Vanadium organo compounds

Titanium, vanadium or chromium oxides activated with chlorine-free organo-aluminum compounds, triethyl- or triisobutyl aluminum, have also been used as catalysts [285],... 

In hydrotreating processes heteroatoms, such as sulphur, nitrogen, oxygen and metals, are catalytically removed from heavy oil residua. These metals, mainly vanadium and nickel, remain in the reactor as solid deposits accumulating on the catalyst surface after decomposition of the organo-metallic compounds. 

Also, coordination compounds and metal carbonyls are able to undergo a PET, resulting in initiating radicals [63]. Recently investigated examples are iron chloride based ammonium salts [149], vanadium(V) organo-metallic complexes [150], and metal sulfoxide complexes [151]. However, the polymerization efficiency of some systems is only low due to redox reactions between the central metal ion and the growing polymer radical, and the low quantum yields of PET. 

The catalysts are usually prepared in hydrocarbon solvents, essentially in the absence of air or moisture and are mixtures of ill-defined composition. In many instances dark-coloured precipitates are formed of variable stoichiometry containing complexes of the organo-metal compound with the transition metal in a lower valence state. Natta [5] showed that pure lower valence transition metal compounds, such as titanium or vanadium trichloride, when treated with organo-metal compounds were effective catalysts, and were particularly suitable for the preparation of crystalline high melting point polyolefins. The close identity of these two classes of catalyst has led to their description as... 

A joint research program (Hydrocarbon Research, Inc.—Cities Service Research and Development Co.) has been underway for more than three years at the HRI laboratories to develop a demetallization procedure which would reduce the nickel and vanadium contents of fuel oils and thus produce an oil for further processing by H-Oil at low catalyst addition rates. These research eflForts have resulted in the development of solid adsorbent materials which are low in cost and which eflFectively remove the bulk of the organo-metallic compounds present in such oils. These solids are used in an H-Oil reactor with the conventional ebullated-... 

The alkyl phosphoric acids were first recognized as excellent actinide extractants because dibutyl phosphoric acid existed as an impurity in TBP (8). They extract well from unsalted solutions and from systems such as sulfate in which TBP is ineffective. Organo-phosphorus acids are thus suitable for uranium hydr metallurgical applications where ore is leached with sulfuric acid. The Dapex process is an example in which bis(2-ethylhexyl) phosphoric acid (HDEHP) is used alone or in synergistic combination with neutral organophosphorus compounds for uranium and vanadium recovery (9,10). 

Organo-metallic compounds. Crude oil for instance usually contains vanadium and nickel that may be present in combination with complex organic structures. 

Organo-metallic compounds contained in the feed will be decomposed and the metals will be retained on the catalyst, thus decreasing its activity. Since metals are normally not removable by oxidative regeneration, once metals have poisoned a catalyst, its activity cannot be restored. Therefore, metals content of the feedstock is a critical variable that must be carefully controlled. The particular metals which usually exist in vacuum gas oil type feeds are naturally occurring nickel, vanadium and arsenic as well as some metals which are introduced by upstream processing or contamination such as lead, sodium, silicon and phosphorous. Iron naphthenates are soluble in oil and will be a poison to the catalyst. Iron sulfide as corrosion product is normally not considered a poison to the catalyst and is usually omitted when referring to total metals. 

In contrast to the above discussion, vanadium oxide is also known to play a crucial role in the deactivation of ultra stable Y (USY) zeolite in fluid cata-lylic cracking (FCC) processes. Vanadium is known to enhance the removal of sodium ions from zeolite Y, thereby acting as a promoter/catalyst. These Na+ ions released are known to attack and destroy the Si-OSi frame in the zeolite there by deactivating it. The source of vanadium in FCC processes comes from crude oil (feed) which contain V-porphyrin and organo-vanadium compounds. The released vanadium migrates to the surface of zeolite. In this process, vanadium is known to fluctuate between oxidation states there by making it a redox... 

Vanadium - The oxovanadium(V)-induced oxidative coupling of organo-lithium and -magnesium compounds has been investigated by V NMR spectroscopy. NMR spectroscopy has been used to follow the reaction of [V02(acac)] with... 

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