Hydrorefining an asphaltene- containing black oil with unsupported vanadium catalyst

Desulfurization and hydrorefining of an asphaltene-containing black oil with hydrogen in contact with a colloidally dispersed vanadium catalyst in admixture with 2 weight percent to 30 weight percent water biased on the weight of the oil.

APPLICABILITY OF INVENTION 
The invention described herein is adaptable to a process for the 
desulfurization of petroleum crude oil. More specifically, the present 
invention is directed toward a process for effecting a reduction in the 
sulfur content of atmospheric tower bottoms products, vacuum tower bottoms 
products, crude oil residuum, topped crude oils, the crude oils extracted 
from tar sands, all of which are sometimes referred to as "black oils," 
and which contain a significant quantity of asphaltenic material. 
Petroleum crude oils, particularly heavy oils, extracted from tar sands, 
and topped or reduced crudes, contain high molecular weight sulfurous 
compounds in exceedingly large quantities. In addition, such crude, or 
black oils contain excessive quantities of nitrogenous compounds, high 
molecular weight organo-metallic complexes consisting principally of 
nickel and vanadium, and asphaltenic material. The latter is generally 
found to be complexed, or linked with sulfur and, to a certain extent, 
with the organo-metallic contaminants. The utilization of these highly 
contaminated black oils, as a source of more valuable liquid hydrocarbon 
products, is precluded unless the sulfur and asphaltene content is sharply 
reduced, and such a reduction is not easily achieved by preferred 
techniques involving fixed-bed catalytic processing. 
The process encompassed by the present invention is particularly directed 
toward the catalytic desulfurization of petroleum crude oils utilizing a 
colloidally dispersed vanadium catalyst while simultaneously converting 
asphaltenic material. More specifically, the present invention is directed 
toward a process for hydrorefining petroleum crude oil and other heavy 
hydrocarbon charge stocks to effect the removal of nitrogen and sulfur 
therefrom, and affords unexpected advantages in effecting the destructive 
removal of organo-metallic contaminants and/or the conversion of 
pentane-insoluble hydrocarbonaceous material. 
Petroleum crude oil, and the heavier hydrocarbon fractions and/or 
distillates obtained therefrom, particularly heavy vacuum gas oils and 
topped crudes, generally contain nitrogenous and sulfurous compounds in 
large quantities. In addition, petroleum crude oils contain detrimentally 
excessive quantities of organo-metallic contaminants which exert 
deleterious effects upon the catalyst utilized in various processes to 
which the crude oil, topped crude oil, or heavy hydrocarbon fraction 
thereof may be ultimately subjected. The more common of such metallic 
contaminants are nickel and vanadium, often existing in concentrations in 
excess of about 50 ppm, although other metals including iron, copper, 
etc., may be present. These metals may exist within the petroleum crude 
oil in a variety of forms: they may exist as metal oxides or as sulfides, 
introduced into the crude oil as a form of metallic scale; they may be 
present in the form of soluble salts of such metals; usually, however, 
they are present in the form of organo-metallic compounds such as metal 
porphyrins and various derivatives thereof. Although metallic 
contaminants, existing as oxide or sulfide scale, may be removed, at least 
in part, by a relatively simple filtering technique, and the water-soluble 
salts are at least in part removable by washing and a subsequent 
dehydration procedure, a much more severe treatment is required to effect 
the destructive removal of the organo-metallic compounds, particularly to 
the degree which is necessary to produce a crude oil or heavy hydrocarbon 
fraction suitable for further processing. 
In addition to organo-metallic contaminants, including metal porphyrins, 
crude oils contain greater quantities of sulfurous and nitrogenous 
compounds than are generally found in lighter hydrocarbon fractions such 
as gasoline, kerosene, light gas oil, etc. For example, a Wyoming sour 
crude having a gravity of 23.2, .degree. API at 60.degree. F., contains 
about 2.8% by weight of sulfur and approximately 2700 ppm of total 
nitrogen, 18 ppm of nickel and 81 ppm of vanadium calculated as the 
elements thereof. Upon being subjected to a catalytic hydrorefining 
process, the nitrogenous and sulfurous compounds are converted into 
hydrocarbons, ammonia and hydrogen sulfide. However, the reduction in the 
concentration of the organo-metallic contaminants is not easily achieved, 
and they remain to the extent that they exert a detrimental effect with 
respect to further processing of the crude oil. Notwithstanding that the 
total concentration of these metallic contaminants may be relatively 
small, for example, less than about 10 ppm of metal porphyrins, calculated 
as the elemental metals, subsequent processing techniques will be 
adversely affected thereby. Thus, when a hydrocarbon charge stock 
containing metals in excess of about 3 ppm, is subjected to a cracking 
process for the purpose of producing lower-boiling components, metals 
become deposited upon the catalyst employed, steadily increasing in 
quantity until such time as the composition of the catalytic composite is 
changed to the extent that undesirable results are obtained. That is to 
say, the composition of the cracking catalyst is closely controlled with 
respect to the nature of the charge stock being processed and to the 
desired product quality and quantity. This composition is changed 
considerably as a result of the deposition of the metallic contaminants 
thereupon, the changed composite inherently resulting in changed catalytic 
characteristics. Such an effect is undesirable since the deposition of 
metallic contaminants upon the catalyst results in a lesser quantity of 
valuable liquid hydrocarbon product, and in large amounts of hydrogen and 
coke, the latter also producing relatively rapid catalyst deactivation. 
In addition to the foregoing described contaminating influences, crude oils 
and other heavier hydrocarbon fractions contain excessive quantities of 
pentane-insoluble material. For example, the Wyoming sour crude described 
above consists of about 8.3% by weight of pentane-insoluble resins and 
asphaltenes; these are hydrocarbonaceous componds considered to be coke 
precursors having the tendency to become immediately deposited within the 
reaction zone and onto the catalytic composite in the form of a high 
molecular weight, gummy residue. Since this constitutes a relatively large 
loss of charge stock, it is economically desirable to convert such resins 
and asphaltenes into useful hydrocarbon oil fractions, thereby increasing 
the liquid yield of desired product, based upon the quantity of oil 
charged to the process. 
PRIOR ART 
In U.S. Pat. No. 3,501,396, the patentee desulfurizes an 
asphaltene-containing black oil admixed with water utilizing a catalyst 
comprising nickel-molybdenum metals supported on an alumina-silica carrier 
material. The broadest teaching of metal components suitable for the 
process of U.S. Pat. No. 3,501,396 is metals selected from Group VI-B and 
VIII of the Periodic Table, as indicated in the Periodic Chart of the 
Elements, Fisher Scientific Co. (1953). Patentee further teaches the 
necessity of a catalyst support which provides a catalytic acid function, 
for example, silica. 
The patentees in U.S. Pat. No. 3,252,895 have disclosed a process for 
hydrorefining crude oil utilizing a colloidally suspended vanadium 
catalyst. 
The patentees in U.S. Pat. No. 3,303,126 have disclosed a process for 
hydrorefining crude oil in the presence of H.sub.2 and H.sub.2 S. 
The patents delineated hereinabove fail to teach a process for 
hydrorefining an asphaltene-containing black oil which comprises admixing 
black oil with water and reacting the resulting mixture with hydrogen in 
the presence of hydrogen sulfide and in contact with a colloidally 
dispersed vanadium catalyst. 
OBJECTS AND EMBODIMENTS 
The principal object of this invention is to provide an economically 
feasible catalytic crude oil desulfurization, demetallation and 
hydroconversion process in which the catalytic composite exhibits an 
unusually excellent degree of stability. The present process produces a 
crude oil product containing less than about 60 weight percent of the 
sulfur originally present in the crude oil, and simultaneously decreases 
the asphaltenic and metals content significantly. 
Therefore in a broad embodiment, the present invention encompasses a 
process for hydrorefining an asphaltene-containing black oil which 
comprises admixing said black oil with from about 2 percent to about 20 
percent by weight of water, and reacting the resulting mixture with 
hydrogen in contact with a colloidally dispersed vanadium catalyst at 
hydrorefining conditions. 
A more specific embodiment relates to a process for hydrorefining an 
asphaltene-containing black oil which comprises admixing said black oil 
with from about 2 percent to about 20 percent by weight of water, and 
reacting the resulting mixture with hydrogen in contact with a colloidally 
dispersed vanadium catalyst at a temperature within the range of about 
225.degree. C. to about 500.degree. C. and at a pressure of about 500 to 
about 5000 psig.

SUMMARY OF THE INVENTION 
The term "hydrorefining" as employed herein, connotes the catalytic 
treatment, in an atmosphere of hydrogen, of a hydrocarbon fraction for the 
purpose of eliminating and/or reducing the concentrations of various 
contaminating influences such as metals, asphaltenes, sulfur and nitrogen. 
In a fixed bed process, metals are removed by the deposition of the metals 
onto the catalyst employed. This shields the catalytically active surfaces 
from the material being processed and thereby generally precludes the 
efficient utilization of a fixed-bed catalyst system for processing such 
contaminated oil. Various moving-bed processes, employing catalytically 
active metals deposited upon a carrier material consisting of silica 
and/or alumina, for example, or other refractory inorganic oxide material, 
are extremely erosive, causing plant maintenance to become difficult and 
expensive. The present invention utilizes a colloidally dispersed, 
unsupported catalytic material which will not cause extensive erosion or 
corrosion of the reaction system. The present process yields a liquid 
hydrocarbon product which is more suitable for further processing without 
experiencing the difficulties otherwise resulting from the presence of the 
foregoing contaminants. The process of the present invention is 
particularly advantageous for effecting the conversion of the 
organo-metallic contaminants without significant product yield loss, while 
simultaneously converting pentane-insoluble material into pentane-soluble 
liquid hydrocarbons. 
A suitable unsupported vanadium catalyst is decomposed vanadyl 
acetylacetonate. Other organovanadium compounds may also be used as a 
vanadium catalyst or vanadium catalyst precursors. A preferred method for 
preparing the colloidal vanadium catalyst involves dissolving vanadyl 
acetylacetonate in an appropriate solvent such as an alcohol, ketone or 
ester containing up to and including about 10 carbon atoms per molecule. 
The solution is then added to the hydrocarbon feed stock and the mixture 
is heated at a temperature less than about 310.degree. C. to remove the 
solvent and decompose the vanadyl acetylacetonate, thereby creating a 
colloidally dispersed catalyst suspended in hydrocarbon feed stock. The 
decomposition of the vanadium catalytic precursor, in this instance 
vanadyl acetylacetonate, is effected below a temperature of about 
310.degree. C. to prevent premature cracking of the hydrocarbon, 
particularly in the absence of hydrogen. The quantity of vanadyl 
acetylacetonate is such that the colloidal suspension or dispersion, 
resulting when the material is decomposed, comprises from about 1% to 
about 10% by weight, calculated, however, as elemental vanadium. 
Typical of the alcohols suitable for use in preparing the solution of 
vanadyl acetylacetonate, include isopropyl alcohol, isopentyl alcohol, 
methyl alcohol, amyl alcohol, mixtures thereof, etc. 
The resulting colloidal dispersion is then passed together with from about 
2% to about 20% by weight of water into a suitable reaction zone 
maintained at a temperature within the range of from about 225.degree. C. 
to about 500.degree. C. and under a hydrogen pressure within the range of 
about 500 to about 5000 psig. The process may be conducted as a batch type 
procedure or in an enclosed vessel through which the colloidal suspension 
and water is passed. When the process is effected in a continuous manner, 
the process may be conducted in either upward flow or downward flow. The 
normally liquid hydrocarbons are separated from the total reaction zone 
effluent by any suitable means, for example, through the use of a 
centrifuge or settling tanks, at least a portion of the resulting 
catalyst-containing sludge being combined with the fresh hydrocarbon feed, 
and recycled to the reaction zone. In order to maintain the highest 
possible degree of activity, it is preferred that at least a portion of 
the catalyst containing sludge be removed from the process prior to 
combining the remainder with fresh hydrocarbon feed. The precise quantity 
of the catalyst containing a sludge removed from the process will be 
dependent upon the desired degree of catalytic activity. In hydrocarbon 
feed stocks containing relative high quantities of indigenous vanadium, 
new suspended vanadium catalyst is formed during the processing of the 
hydrocarbon feed in the reaction zone. In some cases this vanadium 
catalyst formation is sufficient to maintain an adequate supply of active 
catalyst for the process and in which case further addition of vanadium or 
vanadium precursors is not required. However, in other cases it may be 
desirable to add a quantity of fresh vanadium or vanadium precursors to 
the hydrocarbon charge in order to compensate for that quantity of 
vanadium removed from the process with the discarded sludge. 
The colloidal dispersion of decomposed vanadyl acetylacetonate, or other 
organovanadium compound such as the vanadyl ester of isoamyl alcohol, the 
ester of t-butyl alcohol, etc., and the hydrocarbon feed stock is reacted 
with hydrogen under hydrocarbon conversion conditions, and preferably in 
the presence of hydrogen sulfide. The catalytic material is capable of 
hydrogenating and/or hydrocracking, the more easily reduced sulfur 
compounds within the crude oil, thereby producing hydrogen sulfide. 
However, when the reactions are initiated in the presence of added 
hydrogen sulfide, a more active catalyst is produced immediately and which 
catalyst is capable of the destructive removal of the less easily reduced 
hydrocarbon contaminants. The beneficial effects of the added hydrogen 
sulfide appear to occur only when the latter is present at the time the 
hydrogenation reactions are being initiated. The hydrogen sulfide is 
generally added to the hydrogen atmosphere in an amount of about 1 to 
about 15 mol percent. 
I have discovered that if water is admixed with the hydrocarbon feed stock 
prior to the hydrogenation processing, the operating conditions for a 
given level of hydrocarbon conversion are significantly less severe than 
those currently deemed necessary. The presence of water in the process of 
my invention reduces the quantity of hydrogen sulfide which must be 
supplied to the prior art processes as well as reducing the amount of 
hydrogen circulation, and the reaction zone temperature and pressure. 
Although the hydrogenation process produces hydrogen sulfide, the 
maximization of the processes' advantages may require the presence of more 
hydrogen sulfide than can be internally generated. The production, storage 
and addition of external hydrogen sulfide is an onerous task and 
therefore, if the quantity of supplemental hydrogen sulfide is minimized, 
the advantages of a vanadium slurry catalyzed process are enhanced. 
The following examples are given to further illustrate the process of the 
present invention and to indicate the benefits to be afforded through the 
utilization thereof. It is understood that these examples are given for 
the sole purpose of illustrating methods for the practice of the present 
invention and that the examples are not intended to limit the generally 
broad scope and spirit of the appended claims. 
The crude oil employed in a Wyoming sour crude having a gravity of 
23.2.degree. API at 60.degree. F., containing about 2.8% by weight of 
sulfur, approximately 2700 ppm of nitrogen, 18 ppm of nickel and 81 ppm of 
vanadium as metal porphyrins, computed as the elemental metals. In 
addition, the sour crude consisted of about 8.3% by weight of 
pentane-insoluble asphaltenes. As hereinafter indicated, the process of 
the present invention not only effects the conversion of a significant 
proportion of the pentane-insoluble asphaltenes, but also results in a 
substantial production of lower-boiling hydrocarbons as indicated by an 
increase in gravity of the normally liquid hydrocarbon portion of the 
total product effluent. 
EXAMPLE I 
Vanadyl acetylacetonate, in an amount of 42 grams, was added to 500 grams 
of normal and amyl alcohol, and heated over a steam bath to dissolve the 
vanadyl acetylacetonate. The solution was added to 250 grams of Wyoming 
sour crude, distilling off the amyl alcohol as the same was added. Upon 
complete addition, the temperature was raised to 180.degree. C. for a 
period of 30 minutes, and 100 grams of the resulting mixture was placed in 
an autoclave and pressured to 100 atmospheres of hydrogen. After a period 
of 8 hours at a temperature of 400.degree. C. and a resulting final 
pressure of 205 atmospheres, the normally liquid portion of the product 
effluent indicated a gravity of 38.5.degree. API at 60.degree. F., and was 
contaminated by the presence of 942 ppm nitrogen, 0.4 percent by weight 
sulfur, 0.64 weight percent pentane-insoluble asphaltenes, 0.1 ppm nickel 
and 63 ppm vanadium. This example illustrates the inadequacy of vanadyl 
acetylacetonate to function as a suitable hydrorefining catalyst when 
admixed with the petroleum crude oil and subjected to hydrorefining 
conditions in the absence of added hydrogen sulfide or water. 
Notwithstanding that there has been effected a partial cleanup of the 
crude oil, the same is obviously not suitable for further processing 
without additional hydrorefining pretreatment. 
EXAMPLE II 
Sufficient vanadyl acetylacetonate was added to 125 grams of the Wyoming 
sour crude in alcohol solution to result in a colloidal suspension 
containing 2.9 weight percent vanadium. The mixture was intimately admixed 
at a temperature of 250.degree. C. for a period of 1 hour, cooled and then 
placed in the rocker-type autoclave, and initially pressured to 10 
atmospheres with hydrogen sulfide then to 100 atmospheres with hydrogen. 
The autoclave was heated to a temperature of 400.degree. C., resulting in 
a pressure of 201 atmospheres. After a period of 8 hours, the normally 
liquid portion of the total product effluent had a gravity of 37.5.degree. 
API at 60.degree. F., contained 61 ppm nitrogen, 0.01 weight percent 
sulfur, less than 0.03 ppm nickel and only 0.07 ppm vanadium, with no 
indication of the presence of pentane-insoluble asphaltenes. This example 
indicates the improved results when the vanadyl acetylacetonate is 
dispersed as an alcohol solution within the hydrocarbon oil, and hydrogen 
sulfide is added prior to initiating the hydrogenating-hydrocracking 
reactions. The utilization of the vanadyl acetylacetonate together with a 
high level of added hydrogen sulfide results in a liquid hydrocarbon 
product suitable for further processing. During the processing of the 
Wyoming sour crude with a colloidal suspension of approximately 3 weight 
percent vanadium in a continuous mode, as opposed to a batch operation, 
the inherent generation of hydrogen sulfide during sulfur removal from 
hydrocarbons will be insufficient to maximize catalytic activity, and 
therefore, additional hydrogen sulfide injection from an external source 
is highly desirable. 
EXAMPLE III 
Sufficient vanadyl acetylacetonate is added to 125 grams of Wyoming sour 
crude in alcohol solution to result in a colloidal suspension containing 
2.9 weight percent vanadium. The mixture is intimately admixed at a 
temperature of 250.degree. C. for a period of 1 hour, cooled and then 
placed in the rocker-type autoclave with 10 grams of water, and initially 
pressured to 5 atmospheres with hydrogen sulfide, then to 100 atmospheres 
with hydrogen. The pressured autoclave is heated to a temperature of 
390.degree. C., resulting in a pressure of approximately 200 atmospheres. 
After a period of 7 hours, the normally liquid portion of the total 
product effluent has a gravity of approximately 37.degree. API at 
60.degree. F., contains approximately 60 ppm nitrogen, 0.01 weight percent 
sulfur, less than 0.03 ppm nickel and 0.07 ppm vanadium, with no 
indication of the presence of pentane-insoluble asphaltenes. This example 
illustrates that when the vanadyl acetylacetonate is dispersed as an 
alcohol solution within the hydrocarbon oil and water is present during 
the hydrogenating-hydrocracking reactions, the severity of the reaction 
conditions are reduced and the requirement for the injection of additional 
hydrogen sulfide is substantially reduced.