US3169918A - Hydrorefining heavy oils using a pseudo-dry catalyst - Google Patents

Description

Feb. 16, 1965 w. K. T. GLEIM HYDROREFINING HEAVY OILS USING A PSEUDO-DRY CATALYST Filed July 2, 1962 N 1/ EN r05; Will/am K. 71 6/6/11;

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ATTORNEYS United States Patent 3,169,918 HYDROREFINHWG HEAVY OILS USING A PSEUDO-DRY CATALYST William K. T. Gleim, Island Lake, 111., assignor to Universal Gil Products Company, Des Plaines, 11].,

a corporation of Delaware Filed July 2, 1962, Ser. No. 206,919 Claims. (Cl. 208264) This invention relates to a process for upgrading heavy hydrocarbon stocks in the presence of hydrogen and a catalyst. More particularly, the present invention is directed to an improved catalytic hydrorefining process for effecting in a single operation the substantial removal of various types of impurities, as hereinafter described, from crude oil, crude residua, and heavy distillates obtained therefrom.

Crude petroleum oil, topped crude, and other heavy hydrocarbon fractions and/or distillates derived therefrom contain various nonmetallic and metallic impurities. Among the nonmetallic impurities are nitrogen, sulfur and oxygen which exist in heteroatomic compounds and are often present in relatively large quantities. Nitrogen is undesirable because it rapidly poisons various catalysts which may be employed in the conversion of petroleum fractions; in particular, nitrogen must be removed from all catalytic hydrocracking charge stocks. Nitrogen and sulfur are also objectionable because combustion of hydrocarbonaceous fuels containing these impurities releases nitrogen oxides and sulfur oxides which are noxious, corrosive and present a serious problem in the field of air pollution. Sulfur, of course, is deleterious in motor fuels because of odor, gum formation and decreased lead susceptibility.

Another class of undesirable constituents found in crude oil and residual oils are asphaltenes which are non-distillable, oil-insoluble, high molecular weight coke precursors containing sulfur, nitrogen, oxygen and metals; they are colloidally dispersed in raw crude oil but when subjected to heat, as in vacuum distillation, the asphaltenes flocculate and polymerize thereby making their conversion to more valuable oil-soluble products extremely diflicult; thus, in the heavy bottoms from a reduced crude vacuum distillation column, the polymerized asphaltenes are solid materials at ambient temperature. Such product is useful only as road asphalt or, when out back with middle distillates, as low grade fuel and commands a price substantially below that of the raw crude oil itself.

The most common metallic contaminants are nickel and vanadium, although other metals including iron, cop per and zinc are often present. These metals may occur as suspended metal oxides or sulfides or water-soluble salts which may be removed, at least in part, by filtration, water-washing, electric desalting, or other fairly simple physical means; mainly, however, the metals occur as thermally stable metallo-organic complexes such as metal porphyrins and derivatives thereof. Most of the metallo-organic complexes are linked with the asphaltenes and becomeconcentrated in residual fractions, but some of the remaining metallo-organic complexes are volatile, oil-soluble, and are therefore carried over in distillate fractions. Reducing the concentration of the metalloorganic complexes is not easily achieved, at least' to the extent that the crude oil or other heavy hydrocarbon charge stock may be made suitable for further processing. Even though the concentration of these metallo-organic complexes may be relatively small in distillateoils, for example, often less than about 10 p.p.m. as theelemental metal,.subsequent processing techniques are often adversely affected thereby. For example, when a hydrocarbon charge stock containing metallo-organic compounds, such as metal porphyrins, in excess of about 3,169,918 Patented Feb. 16, 1965 ice 3.0 p.p.m. calculated as the elemental metal, is subjected to hydrocracking or catalytic cracking for the purpose of producing lower-boiling components, the metals deposit upon the catalyst, the concentration thereof increasing with time. Since vanadium and the iron group metals favor dehydrogenation activity, at cracking temperatures, the resulting contaminated hydrocracking or cracking catalyst produces increasingly excessive amounts of coke, hydrogen and light hydrocarbon gases at the expense of more valuable liquid product until eventually the catalyst must be subjected to elaborate regeneration techniques or be replaced with fresh catalyst. The presence of excessive quantities of metallo-organic complexes adversely affects other processes including catalytic reforming, isomerization, hydrodealkylation, etc. Vanadium itself is also objectionable in heavy fuel oils and residual solids used as fuels because vanadium pentoxide formed during combustion is a strong acid at high temperature and will corrode the refractory lining, tube supports and other internal hardware of a fired heater utilizing such fuel.

The desirability of removing these impurities is obvious and well known to workers in the art. Heretofore in the field of catalytic hydrotreating, two principal approaches have been advanced: liquid phase hydrogenation and vapor phase hydrocracking. In the former type of process, the oil is passed upwardly in liquid phase and in admixture with hydrogen through a fixed bed or slurry of subdivided catalyst; although perhaps effective in removing oil-soluble metallo-organic complexes, it is relatively ineffective against oil-insoluble asphaltenes which are colloidally dispersed in the charge with the consequence that the probability of effecting simultaneous contact between catalyst particle, asphaltene molecule and hydrogen is remote, at least at space velocities which are commercially attractive. Furthermore, since the hydrogenation zone is at elevated temperature, the retention of unconverted asphaltenes suspended in a free liquid phase oil for too long a time will result in their floccula tion which makes their conversion even more diflicult. Also, the efliciency of hydrogen-to-oil contact obtainable by bubbling hydrogen through an extensive liquid body is relativelylow. Vapor phase hydrocracking is carried out with either a fixed bed or expanded bed system at temperatures at substantially above 950 F.; while it obviates to some extent the drawbacks of liquid phase hydrogenation, it is not well suited totreating crude oil and residual oil because of high coke make and resultant rapid deactivation of the catalyst which requires high capacity catalyst regeneration equipment in order to implement the process on a continuous basis; furthermore, selective cracking of a wide boiling range charge stock is not easily obtained, and excessive amounts of light gases are produced at the expense of more valuable intermediates; also, when charging crude oil, a minimum limit on cracked gasoline production is unavoidable which is not always desirable where the refiner wishes to maximize production of middle and heavy distillates such as jet fuel, diesel oils, furnace oils and gas oils.

A principal object of the present invention is to hydrorefine a heavy oil under conditions which simulate a vapor phase operation but which involve only minimal cracking which is selective toward asphaltenes, whereby to effect a very substantial reduction in the asphaltene content of the charge stock through conversion thereof to oil-soluble hydrocarbons.

Another object of the present invention is to substantially eliminate metallic contaminants present in a heavy hydrocarbon charge stock.

Another object of this invention is to lower materially the concentration of non-metallic impurities, e.g., nitrogen, sulfur and oxygen, present in a heavy oil whereby to eliminate or reduce the cost of whatever subsequent distillate treating facilities may be required.

A further object of this invention is to provide a process for upgrading heavy oils under extremely mild hydrocracking conditions which maximize middle and heavy distillate production. V p

The processof the present invention can be characterized as a mixed phase combinationhydrorefining-stripping operation employing a fluid bedof pseudo-dry hydrogenation catalyst. It has beenfound that a hydrogenation catalyst comprising a porous, refractory inorganic oxide carrier having a Well developed pore structure has the ability to sorb into itspore 'structure a substantial quantity, e.g.,.up to about 50% by weight, of high-boiling hydrocarbons while yet appearing ostensibly dry and freeflowing. Such non-agglomerated oil-bearing catalyst is designatedherein as a pseudo-dry catalyst; representative compositions and physicalcharacteristics of suitable catalytic composites are set forth more fully hereinbelow. It has further been found that converted asphaltenes that is,asphaltenes"which have been hydrorefined under mild.

hydrogenative cracldngconditions. to yield oil-soluble high-boiling hydrocarbons, comprise an excellent'solvent for untreated asphaltenes which arethemselves pentaneinsoluble and are colloidally dispersed in a crude -oil charge orjagglomeratively dispersed in a topped crude oil charge. The untreated asphaltenes are muchmore readily converted to oil-soluble product when initially dissolved in such solvent than when directly treated in a dis persed phase suspended in liquid carrier. The asphaltene solvent is sorbed into the pseudo-dry hydrogenation catalyst particlesand is preferentially retained thereby, as against lower boiling portions of the hydrotreatedcharge stock, when said particles are subjected to contact with a gaseous stripping medium. The instant invention utilizes the foregoing properties to efiect in a singly hydrotreating zone the substantial removal of asphaltenes, metals, nitrogen, oxygen and/or sulfur from heavy oils containing same.

. A broad embodiment of the present invention relates to a process for hydrorefining a heavy hydrocarbon oil which comprises'maintaining in ahydrorefining zone under hydrorefining conditionsapseudo-dry fluidized bed of absorptive hydrogenation catalyst particles, partially vaporizing said heavy oil by preheating it in the absence of catalystto a temperature below that at which any sub stantial thermal cracking thereof can occur, introducing the partiallyvaporized oil into said hydrorefining zone and contacting it inthe presence of hydrogen with'said catalyst particles, sorbing unvaporized oil into said. catalyst particles to avoid any substantial accumulation of free liquid phase oil within the hydrorefining zone, flowing a hydrogen-containing gas upwardly through said hydrorefining zone and therewith stripping hydrorefined oil from the, catalyst particles, withdrawing from said hydro- 1 refining zone vaporous eiiluent and recovering therefrom ahydrorefined product of improved purity.

Another embodiment of the present invention is directed to a process for hydrorefininga heavy hydrocarbon oil containing asphaltenes which comprises partially vaporizing the oil by preheating it to a temperature below that at which any substantial thermal cracking thereof can occur; maintaining in.a hydrorefiningzone under hydr-orefining conditions a pseudo-dry fluidized bed of absorptive hydrogenation catalyst particles having sorbed therein a liquid-phaseasphaltene :solvent comprising hydrorefined asphaltenes; introducingsaid partially vaporized oil into said hydrorefining zone 'a'nd contacting it in the presence of hydrogen with said solvent-bearing catrefining zone, and dissolvingin the particle-held solvent the asphaltenes.containedin. the embed oil; converting said dissolved asphaltenes into additional'asphaltene' sol-' 4 vent; flowing a hydrogen-containing gas upwardly through said hydrorefining zone and therewith stripping hydrorefined oil from the catalyst particles but leaving sorbed therein a portion of said asphaltene solvent; contacting the resulting" stripped solvent-bearing catalyst particles with additional incoming heavy oil; and withdrawing from said hydrorefining zone vaporous efiiuent and recovering therefrom hydrorefined oil of reduced asphaltene content.

.. ing the partially vaporized oil into said hydrorefining zone at a rate of about 0.25-20 pounds of total oil charged per pound of catalyst present in. said zone per hour and therein contacting said partially vaporized oil in the presence of hydrogen with said catalyst particles; sorbing unvaporized oil into said catalystparticles to avoid any sub stantial accumulation of free liquid phase oil'within the hydrorefining zoneg flowi'ng a heated hydrogen-containing gas upwardly through said hydrorefining zone at a rate of about 5,000300,000 standard cubic feet perbarrel of oil charged and therewith stripping hydrorefined oil from the catalyst particles; and withdrawing from said hydrorefining zone vaporous effiuent and recovering therefrom a hydrorefined product of improved purity.

Many types. of heavy hydrocarbon oils may be treated by means of this invention including full boiling range crude oil, topped or reduced crude oil, atmospheric distillates, heavy cycle oils from thermally or catalytically cracked stock, light and heavy'vacuum gas oils, etc. The instant process is particularly well adapted to hydrorefiningstoc'ks containing oil-insoluble asphaltenes such as crude oil and crude residua; ,of these, crude oil is a preferred .stock because the soil-insoluble asphaltenes being in their native environment are colloidally dispersed and thus more readily converted to oil-soluble hydrocarbons, whereas the asphaltenes in reduced crude have already been agglomerated to some extent by reason of a the reboil temperature of fractionationand are therefore less easily converted. Another obvious advantage in hydrotreating :crude oil ,in toto, rather than fractions thereof, is that subsequent separate treating steps of individual cut's may be eliminated to a considerable extent. to'upgrading distillate stocks containing oil-soluble resins and maltenes and/ or other of the above-discussed metallic and non-metallic contaminants, and may be employed, for example, as the feed preparation unit to a catalytic hydrocracking process forthe conversionof cycle oils and gas oils.

As above noted this invention broadly involves con tacting a mixed phase heavy oil .charge with hydrogen and a pseudo dry particle-form hydrogenation catalyst maintained in a fluidized state under conditions which suppress cracking in excess of the extent necessary to convert or remove impurities and which avoid accumulation of a body of liquid phase oil withinthe hydrorefining zone. Conditions of temperature and pressure within the hydrorefining zone are not particularly critical,

should be in excess of about 500 p.s.i.g. with an upper economic limit of about 5000 p.s.i.g., the preferred pressure range being about-1000,3000 p.s.i.g. Hydrorefining temperatures willrange from about 650 F. to about 950 Higher temperatures are permissible and desir-- :able :for lighter charge. stocks such as cycle oil andgas- The instantprocess is, however, also well suited oil than for heavier charge stocks. When charging total crude oil, for example, the preferred hydrorefining temperature range is about 650850 F., and in no event should the temperature here exceed about 900 F. above which excessive cracking and coke laydown on the catalyst and apparatus internals occur. Under the desired minimal cracking conditions, hydrogenation predominates over cracking to the extent that the process is slightly exothermic.

In carrying out this process it is important to minimize cracking, both thermal and catalytic, of the heavy oil charge prior to its introduction into the hydrorefining zone, while yet imparting suflicient heat thereto to vaporize its lower boiling components and bring the total charge reasonably close to hydrorefining temperature. This is accomplished by preheating the heavy oil charge, in the absence of catalyst and preferably in admixture with hydrogen, to a temperature suflicient to partly vaporize it but below the temperature at which substantial thermal cracking thereof can occur. Generally speaking, the charge should be preheated to a tempera ture within the range of about 500900 F. and preferably in the range of about 650800 F. Thermal cracking within the hydrorefining zone proper is substantially avoided by immersing the point or points of mixed phase oil introduction in a hydrogen atmosphere so that the hot incoming oil is assured of initially contacting the catalyst in the presence of hydrogen; such hydrogen atmosphere is preferably provided by introducing a hydrogen-containing gas into the hydrorefining zone below the feed introduction point and flowing both hydrogen and feed cocurrently upwardly through the fluidized catalyst bed.

Maintaining a pseudo-dry fluidized catalyst bed and preventing formation of free liquid phase oil Within the hydrorefining zone are essential elements of the present process whereby to furnish a high concentration of active catalyst sites in relation to asphaltene and metal porphyrin molecules, to avoid flocculation of asphaltenes, and to minimize cracking and coke formation which contribute to rapid catalyst deactivation and loss of liquid product. Such a system is realized by the conjunctive effect of the following factors: (1) partial vaporization of the feed stock as above described, (2) use of absorptive hydrogenation catalyst particles, (3) employing a relatively low oilacatalyst Weight ratio, and (4) employing a relatively high hydrogenzoil ratio. A stream of hydrogen-containing gas, which in a commercial process may contain up to 50% of vapors other than hydrogen is passed upwardly through the catalyst bed at a rate within the range of from about 5,000 to about 300,000 standard cubic feet of hydrogen per barrel of total oil charged, and preferably in the range of about 10,000- 200,000 standard cubic feet per barrel. This hydrogencontaining stream, herein designated as recycle hydrogen since it is conveniently recycled externally of the hydrorefining zone, fulfills a number of functions; it serves as a hydrogenating agent, a fluidizing medium, a heat carrier and a hydrocarbon stripping medium. In particular, the high recycle hydrogen rate decreases the partial pressure of the oil vapor and increases vaporization of the oil without raising it to thermal cracking temperature, and maintains the catalyst bed substantially isothermal so that no vertical temperature gradient exists. The weight hourly space velocity of the charge, specified here as the weight ratio of total oil charged to catalyst contained in the hydrorefining zone per hour is Within the range of about 0.25-20 pounds of oil per pound of catalyst per hour, and preferably in the range of about 1-5 pounds of oil per pound of catalyst per hour. When the heated mixed phase hydrocarbon charge is initially contacted with absorptive hydrogenation catalyst particles, the heavier liquid phase portion of the charge is partly sorbed into the catalyst particles and partly entrained in the upflowing hydrogen stream as fine droplets; the already vaporized portion of the charge is swept upwardly through the catalyst bed by the hydrogen stream while the lighter liquid phase portion of the charge is vaporized by contact with hot catalyst particles and hydrogen. By virtue of the combined efifects of vaporization, gas stripping and sorption by catalyst, no free liquid phase oil can form within the hydrorefining zone. The non-volatilized oil is sorbed into the catalyst particles which, however, remain dry and free flowing. This heavy fraction, which is rich in impurities, is thus exposed to a large number of active catalyst sites and is subjected to mild cracking and hydrogenation under the most favorable conditions to yield lower-boiling hydrocarbons of substantially reduced impurity content. The upflowing hydrogen stream strips off from the catalyst particles the lower-boiling hydrorefined oil as it is formed.

The efiluent from the hydrorefining zone is passed through an upper particle separation zone and is withdrawn from the upper portion thereof as a substantially catalyst-free, vaporous stream comprising hydrogen, light hydrocarbon gases, oil vapors, and which may contain some entrained liquid droplets. Hydrorefined oil is recovered from this overhead stream, while the hydrogen separated therefrom is returned to the hydrorefining zone together with outside hydrogen to replenish the net hydrogen consumption which may range from 200-2000 standard cubic feet per barrel of charge depending upon the nature of the charge.

The pseudo-dry catalyst system is especially advantageous where the heavy oil charge contains oil-insoluble asphaltenes, which are very effectively converted by the autosolvent hydrorefining mechanism inhering in this process. As previously pointed out, asphaltenes which have been hydrorefined under mild hydrogenative cracking conditions to yield oil-soluble high-boiling hydrocarbons comprise an excellent solvent for untreated asphaltenes which are themselves pentane-iusoluble and are colloidally dispersed in a crude oil charge. Through proper correlation of weight hourly space velocity and recycle hydrogen rate, not all of the hydrorefined oil is removed from the catalyst particles by hydrogen stripping, but a portion of the hydrorefined asphaltenes, which are among the highest boiling components of the hydrorefining zone efliuent, is left sorbed in the catalyst particles to act as a solvent for incoming asphaltenes and reaches an equilibrium level in a lined-out operation. The heavier liquid phase portion of the raw charge, rich in asphaltenes, is sorbed into the catalyst particles and the asphaltenes are then dissolved in the particle-held solvent thereby accelerating their conversion via selective hydrocracking to additional asphaltene solvent. Part vof the solvent is stripped from the particles by the hydrogen stream, but the remainder of the solvent is left sorbed therein to dissolve additional incoming asphaltenes. The untreated asphaltenes contained in the heavy oil charge therefore constitute a continuous source of asphaltene solvent by autogeneration in situ and preferential retention thereof by the absorptive hydrogenation catalyst particles.

Non-metallic impurities such as nitrogen, sulfur and oxygen are converted by the present process to ammonia, hydrogen sulfide and water respectively, which are removed from the hydrorefining zone together with the mixed-phase efiluent stream. Metallic impurities such as nickel, iron and vanadium are deposited upon the catalyst and gradually build up in concentration; although catalyst activity is not particularly impaired thereby under the condition utilized herein, it may be desirable to withdraw, continuously or intermittently, a small'slipstream of catalyst from the hydrorefining zone, to chemically regenerate it by any suitable means such as treating with hydrogen chloride and/ or chlorine 'to volatilize the metals, and to return the regenerated catalyst of reduced metal content to the hydrorefining zone.

The hydrogenation catalyst of the present invention can be broadly characterized as comprising a metallic component having hydrogenation activity composited with a refractory inorganic oxide carrier of synthetic or natural origin havinga medium-to-high surface area and a welldeveloped pore structure asis familiar to those skilled in the art of-hydrocarbon catalysis; The composition and method of manufacturing thecatalyst is not important to the present invention save only that it have the necessary absorbency to retain substantial .amounts of liquid phase material within its pores in order to operate as a pseudodry system. Suitable metallic components having hydrogenation activity are the metals ofGroups VB, VIB, and VIII ofthe Periodic Table, e.g., vanadium, niobium, tantalum, molybdenum, tungsten, chromium, iron, cobalt, nickel, platinum, palladium, iridium, osmium rhodium, ruthenium, and compounds thereof. The hydrogenation catalyst may comprise any one or combination of any number of such metals which may exist in the elemental state or as the oxides or sulfides thereof in varying degrees of oxidation. The catalytic concentration of the metallic component or components, stated here on the basis of the elemental metal, will depend primarily on the particularv metal involved; for example, the Group VI metals are preferably present in an amount within the range of about 1-20%' by weight, the iron group metals in an amount within the range of about 02-10%, and the platinum group metals in an amount within the range of about 0.014%. Suitable refractory inorganic oxide carriers include alumina, silica, Zirconia, magnesia,.titania, thoria, boria, strontia, hafnia and mixtures of two or more oxides such as silicaalumina, silica-zirconia, silica-magnesia, silica-titania, alumina-zirconia, alumina-magnesia, aluminatitania, magnesia-zirconia, titania-Zirconia, magnesia-titania, silica-alumina-zirconia, silica-alumina-magnesia, silica-alumina-titania, silica-magnesia zirconia, silica-magnesia-titania, etc. The carrier may compriseadditional promoters such as combined halogens, particularly fluorine or chlorine, boric acid, phosphoric acid and boron phosphate. The carrier may be formed by any of numerous techniques known to those skilled in the art such as acid-treating a natural clay,.coprecipitation or successive precipitation from hydrosols, frequently coupled with one or. more activating steps including hot oil aging,,steaming drying, oxidizing,.reducing, calcining,'etc. The pore structure of the carrier, commonly defined in terms of surfacelarea, pore diameter and'pore volume, maybe developed to within specified limits, for example, by aging the hydrosol and/ or hydrogel under. controlled acidic and/ or basic conditions at ambient or elevated temperature, by gelling the carrierat a critical pH, or by treating the carrier with various inorganic or organic reagents. The catalytically active metallic component or components may be composited. withthe carrier by. impregnating the freshly precipitated or finished carrier with a solution of a soluble metal compound or by coprecipitating the metal with the carrier from an aqueous solution thereof. A hydrogena 'tion catalyst appropriate for use in the present-invention will have a surface area of'about 50-700 square meters per gram, a pore diameter of about 20-300 A, a pore volume of about 0.10-0.80milliliter per gram, and an apparent bulk density of about.0'.200.80 gram per cubic centimeter. Measurement ofsurface area, pore diameter and porevolume of catalytic composites may be done ac- I cording to the methods set forth in Catalysis, volume I, pp. 37-40,,Reinhold PublishingCornpany (1954). The

catalyst particles themselves preferably should have diameters ranging from about 5 to about 1000 microns in order,

to functionproperly in a fluidized bed; in the case of nonspherical particles the maximum dimension of such particle should fall' within this range- Particle sizes-of this magnitude may be readily achieved by spray-drying the carrier or by grinding the catalyst in a colloid mill. By way of specific example, a very satisfactory hydrogenation catalyst comprises 2% nickel and 16% molybdenum on an equimolar alumina-silica carrier (63 Al O /37% SiO another good catalyst comprises 1% nickel and 8% molybdenum on an alumina-silica-boron phosphate carrier general preparation of which is described in US. Patent The present process may be further illustrated upon reference to the accompanying drawing which is a simplilied flow diagram embodying the principalfeatures of the invention insofar as they are capable of graphical representation. Heavy oil charge. is introduced through line 1, mixed with hydrogen from line 19, and passedthrough combined feed preheater 2 wherein about 50-75% of the hydrocarbonaceous charge is vaporized. The heated mixed phase feed is passed via transfer line 3 and toroidal feed distributor, .6 into the lower portion of vertical reactor-.4 which contains a fluidized catalyst bed 5. Heated stripping and fiuidizing hydrogen is fed'to the bottom of reactor 4- from hydrogen preheater 17 through transfer line 18. T he-hydrogen is distributed through perforated plate 7 and flows upwardly around feed distributor 6 into catalyst bed 5 wherein the sorbed oil is hydrorefined and stripped from the catalyst particles. The upper portion of the reaction vessel comprises a particle separation zone 8 of enlarged cross-sectional areawherein the-catalyst is disengaged from the mixed phase reactor efiluent. A

off through line'19 and admixed with the heavy oil chargev to suppress coking in heater 2. This proportion may range from 20% to of the total recycle hydrogen flow. It'is preferred, however, that a major proportion of the hydrogen be separately preheated in heater 17 and charged to the hydrorefining zone through line 18; in some cases, this stripping hydrogen may be heated to as much as F. above the temperature. of the combined feed inline 3, since it serves to raise the feed from preheat temperature to hydrorefining temperature which is best done in the simultaneous presence of hydrogenand catalyst to minimize thermal cracking. The stripping hydrogen is preferably heated to within the range: of about 600-1000 F.

' Various additions to and modifications of this flow scheme will be obvious to those skilled inthe art. For example, a catalyst regenerator vessel may be connected with reactor 4 such that a dragstream of catalyst is continuously or intermittantly regenerated by metal and coke removing techniques. The unit may be operated in conjunction with hydrogen production or purification facilities whereby a stream of hydrogen iscontinuously withdrawn from the. recycle system to maintain hydrogen purity ata constant level, and make-up hydrogen may be added to line 1 instead of line ,12. The hot overhead vapors in line 9 may be heat exchanged against heavy oil charge or recycle hydrogen prior. to being cooled in con.-

' denser 10. A pipe grid may be substituted for perforated plate 7. Cyclone separators, electricalprecipitators or other separation equipment may be used in lieu of, or incon uncti-on with, the enlarged area particle separation.

. EXAMPLE 'I A Wyoming sour crude oil is hydrorefined by the abovedescribed continuous process in the presence of a pseudodry catalyst comprising 2% nickel and 16% molybdenum on a porous refractory support consisting of 68% The charge 1 Al O SiO 22% BPO and having a particle size in the range of 10-150 microns. The Wyoming sour crude oil has a gravity of 22.5 API and contains 2.8% by weight of sulfur, 2700 p.p.m. of nitrogen, and 80 p.p.m. of vanadium and p.p.m. of nickel as metallo-organic complexes; in addition, this sour crude comprises 8.3% by weight of pentane-insoluble asphaltenes. The crude oil is admixed with recycle hydrogen of 90% hydrogen purity in the ratio of 17,000 standard cubic feet per barrel of total oil charged, the mixture is preheated to 700 F. and charged to the hydrorefining zone. The weight ratio of total oil charged to catalyst contained in the hydrorefining zone per hour (WHSV) is 1.5. Stripping and fluidizing hydrogen is separately preheated to 850 F. and fed to the bottom of the hydrorefining zone in the ratio of 51,000 standard cubic feet per barrel. The fluid catalyst bed itself is maintained at a temperature of 800 F. under a total pressure of 2000 ps.i.g. Net hydrogen consumption is 1000 standard cubic feet per barrel. Liquid yield on a weight basis is 95 the remaining 5% of the charge is converted to light gases as follows: 2% to C -C hydrocarbons, 1.9% to H S, 1.1% to H O. A comparison of the gravities and impurities levels of the total crude charge and liquid product is given in Table I.

Table I Liquid Product EXAMPLE II A topped Wyoming sour crude oil (90% of material boiling below 400 F. removed) is hydrorefined by the above-described continuous process in the presence of a pseudo-dry catalyst comprising 2% nickel and 16% molybdenum on a porous refractory support consisting of 63% alumina-37% silica and having a particle size in the range of 10-150 microns. The topped crude oil has a gravity of 19.5 API and contains 3% by weight of sulfur, 2850 p.p.m. of nitrogen, and 84 p.p.m. of vanadium and 21 p.p.m. of nickel as metallo-organic complexes; in addition, this topped crude comprises 8.5% by weight of pentane-insoluble asphaltenes. The topped crude oil is admixed with recycle hydrogen of 90% hydrogen purity in the ratio of 14,000 standard cubic feet per barrel of total oil charged, the mixture is preheated to 725 F. and charged to the hydrorefining zone. The weight hourly space velocity (WHSV) is 0.85. Stripping and fiuidizing hydrogen is separately preheated to 820 F. and fed to the bottom of the hydrorefining zone in the ratio of 42,000 standard cubic feet per barrel. The fluid catalyst bed itself is maintained at a temperature of 775 F. under a total pressure of 2000 p.s.i.g. Net hydrogen consumption is 1070 standard cubic feet per barrel. Liquid yield on a weight basis is 95% the remaining 5% of the charge is converted to light gases as follows: 2% to C -C hydrocarbons, 2% to H S and 1% to H O. A comparison of the gravities and impurities levels of the topped crude charge and liquid product is given in Table II:

Table II Topped Crude Charge Liquid Product It will be observed from the data given in Examples I and II that vanadium removal exceeds 99.9%, nickel removal exceeds 99.8%, and conversion of pentane-insoluble asphaltenes is in excess of 99.6%. The 31 API product recovery is by weight, which for a 22.5 API charge corresponds to a liquid volume yield of about 102%. Selective conversion of asphaltenes and metalloorganic complexes with minimum overall cracking is quite apparent in view of the high weight recovery and gravity reduction.

These beneficial results are obtained through the use of a pseudo-dry fluidized bed of absorptive catalyst particles obtained by partial feed vaporization, a high catalyst: feed ratio, and a high hydrogentfeed ratio. With respect to asphaltene conversion by autosolvent hydrorefining, the liquid phase converted asphaltenes sorbed in the catalyst particles act as an asphaltene solvent for incoming asphaltenes which upon conversion provide a continuous source of additional solvent. i

I claim as my invention:

1. A process for hydrorefining a heavy hydrocarbon oil containing asphaltenes which comprises maintaining in a hydrorefining zone under hydrorefining conditions a pseudo-dry fluidized bed of absorptive hydrogenation catalyst particles, partially vaporizing said heavy oil by preheating it in the absence of catalyst to a temperature below that at which any substantial thermal cracking thereof can occur, introducing the partially vaporized oil into said hydrorefining zone and contacting it in the presence of hydrogen with said catalyst particles at asphaltenehydrorefini'ng conditions, sorbing unvaporized oil comprising hydrorefined asphaltenes into said catalyst particles to avoid any substantial accumulation of free liquid phase oil within the hydrorefining zone, flowing a hydrogen-containing gas upwardly through said hydrorefining zone and therewith stripping hydrorefined oil from the catalyst particles, withdrawing from said hydrorefining zone vaporous efiluent and recovering therefrom a hydrorefining product of improved purity.

2. The process of claim 1 further characterized in that said heavy hydrocarbon oil is a crude oil.

3. The process of claim 1 further characterized in that said heavy hydrocarbon oil is a vacuum gas oil.

4. The process of claim 1 further characterized in that said heavy hydrocarbon oil is a heavy cycle oil.

5. The process of claim 1 further characterized in that said heavy oil is preheated in admixture with hydrogen.

6. The process of claim 1 further characterized in that said heavy oil is preheated to a temperature in the range of about 500-900 F.

7. The process of claim 1 further characterized in that said hydrorefining zone is maintained at a temperature in the range of about 650950 F. and a pressure in excess of about 500 p.s.i.g.

8. The process of claim 1 further characterized in that a major proportion of said hydrogen-containing gas is preheated separately from the heavy oil charge to a temperature in the range of about 600-1000 F. prior to its introduction into said hydrorefining zone.

9. A process for hydrorefining a heavy hydrocarbon oil containing asphaltenes which comprises maintaining in a hydrorefining zone, at a temperature in the range of about 650950 F. and a pressure in the range of about 500-5000 p.s.i.g., a pseudo-dry fluidized bed of absorptive hydrogenation catalyst particles; partially vaporizing said heavy oil by preheating it in the absence of catalyst to la temperature in the range of about 500900 F. but below that temperature at which any substantial thermal cracking thereof can occur; charging the partially vaporized oil into said hydrorefining zone at a rate of about 0.25-20 pounds of total oil charged per pound of catalyst present in said zone per hour, and therein contacting said partially vaporized oil in the presence of hydrogen with said catalyst particles at asphaltene-hydrorefining 11 conditions; sorbing unvaporized oil comprising hydrorefined asphaltenes into said catalyst particles to avoid any substantial accumulation of free liquid phase oil within the hydrorefining zone; flowing a heated hydrogen-containing gas upwardly through said hydrorefining zone at a rate of about 5,000-300,000 standard cubic feet per barrelof oil charged and therewith stripping hydrorefined oil from the catalyst particles; and with drawing from said hydrorefining zone vaporous effluent and recovering therefrom a hydrorefined product of improved purity. V

10. A process for hydrorefining a heavy hydrocarbon oil containing asphaltenes which comprises,.the steps of 2 (1) partially vaporizing the oil by. preheating it to a temperature below that at which any substantial thermal cracking thereof can occur;

(2) maintaining in a hydrorefining zone under hydrorefining conditions a':pseudo-dry fluidized bed of absorptive hydrogenation catalyst particlesv having sorbed therein a liquid-phase asphaltene solvent comprising hydrorefined asphaltenes;

(3) introducing said partially vaporized oil into said hydrorefining zone and contacting it in the presence of hydrogen with said solvent-bearing catalyst particles at asphaltene-hydrorefining conditions;

(4) sorbing unvaporized oil comprising hydrorefined 12 asphaltenes into said solvent-bearing catalyst particles whereby to avoid any substantial accumulation of free liquid phase oil within the hydrorefining zone, and dissolving in the particle-held solvent the asphaltenes contained in the sorbed oil;

(5) converting said dissolved asphaltenes into additional asphaltene solvent;

(6) flowing a hydrogen-containing gas upwardly through said hydrorefining zone and therewith stripping hydrorefined oil from the catalyst particles but leaving sorbed therein a portion of said asphaltene solvent;

(7) contacting the resulting stripped solvent-bearing catalyst particles with additional (incoming heavy oil; and

(8) withdrawing from said hydrorefining zone vaporous eflluent and rec ovening therefrom hydrorefined. oil of reduced asphaltene content.

References Cited in the file of this patent UNITED STATES PATENTS 2,914,463 Nicholson Nova 24, 1959 2,926,132 Weikart et a1. Feb. 23,1960 Osborne Feb; 12, 1963'

Claims (1)

1. A PROCESS FOR HYDROREFINING HEAVY HYDROCARBON OIL CONTAINING ASPHALTENES WHICH COMPRISES MAINTAINING IN A HYDROREFINING ZONE UNDER HYDROREFINING CONDITIONS A PSEUDO-DRY FLUIDIZED BED OF ABSORPTIVE HYDROGENATION CATALYST PARTICLES, PARTIALLY VAPORIZING SAID HEAVY OIL BY PREHEATING IT INTHE ABSENCE OF CATALYST TO A TEMPERATURE BELOW THAT AT WHICH ANY SUBSTANTIAL THERMAL CRACKING THEREOF CAN OCCUR, INTRODUCING THE PARTIALLY VAPORIZED OIL INTO SAID HYDROREFINING ZONE AND CONTACTING IT IN THE PRESENCE OF HYDROGEN WITH SSAID CATALYST PARTICLES AT ASPHALTENEHYDROREFINING CONDITIONS, SCORBING UNVAPORIZED OIL COMPRISING HYDROREFINED ASPHALTENES INTO SAID CATALYST PARTICLES TO AVOID ANY SUBSTANTIAL ACCUMULATION OF FREE LIQUID PHASE OIL WITHIN THE HYDROREFINING ZONE, FLOWING A HYDROGEN-CONTAINING GAS UPWARDLY THROUGH SAID HYDROREFINING ZONE AND THEREWITH STRIPPING HYDROREFINED OIL FROM THE CATALYST PARTICLES, WITHDRAWING FROM SAID HYDROREFINING ZONE VAPOROUS EFFLUENT AND RECOVERING THEREFROM A HYDROREFINING PRODUCT OF IMPROVED PURITY.

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