WO1993014048A1

WO1993014048A1 - Olefin conversion process

Info

Publication number: WO1993014048A1
Application number: PCT/US1992/000370
Authority: WO
Inventors: Kathleen Marie Keville; Albin Huss, Jr.; Altaf Husain; Kenneth Joseph Del Rossi; Robert Glenn Bundens; Cynthia Ting-Wah Chu
Original assignee: Mobil Oil Corporation
Priority date: 1992-01-16
Filing date: 1992-01-16
Publication date: 1993-07-22
Also published as: AU1264392A

Abstract

Light olefins are converted to isoalkene-rich hydrocarbon products, e.g., isobutene and isoamylenes with zeolite MCM-22 catalyst.

Description

OLEFIN CONVERSION PROCESS

This invention relates to a process for converting olefins, e.g., C_-C₁₆ linear mono-alkenes to isoalkene hydrocarbon products, especially C . -C-. tertiary alkenes.

In view of the phasing out of leaded gasoline and restrictions on the aromatics content of gasoline fuels, there is a great impetus to develop processes which upgrade light olefins to high octane components. One such class of materials is aliphatic tertiary ethers, such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME) . However, the availability of isobutylene and isoa ylene feedstock for these ethers is limited. Therefore, processes for making these olefins from readily available feedstocks are sought. The process described herein is one such process and involves the conversion of readily available refinery feedstocks, such as propene and/or n-butene, to products rich in isobutylene and/or isoamylene.

The ability of shape selective zeolites such as ZSM-5 to convert propylene to C. + C₅ olefins has been recognized previously, see for example EP-A-26041.

It has now been found that a recently discovered zeolite, designated MCM-22, is an effective catalyst for converting lower olefins to isoalkenes at high selectivity.

Accordingly, the invention resides in a process for converting a lower olefin feedstock to an iso-alkene rich product by contacting the feedstock with a catalyst comprising a synthetic porous crystalline zeolite which, in its calcined form, has an x-ray diffraction pattern including the values listed in Table I below. In a first embodiment of the invention, the conversion is olefin or double bond isomerization, in which a double bond possessed by a olefinic molecule is moved from an alpha position to an internal position within the molecule. In this case the feed preferably contains n-butene and conversion is preferably effected at a temperature of 0 to 650°C, more preferably 150 to 250°C, a pressure of 100 to 14000 kPa (1 to 2000psia) and a weight hourly space velocity of 0.1 to 500.

In second embodiment, the conversion involves olefin interconversion or restructuring in which a C---C.,--, preferably a C -C,, olefin feed is converted to a product containing at least 6 wt% tertiary C and C₅ olefins. This process involves a combination of operations including cracking, polymerization or dimerization and isomerization so as to provide a product rich in tertiary olefins having a carbon number less than twice that of the starting olefin. Interconversion conditions preferably include a temperature of 250 to 700°c, preferably 300 to 450°C, a pressure of 100 to 1500 kpa, preferably 150 to 500 kpa and an LHSV of 0.1 to 100, preferably 0.2 to 20.

Preferably, the zeolite catalyst (described in detail below) has an acid activity (alpha value) of 1 to 150, more preferably less than 50, and most preferably less than 10. Many olefins are suitable for use as the feedstock in the interconversion process of the second embodiment _r especially linear monoalkenes having 3 to 16 carbon atoms. Suitable olefinic feedstocks can be obtained from a variety of sources including fossil fuel processing streams such as gas separation units, the cracking of C_ hydrocarbons, coal by-products, and various synthetic fuel processing streams. The cracking of ethane and the conversion of the effluent is disclosed in U.S. Patent No. 4,100,218 and conversion of ethane to aromatics over Ga-ZSM-5 is disclosed in U.S. Patent No. 4,350,835. Olefinic effluent from the fluidized catalytic cracking of gas oil, and the like, is a valuable source of olefins, mainly C,-C. olefins, suitable for conversion according to the present olefin interconversion process. Olefinic refinery streams can be advantageously converted to valuable higher hydrocarbons employing the catalytic interconversion process of this invention. One such stream which is advantageously employed as feed herein is an FCC light olefin stream possessing the following typical composition. Wt.%

Ethane 3.3

Ethylene 0.7

Propane 14.5

Propylene 42.5 Isobutane 12.9 n-Butane 3.3

Butenes 22.1

Pentanes 0.7

The zeolite used in the process of the invention, MCM-22, is described in International Patent

Publication No WO 90/06283 and exhibits in its calcined form an x-ray diffraction pattern including the lines listed in Table I below:

More specifically, MCM-22 has an X-ray diffraction pattern in its calcined form including the lines listed in Table II below:

Alternatively, the calcined form of MCM-22 may have an X-ray diffraction pattern including the lines listed in Table III below:

Most specifically, MCM-22 has in its calcined form by an X-ray diffraction pattern including the lines listed in Table IV below:

These values were determined by standard techniques. The radiation was the K-alpha doublet of copper and a diffractometer equipped with a scintillation counter and an associated computer was used. The peak heights, I, and the positions as a function of 2 theta, where theta is the Bragg angle, were determined using algorithms on the computer associated with the diffractometer. From these, the relative intensites, 100 I/Io. , where Io is the intensity of the strongest line or peak, and d (obs.) the interplanar spacing in Angstrom Units (A) , corresponding to the recorded lines, were determined. In Tables A-D, the relative intensities are given in terms of the symbols W = weak, M = medium, S = strong, VS = very strong. In terms of intensities, these may be generally designated as follows: W = 0-20 M = 20-40 S 40-60

VS = 60-100 Zeolite MCM-22 has a composition involving the molar relationship:

X₂0₃:(n)Y0₂, wherein X is a trivalent element, such as aluminum, boron, iron and/or gallium, preferably aluminum, -Y is a tetravalent element such as silicon and/or germanium, preferably silicon, and n is at least 10, usually from 10 to 150, more usually from 10 to 60, and even more usually from 20 to 40. In the as-synthesized form, zeolite MCM-22 has a formula, on an anhydrous basis and in terms of moles of oxides per n moles of Y0-_>., as follows:

(0.005-0.l)Na₂0: (l-4)R:X₂0.-:nY0₂; wherein R is an organic directing agent, usually hexamethylene imine. The Na and R components are associated with the zeolite as a result of their presence during crystallization, and are easily removed by post-crystallization methods hereinafter more particularly described.

Zeolite MCM-22 is thermally stable and exhibits

2 high surface area greater than 400 m /gm as measured by the BET (Bruenauer, Emmet and Teller) test. As is evident from the above formula, MCM-22 is synthesized nearly free of Na cations. It can, therefore, be used as an olefin conversion catalyst with acid activity without an exchange step. To the extent desired, however, the original sodium cations of the as-synthesized material can be replaced in accordance with techniques well known in the art, at least in part, by ion exchange with other cations. Preferred replacing cations include metal ions, hydrogen ions, hydrogen precursor, e.g., ammonium, ions and mixtures thereof. Particularly preferred cations are those which tailor the activity of the catalyst for olefin interconversion. These include hydrogen, rare earth metals and metals of Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB and VIII of the Periodic Table of the Elements.

The zeolite MCM-22 olefin conversion catalyst herein can also be used in intimate combination with a hydrogenating component such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or a noble metal such as platinum or palladium where a hydrogenation-dehydrogenation function is to be performed. Such component can be introduced in the catalyst composition by way of cocrystallization, exchanged into the composition to the extent a Group IIIA element, e.g., aluminum, is in the structure, impregnated therein or intimately physically admixed therewith. Such component can be impregnated in, or on, the zeolite such as, for example, by, in the case of platinum, treating the zeolite with a solution containing a platinum metal-containing ion. Thus, suitable platinum compounds for this purpose include chloroplatinic acid, platinous chloride and various compounds containing the platinum amine complex.

Zeolite MCM-22 can be prepared from a reaction mixture containing sources of alkali or alkaline earth metal (M) , e.g., sodium or potassium, cation, an oxide of trivalent element X, e.g, aluminum, an oxide of tetravalent element Y, e.g. , silicon, an organic (R) directing agent, preferably hexamethylene i ine, and water, said reaction mixture having a composition, in terms of mole ratios of oxides, within the following ranges:

In a preferred method of synthesizing zeolite MCM-22, the YO- reactant contains a substantial amount of solid Y0₂, e.g., at least about 30 wt.% solid YO.. Where Y0₂ is silica, the use of a silica source containing at least about 30 wt.% solid silica, e.g., Ultrasil (a precipitated, spray dried silica containing about 90 wt.% silica) or HiSil (a precipitated hydrated SiO_ containing about 87 wt.% silica, about 6 wt.% free H-0 and about 4.5 wt.% bound H O of hydration and having a particle size of about 0.02 micron) favors crystal formation from the above mixture. If another source of oxide of silicon, e.g., Q-Brand (a sodium silicate comprised of about 28.8 wt.% of Si0₂, 8.9 wt.% ^Na ₂° ^{and 62}*³ wt.% H₂0) is used, crystallization may yield impurity phases of other crystal structures, e.g., ZSM-12. Preferably, therefore, the Y0₂, e.g., silica, source contains at least about 30 wt.% solid Y0_, e.g., silica, and more preferably at least about 40 wt.% solid YO,, e.g., silica.

Crystallization of the MCM-22 crystalline material can be carried out at either static or stirred conditions in a suitable reactor vessel such as, e.g., polypropylene jars or teflon-lined or stainless steel autoclaves. Crystallization is preferably effected at a temperature of 80^βC to 225^βC for a time of 25 hours to 60 days. Thereafter, the crystals are separated from the liquid and recovered.

Synthesis of the MCM-22 crystals is facilitated by the presence of at least about 0.01 percent, preferably about 0.10 percent and still more preferably about 1 percent, seed crystals (based on total weight) of the crystalline product.

It may be desirable to incorporate the MCM-22 crystalline material with another material which is resistant to the temperatures and other conditions employed in the olefin conversion process of this invention. Such materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and/or metal oxides such as alumina. The latter may be either naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. Use of a material in conjunction with zeolite MCM-22, i.e., combined therewith or present during its synthesis, which itself is catalytically active may change the conversion and/or selectivity of the catalyst. Inactive materials suitably serve as diluents to control the amount of conversion so that the higher value olefin products can be obtained economically without employing other means for controlling the rate of reaction. These materials may be incorporated into naturally occurring clays, e.g., bentonite and kaolin, to improve the crush strength of the catalyst. Said materials, i.e., clays, oxides, etc. , function as binders for the catalyst. It is desirable to provide a catalyst having good crush strength because in commercial use, it is desirable to prevent the catalyst from breaking down into powder-like materials. These clay binders have been employed normally only for the purpose of improving the crush strength of the catalyst.

Naturally occurring clays which can be composited with MCM-22 crystals include the montmorillonite and kaolin family, which families include the subbentonites, and the kaolins commonly known as Dixie, McNamee, Georgia and Florida clays or others in which the main mineral constituent is halloysite, kaolinite. dickite, nacrite, or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification. Binders useful for compositing with zeolite MCM-22 also include inorganic oxides, notably alumina.

In addition to the foregoing materials, the MCM-22 crystals can be composited with a porous matrix material such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania as well as ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia silica-alumina-magnesia and silica-magnesia-zirconia.

It may also be advantageous to provide at least a part of the foregoing matrix materials in colloidal form so as to facilitate extrusion of the bound catalyst component(s) .

The relative proportions of finely divided crystalline material and inorganic oxide matrix vary widely, with the crystal content ranging from 1 to 90 percent by weight and more usually, particularly when the composite is prepared in the form of beads, in the range 2 to 80 weight percent of the composite.

The stability of the catalyst of this invention may be increased by steaming. U.S. Patent Nos.

4,663,492; 4,594,146; 4,522,929; and 4,429,176 describe conditions for the steam stabilization of zeolite catalysts which can be utilized to steam-stabilize the catalyst for use herein. The steam stabilization conditions include contacting the catalyst with, e.g.,

5-100% steam at a temperature of at least about 300°C

(e.g., 300-650°C) for at least one hour (e.g., 1-200 hours) at a pressure of 101-2,500 kPa. In a more particular embodiment, the catalyst can be made to undergo steaming with 75-100% steam at 315°-500°C and atmospheric pressure for 2-25 hours. The invention will now be more particularly described with reference to the following examples and the accompanying drawings, in which:

Figures 1 and 2 are graphs comparing the butene-2 yield and C_g+ yield respectively for MCM-22 and a conventional silica-alumina catalyst in the isomerization of butene-1; and

Figures 3 to 6 are graphs comparing the properties of MCM-22 and [B]MCM-22 in the interconversion of propylene.

In examples illustrative of the synthesis of zeolite MCM-22, whenever sorption data are set forth for comparison of sorptive capacities for water, cyclohexane and/or n-hexane, they were Equilibrium Adsorption values determined as follows:

A weighed sample of the calcined absorbent was contacted with the desired pure absorbate vapor in an adsorption chamber, evacuated to less than 1 mm Hg and contacted with 12 Torr of water vapor or 40 Torr of n-hexane or 40 Torr of cyclohexane vapor, pressures less than the vapor-liquid equilibrium pressure of the respective adsorbate at 90°C. The pressure was kept constant (within about ± 0.5 mm Hg) by addition of adsorbate vapor controlled by a manostat during the adsorption period, which did not exceed about 8 hours. As adsorbate was adsorbed by the MCM-22 crystalline material, the decrease in pressure caused the manostat to open a valve which admitted more adsorbate vapor to the chamber to restore the above control pressures. Sorption was complete when the pressure change was not sufficient to activate the manostat. The increase in weight was calculated as the adsorption capacity of the sample in g/100 g of calcined adsorbant.

When Alpha Value is examined, it is noted that the Alpha Value is an approximate indication of the catalytic cracking activity of the catalyst compared to a standard catalyst and it gives the relative rate constant (rate of normal hexane conversion per volume of catalyst per unit time) . It is based on the activity of the highly active silica-alumina cracking catalyst taken as an Alpha of 1 (Rate Constant = 0.016 sec -1) . The Alpha Test is described in U.S. Patent

3,354,078, in the Journal of Catalysis. Vol. 4, p. 527 (1965); Vol. 6, p. 278 (1966); and Vol. 61, p. 395 (1980) . The experimental conditions of the test used herein include a constant temperature of 538°C and a variable flow rate as described in detail in the

Journal of Catalysis. Vol. 61, p. 395.

EXAMPLE 1

One part of sodium aluminate (43.5% A1₂0_, 32.2% Na₂0, 25.6% H₂0) was dissolved in a solution containing 1 part of 50% NaOH solution and 103.13 parts H₂0. To this was added 4.50 parts hexamethyleneimine. The resulting solution was added to 8.55 parts of Ultrasil, a precipitated, spray-dried silica (about 90% Sio ) . The reaction mixture had the following composition, in mole ratios:

where R is hexamethyleneimine. The mixture was crystallized in a stainless steel reactor, with stirring, at 150"C for 7 days. The crystalline product was filtered, washed with water and dried at 120°C. After a 20 hour calcination at 538°C, the X-ray diffraction pattern contained the major lines listed in Table V. The sorption capacities of the calcined material were measured to be:

The surface area of the calcined crystalline material

2 was measured to be 494 m /g.

The chemical composition of the uncalcined material was determined to be as follows: Component wt.%

Si0₂ 66.9

A1₂0₃ 5.40

Na 0.03

N 2.27 Ash 76.3

Si0₂/Al₂0_, mole ratio = 21.1

Degrees 2-Theta

2.0 4.02 7.10 7.95 10.00 12.90 14.34 14.72 15.90 17.81 20.20 20.91 21.59 21.92 22.67 23.70 24.97 25.01 26.00 26.69 27.75 28.52 29.01 29.71 31.61 32.21 33.35 34.61

EXAMPLE 2

A sample of H-MCM-22 prepared according to the method outlined in Example 1 was compared with a commercial silica-alumina catalyst, Sorbead W (Kali-Chemie) , for olefin isomerization. The properties of Sorbead W are listed below in Table VI.

TABLE VI PHYSICAL PROPERTIES OF SORBEAD W

Alumina Content 10 wt% Pore Volume 0.50 cc/g

Pore Diameter 30 A

2 Surface Area 750 m /g

In a typical experiment, the catalyst was sized to 14/24 mesh and 10 cc were loaded into a 1/2" stainless steel fixed bed micro-unit. The catalyst bed was heated to 430^βC (800°F) with 100 cc/min of dry nitrogen flowing through the unit. The catalyst bed was held at 430°C (800°F) for one hour before cooling to 320°C (600°F). The unit was pressurized to 450 kPa (50 psig) , and a pure 1-butene feed (Matheson) was admitted at 1 gram/gram catalyst/hr. The nitrogen flow was adjusted to give l/l mol/mol N-/HC. The temperature of the reactor was lowered from 320°C (600°F), initially, to a final temperature of 150°C (300°F) in 55°C (100°F) increments. The total effluent from the reactor at each temperature was anlyzed with an on-line gas chromatograph equipped with a 30 meter megabore DB-1 column.

The yields of 2-butene from H-MCM-22 and Sorbead W catalysts are plotted as a function of temperature in Figure 1. Both catalysts produced near equilibrium amounts of 2-butene at about 400°F. However, Sorbead W yielded at best about 80 wt% 2-butenes while H-MCM-22 gave roughly 85 wt% 2-butenes from the 1-butene feed. H-MCM-22 was also found to be more selective at near-equilibrium 2-butene yields. Figure 2 shows the yield of C_g+ product for both catalysts as a function of temperature. H-MCM-22 produced significantly less heavy products (<5 wt%) from the 1-butene feed at temperatures below 230°C (450°F). The reactivity data show that H-MCM-22 can give near-equilibrium amounts of isomerized product from olefinic feeds, and can be more selective than a commercial silica-alumina catalyst, Sorbead W, for olefin isomerization (less C-.+ product) .

EXAMPLE 3

Another zeolite MCM-22 sample was prepared by adding 4.49 parts quantity of hexamethyleneimine to a mixture containing 1.00 part sodium aluminate, 1.00 part 50% NaOH, 8.54 parts Ultrasil VN3 and 44.19 parts deionized H-,0. The reaction mixture was heated to 143°C (290°F) and stirred in an autoclave at that temperature for crystallization. After full crystallinity was achieved, the majority of the hexamethyleneimine was removed from the autoclave by controlled distillation and the zeolite crystals separated from the remaining liquid by filtration, washed with deionized H.,0 and dried. The zeolite was then calcined in nitrogen at 540°C, exchanged with an aqueous solution of ammonium nitrate and calcined in air at 540°C. The zeolite was tabletted, crushed and sized to 30/40 mesh.

The MCM-22 catalyst had the following properties: Surface Area (BET) , m²/g 503 Si0₂/ l₂0₃ (molar) Na, ppm Alpha

Sorption Properties, wt.%

H₂0 cyc₆ ^n"C6 Ash at 1000°C, wt.%

EXAMPLE 4 This example illustrates the conversion of propylene to an isoalkene-rich product containing isobutene, isoamylenes, and C6+ gasoline employing zeolite MCM-22 prepared in Example 3 as catalyst, and compared with prior art amorphous silica alumina and ZSM-5 catalysts. The conditions of the MCM-22 conversion reaction were 400-410°C, 210 kPa and an WHSV of 10 hr^" ( based on active catalyst solids) . The experiments were carried out in small tubular fixed bed reactor using chemically pure propene (propylene, C ^~) feed. In the standard procedure, the catalyst was charged to the reactor and the reactor heated to 230°c (450^βF) in a nitrogen stream. Nitrogen was slowly replaced by propylene at 10 WHSV and 210 kPa.

Temperature exotherm was adjusted to 400°C. At the desired reaction temperture, the liquid product and off-gases were collected and analyzed by gas chromatography using a fused silica capillary column. The results are set forth in Table VII as follows: Catalyst Used

Feed

Average Reactor Temp., "C. HSV (hr ) Pressure (kpa)

Yields twt% .

3 Conv iC_; + ic-

The data contained in Table VII demonstrate that MCM-22 gives excellent propylene conversion and good selectivity to the desirable isobutylene and isoamylenes. In Table VII the performance of MCM-22 is compared with ZSM-5 and alumina-bound amorphous silica/alumina catalyst. Clearly, MCM-22 is far superior to the amorphous catalyst, both in terms of activity and isobutylene and isoamylene yields. Its performance is comparable with that of ZSM-5, though it ages more rapidly than the latter. However, the effects of catalyst aging may be minimized if the process is run in a fluidized bed mode with continuous regeneration.

With MCM-22, the side reactions involving hydrogen transfer and leading to saturates, mainly isoparaffins, decrease with time on-stream. The C-+ fraction is rich in linear and branched mono-olefins, and can be recycled for further conversion to isobutylene and isoamylenes. EXAMPLE 5 In a further preparation of the present zeolite, 4.49 parts of hexamethyleneimine was added to a solution containing 1 part of sodium aluminate, 1 part of 50% NaOH solution and 44.19 parts of H₂0. To the combined solution were added 8.54 parts of Ultrasil silica. The mixture was crystallized with agitation at 145°C for 59 hours and the resultant product was water washed and dried at 120°C. Product chemical composition, surface area and adsorption analyses results were as set forth in Table VIII:

1000g of uncalcined MCM-22 was exchanged with IN NH.NO., for one hour at room temperature. The zeolite was filtered, washed, and the exchange procedure was repeated. The ammonium exchanged MCM-22 was washed, dried, and calcined for three hours in N₂ at 480^βC (900^βF) and for nine hours at 540°C (1000°F) in air.

The final material had an alpha value of 310, a surface area of 470 m 2/g and contained 135 ppm Na. EXAMPLE 6 Preparation of [B]MCM-22 Borosilicate Catalyst

This example illustrates preparation of the zeolite MCM-22 in which X of the general formula, supra. is boron. Boric acid, 2.2 parts, was added to a solution of 1 part of 50% NaOH solution and 73.9 parts H₂0. To this solution was added 15.3 parts of HiSil silica followed by 6.7 parts of hexamethyleneimine. The reaction mixture was crystallized in a stainless steel reactor, with agitation, at 150°C (300°F) for 72 hours. The crystalline product was filtered, washed with water and dried at 120°C.

The chemical composition of the calcined material was determined to be as follows: Component Wt.%

N 1.23

Na 0.16

Boron 0.66

^Al2°3 °"²⁵ Si0₂ 59.6

Ash 61.3

The as-synthesized material had a Si0₂/Al₂0 ratio of 400 and a Si0₂/B₂0₃ ratio of 32.4. In preparing the catalyst for evaluation, the as-synthesized material was precalcined for six hours in N₂ at 480°C (900°F) .

The [B]MCM-22 catalyst was prepared by exchanging the precalcined material with IN NH₄N0₃ buffered to pH=8 with NH.OH, for one hour at room temperature. The catalyst was filtered, washed, and the exchange procedure was repeated three times for a total of four exchanges. The ammonium exchanged [B]MCM-22 was washed, dried, and calcined for one hour in N₂ at 480°C

(900°F) and for six hours in air at 540°C (1000°F) .

The final material had an alpha value acid activity of 2, a surface area of 370 m 2/g, and contained 220 ppm

Na. EXAMPLE 7 The catalysts of Examples 5 an 6 were evaluated in a reactor unit as described in Example 4 and compared with the amorphous silica-alumina. The results clearly show the advantage of the low acidity [B]MCM-22. The [B]MCM-22 catalyst depicted in Figures 3-6 was significantly more stable as shown in the attached figure. Also, at high propylene conversion (>70 wt%) , the [B]MCM-22 catalyst gave a higher yield of the desired tertiary C. and C.. olefins.

Claims

CLAIMS :

1. A process for converting a lower olefin feedstock to an iso-alkene rich product by contacting the feedstock with a catalyst comprising a synthetic porous crystalline zeolite which, in its calcined form, has an x-ray diffraction pattern including the values listed in Table I of the specification.

2. The process of Claim 1 wherein the synthetic porous crystalline zeolite has an X-ray diffraction pattern including values listed in

Table II of the specification.

3. The process of Claim 1 wherein the synthetic porous crystalline zeolite has an X-ray diffraction pattern including values listed in Table III of the specification.

4. The process of Claim 1 wherein the synthetic porous crystalline zeolite has an X-ray diffraction pattern including values listed in Table IV of the specification.

5. The process of Claim 1 wherein the synthetic porous crystalline zeolite has a composition comprising the molar relationship

X₂0₃:(n)Y0₂, wherein n is at least 10, X is a trivalent element and Y is a tetravalent element.

6. The process of Claim 1 wherein the conversion is olefin isomerization and is effected at a temperature of 0 to 650°C, a pressure of 100 to 14000 kPa (1 to 2000 psia) and a weight hourly space velocity of 0.1 to 500.

7. The process of Claim 6 wherein the conversion is effected at a temperature of 150 to 250°C.

8. The process of Claim 6 wherein the feedstock includes n-butene.

9. The process of Claim 1 wherein the conversion is olefin interconversion of a C, 3-C1,6_ olefin feed to a product rich in tertiary C. and C_ olefins and is effected at a temperature of 250 to 700°C, a pressure of 100 to 1500 kpa, and an LHSV of 0.1 to 100.

10. The process of Claim 9 wherein the olefin interconversion is effected at a temperature of 300 to 450°C, a pressure of 150 to 500 kpa and an LHSV Of 0.2 to 20.