Molybdenum sulfide molybdic acid

In 1785 B. Pelletier proved that the ore mineralogists used to call molybdenum is a sulfide of that metal (28). The molybdic acid obtained by Scheele does not exist as such in the mineral, but was produced when he oxidized the molybdenum sulfide with nitric acid. 

Alumina catalysts activated by additions of dehydrogenating catalysts, e.g., nickel oxide, copper oxide or sulfide, zinc oxide or sulfide, cobalt selenide, zinc phosphate, cadmium tungstate, mixtures of the oxides of zinc and tungsten, of cadmium and molybdenum, etc., are claimed to be superior in the formation of acetaldehyde from mixtures of steam and acetylene at 350° to 400° C.l-la Zinc oxide catalysts may be activated in a similar way by the addition of small amounts of molybdates or molybdic acid, and are effective at 300° to 350° C.121b... 

Molybdic acid, sodium salt. See. Sodium molybdate anhydrous Molybdic oxide. See Molybdenum trioxide Molybdic sulfide. See Molybdenum disulfide Molybdic trioxide. See Molybdenum trioxide Molybdophosphoric acid 12-Molybdophosphoric acid. See Phosphomoiybdic acid... 

Hexacarbonylmolybdenum was synthesized in low yields by L. Mond by the reaction of pyrophoric molybdenum with carbon monoxide. Presently, it is prepared by carbonylation of M0CI5, molybdic acid, molybdenum sulfide, and other molybdenum compounds. The following reducing agents may be employed Mg, Al, Na, Zn, Fe, Grignard reagents, aluminum organometallic compounds, etc. Sometimes such syntheses involve dry methods whereby no solvent is used. However, most commonly. 

Molybdenite concentrate contains about 90% M0S2. The remainder is primarily siUca, with lesser amounts of Fe, Al, and Cu. The concentrate is roasted to convert the sulfide to technical molybdic oxide. Molybdenum is added to steel in the form of this oxide. In modem molybdenum conversion plants, the oxidized sulfur formed by roasting M0S2 is converted to sulfuric acid. 

The catalysts are prepared by impregnating the support with aqueous salts of molybdenum and the promoter. In acidic solutions, molybdate ions are present largely in the form of heptamers, [Mo2024] , and the resulting surface species are beHeved to be present in islands, perhaps containing only seven Mo ions (100). Before use, the catalyst is treated with H2 and some sulfur-containing compounds, and the surface oxides are converted into the sulfides that are the catalyticaHy active species. 

I. From molybdenite, the extraction may be made in several ways, (a) The mineral is roasted as long as sulfur dioxide is given off. The residue which contains MoOs is leached with dilute ammonia and the solution evaporated until the ammonium molybdate crystallizes. Japanese patent 37420 (1920) extracts the roasted ore with Na2COj solution, then precipitates calcium molybdate by adding CaCb. (6) The finely ground ore is heated with nitric acid and the MoOj dissolved in ammonia, (c) A current of chlorine is passed over the dry pulverized ore at a temperature of 208°. The molybdenum chloride distills over and may be separated from sulfur and other chlorides by fractional condensation.2 (d) A British patent describes the extraction with an alkaline sulfide or polysulfide solution which removes the molybdenum from the ore as the soluble thio-molybdates. These may be converted to the molybdates by acidification or by contact with more ore. 

Cupric sulfate anhydrous Cupric sulfate pentahydrate Direct brown 95 Ferric ammonium ferrocyanide Ferric chloride Ferric chloride hexahydrate Ferric sulfate Lead chromate oxide Lead molybdate Mercury sulfide (ic), black Mercury sulfide (ic), red Molybdenum trioxide 3-Naphthol Nonoxynol-55 Phosphomolybdic acid... 

When testing for molybdenum in mixtures containing metal salts, it is best to boil the test material with sodium carbonate or to fuse it with potassium sodium carbonate, to form water-soluble alkali molybdate. If a mixture of acid-insoluble sulfides is being tested, the sulfur can be roasted off and the alkali molybdate then dissolved out by digesting with alkali hydroxide. 

---