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Showing papers on "Molybdenum published in 1979"


Journal ArticleDOI
TL;DR: In this paper, the Raman and UV spectra indicated that adsorption on the alumina surface occurred in all cases via the MoO/sub 4/(-2) ion, probably due to locally increased pH.
Abstract: Catalysts containing 1, 3, and 8Vertical Bar3< molybdena on ..gamma..- or g-alumina were prepared by impregnating the support with (NH/sub 4/)/sub 6/Mo/sub 7/O/sub 24/ at pH 6 or 11, at which pH's molybdenum is in the octahedral Mo/sub 7/O/sub 24/(-6) form or the tetrahedral MoO/sub 4/(-2) form, respectively. The Raman and UV spectra indicated that adsorption on the alumina surface occurred in all cases via the MoO/sub 4/(-2) ion, probably due to locally increased pH. The removal of water during drying and calcination caused polymerization of the isolated tetrahedral molybdenum species into a two-dimensional Mo-O-Mo structure. The degree of polymerization depended on the molybdenum concentration, the heat treatment, and the pH of the original adsorption which influences the molybdenum distribution. The coordination number of the molybdenum in the polymeric structure, which was probably affected by the alumina surface hydroxyl density and distribution, could not be determined. Some bulk molybdenum trioxide was formed on all samples after calcination except for a 3Vertical Bar3< MoO/sub 3/ sample impregnated at pH 11.

359 citations


Book
01 Jun 1979
TL;DR: In this article, a few moment to read a book even only few pages is recommended, even if it is not obligation and force for everybody, reading book becomes a choice of your different characteristics.
Abstract: Spend your few moment to read a book even only few pages. Reading book is not obligation and force for everybody. When you don't want to read, you can get punishment from the publisher. Read a book becomes a choice of your different characteristics. Many people with reading habit will always be enjoyable to read, or on the contrary. For some reasons, this molybdenum and molybdenum containing enzymes tends to be the representative book in this website.

294 citations


Journal ArticleDOI
TL;DR: In this paper, the correlation between composition of surface films and the beneficial effects of molybdenum addition to high purity, 30Cr ferritic stainless steels in improving the corrosion resistance properties in HCI was investigated.

251 citations


Journal ArticleDOI
TL;DR: In this paper, a large body of published data is combined with their own observations to construct maps for a number of polycrystalline metals and ceramics: the refractory b.c.p. metals: tungsten, molybdenum, tantalum, niobium and chromium.

245 citations


Patent
11 Apr 1979
TL;DR: In this article, a plated deposit in an electroless nickel plating bath containing an ester complex of a polyhydric acid or alcohol such as the diboron ester of glucoheptonic acid is described.
Abstract: Electroless, polymetallic nickel alloys containing an element of boron or phosphorus and one or more metals selected from tin, tungsten, molybdenum or copper which have unique properties and are produced as a plated deposit in an electroless nickel plating bath containing an ester complex of a polyhydric acid or alcohol such as the diboron ester of glucoheptonic acid.

187 citations


Patent
28 Jun 1979
TL;DR: In this article, a polar solvent, an acidic molybdenum compound and an oil-soluble basic nitrogen compound are combined with carbon disulfide to form a sulfur-containing composition.
Abstract: Antioxidant additives for lubricating oil are prepared by (1) combining a polar solvent, an acidic molybdenum compound and an oil-soluble basic nitrogen compound to form molybdenum-containing complex and (2) contacting said complex with carbon disulfide to form a sulfur-and molybdenum-containing composition.

158 citations


Journal ArticleDOI
TL;DR: The surface of molybdenum metal was examined by XPS after exposure to gaseous and liquid systems and after electrochemical treatment as discussed by the authors, the latter being conducted in a specially designed electrochemical cell situated in a vacuum chamber attached to the main spectrometer chamber.

146 citations


Patent
28 Jun 1979
TL;DR: In this paper, an antioxidant additive for lubricating oil is prepared by combining an acidic molybdenum compound, an oil-soluble basic nitrogen compound and carbon disulfide to form a sulfur-and moly bdenum-containing composition.
Abstract: Antioxidant additives for lubricating oil are prepared by combining an acidic molybdenum compound, an oil-soluble basic nitrogen compound and carbon disulfide to form a sulfur-and molybdenum-containing composition.

139 citations


Journal ArticleDOI
TL;DR: Molybdenum cofactor activity was found in the soluble fraction of cell-free extracts of Escherichia coli grown aerobically in media supplemented with molybdate, and cofactor was detected by its ability to complement the nitrate reductase-deficient mutant of Neurospora crossa, nit-1, resulting in the vitro formation of nitrate reducesase activity.
Abstract: Molybdenum cofactor activity was found in the soluble fraction of cell-free extracts of Escherichia coli grown aerobically in media supplemented with molybdate Cofactor was detected by its ability to complement the nitrate reductase-deficient mutant of Neurospora crossa, nit-1, resulting in the vitro formation of nitrate reductase activity Acid treatment of E coli extracts was not required for release of cofactor activity Cofactor was able to diffuse through a membrane of nominal 2,000-molecular-weight cutoff and was insensitive to trypsin The cofactor was associated with a carrier molecule (approximately 40,000 daltons) during gel filtration and sucrose gradient centrifugation, but was easily removed from the carrier by dialysis The carrier molecule protected the cofactor from inactivation by heat or oxygen E coli grown in molybdenum-free media, without and with tungsten, synthesized a metal-free "empty" cofactor and its tungsten analog, respectively, both of which were subsequently activated by the addition of molybdate Empty and tungsten-containing cofactor complemented the nitrate reductase subunits in the nit-1 extract, forming inactive, but intact, 79S nitrate reductase Addition of molybdate to the enzyme complemented in this manner restored nitrate reductase activity

129 citations


Journal ArticleDOI
TL;DR: In this article, the formation of supported molybdate catalysts was investigated using laser Raman spectroscopy, and the effect of variations in the preparation procedure was investigated.

125 citations


Patent
28 Jun 1979
TL;DR: In this paper, a polar promoter, an acidic molybdenum compound and a basic nitrogen compound are combined to form a mixture of the polar promoter and the acidity of the nitrogen compound.
Abstract: Antioxidant additives for lubricating oil are prepared by combining a polar promoter, an acidic molybdenum compound and certain basic nitrogen compound to form a molybdenum-containing compositions.



Journal ArticleDOI
TL;DR: In this article, extended x-ray absorption fine structure (EXAFS) data indicate that reduced xanthine oxidase contains molybdenum in the four valence oxidation state.
Abstract: Xanthine oxidase was isolated from unpasteurized buttermilk by a standard procedure. Extended x-ray absorption fine structure (EXAFS) data indicate that reduced xanthine oxidase contains molybdenum in the four valence oxidation state. Curve fitting of the EXAFS data for oxidized xanthine oxidase suggests that there are two different Mo-ligand distances, 1.5 oxygen atoms at 1.71 A and 2 sulfur atoms at 2.54 A. Including a third sulfur atom at a longer distance significantly improved the fit. Several possible formulations are proposed. 2 figures, 1 table.

Journal ArticleDOI
TL;DR: In this article, the surface enrichment of chromium and molybdenum during dissolution of Fe18Cr (110) and Fe18c3Mo (110), at constant potentials in the passive region is elucidated by taking into account quantitative information on partial dissolution rates of alloy components as measured by γ-spectrometry and on chemical composition of passivating films.

Journal ArticleDOI
TL;DR: In this article, a detailed structural model for the sulfite oxidase molybdenum site was proposed by correlating the Mo K-absorption edge changes with a variety of model compounds, and curve fitting the x-ray absorption fine structure data with previously determined phase shift and amplitude functions.
Abstract: The results indicate both oxo and sulfur coordination for the molybdenum in this enzyme. By correlating the Mo K-absorption edge changes with a variety of model compounds, and by curve fitting the x-ray absorption fine structure data with previously determined phase shift and amplitude functions, a detailed structural model for the sulfite oxidase molybdenum site may be proposed. It was conducted that the Mo in sulfite oxidase is bound to a mixture of oxo- and sulfur-donor ligands. 2 figures, 1 table.






Journal ArticleDOI
TL;DR: In this paper, the composition of surface films formed on 19Cr and 19Cr-2Mo ferritic stainless steels in 1N HCl has been analyzed by X-ray photo-electron spectroscopy.


Journal ArticleDOI
TL;DR: In this article, the surface structure, the environment and the distribution of the active sites of fixed Mo catalysts were spectroscopically investigated and compared with those of conventional catalysts made by an impregnation method.
Abstract: The surface structure, the environment and the distribution of the active sites of fixed Mo catalysts were spectroscopically investigated and compared with those of conventional catalysts made by an impregnation method. The fixed catalysts were found to have the tetrahedral dioxostructure of six-valent molybdenum with coordination unsaturation, uniformly and atomically populated at silica or alumina surface, in a different environment from that of the impregnation catalysts. Such properties of molybdenum are thought to be essential factors for catalytic action in the abstraction of a hydrogen atom(hydride) from the C—H bond of a reactant. There are three different types of molybdenum species in the impregnation silica catalysts.

Journal ArticleDOI
TL;DR: Laser-raman spectroscopy of the alumina-supported rhenium oxide metathesis catalyst was performed in this article, and it was shown that rhenia is present as a single species, consisting of tetrahedrally coordinated ReO(-1) ions which are dynamically distored by the carrier or surface hydroxyl ions.


Journal ArticleDOI
TL;DR: In this article, the effect of molybdenum in amorphous Fe-Mo-PP-C alloys was investigated through the composition of surface film analyzed by XPS.

Journal ArticleDOI
TL;DR: In this article, single-crystal x-ray diffraction has been completed for two compounds: (1) SCH/sub 3/; and (2) X = N(CH/ sub 3/)/sub 2/. Bond angles and bond lengths are given.
Abstract: Single-crystal x-ray diffraction have been completed for these two compounds: (1) X = SCH/sub 3/; and (2) X = N(CH/sub 3/)/sub 2/. Bond angles and bond lengths are given. The x-ray absorption fine structure (EXAFS) analysis of 1 and 2 are compared with the spectra of oxidized forms of xanthine oxidase and sulfur oxidase. Curve fitting analysis of the data, in their oxidized forms, both enzymes contain the MoO/sub 2//sup 2 +/ unit. The average M=O distances, 1.71 A, are the same for both proteins. Sulfur atoms are present at average distances of 2.42 and 2.54 A for sulfite and xanthine oxidase, respectively. A more distant sulfur is present in both enzymes at 2.85 A. Similarities in the EXAFS spectra for 1 and sulfite oxidase Mo--O and Mo--S bond lengths are apparent. Comparisons of the Mo--S distances in the enzymes with those of 1 and 2 suggests configurational features about the molybdenum sites in the enzymes. The thiolate sulfurs in 1 and 2 are trans to each other and cis to the oxo groups with the Mo--thiolate distances all between 2.40 and 2.42 A. The distances are consistent with other known structures containing thiolates cis to Mo=O. Sulfite oxidase hasmore » similar Mo--S distances, but in xanthine oxidase a longer distance (2.54 A) is observed. Since a pronounced trans effect is known to exist for M=O bonds, this longer distance may be characteristic of a thiolate sulfur trans to a Mo--O. 2 figures, 1 table.« less

Journal ArticleDOI
TL;DR: In this article, substitution reactions of PhMn(CO)5 and η5-C5H5M (CO)3X complexes with arsines and phosphines were performed at room temperature in the presence of (CH3)3NO.

01 Jan 1979
TL;DR: Fifty-six papers were presented at the Climax Third International Conference on the Chemistry and Uses of Molybdenum as discussed by the authors, which highlighted the tremendous importance of the use of molybdates and oxides in industrial catalytic applications.
Abstract: Fifty-six papers were presented at the Climax Third International Conference on the Chemistry and Uses of Molybdenum The tremendous importance of the use of molybdenum compounds in industrial catalytic applications is highlighted in these proceedings The structure and resultant catalytic activity of molybdates and oxides is detailed for the varied reactions of hydrodesulfurization, selective oxidation and oxidative dehydrogenation The future role that molybdenum compounds will play in coal liquefaction is also stressed; molybdenum catalysts appear to be an essential ingredient in the US energy self-sufficiency program New insights into fundamental molybdenum chemistry are provided by research directed towards the electronic structure and the thermochemical strength of molybdenum-molybdenum bonds The synthesis of new organo-molybdenum compounds and the chemistry of Mo-Mo triple bonds in cyclic compounds is described Model studies of molybdenum enzymes help to illuminate the structure and spectroscopic properties of these compounds Studies of the molybdenum centers in xanthine oxidase, sulfite oxidase and nitrate reductase are reviewed Fifteen papers are abstracted separately