Process for hydrotreating heavy hydrocarbons in the presence of a molybdenum containing catalyst

Process for hydrogenating a heavy hydrocarbon charge containing asphaltenes, in the liquid phase, in the presence, as catalyst, of a molybdenum blue solution in a polar organic solvent soluble in the charge, so as to remove impurities therefrom before subjecting it to further refining.

BACKGROUND OF THE INVENTION 
This invention concerns the field of petroleum refining and, more 
specifically, processes for converting by hydrogenation heavy crude oils, 
heavy hydrocarbon cuts and petroleum residues. 
The feed charge used in the process of this invention may consist of any 
heavy hydrocabon oil of high boiling point, for example an oil of which at 
least 80% by weight of the components have a boiling point above 
350.degree. C. The initial oil source may be any hydrocarbon deposit of 
old origin including, besides crude oil, such materials as shale oil or 
oil extracted from oily sands, or liquid hydrocarbons obtained by 
liquefying coal or any hydrocarbon mixture containing undesirable 
compounds. 
The crude oil and the petroleum cuts are very complex mixtures where, in 
addition to the hydrocarbons, are present various undesirable compounds 
containing sulfur, nitrogen, oxygen and/or metals. The amount and the 
nature of the compounds vary in accordance with the origin of the crude 
oil and the considered cuts. Generally these impurities are detrimental to 
a good quality of the petroleum products in view of their pollution or 
corrosion effect, of their odor and/or unstability, or because they make 
very difficult the refining operations and, particularly, the conversion 
to light products, since they may deactivate the catalysts used in these 
conversions such as, for example, the catalytic cracking or hydrocracking 
catalysts. 
The treatment of these charges is made difficult by the presence of 
asphaltenes and of metals which, under insufficiently controlled 
conditions, result in the deactivation of the catalysts. 
The contaminating metal agents may be present as oxides or sulfides, but 
usually they consist of organometallic compounds such as porphyrines and 
their derivatives which are associated to the asphaltenes and to the 
resins, the most common metals being vanadium and nickel. 
The asphaltenes are essentially in the form of a colloidal suspension 
which, under the hydrorefining conditions, may agglomerate and form a 
deposit on the catalyst composition. Consequently, the fixed-bed 
hydrotreatment of these charges does not produce satisfactory results 
inasmuch as the catalyst deactivates as a result of coke and metal 
deposition. 
A technique for obviating these deficiencies, by providing a better access 
of high molecular weight asphaltenes to the catalyst sites, is disclosed 
in several patents, for example the French Pat. No. 1 373 253 or the U.S. 
Pat. No. 3,165,463. 
For this purpose, there are used catalytically active metal compounds, in 
extremely divided particles, used as a colloidal suspension or dissolved 
in a solvent. When they are introduced into the charge, they are converted 
to sulfides and, in the course of the hydrorefining treatment, there is 
formed a sludge containing the catalyst, asphaltenes and various metal 
impurities. 
It is known to make use as catalytic active agent of a compound of a metal 
selected from groups II to VIII and, more particularly, from groups IV, V 
and VI and the iron group. Among the metals of these latter groups, 
molybdenum is particularly to be mentioned, either alone or in joint use 
with a metal of the iron group, for example as ammonium heptamolybdate, 
phosphomolybdic acid, a molybdenum organic salt or molybdenum blue. 
DETAILED DISCUSSION 
The present invention relates to a process for hydrotreating heavy 
hydrocarbons, in the liquid phase, in the presence of a dispersed 
catalyst. More particularly, it concerns a hydroconversion process wherein 
a liquid phase of hydrocarbon oil containing in a dispersed state a 
particular molybdenum blue catalyst, is reacted with hydrogen. This 
treatment is conducted with the purpose of removing sulfur, nitrogen, 
metals (particularly Ni, V, Na, Fe, Cu), asphaltenes and resins contained 
in the charge, these removals resulting in a simultaneous reduction of the 
Conradson carbon. 
The U.S. Pat. No. 3,169,919 discloses a hydroconversion process wherein a 
hydrocarbon charge is contacted with colloidal molybdenum blue, prepared, 
for example, according to the method described in Journal of the American 
Chemical Society, Vol. 64, page 2543-2545 (1945). The molybdenum blue 
prepared according to this method is extracted by means of a solvent such 
as an alcohol. The resulting solution is admixed with the hydrocarbon 
charge to be refined, the solvent is expelled so that the molybdenum 
compound appears in a colloidal form and it is only at this stage that the 
hydrorefining step is performed. 
It has now been found that a hydroconversion process making use of a 
molybdenum blue catalyst soluble in hydrocarbons, prepared according to a 
specific method, offers advantages which will be made apparent 
hereinafter. 
There is used, according to the invention, as hydrorefining catalyst, a 
molybdenum blue solution in a polar organic solvent, preferably a solvent 
whose normal boiling point is relatively high, higher than 140.degree. C. 
This feature distinguishes the present process from that of U.S. Pat. No. 
3,169,919 according to which the alcohol was expelled to form a colloidal 
precipitate of molybdic complex, before the performance of the 
hydrorefining step. 
This solution may be obtained by extracting the molybdenum blue from the 
aqueous solution where it has been formed, by means of a polar solvent not 
entirely miscible with water, for example a solvent whose solubility in 
water at 20.degree. C. is less than 10% by weight. It is also possible to 
operate with a fresh precipitate of molybdenum blue and to extract the 
latter with a polar solvent, as described in U.S. Pat. No. 3,169,919. 
The molybdenum blue solution in a polar organic solvent, such as defined 
hereinafter, then forms a solution miscible with the hydrocarbon to be 
treated. Thus, when admixed with a heavy gas oil or a fuel oil, in a 
proportion of, for example, 5% of molybdenum in the mixture, it may be 
filtered without forming on the filter more deposits than those observed 
with the hydrocarbon fraction to be treated without the addition of 
molybdenum blue solution. 
This feature distinguishes the present process from that of U.S. Pat. No. 
3,169,919 which makes use of a colloidal precipitate and forms deposits in 
the filtration step. 
By polar organic solvent, it is meant a compound whose molecule contains 
carbon, at least one heteroatom selected preferably from O, S, N, P and 
optionally also hydrogen. It is soluble in a proportion of at least 1% in 
the hydrocarbons under the conditions of the hydrorefining reaction. 
By way of example, and provided that the above-mentioned partial 
immiscibility condition is fulfilled, there can be mentioned, as 
convenient solvents, alcohols, ethers, ketones, esters, phosphoric esters 
and amides, sulfuric esters, amides and nitriles. 
However, the solvents containing only oxygen as heteroatom are preferred, 
in order to avoid the supply of elements similar to those which are to be 
removed. 
Preference is given to alcohols having from 4 to 20 carbon atoms in the 
molecule, particularly 6 to 18 carbon atoms, such, for example, as 
isobutanol, isopentanol, C.sub.8 -C.sub.12 OXO alcohols, cyclohexanol or 
benzyl alcohol. The alcohols boiling above 150.degree. C. are preferred. 
It is obviously desirable that at least one portion of the alcohol be kept 
in the liquid phase under the hydrorefining conditions. However this is 
not obligatory and the mere introduction of molybdenum blue into the 
hydrocarbon charge as a solution in a polar solvent boiling above 
140.degree. C., is sufficient for obtaining improved results. 
It is assumed that the heavy solvent stabilizes the molybdenum blue 
solution up to a temperature which enables the stabilization of the blue 
by the hydrocarbon charge itself, particularly by the asphaltene/resin 
fractions of said charge. This stabilization is maintained even when, 
during heating, the solvent partly or totaly vaporizes. 
The concentration of the molybdenum blue solution in the polar solvent may 
be selected within a wide range, for example from 0.1 to 50%, preferably 
from 5 to 40% by weight, calculated as molybdenum. 
The molybdenum blue in aqueous solution may be formed by mere reduction of 
an aqueous solution of molybdic acid or of an alkali metal molybdate. The 
operation is preferably conducted in acidic medium, for example in the 
presence of sulfuric acid or phosphoric acid. Hydrochloric acid is usually 
less desirable, since it leads to a partial precipitation of molybdenum. 
Any reducing agent may be used, such for example as nascent hydrogen, 
H.sub.2 S, SO.sub.2, a redox system such as SnCl.sub.2, a molybdenum salt 
of lower valency or, preferably, hydrazine. An electrolytic reduction may 
also be used. 
The pH is advantageously lower than or equal to 4. 
An excess of strong acid such as sulfuric acid usually facilitates the 
passage of the molybdenum blue from the aqueous solution to the organic 
solution. The pH is then preferably at most equal to 2. 
The molybdenum blues are compounds whose structure is not well defined. 
According to certain authors, they consist of molybdenum oxides having an 
apparent valency lower than 6 and higher than 3. 
The starting molybdate solution may contain other salts, preferably 
phosphates, as described for example in the French Pat. No. 1 099 953; it 
is also possible to start with an heteromolybdate, such for example as a 
phosphomolybdate. The molybdenum blue may then contain heteroatoms, for 
example phosphorus. The invention is however not limited to the use of a 
particular molybdenum blue. 
The operation according to the French Pat. No. 1 099 953 consists of 
reducing an acidified aqueous solution of alkali metal heptamolybdate, 
then extracting it with isobutyl alcohol or with an ether, adding to the 
resulting isobutyl alcohol or ether solution a higher alcohol having 
preferably from 6 to 12 carbon atoms, removing the isobutyl alcohol or the 
ether by evaporation and partially removing the higher alcohol by vacuum 
distillation up to a concentration of the resulting molybdenum complex 
from 15 to 40% (as molybdenum). The solvent must not be completely removed 
since otherwise the complex would no longer be soluble in the 
hydrocarbons. The higher alcohol is preferably an OXO alcohol or a mixture 
of OXO alcohols or an Alfol. 
It is particularly advantageous to add at least one compound of the iron 
group, preferably as a compound soluble in organic medium, to the 
molybdenum blue catalyst solution obtained according to the described 
method. This compound may be selected, for example, from metal salts of 
organic acids as well as from metal complexes whose ligand is an oxygen-, 
nitrogen-, sulfur-or chlorine-containing organic compound. The preferred 
soluble compounds are oleates, stearates, octoates, naphthenates, 
acetylacetonates or ethylhexanoates. The preferred metals from the iron 
group are cobalt and nickel. 
The hydrotreatment reaction is usually conducted at a temperature from 
250.degree. to 450.degree. C. and a pressure from 50 to 200 bars. In case 
of continuous operation, the feed rate of the hydrocarbon charge is 
usually from 0.1 to 10 volumes per volume of reaction space and per hour. 
The hydrogen flow rate is, for example, from 50 to 5000 liters per liter 
of hydrocarbon liquid charge. 
The catalyst according to the invention is used in a proportion of, for 
example, from 0.001 to 5% by weight, calculated as molybdenum, with 
respect to the hydrocarbon charge. 
When a metal from the iron group is present, the atomic ratio of this metal 
to molybdenum is, for example, from 0.1:1 to 10:1. 
The process of the invention may be conducted in any convenient manner, for 
example, as a continuous process or batchwise. 
The fresh catalyst is introduced into the fresh hydrocarbon charge as a 
solution in a polar solvent. 
When the soluble compounds are added to the hydrocarbon charge, they first 
dissolve therein and, subsequently, maintain their catalytic activity even 
when converted, after a certain time under the hydroconversion conditions, 
to metal compounds dispersed in the treated hydrocarbon. 
The continuous performance of the process requires that the heavy 
hydrocarbons and the catalyst sludge be separated from the total product 
discharged from the reaction zone. This operation is conducted by any 
convenient means, for example by distillation, decantation, 
centrifugation, hydrocycloning or by any other means known in the art. It 
is particularly advantageous to separate the sludge by adding a diluent to 
the mixture, which makes the separation easier. For this purpose, there 
can be used a hydrocarbon or a hydrocarbon oil distillation cut. 
Preferably, there is used an aromatic fraction or a fraction containing a 
high proportion of aromatic compounds such as benzene, toluene, 
polyalkylaromatic hydrocarbons or mixtures of aromatic compounds or even 
petroleum cuts having a high content of aromatic compounds, such as light 
recycle oils from catalytic cracking (light cycle oil), aromatic extracts 
from oil manufacture or heavy gas oils from steam-cracking. 
After separation, the sludge may be washed with a solvent, preferably an 
aromatic solvent selected from the above-mentioned list of solvents. Then, 
the sludge may be recycled, preferably after washing, so as to be combined 
with a new hydrocarbon charge. Periodically or continuously, there is 
withdrawn a portion of said sludge, as catalyst purge and it is replaced 
by a substantially equivalent amount of fresh catalyst components, so that 
the metal catalyst content of the treated charge be, for example, from 
0.01 to 5% by weight. As a matter of fact, during the treatment, the 
organo-metallic compounds which provide for the solubilization of the 
metals in the hydrocarbon phase are partially destroyed. The metals 
contained therein accumulate in the catalyst-containing sludge. This 
nickel and vanadium accumulation in the catalyst-containing sludge 
contributes to the slow deactivation of the latter and makes desirable the 
purge of a portion of the catalyst and its replacement by an equivalent 
amount of fresh catalyst. 
The sludge containing the catalyst and the deposited metals, mainly nickel 
and vanadium, is fed to a treatment system operated according to 
techniques known in the art, whereby nickel, vanadium, molybdenum and 
optionally cobalt may be recovered. A portion of these metals may be 
reshaped to manufacture catalyst according to the invention by making use 
of suitable transformation systems.

The following examples are given for illustrative purpose and cannot be 
considered as limiting in any manner the scope of the invention. 
EXAMPLE 1 
Test No. 1 
55.8 g of pure ammonium paramolybdate and 1350 cc of distilled water are 
introduced into a glass Grignard reactor of 2 liters capacity, heated by 
means of an electric flask heater and equipped with a stirrer of the 
propeller type, a condenser and a thermometer. The mixture is stirred up 
to complete dissolution of the molybdenum salt and then 407 g of H.sub.2 
SO.sub.4 at a 98% by weight concentration are slowly added. 
There is subsequently added, while stirring, 63 g of HNa.sub.2 
PO.sub.4.12H.sub.2 O. The reactor content is then brought to boiling and 
48 cc of an aqueous solution of hydrazine hydrochloride at a 6% by weight 
concentration are then added. 
The aqueous solution of molybdenum blue thus obtained is divided into 3 
equal portions. 
The first aqueous portion is extracted with 600 cc of isobutyl alcohol; the 
solution is settled so as to recover the supernatent alcohol phase, and 
this alcoholic phase of molybdenum blue is used again to extract the 
second and then the third aqueous fraction. 
After extraction, the alcoholic phase is dried with anhydrous Na.sub.2 
SO.sub.4 and then filtered. 200 ml of C.sub.10 OXO alcohol is then added 
to the filtered solution and isobutyl alcohol and a portion of the OXO 
alcohol are removed in a revolving evaporator, at 100.degree. C., under a 
vacuum of about 1 mmHg. There is thus obtained 88.5 g of a molybdenum blue 
solution soluble in any proportion in most of the hydrocarbons, including 
crude oils or reduced crude oils. 
The molybdenum content of this alcoholic solution is 24.75% by weight. 
The resulting catalyst will be designated as catalyst A. 
The stability of the hydrocarbon solutions of catalyst A is shown by the 
following tests: 
(a) catalyst A obtained in test No. 1 is placed in a bubbling flask and 
diluted with heptane (90% by volume of heptane, 10% of catalyst A). During 
1 hour at 20.degree. C., 30 liters/hour of a mixture containing 15% by 
volume of hydrogen sulfide and 95% of hydrogen, is caused to bubble. At 
the end of this treatment, the liquid remains blue and no precipitate is 
formed. 
(b) the solution of catalyst A, in a proportion corresponding to 2 g of 
molybdenum, is diluted into 200 g of a reduced crude oil charge from 
Kuwait (Table II) and the mixture is heated up to 360.degree. C. in the 
presence of hydrogen. It is observed that the solution remains 
substantially homogeneous (in contrast with the case where the solvent is 
isopentyl alcohol). Then, if the asphaltenes are separated by heptane 
precipitation (standard NF T 07025), it is observed that the major part of 
molybdenum is to be found in the asphaltene phase. 
Test No. 2 
Test No. 1 is repeated except that 34.9 g of cobalt octoate solution in 
toluene are added to the alcoholic solution. After stirring, there is 
obtained an homogeneous solution whose molybdenum contents is 17.7% and 
cobalt content 3.11%. The resulting solution is called catalyst B. 
Test No. 3 
Test No. 2 is repeated except that nickel octoate is added, instead of 
cobalt octoate. The resulting solution contains 17.7% of molybdenum and 
3.10% of nickel; it is called catalyst C. 
Test No. 4 
The operation is conducted as in test No. 1, except that 18.8 g of cobalt 
nitrate hydrate are added to the 55.8 g of ammonium paramolybdate. The two 
salts are finely crushed before the addition of 1350 cc of distilled water 
heated to 60.degree. C. The mixture is vigorously stirred up to complete 
dissolution and then the operation is conducted as in test No. 1. There is 
thus obtained 95 g of a blue alcoholic solution having a 22.4% molybdenum 
content and a 4% cobalt content. It is called catalyst D. 
Table I below summarizes the characteristics of the prepared molybdenum 
blues. 
TABLE I 
______________________________________ 
CATALYST 
COMPOSITION A B C D 
______________________________________ 
Mo 25 17.7 17.7 22.4 
Co 0 3.11 0 4 
Ni 0 0 3.10 0 
______________________________________ 
EXAMPLE 2 
A series of tests of the catalytic properties of the obtained solutions is 
conducted. The characteristics of the charge are reported in Table II. 
TABLE II 
______________________________________ 
ORIGIN: 
reduced Kuwait crude oil, fraction boiling above 350.degree. C., 
specific gravity (g/cc at 15.degree. C.) = 0.969 
sulfur content g/100 g = 4 
total nitrogen content in ppm by weight = 2100 
metal content (Ni + V) in ppm by weight = 65 
asphaltene content, % by weight = 2.78 
S content of the asphaltenes = 7.8% 
Conradson carbon = 9.5 
resin content/isopropanol = 10.6 
sulfur content of the resins = 10.6% 
______________________________________ 
In the catalytic tests, sulfur is determined by a combustion method with an 
induction oven according to standard NF 07 025. Nitrogen is determined by 
the Kjeldahl method. The asphaltene content is determined according to 
standard NFT 60-115 (Asphaltenes to normal heptane). Nickel and vanadium 
are determined after mineralization and dissolution in aqueous phase, by 
the atomic absorption technique. The "resins/isopropanol" content is 
determined on the maltenes obtained by deasphalting with n-heptane, by 
reproducing the analysis method standard NF T 07025 with isopropanol as 
precipitation solvent. 
DESCRIPTION OF THE APATUS 
The catalytic tests are conducted in a 500 cc autoclave provided with 
external stirring means operated by rocking. The autoclave is connected to 
a pressurized hydrogen source. A special device makes it possible to 
withdraw 10 g samples for analysis during the test. The autoclave is 
provided with a regulated electric heating system; the temperature 
indicated in the description of the tests is that of the liquid medium 
during the experiment. 
OPERATING CONDITIONS OF A TEST 
A known weight of catalyst (as solution in a polar solvent) is added to 200 
g of hydrocarbon subjected to the treatment. The reactor is closed and a 
test at a pressure of 100 kg/cm.sup.2 is performed with cold hydrogen. The 
hydrogen is then purged and fresh hydrogen is fed at a pressure of 30 
kg/cm.sup.2. The temperature programmation and stirring are then started. 
After a period of 2 h 30, the reactor temperature attains the value 
preselected for the test. The pressure is then adjusted to the desired 
value by addition of fresh hydrogen and this instant is taken as initial 
time (zero time). 
Before analysis thereof, the resulting products are centrifuged for 
separating solid deposits therefrom. 
To 200 g of Kuwait reduced crude oil (see Table II) there is added a 
catalyst amount corresponding to 2 g of molydbenum. The tests are 
conducted according to the above-described operating conditions. 
The results and the operating conditions are reported again in Table III. 
TABLE III 
______________________________________ 
CHARGE: Kuwait reduced crude oil 200 g 
Catalyst amount corresponding to 2 g of molybdenum 
Pressure: 90 kg/cm.sup.2 Temperature: 370.degree. C. 
Stirring: 200 oscillations per minute 
Test duration: 6 hours at a temperature of 370.degree. C. 
S 
CON- 
TENT 
% ASPHALTENES RESIN 
CATA- by CONTENT CONTENT Ni V 
LYSTS weight % by weight % by weight 
ppm ppm 
______________________________________ 
A 2.77 0.8 3.6 5 4 
B 2.08 0.69 3.24 2 1 
C 2.08 1 2.6 8 2 
D 2.12 0.72 3.3 3 2 
______________________________________ 
It is observed that the 4 tested catalysts are active. Catalysts B and D, 
which correspond to two different ways of introducing the elements of 
group 8, have similar activities. The catalysts B and D are more active 
than the catalyst based on molybdenum alone. The catalyst C wherein nickel 
has been introduced, is active for sulfur removal to the same extent as B 
and D, less active for the hydrodestruction of asphaltenes but more active 
for removing the sulfur contained in the asphaltenes and resins which 
remain in solution after the reaction. Finally, all the catalysts A, B, C 
and D are very active for hydrodemetallization. 
EXAMPLE 3 
When using the same charge as in example 2 and catalyst B in the same 
operating conditions except the reaction temperature which is 390.degree. 
C. and then 410.degree. C., instead of 370.degree. C., the following 
results, reported in Table IV, are obtained: 
TABLE IV 
__________________________________________________________________________ 
S CONTENT 
ASPHALTENES 
RESINS TEMPERA- 
% CONTENT CONTENT 
TURE 
CATALYST 
by weight 
% by weight 
% by weight 
.degree.C. 
__________________________________________________________________________ 
B 2.08 0.69 3.24 370 
1% Mo with 
respect to 
the charge 
1.46 0.43 1.40 390 
0.8 0.25 0.55 410 
__________________________________________________________________________ 
It is clear that the temperature increase improves the catalyst 
performance. 
EXAMPLE 4 
The operating conditions are the same as in Example 2 except with respect 
to the catalyst whose amount is varied. The obtained results are reported 
in Table V. 
It is observed that all the results are satisfactory. The best results, as 
far as the main reactions of desulfurization and asphaltenes removal are 
concerned, are obtained with a catalyst content from 1 to 0.2% by weight. 
TABLE V 
__________________________________________________________________________ 
ANALYSIS OF THE HYDROCARBONS 
AFTER THE TEST 
% of Mo SULFUR ASPHALTENES 
RESINS 
INTRODUCED 
CONTENT 
CONTENT CONTENT 
CATA- 
IN THE TEST, 
% % % Ni V 
LYST by weight 
by weight 
by weight 
by weight 
ppm 
ppm 
__________________________________________________________________________ 
2% 2.5 2.5 0.08 2 1.5 
B 1% 2.08 0.69 3.24 2 1 
0.5% 1.96 0.71 6.18 3 1.5 
0.2% 2.27 1.4 4.46 3.5 
1.5 
__________________________________________________________________________ 
EXAMPLE 5 
Example 2 is repeated with the use as catalyst of a molybdenum blue 
solution of type B of example 1 in various solvents at the same 
concentrations as in example 1. 
The following Table VI reports the results obtained. 
TABLE VI 
______________________________________ 
ASPHAL- 
SULFUR TENES 
CONTENT CONTENT Ni V 
SOLVENT % by weight 
% by weight 
ppm ppm 
______________________________________ 
Ethyl sulfate 
2.25 0.72 4 3 
Tricresylphosphate 
2.19 0.85 3 2 
Benzophenone 
2.15 0.91 5 2 
Ethyl oleate 
2.22 0.88 4 2 
Anisole 2.30 0.74 5 12 
______________________________________ 
EXAMPLE 6 
Example 2 is repeated with the use as catalyst of a molybdenum blue 
solution prepared as in test No. 1 of example 1, except that sodium 
phosphate is not used. 
It has been found that the resulting product contains 2.83% by weight of 
sulfur, 1.1% by weight of asphaltenes and has a total metal content (Ni+V) 
of 11 ppm by weight. 
EXAMPLE 7 
(comparison) 
Test No. 1 of example 1 is repeated except that the addition of C.sub.10 
OXO alcohol is omitted: the molybdenum blue solution in isobutyl alcohol 
has been directly used as catalyst in example 2, except that all the 
alcohol has been evaporated before performing the hydrotreatment, so as to 
give a colloidal form to molybdenum. The molybdenum weight (2 g) was 
unchanged. 
The following results were obtained: 
______________________________________ 
Sulfur: 3.1% by weight 
Asphaltenes: 1.3% by weight 
V + Ni: 13 ppm by weight 
______________________________________ 
EXAMPLE 8 
(comparison) 
A test has been conducted in the same conditions as in example 2 with the 
use of molybdenum naphthenate of the trade, containing 6.4% of molybdenum. 
The molybdenum content (2 g) is the same as precedingly. 
The following results were obtained (by weight): 
______________________________________ 
Asphaltenes content: 1.38% 
Resins content: 6% 
Sulfur content: 2.7% 
Ni + vanadium: 20 ppm 
______________________________________ 
The comparison with the examplified catalysts prepared according to the 
invention shows that molybdenum naphthenate is less active. 
EXAMPLE 9 
In order to make apparent the performances of the catalyst for 
demetallization, a test has been performed with an equipment for 
continuous operation. The charge is a mixture containing 50% by weight of 
atmospheric gas oil and 50% by weight of 350.degree. C.sup.+ vacuum 
residue of Cabimas. The characteristics of the mixture are as follows: 
______________________________________ 
Asphaltenes: 7.25% by weight 
Resins: 13% by weight 
Ni: 36 ppm 
V: 450 ppm 
Sulfur: 2.1% by weight 
______________________________________ 
Catalyst B of example 1 is introduced into this hydrocarbon mixture in such 
an amount as to obtain a 0.2% content by weight of molybdenum in the 
mixture. This mixture is introduced into the reactor at a VVH of 0.2 
volume of mixture per volume of reactor and per hour. The temperature is 
400.degree. C., the pressure 100 bars and the hydrogen flow rate 180 
liters of hydrogen measured under normal conditions, per liter of 
hydrocarbon in the same conditions. 
The results are reported in Table VII. 
TABLE VII 
______________________________________ 
CHARACTERISTICS 
OF THE PRODUCT CONVERSION RATE IN 
(after centrifugation) 
PROPORTION OF THE 
by weight- CHARGE IN % 
______________________________________ 
Asphaltenes 
% 3.78 47.8 
Resins % 6.71 48.4 
Sulfur % 1.60 23.8 
Ni ppm 18 50.0 
V ppm 150 66.7 
______________________________________