GB1560599A

GB1560599A - Process for demetallizing hydrocarbon oils

Info

Publication number: GB1560599A
Application number: GB28313/77A
Authority: GB
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1976-07-08
Filing date: 1977-07-06
Publication date: 1980-02-06
Also published as: SE421930B; NL7607552A; NL187026C; SE421930C; BE856187A; NO772401L; SE7707885L; FI65079B; DE2730565A1; IT1082115B; AU504664B2; JPH0122319B2; FR2357635A1; DK304177A; FI65079C; FI772119A; CA1094490A; FR2357635B1; DE2730565C2; JPS537704A

Description

(54) PROCESS FOR DEMETALLIZING HYDROCARBON OILS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a company organised under the laws of the The Netherlands, of 30 Carel van Bylandtlaan, The Hague, The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a process for demetallizing hydrocarbon oils by contacting the oils with a catalyst at elevated temperature and pressure and in the presence of hydrogen.

In British patent specification No. 1,438,645 catalysts are described which are promoted with one or more metals having hydrogenation activity and which meet the following requirements: (1) p/d > 3.5-0.02 v, in which p is the specific average pore diameter in nm, d is the specific average particle diameter in mm and v is the percentage of the total pore volume that consists of pores with a diameter larger than 100 nm, 2 the total pore volume is larger than 0.40 ml/g, 3 v is smaller than 50% and 4 the specific surface area is larger than 100 m2/g; for the case that the catalyst has such as p and d that the quotient p/d is not larger than 10-0.15 v, the catalyst meets the following additional requirements: (a) the nitrogen pore volume is larger than 0.60 ml/g, (b) the specific surface area is larger than 150 m2/g, and (c) p is larger than 5 nm.

According to aforementioned British patent specification these catalysts are eminently suitable for use in the hydrodemetallization of metal-containing hydrocarbon oils. As was demonstrated in the examples of said British patent specification, it is of vital importance for the catalysts to be promoted with one or more metals having hydrogenation activity (compare experiment 40 where a non-promoted catalyst was used for demetallizing an oil having a total vanadium and nickel content of 245 ppmw).

Continued investigation concerning the use of catalysts meeting the above-mentioned requirements with regard to porosity and particle size for the hydrodemetallization of hydrocarbon oils has shown that similar catalysts, but not promoted with one or more metals having hydrogenation activity, are nevertheless very suitable for this purpose, provided that the hydrocarbon oils concerned have a total vanadium and nickel content of more than 500 ppmw. Catalysts meeting the above-mentioned requirements with regard to porosity and particle size but not promoted with one or more metals having hydrogenation activity will, for the sake of brevity, in this patent application further be designated: non-promoted catalysts.

The present invention therefore relates to a process for demetallizing hydrocarbon oils with a total vanadium and nickel content of more than 500 ppmw, the oils being contacted at elevated temperature and pressure and in the presence of hydrogen with a non-promoted catalyst. For further information concerning the determination of p and d reference is made to above-mentioned British patent specification.

Very suitable materials to be used as catalysts in the process according to the invention are oxides of the elements of Groups II, III and IV of the Periodic Table of Elements or mixtures of said oxides, such as silica, alumina, magnesia, zirconia, boria, silica-alumina, silica-magnesia and alumina-magnesia.

Another type of material that is very suitable to serve as the catalyst in the process according to the invention is soot, in particular a soot obtained as a by-product in the partial oxidation of hydrocarbons with air, oxygen or mixtures of air and oxygen, either in the presence of in the absence of steam.

As catalysts for the process according to the invention aluminas, silicas and silicaaluminas are preferred. Very suitable catalysts are alumina or silica particles prepared by spray-drying of an alumina or silica gel, followed by shaping of the spray-dried micro particles into larger particles, e.g. by extrusion, and spherical alumina or silica particles obtained by the well-known oil drop method. The latter method comprises formation of an alumina or silica hydrosol, combining the hydrosol with a gelating agent and dispersing the mixture as droplets in an oil which may be kept at an elevated temperature; the droplets remain in the oil until they have solidified to form spherical hydrogel particles, which are subsequently separated, washed, dried and calcined. Very suitable silica-alumina catalysts are cogels of aluminium hydroxide gel on silica hydrogel.

The present catalysts may, inter alia, be shaped by extrusion or pelletizing. In addition to these shaping techniques especially the well-known nodulizing method is a very attractive shaping technique for the present catalysts. According to this method catalyst particles having a diameter of at most 0.1 mm are agglomerated with the aid of a granulation liquid to form particles having a diameter of at least 1.0 mm.

The demetallization activity of non-promoted catalysts according to the present patent applicaton and of promoted catalysts to the present patent application and of promoted catalysts according to British patent specification No. 1,438,675 can be increased by the addition of hydrogen sulphide. Demetallization of heavy hydrocarbon oils with the aid of these catalysts is therefore preferably carried out with addition of hydrogen sulphide. In a further investigation concerning the influence of the addition of hydrogen sulphide when using the present non-promoted catalysts and promoted catalysts according to British patent specification No. 1,438,645 for demetallizing heavy hydrocarbon oils it was found that the effect of hydrogen sulphide greatly depends on the hydrogen partial pressure and the total pressure applied. When the point of view is taken that the use of hydrogen sulphide in the demetallization is economically attractive in particular when, at a given total pressure, it results in a gain in demetallization activity of more than 50%, then it is found that both for the non-promoted catalysts and for the promoted catalysts this requirement can be met if the quantity of hydrogen sulphide is chosen such that the quotient PH2s/PH2 is equal to at least + 200 and at most PT + (PT)2 2PT-60 PT+60 (PH2, PH2S and PT represent the hydrogen partial pressure, the hydrogen sulphide partial pressure and the total pressure in bar, respectively.

Within the limits set by the formula the demetallization activity of the catalysts reaches an optimum value at a certain APHIS (P-H2S)- The value of P-H2S is different for the different catalysts and can be determined from some tentative experiments. Application of a PH2S above or below P-H)S but within the limits given still result in an increase of the demetallization activify by more than 50%, but this increase is smaller than the attainable maximum.

Obviously, during the demetallization process P-HNS or any other PH S may be controlled by continuously supplying a sufficient quantity of~hydrogen sulphide from an external source to the oil to be demetallized. However, from an economic point of view it is more attractive to utilize to the largest possible extent the hydrogen sulphide which is released in the demetallization process and/or in a desulphurization process carried out on hydrocarbonoil which has been treated according to the demetallization process. This consideration led to the following three attractive embodiments of the demetallization process according to the invention in the presence of additional hydrogen sulphide.

1) Application of gas recirculation in the demetallization process, the largest possible portion of hydrogen sulphide being left in the recirculating gas until the desired H PH)S is reached. A certain quantity of hydrogen sulphide is theruponcontinuously removed from the recirculating gas to maintain the desired hydrogen sulphide concentration.

2) In particular when a high PH S is desired, it may take a considerable time beore the hydrogen sulphide concentration in the recirculating gas has reached the desired value. This difficulty can be met by supplying hydrogen sulphide from an external source during the initial stage of the process and gradually reducing the supply of hydrogen sulphide as the process advances.

This additional quantity of hydrogen sulphide may, for instance, come from a hydrodesulphurization process.

3) Instead of gas recirculation to the demetallization reactor or in combination with it, offgas from a desulphurization reactor installed after the demetallization reactor is used as the feed gas for the demetallization reactor. A process scheme for a combined demetallization/desulphurization process in the presence of hydrogen, which scheme is based on the aforementioned principle, is shown in the attached figure and is further elucidated hereinafter.

The plant comprises successively a hydrodemetallization unit (1), a first gas-liquid separation unit (2), a hydrodesulphurization unit (3), a second gas-liquid separation unit (4) and a unit for the removal of hydrogen sulphide (5). A metal-and-sulphur-containing residual hydrocarbon oil (6) is subjected to hydrodemetallization together with two hydrogen- and hydrogen-sulphide-containing gas streams (7) and (8) and, if desired, with a hydrogen sulphide stream (9) from an external source. The product so obtained (10) is separated into a low-metal liquid stream (11) and a hydrogen- and hydrogen-sulphidecontaining gas stream (7), the latter being recycled to the demetallization unit. Liquid stream (11) is subjected to hydrodesulphurization together with a hydrogen-containing gas stream (12) and a hyrogen stream (13) from an external source. The product so obtained (14) is separated into a low-metal and low-sulphur liquid stream (15) and a hydrogen- and hydrogen-sulphide-containing gas stream (16), the latter being split into two portions (8) and (17) of the same composition. Portion (8) is recycled to the demetallization unit and portion (17), after removal of hydrogen sulphide, is recycled to the desulphurization unit as a gas stream (12).

The process according to the invention is preferably carried out by passing the hydrocarbon oils at elevated temperature and pressure and in the presence of hydrogen in an upward, a downward or a radial direction through one or more vertically disposed reactors containing a fixed or moving bed of the catalyst particles concerned. The process may, for instance, be carried out by passing the hydrocarbon oils together with hydrogen through a vertically disposed catalyst bed in an upward direction, the liquid and gas velocities applied being such as to cause the catalyst bed to expand (processing in ebullated bed operation). A very attractive embodiment of the process is one in which the hydrocarbon oil is passed through a vertically disposed catalyst bed, in which during operation fresh catalyst is periodically introduced at the top of the catalyst bed and spent catalyst is withdrawn at the bottom thereof (processing in bunker flow operation). Another very attractive embodiment of the process is one in which several reactors each containing a fixed catalyst bed are used. which reactors are alternately used for the process concerned; while the process is carried out in one or more of these reactors, the catalyst in the other beds is replenished (processing in fixed-bed swing operation). If desired, the process may also be carried out by suspending the catalyst in the hydrocarbon oil to be treated (processing in slurry phase operation).

The present catalysts are preferably used in the form of particles having a d of 0.5-4.0 mm and in particular of 0.6-3.0 mm.

The process according to the invention is preferably carried out at a temperature of 350-450"C, a hydrogen partial pressure of 25-200 bar and a space velocity of 0.1-10 kg.kg-1.h-I. Special preference should be given to the following conditions: a temperature of 375-425"C, a hydrogen partial pressure of 50-150 bar and a space velocity of 0.5-5 kg.kg-l.h-'. Hydrodemetallizing of metal-containing hydrocarbon oils is particularly important if the oil is subsequently subjected to catalytic cracking, hydrocracking or hydrodesulphurization. As a result of the hydrodemetallization deactivation of the catalysts used in these processes is suppressed to a considerable extent. Hydrocracking and hydrodesulphurization of hydrocarbon oils may be carried out by contacting the oils at elevated temperature and pressure and in the presence of hydrogen with a suitable catalyst which may be present in the form of a fixed bed, a moving bed or a suspension of catalyst articles. An attractive combination of demetallization accoding to the invention and hydrocracking or hydrodesulphurization is one in which the demetallization is carried out in fixed-bed swing operation or in bunker flow operation, while hydrocracking or hydrodesulphurization is carried out in conventional fixed-bed operation.

Examples of hydrocarbon oils having a total vanadium and nickel content of more than 500 ppmw which are eligible for demetallization according to the invention are crude oils and residues obtained in the distillation of crude oils such as topped crude oils, long residues and short residues.

The invention will now be elucidated with the aid of the following examples.

Example I Residual hydrocarbon oil having a total vanadium and nickel content of 1250 ppmw, which oil had been obtained after topping and dewatering of a crude oil from South America, was catalytically hydrodemetallized using six different non-promoted catalysts.

To this end the oil, together with hyrogen, was passed downwards through a cylindrical vertical disposed fixed catalyst bed at a temperature of 410"C, a hydrogen partial pressure (measured at the reactor inlet) of 150 bar, a space velocity of 2.1 kg of fresh feed per kg of catalyst per hour and a gas rate of 1000 N1 H2/kg of fresh feed. The liquid reaction product was split into two portions of the same composition in a volume ratio of 22:1. The smaller portion was removed from the system and the larger portion was recycled to the reactor inlet.

The results of the demetallization experiments together with the properties of the catalysts applied have been collected in Table A. For determining p and v as well as the total and nitroge pore volumes, use was made of the nitrogen adsorption/desorption method and of the mercury penetration method, as mentioned in British patent specification No. 1,430,645.

Table A Exp. Catalyst Surface Total Nitrogen v, % d, mm p, nm Vmax, K1.5, No. area, pore pore kg. kg-1.h. volume, volume m/g ml/g ml/g %w (ppmw V)- 1 SiO2 262 0.85 0.78 4 2.4 10 35 0.13 2 Al2o3 230 0.94 0.58 37 1.5 30 45 0.16 3 Al2O3 162 0.50 0.50 2 1.5 13 21 0.16 4 SiO2 130 0.75 0.65 5 2.4 20 23 0.14 5 Al2O3 144 0.30 0.22 23 2.4 48 17 0.06 6 SiO2-Al2O3 290 0.57 0.57 0 1.5 5 16 0.06 The performance of the catalysts is assessed on the basis of Vmax and K1.5. Vmax is the maximum quantity of vanadium, expressed in %w on fresh catalyst, which the catalyst particles can absorb in their pores and K1:5 is the activity of the catalyst, expressed in kg.kg-1.h-l. (ppmw V)- , after half the catalyst life (in terms of quantity of vanadium absorbed) has elapsed. K1.5 is calculated with the formula k1.5 = (space velocity in kg.kg-1.h-1) x ppmw V in feed - ppmw V in product (ppmw V in product)1 The performance of a catalyst is rated good under the conditions applied in this demetallization of the criteria are met that Vmax is larger than 30 %w and that K1.5 is larger than 0.08 kg.kg-1.h-1. (ppmw V)-.

Experiments 1 and 2 in which the above requirements with respect to Vmax and k1.5 were satisfied, are demetallization experiments according to the invention. In Experiment 1, in which a catalyst was used with 10-0.15 v > p/d > 3.5-0.02 v, this catalyst also met the additional requirements of the invention with respect to total pore volume ( > 0.40 ml/g), v ( < 50%), nitrogen pore volume ( > 0.0 ml/g), surface area ( > 150 m2/g) and p ( > 5 nm). In Experiment 2, in which a catalyst was used with p/d > 1)-0.15 v, this catalyst also met the additional requirements of the invention with respect to total pore volume ( > 0.40 ml/g), v ( < 50%) and surface area ( > 100 m2/g).

Experiments 3-6, in which the above requirements with respect to Vmax and K1.5 were not met, are demetallization experiments outside the scope of the present invention. In Experiment 3 a catalyst was used with 10-0.15 > pld > 3.5-0.02 v, but with a nitrogen pore volume of less than 0.60 m-/g. In Experiment 4 a catalyst was used with 10-0.15 v > p/d > 3.5-0.02 v, but with a surface area of less than 150 m2/g. In Experiment 5 a catalyst was used with p/d > 10-0.15 v, but with a total pore volume of less than 0.40 ml/g. In Experiment 6 a catalyst was used with p/d > 3.5-0.02 v.

Example II Experiment 1 of Example I was repeated several times, each time with application of a different hydrogen sulphide partial pressure. In these experiments hydrogen sulphide was added from an external source. In all experiments a constant total pressure (measured at the reactor inlet) of 150 bar was applied. The results of these experiments have been collected in Table B.

Table B Exp. PH2, PH2S, k1.5, Gain kg.kg-1.h-1 in k1.5, No. bar bar (ppmw V)- % 1 150 0 0.13 7 148 2 0.16 23 8 142 8 0.21 62 9 130 20 0.29 123 10 90 60 0.20 54 In Experiments 8-10 a PH2s/PH2 was applied satisfying the relation ## + ####2 # PH2S/PH2 # and a gain in demetallization activity of more than 50% was reached. In Experiment 7 a PH2s/PH was applied which did not satisfy the above-mentioned relation and a gain in demetallization activity was obtained which was smaller than 50%.

Claims

WHAT WE CLAIM IS:

1. A process for demetallizing hydrocarbon oils, characterized in that a hydrocarbon oil with a total vanadium and nickel content of more than 500 ppmw is contacted, at elevated temperature and pressure and in the presence of hydrogen, with a non-promoted catalyst meeting the following requirements: (1) p/d > 3.5-0.02 v, in which p is the specific average pore diameter in nm, d is the specific average particle diameter in mm and v is the percentage of the total pore volume that consists of pores with a diameter larger than 100 nm, (2) the total pore volume is larger than 0.40 ml/g, (3) v is smaller than 50%, and (4) the specific surface area is larger than 100 m2/g; for the case that the catalyst has such a p and d that the quotient p/d is not larger than 10-0.15 v, the catalyst meets the following additional requirements: (a) the nitrogen pore volume is larger than 0.60 ml/g, (b) the specific surface area is larger than 150 m2/g, and (c) p is larger than 5 nm.

2. A process according to claim 1, characterized in that as the catalyst is used an oxide of an element of Group, II, III or IV or a mixture of the said oxides.

3. A process according to claim 2, characterized in that as the catalyst silica, alumina or silica-alumina is used.

4. A process according to any one of claims 1-3, characterized in that catalysts are used having a d of 0.5-4.0 mm and preferably of 0.6-3.0 mm.

5. A process according to any one of claims 1-4, characterized in that it is carried out in bunker flow operation or in fixed-bed swing operation.

6. A process according to any one of claims 1-5, characterized in that it is carried out with addition of hydrogen sulphide.

7. A process according to claim 6, characterized in that it is carried out in the presence of such a quantity of hydrogen sulphide that the quotient PH2S/PH2 satisfies the relation: p:F+ TFF2 6 PH2S/PH26 -FT+28 where PH2, PH2S and PT represent the hydrogen partial pressure, the hydrogen sulphide partial pressure and the total pressure in the bar, respectively.

8. A process according to claim 6 or 7, characterized in that in the process use is made of hydrogen sulphide which is released in the demetallization process and/or in a desulphurization process carried out on hydrocarbon oil which has been treated according to the demetallization process.

9. A process according to claim 8, characterized in that gas recirculation is applied in the demetallization process, the largest possible portion of hydrogen sulphide being left in the recirculating gas until the desired PH S is reached, after which a certain quantity of hydrogen sulphide is continuously removed from the recirculating gas to maintain the desired hydrogen sulphide concentration.

10. A process according to claim 9, characterized in that during the initial stage of the process hydrogen sulphide from an external source is supplied to the process and that the quantity of the hydrogen sulphide supplied is gradually reduced as the process advances.

11. A process according to claim 8, characterized in that a metal and a sulphur containing residual hydrocarbon oil is subjected to hydrodemetallization together with two hydrogen- and hydrogen-sulphide-containing gas streams (A and B) and, if desired, with a hydrogen sulphide stream from an external source, that the product obtained is separated into a low-metal liquid stream and a hydrogen-and hydrogen-sulphide-containing gas stream, the latter being recycled as gas stream A to the demetallization reactor, that the low-metal liquid stream together with a hydrogen-containing gas stream (C) and a hydrogen stream from an external source are subjected to hydrodesulphurization, that the product obtained is separated into a low-metal and low-sulphur liquid stream and a hydrogen- and hydrogen-sulphide-containing gas stream, the latter being split into two portions of the same composition, that one of these portions is recycled to the demetallization reactor as gas stream B and that the other portion after removal of hydrogen sulphide is recycled to the desulphurization reactor as gas stream C.

12. A process for the catalytic conversion of metal-containing hydrocarbon oils by cracking, hydrocracking or hydroesulphurization, the oil first being demetallized and then being catalytically converted, characterized in that the demetallization is carried out according to any one of claims 1-11.

13. A process according to any one of claims 1-12, characterized in that the catalytic conversion is carried out at a temperature of 350-450 C, a hydrogen partial pressure of 25-200 bar and a space velocity of 0.1-10 kg.kg-l.h-l.

14. A process according to claim 13 characterized in that the catalytic conversion is carried out at a temperature of 375-425"C, a hydrogen partial pressure of 50-150 bar and a space velocity of 0.5-5 kg.kg-l.h-l.

15. A process for demetallizing hydrocarbon oils substantially as described hereinbe