Vanadium catalyst residues

Method 1.3 Determination of Vanadium Catalyst Residues in Ethylene-propylene Rubber. Ashing - Spectrophotometric Procedure... 

This spectrophotometric procedure determines vanadium catalyst residues in amounts down to 2 ppm in ethylene-propylene rubbers. 

METHOD 66 - DETERMINATION OF ALUMINIUM AND VANADIUM CATALYST RESIDUES IN POLYALKENES AND POLYALKENE COPOLYMERS. ASHING - SPECTROPHOTOMETRIC PROCEDURE. ... 

This spectrophotometric procedure determines aluminium and vanadium catalyst residues in polyolefins and their copolymers in amounts down to 20 ppm (aluminium) and 1 ppm (vanadium). 

Determination of aluminium and vanadium catalyst residues in polyalkenes... 

Determination of vanadium catalyst residues in ethylene-propylene rubber. 

In the United States, the largest concentration of atmospheric vanadium occurs over Eastern seaboard cities where residual fuels of high vanadium content from Venezuela are burned ia utility boilers. Coal ash ia the atmosphere also coataias vanadium (36). Ambient air samples from New York and Boston contain as much as 600—1300 ng V/m, whereas air samples from Los Angeles and Honolulu contained 1—12 ng V/m. Adverse pubHc health effects attributable to vanadium ia the ambieat air have aot beea deteroiiaed. lacreased emphasis by iadustry oa controlling all plant emissions may have resulted ia more internal reclamation and recycle of vanadium catalysts. An apparent drop ia consumption of vanadium chemicals ia the United States since 1974 may be attributed, in part, to such reclamation activities. 

Catalyst residues, particularly vanadium and aluminum, have to be removed as soluble salts in a water-washing and decanting operation. Vanadium residues in the finished product are kept to a few ppm. If oil-extended EPDM is the product, a metered flow of oil is added at this point. In addition, antioxidant, typically of the hindered phenol type, is added at this point. 

Vanadium is recovered from several sources vanadium minerals, vanadium-bearing phosphates, boder residues, and spent vanadium catalysts. One major vanadium mineral is patronite, a greenish-black, amorphous sulfide ore used extensively for many years to produce vanadium. This mineral, found in Peru, has depleted gradually. The metal also is recovered commercially from carnotite and roscoelite. 

Vanadium. A residual oil was desulphurized (673 K, 115 atm) with a non-stoicheiometric vanadium sulphide (S/V, 0.8-1.8) formed in situ from VS4 Vanadium sulphide catalysts have been prepared by in situ sulphiding of vanadium complexes, e.g., bis(acetylacetonato)oxovanadium(IV), dissolved in crude petroleum.Vanadium compounds occurring in heavy oils have been activated as desulphurization and demetallization catalysts by treatment with triethylaluminium. Catalysts consisting of vanadium promoted by nickel can be prepared in situ by deposition of the metals from heavy crude oils. Ni-V hds and hdm catalysts on silica or carbon have been claimed. 

The presence of vanadium in petroleum crudes is well documented. Much analytical data " have been compiled because the metal brings about unfavorable effects in poisoning cracking and other catalysts in the standard refinery operations. Furthermore, presence of vanadium in residual fuels at high levels results in damage to furnace components. 

The total amount of vanadium in residual fuel oil is probably greater than in any other product of petroleum refining. About 668 million barrels of fuel oil were consumed in the United States in 1968, and this material is estimated to have contained nearly 19,000 tons of vanadium. At the current price, this amount of vanadium is worth about 100 million. Desulfurization of fuel Oil can reduce the vanadium content about proportionate to the reduction of sulfur.If fuel oil is desulfurized to reduce atmospheric pollution, can a significant amount of vanadium be recovered profitably from the catalysts used in the desulfurizing process or at some other stage in this process ... 

Due to moderate catalyst activities and high content of vanadium in the polymer, special purification steps were required to remove catalyst residues. From Table 1 it is apparent that modem metallocene-based catalysts offer attractive opportunities for olefin copolymerization. 

Vanadium Vanadium from residual fuels is captured in the catalyst. Catalyst activity increases with time also for undesired reactions SO2 conversion, risk of ammonia salt formation and NH3 oxidation increase... 

The suspension process will normally produce in the range of 20-60 X 10 g polymer per gramme of vanadium catalyst (depending on the type of elastomer). The slurry is discharged continuously from the reactor and it is not necessary to remove the catalyst residues because of the small quantities involved. The non-converted monomers are steam separated, recovered, purified and recycled to the reactor. The polymer, which is now in an aqueous suspension, is separated from the water by a shaker screen, and is then dried and baled. 

Acid Leaching. DHect acid leaching for vanadium recovery is used mainly for vanadium—uranium ores and less extensively for processing spent catalyst, fly ash, and boiler residues. Although 20 in spent catalysts dissolves readily in acid solutions, the dissolution of vanadium from ores and... 

Most U.S. production (20 x 10 lbs ia 1996) of primary vanadium compounds has been as by-products or coproducts of uranium and of ferrophosphoms derived from smelting Idaho phosphates. Most of this processiag was from leaching acids, residues, and spent catalysts. The only domestic commercially mined ore, for its sole production of vanadium, is Arkansas brookite. It has contributed significantly to domestic supply siace ca 1969, however, it has not been mined siace 1992 (25). 

Vanadium and nickel are poisons to many catalysts and should be reduced to very low levels. Most of the vanadium and nickel compounds are concentrated in the heavy residues. Solvent extraction processes are used to reduce the concentration of heavy metals in petroleum residues. 

The residual portion of feedstocks contains a large concentration of contaminants. The major contaminants, mostly organic in nature, include nickel, vanadium, nitrogen, and sulfur. Nickel, vanadium, and sodium are deposited quantitatively on the catalyst. This deposition poisons the catalyst permanently, accelerating production of coke and light gases. 

The most important undesired metallic impurities are nickel and vanadium, present in porphyrinic structures that originate from plants and are predominantly found in the heavy residues. In addition, iron may be present due to corrosion in storage tanks. These metals deposit on catalysts and give rise to enhanced carbon deposition (nickel in particular). Vanadium has a deleterious effect on the lattice structure of zeolites used in fluid catalytic cracking. A host of other elements may also be present. Hydrodemetallization is strictly speaking not a catalytic process, because the metallic elements remain in the form of sulfides on the catalyst. Decomposition of the porphyrinic structures is a relatively rapid reaction and as a result it occurs mainly in the front end of the catalyst bed, and at the outside of the catalyst particles. 

DFCr systems appear to have the necessary metals tolerance to process residual oils and the abundant, cheaper, but heavily vanadium-contaminated, Venezuelan and Mexican crudes (1-4). Therefore, the dual function fluid cracking catalyst (DFCC) concept could lead to the generation of important catalysts for U.S. refineries should Middle East politics cause another sudden escalation in crude oil prices and availability. The concept is... 

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