids can be simply wrapped in aluminium foil. Liquids, however, must be held in sealed cans. Indium wire provides a good seal, because it is ductile, easily created and, more importantly, it has a very low coefficient of thermal expansion. Thus a can that is sealed at room temperature will remain sealed after having been cycled to 20K. If the compounds are air or moisture sensitive (solid or liquid) they are loaded into the cans in a glove-box. Gases are more problematic, one successful method is have a suitable volume of the gas attached above the cell. The whole is lowered into the cryostat where the gas is first liquefied and allowed to fill the cell, subsequently the temperature is lowered to freeze the liquid. 

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