Molybdenum Compounds oxide

Both oae-step and two-step oxidation processes are known. A number of catalyst systems are known most use a molybdenum compound as the main component. The acryhc acid is esterified with alcohol to the desired acryhc ester ia a separate process (63—66). 

Molybdenum Oxide. Molybdenum compounds incorporated into flexible PVC not only increase flame resistance, but also decrease smoke evolution. In Table 10 the effect of molybdenum oxide on the oxygen index of a flexible PVC containing 50 parts of a plasticizer is compared with antimony oxide. Antimony oxide is the superior synergist for flame retardancy but has Httle or no effect on smoke evolution. However, combinations of molybdenum oxide and antimony oxide may be used to reduce the total inorganic flame-retardant additive package, and obtain improved flame resistance and reduced smoke. 

Benzene-Based Catalyst Technology. The catalyst used for the conversion of ben2ene to maleic anhydride consists of supported vanadium oxide [11099-11-9]. The support is an inert oxide such as kieselguhr, alumina [1344-28-17, or sUica, and is of low surface area (142). Supports with higher surface area adversely affect conversion of benzene to maleic anhydride. The conversion of benzene to maleic anhydride is a less complex oxidation than the conversion of butane, so higher catalyst selectivities are obtained. The vanadium oxide on the surface of the support is often modified with molybdenum oxides. There is approximately 70% vanadium oxide and 30% molybdenum oxide [11098-99-0] in the active phase for these fixed-bed catalysts (143). The molybdenum oxide is thought to form either a soUd solution or compound oxide with the vanadium oxide and result in a more active catalyst (142). 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

Flame and Smoke Retardants. Molybdenum compounds are used extensively as flame retardants (qv) (93,94) in the formulation of halogenated polymers such as PVC, polyolefins, and other plastics elastomers and fabrics. An incentive for the use of molybdenum oxide and other molybdenum smoke and flame retardants is the elimination of the use of arsenic trioxide. Although hydrated inorganics are often used as flame retardants, and thought to work by releasing water of crystallization, anhydrous molybdenum oxides are effective. Presumably the molybdenum oxides rapidly form... 

Molybdenum compounds Hydrodesulphurization and hydrotreating of petroleum Oxidation of methanol to formaldehdye Epoxidation of olefins Decomposition of alkali metal nitrides Irritation of eyes and respiratory tract Pneumoconiosis... 

Flame resistance A1203, antimony oxides, boron compounds, halogen compounds, phosphate esters, metal hydrates, magnesium compounds, tin compounds, molybdenum compounds, silicones Al, B, Br, Cl, Mo, P, Sb, Si, Sn, Zn... 

The serendipitous discovery of this compound has proven to be extremely important to our visions of possibilities for new metal-metal bonded structures in reduced oxide phases. In retrospect it is amazing that oxide phases containing molybdenum in oxidation states less than 4+ were essentially unknown and certainly structurally uncharacterized. The existence of the previously mentioned series M2 Mo30q and LiM Mo303 should have been a tip-off to an extensive chemistry for metal-metal bonded molybdenum oxide systems. Indeed, subsequent work has revealed a plethora of new compounds all of which (where structure has been determined) feature strong metal-metal bonding in either discrete cluster units or extended chain arrays. 

An extensive literature deals with catalysis by molybdenum compounds (6-15), many of which are isoelectronic with the rhenium analogs of similar but not identical composition. Molybdenum chemistry will not be covered here except by way of comparison. The major oxidation... 

Oxidation catalysis, molybdenum compounds in, 7 7 38 Oxidation chemistry daytime, 77 791-792 in fiber optic fabrication, 77 138-139 nightime, 77 792-793 Oxidation ditch process, in biological waste treatment, 25 905... 

Other procedures for a oxidation of ketones are based on prior generation of the enolate. The most useful oxidant in these procedures is a molybdenum compound, MoOs-pyridine-HMPA, which is prepared by dissolving M0O3 in hydrogen peroxide, followed by addition of HMPA. This reagent oxidizes the enolates of aldehydes, ketones, esters, and lactones to the corresponding a-hydroxy compound.189 190 191... 

Molybdenum(VI) oxide is used in catalyst compositions to carry out desulfurization of petroleum feedstocks and to remove nitrogen-containing compounds from petroleum fractions. Other uses of this oxide include preparation of various molybdate salts and as reagents for chemical analyses. 

Molybdenum(VI) oxide is obtained by igniting molybdenum or its compounds in air ... 

A sulfuric acid solution of the oxide (25-75% solution) can be reduced with tin, copper, zinc, and other reducing agents forming a blue solution of molybdenum blue which are hydrous oxides of non-stoichiometric compositions (see Molybdenum Blue). Reduction with atomic hydrogen under carefully controlled conditions yields colloidal dispersion of compounds that have probable compositions Mo204(OH)2 and Mo40io(OH)2. Reduction with lithium aluminum hydride yields a red compound of probable composition MosOtIOEOs. Molybdenum(Vl) oxide suspension in water also can be reduced to molybdenum blue by hydriodic acid, hydrazine, sulfur dioxide, and other reductants. 

SCHEME 149. Molybdenum-catalyzed oxidation of nitrogen-containing compounds using tert-amyl hydroperoxide... 

The experimental data indicate that molybdenum compounds, including oxides, sulfides, halides, acids, salts, heteropolymolybdic acids, salts of heteropolymolybdic acids, esters of heteropolymolybdic acids, and molybdenum coordination compounds are catalysts for the epoxida-tion reaction. However, certain compounds such as sodium silicomolyb-date, esters of heteropolymolybdic acids, and the coordination compounds (molybdenum hexacarbonyl and molybdenum oxyacetylacetonate) were more effective catalysts. 

Mom+ and Mow+ are written to indicate forms of molybdenum present during the reaction without specifying an exact oxidation level of structure. The number of molybdenum compounds of various valences (Table I) which catalyze this reaction suggest that the initial molybdenum compound may be converted to the same active forms (Step 1). These active forms then complex with the hydroperoxide rapidly (Step 2). 

Fertilizers - [AMMONIA] (Vol2) -in bioremediation piOREMEDIATION] (Supplement) -blended [POTASSIUM COMPOUNDS] (Vol 19) -boron in [BORON COMPOUNDS - BORON OXIDES, BORIC ACID AND BORATES] (Vol 4) -cyanamidein [CYANAMIDES] (Vol 7) -lecithin in [LECITHIN] (Vol 15) -molybdenum compounds m [MOLYBDENUM AND COMPOUNDS] (Vol 16) -nitric acid m mfg [NITRIC ACID] (Vol 17) -potassium hydroxide mmfg of [POTASSIUM COMPOUNDS] (Vol 19) -radioactive tracers for [RADIOACTIVE TRACERS] (Vol 20) -role of H2 m production of [HYDROGEN] (Vol 13) -specialty liquid [POTASSIUM COMPOUNDS] (Vol 19) -tanks for [TANKS AND PRESSURE VESSELS] (Vol 23) -use of diatomite m [DIATOMITE] (Vol 8) -use of sulfur for [SULFUR] (Vol 23)... 

Mercury(II) chloride, 175, 182 Mercury(II) trifluoroacetate, 175 Molybdenum Compounds Molybdenum carbonyl, 194 Molybdenum(VI) oxide, 279 Oxodiperoxymolybdenum(pyridine)-(hexamethylphosphoric triamide),... 

Sodium borohydride-Molybdenum(VI) oxide, 279 Nickel Compounds Bis( 1,5-cyclooctadiene)nickel(0), 35, 199... 

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