BE601873A - - Google Patents

Description

       

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The present invention relates to a process for the conversion of hydrocarbons containing nitrogen to hydrocarbon products with a lower boiling point, and more particularly to a process for the production of hydrocarbons having a boiling point between the limits of the points. gasoline boiling point, starting from hydrocarbons with a much higher boiling point than gasoline and which are contaminated with appreciable quantities of nitrogen compounds.



   Hydrocracking which is often referred to as
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 also under the name -hy.lroE: enc: t, destructive ion "

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 to distinguish it from the simple addition of hydrogen to the ncn-saturated bonds between carbon atoms, performs well-defined changes in the molecular structure of the treated hydrocarbons. Therefore, hydrocracking can be considered retort being cracking carried out under hydrogenation conditions such that the products of lower boiling point cracking reactions are substantially more saturated than when hydrogen, or a substance providing l hydrogen is not present.

   The processes
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 r¯3hv (nnrns7tl: .tcfa are most often used for the conversion of various coals, tars and heavy waste oils in order to produce appreciable quantities of saturated products at boiling point, intermediate products suitable for their use. as household fuels, and heavier gas oil fractions which are used as household fuel, and heavier gas oil fractions which find their use as suitable lubricants.



  Although many of these hydrocracking reactions can be carried out on a thermal basis, the preferred technique of treatment involves the use of a catalyst mixture having a high degree of hydrocracking activity. However, in virtually all hydrocracking processes, whether thermal or catalytic, controlled or selective cracking is desirable from the standpoint of producing a larger amount of liquid product having improved anti-knock characteristics. and to ensure effective catalytic action for a longer period of time.

   in general, the lower molecular weight hyarocarbons which boil at
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 il = mperatiare between the li. from eb 1. tum-perature between ..., LI -1.tion of de

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 gasoline, have higher octane numbers, and a lower average molecular weight hydrocracked product will therefore generally last a higher octane number.



   Selective hydrocracking is of particular importance when processing hydrocarbons or mixtures of hydrocarbons which boil at a temperature exceeding the boiling temperatures of gasoline and middle distillates, i.e. Hydrocarbons and mixtures of hydrocarbons having an initial boiling point of between about 343 C and about 371 C, and an extreme boiling point of 538 C or higher.

   Selective hydrocracking of such hydrocarbon fractions results in higher yields of hydrocarbons having a boiling point including those of gasoline and middle distillates; that is to say, below about 343 C up to about 371 C, as well as appreciably higher yields of petroleum hydrocarbons, that is to say of hydrocarbons whose point boiling range is from about 38 C to about 204 C or 232 C, and containing isobutane and normal butane.

   Hydrocracking processes must be
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 selective in order to avoid excessive decomposition to hydro- .7 carbides of 1 = gasoline. qt. normally liquid in normally gaseous hydrocarbons, <i & Ô7 because otherwise the yield of gasoline produced may be reduced to a value at which the process is no longer economical. The desired selective hydrocracking involves the cleavage of a higher boiling hydrocarbon molecule into two molecules, both of which are normally liquid hydrocarbons.



  Also, in the selective hydrocracking, the removal of the methyl, ethyl and propyl groups which in the presence of hydrogen are converted into so-called "light paraffinic" hydrocarbons, in particular methane, ethane and propane, is controlled.

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 such that preferably no more than one of these radicals, or possibly two of them, are removed from a given molecule. For example, in the presence of hydrogen, normal decane could be reduced to two molecules of pentane, normal heptane could be reduced to hexane, and nonane to octane or heptane. On the other hand, uncontrolled or non-selective hydrocracking will result in the decomposition of normally liquid hydrocarbons into normally gaseous hydrocarbons, such as for example the conversion of normal heptane to seven molecules of methane.



   Another disadvantage of nonselective hydrocracking is the faster formation of coke and other heavy carbonaceous materials which precipitate on the catalyst and decrease its activity for the desired reactions thus shortening the process cycle and necessitating regeneration. more frequent of. catalyst, or its faster replacement with fresh catalyst. Deactivation of the catalyst also appears to inhibit hydrogenating activity to such an extent that an appreciable proportion of the hydrocarbon fraction with a boiling point close to that of gasoline, consists of unsaturated hydrocarbons, and thus this fraction does not. not very suitable for direct processing by catalytic reforming.

   Selective hydrocracking does not tend to effect appreciable hydrogenation, or saturation, of aromatics which have a high mixing octane number, and are therefore very advantageously used to increase the anti-detonating characteristics of the boiling fractions. close to that of gasoline.



   Compounds containing nitrogen contained by

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 raw material subjected to hydrocracking, such as pyrroles, amines, indoles, and other classes of organic nitrogen compounds result in relatively rapid deactivation of catalytically active metal components acting as hydrogenating agents, as well as the solid support acting as the acidic hydrocracking component of a wide variety of hydrocracking catalysts. Such deactivation appears to result from the reaction of nitrogen compounds with the various catalytic components, the value of this deactivation increasing as the treatment continues and as the nitrogenous raw material continues to contaminate the catalyst by the formation of nitrogen complexes. and catalyst components.

   Such deactivation is not a simple reversible phenomenon, since it cannot be rectified by simply heating the catalyst in the presence of hydrogen in order to decompose these nitrogenous complexes.



   The main object of the present invention is to provide a hydrocracking process which appreciably increases the yield of hydrocarbons having a boiling point close to that of gasoline, and to obtain an effectively controlled hydrocracking while avoiding the drawbacks ordinarily occurring. due to nitrogenous ontaminants and uncontrolled cracking.



   The process for the catalytic hydrocracking of hydrocarbons according to the present invention comprises reacting a stream of a hydrocarbon oil feed which boils predominantly above 204 C and containing nitrogen compounds, in a first reaction zone with hydrogen in the presence of a catalyst insensitive to nitrogen with formation of ammonia starting from, 3 said nitrogen compounds, removal of ammonia from the effluent

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 of the first reaction zone,

   then separating this effluent from a normally liquid light fraction having an extreme boiling point of between 204 C and 232 C and also separating out of said effluent from a heavier fraction containing constituents of the effluent which boiling between the final boiling temperature of said light fraction and 343 C, reacting a stream of said heavier fraction in a second reaction zone with hydrogen in the presence of a catalyst of hydrocracking sensitive to nitrogen, and Mixing at least the normally liquid portion of the effluent from said second reaction zone with the normally liquid portion of the effluent from the first reaction zone before separation from said light fraction of this effluent.



   In a specific embodiment of the invention, the mixture of the total normally liquid components of the effluents from the first reaction zone and from the second reaction zone is separated into a first fraction having an extreme boiling point of between 204 C and 232 C, a second fraction having an extreme boiling point of between 343 C and 371 C and a third fraction containing the hydrocarbons of the said mixture, the boiling point of which is higher than that of the second fraction, one reacts a stream of the second fraction with hydrogen in the second reaction zone, and at least a part of the third fraction is subjected together with the stream of the hydrocarbon feedstock to the reaction with hydrogen in the first zone of reaction.

   In this embodiment, part of the third fraction can be mixed, if desired, with the stream of the second fraction passing through the second reaction zone.

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   The nitrogen-insensitive catalyst employed in the first reaction zone preferably contains between 0.4% and 45.0% by weight of molybdenum and between 0.2% and 10.0% by weight of nickel on a consistent support. at least largely in alumina, the amount of nickel being smaller than the amount of molybdenum in the catalyst, and the support advantageously containing up to 12% by weight of silica. The nitrogen-sensitive catalyst employed in the second reaction zone generally comprises a single metal component selected from metals of Groups VI-A and VIII of the Periodic Table or mixtures of these metals on a support which in itself constitutes a cracking catalyst.

   This nitrogen-sensitive catalyst preferably contains between 0.5 and 10% by weight of nickel, or between 0.1 and 5.0% by weight of a platinum group metal on a support consisting of 88 and 75. % by weight of silica and from 12 to 25% by weight of alumina.



   In carrying out the process according to the present invention, it is preferred that the first or the second reaction zone is maintained at a pressure of between about 68 and about 204 atmospheres and that the first reaction zone is maintained at a temperature of substantially between 206 C and 538 C, while the second reaction zone is maintained at a temperature substantially between the limits of 260 C and 510 C and preferably at one. temperature 28 C to 83 C lower than the temperature in the first reaction zone.



   The present method can be understood more clearly by referring to the attached schematic drawing, which shows one embodiment.



   In this drawing, the various flow valves, chiller control valves, condensers, overhead reflux condensers, pumps, compressors, knockout pots and various accessories have been omitted because they are not.

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      essential for a full understanding of the present process and their use in the present operation will immediately be recognized by those familiar with the art of petroleum processing. t
Referring now to the drawing, the hydrocarbon feedstock, contaminated with an appreciable amount of nitrogen compounds, for example about 1000 up to about 5000 parts by weight per million parts, (ppm;

  ), and sulfur compounds up to 3.0% by weight, enter the treatment process through line 1 in line 3 where it is mixed with the hydrogen which enters through line 2. Although the hydrocarbon feedstock may have boiling points ranging from an initial boiling point of 343 C to a final boiling point of 538 C and above, the hydrocarbon feed in Line 1 should not be considered to be restricted to a feed having these boiling points.

   Therefore, the hydrocarbon feedstock forming the raw material may consist entirely of a heavy vacuum gas oil, or recycle material, having the stated limits for the boiling point, or the raw hydrocarbon material may consist of a fraction of kerosene partially boiling between the boiling points of gasoline and to a large extent between the boiling point limits of the middle distillates, i.e. a hydrocarbon feed with boiling point limits between about 177 C and about 288 C or 316 C.



  The term "middle distillate" and "light gas oil" refers to those hydrocarbon fractions which have a final boiling point of between about 343 C and about 371 C. The raw material may be a recycle light oil at the point of boiling completely between

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 the limits of the middle distillate, or else it could be a gas oil obtained under vacuum at a boiling point of between approximately 316 C and approximately 510 C. The process according to the present invention is particularly adaptable to the treatment of hydrocarbons contaminated by nitrogen having a boiling point substantially completely in excess of the boiling point of the middle distillate.



   In any case, the mixture of hydrogen and heavy hydrocarbons in the line 3, which enters the heater 4, is such that the hydrogen is present in quantities between about 178 and about 1425 normal liters per liter of charge. liquid hydrocarbon. The mixture is raised to a temperature of between about 260 C and about 5380C in the heater 4 and passes through line 5 into the cleaning reactor 6. This reactor is maintained under an imposed pressure of between about 6.8 atmospheres and about 204 atmospheres. atmospheres and according to one embodiment contains a nitrogen insensitive catalyst containing at least about 4.0% by weight molybdenum calculated as an element.

   The hydrocarbon feedstock will come into contact with the particular catalyst employed at a liquid hourly space velocity (defined as volumes of liquid feedstock per hour and per volume of catalyst in the reaction zone), between the limits of between about 0.5 and in. - about 10.0. Under these conditions, and in the presence of the molybdenum-containing catalyst, the organically bound nitrogen compounds are separated at nitrogen-hydrogen bonds to form ammonia which is released in free form from the reaction media.

   In addition, any sulfur compounds, for example mercaptans and thiophenes, are converted to hydrogen sulfides and the corresponding sulfur-free hydrocarbons. In addition to this efficient cleaning of the hydrocarbon feedstock, an appreciable conversion occurs

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 hydrocarbons, whereby heavier hydrocarbons boiling between about 371 C and about 538 C are converted by very selective cracking reactions to hydrocarbons boiling below about 371 C. The conversion reactions are such that a very small amount, or even none at all, of straight chain light paraffinic hydrocarbons occurs.

   The total reactor effluent is removed from reactor 6 by tank 7 and introduced into separator 8.



   Although shown as a single container, the separation device illustrated by separator 8 may consist of any means suitable for the separation of normally liquid hydrocarbons, which are indicated in the drawing as being removed from separator 8. through line 10, from a separate gas phase which may contain, for example, light paraffinic hydrocarbons, ammonia, hydrogen sulfide and carbon dioxide and which in the drawing is shown as leaving separator 8 through line 9.

   For example, water can be injected into line 7, being mixed there with the total effluent from the reactor and will then be subjected to separation, so that the ammonia is adsorbed and removed in the aqueous phase, while hydrogen sulfide and light paraffinic hydrocarbons are removed in gas phase, and normally liquid hydrocarbons are recovered separately through Line 10.



   The normally liquid hydrocarbons in line 10 are mixed with the effluent from hydrocracking reactor 26 or at least with the total amount of the normally liquid constituents of this effluent, retort described below, in line 11 and pass together into the fractionator 12.

   This device 12

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 operates under all appropriate pressure and / or temperature conditions resulting in the removal of light paraffinic hydrocarbons (C1 and C3) through line 13, heavier, normally liquid hydrocarbons including butanes, being removed from the fractionation apparatus 12 via line 14 in the fractionation apparatus 15 with side inlet. The device
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 Fractionation 15 contains a central well lb below which the hydrocarbons enter through line 14.



  The fractionator 15 operates under conditions of temperature and pressure such that hydrocarbons with a boiling point close to that of gasoline, including butanes, are removed through line 17, closing less than 1.0. ppm. of the aforementioned nitrogen compounds. Hydrocarbons with a boiling point close to those of the middle distillate, containing less than 5.0 ppm. nitrogen, are removed through line 21 at a point above central well 16. Any residual nitrogen compound entering fractionation apparatus 15 through line 14 is removed with the hydrocarbons boiling above it. from approximately 343 C to 371 C via line 18.

   It has been found that residual nitrogen compounds are in a wide
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 measure contained in the heavy fraction entering er:.? bulliicn at a temperature above the boiling point of the middle distillate. Hydrocarbons with a boiling point close to that of the middle distillate in line 21 exit, at least in part, introduced into line 24, containing valve 25, in heater 29.

   This stream of hydrocarbons at a boiling point close to that of the middle cistillate can be mixed with the heavier hydrocarbons coming from
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 l '; r8il Je frctiGnne, .en 15 par las c & ltic lE it -.'-- t- Cô j-I'd-i.OyirtC..cj'lt - par -t-33 Cane - Il.Ct. ttj.C'TlG
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 .- 'jj = ô is also mixed with the hydrogen ui enters through the :. - ':: ", :: cc> = - i.3ct - ::. i0n 31. If it is laughed at, a part is hy.rccnrburet

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 à Joint., t ébul, ition le ce Him du,! ist.illé: 1.t means, can be removed for storage through line 22 containing valve 23.



   In all cases where the concentration of residual nitrogen compounds of the heavier hydrocarbons leaving the
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 c.; :::: i3o.t, ion 13 is greater than about 5.0 parts per million, it is not desired to subject them to the conversion in the hydrocracking reactor 20, and in this case these hydrocarbons are preferably removed from line 18 in line 3 through valve 19 to combine with the initial hydrocarbon feedstock in line 1 and with hydrogen in line 2. In the latter method, the hydrocarbons which come to a boil at a temperature exceeding about 343 C or 371 G can be put back into the process, until exhausted.



   In any case, the hydrogen which enters through line 31 and combines with the hydrocarbons in line 24 is present in an amount of between about 178 and about 1070 normal liters per liter of these liquid hydrocarbons. The resulting mixture enters reheater 29 where it is raised to the desired temperature between about 260 ° C and about 510 ° C and generally at least 28 ° C lower than the temperature of the total feed passing through line 5 in reactor 6. The heated mixture coming from the heater 29 passes through the line 30 into the hydrocracking reactor 26.

   This reaction zone is maintained under an imposed pressure of between about 6.8 atmospheres and about 204 atmospheres and contains a suitable hydrocracking catalyst which differs from the catalyst in reaction zone 6 in being nitrogen sensitive. and contains at least one metallic component selected from metals of Groups VI-A and VIII of the Periodic Table and mixtures of these metals. The hydrocarbon feed '

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 passes from heater 29 through line 30 into hydrocracking reactor 26 at a liquid hourly space velocity of between about 1.0 and about 15.0.



   It is preferable that the total effluent coming from the hydrocracking reactor 26 passes through the line 27 containing the pump 28, into the line 11 and is then mixed with the normally liquid hydrocarbons in the line 10, then passing through the line 11 in the fractionator 12. If however desired, the normally gaseous constituents may first be separated from the effluent from the hydrocracking reactor 26 as described below, and in such case at least the constituents Normally liquid effluent from a hydrocracking reactor 26 passes through line 11.



   From the above description of the embodiment illustrated in the accompanying drawing, it can easily be seen that the present process is in fact a two-phase process for the production of hydrocarbons having a boiling point close to that of. gasoline, possessing in itself flexibility for the purpose of producing larger quantities of hydrocarbons with a boiling point close to that of the middle distillate. Various modifications can be made to the illustrated embodiment without departing from the present invention.

   For example, the separation means included in the separator 8 can be combined with the fractionation apparatus 12 and from this material one can obtain a type
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 somewhat different flow apparatus and flow apparatus. tel - k- 1wi tr However, it is obvious that a / type of flow will simply achieve the same object as that resulting from the type of flow already indicated. An essential characteristic feature of the method according to the present invention involves the system -

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 two-phase reactor, in which the liquid effluent streams from each individual phase or reaction zone are combined and then subjected to separation in the fractionator 12 and in the side-tap fractionator 15.

   The first phase using the cleaning reactor 6 achieves a practically complete destruction of nitrogen compounds as well as sulfur compounds contained in the raw material, completely or at least largely in hydrocarbons with a boiling point higher than that of gasoline. . By the appropriate choice of both the catalyst and the operating conditions, an appreciable degree of conversion will be achieved in reactor 6 by which the heavier hydrocarbons, in particular those which boil above 371 C, are converted into point-d hydrocarbons. lower boiling, without producing appreciable amounts of light paraffinic hydrocarbons, methane, ethane and propane.

   Since the catalyst in the reactor is chosen for the lack of sensitivity to nitrogen, the rapid deactivation of such a catalyst, otherwise occurring during hydrocracking of such nitrogenous feedstock, does not occur. not.



   The process according to the present invention applies most advantageously to raw materials derived from petroleum, more particularly to materials generally considered to be heavier than the fractions of average istülat. Such materials include gasoline fractions, heavy vacuum gas oils, lubricating oils and white oils, as well as high boiling bottoms or bottoms recovered from various catalytic cracking operations.

   Therefore, although the raw material of the present process may have an initial boiling point of between about 204 C and about 252 C and a

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 extreme boiling point of about 538 C or higher, the process provides additional advantages when treating raw hydrocarbon materials having appreciably higher initial boiling points, i.e. between about 343 C and about 371 C.



   In further describing the process according to the present invention and the various limitations imposed on this process, the entire process will be divided into two distinct, separate phases for the sake of simplicity and clarity. The first phase comprises a suitable reaction zone, a separation zone and / or a fractionation apparatus and these are used in such a manner and under conditions such that the practically complete removal of nitrogen and sulfur compounds from the hydrocarbon raw material, while producing hydrocarbons with a boiling point close to that of gasoline as a separate product,

   and hydrocarbons with a boiling point close to the middle distillate serving to provide most of the feed in the second phase of the entire process. Heavy hydrocarbon feed contaminated with nitrogen compounds after mixing with hydrogen and heating at the desired operating temperature is contacted with the nitrogen insensitive catalyst in the first reaction zone, the precise operating conditions of that zone depending on the various physical and chemical characteristics of the particular hydrocarbon feed that is subjected to the treatment. In any case, the reactor will be maintained at a temperature substantially between 260 C and 538 C, and under an imposed pressure generally between 6.8 atmospheres and 204 atmospheres.

   High pressures between these limits appear to promote the destructive removal of nitrogenous compounds, as well as the conversion of hydrocarbons which boil at a temperature in excess of about

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 371 C and are therefore preferable; thus, the first reaction zone is preferably operated under an imposed pressure of between about 68 atmospheres and about 204 atmospheres.

   While the hydrocarbon feedstock will contact the particular catalyst employed at a liquid hourly space velocity generally between about 0.5 and about 10.0, lower liquid hourly space velocity limits will be employed, i.e. say between about 0.5 and about 3.0 in all cases where the heavy hydrocarbon feed is contaminated with relatively large amounts of nitrogen compounds.

   The catalyst placed in this first reaction zone serves a dual function; that is, the catalyst is insensitive to the presence of appreciable amounts of both nitrogen compounds and sulfur compounds and at the same time it is capable of effecting both their destructive removal and the conversion of the entering hydrocarbons. boiling at a temperature in excess of about 343 C or 371 C. A catalyst comprising relatively large amounts of molybdenum calculated as an element, in admixture with a suitable support such as alumina, is very suitable for carrying out the desired operation in this first phase of the reaction.



  A particularly preferable catalyst mixture for use in this first reaction zone comprises between about 4.0% and about 45.0% by weight molybdenum and uses alumina as a support material. It is preferred to use alumina in the absence of other refractory inorganic oxidized materials such as silica, zirconium oxide, magnesia, titanium oxide, thorium oxide and oxide.
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 boron. , 1loiq, ue these refractory inorganic oxides can 1 "ire employed in q ': anities 2'2.LCtlv-'f: aht lawbles with respect to the' 4U '> = it.ité à'é" lqr;

  1inf and preferably more than about 12p

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 by weight of the mixture with Illumine, they appear in some cases to impart an excessive cracking activity to the catalyst in the first reaction zone such that these hydrocarbons, entering a boiling temperature at a temperature above about 343 C or 371 C, would be subjected to a non-selective cracking with production of an excessive amount of light paraffinic hydrocarbons. Small amounts of nickel, especially between about 0.2% and about 10.0%, or similar amounts of cobalt and / or iron, may be used in combination with the relatively larger amounts of molybdate.



   The catalyst mixture for use in the first reaction zone can be made in any suitable manner; a particularly suitable method.
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 # ntag6uôe uses an impregnation technique, so when the catalyst must contain both nickel and molybdenum, the preparation method involves the first formation of an aqueous solution of water-soluble compounds of the desired metals, for example nickel nitrate or nickel carbonate, and ammonium molybdate or molybdic acid. The alumina particles serving as a carrier are mixed with the aqueous solutions and are then dried at a temperature of about 93 C.

   The dry mixture is then oxidized in an oxidizing atmosphere such as air, at an elevated temperature of between about 593 C and about 927 C and for a period of between about 2 hours and about 8 hours, or more.



   Gaseous ammonia and hydrogen sulfide, resulting from the destructive removal of nitrogen and sulfur compounds in the first phase of the reaction, are removed in any suitable manner from the total reaction zone effluent. For example, the total effluent can be mixed

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 with water and then subjected to a separation such that the ammonia is absorbed in the aqueous phase. Or the total effluent from the reaction zone can be passed into a separation zone against the current with a liquid absorbent such that ammonia, hydrogen sulfide and other gaseous constituents are effectively removed.



  In addition to the removal of hydrogen sulfide and ammonia, it is desired that the small amount of light paraffinic hydrocarbons, methane, ethane and propane, resulting from the rather severe conditions prevailing in the first reaction zone, be removed from efflaent. Therefore, the separation zone can include a low temperature glow temperature so as to remove ammonia and light paraffinic hydrocarbons as a gas phase.



  As shown in the drawing, these light paraffinic hydrocarbons, together with the normally liquid hydrocarbons, can be introduced into a fractionation column so as to remove the light paraffinic hydrocarbons from the system. This latter method has the additional advantage of To be flexible enough to function as a beginner or depentanizer when desired, apply such a treatment technique. In addition, this method allows the simultaneous fractionation of the effluent from the hydrocracking reactor 26 to remove the light paraffinic hydrocarbons, after removal of the ammonia, from the effluent of the first phase of the process.



   Regardless of the particular means of separation employed, the resulting normally liquid hydrocarbons which now boil between about 38 C and about 371 C or higher, and containing butanes, will contain some residual nitrogen compounds. Normally liquid hydrocarbons are therefore distilled

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 by the use of a side-setting fractionator under conditions delivering a core fraction boiling between about 204 C and about 343 C, this core fraction being substantially entirely free of nitrogen compounds.

   Hydrocarbons which boil below about 204 C qt which include hydrocarbons with a boiling point close to that of gasoline, produced in the second phase of the process, are removed at the top of the fractionator at side socket, and can be forwarded to storage meanwhile; their subsequent use, either as feed for a catalytic reforming unit, or as a constituent of gasoline mixture. The small amount of residual nitrogen compounds is removed in the hydrocarbon fraction boiling above about 340 ° C at the bottom of the side-tap fractionator.



   The second phase of the present process is intended to convert the hydrocarbons having a boiling point close to that of the middle distillate and which are now free of nitrogen, at the same time if desired with at least part of the hydrocarbon stream entering the boiling point. above about 343 C and about 371 C, in hydrocarbons which boil between the boiling limits of gasoline.

   While it has been said above that the raw material with a boiling point close to that of the middle distillate for the second phase reaction zone 26 contains less than about 5.0 parts of nitrogen compounds per million, it It is preferred that the fractionation system be operated under conditions resulting in a hydrocarbon mixture having a boiling point near that of the middle distillate T containing less than about one part nitrogen per million, and more preferably still less than 0.3 about part nitrogen per million.

   In any case, when the hydrocarbons entering

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 boiling above a temperature between about 340 C and 371 C contain a sufficient amount of residual nitrogen compounds to cause, when fed to: The second phase of the reaction, a total concentration of nitrogen entering the the hydrocracking reactor 26 above 5.0 parts per million, these hydrocarbons will be put back into circuit through value 19 and line 3 to combine with the initial hydrocarbon feed in order to remove the excess of compounds nitrogenous.

   In such a situation, in order to maintain substantially continuous operation in hydrocracking reactor 26, a larger amount of middle distillate will be treated in this reaction zone.



   Since the total charge of hydrocarbons in the second reaction zone can contain up to about 5.0 parts nitrogen per million, it is very advantageous to use certain catalyst components which are most effective for careful hydrocracking of the middle distillate feed, containing these residual nitrogen compounds but not adversely affected by them. For example, alumina is a good agent for the removal of nitrogen when it contains relatively small amounts of silica (about 12% by weight).

   Similarly, silica is a good hydrocracking catalyst when it contains a relatively small amount of alumina, but yet it is not by itself a good agent.
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 for removal, .dé. nitrogen .. - Dunēfê8 .similaire, the metallic constituents of the catalyst placed inside the second reaction zone will show similar tendencies. For example, as well as

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 shown with respect to the first reaction zone, molybdenum is a good agent for nitrogen removal but is not relatively active as a hydrocracking or hydrogenation catalyst. On the other hand, nickel is a good hydrogenation catalyst, but does not have a relatively high degree of activity by itself for the removal of nitrogen compounds.

   Catalytic mixtures which include at least one metallic component selected from Groups VI-A and VIII of the Periodic Table including chromium, molybdenum, tungsten, iron, cobalt, nickel, palladium, platinum, ruthenium, rhodium, osmium, iridium, and mixtures of two or more of these metals, including nickel-molybdenum, nickel-chromium, molybdenum-platinum, cobalt-nickel-molybdenum, molybdenum-palladium, chromium-platinum, chromium-palladium and molybdenum-nickel, - palladium, and a mixture of silica and approximately 10% to 90% by weight of alumina, constitute hydrocracking catalysts which can be used in the second phase of the process according to the present invention,

   having a relatively high activity relative to the conversion of hydrocarbons having a boiling point close to that of the middle distillate, this activity being practically unaffected, even by the relatively small quantities of nitrogen, of less than about. 5.0 parts nitrogen per million.



   The solid support material produced synthetically for use in the secondary phase catalyst, which support material also has hydrocracking tendencies, can be obtained in any way.
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 . : ili ".". "'\ -' '... 1 ....).;.,. ,,:",:' ::: appropriate, including Its successive separate methods

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 or co-precipitation. For example, alumina can be prepared by adding a reagent such as ammonium hydroxide or ammonium carbonate to an aluminum salt, such as aluminum chloride, aluminum nitrate, or aluminum acetate, in sufficient amounts to form aluminum hydroxide. Aluminum chloride is generally preferred as the aluminum salt to be employed,

   not only for the ease of subsequent washing and filtering, but also because it seems to give better results. The resulting precipitate is converted by drying to alumina. The alumina particles can take any desired shape, such as spheres, pills or extrudates.

   A particularly preferable form of alumina is the sphere, and these spheres can be manufactured continuously by passing droplets of an alumina hydrosol through an oil bath maintained at elevated temperature, retaining the droplets in the oil bath until they solidify as solid hydrogel spheroids;

   this particular method known generally as the oil drop method has been described in detail in U.S. Patent No. 2,620,314 issued to James Hoekstra. It is understood that -The foregoing description regarding the preparation of alumina particles, star, applies to the preparation of -The support material employed in the manufacture of the catalyst mixture used in the first reaction zone. In an analogous manner, the silica can be prepared in any suitable manner, one of these methods consisting in mixing the sodium silicate and a mineral acid under conditions allowing the precipitation of a nydrogel.

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 silica.

   The silica is then washed with the water containing a small amount of suitable electrolyte in order to remove the sodium ions. Other refractory oxidized compounds can be prepared in a manner analogous to that described above by
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 return to the alvmine.



   The cracking catalyst component of the catalyst of the second reaction phase of the present process comprises at least two refractory inorganic oxides and such a mixture can be prepared in any suitable manner, including separate, sequential, or alternate methods.
 EMI23.3
 of co-precipitation. In the separate method of precipitation, the oxides are precipitated separately and are then mixed, preferably in the wet state.

   When successive precipitation methods are employed, the first oxide is precipitated as described above and the slurry moist, either with prior washing or without washing.
 EMI23.4
 preaedbîe, is mixed with a salt of the other constituent. Precipitation of the oxide of the latter component is accomplished by adding a suitable alkaline or acidic material to the resulting slurry. The resulting mixture can then be dried and shaped into the desired shape, and / or desired dimensions.

   When the catalyst employed in the second reaction pone comprises silica and alumina, and / or silica, alumina and zirconium oxide, it will be obtained by mixing an acid.
 EMI23.5
 such as hydrochloric or sulfuric acid, with silicate ....... Commercial sodium glycoside under conditions allowing precipitation of the silide, by washing the precipitate with acidulated water or by other means of removing sodium ions,

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 by mixing with an aluminum salt, such as aluminum chloride and / or any suitable zirconium salt,

   and either by then adding a bank precipitant such as ammonium hydroxide to precipitate the alumina therein, and the zirconium oxide, or by forming the oxide (s) by thermal decomposition of the salt according to the circumstances. The silica-alumina-zirconium oxide cracking component can be formed by adding together or separately the aluminum and / or zirconium salts. Other cracking components can be prepared in a similar manner.



   The catalytically active metal component of the catalyst placed in the second reaction zone is then mixed with the cracking component mentioned above. The active metal components are generally employed in amounts from about 0.1 to about 20.0% by weight of the total catalyst, and can be incorporated in any suitable manner into the cracking component.

   Impregnation techniques can be advantageously employed by first forming an aqueous solution of a water soluble compound of the desired metal, eg platinum chloride, palladium chloride, nickel nitrate, molybdate. ammonium, molybdic acid, chloroplatinic acid, or chloropalladic acid, and mixing the solution with the cracking component in a steam dryer. Other suitable metal-containing solutions which may be employed are colloidal solutions or suspensions of the desired metal cyanides, metal hydroxides or metal sulfides. When these solutions are not soluble in water at temperature

 <Desc / Clms Page number 25>

 employed, other suitable solvents such as alcohols or ethers may be employed.

   The final catalytic mixture after all of the catalytic components are present therein, is dried for a period of between about 2 hours and about 8 hours or more, and is then oxidized in an oxidizing atmosphere, e.g. air, at elevated temperature, between about 593 C and about 927 0, and for a period of between about 1 hour and about 8 hours, or more. After this high temperature oxidation, the catalyst is reduced for a period of between about half an hour and about 1 hour at a temperature between about 371 C and about 53 ° C, and in the presence of hydrogen.

   When desired, the catalyst can be reduced "in situ", that is, by placing the catalyst within the second reaction zone and subjecting it to a forced flow of hydrogen from the system. at a temperature of about, 31600.



   As described above, it is preferable that the catalyst in the second reaction zone comprises at least two refractory inorganic oxides, preferably alumina and silica. When silica and alumina are used in combination, the latter compound will generally be present in amounts of between about 10% and about 90% by weight. As shown in the examples which follow, excellent results have been obtained by the use of mixtures of 88% by weight of silica, and 12% by weight of alumina, and of 75% by weight of silica and 25% by weight of alumina, in the catalyst of the second reaction phase, thus than by using a mixture of 88% by weight of alumina, and 12% by weight of silica

 <Desc / Clms Page number 26>

 in the catalyst of the first reaction phase.

   While the total amount of metal components of the catalyst placed in the second reaction zone is between about 0.1% and about 20.0% by weight of the total catalyst, the group VI-A metal, such as chromium, molybdenum or tungsten is generally present in amounts of between about 0.5% and about 10.0% by weight of this catalyst.



  When a metal from the iron subgroup of group VIII, such as iron, cobalt or nickel, is employed in this catalyst, it is present in an amount of between about 0.2% and about 10.0%. by weight, while if a noble metal such as for example platinum, palladium or iridium is employed, it will be present in amounts of between about 0.1% and about 5.0% and preferably between 0, 1% and 2.0% by weight of the total catalyst. When the metal component of the second phase catalyst consists of both a Group VI-A metal and a Group VIII metal, it will contain metals of the above group in a weight ratio of between about 0.05: 1 and about 5.0: 1 of the metal component of Group VIII, relative to the metal component VI-A.

   Examples of metallic components in catalysts particularly suitable for use in the second reaction zone are as follows: 6.0 wt% nickel and 0.2 wt% molybdenum; 6.0% by weight of nickel; 0.4% by weight of palladium; 6.0 wt% nickel and, 2 wt% palladium; 6.0 wt% nickel and 0.2 wt% platinum.



   The catalyst employed in the second phase of the process according to the present invention is preferably placed in the reaction zone in the form of a fixed bed.

 <Desc / Clms Page number 27>

 



  Due to the characteristics of the feed in the second phase of the reaction, the operating operations in the reaction zone are relatively smooth. Therefore, the operating temperature at which the catalyst is maintained in the second reaction zone, can be at least about 28 G lower than the temperature employed in the first reaction zone. It is not uncommon in the process according to the present invention to carry out the second reaction zone at a temperature which is up to 83 ° C. lower than the temperature in the first reaction zone.

   In addition, due to the nature of the feed in the second reaction zone, the level of liquid feed in this zone can be appreciably greater than that of the feed in the first reaction zone and ordinarily it is between about 1 .0 and about 15.0 liquid hourly space velocity. The total influent from the second reaction zone can pass to a separation zone at suitable low temperature and high pressure where a gas stream rich in hydrogen is withdrawn and recirculated to provide at least part of the hydrogen which is. mixed with the liquid hydrocarbon material constituting the feed.

   The normally liquid hydrocarbons, containing the light paraffinic hydrocarbons (CI to C3) and the butanes, are combined with the normally liquid hydrocarbons resulting from the separation means employed in the first reaction phase to subsequently remove therefrom the hydrocarbons having a boiling point. close to that of gasoline.

 <Desc / Clms Page number 28>

 



   An essential characteristic feature of the present invention is the system of two separate integrated phases in which the entire process is carried out. By using the process according to the present invention, a greater concentration of hydrocarbons is produced. boiling close to that of gasoline and middle distillate starting from the hydrocarbons which come to boiling above the boiling point of the middle distillate. In addition, greater concentrations of near-boiling point hydrocarbons in gasoline are produced from hydrocarbons near boiling point of the middle distillate which were produced in the first phase of the process. .



  The total effect is an appreciable reduction in the amount of light paraffinic hydrocarbons which otherwise result from non-selective one-phase hydrocracking, with hydrocarbons boiling at a temperature above the boiling points of gasoline. Another advantage is that the use of the present invention results in retention of aromatic hydrocarbons which boil at temperatures close to the boiling points of gasoline and are suitable as constituents of engine fuel blends.

   In addition, the process according to the present invention results in a hydrocarbon product with a boiling point close to that of gasoline, substantially free of unsaturated hydrocarbons, and therefore suitable as a raw material for a unit of gasoline. catalytic re-formation in order to further raise its octane number.

   Thus, by using the process according to the present invention, a hydrocarbon feed with a boiling point exceeding approximately

 <Desc / Clms Page number 29>

 340 to 371 C can be converted almost completely into hydrocarbons with a boiling point close to that of gasoline, in spite of the presence of extremely large quantities of nitrogenous compounds and without the usual high loss of yield. of an excessive amount of light paraffinic hydrocarbons, and also without undermining the deactivation of the catalyst / encountered in the single phase hydrocracking process, oils which are generally used as raw materials in the process.



   When the present process is carried out in a continuous manner, it is preferable to use each catalyst as a fixed bed in the respective reaction zone, as illustrated in the accompanying drawings. The mixtures of hydrocarbons and hydrogen are continuously charged into the reaction zones and flow
 EMI29.1
 the downward direction through the catalyst, or if C4 e) the mixture ,, p, wc'r as desired / may flow either in an updraft or in a radial flow through the zones of readtion
 EMI29.2
 Alternatively, the operation can be done as a moving bed type, or as a suspension type of operation, where the catalyst and the hydrocarbons form a slurry through the respective reaction zone.



   The following examples are given to further illustrate the process according to the present invention and
 EMI29.3
 to indicate the advantages obtained by sor) itilization. .. -. * "" "'' '" -

 <Desc / Clms Page number 30>

 EXAMPLE I.



   This example illustrates the process according to the present invention as applied to a hydrocarbon feed, fully boiling above the boiling point of gasoline and almost completely above the boiling point of the middle distillate. . The feed was gas oil obtained under vacuum from a Wyoming-West Texas crude product and had the properties shown in Table I below, where the distillation data was determined by the ASTM method.



   Table I.



   Vacuum Diesel - Properties.
 EMI30.1
 
<tb>



  Specific <SEP> weight <SEP> to <SEP> 15.6 C <SEP> 0.9393
<tb>
<tb>
<tb> Distillation <SEP> in <SEP> CI
<tb>
<tb>
<tb>
<tb>
<tb> Initial <SEP> boiling point <SEP> <SEP> 310
<tb>
<tb>
<tb>
<tb> the% <SEP> 383
<tb>
<tb>
<tb>
<tb> 30% <SEP> 421
<tb>
<tb>
<tb>
<tb>
<tb> 50% <SEP> 446
<tb>
<tb>
<tb>
<tb> 70% <SEP> 467
<tb>
<tb>
<tb>
<tb>
<tb> 90% <SEP> 493
<tb>
<tb>
<tb>
<tb> 95% <SEP> 532
<tb>
<tb>
<tb>
<tb>% <SEP> to <SEP> 204 C <SEP> 0
<tb>
<tb>
<tb>
<tb>
<tb>% <SEP> "Bottoms" <SEP> 2.5
<tb>
<tb>
<tb>
<tb> Total nitrogen <SEP>, <SEP> ppm. <SEP> 1300
<tb>
<tb>
<tb>
<tb>
<tb> Sulfur, <SEP> weight <SEP>% <SEP> 2.58
<tb>
 
The catalyst employed in the first reaction zone comprised 2.0 wt% nickel and 22.5 wt% molybdenum calculated as element.

   the catalyst was prepared using a single impregnation technique involving 100 parts of alumina spheres (prepared by the oil drop method described in issued U.S. Patent 2,620,314

 <Desc / Clms Page number 31>

 to James Hoekstra) and a single impregnation solution containing hexahydrate nickel nitrate (2.4 parts by weight of nickel) and molybdic acid (30.0 parts by weight of molybdenum).



  The catalyst was placed in a reaction zone maintained under an imposed pressure of 102 atmospheres, and an inlet temperature in this zone of 410 C. The liquid feed was treated at a rate of 0.5 liquid hourly space velocity, and was combined with hydrogen in an amount of 1068 normal liters per liter of oil charge. Following separation to remove ammonia, hydrogen sulfide and paraffinic hydrocarbons. Lightweight (C1 to C30, the normally liquid effluent from the reaction zone was fractionated in a multi-tray distillation column to give four fractions.

   These fractions were: 1) a butane fraction at 82 ° C; 2) a fraction between 82 C and 204 C; 3) a fraction (middle distillate) between 204 C and 343 C; and 4) a bottoms fraction containing the hydrocarbons boiling at a temperature in excess of, 343 * 0. As to the amount of residual nitrogen compounds contained in these fractions, reference will again be made to the accompanying drawing. The normally liquid total hydrocarbon effluent, after the separation carried out to remove ammonia and light paraffinic hydrocarbons, i.e. the stream shown in the drawing as passing through Line 14, contained approximately 18 parts of nitrogen total per million.

   Following fractionation in the side-setting column 15, the total nitrogen content of hydrocarbons with a boiling point close to that of gasoline, those having an extreme point of about 2040, was practically zero, that of gasoline. mixed distillate fraction shown on line 21 of the drawing, contained less than 3.0 parts nitrogen per million, while the hydrocarbon stream

 <Desc / Clms Page number 32>

 shown as being in line 18, contained - approximately 40 parts nitrogen per million.

   It should be noted that a part of the latter stream which contains hydrocarbons with a boiling point greater than about 343 C
 EMI32.1
 1 '; z ,: 11; #, .... can combine with the middle distillate fraction employed as the oil feed for the second reaction zone of the present process, at least up to the point, where the: content of nitrogen compounds of the resulting oil charge does not exceed
 EMI32.2
 not about: 0 parts per million. Other checks carried out on the various fractions are indicated in Table II which follows: TABLE II.



   Control of products starting from vacuum diesel.
 EMI32.3
 



  Fraction limit * 000 83-204 C 204-3 ° 3 C 3 ° 3 'C
 EMI32.4
 
<tb> Volume <SEP>% <SEP> of total <SEP> <SEP> 22.6 <SEP> 47.0 <SEP> 39.0
<tb>
<tb>
<tb> Specific <SEP> weight <SEP> to <SEP> 15.6 C <SEP> 0.7892 <SEP> 0.8373 <SEP> 0.8373
<tb>
<tb>
<tb> Distillation <SEP> ASTM <SEP> in <SEP> C
<tb>
<tb>
<tb>
<tb> ruin <SEP> of boiling <SEP> 116 <SEP> 219 <SEP> 354
<tb>
<tb>
<tb> 10% <SEP> 138 <SEP>, <SEP> 242 <SEP>. <SEP> 377
<tb>
<tb>
<tb>
<tb> 30% <SEP> 156 <SEP> 261 <SEP>. <SEP> 391 <SEP>
<tb>
<tb>
<tb> 50% <SEP> 160 <SEP> 277 <SEP> 407
<tb>
<tb>
<tb>
<tb> 90% <SEP> 182 <SEP> 321 <SEP> 463
<tb>
<tb>
<tb> extreme <SEP> <SEP> 203 <SEP> 345 <SEP> 488
<tb>
 
 EMI32.5
 Analysis of the type of hydrocarbon;

  "" '
 EMI32.6
 
<tb> Vol. <SEP>% <SEP>
<tb>
<tb> Paraffins <SEP> 41
<tb>
<tb> Naphthenes <SEP> 51
<tb> Olefins <SEP> 1
<tb>
<tb> Aromatics <SEP> 7
<tb>
   * The yield of light paraffinic hydrocarbons (C1 to C3) was 2.2% by weight and the fraction C4-83 C was 3.0 vol. %.



   To illustrate the second phase of the process according to the present invention, the boiling point hydrocarbons
 EMI32.7
 between 204 0 and 34300 were introduced into -. ,, ire

 <Desc / Clms Page number 33>

 reaction zone containing a catalyst comprising 6.0 wt% nickel (calculated as part) and a mixture of 75 wt% silica and 25 wt% alumina.



  The silica-alumina mixture was prepared by diluting 1610 fatty sodium silicate (28% by weight, BiO2) with 3220 cm3 of water, adding thereto 400 cm3 of hydrochloric acid, plus an additional 800 cm3 of water. The resulting acid-silica hydrosol was then added to 1580 cc of an aluminum sulfate solution with a specific gravity of 1.28 and was prepared starting from crystals of hydrated aluminum sulfate free of iron. The resulting alumina-silica hydrosol was then mixed with vigorous stirring with 1280 cm3 of an aqueous ammonium hydroxide solution containing 640 cm3 of a 28% by weight ammonia solution. The resulting hydrogel was filtered, slurried back into 8 liters of water, and dried.

   The dried material was subjected to various washing procedures with filtration, until the filtrate indicated a negative result for sulfate ions. The sulfate-free mixture was further dried at a temperature of 149 ° C., ground to a fine powder, and formed into 3.2 mm x 3.2 mm cylindrical pills.



  The pilues were subjected to calcination at high temperature in an air atmosphere for 3 hours and at a temperature of 649 C. An impregnation solution was then prepared by dissolving 60.0 fat of nickel nitrate hexahydrate in water, and diluting the resulting solution to about 700 ml with water. A 200 gram fraction of the alumina-silica mixture described was impregnated with the resulting impregnation solution in a rotary steam dryer. The dried catalyst was then calcined at an elevated temperature of 649 C.



  This catalytic converter has been placed in? reaction zone under the

 <Desc / Clms Page number 34>

 form of a fixed bed and maintained under an imposed pressure of 102 atmospheres. During the processing of the raw material consisting of the middle distillate, the inlet temperature to the reactor was maintained at a level of 327 ° C. The raw material was introduced into the reaction zone at a rate equivalent to a space velocity liquid hourly of 3.0 and was mixed with hydrogen in an amount of 534 normal liters per liter of oil in the charge.

   The entire effluent from the reaction zone was separated to give a hydrogen-rich gas stream, which was recirculated to combine with the mixed distillate forming the feed. The remaining normally liquid hydrocarbons, including light paraffinic hydrocarbons (C1 to C3) were subjected to fractionation in a laboratory column with several trays, and the results of this fractionation are shown in Table III which follows.



   TABLE III.



   Volumetric yields starting from middle distillate.
 EMI34.1
 
<tb>



  Constituents * - <SEP> Yield <SEP> Vol. <SEP>%
<tb>
<tb> Total <SEP> butanes <SEP> 7.9
<tb>
<tb>
<tb> Pentanes <SEP> and <SEP> hexanes <SEP> 15.3
<tb>
<tb>
<tb> Heptanes <SEP> to <SEP> 204 C <SEP> 47.2
<tb>
<tb>
<tb> 204 C <SEP> and <SEP> plus <SEP> heavy <SEP> 39.5
<tb>
 * Light paraffinic hydrocarbons (0 to C3), the yield was 0.67% by weight.



   The yields given in Table III are based on the amount of middle distillate that was charged, and it should be noted that the resulting light paraffinic hydrocarbons are practically negligible, as they represent only 0.67% by weight of the mixture. total load. It is

 <Desc / Clms Page number 35>

 furthermore to note that there was a yield by volume of 70.4% of hydrocarbons with a boiling point close to that of gasoline, including butanes, and a yield of 39.5% of hydrocarbons at a boiling point close to that of the middle distillate.

   This latter fraction can easily be put back into circuit to combine with the initial charge of middle distillate and these hydrocarbons are effectively put back into circuit, until exhaustion.



  EXAMPLE II.



   This example shows the applicability of the present process to a hydrocarbon fraction with a boiling point close to that of gasoline, the greater part of which boils within the limits of the boiling temperatures of the medium titillate. The feed was constituted by an East Texas kerosene having the properties shown in Table IV which follows.



   TABLE IV.



     Kerosene East Texas - Properties
 EMI35.1
 
<tb> Specific <SEP> weight <SEP> to <SEP> 15.6 C <SEP> 0.8189
<tb>
<tb> Distillation <SEP> ASTM <SEP> in <SEP> C
<tb>
 
 EMI35.2
 186 "initial boiling point,
 EMI35.3
 
<tb> 10% <SEP> 211
<tb>
<tb> 30% <SEP> '<SEP> 222
<tb>
<tb> 50% <SEP> 230
<tb>
<tb> 70% <SEP> 241
<tb>
<tb> 90% <SEP> 258
<tb>
<tb> Extreme <SEP> point <SEP> 283
<tb>
<tb>% <SEP> to <SEP> 204 C <SEP> 5.0
<tb>
 
 EMI35.4
 ce 3t'tOTfBn 0.8
 EMI35.5
 
<tb> Total nitrogen <SEP>, <SEP> ppm. <SEP> 3.6
<tb>
<tb> Sulfur, <SEP>% <SEP> in <SEP> weight <SEP> 0.036
<tb>
<tb>
<tb>
<tb> <SEP> Types of Hydrocarbons, <SEP> Vol.

   <SEP>%
<tb>
<tb> Paraffins <SEP>)
<tb>
 
 EMI35.6
 .aphtenes - S2.8
 EMI35.7
 
<tb> Olefins <SEP> 0.4
<tb>
 
 EMI35.8
 Aromatics 16, 8

 <Desc / Clms Page number 36>

 
The kerosene fraction was first introduced into a first reaction zone or cleanup reaction zone at a pressure of 54.2 atmospheres and an inlet temperature of 371 C. The feed was mixed with hydrogen in an amount of 178 normal liters per liter of oil, and contacted with the catalyst placed in the reaction zone at a liquid hourly space velocity of 5.0.

   The catalyst employed in the cleaning reaction consisted of cylindrical alumina pills having dimensions of 3.2mm x 3.2mm, which had been '' impregnated, using a single impregnation solution, with 2.0%. by weight of cobalt and 6.0% by weight of molybdenum, calculated as elements. Hydrogen sulfide, ammonia, and hydrogen were removed from the total reactor effluent in a high pressure separator, the hydrogen being recirculated to combine with the mixed hydrogen with the faction of kercene before its introduction into the cleaning reaction zone.

   The remainder of the effluent from the reaction zone passes to a fractionator where the light paraffinic hydrocarbons, methane, ethane, and propane have been removed and a stream of normally liquid hydrocarbons is obtained, containing butanes and components. heavier. This stream was then subjected to a further fractionation operation to give a butane fraction, a C5 hydrocarbon fraction having a final boiling point of 46 C, a C6 hydrocarbon fraction (46 C to 82 C), a fraction 82 C-204 C, and hydrocarbons with a boiling point exceeding 204 C.



   The fraction which boils above 204 C was then mixed with hydrogen in an amount of 534 liters.

 <Desc / Clms Page number 37>

 per liter of this oil fraction, and introduced at a liquid hourly space velocity of 1.0 into a second reaction zone or hydrocracking zone maintained at a pressure of 102 atmospheres and a temperature of about 302 C. the catalyst placed in this hydrocracking reaction zone comprised 0.4% by weight of palladium mixed with a cracking component consisting of 88% by weight of silica and 12% by weight of alumina.



  The total effluent from the reaction zone, from the hydrocracking reactor, was combined with the effluent from the first reaction zone after removal of ammonia and before separation of the light paraffinic hydrocarbons (CI to C3). Various checks of the product, and part of the resulting yields are given in Table V which follows.



   TABLE V.



   Inspection of kerosene charge products.
 EMI37.1
 
<tb>



  Fraction, <SEP> limits <SEP> in <SEP> <SEP> C <SEP> 82-204 0 <SEP> 204 =
<tb>
 
 EMI37.2
 specific roids at 15.6 C 0.7678 0.7: 301
 EMI37.3
 
<tb> Distillation <SEP> ASTM <SEP> in <SEP> <SEP> C
<tb> Boiling point <SEP> <SEP> 99 <SEP> 213
<tb>
<tb> 10% <SEP> 109 <SEP> 218
<tb>
 
 EMI37.4
 30% 2 '' '17 221
 EMI37.5
 
<tb> 50% <SEP> 126 <SEP> 225
<tb>
<tb> 70% <SEP> 142 <SEP> 231
<tb>
 
 EMI37.6
 90%, a,, 168, 246 95% .E z; k, s; i7 $ ¯ 254
 EMI37.7
 
<tb> Point <SEP> final <SEP>, <SEP> 191 <SEP> 274
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Analysis <SEP> of the <SEP> type <SEP> of hydrocarbons, <SEP> vol. <SEP>%
<tb>
 
 EMI37.8
 Piraffins '37'
 EMI37.9
 
<tb> Olefins <SEP> zero
<tb>
<tb> Naphthenes <SEP> 46 <SEP> -
<tb>
<tb> Aromatics <SEP> 17
<tb>
<tb> Numbers <SEP> octane
<tb>
 
 EMI37.10
 "F-1 Clear";

   , 'Y.6 9
 EMI37.11
 
<tb> "F-1, <SEP> + <SEP> 3 <SEP> ce. <SEP> TEL" <SEP> 83.1
<tb>
 

 <Desc / Clms Page number 38>

 
The portion of liquid product boiling up to 82 C, consisted of 33.3% by weight of butanes, 34.2% by weight of C5 :. 46 C and 32.6% by weight of C6 hydrocarbons (46 to 82 C). The octane number of the debutanized fraction up to an extreme temperature of 82 C was 82.4 "F-1 Clear", and 96.3 "F-1 + 3 cc TEL."
The fraction with a boiling point close to that of gasoline, boiling between 82 C and 204 C, was obtained in an amount of 53% by volume, based on the total charge in the first reaction zone.

   The characteristics of this fraction, as shown in Table V, are such that this fraction is ideally suited for the subsequent treatment in a catalytic reforming process to increase the! octane numbers, or its anti-explosive characteristics. It should be noted that the fraction is practically free of complete marriage of olefinic hydrocarbons and that it contains 17 by volume of aromatic hydrocarbons and 46% by volume of naphthenic hydrocarbons.



    : Example III.



   This example illustrates the possibility of applying the present process to the use of various light cycling oils, coming fully to the boiling point at a + temperature greater than the boiling point of the absence, and partially at a temperature above boiling point of the middle distillate. Two individual charges were treated separately by the method described in Example II; of them was an Oklahoma light cycling oil with boiling points between 231 C and 352 C. Other properties of these light recycling oils are given in Table VI below.

 <Desc / Clms Page number 39>

 



   TABLE VI Oklahoma and Leduc Recycled Light Oils - Properties.
 EMI39.1
 
<tb>



  Oklahoma <SEP> Leduc
<tb>
<tb>
<tb>
<tb>
<tb> Specific <SEP> weight <SEP> to <SEP> 15.6 C <SEP> 0.8849 <SEP> 0.8990
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Distillation <SEP> ASTM <SEP> in <SEP> C
<tb>
<tb>
<tb>
<tb>
<tb> Boiling point <SEP> initial <SEP> <SEP> 232 <SEP> 231
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 10% <SEP> 251 <SEP> 257
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 30% <SEP> 261 <SEP> 277
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 50% <SEP> 270 <SEP> 291
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 70% <SEP> 280 <SEP> 307
<tb>
<tb>
<tb>
<tb>
<tb> 90% <SEP> 293 <SEP> 327
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Point <SEP> final <SEP> 315 <SEP> 352
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>% <SEP> to <SEP> 204 <SEP> C <SEP> 0 <SEP> 0
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>% <SEP> "Bottoms" <SEP> 1.0 <SEP> 1.5
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Total nitrogen <SEP>, <SEP> ppm.

   <SEP> 285 <SEP> 245
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Sulfur, <SEP>% <SEP> in <SEP> weight <SEP> 0.70 <SEP> 0.69
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> <SEP> analysis of <SEP> type <SEP> of hydrocarbons,
<tb>
<tb>
<tb> Vol. <SEP>%
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Paraffins
<tb>
 
 EMI39.2
 Baphthens 50.7 43.4 Naphthenes 5 (), 7 43.4
 EMI39.3
 
<tb> Olefins <SEP> 3.7 <SEP> 5.4
<tb>
<tb> Aromatics <SEP> 45.6 <SEP>. <SEP> 51.2 <SEP>
<tb>
 
With respect to Oklahoma Cycling Light Oil, the catalyst employed in the first reaction zone or cleaning zone comprised 2.4 wt% nickel, 6.4 wt% molybdenum, and a mixture consisting of 88 wt% alumina and 12% by weight of silica.

   The second reaction zone or hydrocracking zone contained

 <Desc / Clms Page number 40>

 a catalyst consisting of 0.4% by weight of palladium,
 EMI40.1
 ., <>. i, .''- '' f .'- - '-? h' '-'. on a mixture of 8%. pot; ei ,,. cei, e, 7., - é, .. çiâ,. alumina. the zone of reâeion = '.. d' ziaoyâë was 'maiïîenue "' lj" v'4S, $ fiW.ô '>', 1 - at a pressure of 102 atmospheres, e one, entry of 39900 , and the load- a-: summer put in 'contact #'. , = E ', 1] ..> j J with the catalyst at a liquid hourly space velocity of 1.0. The light cycling oil was mixed with hydrogen in an amount of 356 normal liters per liter of oil, before it was admitted into the first reaction zone.

   The second zone or reaction zone
 EMI40.2
 4! ' k h, Y .. d4hydrocraauage was maintained a. at a pressure of 102 atmospheres, and at an inlet temperature of approximately 15 ° C, and the feed in this zone was contacted with the catalyst at a liquid hourly space velocity of 1.0 after was combined with hydrogen in the amount of 554 normal liters per liter of oil. The above operating conditions, in both reaction zones, were also employed during the treatment. a Leduc light cycling oil. -
 EMI40.3
 The control data of the various produ3sw.s4, inus of the light cycling oil Oklahoma pparaisn: in Table VII which follows.

 <Desc / Clms Page number 41>

 



   TABLE VII.



    Product center starting from light cycling oil
 EMI41.1
 Oklanoma - ';;. ..- 0 ... '(:,.,
 EMI41.2
 Fraction limits in 0 8g-204O 204 +
 EMI41.3
 
<tb> oids <SEP> specific <SEP> to <SEP> 15.6 0 <SEP> 0.7861 <SEP> 0.8222
<tb>
<tb>
<tb>
<tb>
<tb> Distillation <SEP> ASTM <SEP> in <SEP> <SEP> C
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> the initial boiling <SEP> <SEP> <SEP> 91 <SEP> 213
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 10% <SEP> 108 <SEP> 229
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 30% <SEP> 120 <SEP> 241
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 50% <SEP> 133 <SEP> 254
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 70% <SEP> 151 <SEP> 270
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> 90% <SEP> 178 <SEP> 292
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> anointed <SEP> final <SEP> 211 <SEP> 317
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Analysis <SEP> of

  <SEP> type <SEP> of hydrocarbons,
<tb>
<tb>
<tb> Vol. <SEP>%
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Paraffins <SEP> 18 <SEP> - <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Olefins <SEP> zero <SEP> - <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Naphthenes <SEP> 63 <SEP> - <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Aromatics <SEP> 19 <SEP> - <SEP>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Numbers <SEP> octane
<tb>
<tb>
<tb>
<tb>
<tb> "F-1 <SEP> Clear" <SEP> 70.7
<tb>
 
 EMI41.4
 "F¯1 + C cc. T :." 86,, 5.-
The fraction of product boiling up to 82 C contained 33.3% by weight of butanes, 35.5 by weight of C5 hydrocarbons at 46 C, and 31.2% by weight of '(16 and heavier hydrocarbons ( 46 C to 82 C).



     . The advantages resulting from the use of the present invention are readily apparent from the data in Table VII. The gasoline fraction at 82 C-204 C having a specific gravity of 0.7861 at 15.6 C is very suitable.

 <Desc / Clms Page number 42>

 for use as a feed in a subsequent catalytic reforming process. It should be noted as particularly significant the fact that this gasoline fraction contained a total of 82 by volume of precursors.
 EMI42.1
 , '1' .... <. ,,, '.:;,;.?' J aromatics in the form of Phthenes and aromatics, practically no olefinic hydrocarbons, and only 18% by volume of paraffinic hydrocarbons .

   In addition, this particular fraction showed a relatively high octane number even in the absence of further processing. The operations described in the examples above on !; been repeated on the various materials constituting the feeds in order to obtain the relation between the distribution of the product and the severity of the operation. To obtain this relation the severity of the operation was indicated by varying percentages of conversion to hydrocarbons boiling below 2040. Table VIII below shows the summary of the product distribution, for kerosene, for light cycling oils and for vacuum gas oil,

   determined with an operation severity resulting in a conversion of 60% by volume to hydrocarbons boiling below 204 C, and without recycling liquid to the process.

 <Desc / Clms Page number 43>

 
TABLE VIII.



  Summary of product distribution.
 EMI43.1
 
<tb> Load <SEP> E.Texas <SEP> Oklahoma <SEP> Oil <SEP> from <SEP> Wyo.-W.Tex.
<tb>
<tb>



  Kerosene <SEP> Oil <SEP> for <SEP> cycling <SEP> Vac.Gazoil
<tb>
<tb> cycling <SEP> Iéduo
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Distribution <SEP> of the
<tb>
<tb>
<tb> product
<tb>
<tb>
<tb>
<tb> C1 <SEP> to <SEP> C3, <SEP>% <SEP> in <SEP> weight <SEP> 1.0 <SEP> 1.7 <SEP> 1.0 <SEP> 0.9
<tb>
<tb>
<tb>
<tb>
<tb> C4 <SEP> to <SEP> 82 C, <SEP>% <SEP> en <SEP> vol. <SEP> 16 <SEP> 19 <SEP> 15 <SEP> 23
<tb>
<tb>
<tb>
<tb> 82 C-204 C, <SEP>% <SEP> en <SEP> vol. <SEP> 53 <SEP> 57 <SEP> 64 <SEP> 58
<tb>
<tb>
<tb>
<tb> 204 C <SEP> and <SEP> plus <SEP> heavy <SEP>%
<tb>
<tb> in <SEP> vol. <SEP> 40 <SEP> 40 <SEP> 40 <SEP> 40
<tb>
<tb>
<tb>
<tb>
<tb> Total <SEP> C4 <SEP> + <SEP> yield
<tb>
<tb> referral.

   <SEP> 109 <SEP> 116 <SEP> 119 <SEP> 121
<tb>
 
It may be noted at once that in all four cases the production of the light paraffinic hydrocarbons was extremely low, in no case amounting to more than 2.0% by weight of the total charge in the treatment process. Even more significant is the fact that in all cases, a volumetric gain has been observed in the total yield of butanes and of heavier hydrocarbons. In the case of the East Texas kerosene fraction, the total yield of butanes and heavier hydrocarbons, including those boiling above 204 C, was 109.9% by volume. The greatest volumetric increase was obtained when treating gas oil under vacuum, and was 121%.

   Thus, the possibility of applying the process according to the present invention by treating feeds entering the boiling point at temperatures above the boiling point of gasoline, was easily recognized.



   The fact that the present invention offers special advantages when dealing with heavier hydrocarbons, such as

 <Desc / Clms Page number 44>

 shown by Wyoming-West Texas vacuum gasoline, is very clearly proven.



    CLAIMS.



   1. A process for the catalytic hydrocracking of hydrocarbons comprising reacting a stream of a hydrocarbon oil feed which boils predominantly above 2040 and contains nitrogen compounds, in a first zone. reaction with hydrogen in the presence of a catalyst insensitive to nitrogen with formation of ammonia starting from said nitrogenous compounds, removal of the ammonia from the effluent of the first reaction zone, then separation outside said effluent of a light normally liquid fraction having an extreme boiling point of between 204 C and 232 C and also separation from said effluent of a heavier fraction containing constituents of the effluent which come to a boil.

   between the final boiling temperature of said light fraction and 343 C, -, - reacting a stream of said heavier fraction in a second reaction zone with hydrogen in the presence of a catalyst d 'hydrocracking sensitive to nitrogen, and mixing at least the normally liquid portion of the effluent from the second reaction zone with the normally liquid portion of the effluent from the first reaction zone before the separation of said fraction light of this effluent.


    

Claims (1)

2. Method according to claim 1, characterized in that the mixture of normally liquid constituents of the effluents from the first reaction zone and from the second reaction zone is separated into a first fraction having a final boiling point of between 204 C and 232 C, a second <Desc / Clms Page number 45> fraction having a final boiling point between 343 C and 371 C, and a third fraction containing the hydrocarbons of the mixture which come to the boil above the second fraction, a stream of the second fraction is reacted with hydrogen in the presence of the nitrogen-sensitive catalyst in the second reaction zone, and at least a part of the third fraction is subjected together with the hydrocarbon oil feed to the reaction with hydrogen in the presence of the nitrogen insensitive catalyst in the first reaction zone. 3. Method according to claim 2, characterized in that a portion of the third fraction is mixed with the stream of the second fraction which is fed into the second reaction zone so that the hydrocarbon mixture entering this second reaction zone contains less than 5 parts of nitrogen by weight per million parts by weight of the mixture and that all of the remaining portion of the third fraction is mixed with the hydrocarbon oil feed which is introduced into the first reaction zone. 4. Method according to any one of claims 1 to 3, characterized in that the hydrocarbon oil feed is contacted with the nitrogen-insensitive catalyst in the first reaction zone at a space velocity between 0, 5 and 10 volumes, measured as liquid, per hour and per volume of catalyst together with an amount between 178 and 1425 normal liters of hydrogen per liter of oil, measured in liquid form, and at a temperature between 260 C and 538 C and at an input pressure of 204 atmospheres, and the hydrocarbon stream introduced into the second reaction zone is contacted with the catalyst. <Desc / Clms Page number 46> sensitive to the nitrogen therein, at a space speed between 1 and 15 volumes, measured in liquid form, per hour and by volume of catalyst together with 178 to 1070 normal liters of hydrogen per liter of oil, measured in liquid form, and at a temperature between 260 C and 51000 and under a pressure between between 68 and 204 atmospheres. 5. Method according to claim 4, characterized in that the reaction of the hydrocarbons with the hydrogen takes place in the second reaction zone at a higher hourly space velocity than in the first reaction zone and at a temperature which is 28 at 83 C lower than the temperature which is maintained in the first reaction zone. 6. -Procédé according to any one of claims 1 to 4, characterized in that the reaction in the first reaction zone is carried out in the presence of a catalyst containing between 4.0% and 45.0% by weight of molybdenum and between 0.2 and 10.0% by weight of nickel and cobalt group metal on a support consisting at least predominantly of alumina and not containing more than 12% by weight of silica. 7. Process according to any one of claims 1 to 6, characterized in that the reaction in the second reaction zone is carried out in the presence of a catalyst which contains between 0.5% and 10% by weight of nickel on a support prepared by synthesis consisting predominantly of silica and containing between 12 and 25% by weight of alumina. 8. Process according to claim 7, characterized in that the catalyst contains approximately 6% by weight of nickel on a support consisting substantially of 75% by weight of silica and 25% by weight of alumina. <Desc / Clms Page number 47> 9. Process according to any one of claims 1 to 6, characterized in that the reaction in the second reaction zone is carried out in the presence of a catalyst which contains between 0.1 and 5.0% by weight of a a platinum group metal on a support consisting predominantly of silica and containing from 12 to 25% by weight of alumina. 10. Process according to claim 9, characterized in that the catalyst contains between 0.1 and 2.0% palladium on a support consisting substantially of 88% by weight of silica and 12% by weight of alumina. 11. A method according to any one of claims 1 to 10, characterized in that a hydrocarbon oil feed boiling between 204 C and 538 C, and containing an appreciable amount of nitrogenous contaminants; is brought into contact in the presence of hydrogen with the catalyst insensitive to nitrogen in the first reaction zone at a space velocity of between 0.5 and 3 volumes of oil, measured in liquid form, per hour and per volume catalyst, a fraction having an initial boiling point between 204 and 232 C ,: a point. with a final boiling point of not less than 343 C, and a nitrogen content of not less than 1 part by weight per million parts by weight of said fraction, is separated from the mixture of normally liquid constituents of the effluents of the two reaction zones, and a stream of said fraction is fed as a stream of hydrocarbons into the second reaction zone at a space velocity which is higher than that employed in the first reaction zone and is greater than a volume of oil, measured under liquid form, per hour and per volume of nitrogen-sensitive catalyst in said second reaction zone. - <Desc / Clms Page number 48> 12. Processes hydrocracking, substantially as EMI48.1 described with reference to the attached drawing. 'l¯ ..;] Ôj (; 1' \:;. ; .. 1jtc;. ",", ..; ', 7 "\. V r; 1' '" i' '' f, '' \ $: - .. '; = ..'