US3008897A

US3008897A - Hydrocarbon demetallization process

Info

Publication number: US3008897A
Application number: US832160A
Authority: US
Inventors: Jr Emmett H Burk; Byron W Turnquest
Original assignee: Sinclair Refining Co
Current assignee: Sinclair Refining Co
Priority date: 1959-08-07
Filing date: 1959-08-07
Publication date: 1961-11-14
Anticipated expiration: 1978-11-14

Description

United States Patent 3,008,897 HYDROCARBON DEMETALLIZATION PROCESS Emmett H. Burk, Jr., Hazel Crest, and Byron W. Turnquest, Chicago, Ill., assignors to Sinclair Refining Company, New York, N.Y., a corporation of Maine No Drawing. Filed Aug. 7, 1959, Ser. No. 832,160 11 Claims. (Cl. 208-251) This invention relates to a process for effecting demetallization of petroleum hydrocarbons. In a particular respect the present invention concerns a process for metallizing reduced crude oil fractions boiling predominantly above about 650 F., preferably primarily above about 850 F., to give a product highly susceptible to deoiling for preparing stocks of good catalytic cracking characteristics.

The presence of metals and metal compounds, such as those of copper, vanadium, nickel and iron, in petroleum stocks is undesirable since they impart corrosive properties to the stocks, contribute to ash depositon, and are responsible for catalyst deterioration when fractions containing the metals are used as charging stocks in catalytic cracking operations. Thus, in catalytic cracking operations as heretofore carried out, it has, in most cases, been necessary to use gas oil or other relatively metalsfree distillates as all or the major portion of the charging stock.- One important factor which has prevented the use of reduced crude oil fractions for this purpose is that, with such feedstocks, the catalyst rapidly deteriorates and undesirably large amounts of coke and gas are obtained during cracking in stocks boiling primarily above 850 F. Normally nickel is present as NiO in at least about 40 parts per million and vanadium is present in amounts of at least about 150 parts as V 0 per million.

Previous work exemplified by US. Patents Nos. 2,729,- 593 and 2,744,853 has shown that hydrocarbon oils, containing metal contaminants may be demetallized by the use of iodine, aqueous hydrogen iodide, and iodine in the presence of hydrogen. Treatment of the oil with iodine in the absence of hydrogen gives a low yield of demetallized oil, when hydrogen is included the demetalliza-tion is wasteful of hydrogen as a result of the high hydrogen consumption by the oil. The latter is caused by the high partial pressures of hydrogen required to achieve good demetallization. If the hydrogen partial pressure is lowered, demetallization is poorer and as the partial pressure approaches zero, the yield of product is greatly reduced due to the formation of insoluble sludge.

An important application of the present invention relates to removing metal contaminants from residuums resulting from the distillation of a crude petroleum oil. The residuums of the distillation operation are ordinarily employed as a bunker fuel or the like. The residuums, however, generally contain appreciable quantities of metals such as nickel and vanadium as well as other metals or metal compounds. Removal of these contaminants will make the residual petroleum stocks more suitable as fuels lending them less corrosive or as catalytic cracking charge stocks.

In the present invention we have found that the contact of petroleum fractions which are liquid at treating conditions, particularly residuals such as asphalts, tars, vacuum distillation bot-toms, etc., boiling predominantly above about 650 F., preferably predominantly above about 850 E, which fraction-s contain metal contaminants, with a catalytic amount of hydrogen iodide together with a hydroaromatic compound, provides a highly effective method for removing metal contaminants from the petroleum stock. The feedstocks normally contain upwards of about 40 p.p.m. of NiO and more than about 100 or 150 ppm. of V 0 and are frequently of high nitrogen or sulfur content. In our process there .is at least about 40% demetallization and preferably at least about to about or more demetallization. Further, by employing the process of this invention, demetallization is achieved with low hydrogen consumption while avoiding most, if not all, insoluble organic sludge formation. :We sometimes make a small amount of inorganic precipitate which is easily filtered out of the products.

Our process is conducted under suitable temperature and pressure conditions so that there is not a substantial amount of cracking, i.e. less than about 15 weight percent cracking, preferably less than about 5%, of the petroleum feedstock. The treating temperature. will usually be in the range of about 500 to 725 F., with about 575 to 725 F. being most .suitable. The reaction pressure is usually at least about p.s.i.g., more often at least about 300 p.s.i.g., and no reason has been seen for going above about 3000 p.sii.-g., and preferably the pressure will not be above about 1500 to 2000 p.s.ig. When treating residuals the pressure may be essentially only the vapor pressure of the liquid hydroaromatic compound. Although we prefer not to introduce free hydrogen into the system which reduces the hydrogen consumption efficiency this can be done and the pressure is increased accordingly. 'For instance, the hydrogen partial pressure would be at least about v100 p.s.i.g., for instance about 200 to 500 p.s.i.g., and could be as much as about 2000 to 3000 p.s.i.g. or more. The length of time of our treatment may vary widely so long as conversion of the petroleum feed is limited as noted before. The treatment may take from about 0.1 to 5 hours or more and seems of little benefit after 10 hours. The preferred time is about 0.5 to 3 hours and, of course, lower temperatures may give rise to longer contact times to obtain a given result. 7

The hydro-aromatic compound can be contacted with the hydrocarbon oil to be treated in any suitable manner. The agent may be added to the oil prior or subsequent to the addition of the catalyst to the oil. The amount of hydroaromatic compound employed .is generally at least about 20% of the residual feed and usually is in a range of from about 50 to 200 percent by weight of the oil treated. The hydroaromatic material can be added as a relatively pure chemical such as tetralin or decalin or in admixture with other materials, particularly hydrocarbons. Also, the hydroaromatic material may be a hydrogenated catalytic cycle oil, a hydrogenated lubricating oil extract or other hydrogenated aromatics inclding naphthenes obtained by hydrogenation of aromatics or by other means. The hydroaromatic material is a liquid at the conditions of our process and acts as a hydrogen donor. When added in admixture with other hydrocarbons the hydroaromatic is usually at least about 40 'or 50%, preferably at least about 75%, of the mixture. When treating residuals the hydroaromatic material is preferably low boiling so that it may be separated overhead by distillation from the product. Since substantial cracking is avoided in our demetallization operation the lighter donor is readily recovered since it will not 'be unduly contaminated with light gases. If on the other hand, the entire product is going to a catalytic cracking unit the boiling range of the donor is of less significance.

The catalyst in our process is essentially hydrogen iodide which can be added as such to the reaction zone or we can add iodine or another hydrogen iodide-producing material. 'In any event the hydrogen iodide is apparently in equilibrium with elemental iodine in the reaction zone although the catalyst may be predominantly hydrogen iodide. The catalyst can be contacted with the petroleum feedstock in any convenient manner and the catalyst is essentially in anhydrous form although it may be used in solution with alcohol or other solvents. The amount of catalyst used can depend upon the reaction conditions and the amount of demetallization required but (is generally from about 0.1 to 20% of the oil to be demetallized, preferably about 1 to 10%.

Our treatment may be carried out continuously, as by passing the oil and the reagents into a reactor and heating under the desired conditions of temperature, pressure, and time. The resulting mixture of oil and metal compounds together with any excess reagents is passed to suitable separators to separate the oil from the tarry metal salt precipitate and obtain the donor. The recovered agents may be recycled to the continuous process. Also, a batchwise type operation may be carried out by mixing the oil with the catalyst and the donor under the treating conditions. The recovered agents may again be used until exhausted.

Demetallization by this invention is obtained without the expensive loss of large amounts of hydrogen which normally occurs in processes which employ hydrogen iodide, iodine or their mixtures. Further, the burdensome, fouling, insoluble sludge normally precipitated in these commercial processes is either substantially reduced or in some cases eliminated by the process of this invention.

The following examples are not necessarily to be considered limiting. In the examples the hydrogen pressures were measured at room temperature.

EXAMPLE I Initial B.P F 950 Specific gravity 1.002 Nickel oxide p.p.m 90 Vanadium oxide p.p.m 245 Conradson carb n 20.5

The pertinent results obtained by shown in Table I.

this example are Table I A B C D E Total pressure, p.s.i.g 150 500 1, 000 2,000 160 H partial pres., p.s.i.g 500 1, 000 2,000 0 Tetralin/asphalt, wt. ratio O/l 0/1 0/1 0/1 1/1 Wt. percent yield of asphalt (sludge free) 90 98. 8 98. 8 97. 8 99. 2 Sp. gr. of product .989 1.003 .996 986 1. 003 Hydrogen cons, s.c.f./bbl 252 465 490 66 Product:

Nickel oxide, p.p.rn 42 90 94 74 76 Vanadium oxide, p.p.m 128 240 190 96 110 Total demetaL, percent 50 0 16 50 45 Conradson carbon: 14. 71 12.2 10. 5 13.3 Sulfur, percent by wt .93 97 .86 1. 1 Nitrogen, percent by wt .51 43 .39 62 Run A had comparatively satisfactory demetallization of about 50 percent but most of the metal contaminant became tied up in the insoluble organic sludge. Separation thus became a problem, and the run was further unsatisfactory as heavy sludging occurred resulting in low asphalt yield. In runs B, C and D, which were similar to run A in lacking a donor but which unlike A had hydrogen present, show that demetallization increases with hydrogen pressure but such an increase results in a large increase in hydrogen consumption. In the process of this invention conducted in the absence of hydrogen, shown in run B, there was almost no organic sludge formation while the metal contaminants were easily removable by filtration. Also by the process of this invention, a product of low conradson carbon was obtained while maintaining comparatively satisfactory demetallization characteristics and a very low rate of hydrogen consumption, i.e. over 7 times less hydrogen than that consumed in comparative run D.

EXAMPLE II Table II Run F G Total Pressure, p.s.l.g t H Partial Pressure, p.s.l.g Tetralin/Asphaltic Oil, wt. ratio 0/1 1/1 Wt. percent Yield of (sludge free) Asphaltle oil 94. 5 97. 5 Specific Gravity of product .959 .980 Hydrogen Cons, s.c.f./bbl 464 226 Product:

Nickel Oxide, p.p.rn 5. 5 17.8 Vanadium Oxide, p.p.m 10.2 13.0 Total Demetallization Conradson Carbon content 8. 10 12. 8 Sulfur, wt. percent 91 87 Nitrogen, wt. percent 27 46 While demetallization in runs F and G are both comparatively satisfactory, it was shown that run G containing tetralin had a marked reduction, in organic sludging and further only about one-half as much hydrogen was consumed when tetralin was utilized according to the process of this invention.

Aside from high metals contents the conradson carbon of residual mitigates their use as feedstock to catalytic cracking units making high octane gasoline, e.g. a fluid catalyst unit employing a silica-alumina catalyst. We have found that the asphaltic product from our demetallization operation can be deoiled or extracted to obtain further reductions in metal content and a product of low conradson carbon and thus of relatively low cokeforming tendency in catalytic cracking. Thus this heavy feedstock could be so cracked with advantage particularly when blended with straight run gas oils. Moreover, the feedstock would be more suitable as a hydrocracking feedstock.

In the deoiling, a hydrocarbon solvent such as a lower aliphatic hydrocarbon is frequently employed to extract the desired product. Suitable solvents are n-pentane, n-butane and n-propane, which would normally be employed in an oil to solvent ratio of from about 1 to 200:1 to 10, the preferred oil to solvent ratio being from about 1 to :1 to 20. The deoiling normally takes place at any suitable pressure where the solvent is a liquid, e.g. atmospheric pressure or somewhat elevated pressures, while the temperature is most advantageously an ambient temperature. The deoiled product could be used as a feedstock in a catalytic cracking process such as the fixed bed, moving bed or fluidized bed cracking catalytic cracking processes, but preferably in the latter. In each of these types of operation, any of the various well known cracking catalysts may be employed. Generally, such catalysts are the metal oxide types, usually silica based, and preferably include silica-alumina, silica-magnesia, or silica gel promoted with metal oxides which are adsorbed thereon. Typical cracking conditions are at temperatures in the range of about 750 to 1050 F. and pressures ranging from atmospheric pressure to about 2000 p.s.i.g. pressure. The catalytic agent employed is regenerated intermittently or continuously in order to restore or maintain the activity of the catalyst.

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Table III Run H I J K Temp., F 700 600 700 600 P.s.i.g. (H 1,000 1,000 2,000 P.s.i.g. Total 1, 000 200 1, 250 2,000 Contact Time (Hrs.) 1 22 1 26 H Donor/asphalt, wt. rat None 1/1 1/1 Catalyst, percent I on Feed 17. 2 12 0 14.0 8.17 14. 20 9. 66 7. 54 11.08 7. 93 86. 25 86. 62 86. 60 86. 41 Percent H 11.59 11.25 11.48 11.99 Percent N. 0.25 0. 47 0. 35 0.19 0. 53 0. 88 0. 72 0. 57 Percent I- 0.80 0.49 0. 56 0. 54 N10, p p m 58 30 4. 56 4 V 05, 73 30 11. 6 12. 8 Percent Total D etall atl 61 82 95 95 H/O Atomic Ratio 1.63 1. 55 1. 58 1. 66 Percent Benzene Insol 8.05 2. 56 3.07 4. 28 Recovery, Wt. percent 84. 0 85. 8 97. 6 99. 1 n-O Extract:

Percent Yield 93. 4 88. 5 91. 9 95. 7 N10, p.p.m 8. 2 6.3 1.48 1.46 V 05, p.p.m 56 12.2 3. 34 7. 4

Thus the product of our invention can be readily deoiled to lower metals content for a given hydrogen consumption and the product of run I would have a conradson carbon of less than 1 which is in sharp contrast to the results obtained when deoiling residuals not treated in accordance with our invention.

We claim:

1. A process for demetallizing a metals-containing petroleum fraction which comprises contacting said fraction without substantial cracking at a temperature of from about 500 to 725 F. with a catalytic amount of hydrogen iodide and a hydroaromatic material in an amount of at least about 20% based on said petroleum fraction and separating a demetallized product.

2. The process of claim 1 wherein the petroleum fraction boils predominantly above about 850 F.

3. The process of claim 2 wherein the demetallization is conducted in the presence of at least about 100 p.s.i.g partial pressure of free hydrogen.

4. The process of claim 2 where the hydroarornatic material is tetralin.

5. The process of claim 2 where the temperature is from about 575 F. to 725 F.

6. A process for demetallizing a metals-containing petroleum residual boiling predominantly above about 850 R, which comprises contacting said residual without substantial cracking at a temperature of from about 575 F. to 725 F. and at a pressure of from about 300 to 1500 p.s.i.g. with about 1 to 10% of hydrogen iodide and about 20 to 200% of a hydroaromatic material.

7. A process for demetallizing a metals-containing petroleum residual boiling predominantly above about 850 R, which comprises contacting said residual without substantial cracking at a temperature of from about 575 F. to 725 F. and at a pressure of from about 300 to 1500 p.s.i.g. with about 1 to 10% of hydrogen iodide and about 20 to 200% of a hydroaromatic material, and deoiling the resulting product to obtain a further reduction in metals in the metals-containing petroleum fraction.

8. A process for demetallizing a metals-containing petroleum fraction which comprises contacting said fraction without substantial cracking at a temperature of from about 500 to 725 F. with a catalytic amount of hydrogen iodide and a hydroaromatic material in an amount of at least about 20% based on said petroleum fraction, separating a demetallized product, and deoiling the resulting product to obtain a further reduction in metals in the metals-containing petroleum fraction.

9. A process for demetallizing a metals-containing petroleum fraction boiling predominantly above about 850 P. which comprises contacting said fraction without substantial cracking in the presence of at least about p.s.i.g partial pressure of free hydrogen at a temperature of from about 500 to 725 F. with a catalytic amount of hydrogen iodide and a hydroaromatic material in an amount of at least about 20% based on said petroleum fraction, and separating a demetallized product.

10. The process of claim 6 wherein the demetallization is conducted in the presence of at least about 100 p.s.i.g. partial pressure of free hydrogen.

11. The process of claim 7 wherein the demetallization is conducted in the presence of at least about 100 p.s.i.g. partial pressure of free hydrogen.

References Cited in the file of this patent UNITED STATES PATENTS 2,141,615 Pott Dec. 27, 1938 2,426,929 Greensfelder Sept. 2, 1947 2,606,141 Meyer Aug. 5, 1952 2,729,593 Garwood Jan. 3, 1956 2,744,853 Kavanagh May 8, 1956

Claims

1. A PROCESS FOR DEMETALLIZING A METALS-CONTAINING PETROLEUM FRACTION WHICH COMPRISES CONTACTING SAID FRACTION WITHOUT SUBSTANTIAL CRACKING AT A TEMPERATURE OF FROM ABOUT 500 TO 725*F. WITH A CATALYTIC AMOUNT OF HYDROGEN IODIDE AND A HYDROAROMATIC MATERIAL IN AN AMOUNT OF AT LEAST ABOUT 20% BASED ON SAID PETROLEUM FRACTION AND SEPARATING A DEMETALLIZED PRODUCT.