CA1116582A

CA1116582A - Process for extracting vanadium from deactivated catalysts

Info

Publication number: CA1116582A
Application number: CA000296567A
Authority: CA
Inventors: Willem H.J. Stork
Original assignee: Shell Canada Ltd
Current assignee: Shell Canada Ltd
Priority date: 1977-03-24
Filing date: 1978-02-09
Publication date: 1982-01-19
Also published as: IT1093669B; FR2384854A2; DE2812597A1; SE7803322L; SU688108A3; IT7821453A0; BE864852R; JPS53119209A; SE444581B; NO152939C; NL7703181A; ZA781661B; AU516502B2; NO152939B; JPS637819B2; FR2384854B2; GB1567140A; NO781027L; AU3443578A; MX147986A

Abstract

ABSTRACT

A process for recovering vanadium from a deactivated catalyst in which process a catalyst which has become deactiv-ated in the catalytic hydrotreatment of a vanadium-containing hydrocarbon oil is treated with a mixture of steam and air under specified conditions followed by extraction with an aqueous solution of a mineral acid in the presence of a reduc-ing agent, after which vanadium is isolated from the vana-dium-containing solution thus obtained.

Description

The Calladi~n application 233,512 filed Au~gust 15, 1975 relates to a process for extracting vanadiu~. from a catalyst which has been deactivated by use in the treatment o~ a hydrocarbon oil containing vanadium with hydrogen at elevated temperature and pressure, during which treatment the vanadium content of the catalyst has increased by at least 1G pbw. According to the said application 233,512 the extraction of the vanadium, whereby the vanadium content o~ the catalyst is decreased by at least 40%
of the amount by which it has risen during the deactivation, is carried out by extracting the deactivated catalyst with an aqueous solution of a mineral acid, after which vanadium is separated from the vanadium-containing solution thus obtained.
If the process is applied to a catalyst that has been deactiv-ated in the hydrotreatment of a hydrocarbon oil containing nickel in addition to vanadium, during which treatment the nickel content of the catalyst has increa~sed as well, nickel is also removed ~rom the catalyst in the process. Besides the extraction of vanadium and optionally nickel from deactivated catalysts, the process is also applicable to the regeneration of deactivated catalysts so that they can be used again for catalytic purposes.
According to the said application 233,512 the acid extraction is preferably carried out in the presence of a reducing agent. Also, according to the said application 233,512 it is preferred to treat the deactivated catalyst first with steam to remove sulphur and then with an oxygen con-taining gas to remove carbon~ prior to subjecl ~g it to acid extraction. It ~hou~d be r~marked that, when the aim is not only to exkract vanadium and optionally nickel from the cata-lyst, but also to regenerate the catalyst, the treatment of the deactivated catalyst with an oxygen-containing gas in the way indicated in the examples o~ the said application 233J512 whereby a small portion of the deactivated catalyst is treated with air for three hours at 550C, is not suitable for larger quantities of deactivated catalyst because of the large amount of heat that would be liberated.
When larger quantities of deactivated catalyst had to be treated with a view to extracting vanadium and optionally nickel from the catalyst as well as regenerating the catalyst, the following three-stage procedure was until recently con-sidered to be the most attractive embodiment of the process according to the said application 233~512 The deactivated catalyst is first treated for 1-5 hours at 250--450C and atmospheric pressure with a mixture of steam and nitrogen, then for 1-5 days at 350-600C and atmospheric pres-sure with a mixture of air and nitrogen and finally it is subjected to acid extraction in the presence of a reducing agent for 0.5-3 hours at 50-150C. The treatment times required in the various stages are dependent upon, inter alia, the quantities of sulphur, carbon and metabs which are present on the deactivated catalyst and the conditions chosen, vi~. treat-ment temperatures, gas flow rates and compositions of treating gases and extraction liquid. Up to now the long treatment time required in the second stage of the three-stage procedure has been considered a serious drawback for using the process according to the said application 233~512 on a commercial scale.
Continued investigation of the process as described in the said application 233,512 has now led to the finding that a comparable res~llt can be obtained as regards vanadium and nickel removal and activity of the regenerated catalyst to that achieved by conducting the process according to the three-stage procedure described hereinbefore, but in a much shorter time, if the acid extraction in the presence of a reducing agent is preceded by treatment of the deactivated catalyst at a temperature above 250C with a mixture of steam and air of which the steam~air ratio is more than 1.0 at a ~team partial pressure above 1 bar. In addition to the fact that with the process now found a much shorter treatment time will suffice for achieving a comparable result as regards vanadium and nickel removal and activity of the regenerated catalyst, this proceqs has two additional advantages over the abov~-mentioned three-stage procedure in that both the number of treatment stages and the number of gases necessary for treating the deactivated catalyst prior to the acid extraction have decreased by one.
The present patent application therefore relates to an improved process for extracting vanadium from a deactivated catalyst according to the said application 233,512 in which process vanadium is extracted from a catalyst which has been deactivated by use in the treatment of a vana-5 _ dium-containing hydrocarbon oil with hydrogen at elevated temperature and pressure, during which treatment the vanadium content of the catalyst has increased by at least 10 pbw, and in which process the said vanadiu~ extraction, whereby the vanadium content Or the catalyst is reduced by at least 40% of the amourt by which it has risen during the deactivation (vana-dium content of the catalyst expressed in pbw vanadium/100 pbw catalyst carrier~, i9 carried out by extracting the deactivated catalyst with an aqueous solution of a mineral acid (called hereinafter "acid extraction"), after which the vanadium is separated from the vanadium-containing solution thus obtained.
The improvement consists in that the acid extraction which is carried out in the presence of a reducing agent, is preceded by a treatment of the deactivated catalyst at a temperature above 250C with a mixture of steam and air in which the steam/air ratio is more than 1.0 at a steam partial pressure above 1 bar.
In the process according to the present invention the treatment with the mixture of steam and air should be conducted at a temperature above 250C, but preferably below 600C and in particular at a temperature between 325 and 425C. In the treatment of the deactivated catalyst with the mixture of steam and air the steam partial pressure should be more than 1 bar, but preferably below 5 bar and in particular between 2 and 4 bar. The steam/air ratio of the steam/air mixture used should be more than 1.0, but preferably lower than 10 and in partic-ular between 4 and 8.
The acid extraction in the presence of a reducing agent to 8;~

which the deactivated catalyst should be subjected in the process according to the inventionS i9 preferably carried out at elevated temperature, in particular at a temperature above 50C. The said extraction is preferably conducted with an aqueous solution of sulphuric acid which has been saturated with sulphur dioxide.
When the process according to the invention is applied to deactivated catalysts which contain nickel in addition to vanadium, it may be advisable to extract the deactivated cata-lyst with water after the treatment with the steamJair mixture.By this extraction with water, which is preferably carried out at elevated temperature and in particular at a temperature above 50C, an aqueous nickel-containing solution is obtained ~rom which the nickel can be extracted.
The process according to the presellt invention is partic-ularly important in those cases in which the aim is not only to extract vanadium and optionally nickel from the deactivated catalyst, but also to regenerate the catalyst (which may, in the fresh condition, contain one or more metals with hydrogen-ation activity) so that it can be used again for catalytic purposes. The present patent application relates therefore not only to a process for extracting vanadium and optionally nickel from a deactivated catalyst, but also to a process in which this extraction is conducted in such a way that a regenerated catalyst is obtained which can be used again Por catalytic purposes, either as such, or after a complementary quantity of metals with hydrogenation activity has been added to it. The process according to the invention is especially important for extracting vanadium and optionally nickel from a catalyst substantially consisting of silica, in combination with re-generation of the catalyst, which catalyst has been u~ed in a proces~ for the hydrodemetallization of a hydrocarbon oil.
The invention will now be explained with reference to the following examples.

EXAMPLE_I

A catalyst comprising 0.5 pbw nickel and 2.0 pbw vanadium per 100 pbw silica carrier was prepared by impregnat;ng a silica carrier with an aqueous solu~ion of nickel nitrate and vanadyl oxalate, after which the composition was dried and calcined. The catalyst (catalyst A) was used in the sulphidic form for the hydrodemetallization of a hydrocarbon oil (oil A) with a total vanadium and nickel content of 62 ppmw, a C5-as-phaltenes content of 6.4 ~w and a sulphur content of 3.9 %w, which oil had been obtained as the residue in the atmospheric distillation of a crude oil from the Middle East. The hydrode-metallization was carried out by passing the oil together with 20 hydrogen in a downward direction through a cylindrical, ver- !

tically disposed fixed catalyst bed at a temperature of 420C, a total pressure of 150 bar, a spaoe velocity of 5 kg.l 1.h 1 and a gas flow rate (measured at the reactor outlet) of 250 Nl H2.kg 1. The activity of the catalyst, expressed as "% vanadium removed" (= average vanadium removal over the period of cata-lyst age from 1 tonne oil/kg catalyst to 4 tonnes oil/kg cata-lyst), was 51. After the catalyst had been deactivated in this S8~

process, it was extracte(! with toluene to remove remnants of residual oil and after evaporation of the toluene from the catalyst the latter was analysed. The deactivated catalyst (catalyst B) contained 9.7 pbw carbon, 20.6 pbw sulphur, 4.1 pbw nickel and 24.3 pbw vanadium per 100 pbw silica.

EXAMPLE II
5 kg of Catalyst B was treated with a 4:1 steam/nitrogen mixture for three hours at 350C, atmospheric pressure and a gas flow rate of

2 Nl gas mixture~(g catalyst) 1.h-1. The catalyst was then treated with a 1:19 air/nitrogen mixture for 50 hours at 400C, atmos-pheric pressure and a gas flow rate of 1 Nl gas mixture (g catalyst) 1.h 1. Finally, the catalyst was extracted for two hours at 90C with stirring with 40 l 2 N sulphuric acid which had been saturated with sulphur dioxide~ After the extracted catalyst had been washed with water, it was dried at 120C and calcined for three hours at 550C. On analysis of the catalyst thu~ obtained (catalyst C), 96% of the vanadium and 95% of the nickel were found to have been removed from the catalyst by this treatment.

EXAMPLE III

5 kg of Catalyst B was treated with a 7:1 steam~air mix-ture for 25 hours at 400C, a steam partial pressure of 3.5 bar and a gas rate of 0.6 Nl gas mixture. (e catalyst) 1.h 1. The catalyst was then extracted for two hours ~t 90C with stirring with 40 l 2 N sulphuric acid which had been saturated with sulphur dioxide. After the extracted catalyst had been washed with water, it was dried at 120C and calcined for three hours X~

at 550C. On analysis Or the catalyst thus obtained (catalyst D), 96% of the vanadium and 95% of the nickel were found to have been removed from the catalyst by this treatment.
EXAMPLE IV
5 kg of Catalyst B was treated with a 5:1 steam/air mix ture for 20 hours at 350C, a steam partial pressure of 3.0 bar and a gas flow rate of 0.6 Nl gas mixture.(g catalyst) 1.h 1.
The catalyst was then subjected to acid extraction in the same way as described in Example III. On analysis of the catalyst thus obtained (catalyst E), 94% of the vanadium and 92% of the nickel were found to have been removed from the catalyst by this treatment.
EXAMPL V
5 kg of Catalyst B was treated with a 1:2 steam/air mix-ture for 20 hours at 400C, a steam partial pressure of 0.6 bar and a gas flow rate of 0.4 Nl gas mixture.(g catalyst) l.h 1.
The catalyst was then subjected to acid extraction in the same way as described in Example III. On analysi3 of the catalyst thus obtained (catalyst F), 95% of the vanadium and 95% of the nickel were found to have been removed from the catalyst by this treatment.
EXAMPLE VI
5 kg of Catalyst B was treated with a 2:1 steam/air mix-ture for 25 hours at 150C, a steam partial pressure of 1.5 bar and a gas ~low rate of 2 Nl gas mixture.(g catalyst) .h 1. The catalyst was then subjected to acid extraction in the same way 8;2 as de.scribed in Example ll`i. On analysis of the catalyst thus obtained (catalyst C), 40~ of the vanadiu~ and 45g of the nickel were found to have been removed from the catalyst by this treatment.

EXAMPLE VII
Catalysts containing 0.5 pbw nickel and 2.0 pbw vanadium per 100 pbw silica carrier were prepared by impregnating cata-lysts C and F with an aqueous solution of nickel nitrate and vanadyl oxalate, after which the compositions were dried and calcined. Catalysts C' and F' thus obtained were used in the sulphidic form for the hydrodemetallization of oil A under the same conditions as the hydrodemetallization of this oil by catalyst A dèscribed in Example I. The activities of catalysts C' and F', expressed as "percentage vanadium removed", were 48 and 10, respectively.

EXAMPLE VIII
In the same way as described in Example VII, catalysts D' and E' were prepared from catalysts D and E and usec for the hydrodemetallization of oil A. The activities of catalysts D
and E', expressed as "percentage vanadium removed", were 50 and 49, respectively.
0f the examples I-VIII, Nos. III, IV and VIII are examples according to the present invention. The other examples have been included for comparison.

Example I relates to a hydrodemetalli~ation in which a fresh catalyst A deactivates to the deactivated catalyst 3.

Example II relates to the three-stage procedure described hereinbe~ore in which a regenerated catalyst C is prepared from the deactivated catalyst B and in which it takes 53 hours in all to carry out the first two stages~
Examples III and IV relate to the improved process accord-ing to the invention in which regenerated catalysts D and E are prepared from the deactivated catalyst B. Comparison of exam-ples II, III and IV shows that the process according to the invention leads to the same excellent metal removal as the three-stage procedure. However, the treatment with the steam/air mixture, which has replaced the first and the second stage of the three-stage procedure, takes only 20-25 hours.
Examples V and Vl relate to the treatment of the deactiv-ated catalyst with a mixture of steam and air followed by acid extraction, in which "regenerated" catalysts F and G are pre-pared from deactivated catalyst B. During the treatment with the steam/air mixture. the steam partial pressure and the steam/air ratio employed were too low in Example V and the temperature was too low in Example VI. This resulted in an 2~ insufficient metal removal for catalyst G (and consequently in a low activity!) and, as is seen from Example VII, in a low activity for catalyst F.
From Examples VII and VIII it is seen that catalysts which have been regenerated according to the present invention (cata-lysts D' and E') show the same high activity as a catalyst which has been regenerated according to the three-stage pro-cedure (catalyst C').

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An improved process for extracting vanadium from a deactivated catalyst which has been deactivated by use in the treatment of a vanadium-containing hydrocarbon oil with hydrogen at elevated temperature and pressure, during which treatment the vanadium content of the catalyst has increased by at least 10 pbw, said process comprising treating the deactivated catalyst at a temperature above 250°C with a mixture of steam and air in which the steam/air ratio is more than 1.0 at a steam partial pressure above 1 bar, carrying out acid extraction in the presence of a reducing agent by extracting the deactivated catalyst with an aqueous solution of a mineral acid, after which the vanadium is separated from the vanadium containing solution thus obtained, the vanadium content of the catalyst is reduced by at least 40%
of the amount by which it has risen during the deactivation (vanadium content of the catalyst expressed in pbw vanadium/100 pbw catalyst).

2. A process according to claim 1, characterized in that the treatment of the deactivated catalyst with a mixture of steam and air is conducted at a temperature below 600°C.

3. A process according to claim 2 wherein said temperature is between about 325 and 425°C.

4. A process according to claim 1, characterized in that the treatment of the deactivated catalyst with a mixture of steam and air is conducted at a steam partial pressure below 5 bar.

5. A process according to claim 4 wherein said steam partial pressure is between about 2 and 4 bar.

6. A process according to claim 1, characterized in that the treatment of the deactivated catalyst with a mixture of steam and air is conducted with a gas mixture in which the steam/air ratio is lower than 10.

7. A process according to claim 6 wherein said steam/air ratio is between about 4 and 8.

8. A process according to claim 1, characterized in that the acid extraction in the presence of a reducing agent is carried out at a temperature above 50°C.

9. A process according to claim 1, characterized in that the acid extraction in the presence of a reducing agent is carried out with an aqueous solution of sulphuric acid which has been saturated with sulphur dioxide.

10. A process according to claim 1, characterized in that nickel is removed from the deactivated catalyst by extraction with water at a temperature above 50°C, after the deactivated catalyst has been treated with the steam/air mixture.