Heavy oil process with hydrodemetallation, hydrovisbreaking and hydrodesulfuration

A process for conversion of an asphaltenes-containing heavy oil or heavy oil fraction to lighter fractions comprises 3 steps of: catalytic hydrodemetallation, hydrovisbreaking and catalytic hydrodesulfuration.

BACKGROUND OF THE INVENTION 
This invention relates to the treatment of heavy oil or heavy oil fractions 
of high asphaltene content, in order to convert them to less heavy 
fractions, more easy to transport or to treat with the usual refining 
processes. Oils from coal hydrogenation may also be treated. 
More particularly, the invention solves the problem of converting a 
viscous, non transportable, crude oil of high metals, sulfur and 
asphaltenes content and comprising more than 50% of constituents having a 
normal boiling point higher than 520.degree. C., to a stable, easily 
transportable, hydrocarbon product of low metals, sulfur and asphaltenes 
contents and having only a reduced content, for example less than 20% by 
weight, of constituents of normal boiling point higher than 520.degree. C. 
The problem solved by the invention has been studied for a long time; the 
main difficulty to overcome is that of the deactivation of the catalysts 
by impurities, mainly metal impurities, from the treated charges. Thus, 
for example, a crude oil from Boscan or from Cerro Negro may contain from 
200 to 1000 ppm by weight or more of metals; these metals are mainly 
vanadium and nickel, together with variable proportions of iron and other 
metals. 
The deactivation of hydrotreatment catalysts if illustrated by U.S. Pat. 
No. 4,017,380 having for object to cope with this difficulty by using a 
cyclic process; a catalytic hydrodesulfuration (HDS) unit (I) precedes a 
visbreaking (II) unit containing a deactivated HDS catalyst; as soon as 
the active hydrodesulfuration catalyst (I) is deactivated, the operations 
are reversed after replacement of catalyst (II) by fresh catalyst: the 
charge then passes over the active HDS catalyst (II) under HDS conditions, 
then over the inactive catalyst (I) under hydrovisbreaking conditions. 
There is a need on the market for a really continuous process wherein the 
hydrotreatment catalyst may be used over several weeks or several months 
without deactivation. 
SUMMARY OF THE INVENTION 
The process of the invention comprises the essential following steps: 
(a) A first step of passing the hydrocarbon charge, admixed with hydrogen, 
over a catalyst containing alumina and at least one metal or compound of 
metal from at least one of groups V, VI and VIII (iron group), said 
catalyst being characterized in that it consists of a plurality of 
juxtaposed conglomerates, each of which is formed of a plurality of 
acicular plates, the plates of each conglomerate being generally oriented 
radially with respect to one another and with respect to the conglomerate 
center. 
(b) A second step of subjecting the product from step (a) to 
hydrovisbreaking conditions. 
(c) A third step of subjecting the product from step (b) to a treatment 
with hydrogen, in contact with a catalyst containing alumina and at least 
one metal or compound of a metal selected from the group consisting of 
molybdenum, tungsten, nickel, cobalt and iron.

DETAILED DISCUSSION 
According to a preferred embodiment, the step (c) is conducted in two 
successive stages: 
A first stage in contact with a catalyst (C.sub.1) containing alumina, at 
least one molybdenum and/or tungsten compound and at least one nickel 
and/or cobalt compound, the ratio by weight of the metals: 
##EQU1## 
being from 0.8:1 to 3:1 and preferably from 1:1 to 2:1, one of the metals 
at the numerator or at the denominator being optionally omitted; 
A second stage in contact with a catalyst (C.sub.2) containing alumina, at 
least one molybdenum and/or tungsten compound and at least one nickel 
and/or cobalt compound, the ratio by weight of the metals: 
##EQU2## 
being from 0.2:1 to 0.5:1, preferably from 0.25:1 to 0.35:1, one of the 
metals at the numerator or at the denominator being optionally omitted. 
The ratio by weight of catalyst C.sub.2 to catalyst C.sub.1 is preferably 
from 1:1 to 9:1. 
The catalyst of step (a) has been described in the allowed U.S. patent 
application Ser. No. 505,557 filed June 17, 1983 whose disclosure is 
incorporated herein by reference. The essential information is summarized 
hereinafter: 
As a general rule, a large proportion, mostly at least 50%, of the acicular 
plates have a size along their longer axis from 0.05 to 5 micrometers and 
preferably from 0.1 to 2 micrometers, a ratio of said size to their 
average width from 2 to 20 and preferably from 5 to 15, a ratio of said 
size to their average thickness from 1 to 5000 and preferably from 10 to 
200. A large proportion, often at least 50% of the acicular plates 
conglomerates form a collection of pseudo-spherical particles of an 
average size from 1 to 20 micrometers, preferably from 2 to 10 
micrometers. Such a structure is adequately represented, for example, by 
pictures of a heap of thorny chesnut-hulls or a heap of sea-urchins. 
FIG. 1 comparatively shows the pore distribution curve of a catalyst (A) as 
used in step (a) of the invention and those corresponding to monomodal (C) 
or bimodal (B) catalysts of the prior art. 
The catalyst according to the invention has preferably the following pore 
distribution: 
Total pore volume: 0.7 to 2.0 cc/g, preferably 0.90 to 1.30 cc/g. 
% of the total pore volume in pores of average diameter smaller than 10 
nanometers: 0-10. 
% of the total pore volume in pores of average diameter from 10 to 100 
nanometers: 40-90. 
% of the total pore volume in pores of average diameter from 100 to 500 
nanometers: 5-60. 
% of the total pore volume in pores of average diameter from 500 to 1000 
nanometers: 5-50. 
% of the total pore volume in pores of average diameter larger than 1000 
nanometers: 5-20. 
The specific surface of this catalyst is from 50 to 250 m.sup.2 /g and more 
preferably from 120 to 180 m.sup.2 /g. 
The scanning electron microscopy technique is an unambiguous means for 
characterizing by microphotographs a catalyst having the above structure. 
FIGS. 2 to 5 show four microphotographs with enlargements of 300 times, 
3000 times, 10 000 times and 20 000 times respectively, of a catalyst 
according to the invention (catalyst A), well illustrating the particular 
structure similar to juxtaposed sea-urchins as above mentioned. 
FIG. 6 shows a microphotograph, with a nominal enlargement of 110 000 
times, of an acicular plates beam of catalyst A, illustrating the typical 
shape of these plates. The intervals between the opposite arrows with 
reference number 1 identify the edgewise plates trace and are an 
approximate measuring value of the thickness of these plates. The interval 
between the opposite arrows indicated with reference 2 identifies a plate 
parallel to the plane of the photograph and is a measuring value of the 
average width of said plate. In FIG. 6, the scale is 9 nanometers for 1 
millimeter and the dark-colored portions correspond to the catalytic 
substance. 
On the contrary, FIGS. 7 to 10 show four microphotographs taken with the 
same respective enlargements as in FIGS. 2 to 5 and with the same 
apparatus, of a catalyst sample (catalyst B) prepared by using bimodal 
alumina balls obtained by the process patented in France under no 2 449 
474: these photographs are a good illustration of the description given in 
the latter patent, i.e. that macroporosity results from interparticle 
voids existing between spheroidal microporous particles whose granulometry 
distribution and piling compactness determine the macroporous volume and 
the macropores size. On the photographs of FIGS. 2 to 5 and 7 to 10 the 
dark-colored areas correspond to void spaces in the catalyst structures, 
i.e. to the macroporosity, whereas the pale portions correspond to the 
catalytic substance. 
The distribution of the macropores diameters of catalyst B may be measured 
on the photographs and effectively corresponds to that measured by means 
of a mercury-pump porosimeter, as shown in FIG. 1. The comparison of the 
microphotographs makes apparent that the microporous spheroidal particles 
of catalyst B do not have the sea-urchin structure as obtained for 
catalyst A used in the step (a) of the invention. 
The catalysts used in step (a) of the present process have an excellent 
resistance to clogging of the pore openings; this result may be explained 
as follows: 
The pores of these catalysts, formed in major part of void spaces located 
between the radially oriented acicular plates, are "wedge" pores, hence of 
continuously varying diameter. 
These radially oriented pores are not necessarily linear. 
These radially oriented pores are not channels giving access to micropores 
of diameter lower than 10 nanometers, as in the known catalysts, but they 
form themselves a mesoporosity resulting in a catalytically active 
surface. 
A catalyst for use in step (a) of the invention may be prepared according 
to the following method, without limiting the invention to this particular 
method of preparation: 
Conglomerates of alumina particles of a size from about 0.1 to 10 
millimeters or of powder particles of a size from about 20 to 100 
micrometers, having themselves the above-mentioned sea-urchin structure 
and having substantially the same characteristics as those of the catalyst 
of the invention, particularly as concerns the shape and the size of the 
plates and conglomerates, the specific surface and the porosity, are used 
as carrier. 
By any known method, there is deposited on these conglomerates one or more 
catalytic metals, i.e. at least one metal or compound of a metal 
pertaining at least to one of groups V, VI and VIII (iron group) of the 
periodic classification, more particularly one or more of the following 
metals: molybdenum, tungsten, iron, vanadium, cobalt and nickel. Preferred 
associations thereof are molybdenum+cobalt, molybdenum+nickel, 
vanadium+nickel, tungsten+nickel. 
The above-mentioned metals are mostly introduced as precursors such as 
oxides, acids, salts, organic complexes, in such amounts that the catalyst 
contains from 0.5 to 40% and preferably from 1 to 20% by weight of these 
metals, as oxides. These precursors are well known and hence need not be 
listed here. The final step comprises an optional drying and a thermal 
treatment at a temperature from 400.degree. to 800.degree. C. 
The alumina conglomerates may be manufactured from alumina optionally 
containing other elements, for example sodium, rare earths or silica. 
Alumina containing from 100 to 1000 ppm by weight of silica is preferred. 
The operation is preferably conducted as follows: 
(a) Alumina conglomerates are treated in an aqueous medium formed of a 
mixture of at least one acid capable to dissolve at least a portion of the 
alumina conglomerates with at least one compound supplying an anion 
capable to combine with the dissolved aluminum ions, this latter compound 
being a chemical compound different from the above-mentioned acid. 
(b) The resultant conglomerates are simultaneously or subsequently 
subjected to a treatment at a temperature from about 80.degree. C. to 
about 250.degree. C. for a period from about a few minutes to about 36 
hours. 
(c) The conglomerates are optionally dried and are subjected to thermal 
activation at a temperature from about 500.degree. C. to about 
1100.degree. C. 
The active alumina conglomerates according to the invention may be prepared 
from active alumina powder of insufficiently crystallized and/or amorphous 
structure, for example, that obtained according to the process disclosed 
in the French Pat. No. 1 438 497. 
The active alumina is generally obtained by quick dehydration of aluminum 
hydroxides such as bayerite, hydrargillite or gibbsite, nordstrandite or 
aluminum oxyhydroxides such as boehmite and diaspore. 
The active alumina agglomeration is achieved by methods well known in the 
art and particularly by pelletizing, extrusion, shaping as balls in a 
revolving bowl granulator, etc. 
Preferably this agglomeration is effected, as it is well known in the art, 
with addition of porogenous agents to the mixture to be agglomerated. The 
porogenous agents are mainly wood dust, charcoal, cellulose, starch, 
naphthalene, and more generally any organic compound liable to be removed 
by calcination. 
The conglomerates are then optionally subjected to maturation, drying 
and/or calcination. 
The resultant active alumina conglomerates generally have the following 
characteristics: their loss on heating, measured by calcination at 
1000.degree. C., is from about 1 to about 15%, their specific surface is 
from about 100 to about 350 m.sup.2 /g and their total pore volume is from 
about 0.45 to about 1.5 cc/g. 
The active alumina conglomerates are then treated in an aqueous medium 
consisting of a mixture of at least one acid for dissolving at least a 
portion of the alumina conglomerates and at least one compound supplying 
an anion able to combine with the dissolved aluminum ions. 
According to the invention, an acid able to dissolve at least a portion of 
the alumina conglomerates is any acid which, when contacted with the 
active alumina conglomerates as above defined, dissolves at least a 
portion of the aluminum ions. The acid must dissolve at least 0.5% and at 
most 15% by weight of the alumina of the conglomerates. Its concentration 
in the aqueous treatment medium must be lower than 20% by weight and 
preferably from 1% to 15%. 
Strong acids such as nitric acid, hydrochloric acid, perchloric acid, 
sulfuric acid or weak acids at such a concentration that their aqueous 
solution has a pH lower than about 4, are preferably used. 
According to the invention, a compound supplying an anion able to combine 
with dissolved aluminum ions, is any compound capable to liberate in 
solution an anion A(-n) liable to form with cations Al(3+), products 
having an atomic ratio n(A/Al) lower than or equal to 3. An illustration 
of particular compounds is given by basic salts of general formula 
Al.sub.2 (OH) xAy wherein 0&lt;x&lt;6; ny&lt;6; n representing the number of 
charges of anion A. 
The concentration of this compound in the aqueous treatment medium must be 
lower than 50% by weight and preferably from 3% to 30%. 
Preferred compounds are those able to liberate in solution anions selected 
from the group consisting of the nitrate, chloride, sulfate, perchlorate, 
chloroacetate, dichloroacetate, trichloroacetate, bromoacetate and 
dibromoacetate anions and the anions of the general formula: 
##STR1## 
wherein R is a radical selected from the group comprising H, CH.sub.3, 
C.sub.2 H.sub.5, CH.sub.3 CH.sub.2 CH.sub.2, (CH.sub.3).sub.2 CH. 
The compounds able to liberate in solution the anion A(-n) may effect this 
liberation, either directly, for example by dissociation, or indirectly, 
for example by hydrolysis. The compounds may in particular be selected 
from the group comprising: inorganic or organic acids, anhydrides, organic 
or inorganic salts, esters. Among the inorganic salts, there can be 
mentioned the alkali or alkaline-earth metal salts soluble in aqueous 
medium such as the sodium, potassium, magnesium, calcium, ammonium, 
aluminum and rare earth metal salts. 
This treatment may be effected either by dry impregnation of the 
conglomerates or by immersion of the conglomerates in an aqueous solution 
of the above-mentioned mixture of acid with the compound supplying the 
desired anion. Dry impregnation means contacting the alumina conglomerates 
with a volume of solution smaller than or equal to the total pore volume 
of the treated conglomerates. 
According to a more preferred embodiment of the invention, mixtures of 
nitric and acetic acids or of nitric and formic acids are used as aqueous 
medium. 
The resultant conglomerates are simultaneously or subsequently subjected to 
a treatment at a temperature from about 80.degree. to about 250.degree. C. 
during a period from about 5 minutes to about 36 hours. 
This hydrothermal treatment does not result in any alumina loss. 
The operation is preferably conducted at a temperature from 120.degree. to 
220.degree. C., for a period from 15 minutes to 18 hours. 
This treatment constitutes a hydrothermal treatment of the active alumina 
conglomerates which results in conversion of at least a portion thereof to 
boehmite. This hydrothermal treatment may be effected either under 
saturating vapor pressure or under steam partial pressure of at least 70% 
of the saturating vapor pressure corresponding to the treatment 
temperature. 
Without limiting the present invention to a particular theory, it may be 
assumed that the association of an acid providing for the dissolution of 
at least a portion of the alumina with an anion providing for the 
formation of the above-described products during the hydrothermal 
treatment, results in the formation of a particular boehmite, a precursor 
of the acicular plates of the invention, whose growth proceeds radially 
from crystallization germs. 
Moreover, the concentration of acid and of compound in the treatment 
mixture and the hydrothermal treatment conditions are such that no alumina 
loss occurs. The porosity increase after the treatment is hence due to the 
expansion of the conglomerates during the treatment and not to an alumina 
loss. 
The resultant conglomerates are then optionally dried at a temperature 
generally from about 100.degree. to 200.degree. C. for a sufficient time 
to remove chemically uncombined water. The conglomerates are then 
subjected to thermal activation at a temperature from about 500.degree. C. 
to about 1100.degree. C. for a period from about 15 minutes to 24 hours. 
The activation operations may be performed in several steps. Preferably 
activation is performed at a temperature from about 550.degree. C. to 
950.degree. C. 
The resultant active alumina conglomerates have the following 
characteristics: 
A packed filling density from about 0.36 to 0.75 g/cm.sup.3. 
A total pore volume (TPV) from 0.7 to about 2.0 cm.sup.3 /g. 
A distribution of the pore volumes in accordance with the pore sizes 
conforming to the above-mentioned values for the catalyst used in the 
first step of the process of the invention, with the adjustment taking 
into account the weight increase due to the metals deposition. 
A specific surface measured by the B.E.T. method from about 80 to 250 
m.sup.2 /g. 
A mechanical strength from 2 to about 20 kg, measured by the grain-to-grain 
crushing method. 
The above-mentioned process for manufacturing alumina conglomerates results 
in particular in a completely unexpected modification in the distribution 
of the pore volumes in accordance with the pore size of the untreated 
conglomerates. It makes possible in particular to increase the proportion 
of pores of a size from 10 to 100 nanometers, to reduce the proportion of 
pores of a size lower than 10 nanometers and to decrease the proportion of 
pores of a size greater than 500 nanometers while not substantially 
modifying the proportion of pores of a size from 100 to 500 nanometers. 
The resultant alumina conglomerates are optionally thermally stabilized by 
rare earths, silica or alkaline-earth metals. 
As concerns step (c) of the process, it has been specified above that the 
operation is preferably conducted with the use of two successive catalyst 
beds, referred to above as (C.sub.1) and (C.sub.2). 
The carrier of catalyst (C.sub.1) preferably consists of alumina of low 
acidity, i.e. having a neutralization heat by ammonia adsorption at 
320.degree. C. lower than 40 joules (and preferably lower than 30 joules) 
per alumina gram, under an ammonia pressure of 0.4 bars. This alumina 
carrier has a surface from 50 to 300 m.sup.2 /g and preferably from 40 to 
150 m.sup.2 /g and a pore volume generally from 0.4 to 1.3 cm.sup.3 /g. An 
example of a carrier of this type is alumina subjected to autoclaving 
under steam pressure. 
Catalyst (C.sub.2), used in the second catalyst bed; preferably comprises a 
carrier of greater acidity than catalyst carrier (C.sub.1): its acidity, 
determined as above by ammonia adsorption, is preferably higher than 30 
joules/g. Its surface is preferably from 150 to 350 m.sup.2 /g and its 
pore volume preferably from 0.4 to 1 cm.sup.3 /g. Examples of carriers 
having these characteristics are .gamma.-alumina (e.g. boehmite) or 
n-alumina (e.g. bayerite) or carriers of the alumina/magnesia or 
silica/magnesia type containing about 5 to 10% by weight of magnesia. 
The techniques for incorporating active metals (e.g. Mo, W, Ni, Co, Fe) as 
used in steps (a) and (c) of the process are conventional. These catalysts 
operate mainly in their sulfurized form; their sulfuration may be effected 
before the treatment of the charge or may result from contact with the 
charge. 
Step (a) is conducted at a temperature generally from 350.degree. to 
425.degree. C. under a pressure from 40 to 200 bars, at a hourly flow rate 
of the liquid charge from 0.2 to 2 m.sup.3 /m.sup.3 /h. The hydrogen 
proportion is usually from 300 to 3000 Nm.sup.3 /m.sup.3. 
Step (b) is conducted in the presence of hydrogen in a reaction space 
either void or containing a relatively inert material, at a temperature 
from 420.degree. to 500.degree. C. under a pressure from 40 to 200 bars, 
the residence time of the charge being about 10 s to 15 minutes and the 
hydrogen proportion usually from 300 to 3000 Nm.sup.3 /m.sup.3. 
Step (c) is conducted at 300.degree. to 425.degree. C., under a pressure 
from 30 to 200 bars, the hydrogen proportion being usually from 500 to 
3000 Nm.sup.3 /m.sup.3 and the liquid charge hourly feed rate from 0.2 to 
2 m.sup.3 /m.sup.3 /h. 
The invention is illustrated by FIG. 11. 
A mixture of asphaltic heavy oil with hydrogen is fed through line 1 to the 
catalytic hydrodemetallation reactor 2, then through line 3 to the 
hydrovisbreaking reactor 4. The effluent is fed through line 5, preferably 
in the presence of additional hydrogen supplied from line 6, to reactor 7 
containing a first catalyst bed 8 and a second catalyst bed 9. The final 
product is withdrawn from line 10. 
The charges which may be treated according to the invention are, for 
example, crude oils, vacuum residues, straight-run residues, oils from 
bituminous shales or sands or asphalts. The oils have mostly a density 
higher than d.sub.4.sup.15 =0.963, an API degree lower than 15.1, an 
asphaltene content (determined with n-heptane) higher than 5% by weight, a 
content of metals (Ni+V) higher than 200 ppm by weight and a viscosity 
higher than 50 cSt (50 mm.sup.2 /s) at 100.degree. C. 
EXAMPLE 
A Cerro Negro crude oil is treated, whose characteristics are as follows: 
EQU d.sub.4.sup.15 =1.007 
.degree.API=9 
Metals (Ni+V)=500 ppm by weight 
Asphaltenes (extracted with heptane)=10.5% by weight 
Sulphur=3.7% by weight 
% distilling above 520.degree. C.=58% by weight 
Viscosity=249 cSt (249 mm.sup.2 /s) at 100.degree. C. 
This crude oil is passed, with additional hydrogen, over a catalyst (A) 
containing, by weight: 
______________________________________ 
Al.sub.2 O.sub.3 as acicular plates conglomerates 
91.5% 
MoO.sub.3 7% 
NiO 1.5% 
______________________________________ 
FIGS. 2 to 5 show microphotographs of catalyst A taken with a scanning 
electron microscope of trade mark JEOL, Model JSM 35 CF, with respective 
enlargements of 300, 3000, 10 000 and 20 000. The scales indicated on each 
photograph make it possible to measure the sizes of observable details. 
The dark parts correspond to the porosity while the pale portions 
correspond to the catalytic substance. 
It is apparent that catalyst A has effectively a structure of the 
"sea-urchins" type corresponding to a juxtaposition of conglomerates 
having in majority an average size of 3.5 micrometers, each conglomerate 
being formed of elongate acicular plates, generally radially assembled 
with respect to the center of the conglomerates. The sizes of the acicular 
plates can be measured in particular on FIG. 6, which is a microphotograph 
taken at a nominal enlargement of 110 000 with a scanning transmission 
electron microscope (S.T.E.M. VG HB5). The dark areas correspond here to 
the catalytic substance. The scale of this microphotograph is 9 nanometers 
per millimeter. The intervals defined by the opposite arrows with 
references 1 and 2 respectively correspond to the traces of the acicular 
plates positioned perpendicular and parallel to the plane of the picture. 
The intervals 1 thus give an approximate value of the thickness of the 
plates and the interval 2 a measurement of the width of the plate, i.e. 
respectively about 2 to 4 nanometers and 60 nanometers, the plates of FIG. 
6 have a length of about 0.5 to 1 micrometer, which is in accordance with 
the lengths which can be measured on FIG. 5 where these plates are shown 
in the conglomerates. The ratio of the average length to the average width 
is hence from about 8 to 16 and the ratio of the average length to the 
average thickness is from about 120 to 480. 
FIG. 1 shows in particular the aggregate pore distribution curve of 
catalyst A. The diameter of the pores (D), expressed in nanometers, is 
plotted in abscissae and the aggregate pore volume (V), expressed in 
cm.sup.3 /g, in ordinates. It is observed that the distribution conforms 
with the definition of the invention and particularly that it does not 
comprise a well apparent intermediate inflexion point. 
The passage of the charge and hydrogen over presulfurized catalyst (A) is 
effected in the following conditions: 
______________________________________ 
Temperature 380 to 410.degree. C. 
Pressure 150 bars 
Hourly feed rate of the 
0.5 m.sup.3 /m.sup.3 /h 
liquid charge 
H.sub.2 amount 800 Nm.sup.3 /m.sup.3 of charge. 
______________________________________ 
The effluent is then subjected to step (b) of the process 
(hydrovisbreaking). The conditions are as follows: 
______________________________________ 
Pressure 150 bars 
Temperature 460.degree. C. in the furnace 
450.degree. C. in the maturation chamber 
Residence time 10 seconds in the furnace 
8 minutes in the maturation chamber 
H.sub.2 amount with respect 
800 Nm.sup.3 /m.sup.3 (from step (a)). 
to the charge 
______________________________________ 
The hydrovisbreaking effluent is fed with hydrogen to a reactor comprising 
two successive catalyst beds: 
The first bed amounts to 20% by weight of the total of the two catalysts; 
it consists of nickel and molybdenum in a ratio by weight: 
##EQU3## 
The carrier of this catalyst is alumina of low acidity having a 
neutralization heat by NH.sub.3 adsorption of 20 joules/g, a specific 
surface of 140 m.sup.2 /g and a pore volume of 0.48 cm.sup.3 /g. 
This catalyst is sold on the trade by Societe Francaise PRO-CATALYSE under 
reference LD 145. 
The second bed amounts to 80% by weight of the total catalysts; it consists 
of cobalt and molybdenum in a ratio by weight: 
##EQU4## 
Its carrier is of the .alpha.-alumina type, having a specific surface of 
210 m.sup.2 /g, its pore volume being 0.52 cm.sup.3 /g; this carrier has a 
neutralization heat by NH.sub.3 adsorption of 40 joules/g. 
This catalyst is sold on the trade by Societe Francaise PRO-CATALYSE under 
reference HR 306. 
The ratio by weight of the catalyst of the second bed to that of the first 
bed is hence 4. 
The temperature in the reactor is from 370.degree. to 400.degree. C. and 
the pressure 140 bars. The hourly feed rate of liquid charge is 0.5 
m.sup.3 /m.sup.3 /h, the hydrogen proportion with respect to the charge is 
1200 Nm.sup.3 /m.sup.3. 
The final liquid product obtained after these operations has the following 
characteristics: 
EQU d.sub.4.sup.15 =0.885 
EQU .degree.API=28.4 
Content of metals (Ni+V)&lt;10 ppm by weight 
Content of asphaltenes (extracted with heptane): 1.5% by weight 
Sulfur content: 0.3% by weight 
% distilling above 520.degree. C.=12% by weight 
Viscosity: 
2.5 cSt (2.5 mm.sup.2 /s) at 100.degree. C. 
30 cSt (30 mm.sup.2 /s) at 20.degree. C. 
Yield by weight of liquid effluent with respect to the original crude oil: 
94%. 
The process has thus resulted in the conversion of a heavy, viscous, 
nontransportable crude oil of high impurity content, to a stable, easily 
transportable, synthetic crude oil of low impurity content. The life time 
of the catalysts is exceptional in view of the nature of the charge. The 
test has been discontinued after 2300 hours and at that time the activity 
of the catalyst of step (a) was still 50% of the initial activity. The 
retention capacity of this catalyst is also exceptional (130 g of metals 
retained for 100 g of fresh catalyst).