US3843510A - Selective naphtha hydrocracking - Google Patents

Abstract

1. A PROCESS COMPRISING CONTACTING A GASOLINE BOILING RANGE VIRGIN NAPHTHA WITH A CATALYST CONSISTING ESSENTIALLY OF ZSM-5 TYPE OF ALUMINO-SILICA ZEOLITE HAVING A HYDROGENATION/DEHYDROGENATION COMPONENT THEREIN IN ADMIXTURE WITH ADDED HYDROGEN IN A HYDROGEN TO HYDROCARBON RATIO OF ABOUT 1 TO 10, AT ABOUT 600 TO 800*F., 50 TO 1000 P.S.I.G. AND 0.5 TO 10 WHSV, UNDER SUCH COMBINATION OF CONDITIONS AS TO HYDROCRACK AT LEAST ABOUT 40 WT. PERCENT OF SAID VIRGIN NAPHTHA TO PENTANE AND LIGHTER PRODUCTS HAVING A C3 TO C4 RATIO OF ABOUT 1.0 TO 1.4, AND AN N-C4 TO I-C4 RATIO OF ABOUT 0.85-1.2; WHICH PROCESS ALSO PRODUCES UP TO ABOUT 60 WT. PERCENT OF A C6+ LIQUID PRODUCT HAVING A MINIMUM CLEAR RESEARCH OCTANE NUMBER OF ABOUT 80, WHICH LIQUID PRODUCT HAS AN OCTANE NUMBER OF AT LEAST ABOUT 40 UNITS HIGHER THAN SAID FEED.

Description

nt. 22, 1974 RQA, MORRlsQN ETAL SELECTIVE NAPHTHA HYDROCRACKING auna ual-ch 2s. 1973 i s 'sheets-sheet 1 A g +I) Sele-activ H ydrocrackmg Plant Oct. 22, 1974 R, A, MORRlSON ETAL 3,843,510

SELECTIVE NAPHTHA HYDROCRACKING I5 Sheets-Sheet 5 Filed Ilarch 23, 1973 m\\ w38 E03 United States Patent 3,843,510 SELECTIVE NAPHTHA HYDROCRACKING Roger A. Morrison, West Deptford, NJ., and John J. Wise, Media, Pa., assignors to Mobil Oil Corporation Filed Mar. 23, 1973, Ser. No. 344,453 Int. Cl. Cg 13/10 U.S. Cl. 208-111 10 Claims ABSTRACT OF THE DISCLOSURE A process for converting virgin straight run naphtha to a gas which is predominantly saturated C3-C5 and a C6+ liquid which has a substantially higher octane number than the feed. The process includes contacting the virgin straight run naphtha together with added hydrogen with a catalyst of the ZSM-S type aluminosilicate zeolite containing a hydrogenation/dehydrogenation component at relatively mild temperatures and space velocities, and pressure high enough to induce hydrocracking. The gas product can be used as such as I PG (liquified petroleum gas) or as feed to a pyrolysis unit for cracking to olefins, particularly ethylene, propylene and some higher homologues.

This invention relates to hydrocarbon conversion. It more particularly refers to conversion of naphtha into mode desirable products.

It is known to crack virgin straight run naphtha C6 to 330 F. stock, under conditions such as to produce a gas product, in which ethylene and propylene predominate, and a liquid product boiling in the gasoline range known as pyrolysis gasoline. This pyrolysis gasoline is rich in aromatics and as such is conveniently blendable into a refinery gasoline pool.

Recently, government actions in various parts of the world have necessitated a reduction in the benzene content of gasoline sold in such localities and therefore, indirectly these actions have limited the amount of pyrolysis gasoline which can be blended directly into the gasoline pool without prior removal of at least some of the benzene therefrom. This limit on the tolerable benzene limits in turn forces the petroleum refiner to produce less pyrolysis gasoline, which means a concommitant reduction in light oleiins production, or it requires the reliner to further treat produced pyrolysis gasoline, e.g. by distillation, to remove all or part of the benzene content thereof. Neither of these solutions are satisfactory from an economics point of view because on the one hand the pyrolysis unit is operating at substantially less than capacity and therefore inefficiently, and on the other hand sepbenzene must be cleaned up and disposed of for chemicals use, if possible, or burned in the refinery for its heat value.

Liquified petroleum gas (LPG) is a commodity petroleum product. It is used principally in the home and remote (camping and trailering) locations for providing heat for comfort and for cooking. Although the demand for LPG is not presently so great in the United .States that this demand cannot be satisfied from available petroleum fractions, it is anticipated that this demand will continually rise in the near future. In some parts of the world, there is a substantially larger proportional demand for LPG. In some cases this demand exceeds the quantity of LPG which can reasonably be recovered from petroleum without chemical processing (e.g. cracking or reforming). LPG is principally propane which may have Patented Oct. 22, 1974 more or less ethane, propylene and/or butane admixed therewith.

One specification for commercial LPG is:

Tests 1 Limits Vapor pressure at 100 F., p.s.i.g., Max. 200. Boiling Pt., F., Max 37. Volatile Sulfur, gr./ C F., Max.2 15.

Corrosion, l Hr. at 100 F., ASTM Strip Max. 1. Dryness, Cobalt Bromide Test3 Pass. HZS, Lead Acetate Test4 Do. Residue Test Do. Oil Ring Test Do. Odorization, lbs. Ethyl Mercaptan/ 10,000 gal. 1.5. Composition:

Propane and/ or Propylene, percent, Min. 95. Ethane, percent, Max 3.

1 Test methods are given in NGPA publication 2140.

2 Test shall be run before odorizing the product.

.If Dew Point Test is used, Dew Point lower than 15 mdleates moisture free product.

4Proposed ASTM method for detection of HQS in LPG.

It is known to use various zeolite catalysts to accomplish various hydrocarbon conversions. Small pore (less than about 5 Angstrom Units) zeolites are considered to be shape selective catalysts because they will act on straight chain (normal) parafiins while passing isoparaffins substantially unaltered. Large pore (over about l1 Angstrom units) zeolites are not shape selective in that they will admit and catalytically act upon substantially all of the hydrocarbons in usual petroleum feedstocks regardless of configuration.

More recently there has been developed an intermediate type of zeolitic material which seems to have an eliptical pore opening of such size and shape as to be able to admit not only normal parains, but slightly branched materials as well. This newer type of material is known as a ZSM-S type of synthetic aluminosilicate zeolite.

ZSM-S aluminosilicate zeolitic material is a family of catalytic materials which includes not only ZSM-S itself but also ZSM-8, ZSM-11, and other similarly behaving zeolites.

`ZSM-S is disclosed and claimed in copending application Ser. No. 865,472, filed Oct. 10, 1969; ZSM-S is disclosed and claimed in copending application Ser. No. 865,418, filed Oct. 10, 1969, and ZSM-11 is disclosed and claimed in copending application Ser. No. 31,421 filed Apr. 23, 1970.

The family of ZSM-S compositions has the characteristic X-ray diffraction pattern set forth in Table 1 hereinbelow. ZSM-5 compositions can also be identified, in terms of mole ratios of oxides, as follows:

gallium, Y is selected from the group consisting of silicon and germanium, z is from 0 toi-40 and b is at least 5 and `preferably 15-300. I n a preferred synthesized form, the

zeolite hasv a formula, in terms of mole ratios of oxides, as follows:

- 0.9 :l: 0.2M2 0: A1203: 15-100SiO2I2Hz0 and M is selected from the group consisting of a mixture of alkali metal cations, especially sodium and alkyl ammonium ions, especially tetraalkylammonium cations, the alkyl groups of which preferably contain 2-5 carbon atoms. l

In a preferred embodiment of ZSM-S, W is aluminum, Y is silicon and the silica/alumina mole ratio is at least 15, preferably at least 30. v

Members of the family of ZSM-S zeolites which include ZSM-S, ZSM-8 and ZSM-ll possess a definite distinguishing crystalline structure Whose X-ray diffraction pattern shows the following significant lines:

These values, as well as all other X-ray data were determined by standard techniques. The radiation was the K- alpha doublet of copper, and a scintillation counter spectrometer with a strip chart pen recorder was used. The peak heights, I, and the positions as a function of 2 times theta, where theta is the Bragg angle, were read from the spectrometer chart. From these the relative intensities, 100 I/Io where I0 is the intensity of the strongest line or peak, and d(obs.), the interplanar spacing in A, corresponding to the recorded lines, were calculated. In Table 3 the relative intensities are given in terms of the symbols S=strong, M=medium, MS=medium strong, MW=me dium weak and VS=very strong. It should be understood that this X-ray dilraction pattern is characteristic of all the species of ZSM-S compositions. Ion exchange of the v a composition, in terms of mole ratios of oxides, falling within the following rangestj TABLE 2 Parueularly f Broad Preferred preferred oH-/Si02 nor-1.0 0.1-0.8 i12-(L75 RrN-t/(RiNH-Naf) 0.2-0.95 0.3-0.9 v0.4-0.9 Hgo/olaz 10-300 10-300 10-300 Yor/Wzoa 5-100,A -1osc tti-4o wherein R is propyl, W is aluminum and Y is silicon. This mixture is maintained at reaction conditions. untilI the crystals of the zeolite are formed. Thereafter the` crystals are separated from the liquid and recovered. Typical reaction conditions consist of a temperature of from about C. to 175 C. for a period of about six hours to 60 days. A more preferred temperature range is from about 4 to 15 0" C., with the amount of time at a temperature in such range being from about 12 hours to 20 days.

The digestion of the gel particles is carried out until crystals form. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water Washing.

ZSM-S is preferably formed as an aluminosilicate. The composition can be prepared utilizing materials which supply the elements of the appropriate oxide. Such compositions include, for an aluminosilicate, sodium aluminate, alumina, sodium silicate, silica hydrosol, silica gel, silicio acid, sodium hydroxide and tetrapropylammonium hydroxide. It will be understood that each oxide component utilized in the reaction mixture for preparing a member of the ZSM-S family can be supplied by one or more initial reactants and they can be mixed together in any order. lFor example, sodium oxide can be supplied by an aqueous solution of sodium hydroxide, or by an aqueous solution of sodium silicate; tetrapropylammonium cation can be supplied by the bromide salt. The reaction mixture can be prepared either batchwise or continuously. Crystal size and crystallization time of the ZSM-S composition will vary with the nature of the reaction mixture employed.

ZSM-S can also be identied, in terms of mole ratios of oxides, as follows:

mlm

wherein M is at least one cation, n is the valence thereof and z is from 0 to 40. In a preferred synthesized form, the zeolite has a formula, in terms of mole ratios of oxides, as follows:

Ello

and M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetraethylammonium cations.

Zeolite ZSM-8 can be suitably prepared by reacting a water solution containing either tetraethylammoniumhydroxide or tetraethylammonium bromide together with the elements of sodium oxide, aluminum oxide, and an oxide of silica.

The operable relative proportions of the various ingredients have not been fully determined and it is to be immediately understood that not any and all proportions of reactants will operate to produce the desired zeolite. In fact, completely different zeolites can be prepared utilizing the same starting materials depending upon their relative concentration and reaction conditions as is set forth in U.S. 3,308,069. In general, however, it has been found that when tetraethylammonium hydroxideis employed, ZSM-S can be prepared from said hydroxide, sodium oxide, aluminum oxide, silica and water by reacting said materials in such proportions that the forming solution has a composition in terms of mole ratios of oxides falling within the following ranges: I

Thereafter, the crystals are separated from the liquid and recovered. Typical reaction conditions consist of maintaining the foregoing reaction mixture at a temperature of from about C. to 175 C. for a period of time of from about six hours to 60 days. A more preferred hydroxidefrom about 80 to temperature range is from about to 175 C. with the amount of time at a temperature in such range being from about 12 hours to 8 days.

ZSM-ll can also be identified, in terms of mole ratios of oxides, as follows:

wherein M is at least one cation, n is the valence thereof and z is from 6 to 12. In a preferred synthesized form, the zeolite has a formula, in terms of mole ratios of oxides, as follows:

o. ein. 3M 2 ozAnoamO-aosiozznro and M is selected from the group consisting of a mixture of alkali metal cations, especially sodium, and tetrabutylammonium cations.

ZMS-l1 can be suitably prepared =by preparing a solution containing (R4X)2O, sodium oxide, an oxide of aluminum or gallium, an oxide of silicon or germanium and water and having a composition, in terms of mole ratios of oxides, falling within the following ranges:

wherein R4X is a cation of a quaternary compound of an element of Group 5A of the Periodic Table, W is aluminum or gallium and Y is silicon or germanium maintaining the mixture until crystals of the zeolite are formed. Preferably, crystallization is performed under pressure in an autoclave of static bomb reactor. The temperature ranges from 100 C.-200 C. generally, but at lower temperatures, e.g. about 100 C. crystallization time is longer. Thereafter the crystals are separated from the liquid and recovered. The new zeolite is preferably formed in an aluminosilicate form.

An embodiment of this catalyst resides in the use of a porous matrix together with the ZSM-S type family of zeolite previously described. The zeolite can be combined, dispersed, or otherwise intimately admixed with the porous matrix in such proportions that resulting products contain from 1 to 95% by weight and preferably from 10 to 70% by weight of the zeolite in the final composite.

The term porous matrix includes non-zeolite inorganic compositions with which the zeolites can be combined, dispersed or otherwise intimately admixed wherein the matrix may be catalytically active or inactive. It is to be understood that the porosity of the composition employed as a matrix can be either inherent in the particular material or it can be introduced by mechanical or chemical means. Representative of matrices which can be employed include metals and alloys thereof, sintered metals, and sintered glass, asbestos, silicon carbide, aggregates, pumice, rebrick, diatomaceous earths, alumina and inorganic oxides. Inorganic compositions, especially those comprising alumina and those of a siliceous nature are preferred. Of these matrices inorganic oxides such as clay, chemically treated clays, silica, silica alumina, etc. as well as alumina, are particularly preferred because of their superior porosity, attrition resistance and stability.

Techniques for incorporating the ZSM-S type family of zeolites into a matrix are conventional in the art and are set forth in U.S. 3,140,253.

1t is to be noted that when a ZSM-S type zeolite is used in combination with a porous matrix, space velocities which may be set forth as parameters for a process using such material are based on the ZSM-S type zeolite alone and the porous matrix is ignored. Thus, whether a ZSM-S type zeolite is used alone or in a porous matrix, the space` velocities in al1 cases refer to the ZSM-5 type component` It is known that zeolites, particularly synthetic zeolites, can have their composition modified by impregnating certain metals thereonto and/or thereinto. The composition can also be modified by exchanging various anions and/or cations into the crystal structure of the zeolite, replacing more or less of the ions originally present upon production of the zeolite.

Typical cations replacing the original sodium or part of the sodium include hydrogen, ammonium, and metal cations, including mixtures of these. Of the replacing cations, preference is given to hydrogen, ammonium, rare earth, metals, magnesium, zinc, cadium, calcium, nickel rhenium and mixtures thereof.

Typical ion exchange techniques would be to contact a ZSM-S type of zeolite with a salt of the desired replacing cation or cations. Although a wide variety of salts can be employed, particular preference is given to chlorides, nitrates and sulfates.

Representative ion exchange techniques are disclosed in a wide variety of patents, including U.S. 3,140,249; 3,140,- 251; and 3,140,253

As noted above, it is possible to incorporate a desired metallic component onto the ZSM-S type family of zeolites by techniques other than ion exchange Thus, for example, it is possible to impregnate a desired metallic component, such as zinc, platinum or palladium thereinto by conventional impregnation techniques, as well as merely depositing the elemental metal onto the particular zeolite and in some cases, such as with zinc oxide, to incorporate the metal by physical admixture of the zeolite with a substantially insoluble compound of the metal.

In any event, following contact with a salt solution of the desired replacing cation, the zeolites are preferably Washed with water and dried at a temperature ranging from to about 600 F. and thereafter heated in air or inert gas at temperatures ranging from about 500 W. to 1500" F. for periods of time ranging from 1 to 48 hours or more. It is noted that this heat treatment can be carried out in situ, i.e. while the particular reaction being catalyzed by the ZSM-5 type of zeolite is taking place, but it is preferred to carry it out as a separate step prior to carrying out the reaction.

ZSM-S type of zeolites have been disclosed to be useful in aromatizing petroleum fractions, boiling up to about 380 F. which are parainic, olenic and/or naphthenic in nature, by treating these fractions at about 650 to 1500 F. under high severity conditions in the absence of added hydrogen (see Applications Ser. Nos.. 153,885 and 253,942 led June 16, 1971 and May 17, 1972 respectively). These zeolites containing a hydrogenation/dehydrogenation component have also been disclosed as useful catalysts in dewaxing 350 F.| fractions by treating such at about 650 F. to 1000 F., 100 to 300 p.s.i.g., a space velocity equivalent to about 0.1 to 10 LHSV and an added hydrogen to hydrocarbon ratio of between about 1 and 20. In the aromatization process referred to above, a substantial portion of the feed is converted to a C5 gas (pentanes and lighter).

It is an object of this invention to provide a novel process of converting virgin straight run naphtha to more desirable products.

It is another object of this invention to provide a process of converting virgin straight run naphtha to lower olens and high octane gasoline while minimizing benzene production.

It is a further object of this invention to provide a process of converting virgin straight run naphtha to a high octane gasoline blend stock having a low sulfur and a low benzene content.

lA still further object of this invention is to produce a synthetic LPG which is compatible with natural LPG.

Other and additional objects of this invention will become apparent from a consideration of this entire specication including the drawing and the claims hereof.

Understanding of this invention will be facilitated by reference to the accompanying drawing in which:

iFIG. 1 is a schematic dow sheet showing one process according to this invention;

FIG. 2 is similar to FIG. 1 showing a modified process in accord with this invention; and

FIG. 3 is similar to FIG. 1 showing a modified process in accord with this invention.

In accord with and fulfilling these objects, one aspect of this invention resides in a process comprising contacting a gasoline boiling range virgin straight run naphtha with a ZSM-S type of synthetic aluminosilicate zeolite catalyst containing a hydrogenation/dehydrogenation component at an elevated temperature of about 600 to 800 F., an elevated pressure of about S to 1000 p.s.i.g., a space velocity of about l0.5 t0 l0 WHSV and an added hydrogen to hydrocarbon ratio of about 1 to 10 under such combination of these conditions as to hydrocrack said naphtha into a C gaseous fraction and a Csi' liquid fraction at a conversion of at least about 40% in a gas to liquid ratio of about l to 2; with the liquid fraction having a benzene content of less than about 5%, and with the gas fraction containing a C3 to C4 ratio of about 1.0 to 1.4, an n-C4 to i-'C4 ratio of about 0.85 to 1.2.

The liquid product produced according to this process is remarkably good gasoline blend stock, it having a clear research octane number of at least about 91. Under some reaction conditions, that is higher severity at a conversion of at least about 75%, it is practical to produce a C5+ liquid gasoline product having a still higher clear research octane number of at least about 94.

Preferred operating conditions for the virgin naphtha hydrocracking process of this invention are: temperature 625 to 725 F.; pressure 500 to 800 p.s.i.g.; space velocity 1 to 5 LHSV; and added hydrogen to hydrocarbon ratio 4 to 6.

The ZSMS type of catalyst used in the instant process must have a hydrogenation/dehydrogenation component therein. This component can be incorporated by impregnation and/ or ion exchange as desired. The proportion of such component should be about 0.1 to 1.0% by Weight based upon the weight of the zeolite portion of the catalyst mass. Exemplary hydrogenation/dehydrogenation components which are useful in the practice of this invention include metals, oxides and sulides of metals of the Periodic Table which fall in Group VIB including chromium, molybdenum, tungsten and the like Group IIB including zinc and cadmium. Group VIIB including manganese and rhenium, Group VIII including cobalt, nickel, platinum, palladium, ruthenium, rhodium, rhenium and the like, and combinations of metals, suliides and oxides of metals of Groups VIb and VIII such as nickel-tungsten sulfide, cobalt molybdenum oxide and the like. These hydrogenation/dehydrogenation components are especially illustrated by nickel, palladium, platinum, ruthenium, rhenium, cobalt, zine and the like. Under some circumstances a very strong hydrogenation/dehydrogenation component such as nickel is preferred Whereas under other circumstances a milder acting catalyst such as zinc may l be more desirable. This depends to a great extent upon the temperature and pressure of the hydrocracking processs and the tolerable limits of aromatic's, as opposed to naphthenes, in the liquid product. Y.

The products produced by this mild hydrocracking of the naphtha feed in contact with ZSM.-5 type of zeolite catalyst are excellent products Without further processing. As noted above, the liquid product is very good gasoline. 'Ihe gas product produced under 'these hydrocracking conditions is an unusually excellent material for conversion to LPG. In this aspect of this invention, this gas is separated into a Cl-CZ fraction and a C3-,C5 fraction. The C1-C2 fraction is suitably used or sold for fuel while the C3-C5 fraction is condensed to LPG. In a preferred embodiment of this aspect of this invention it has been found to be quite suitable to separate an iso-C4 fraction from the (i3-C5 gas fraction and to use this fraction as feed for alkylation.

In another aspect of this invention the gas product produced by this mild hydrocracking is not resolved but is fed in its entirety to -a pyrolysis unit which may be operl ated conventionally to maximize the production of olens and hydrogen. This pyrolysis has as its main purpose to convert the C5 gas product of hydrocracking to predominantly C2 'and C3 oleiins, perhaps with some olenic C4 content, and produce some liquid pyrolysis gasoline byproduct. One of the most desirable things about this combination of process steps, as opposed to direct pyrolysis of straight run naphtha without intermediate hydro-l cracking, is that less pyrolysis gasoline is produced upon cracking the C5 gas produced by hydrocracking than with straight run naphtha feed for the same equivalent ethylene production. Blending the hydrocracked gasoline with the pyrolysis gasoline gives acceptable total yields of gasoline with reasonably high octane numbers without the` adversity of high benzene content.

A further aspect of this invention is in using the gasoline produced in this process, hydrocracked liquid product, pyrolysis gasoline or both, as reformer feed. Mild reforming of this product increases the octane value thereof without excessive loss of volume or production of benzene. Further, since the liquids produced by the process of this invention are very low in sulfur content, they do not need pretreating before being reformed.

A byproduct of pyrolysis is hydrogen generated in olelins production. This hydrogen can be used as the necessary added hydrogen feed to the hydrocracking unit referred to above. Where necessary or desirable, additional quantities of hyrogen can be fed to the hyrocracking unit from other sources or some of the hydrogen produced during pyrolysis can be separated for other uses in order to provide the correct, desired hydrogen to hydrocarbon ratio.

Referring now to FIG. l, a virgin straight run naphtha 10, such as C5330 F. light Arabian stock, is fed to a hydrocracking converter 12 containing a suitable quantity of a ZSM-S type catalyst 14. Hydrogen 16 is also fed into the converter 12. There are produced in the converter 12 a C54' liquid product 18 gas product which is suitably split into a Cl-C2 fraction 19, an iso-C4 fraction 20 which may be fed to alkylation, and the remaining Ca-C., fraction 21 which is used as LPG.

As shown in FIG. 2, the liquid product 18 is gasoline blend stock while the unresolved gas product 22 may be fed to a pyrolysis unit 23, which may be thermal or catalytic in nature (the unit shown is of the catalytic 24 variety). There are produced in the pyrolysis unit pyrolysis gasoline liquid product 26, anda mixed gas product 27 which is rich in olefins and hydrogen. The liquid pyrolysis gasoline product 26 maybe separately used or it may be blended with the C5+ liquid product 18 from the hydrocracking converter 12 to form `a total gasoline range product 30.

The olens stream 28 evolved from pyrolysis is suitably resolved by 4known techniques in a gas plant operation 32 which may include distillation and/or extraction opera tions. There are produced from this gas plant 32 a hydrof gen stream 16, part or all of which is recycled to the hydrocracker 12, a light gas stream 34 which may be rich in methane and therefore can be used as fuel or perhaps vented,an ethylene stream 36 and a higher olefins stream 38 which is predominantly propylene having some proportion of butylenes and/or pentylencs admixed there-v with. This higher olefins stream may be further resolved to produce high'grade propylene and other oletins as desired. Y

Referring now to FIG. 3, a virgin straight run` naphtha 50 is fed into contact with a ZSM-S type catalyst 52 together with hydrogen 54 under hydrocrackingconditions in a converter 56. There are produced in the converter 56,

a C1C2 gas 57 and a C3C4 gas 58 which is fed to a pyrolysis unit 60 which in turn produced a liquid pyrolysis gasoline product 62 and a gas product `64. The converter 56 also produces a liquid product 66 which is relatively high octane gasoline. This C5+ liquid 66 is fed to a reformer 68 for mild reforming in or-der to increase the octane value even more without significantly reducing the volume of the liquid product but still producing a reformer gas effluent containing mainly hydrogen and Cf. This gas can be recovered and used as fuel or fed to the pyrolysis unit 60 as Idesired.

This liquid reformate 70 is suitably blended with pyrolysis gasoline 62 to form' a gasoline product 72. It may alternatively be desirable to blend the pyrolysis gasoline 62 with the hydrocracking C5+ liquid 66 before reforming 68.

The gas product 64 of pyrolysis is an olens rich material which is resolved in a splitting operation 74 into recycle hydrogen 54, light gases 76, ethylene 78` and higher oleiins 80.

This invention will be illustrated by references to the following examples which are not to be construed as limiting on the scope hereof. In these examples parts and percentages are by weight unless specified to the contrary.

EXAMPLE 1 A virgin light Arabian-naphtha charge stock having the following characteristics: Y

Charge, Arabian Naphtha Gravity, API 63.2 Sp. Gr. 60/60 F 0.7268 Sulfur, p.p.m 290 Octane Number, C6+:

R+3 64 R-l-O 40 C6+ PONA Analysis:

Total Parains 63.5 Total Olens Monocycloparains 19.2 Dicycloparans 0.9 Cyclooleiins 0 Total Naphthenes 20.1 Alkylbenzenes 16.3 Indanes and Tetralins 0.1 Naphthalenes 0 Total Aromatics 16.4 Parain Distribution:

C5 0.1 C6 9.1 Cf, 14.4 C8 15.9 C9 17.8 C10 5.5 Cn 0 C12 0 Aromatic Distribution:

C8 0.7 C, 3.3 C8 6.5 C9 5.5 C10 0.4 Combined Hydrogen 14.55 MolecularA` Weight:

7. Parains v y 110.1 Aromatics 105.9 Dicycloparains 1 l 3 .3 C6+ Total 109.3

was hydrocracked by contacting such with hydrogen and a ZSM-S catalyst having a silicon to aluminum ratio of at 650 to 665 F. ata pressure of about 650 p.s.i.g. for about two (2) weeks. The space velocity was Amaintained at about 3 and the hydrogen feed was sulicient to provide a hydrogen toV hydrocarbon ratio of about 5 to 1.

10 The catalyst which was used had been pretreated with hydrogen at 650 p.s.i.g. and 900 F. for 1 hour. The hydrogenation/dehydrogenation component was nickel, which was present in a proportion of 0.4%.

The following Table 2 sets forth the properties of the C5- gas product:

Wt. percent of total Percent of C5- product Properties of liquid Cri' Charge Product The following Table 3 sets forth the physical properties of the C6+ liquid product:

TABLE 3 Gravity, API 47.4 Sp. Gr. 60/60 F 0.7908 Sulfur, p.p.m. 10 Octane Number, C6+z R+3 96 R-l-O 91 C6+ PONA Analysis:

Total Parains 35.0 Total Olens 0.6 Monocycloparans 19.2 Dicycloparains 0.5 Cyclooleiins 0 Total Naphthenes 19.7 Alkylbenzenes 41.2 Indanes and Tetralins 4.7 Naphthalenes 0.9 Total Aromatics 44.8 Parain Distribution:

C7 3.8 C8 4.6 C9 10.2 C10 4.9 C11 0 C12 0 Aromatic Distribution:

C6 2.1 C7 10.4 Cs 14.9 C9 9.8 C10 2.4 C11 1.1 C12 0.4 Combined Hydrogen'` Molecular Weight:

Paraffins 107.2 Aromatics .4 Dicycloparains 1 13.8 C6+ Total 107.0

The following Table 4 sets forth the compound distri- TABLE 4 [Reaction I Arabian Naphtha (C0 330 F.) over 65% NiHZSM-5 35% A1203] i ion in the C51 liquid product (hours) 1.5 1.5

but

Time Ori-stream 0.1... Wm .om L 0. LL2.0.0. L 80005 Vol percent charge in li ht `uited twas con- K Exam- 111e` 1 and the other was contacted withstandard com- 65 mercialhydrocracking catalyst.^Tl1e data for these runs v Conventional 500001.9000050701099722816mm1n10m 0.1 3. .m 1.v 0. 0.0.1..00000090009 s. .........0.nu..0-. 00 w .6 .1 0 011000.06.1 01

3907.090000010401099722813MBHJJJ 0.0. 2. .Rm L 0. 0.0.1.0.0.0.0&0.90009.

A chargestock of a Cfr-3 80 F. fract 60 Arabian crude was split into equal al odws. 2.4. 6. L 0. 0110.00.05. .00.0.0.0 11 o.

Wt..per cent of charge cent of productl 1. 3. 0. l. ik 0. 0

38080240000206.01090722815m9lJJJ 0.0. 2. 3.3. .u L 01.100000 .90000 u 3 11. .nU ..1

Wt. per- TABLE 6-Cont1nued EXAMPLES Y2 AND 3` Hydrogen/hydroearbdfi-1.121010 ratio I .300602900005070109062281.0@01115 .0.0.0.0.0. 01 w nu 1 0 0110000601 1 .TABLE 7.OPERATING CQNDITIONS l ..........6..0.a0.0 00 m 5 1 0 0010000 01 l Total.

. .L .0.0. .6. 30.0.09 00 mu 6 1 0 0 10 0 eracked under conditions set forth below designed s to produce the vbest product mix; One -al tacted with a NZSM-5 catalyst as described (I0-C10 (naphthenes) Cv (aromatics) C10-C11 (Isoparailns) Temperature, F'

V. S H L is set forth in the following Table 7 300507300007080W0907218W30611HJ6 0.1L L 3.4 G. .L .1.L0.0.nw .om 90000 311. 0 0

.7. 390506300003040W080622830821J7 0.0. 2. 3A 0 L 0.LL00.0. .6. 90009 TABLE 5 1. .1.1L .0. .6. 0.0.nm00m 01 MP. 6 1 0 0 00 0 1 290004800002060%0896228%2011117 .0.L00.0. .6. 0000.9 00 No. 6 1 O 0 0 1 32090360000305008952184205M36 .2 00.11.00.000 a 18. 01 .nu .b1 0 1 0. 0. 0.00

54m503100002030w07931121804.12%7 0. .L .0. L0.5. 8.00. .6 020% M 7 1 0 0 0 0 1603060000.1010mu1oo3457F/1QM93WW3 ..............0. 00 n 7 7 5 chargel TABLE 6 [Conversions of weight percent product to weight and volume percent .2.2.6.L .0.4m 0 mw 0 d. 500003351001 1 0 1.

Table 5 shows the selectivities for these wing The follo runs (hours) Selectivit Wt./wt.

CFE

C1IC2- C2"Cs" C3, ISO-C4, X1C4 Ca, ISO-C4, ISO- The following Table 6 indicates the conversions and net changes of composition of the charge as compared to the product:

C1 (lsopar CT (Nephthenes) Examples 2 and 3 were repeated using Nigerian crude as the source. All operation conditions were the same except for the operating temperature which was 650 F. The following Table 9 sets forth the composition and properties of charge and product.

TABLE 9 ZSM- Conventional Component Charge treated hydrotreated Weight percent:

HL -1. 2 -1. 1 0. 2 0. 4 1. 0. 7 22. 7 6. 2 8. 6 12. 2 l0. 4. 8 5. 5 9. 3 3. 1 2. 3 49. 7 65. 5 58. 2 77. 1 77 4 94. 1

EXAMPLES 6, 7 AND 8 This series of Examples was run similarly to those of Examples 2 and 3 with a C5-360o F. virgin light Arabian naphtha feed. The aliquots contacted with ZSM-S were treated respectively at 596 F. and 642 F. The pressure was 400 p.s.i.g.; the LHSV was 2.5 and the hydrogen to hydrocarbon ratio was 2. The aliquot treated with conventional hydro-treating catalyst was treated at 700 F. at an LHSV of 1.2 and the same pressure and hydrogen to hydrocarbon ratio. The following Table l0 shows the proportion of components of feed and products.

TABLE ZSM-5 ZSM- Converb Component Charge (1) (2) tional Weight percent:

The feed to the process of this invention has been stated to be virgin gasoline boiling range material. It is intended that such feed definition encompass not only fuel range gasoline fraction, i.e. C5 to 400 F. naphtha, but also lesser range and partial range material, e.g. C6 to 360 F. or even narrower boiling range material in any portion of the full range.

What is claimed is:

1. A process comprising contacting a gasoline boiling range virgin naphtha with a catalyst consisting essentially of ZSM-S type of alumino-silicate zeolite having a hydrogenation/dehydrogenation component therein in admixture with added hydrogen in a hydrogen to hydrocarbon ratio of about 1 to 10, at about y600 to 800 F., 50 to 1000 p.s.i.g. and 0.5 to l0 WHSV, under such combination of conditions as to hydrocrack at least about 40 wt. percent of said virgin naphtha to pentane and lighter products having a C3 to C4 ratio of about 1.0 to 1.4, and an n-C4 to i-C4 ratio of about 0.85-1.2; which process also produces up to about 60 wt. percent of a C6+ liquid product having a minimum clear research octane number of about 80, which liquid product has an octane number of at least about 40 units higher than said feed.

2. A process as claimed in claim 1 wherein such combination of conditions is such as to produce a liquid product having a benzene content of less than about 5% by weight.

3. A process as claimed in claim 1 wherein said zeolite is ZSM-S.

4. A process as claimed in claim 1 wherein said hydrogenation/dehydrogenation component is a member selected from the group consisting of nickel, palladium, platinum, ruthenium, rhenium, cobalt, zinc and mixtures thereof.

5. A process as claimed in claim 4 including reforming said C6+ liquid product.

6. A process as claimed in claim 1 including pyrolyzing said pentane and lighter gas product to a pyrolysis product comprising predominantly gaseous olens, hydrogen and a gasoline boiling range liquid.

7. A process as claimed in claim 6 including recycling at least a portion of the hydrogen produced in said pyrolysis to said hydrocracking, and admixing the liquid product from said pyrolysis with the liquid product of said hydrocracking.

8. A process as claimed in claim 1 including resolving said gas product to a Cl-Cz fraction, an iso-C4 fraction and a remaining C3-C5 fraction.

9. A process as claimed in claim 8 including liquifying said C3-C5 fraction.

10. A process as claimed in claim 1 in which LPG is recovered.

References Cited UNITED STATES PATENTS 3,748,251 7/ 1973 Demmel et al. 20S-7.4 3,758,403 9/ 1973 Rosinski et al 208-1 ll 3,702,886 11/1972 Argauer et al 208-111 3,409,540 ll/1958 Gould et al 208-60 3,497,448 2/ 1970 Hamner et al 208-60 3,758,628 9/ 1973 Strickland et al 208-60 3,579,434 5/1971 Smith et al. 208-11 3,729,409 4/ 1973 Chen 208-135 3,700,585 10/ 1972 Chen et al 208-111 DELBERT E. GANTZ, Primary Examiner I. W. HELLWEGE, Assistant Examiner U.S. Cl. X.R.

m30 Umm) STATES PATENT OFFICE CERTIFICATE OF CORRECTION mm no. 3,893,510 md october 22, 19711 invented.) ROGER A. MORRISON and JOHN J. WISE It ie certified thet error appeere in the above-identified petent 'end that seid Lettere Petent ere hereby corrected as sho'wn below:

Column l, line 26 "mode" should be more-- Column l, line 50 "sep" should be "Separated-- Column 11 TABLE L Column Headings Left Right should Side Side Reads Be cl 212.6 l" 0.3" "0.2-- Tsd-chL 1.5 "15.3" 415.2--

C Ill-302" "13,6

Iso-c5 193.9 "6.5" 6.6-- 2,3-DM-cL 193.9 0,9" 0.9--

Sgned and sealed this 14th day of January T975.

(SEAL) Attest:

MecoY 151. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents .J

Claims (1)

1. A PROCESS COMPRISING CONTACTING A GASOLINE BOILING RANGE VIRGIN NAPHTHA WITH A CATALYST CONSISTING ESSENTIALLY OF ZSM-5 TYPE OF ALUMINO-SILICA ZEOLITE HAVING A HYDROGENATION/DEHYDROGENATION COMPONENT THEREIN IN ADMIXTURE WITH ADDED HYDROGEN IN A HYDROGEN TO HYDROCARBON RATIO OF ABOUT 1 TO 10, AT ABOUT 600 TO 800*F., 50 TO 1000 P.S.I.G. AND 0.5 TO 10 WHSV, UNDER SUCH COMBINATION OF CONDITIONS AS TO HYDROCRACK AT LEAST ABOUT 40 WT. PERCENT OF SAID VIRGIN NAPHTHA TO PENTANE AND LIGHTER PRODUCTS HAVING A C3 TO C4 RATIO OF ABOUT 1.0 TO 1.4, AND AN N-C4 TO I-C4 RATIO OF ABOUT 0.85-1.2; WHICH PROCESS ALSO PRODUCES UP TO ABOUT 60 WT. PERCENT OF A C6+ LIQUID PRODUCT HAVING A MINIMUM CLEAR RESEARCH OCTANE NUMBER OF ABOUT 80, WHICH LIQUID PRODUCT HAS AN OCTANE NUMBER OF AT LEAST ABOUT 40 UNITS HIGHER THAN SAID FEED.

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