Mineral oils: processes and products – Refining – Metal contaminant removal
Reexamination Certificate
1999-08-05
2001-12-04
Yildirim, Bekir L. (Department: 1764)
Mineral oils: processes and products
Refining
Metal contaminant removal
C208S226000, C208S287000
Reexamination Certificate
active
06325921
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a method for catalytic removal of metal compounds from heavy oils.
Description of the Related Art
A large proportion of known oil reserves in the world are in the form of so-called heavy oils; as an example, it can be noted that for Venezuela alone, the quantity of recoverable heavy oil is estimated at 270 billion barrels.
Heavy oils as a rule contain metal compounds, often in large quantities, and especially vanadium and nickel. Because of these metal compounds, the use of heavy oils is generally restricted to their use as fuel.
There are a great many commercial methods available for reducing or concentrating metals in heavy oils. These methods can be subdivided into thermal methods, such as visbreaking, coking, and delayed coking, along with mild hydrotreatment or conversion to combustion gases, on the one hand, and catalytic processes such as hydrocracking and catalytic cracking, on the other.
In thermal methods, temperatures of more than 500° C. are needed; furthermore, these methods lead to the production of great amounts of coke. In the thermal methods, the metals become concentrated in the coke being formed. In the catalytic methods, the need for hydrogen under high pressure is very great, and the costs for the plants are therefore equally high. Since the metals are precipitated predominantly onto the catalysts, the consumption of catalysts is also very high.
Especially for removing metal compounds from heavy oils, methods using supercritical water are employed commercially; they are based on the fact that in the vicinity of the critical point of water (374.1° C.;218.3 atm), the properties of the water change very quickly as a function of temperature and pressure. This “supercritical water” has completely different dissolution properties from normal water; an especially notable fact is that the solution performance for nonpolar organic compounds such as heavy hydrocarbons rises sharply, because these compounds are soluble in water under supercritical conditions. This is of major significance for chemical reactions, since in the reactions of heavy oils in water, only one phase exists. However, in the treatment of heavy oils with water, there is one limiting factor, because heavy oils contain compounds that form coke very rapidly. The upper temperature limit must therefore as a rule be below 440° C., to prevent excessive coke formation, which would lead to stopping up of the reactor systems. Methods for removing or concentrating metal compounds from heavy oils in the presence of water near the critical point are described for instance in U.S. Pat. Nos. 3,983,027, 3,453,206, 3,733,259, 3,586,621, 4,446,012, and 4,743,357. In these methods, the metals from the unprocessed heavy oil are typically present, after the treatment, in unconverted form usually in the heaviest portion of the outflowing oil product. This can be ascertained from the refraction properties of the organometallic compounds.
In U.S. Pat. No. 4,446,012, for instance, a noncatalytic method is described, in which Boscan heavy oil from Venezuela at a temperature of 410 ° C. and a pressure of 140 bar was used as the supply; it had a density (API) of 10.3 and a vanadium and nickel content of 1500 and 100 ppm, respectively. After the treatment with water at supercritical conditions, the outflowing oil was separated into two fractions, one with a boiling point below 343° C. and soluble in pentane, which made up 64.6 weight % of the original fraction and represented the light fraction after conversion, and a second fraction with a boiling point of over 343° C., which was insoluble in pentane, represented 22.2 weight % of the original fraction, and was called the heavy fraction. The untreated heavy starting oil originally contained approximately 15 weight % that met the definition of a light fraction. After the treatment, vanadium and nickel contents of 7.8 ppm and 1.2 ppm, respectively, were found in the light fraction, while in the heavy fraction a concentration of vanadium and nickel to 5900 ppm and 600 ppm, respectively, had taken place.
It is therefore possible and known to concentrate metal compounds in the heavy fractions of heavy oil, if the oil is treated with water in the vicinity of the critical point.
One disadvantage of these known methods, however, is that the metals in fact collect predominantly in the heavy fraction, which means that this heavy fraction requires further special, and complicated, treatment before it can be used commercially in any way at all. Such fractions enriched with metals also represent a severe problem from the standpoint of environmental protection.
There is accordingly still a demand for methods for catalytic removal of metal compounds from heavy oils that overcomes the problems of the previously known methods. For attaining this object, a method is proposed which is characterized in that a catalyst with a content of a metal of group IVB and a metal of group IA of the periodic system is used, at temperatures between 300 and 550° C. and at a pressure between 100 and 300 atm.
BRIEF SUMMARY OF THE INVENTION
Completely surprisingly, it has now been demonstrated that heavy metal compounds can be removed from heavy oils with excellent yields and effective reduction of the metal contents and with avoidance of the passage of the metal compounds into the heavy fraction of the outflowing oil, if a specific type of catalyst is employed.
Catalysts from compounds of group IVB and IA of the periodic system are known from European Patent Disclosure EP 0 402 405, but in that case they are intended for use in gasification processes for organic substances. Zirconium oxide, which is stable at the relatively high temperatures, is preferably used as the compound from group IVB. The compound from group IA that is preferably used is potassium carbonate, but it can also be replaced with other potassium salts. Other metal compounds of group IA and IVB can also be used; the ratio of compounds of group IA to those of group IVB should be in the range from approximately 0.01:1 to 0.5:1.
The methods of the invention are preferably performed with a fixed bed catalyst in the reactor, specifically in such a way that zirconium oxide in the form of granulate or tablets, impregnated with potassium carbonate, is employed.
The invention offers the advantage that an effective metal removal is accomplished, and no enrichment of the metal compounds in the heavy fraction of the outflowing oil takes place. The separate treatment and disposal of this heavy phase is therefore dispensed with.
REFERENCES:
patent: 3453206 (1969-07-01), Gatsis
patent: 3586621 (1971-06-01), Pitchford et al.
patent: 3733259 (1973-05-01), Wilson et al.
patent: 3983027 (1976-09-01), McCollum et al.
patent: 4381993 (1983-05-01), Nevitt
patent: 4446012 (1984-05-01), Murthy et al.
patent: 4743357 (1988-05-01), Patel et al.
patent: 5284577 (1994-02-01), Shih et al.
patent: 0 402 405 B1 (1993-12-01), None
Pillsbury & Winthrop LLP
Yildirim Bekir L.
LandOfFree
Method for catalytic removal of metal compounds from heavy oils does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for catalytic removal of metal compounds from heavy oils, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for catalytic removal of metal compounds from heavy oils will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2595174