Ferrous molybdate

Ferrous Molybdate.—The anhydrous normal salt, FeMoOj, is formed by fusing together ferrous chloride, sodium molybdate, and sodium chloride. Molybdates in solution are reduced by the addition of ferrous salts. 

Further kinetic studies of methanol selective oxidation to formaldehyde over ferric and ferrous molybdate bismuth, chromium, aluminum, and heteropoly molybdates, demonstrated that a wide range of metal molybdates are active and selective for this reaction and that the same mechanism of methanol adsorption and reaction occurs [19]. 

One of the most effective elements added to austenitic stainless steel, and for that matter even ferritic stainless steel, in order to improve pitting resistance is Mo [8]. Molybdenum, however, is a highly versatile element, existing in the passive film in a number of oxidation states. In the case of the hexavalent state it has been observed in both the cationic and anionic states, namely as molybdenum trioxide and ferrous molybdate. It has most commonly been reported to exist in the quadrivalent state as molybdenum dioxide and oxyhydroxide. 

The mechanism and rate of hydrogen peroxide decomposition depend on many factors, including temperature, pH, presence or absence of a catalyst (7—10), such as metal ions, oxides, and hydroxides etc. Some common metal ions that actively support homogeneous catalysis of the decomposition include ferrous, ferric, cuprous, cupric, chromate, dichromate, molybdate, tungstate, and vanadate. For combinations, such as iron and... 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

In a recent work we were able to show that an electronic effect was detected between Bi2Mo30i2 and a mixed iron and cobalt molybdate with an enhancement of the electrical conductivity of the cobalt molybdate with the substitution of the cobaltous ions by the ferrous ions (7). However this effect alone cannot explain the synergy effect and we have investigated the influence of both the de ee of subtitution of the cobalt with the iron cations in the cobalt molybdate and the ratio of the two phases (for a given substituted cobalt molybdate) on the catalytic propert cs of the mixture.We have tried to characterize by XPS and EDX-STEM the catalysts before and after the catalytic reaction in order to detect a possible transformation of the solid. The results obtained are presented and discussed in this study. 

Synonym Ammonia Water Amfbnioformaldehyde Ammonium Acetate Ammonium Acid Fluoride Ammonium Amidosulfonate Ammonium Amidosulphate Ammonium Benzoate Ammonium Bicarbonate Ammonium Bichromate Ammonium Bifluoride Ammonium Carbonate Ammonium Chloride Ammonium Citrate Ammonium Citrate, Dibasic Ammonium Decaborate Octahydrate Ammonium Dichromate Ammonium Disulfate-Nickelate (II) Ammonium Ferric Citrate Ammonium Ferric Oxalate Trihydrate Ammonium Ferrous Sulfate Ammonium Fluoride Ammonium Fluosilicate Ammonium Formate Ammonium Gluconate Ammonium Hydrogen Carbonate Ammonium Hydrogen Fluoride Ammonium Hydrogen Sulfide Solution Ammonium Hydroxide Ammonium Hypo Ammonium Hyposulfite Ammonium Iodide Ammonium Iron Sulfate Ammonium Lactate Ammonium Lactate Syrup Ammonium Lauryl Sulfate Ammonium Molybdate Ammonium Muriate Ammonium Nickel Sulfate Ammonium Nitrate Ammonium Nitrate-Urea Solution Ammonium Oleate... 

When the powdered coal is mixed intimately with a catalyst such as 1% (of the dry coal) of ferrous sulfate or 0.2% of ammonium molybdate, the oil yield is increased, and its asphaltene content is reduced. 

The usual chemical employed is sodium molybdate (dihydrate), which acts as an anodic inhibitor and forms, in the presence of some oxygen, a passivating film composed of a ferrous-ferric-Mo-oxides complex. 

Mg as magnesium oxide Fe as Ferrous fumarate Zn as zinc oxide Ti as titanium dioxide Cu as cupric oxide Mo as sodium molybdate I as potassium iodide V as sodium metavanadate Sn as tin(II) chloride... 

Occluded hydrogen is more reactive chemically than the normal gas. Hydrogenated palladium precipitates mercury and mercurous chloride from an aqueous solution of the dichloride, without any evolution of hydrogen. It reduces ferric salts to ferrous potassium ferricyanide to ferrocyanide chlorine water to hydrochloric add iodine water to hydriodic acid 2 chromates to chromic salts ceric to cerous salts whilst cupric, stannic, arsenic, manganic, vanadic, and molybdic compounds are also partially reduced.3... 

Ferric salts are reduced to ferrous,6 and ammonium molybdate likewise suffers reduction.7... 

Blank Mix 10.0 mL of water, 10.0 mL of Acid Molybdate Solution, and 5.0 mL of Ferrous Sulfate Solution. 

Procedure Transfer 10.0 mL each of the Standard Preparation and of the Test Preparation into separate 50-mL Erlenmeyer flasks, add 10.0 mL of Acid Molybdate Solution and 5.0 mL of Ferrous Sulfate Solution to each flask, and mix. Determine the absorbance of each preparation solution and the Blank in a 1-cm cell at 700 nm using a suitable spectrophotometer. The absorbance of the solution from the Test Preparation is not greater than that of the Standard Preparation. Free Riboflavin and Riboflavin Diphosphate (Note Conduct this test so that all solutions are protected from actinic light at all stages, preferably by using low-actinic glassware.)... 

Metal hydroxides in general are anion-selective in acid solution and turn to be cation-selective beyond a certain pH, called the point of the iso-selectivity, pHpjS it is pHpjS = 10.3 for ferric oxide and pHpis = 5.8 for ferric-ferrous oxide [72]. Adsorption of multivalent ions may also control the ion selectivity of hydrous metal oxides because of its effect on the fixed charge in the oxides. For instance, hydrous ferric oxide, which is anion-selective in neutral sodium chloride solution, turns to be cation-selective by the adsorption of such ions as divalent sulfate ions, divalent molybdate ions, and trivalent phosphate ions [70,73]. It is worth emphasizing that such an ion-selectivity change due to the adsorption of multivalent ions frequently plays a decisive role in the corrosion of metals. 

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