CA1243335A - Oligomerization of liquid olefin over a nickel- containing silicaceous crystalline molecular sieve - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process for oligomerizing olefins in the liquid phase using nickel-containing silicaceous crystalline molecular sieve catalyst.

Description

333~

OLIGOMERIZATION OF LIQUID OLEFIN OVER
A NICKEL-CONTAINING SILICACEOUS
CRYSTALLINE MOLECULAR SIEVE

BACKGROUND OF THE INVEN~ION
1. Field of Invention The present invention is in the field of olefin oligomerization. More specifically, the present invention relates to oligomerizatlon of olefins in the liquid phase with a nickel-containing silicaceous crystalline molecular sieve ca~alyst.

2. escription of the Prior Art Oligomerization and polymerization of olefins in the gas phase over various zeolites is known in the art.
For example, ~.S. Patent Mo. 3,960,978 a process for producing a gasoline fraction containing predominantly olefinic compounds which comprises contacting a C2 to C5 ~0 olefin with a ZSM-5 type crystalline aluminosilicate zeolite at a temperature of from about 500F to about 900F is disclosed.
U~S. Patent No. 4,021,502 describes the conversion of gaseous C2 to C5 olefins into gasoline blending stock by passage over ZSM-12 at temperatures of from about ~00F to about 1200F.
U.S. Patent Mo. 4,211,640 discloses a process for the treatment of highly olefinic gasoline containing at least about 50% by weight of olefins by contacting_said oleEinic gasoline with crystalline aluminosilicate zeolites, such as those of the ZSM-5 type, so as to selectively react olefins other than ethylene and produce both gasoline and fuel oil.
U.S. Patent Mo. 4,254,295 discloses a process for the oligomerization of olefins by con~acting said oleEins in the liquid phase with ZSM-12 catalyst at temperatures of 80F to 400F.
U.S. Patent No. 4,227 r 992 discloses a process for separati~g ethylene in admixture with light olefins by contacting said olefinic mixture with a ZSM-5 catalyst and thus producing both gasoline and fuel oil range materials.

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The processes disclosed in these patents differ from that of the present invention in tha-t -they employ either a different catalyst, higher tempera-tures, or reaction in the gaseous phase.
Also, an important feature of several of -the catalysts used in these prior art processes is -that the catalyst must have reduced ac-tivi-ty before oligomeriza-tion. Such catalyst of re-duced activity may be obtained by steaming or by use in a previous conversion process.
This deactivation step is not required in the process of -the presen-t invention.
SUM~RY O~ THE INVENTION
In accordance wi-th the present invention, there has been discovered a process for oligomerizing alkenes comprising:
(a) contacting a C2 to C20 olefin or mix-ture thereof in -the liquid phase wi-th a nickel-containing silicaceous crys-talline molecular sieve in the hydrogen Eorm selected from the group consis-ting of HZSM-5, HZSM-ll, crystalline admixtures of HZSM-5 and HZSM-ll, silicalite, "an RE 29,948 organosilicate" (as defined below), and CZM (as defined below) or mix-tures -thereof, a-t a -temperature Erom abou-t ~5F -to about ~50F; (b) recovering an effluent comprising oligomerized alkene.
I-t has been found tha-t the presen-t process provides selective conversion o:E -the olefin Eeed -to oligomer products.
The present process effec-ts the conversion of the olefin feed to dimer, -trimer, -tetramer, etc., product:s with high selectivity.
The product of -the present reaction thus contains primarily olefin oligomer and li-ttle or no light cracked products, paraf~
fins, etc.
The high selectivi-t~ is in part due -to the surprising-ly high oligomerization ac-tivi-ty of the catalys-t of the present ,J

~33~; 61936-16'18 -2a-process, which permits high conversion at low temperatures where cracking reactions are minimized.
The oligomers which are the products of the process of this invention are medium to heavy olefins which are highly useful for both fuels and chemicals. These include olefinic gasoline, such as from propylene ~2~333~i 01 _3_ dimerization, and extremely high quality midbarrel fuels, such as jet fuel~ Higher molecular weight compounds can be used without further reaction as components of functional fluids such as lubricants, as viscosity index improvers in lubricants, as hydraulic fluids, as transmission fluids, and as insulating oils, e.g., in transformers to replace PCB containing oils. These olefins can also undergo chemical reactions to produce surfactants which in turn can be used as additives to improve the operating characteristics of the compositions to which they are added (e.g., lubricating oils) or can be used as primary surfactants in highly important activities such as enhanced oil recovery or as detergents. Among the most used surfactants prepared from the heavy olefins are alkyl sulfonates and alkyl aryl sulfonates.
~ significant feature of the present process is the liquid phase contacting of the olefin feed and the ~o nickel-containing silicaceous crystalline molecular sieves. There will be appreciated that the pressures and temperatures employed must be sufficient to maintain the system in the liquid phase. As is known to those in the art, the pressure will be a function of the number of carbon atoms of the feed olefin and the temperature.
The oligomerization process described herein may be carried out as a batch type, semi-continuous or continuous operation utilizing a fixed or moving bed catalyst system.

3~ BRIEF DESCRIPTION OF THE DRAWINGS
.
Figure 1 is a graph showing the conversion of propylene to higher molecular weight products as a function oE time at 130F, 1600 psig and 0.5 LEISV for two different catalysts.
Figure 2 is a graph showing the carbon number selectivity for oligomeri~ing propylene at 130F, 1600 psig and 0.5 LHSV for two different catal~sts.
Eigure 3 i5 a graph showing a plot o~
temperature for 90% conversion of propylene to C5~ over ~3335 Ol -4_ Ni-Zn-HZSM-5 catalyst versus time under the conditions shown.
05 ~igure 4 is a graph showing a plot of temperature for 70% conversion of C6~Cg gasoline feed to higher boiling product versus time over Ni-Zn-HZSM-5 and Zn-HZSM-5 catalysts under the conditions shown.
Figure 5 is a gas chromatogram of the product of Example 19.
Figure 6 is a graph showing a plot of temperature for 70% conversion of C6-Cg gasoline feed to higher boiling product versus time over Ni-Zn-HZSM-5 under the conditions shown.
DESCRIPTION OF SPEC~FIC EMBODIMENTS
The feeds used in the process of the invention contain alkenes which are liquids under the conditions in the oligomerization reaction zone. Under standard operating procedures it is normal both to know the chemical composition of feedstocks being introduced into a reaction zone and to set and control the temperature and pressure in the reaction zone. Once the chemical composi-tion of a feedstock is known, the temperature and hydrocarbon partial pressures which will maintain all or part of the feed as li~uids can be determined using standard tables or routine calculations. Conversely, once the desired temperature and pressure to be used in the reaction zone are set, it becomes a matter of routine to determine what feeds and feed components would or would not be liquids in the reactor. These calculations involve using critical temperatures and pressures. Critical temperatures and pressures for pure organic compounds can be found in standard reference works such as CRC Handb ok of ChemistrY and Physlcs, International Critical Tables, 3S Handbook of Tables _or Applied Engineerin9 Science, and Kudchaker, Alani, and Zwolinski, Chemical Reviews 6~, 659 (1968), The critica:L tem~erature for a pure compound is that temperature above which the com~ound cannot be li~ue~ied regardless of pressure. ~he cri~ical pressure is the `?.~

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01 _5_ vapor pressure of the pure compound at its critical temperature. These points for several pure alkenes are S listed below:

Tc C (F) Pc-at~ (bar) ethene ~.21 (43.6) 49.66 (50.3) propene 91.3 (197.2) 45.6 (46.2) l-butene 146.4 (295.5) 39.7 (40.2) l-pentene 191.59 (376.9) 40 ~40.5) iso-2-pentene 203 (39~) 36 (36.5) l-hexene 230.83 (~47.49) 30.8 (31.2) l-heptene 264.08 (507.34) 27.8 (28.2) 1-octene 293.4 (560~1) 25.6 ~25.9) l-decene 342 (648) 22.4 (22.7) It can be appreciated that at temperatures above about ~U 205C (401F), pure C5 and lower alkenes must be gaseous, while pure C6 and higher alkenes can still be liquefied by applying pressure. Slmilarly, above about 275C (527F) pure C8 and higher alkenes can be maintained in the liquid state, while pure C7 and lower alkenes must be gaseous.
Typical feeds are mixtures of compounds. But even so, once the chemical composition of the feed is known, the critical temperature and pressure of the mix-ture can be determined from the ratios of the chemicals and the critical points of the pure compounds. See for example, the methods of Kay and Edmister in Perr~~
Chemical Engineers Handbook, 4th Edition, pages 3-214, 3-215 (McGraw Hill, 1963).

Of course, the only constraint on the alkenes present in the feed and which are to react in the oligo-merization reaction zone is that these alkenes be liquids under the conditions in the reaction zone (the conditions include a temperature of less than about 450F). The chemical composition of the alkenes can be varied to obtain any desired reaction mixture or product mix, 50 ": :`,``

33;~5 long as at least some of the alkene components of the ~eed are liquid.
05 The alkene chains can be branched~ And, even though the nickel-containing silicaceous crystalline molecular sieve catalysts used in this invention are intermediate pore size molecular sieves, alkenes having quaternary carbons (two branches on the same carbon atom) can be used. But where quaternary carbons are present, it is preferred that the branches are methyl.
The preferred alkenes are straight chain, or n-alkenes, and the preferred n-alkenes are l-alkenes. The alkenes have from 2 to 20 carbon atoms, and more prefer-ably have from about 2 to about 6 carbon atoms.
One of the surprising discoveries of thisinvention is that under certain reaction conditions, longer chain alkenes can be polymerized instead of being cracked to short chain compounds. Additionally, the oligomers produced from long n-l-alkenes are very highly desirable for use as lubricants. The oligomers have surprisingly little branching so they have very high viscosity indices, yet they have enough branching to have very low pour points.
The feed alkenes can be prepared from any source by standard methods. Sources of such olefins can include FCC offgas, coker offgas, synyas (by use of CO reduction catalysts), low pressure, nonhydrogenative zeolite dewaxing, alkanols (using high silica zeolites), and dewaxing with crystalline silica polymorphs. Highly suitable n-l-alkene feeds, especially for preparing lubricating oil basestocks, can be obtained by thermal cracking of hydrocarbonaceous compositions which contain normal paraffins or by Ziegler polymerization of ethene.
Often, suitable feeds are prepared from lower alkenes which themselves are polymerized. Such feeds include polymer gasoline from bulk H3PO4 polymerization, and propylene dimer, and other olefinic polymers in the C~-C20 range prepared by processes known to the art.

L33;~5 01 _7_ The nickel-containing silicaceo~s crystalline molecular sieves used in this invention are of S intermediate pore size. By "intermediate pore size", as used herein, is meant an effective pore aperture in the range of about 5 to 6.5 Angstroms when the molecular sieve is in the H-form. Molecular sieves having pore apertures in this range tend to have unique molecular sieving characteristics. Unlike small pore zeolites such as erionite and chabazite, they will allow hydrocarbons having some branching into the molecular sieve void spaces. Unlike larger pore zeolites such as the faujasites and mordenites, they can differentiate between n-alkanes and slightly branched alkanes on the one hand and larger branched alkanes having, for example, quaternary carbon atoms.
The effective pore size of the molecular sieves can be measured using standard adsorption techniques and hydrocarbonaceous compounds of known minimum kinetic diameters. See Breck, Zeolite Molecular Sieves, 1974 (especially Chapter 8) and Anderson et al, J. Catalysis _ , 114 (1979).

Intermediate pore size molecular sieves in the H-form will typically admit molecules having kinetic diameters of 5.0 to 6.5 Angstroms with little hindrance.
Examples of such compounds (and their kinetic diameters in Angstroms) are: n-hexane (~.3), 3-methylpentane (5.5), benzene (5.85), and toluene (5.~). Compounds having kinetic diameters of about 6 to 6.5 Angstroms can be admitted into the pores, depending on the particular sieve, but do not penetrate as quickly and in some cases are effectively excluded. Compounds having kinetic diameters in the range of 6 to 6.5 Angstroms irlclude:
cyclohexane (6.0), 2,3-dimethylbutane (6.1), m-xylene (6.1), and 1,2,3,4 tetramethylbenzene (6.4). Generally, compounds having kinetic diameters of greater than about 6.5 Angstroms do not penetrate the pore apertures and thus are not absorbed into the interior of the molecular sieve lattice. Examples of such larger compounds include: o-xylene (6.8), hexamethylbenzene (7.1), 1,3,5-trimethylbenzene (7.5), and tributylamine (8.1).
The preferred effective pore size range is from about 5.3 to about 6.2 Angstroms.
In performing adsorption measurements to determine pore size, standard techniques are used. It is convenient to consider a particular molecule as excluded if it does not reach at least 95% of its equilibrium adsorption value on the zeolite in less than about 10 minutes (p/po=0.5: 25C).
Nickel-containing HZSM-5 is described in United States Patent Nos. 3,702,8~6 R.J. Argauer, et al, November 14, 1972 and 3,770,614 Graven, November 6, 1973.
HZSM-ll is described in United States 3,709,979 Chee, January 9, 1973. "Crystalline admixtures" of ZSM-5 and ZSM-ll also exist, which arethought to be the result of faults occurring within the crystal or crystallite area during the synthesis of the zeolites. The "Crystalline admixtures" are themselves zeolites but have characteristics in common, in a uniform or nonuniform manner, to what the literature reports as distinct zeolites. Examples of crystalline admixtures of ZSM-5 and ZSM-ll are disclosed and claimed in United States

4,229,424 Kokotailo, October 21, 1980. The crystalline admix~ures are themselves intermediate pore size zeolites and are not to be confused with physical admixtures of zeolites in which distinct crystal or crystallites of different zeolites are physically present in the same catalyst composite or hydro-thermal reaction mixture.
Silicalite is disclosed i~ United States 4,061,724 Flanegen, et al, December 6, 1977; the "RE 29,948 organo-61936-16~8 8a-~333~
silica-tes" are diselosed in U.S. Reissue Pa-tent RE 29,948 Dwyerl et al March 27/ 1979; chromia silicates, CZM, are disclosed in Canadian Paten-t No. 1,165,312, filed August 22, 1980. In this pa-tent, this class of chromia silicates are defined as follows in claim 1 and 2:
1. A crystalline chromia silica-te having a mol ratio of oxides of SiO2:Cr2O3 of greater than about 20:1 ancd having the followincJ random powder X-ray diffraction pattern:

Interplanar Spaeing, d-A Relative Intensity 11.1 + 0.2 v.s.
10.0 + 0.2 v.s.
3.85 + 0.07 v.s.
3.82 ~ 0.07 s.
3.76 + 0.05 s.
3.72 + 0.05 s.

2. A erystalline chromia silicate composition expressed in the anhydrous state in terms of mols of oxides comprising:
R2O:aM2O:bcr2o3:csio2 wherein R2O is a quaternary alkylammonium oxide, M is an alkali metal selected ~rom the group of alkali metals consisting of lithium, soclium, po-tassium or mixtures thereof, a is gLeater than O but less than 1.5, c is grea-ter -than or equal -to 12, and c/b is grea-ter than 20; and said chromia silicate having the EollowincJ random powder X-ray diffraetion pattern:
Interplanar Spacing, d-A Relative Inte sity __ _ _ 11.1 ~ 0.2 v.s~
10.0 -~ 0.2 v.s.

3.85 ~ 0.07 v.s.

r--~
.~

-8b-~2~33~
3.82 + 0.07 s.
3.76 + 0.05 s.
3.72 + O.OS s.
The reader is referred to the full text of this patent for further information.
The so-called "RE 29,948 organosilicates" are defined in both this United States Reissue Paten-t, and its parent United S-tates Patent 3,941,871 Dwyer, et al, March 2, 1976 as follows:

61~36-1648 _g_ 33~
"A crystal metal organosilicate having a composition, in i-ts anhydrous state, in terms of mol ratios of oxides, as follows:
0.9 ~ 0-2 [xR2O + (l-x)M2 O]: ~0.005 A12O3:~ lSio2 where M is sodium, or sodium in combination with tin, calcium, nickel or zinc, R is a tetraalkylammonium, and x is a number greater than zero but not exceeding 1, said organosilicate having the X-ray diffraction lines se-t forthinTable 1 of the specification."
Table 1 includes some 16 lines for various inter~
planar spacings. The four main ones appear to be a very strong line for a spacing of 3.85 _ 0.07A, and strong lines a~ 3.71 + 0.05A, 10.0 + 0.2A, and 11.1 + 0.2A. The reader is referred to the full text of these patents for further information.
The crystalline silica polymorphs, silicalite, and "RE 29,~48 organosilicates", and the chromia silicate, CZM, are essentially alumina free.
"Essentially alumina free", as used herein, is meant the product silica polymorph (or essentially alumina-free silicaceous crystalline molecular sieve) has a silica:alumina mol ratio of greater than 200:1, preferably greater than 500:1. The term "essen-tia]ly alumina free" is used because i-t is difficult to prepare completely aluminum free reaction mixtures for synthesizing -these materials. Especially when commercial silica sources are used, aluminum is almost always present to a greater or lesser degree. The hydro-thermal reaction mixtures from which the essen-tially alumina free crystalline silicaceous molecular sieves are prepared can also be referred -to as being substantially aluminum free. By this usage is meant tha-t no aluminum is inten-tionally added 61936-16~8 -9a- ~243335 to the reaction mixture, e.g., as an alumina or aluminate reagent, and that to the extent aluminum is present, it occurs only as a contaminant in the reagent.
The most preferred molecular sieve is the zeolite Ni-HZSM-5 and Ni containing hydrogen form of 33~

~1 -10-silicalite. Of course, these and the other molecular sieves can be used in physical admixtures.
When synthesized in the alkali metal form, the zeolites may be conveniently converted to -the hydrogen form by well known ion exchange reactions, for example, by intermediate formation of the ammonium form as a result of ammonium ion exchange and calcination of the ammonium form to yield the hydrogen form, as disclosed in U.S. Patent No. 4,211,640, or by treatment with an acid such as hydrochloric acid as disclosed in U.S. Patent No.
3,702,886.
Nickel is incorporated into these silicaceous crystalline molecular sieves according to techniques well known in the ar~ such as impregnation and cation exchange.
For ~xample, typical ion exchange techniques would be tG
contact the hydrogen form of the particular sieve with an aqueous solution of a nickel salt~ ~lthough a wide ~ variety of salts can be employed, particular preference is given to chlorides, nitrates and sulfates. The amount of nickel in the zeolites range from 0.5% to 10% by weight and preferably from 1% to 5% by weight.
Representative ion exchange techniques are ~5 disclosed in a wide variety of patents including U,S. Patent Nos. 3,140,249; 3,140,251; 3,960,978 and 3,140,253.
Following contact with the salt solution, the zeolites are preferably washed with water and dried at a 3~ temperature ranging from 150F to about 500F and thereafter heated in air at temperatures ranging from about 500F to 1000F for periods of time ranging from 1 to 48 hours or more~
The nickel-containing silicaceous crystalline molecular sieve catalysts can be made substantially more stable for oligomerization by including from about 0.2% to 3~ by weight and preferably 0.5% to 2~ by weight of the Group IIB metals, zinc or cadmium and preferably zinc. A
primary characteristic of these substituents is that they 4~ are weak bases, and are not easily reduced. These metals ~33~

can be incorporated into the catalysts using standard impregnation, ion exchange, etc., techniques. Strongly 0~ basic metals such as the alkali metals are unsatisfactory as they poison substantially all of the polymerization sites on the zeolite. For this reason, the alkali metal content of the zeolite is less than 1~, preferably less than 0.1~, and most preferably less than 0.01%. The feed should be low in water, i.e., less than 100 ppm, more preferably less than 10 ppm, in sulfur, i.e., less than 100 ppm and preferably less than 10 ppm, in diolefins, i.e., less than 0.5%, preferably less than 0.05% and most preferably less than 0.01%, and especially in nitrogen, i.e., less than 5 ppm, preferably less than 1 ppm and most preferably less than 0.~ ppm.
The polymerization processes of the present invention are surprisingly more efficient with small crys-tallite sieve particles than with larger c-rystalline particles. Preferably, the molecular sieve crystals or crystallites are less than about 10 microns, more preferably less than about 1 micron, and mos-t preferably less than about 0.1 micron in the largest dimension.
Methods for making molecular sieve crystals in different physical size ranges are known to the art.
The molecular sieves can be composited with inorganic matrix materials, or they can be used with an organic binder. It is preferred to use an inorganic matrix since the molecul~r sieves, because of their large internal pore volumes, tend to be fragile, and to be subject to physical collapse and attrition during normal loading and unloading of the reaction zones as well as during the oligomerization processes. Where an inorganic matrix is used, it is highly preferred that the matrix be substantially free of hydrocarbon conversion activity. It can be appreciated that if an inorganic matrix having hydrogen transfer activity is used, a significant portion of the oligomers which are produced by the molecular sieve may be converted to paraffins and aromatics and to a large ~o degree the benefits of my invention ~ill be lost.

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~1 -12-The reaction conditions under which the oligomerization reactions take place include hydrocarbon 05 partial pressures sufficient to maintain the desired alkene reactants in the liquid state in the reaction zone.
Of course, the larger the alkene molecules, the lower the pressure required to maintain the liquid state at a given temperature. As described above, the operating pressure is intimately related to the chemical composition of the feed, but can be readily determined. Thus, the required hydrocarbon partial pressure can range from 31 bar at 450F for a pure n-l-hexene feed to about atmospheric pressure for a n-1-C15-C20 alkene mixture. In the process of this invention, both reactant and product are liquids under the conditions in the reaction zone, thus leading to a relativel~ high residence time of each molecule in the catalyst.
The reaction zone is typically operated below about 450F. Above that temperature not only significant cracking o~ reactants and loss of oligomer product take place, but also significant hydrogen transer reactions causing loss of olefinic oligomers to paraffins and aromatics take place. An oligomerization temperature in the range from about 90F to 350F is preferred. Liquid hourly space velocities can range from 0.05 to 20, preferably from 0.1 to about 4.
Once the effluent from the oligomerization reaction ~one is recovered, a number of further processing steps can be perormed.
If it is desired to use the long chain compounds which have been formed in middle distillate fuel such as jet or diesel or in lube oils as base stock, -the alkene oligomers are preferably hydrogenated.
All or part of the effluent can be contacted with the molecular sieve catalyst in further reaction zones to further react unreacted alkenes and alkene oligo-mers with themselves and each other to form still longer chain materials. Of course, the longer the carbon chain, the more susceptible the compound is to bein~3 cracked.

~l -13-Therefore, where successive oligomerization zones are used, the conditions in each zone must not be so severe as 05 to crack the oligomers. Operating with oligomerization zones in series can also make process control of the exothermic oligomerization reactions much easier.
One particularly desirable method of operation is to separate unreacted alkenes present in the effluent from the alkene oligomers present in the effluent and then to recycle the unreacted alkenes back into the feed.
The following examples further illustrate this invention.
EXAMPLES
lS Example l HZSM-5 zeolite of 80 SiO2/Al~O3 mole ratio was mixed with peptized Catapal alumina at a 50/50 sieve/alumina weight ratio, extruded through a 1/16" die, dried overnight at 300F under N2, then calcined in air ~0 for 8 hours at 850F. The catalyst was exchanged ~ive times with a 1% aqueous ammonium acetate solution, then washed with water to give a final Na level of 100 ppm.

The catalyst of Example l was impregnated by the pore fill method with 1% Zn using an aqueous solution of zinc nitrate, then dried and calcined as in Example l.
Exam~le 3 The catalyst of Example l was exchanged with a 1% aqueous nickel acetate solution at 180F for five hours, washed with water, then dried and calcined as in Example l. The Ni content of the calcined catalyst was 3 wt %.
_ ample 4 The catalyst of Example 3 was impregnated with 1% Zn, dried, and calcined as in Example l.
Example 5 The catalyst of Example 2 (Zn-HZSM-5) was tested for conversion of propylene to higher molecular weight products at 130F, 1600 psig, and 0.5 LHSV. At 40 hours 33~

on stream, conversion to C5+ was less than 20 wt %
(Figure 1), with 32 wt % selectivity to dimer (Figure 2).
The propylene dimer distribution is given in Table I.

TABLE I

10 C6 Olefin Composition From Propylene Oligomerization C6 Olefin Selectivity 4-m-2-C5= 14.6 3-, 4-m-1-C5= 9.4 2-~-2-C5= 32.2 2-m-1-C5= ~.3 3-m-2-C5= 10.4 n-C6= 0.8 2,3-dm-C4= 28.3 Example 6 The catalyst of Rxample 4 (Ni-Zn-HZSM-5) was tested for propylene conversion at the same conditions as in Example 5. At 40 hours on stream, conversion to C5~
was over 98 wt % (Figure 1), with selectivity to dimer at 71 wt % (Figure 2). This shows the surprising benefit of Ni addition to HZSM-5 in terms of both activity and selectivity to dimer. The propylene dimer distribution is given in Table II.

3~i TABLE II

~5 C6 Olefin Composition From Propylene Oligomerization C6 Olefin Selectivity '~
4-m-2-C5= 50.7 3-, 4-m-1-C5= 6.1 2-m-~-C5= 8.7 2-m-1-C5= 1.2 3-m-2-C5= 0.2 n-C6= 26.8 2,3-dm-C4= 6.3 For comparison, a 5% Ni on amorphous SiO2-A12O3 was prepared by pore-fill impregnation of a 40/60 SiO2-A12O3 cogel with an aqueous nickel acetate solution, drying at 300F overnight, then calcining in air for eight hours at 850F. When tested for propylene conversion at the conditions of Example 5, conversion to C5-~ at 40 hours on stream was 54 wt ~, with 40 wt ~ selectivity to dimer~
Example 8 The catalyst of Example 3 (~ IZSM-5) was tested for propylene conversion at 1600 psig and 1.0 LHSV. At 200 hours on stream, conversion to c5-t was 73 wt ~ at 120F.
~,2~
The catalyst o Example 2 (Zn-llZSM-5) was tested for propylene conversion at 0 psig, 550E`, and 2 LHSV
under olefin gas phase conditions. After 90 hours on streamr conversion to C5+ was 80 wt %.
Example 10 3 The catalyst of Example 3 (Ni-HZSM-5) was tested for propylene conversion at the same conditions as in Example 9. At 70 hours on stream, conversion to C5~ was 30 wt ~. This shows that the addition of Ni to HZ~M-5 is only beneficial when oligomerization is carried out under substantially liquid phase conditions.

~333~

Example 11 The catalyst of Example 4 (Ni-Zn-ElZSM-5) was 05 tested for propylene conversion at 0.5 LHSV and 1600 psig.
A plot of catalyst temperature for 90~ conversion to C5-~
versus time on stream is shown in Figure 3. At 430 hours on stream, the reactor pressure was reduced to 800 psig.
The catalyst operated 800 hours before requiring a temperature of 180F for 90% conversion to C5~. Product inspections are shown in Table III~

TABLE III

C ~ Product Inspections from Oligomerizing

5 Propylene at 1000 psig and 0.5 LHSV

Temperature F 120 Conversion to C5+, wt % 85 Gravity, ~PI 74O0 Research Octane No., clear 94.0 Simulated TBP Distillation LV ~, F

70/go 161/2~3 Paraffins, LV% 0 Olefins, LV~ 100 Naphthenes, LV~ 0 Aromatics, LV~ 0 Examples 12-16 The catalyst of Example 1 was impregnated with transition metals known in the art to be active for promoting light olefin oligomerization. These include Co, Cu, Pd, V, and Cr. The results given in Table IV show these catalysts much less active than Ni-HZSM-5.

~0 ~2~3~3~

TABLE IV

35Conversion of Propylene to C5+ Products Over Transition Metal - HZSM-5 Catalyst at 130-150E~, 0.5 LHSV, and 1600 Psig Wt % Conversion Example Metal ~ Loadingat 40 Hrs.

10 12 Co 2.4 12 13 Cu 0.5 < 5 14 Pd 2.5 <10 V 1.6 <10 16 Cr 5 < 5

6 Ni 3 98 Example 17 The catalyst of Example 2 (Zn-HZSM-5) was tested for conversion of an olefinic C6-Cg gasoline feed (Table V) to higher boiling product. The catalyst temper-ature for 70% conversion to 350F+ as a function of time on stream at 800 psig and 0.5 LHSV is shown in Figure 4 The catalyst fouling rate at these conditions was about 0.17F/hr.

~0 ~333~;

01 ~18-TABLE V

05Inspections of C6-Cg Olefinic Gasoline Gravity, API 69.8 Research Octane Number, Clear 95.5 10 D-86 Distillation, LV%, F

Paraffins, LV% 0 15 Olefinsl LV% 99 Naphthenes, LV%
Aromatics, LV%

Example 1 ;~U
The catalyst of Example 4 (Ni-Zn-HZSM-5) was tested with the same feed as in Example 17 and at the same pressure and LHSV. At 100 hours on stream, catalyst temperature was 260F (Figure 4), about 170F lower than needed with Zn-HZSM-5. Beyond 250 hours, the fouling rate was only < 0.04F/hr, one-fourth or less than that for Zn-HZSM~5, showing the benefit of Ni addition to the catalyst with C6+ olefinic feeds. A gas chromatogram of the product is shown in Figure 5.
Example 19 The catalyst of Example 3 (Ni-HZSM-5) was tested with the same feed as in Example 17 and at the same pressure but at a higher feed rate (1 and 2 LHSV). Even at 2 LHSV~ the fouling rate was only 0.10F/hr (Figure 6), less than that for Zn-HZSM-5 at only 0.5 LHSV.
Example 20 A Zn-silicalite catalyst was prepared in the following manner. H-silicalite of 240 SiO2/A12O3 mole ratio was mixed with peptized and neutralized Ca~apal q0 alumina at a 67/33 sieve/alumina weight ratio, extruded ~3~

through a 1/16" die, dried overnight at 300F under N2, then calcined in air for 8 hours at 850F. The catalyst S was impregnated by the pore-fill method to 1 weight % Zn using an aqueous solution of Zn(NO3)~, then dried and calcined as done previously.
Example 21 The catalyst of Example 1 was impregnated to 3 weight % Ni by the pore-fill method using an aqueous solution of Ni(NO3)2.6H2O. The catalyst was dried overnight under N2 at 300F, then calcined in air for 8 hours at 850F.
Example 22 15 The Zn-silicalite catalyst of Example 1 was tested for converting propylene to higher molecular weight products at 150F, 1000 psig, and 0.5 LHSV. At 24 hours onstream, conversion to C5+ was 3.2% with 38~ selectivi~y to dimer.
~ Example 23 The Ni-Zn-silicalite catalyst of Example 2 was tested for converting propylene at the same ronditions as in Example 3. At 40 hours onstream, conversion to C5+ was 72.7% with 77% selac~ivity to dimer.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for oligomerizing alkenes comprising:
(a) contacting a C2 to C20 olefin or mixture thereof in the liquid phase with a nickel containing silicaceous crystalline molecular sieve in the hydrogen form selected from the group consisting of (i) HZSM-5, HZSM-11, crystalline admixtures of HZSM-5 and HZSM-11; and silicalite;
(ii) an organo silicate from the class known as the "RE 29,248 organosilicates" and defined as a crystal metal organosilicate having a composition, in its anhydrous state, in terms of mole ratios of oxides as follows:

0.9 + 0.2 [xR2O + (1-x)M2/nO]: <0.005 AC2O3:> 1SiO2 wherein m is sodium or sodium in combination with tin, calcium, nickel or zinc, R is a tetraalkylammonium group and x is a number greater than O but not exceeding 1, said organosilicate having four main strong X-ray diffraction lines corresponding to a spacing of 3.85 + 0.07A; 3.71 + 0.05A; 10.0 + 0.2A and 11.1 + 0.2A; and (iii) a crystalline chromia silicate, from the class known as CZM, and defined as a crystalline chromia silicate having a mol ratio of oxides of SiO2: Cr2O3 of greater than about 20:1 and having the following random powder X-ray diffraction pattern:
Interplanar Spacing, d-A Relative Intensity 11.1 + 0.2 v.s.

10.0 + 0.2 v.s.

3.85 + 0.07 v.s.

3.82 + 0.07 s.

3.76 + 0.05 s.

3.72 + 0.05 s.

and which may further contain a quarternary alkyl ammonium oxide, and an alkali metal selected from lithium, sodium, potassium or mixtures thereof;
or mixtures of said hydrogen form molecular sieves, at a temperature from about 45°F to about 450°F; and (b) recovering an effluent comprising oligomerized alkene.

2. The process of Claim 1 wherein the nickel-containing silicaceous crystalline molecular sieve also contains zinc cation.

3. The process of Claim 1 wherein said contacting is carried out at a LHSV of from about 0.2 to 5.

4. The process of Claim 1 wherein the pressure is from about 50 to about 1600 psig.

5. The process of Claim 1 wherein said nickel-containing silicaceous crystalline molecular sieve is HZSM-5.

6. The process of Claim 1 wherein said nickel-containing silicaceous crystalline molecular sieve is HZSM-11.

7. The process of Claim 1 wherein said nickel-containing silicaceous crystalline molecular sieve is a crystalline or physical admixture of HZSM-5 and HZSM-11.

8. The process of Claim 1 wherein said nickel-containing silicaceous crystalline molecular sieve is silicalite.

9. The process of Claim 1 wherein said nickel containing silicaceous crystalline molecular sieve is an "RE 29,248 organo-silicate" as defined in claim 1.

10. The process of Claim 1 wherein said nickel-containing silicaceous crystalline molecular sieve is a chromia silicate from the class known as CZM as defined in claim 1.

11. The process of Claim 1 wherein the nickel-containing silicaceous crystalline molecular sieve also contains zinc cation.

12. The process of Claim 1 wherein said alkenes comprise n-alkenes.

13. The process of Claim 11 wherein said n-alkenes are 1-alkenes.

14. The process of Claim 1 wherein said alkenes comprise branched chain alkenes and wherein the branches of said branched chain alkenes are methyl branches.

15. The process of Claim 1 further comprising the step of hydrogenating said alkene oligomers.

16. The process of Claim 1 further comprising the steps of: separating unreacted alkenes present in said effluent from alkene oligomers present in said effluent and recycling said unreacted alkenes into the feed for said contacting step.