OLIGOMERIZATION PROCESSES

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Serial No. 61/380,606, filed September 7, 2010, and EP Application No. 10188409.6, filed October 21, 2010, the disclosures of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

[0002] The invention relates to particles comprising zeolite catalysts and their use in oligomerization processes. In particular, particles (for example, lobed particles such as extrudates) are made from compositions comprising the product of at least one zeolite catalyst and at least one binder.

BACKGROUND OF THE INVENTION

[0003] The condensation reaction of an olefin or a mixture of olefins over an acid catalyst to form higher molecular weight products is a widely used commercial process. This type of condensation reaction may be referred to as an oligomerization reaction, and the products are generally low molecular weight oligomers that are formed by the condensation of up to 12, typically 2, 3, or 4, but up to 5, 6, 7, or even 8 olefin molecules with each other. For example, low molecular weight olefins (such as, for example, propene, 2-methylpropene, 1- butene, 2-butenes, pentenes, and hexenes) may be converted by oligomerization processes using zeolite catalysts to produce oligomers. Exemplary uses of such oligomers include high- octane gasoline blending stocks, starting material for the production of chemical intermediates, and other end-products. Such chemical intermediates and end-products include alcohols, acids, detergents, and esters such as plasticizer esters and esters for synthetic lubricants.

[0004] Industrial oligomerization processes employing zeolite catalysts typically run for several weeks before a catalyst change is required or a decommissioning of the reactor is needed. In industrial processes, zeolite catalysts are generally delivered as particles, for example, spheres, cylinders, tablets, and extrudates of a composition of the catalysts and at least one binder. See, for example, U.S. Patent Application Publication Nos.: 2006/0199987; 2009/0216056; and WO 2007/006398. Extrudates may have many shapes and may be distinguished by their shape or number of lobes of each extrudate, for example, cylindrical (solid or hollow), trilobe, quadrulobe, (or simply multilobe). [0005] The feedstocks for the reactions are generally obtained from refining activities such as a stream derived from catalytic or steam cracking that may have been subjected to fractionation. The nature of such refining activities is such that there will be variations in the constituents of the feedstocks. In addition, it may be desirable to change the nature of the feed during a reactor run. Thus, the catalyst activity and the reaction conditions vary according to the composition of the feedstock. As a result, the ideal catalyst provides not only the ability to run a long time as referred to in terms of catalyst life, catalyst activity, or catalyst stability but is also able to oligomerize selectively to produce desired end products using a variety of heterogeneous feedstocks that may contain isomers, poisons, and saturated and unsaturated molecules. Furthermore, the reactions are exothermic and the size of the exotherm also depends upon the nature and amount of the constituents of the feedstock. For example, if isobutylene and propylene are present, they are particularly reactive generating a large amount of heat of reaction.

[0006] The high temperatures generated may lead to carbonaceous deposits on the catalyst caused by a build up of condensed, heavy hydrocarbons similar to asphalt. Such deposits are commonly termed "coke" and lead to deactivation of the zeolite catalyst. In general, the higher the concentration of olefin in the feed, the higher will be the rate of heat release from the catalyzed reaction, and thus, the higher the temperatures reached. Consequently, there will be a higher rate of coke formation and deposition of coke on the catalyst particle. As a result, this has placed a limit on the maximum concentration of olefin that can be tolerated in the feed.

[0007] Useful feed streams containing olefins such as C3 and C4 olefins may be refinery streams derived from steam cracking or catalytic cracking and the composition of the stream will depend upon the raw material from which it is produced and the production technology employed. For example, propylene refinery streams may typically contain up to 75 wt% propylene with the balance being predominantly propane. Similarly butene refinery streams may typically contain up to 70 wt% butenes with the balance being predominantly butanes. Poisons, such as, for example, nitrogen containing compounds (e.g., nitriles) and sulfur containing compounds, and isomeric equivalents are also most likely present. Thus, the reactivity of the olefins in oligomerization processes with zeolite catalysts varies according to the nature of the olefin, its concentration in the feedstock, and other variable constituents.

[0008] Background references include U.S. Patent Nos.: 3,960,978; 4,016,218; 4,021 ,502; 4,381 ,255; 4,560,536; 4,919,896; 5,446,222; 5,672,800; 6,039,864; 6, 143,942; 6,517,807; 6,884,914; U.S. Patent Application Publication Nos. : 2006/0199987; 2007/015945; 2009/0216056; 2009/240008; EP 0 220 933 A; EP 746 538 A; WO 1994/12452; WO 2005/058777; WO 2005/1 18512; WO 2005/118513; WO 2006/133908; WO 2006/133967; WO 2007/006398; WO 2007/104385; WO 2008/074511; WO 2008/088452; WO 2009/153420; Interaction of Acetonitrile with Olefins and Alcohols in Zeolite H-ZSM-5: In Situ-State NMR Characterization of the Reaction Products, Alexander G. Stepanov, Mikhail V. Luzgin, Chem. Eur. J., 1997, 3, No. 1 , pp. 47-56; and Analysis of Coke Deposition Profiles in Commercial Spent Hydroproces ing Catalysts Using Raman Spectroscopy, Bas M. Vogelaar et al, Fuel 86 (2007), pp. 1 122-1 129.

[0009] Therefore, there remains a need for improvements in extrudates comprising zeolite catalysts that provide for extended production runs as measured by, for example, catalyst life, yielding desired end products as measured by, for example, olefin selectivity. Additionally, there remains a need for the particles to be able to oligomerize olefins in presence of higher concentrations of catalyst poisons and yet yield higher concentrations of the desired end product. It will be appreciated that in large scale industrial processes, small increases in production (such as >1%) have highly significant value.

SUMMARY OF THE INVENTION

[0010] In a class of embodiments, the invention provides for particles, for example, extrudates, comprising zeolite catalysts and their use in oligomerization processes. In particular embodiments, extrudates are made from compositions comprising the product of at least one zeolite catalyst and at least one binder; wherein the extrudates have an average particle size of from 1.6 mm (about 1/16 ^th inch) or less or, alternatively, from 1.3 mm (about 1720 ^th inch) or less. The extrudates may be shaped particles, for example, lobed particles comprising two or more lobes.

[0011] In several of these embodiments, the extrudates demonstrate improvements in or related to catalyst life and/or olefin selectivity for olefin oligomerization.

[0012] In some embodiments, at least one C ₄ or greater alkane may be present during oligomerization to improve reactor continuity and/or mitigate the presence of poisons on the catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a bar chart showing the catalyst life as a function of extrudate size at a reactor temperature of 310°C of the Examples 1 and 2. [0014] Figure 2 is a plot of olefin conversion as a function of catalyst life of the Examples 3 and 4.

[0015] Figure 3 is a plot of olefin selectivity as a function of olefin conversion of the Examples 3 and 4.

DETAILED DESCRIPTION

[0016] Before the present compounds, components, compositions, and/or methods are disclosed and described, it is to be understood that unless otherwise indicated this invention is not limited to specific compounds, components, compositions, reactants, reaction conditions, structures, or the like, as such may vary, unless otherwise specified. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0017] It must also be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless otherwise specified.

[0018] Oligomerization processes described herein employ extrudates made from compositions comprising the product of at least one zeolite catalyst and at least one binder; wherein the extrudates have an average particle size of from 1.6 mm (about 1/16 ^th inch) or less or, alternatively, from 1.3 mm (about l/20 ^th inch) or less.

[0019] The composition may include or be made with optional processing aids or other optional components.

[0020] Embodiments of inventive processes may exhibit improvements in or related to catalyst life and olefin selectivity for olefin oligomerization.

[0021] In some embodiments, at least one C ₄ or greater alkane may be present during oligomerization to improve reactor continuity and/or mitigate the presence of poisons on the extrudate.

ZEOLITE CATALYSTS

[0022] The catalysts utilized in the oligomerization processes of embodiments of the invention, i.e., at least one zeolite catalyst, may be any suitable zeolite catalyst(s) capable of oligomerizing olefins. Zeolites are the alumino silicate members of the family of microporous solids known as "molecular sieves." The term molecular sieve refers to a particular property of these materials, i.e., the ability to selectively sort molecules based primarily on a size exclusion process. This is due to a very regular pore structure of molecular dimensions. The maximum size of the molecular or ionic species that can enter the pores of a zeolite is controlled by the dimensions of the channels. These are conventionally defined by the ring size of the aperture, where, for example, the term "8-ring" refers to a closed loop that is built from 8 tetrahedrally coordinated silicon or aluminum atoms and 8 oxygen atoms. These rings are not always perfectly symmetrical due to a variety of effects, including strain induced by the bonding between units that are needed to produce the overall structure, or coordination of some of the oxygen atoms of the rings to cations within the structure. Therefore, the pores in many zeolites may not be cylindrical.

[0023] In an embodiment, the at least one zeolite catalyst may include a medium pore size molecular sieve having a Constraint Index of about 1 to about 12. Constraint Index and a method of its determination are described in, for example, U.S. Patent No. 4,016,218.

[0024] Examples of the at least one zeolite catalyst include those of the TON structure type (for example, ZSM-22, ISI-1, Theta-1 , Nu-10, and KZ-2), those of the MTT structure type (for example, ZSM-23 and KZ-1), those of the MFI structure type (for example, ZSM- 5), those of the MFS structure type (for example, ZSM-57), those of the MEL-structure type (for example, ZSM-11), those of the MTW structure type (for example, ZSM-12), those of the EUO structure type (for example, EU-1), those of the AEL structure type (for example, SAPO-1 1), members of the ferrierite family (for example, ZSM-35) and members of the ZSM-48 family of molecular sieves (for example, ZSM-48). Other examples include MWW (e.g., MCM-22, MCM-48), MOR, or beta type catalysts. As used herein, the term "structure type" is used as described in the Structure Type Atlas, Zeolites 17, 1996.

[0025] In an embodiment, the at least one zeolite catalyst is selected from at least one of ZSM-5, ZSM-11, ZSM-12, ZSM-18, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM- 50, ZSM-57, and mixtures thereof.

[0026] In a class of embodiments, the at least one zeolite catalyst comprises molecular sieves having pores formed by 10-membered rings of tetrahedrally coordinated atoms, such as molecular sieves having the TON or MFS structure type.

[0027] Mixtures of two or more of catalysts may be used in the processes. For example, the mixture may include ZSM-22 and ZSM-57 or ZSM-22 and ZSM-5 or ZSM-57 and ZSM- 5. The at least one zeolite catalyst may also be combined with other catalysts such as a solid phosphoric acid (sPa) catalyst.

[0028] In a class of embodiments, the at least one zeolite catalyst is used in its H- or acid form.

[0029] The at least one zeolite catalyst may have an average crystallite size of up to 15 μηι, such as within the range of from 0.01 to 6 urn, alternatively, from 0.05 to 5 μιη, and alternatively, from 0.1 to 3 μηι. As used herein, "average crystallite size" refers to the arithmetic average of the diameter distribution of the crystals on a volume basis.

[0030] In several embodiments, an as-synthesized molecular sieve is advantageously converted to its acid form, for example, by acid treatment, e.g., by HC1, acetic acid, etc. or by ion exchange, for example, ammonium ion exchange. Subsequently, it may undergo calcination before use. The calcined materials may be post-treated, such as by steaming.

[0031] For example, the at least one zeolite catalyst may be produced by any suitable method. One technique includes heating a reaction mixture containing a source of silicon oxide, a source of aluminum oxide and, if appropriate, an organic promoter, for example, a nitrogen or phosphorus-containing organic base, together optionally, with an alkali metal base, and separating the porous aluminosilicate crystals (zeolite precursor crystals) formed. The precursor crystals are then calcined in air or oxygen at a temperature exceeding or about 500°C, for example, at a temperature of 550°C for about 10 to about 20 hours. As recognized in the art, calcination temperatures and durations may vary depending on the type of zeolite catalyst or combination of zeolite catalysts selected. In one embodiment, the calcined material is exchanged with ammonium ions (NH ₄ +) and subjected to conditions under which the ammonium ions decompose, with the formation of ammonia and a proton, thus, producing an acidic form of the at least one zeolite catalyst. Alternatively, the acidic form of the catalyst may be obtained by acid exchange with hydrochloric acid, acetic acid, etc. If desired, however, the calcined material may be used as a catalyst without first being exchanged with ammonium ions, since the material already possesses acidic sites.

[0032] Ammonium exchanged and calcined monodimensional 10-rings zeolites (e.g., ZSM-22 and ZSM-23) may be treated to selectivate their surface, thereby, forming a selectivated catalyst. This selectivation may be achieved in numerous ways. In an embodiment, the at least one zeolite catalyst may be titrated with an organic nitrogen base, such as collidine. See, for example, U.S. Patent No. 5,026,933. Another example is by depositing a crystalline Si:Al layer on a core of zeolite where this layer has a higher Si:Al ratio than the untreated zeolite. See, for example, U.S. Patent No. 6,013,851.

[0033] Although much of the discussion above is directed to aluminosilicate zeolites, it is possible to use material in which silicon and aluminum have been replaced in whole or in part by other elements, for example, any one or more of a Group 2 to Group 15 atom. For example, silicon may be replaced by or contacted with germanium and aluminum or may be replaced with boron, gallium, chromium, and iron. As used herein, these materials containing such replacement lattice elements may also be termed zeolites.

[0034] Exemplary catalyst materials and processes for making and using may also be found in U.S. Patent Nos.: 3,960,978; 4,016,218; 4,021,502; 4,381 ,255; 4,560,536; 4,919,896; 5,446,222; 5,672,800; 6,143,942; 6,517,807; 6,884,914; U.S. Patent Application Publication No. 2006/0199987; EP 746 538 A; WO 1994/12452; WO 2005/118512; WO 2005/118513; WO 2007/006398; and WO 2008/088452. See also "Atlas of Zeolite Structure Types," Eds. W.H. Meier, D.H. Olson and Ch. Baerlocher, Elsevier, Fourth Edition, 1996. BINDERS

[0035] The at least one zeolite catalyst may be contacted with at least one binder to form a composition that may be extruded into an extrudate as discussed in more detail below. The at least one binder may be a metal oxide and/or a clay. Suitable exemplary binder materials include at least one of alumina, silica, an aluminosilicate, clay, and mixtures thereof. In an embodiment, the binder is aluminum oxide (AI ₂ O ₃ ) or commonly referred to as alumina.

[0036] For example, in an embodiment, the composition to be extruded into an extrudate may comprise alumina and ZSM-22 or the composition may comprise alumina and ZSM-57.

[0037] In a class of embodiments, the composition to be extruded into an extrudate may comprise from 10:90 to 90:10, alternatively, from 20:80 to 80:20, of the at least one zeolite catalyst to the at least one binder by weight.

[0038] In an alternative class of embodiments, the composition may comprise from 1 to 99 wt% of the at least one zeolite catalyst based upon the total weight of the composition, alternatively, from 20 to 80 wt% of the at least one zeolite catalyst based upon the total weight of the composition, alternatively, from 25 to 75 wt% of the at least one zeolite catalyst based upon the total weight of the composition, alternatively, from 30 to 75 wt% of the at least one zeolite catalyst based upon the total weight of the composition, and alternatively, from 40 to 75 wt% of the at least one zeolite catalyst based upon the total weight of the composition. The remainder of the composition may be or comprise of one or more binders and/or one or more other additives or processing aids.

EXTRUSION PROCESSING AND EXTRUDATES

[0039] The composition comprising the product of the at least one zeolite catalyst and the at least one binder may extruded by any process that is capable of producing an extrudate. As used herein, an "extrudate" is the resulting particle of a material that has been extruded through a die. As used herein, a "particle" refers to a discrete unit of material structure as discussed in Hawley's Condensed Chemical Dictionary, Richard J. Lewis Sr., 13 ^th ed., 1997, John Wiley & Sons, Inc., page 840. As used herein, "extrusion" is the process of directing, generally, using some type of mechanical force, a material through a die, for example, a metal die, typically, followed by cutting, cooling, and/or chemical hardening. Extrudates may have many shapes and may be distinguished by their shape. Examples of extrudates include but are not limited to pellets, cylindrical (solid or hollow) extrudates, trilobe extrudates, quadrulobe extrudates, etc. In several classes of embodiments, the extrudates are lobed particles comprising two or more lobes, alternatively, three, four, or more lobes. As used herein, "lobe" refers to any projecting part, for example, at least one rounded projecting part.

[0040] A typical, exemplary process for making extrudates proceeds as follows. At least one catalyst and at least one binder are mixed using any suitable method, such as mulling or kneading. The mixing is generally carried out at a temperature in the range of from 1 to 200°C but generally at ambient temperature. The mulling or kneading may be performed under any pressure, such as 0.1-10 atmospheric pressure. Typically, the process lasts from 1 min to 10 h.

[0041] The composition is usually made into stiff dough for extrusion. If necessary, a solvent may be added to the composition. Suitable solvents include water, alcohols, ethers, esters, amides, aromatic solvents, halogenated solvents, and the like, and mixtures thereof. Typical solvents include water and alcohols. Water is the most common.

[0042] The composition is then directed to an extruder usually with a force applied, for example, a mechanical force provided by a screw. The material is then pushed through a die or an orifice to create elongated objects of a fixed cross-section. The shape of the extrudate is dependent on the opening of the cross-section. Any conventional extruder may be used.

[0043] The composition to be extruded may also include one or more extrusion aids. An extrusion aid helps the mixing, mulling, and extruding operation, and may improve the mechanical and/or physical properties of the extrudate such as crush strength, surface area, pore size, or pore volume. For example, an extrusion aid may promote bridging of inorganic particles during the kneading, molding, drying, and calcination, and/or ensure the mechanical stability of the extrudate during extrusion and calcination. Extrusion aids may also help disperse solvent more homogeneously throughout the composition. Extrusion aids are well known and a listing of some extrusion aids including additional information may be found in, for example, WO 2008/088452. [0044] The extrudate may be dried. The drying process removes at least a portion or all of solvents (e.g., water, alcohols, etc.) from the extrudate. The drying may be performed at atmospheric pressure or under vacuum. The drying may occur in air or an inert atmosphere. The amount of water present in the air may be controlled and/or regulated by the use of air driers (and/or desiccants) and by the use of air moisture measurement.

[0045] The extrudate may also be calcined. Typically, calcination is carried out in an oxygen-containing atmosphere to burn off the organic materials (e.g., residual solvent, extrusion aids, templating agents, etc.) used in the manufacturing process. The calcination temperature may be carried out from 200 to 1400°C, more preferably from 450 to 1000°C. In certain embodiments, initially the extrudate is calcined in an inert atmosphere (e.g., nitrogen, helium, etc.) to thermally decompose the organic compounds contained in the extrudate, and then organic materials are burned-off in an oxygen-containing atmosphere.

[0046] Generally, for oligomerization processes, properties such as high mechanical strength, low pressure drop, and high surface area are important properties for extrudates given the demands of commercial process conditions and the desire to maximize the yield of the targeted product.

[0047] The extrudates generally have an average particle size of from 1.5875 mm (1/16 ^th inch) or less or, alternatively, from 1.2700 mm (1720 ^th inch) or less. In another embodiment, the extrudates generally have an average particle size of from 1.6 mm (about 1/16 ^th inch) or less or, alternatively, from 1.3 mm (about 1720 ^th inch) or less. As used herein, "average particle size" with reference to the extrudate refers to the arithmetic average of the diameter distribution of the extrudate, for example, weight based particle size. In other embodiments, the extrudate may have an average particle size of at least about or from .1 mm, .2 mm, .3 mm, .4 mm, or .5 mm up to and including about 1.3 mm, 1.5 mm, 1.6 mm, 2.0 mm, or 2.5 mm, including any range or combination of lower/upper ends disclosed therein.

[0048] Methods of measuring the extrudates are known and any suitable method may be used. Sieving, microscopy (e.g., electron microscopy), laser techniques have all been proposed and are useful.

[0049] A preferred example includes sieving using a mesh size in accordance with ASTM 16 and proceeding with the method of measurement provided in British Standard (BS) 1796- 1 : 1989 cross-referenced as ISO 2591-1 : 1988. This procedure is applied and used in the claims unless otherwise stated given its ease and convenience on a commercial scale to quickly isolate a large volume of particles having particular average particle size(s). [0050] For more background information, see Table 2.1 of Powder Sample and Particle Size Determination by Terence Allen, 2003, Elsevier Science and Technology Books, ISBN 9780444515643.

[0051] In a class of embodiments, hexane uptake may be used to measure the available micro-pore volume of the inventive extrudates. For example, the inventive extrudates may exhibit a hexane uptake of 40 mg hexane/gram catalyst or more, alternatively, a hexane uptake of 45 mg hexane/gram catalyst or more, alternatively, a hexane uptake of 50 mg hexane/gram catalyst or more, and alternatively, a hexane uptake of 55 mg hexane/gram catalyst or more.

[0052] In another class of embodiments, the bulk crush strength may be used to measure the resistance to fracturing of the inventive extrudates. For example, the inventive extrudates may have a bulk crush strength according to ASTM D7048 of 15 psig or more, alternatively, 20 psig or more, alternatively, 25 psig or more, and alternatively, 30 psig or more. These are important characteristics when loading and unloading catalyst particles into and out of a reactor.

[0053] In a class of embodiments, for a given population of extrudates, not all members need to be uniform and the given population may comprise non-uniform members taking into account irregularities and/or differences that may result in the manufacturing process, handling/transport, defects that develop during use or regeneration, contaminants, use of one more different types of extrudates (for example, using extrudates having different lobe numbers (including but not limited to cylinder, trilobe, quadrulobe, etc.) or using extrudates having different particle sizes, post-manufacture crushing, etc. As used herein, "uniform" refers to having the same form and size. In general classes of embodiments, a given class of extrudates comprises 30% or more uniform members, alternatively, 40% or more uniform members, alternatively, 50% or more uniform members, alternatively, 60% or more uniform members, alternatively, 70% or more uniform members alternatively, 80% or more uniform members, and, alternatively, 90% or more uniform members, based upon the total given population.

[0054] For more information regarding the extrusion process and extrudates and their use, see WO 2007/006398; WO 2008/088452; U.S. Patent Application Publication Nos. 2006/0199987; 2009/0216056; and EP 0 220 933 A. FEEDSTOCKS AND OLIGOMERIZATION PROCESSES

[0055] The feedstock typically comprises olefins having from about 2 to about 15 carbon atoms, such as, for example, from about 2 to about 6 carbon atoms. Additionally, in several embodiments, the feedstock may comprise an oligomer, such as, for example, a dimer, especially one provided by recycling a part of a product stream.

[0056] In a class of embodiments, the feedstock comprises one or more of propene, butenes, pentenes, hexenes, their isomers, and mixtures thereof. The process is especially useful for the oligomerization of feedstocks comprising propene, butenes, other components, and mixtures thereof.

[0057] As used herein, "oligomer(s)" or "oligomer product" refers to a polymer molecule (or a mixture of polymer molecules) made from a few monomer units such as, for example, a dimer, a trimer, a tetramer, a mixture thereof, etc. In a class of embodiments, "oligomer(s)" refers to a polymer molecule (or a mixture of polymer molecules) having 20 carbon atoms or less, alternatively, 15 carbon atoms or less, alternatively, 10 carbon atoms or less, alternatively, 9 carbon atoms or less, and alternatively, 8 carbon atoms or less. As used herein, "oligomerization process" refers to any process of catalytically joining monomer units to form the oligomer(s) as defined above. In a class of embodiments, oligomerization process is used synonymously with "polymerization process." As used herein, the term "oligomerization conditions" refers to any and all those variations of equipment, conditions (e.g., temperatures, pressures, etc.), materials, and reactor schemes that are suitable to conduct the oligomerization process to produce the oligomer(s) as known and applied in the art and discussed more below.

[0058] In a class of embodiments, the feedstock may contain 30 wt% or more olefins, alternatively, 40 wt% or more olefins, alternatively, 50 wt% or more olefins, alternatively, 60 wt% or more olefins, alternatively, 70 wt% or more olefins, and alternatively, 80 wt% or more olefins, based upon the total weight of the feed. The olefins to be oligomerized may be one or more of C ₃ -C15 olefins or mixtures thereof, alternatively, C ₃ -C6 olefins or mixtures thereof, and alternatively, C ₃ -C5 olefins or mixtures thereof.

[0059] The feedstock may also comprise other hydrocarbons such as, for example, at least one saturated hydrocarbon (e.g., at least one alkane) having the same or different number of carbon atoms as the olefm(s) in the feedstock.

[0060] Additionally, the feedstock may comprise isomers of any of the constituents found therein. As used herein, "isomer" refers to compounds having the same molecular formula but different structural formula. Examples may be structural isomers, stereoisomers, enantiomers, geometrical isomers, etc. Typically, the feedstock may comprise at least one isomer of the olefin(s) in the feedstock.

[0061] In a class of embodiments, the feedstock may also comprise contaminants or compound(s) that may hinder catalyst life or productivity. These may include nitrogen, sulfur, chlorine, or compounds incorporating the aforementioned elements, and mixtures thereof.

[0062] Additionally, oxygenates including ethers such as di-isopropylether (DIPE) or di- methylether (DME) may also hinder catalyst life. In some embodiments, DIPE and/or DME is removed or reduced as a pre-treatment to the feedstream. In other embodiments, DIPE and/or DME may be tolerated in the feedstream and no pre-treatment is conducted. In a class of embodiments, the oxygenate content in the feedstock may be 5000 wppm or less, alternatively, 2500 wppm or less, alternatively, 1000 wppm or less, alternatively, 500 wppm or less, and alternatively, 100 wppm or less and alternatively, 10 wppm or less.

[0063] Examples of nitrogen containing compound(s) include acetonitrile, propionitrile, ammonia, amines, and mixtures thereof. In a class of embodiments, the nitrogen content in the feedstock may be about 1.50 ppm or less, alternatively, 1.00 ppm or less, alternatively, .75 ppm or less, alternatively, .60 ppm or less, alternatively, .50 ppm or less, alternatively, .30 ppm or less, and alternatively, .25 ppm or less, by weight, calculated on an atomic basis. In other embodiments, the nitrogen content in the feedstock may be at least 1.50 ppm, alternatively, at least 1.00 ppm, alternatively, at least .75 ppm, alternatively, at least .60 ppm, alternatively, .50 ppm, and alternatively, at least .25 ppm, by weight, calculated on an atomic basis.

[0064] Examples of sulfur containing compound(s) include mercaptans such as, for example: methyl mercaptan; ethyl mercaptan; propyl mercaptan; dimethyl sulfide; diethyl sulfide; ethyl methyl sulfide; n-propyl sulfide; 1 -propane thiol; 2-propane thiol; 1 -butane thiol; 1 , 1 -methylethyl thiol; ethylmethyl disulfide; dimethyl disulfide; tetrahydrothiopene; and mixtures thereof. In a class of embodiments, the sulfur content in the feedstock may be about 3.00 ppm or less, alternatively, 2.50 ppm or less, alternatively, 2.00 ppm or less, alternatively, 1.50 ppm or less, and alternatively, 1.00 ppm or less, by weight, calculated on an atomic basis. In other embodiments, the sulfur content in the feedstock may be at least 3.00 ppm, alternatively, at least 2.50 ppm, alternatively, at least 2.00 ppm, alternatively, at least 1.50 ppm, and alternatively, at least 1.00 ppm, by weight, calculated on an atomic basis. [0065] Examples of suitable feedstocks include untreated refinery streams such as Fluidized Catalytic Cracking (FCC), coker, and pygas streams as well as aromatics- containing streams, such as, for example, reformates.

[0066] Other examples include Raffinate- 1 (RAF-1) and/or Raffinate-2 (RAF-2). Typically, Raffinate- 1 and Raffinate-2 may be regarded as stages in the processing of crude, generally, C4 streams. These streams are usually from olefin steam crackers but may also come from refinery cat-crackers in which case they generally contain the same components but in different proportions. The first stage of the process is to remove, by generally solvent extraction or hydrogenation, the butadiene which may be 40-45% of the stream. The remaining product is Raffinate- 1. It generally consists of isobutylene, the two normal isomers, butene-1 and butene-2, and smaller quantities of butanes and other compounds. Removal of the isobutylene, usually by reaction with methanol to produce MTBE, leaves Raffinate-2. Raffinate 3 (RAF-3) is less common but may also be used. Raffinate 3 may be obtained after separation of 1-butene from Raffinate 2 with a residual 1-butene content of about 1%.

[0067] In other embodiment, processes of the invention may tolerate the presence or elevated presence of dienes as opposed to solid phosphoric acid (sPa) catalysts. Zeolite catalysts are more robust catalysts as compared to sPa catalysts in, for example, propylene oligomerization where feed streams contain the presence of dienes. This is surprising because sPa catalysts have more acid sites than zeolite catalysts. This provides for the flexibility to operate with feedstreams having a higher diene content and oligomerization operation becomes less sensitive to feed irregularities or "upsets".

[0068] In another embodiment, the feedstock comprises an FCC light olefin stream that typically comprises ethane, ethylene, propane, propylene, isobutane, n-butane, butenes, pentanes, and other optional components. A specific example of such a feedstock may comprise the following:

Wt% Mol%

Ethane 3.3 5.1

Ethylene 0.7 1.2

Propane 4.5 15.3

Propylene 42.5 46.8

Isobutane 12.9 10.3

n-Butane 3.3 2.6 Butenes 22.1 18.32

Pentanes 0.7 0.4

[0069] In several classes of embodiments the feedstock may comprise a diluent. The diluent may comprise any suitable hydrocarbon such as alkanes or a mixture comprising at least one alkane. The alkanes may be represented the general formula: C _n H2 _n +2, wherein n is a number from 1 to 20, alternatively, from 1 to 10, alternatively, from 1 to 5, and alternatively, from 3 to 4. Examples may include methane, ethane, propane, butane, pentane, and mixtures thereof. The at least one alkane may be linear, branched, cyclic, or be a mixture thereof. In a class of embodiments and when the diluent is present, the feedstock may comprise at least 10%, at least 25%, at least 30%, at least 35%, or at least 40% of the diluent, for example, the alkane such as propane and/or butane, based upon the total volume of the feedstock. Alternatively stated, the diluent or at least one alkane may be present in the feedstock in the range of from 10% to 60%, alternatively, 10% to 40%, alternatively, from 10% to 35%, and alternatively, from 20% to 35%, based upon the total volume of the feedstock. The diluent may also be delivered to the reactor(s) through separate feedstreams. When fed separately, the diluent may be fed in amounts to be equivalent to the embodiments wherein the diluent is co-fed with the feedstock. These amounts may not necessarily be the same as the ranges stated above given that more or less of the diluent may be necessary when fed separately to provide an equivalent. In some embodiments, the diluent, when present, may improve reactor continuity and/or mitigate the presence of poisons on the catalyst.

[0070] Additionally, the feedstock may undergo further processing and purification steps prior to being introduced in the oligomerization reactor(s).

[0071] In several classes of embodiments and prior to oligomerization, the feedstock may be hydrated (i.e., contacted with water) and in an embodiment sufficient water may be added to saturate the feedstock. In particular, the feedstock may comprise from about 0.01 to about 0.25, alternatively, from about 0.02 to about 0.20, and alternatively, from about 0.03 to about 0.10, mol% water based on the total hydrocarbon content of the feedstock. If desired and by way of example, the water content of the feedstock may be increased by passage through a thermostatted water saturator.

[0072] The reaction system may include one or more of a fixed bed reactor, a packed bed reactor, a tubular reactor, a fluidized bed reactor, a slurry reactor, and/or a continuous catalyst regeneration reactor. They may be operated in any combination such as, for example, in series and/or parallel sequence. In several embodiments, they may be operated in continuous or batch mode.

[0073] The oligomerization conditions may include operating temperatures from about 80°C to about 350°C. Close to and above the upper end of the range, deoligomerization rates increase and may predominate over the oligomerization reaction providing an upper limit to practical operation. More typically, the reaction temperature is from about 130°C to about 320°C, alternatively, from about 135°C to about 310°C, and alternatively, from about 160°C to about 270°C.

[0074] The pressure may be in the range of from about 400 psig to about 4000 psig (2860 to 27680 kPa), and alternatively, from about 500 psig to about 1500 psig (3550 to 10440 kPa).

[0075] The olefin weight hourly space velocity may be in the range of from about 0.1 hr ^"1 to about 20 hr ^"1 or from about 0.5 hr ^"1 to about 5 hr ^"1 .

[0076] In one embodiment, process is conducted at a temperature of 80-350°C; an olefin weight hourly space velocity of 0.1-20 hr ^"1 ; and a pressure of 2860-27680 kPa.

[0077] In another embodiment, the process is conducted at a temperature of 130-320°C; an olefin weight hourly space velocity of 0.5-5 hr ^"1 ; and a pressure of 3550-10440 kPa.

[0078] In a class of embodiments, the oligomer product may include a hydrocarbon composition comprising at least 80 wt%, alternatively, at least 90 wt% based upon the total weight of the reactor effluent (the final reactor effluent if one or more reactors are utilized) of a Cs to C ₂ o olefin or a mixture thereof.

[0079] In a class of embodiments, the catalyst may undergo a pre-treatment step in order to address or mitigate the effects of exotherms. For example, the zeolite catalyst may be pre- treated to temporarily reduce the catalyst activity during the initial phase of the reaction, commonly referred to as "start-up." After such time, the catalyst reactivates enabling a smooth operation and without compromising catalyst length.

[0080] In particular and in an embodiment, a zeolite catalyst, preferably dry, is contacted with a light olefin and/or heavier molecular weight paraffin, at temperatures, for example, from ambient temperature to 100°C. This pre-treated catalyst is then fed into the reactive zone of the reactor. Without being bound to theory, it is believed that waxy molecules fill the micropores of the catalyst, inhibiting catalyst activity during start-up. After start-up, the catalyst is able to eliminate the waxy molecules that were inhibiting activity or regenerate itself and the catalyst continues to stable operation. [0081] This pre-treatment method is especially useful when starting and shutting down reactors in between routine maintenance or when switching between catalyst types. For example, standard tubular units may control several tubular reactors, such as from three to five, at a single temperature with a single steam drum. When these reactors are brought into operation, it is not possible to temporarily tailor the temperature of each reactor to manage the exotherms associated with zeolite catalysts. In contrast, solid phosphoric acid catalyst (sPa) are generally not prone to large exotherms during start-up. Thus, the pre-treatment step is useful to manage exotherms of zeolite catalyst during start-up. This flexibility allows for a zeolite catalyst to be substituted in a reactor system that previously utilized sPa catalysts with from little to no equipment modification or addition.

[0082] In a more specific embodiment, ZSM-22 may be treated with a heavy hydrocarbon in a fashion that only temporarily fills at least some of the catalyst's micropores that ultimately blocks the active sites of those pores, leading to temporarily inhibition and a reduction of exotherms. Under oligomerization conditions, without being bound to theory, the heavy hydrocarbons slowly crack/desorb thereby fully restoring the catalyst activity to support stable operation.

[0083] Additionally, this pre-treatment technique may use blends or mixtures of treated and un-treated catalyst to achieve optimal, tailored operating conditions.

[0084] The oligomer product is useful in many applications and is the starting material for further processes. For example, the oligomer product may be polymerized to produce polyolefms that have application in the plastic industry and synthetic basestocks for lubricants. The oligomer product may undergo hydroformylation and subsequently hydrogenation to produce alcohols. The alcohols may be used in industry such as, for example, solvents, or serve as building blocks for surfactants. The alcohols may further be used in many other areas of industry such as, for example, undergoing esterification to produce esters that have application as plasticizers.

CATALYST LIFE

[0085] As used herein, "catalyst life" (Tpdt/Tcat) describes the number of tons of product produced per ton of formulated catalyst. It may be plotted against a setpoint temperature at a given space velocity and at a given olefin conversion rate. For example, a plot may provide a comparison between oligomerization processes using inventive extrudates (for example, 1716 ^th inch (1.5875 mm) and 1720 ^th inch (1.2700 mm) extrudates) and conventional extrudates or those extrudates having a larger average particle size (for example, l/8 ^th inch (3.175 mm) or 1/10 ^th inch (2.54 mm) extrudates).

[0086] In a class of embodiments, inventive extrudates may provide for a comparable or longer catalyst life (as represented by Tpdt/Tcat) at a desirable conversion. For example, these embodiments may enjoy a comparable or an increase in catalyst life as compared to conventional extrudates i.e., of the same chemical composition but having a larger average particle size (for example, 1/8 ^Λ inch (3.175 mm) or 1/10 ^th inch (2.54 mm) extrudates), of .5% or greater, alternatively, of 1% or greater, alternatively, of 3% or greater, alternatively, of 5% or greater, alternatively, of 10% or greater, alternatively, of 15% or greater, alternatively, of 20% or greater, alternatively, of 30% or greater, alternatively, of 40% or greater, and alternatively, of 50% or greater, at oligomerization temperatures of from 180°C to 320°C, alternatively, 210°C to 300°C, alternatively, 210°C to 250°C, and alternatively, 210°C to 240°C, at an olefin constant conversion rate of from 60 to 99 wt% based upon the total weight of olefins, alternatively, from 70 to 95 wt%, alternatively, from 75 to 99 wt%, alternatively, from 75 to 95 wt%, and alternatively, at about 75 wt%. The space velocity for the aforementioned embodiments may be in the range of 1 to 20 h ^"1 . In an embodiment, the space velocity is 12 h ^"1 .

[0087] In another class of embodiments, inventive extrudates provide for a longer catalyst life and at desirable olefin conversion rates as compared to conventional extrudates i.e., of the same chemical composition but having a larger average particle size (for example, 1/8 ^ώ inch (3.175 mm) or 1/10 ^th inch (2.54 mm) extrudates). For example, these embodiments may enjoy an increase in catalyst life of from 2750 Tpdt/Tcat or greater, alternatively, 3000 Tpdt/Tcat or greater, alternatively, 3100 Tpdt/Tcat or greater, alternatively, 3500 Tpdt Tcat or greater, alternatively, 4000 Tpdt/Tcat or greater, alternatively, 5000 Tpdt/Tcat or greater, (alternatively stated, from any one of the aforementioned numerical values to 10,000 Tpdt/Tcat to provide a closed numerical range) at oligomerization temperatures from 180°C to 320°C, alternatively, 210°C to 300°C, alternatively, 210°C to 250°C, and alternatively, 210°C to 240°C, at an olefin constant conversion rate of from 60 to 99 wt% based upon the total weight of olefins, alternatively, from 70 to 95 wt%, alternatively, from 75 to 99 wt%, alternatively, from 75 to 95 wt%, and alternatively, at about 75 wt%. The space velocity for the aforementioned embodiments may be any one of 1 , 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 h ^"1 . In an embodiment, the space velocity is 12 h ¹ . OLEFIN SELECTIVITY

[0088] Embodiments described herein may exhibit improvements in olefin selectivity at given conversion rates that result in higher oligomer yield. Olefin selectivity may be defined as the weight of olefins having a given carbon number divided by the total weight of the product. For example, olefin selectivities may increase, as compared to conventional extrudates (for example, 1/8 ¹¹¹ inch (3.175 mm) or 1710 ^th inch (2.54 mm) extrudates), by 1 wt% or greater, alternatively, 2 wt% or greater, 3 wt% or greater, alternatively, 4 wt% or greater, alternatively, 5 wt% or greater, alternatively, 6 wt% or greater, alternatively, 7 wt% or greater, alternatively, 8 wt% or greater, alternatively, 9 wt% or greater, and alternatively, 10 wt% or greater, based upon the total weight of the product at an olefin constant conversion rate of from 50 to 99 wt% based upon the total weight of olefins in feed, alternatively, from 70 to 95 wt%, alternatively, from 75 to 99 wt%, alternatively, from 75 to 95 wt%, and alternatively, at about 75 wt%, and at oligomerization temperatures from 180°C to 320°C, alternatively, 210°C to 300°C, alternatively, 210°C to 250°C, and alternatively, 210°C to 240°C. The space velocity for the aforementioned embodiments may be any one of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 h ¹ . In an embodiment, the space velocity is 12 h ^"1 .

[0089] In several classes of embodiments, olefin selectivity may be directed to the production of C6-C i6 oligomers or mixtures thereof from C ₃ -C6 feedstocks or mixtures thereof, alternatively, C7-C8-C9 oligomers or mixtures thereof from C ₃ -C4 feedstocks or mixtures thereof.

EXAMPLES

[0090] It is to be understood that while the invention has been described in conjunction with the specific embodiments thereof, the foregoing description is intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications will be apparent to those skilled in the art to which the invention pertains.

[0091] Therefore, the following examples are put forth so as to provide those skilled in the art with a complete disclosure and description and are not intended to limit the scope of that which the inventors regard as their invention.

Example 1

[0092] ZSM57/alumina extrudates (1/10 ^th inch quadrulobes) were used to process a 45 wt% n-butenes / 55 wt% butanes feedstock. Reaction conditions were 8000 kPa (80 bar), WHSV between 8 and 12 hr ^"1 , and a 170 to 310°C feedstock inlet temperature. Olefin conversion was maintained at 75% conversion. A catalyst life of 1 900 T product /T catalyst (Tpdt/Tcat) (as defined above) was achieved at a reactor temperature of 310°C as is shown in Figure 1.

Example 2

[0093] ZSM57/alumina extrudates (1/16 ^th inch quadrulobes) were used to process a 45 wt% n-butenes / 55 wt% butanes feedstock. Reaction conditions were 8000 kPa (80 bar), WHSV between 8 and 12 hr ¹ , and a 170 to 310°C feedstock inlet temperature. Olefin conversion was maintained at 75% conversion. A catalyst life of 18360 T product /T catalyst (Tpdt/Tcat) (as defined above) was achieved at a reactor temperature of 310°C as is shown in Figure 1.

Example 3

[0094] ZSM57/alumina extrudates (1/16 ^th inch quadrulobes) were used to process 65 wt% n-butenes / 25 wt% n-butane / 10 wt% isobutane feedstock. Reaction conditions were 7000 kPa (70 bar), WHSV between 6 and 18 hr ^"1 , and at 170 to 240°C feedstock inlet temperature. The temperature required to maintain 75% of olefin conversion is shown in Figure 2 (triangles) as a function of catalyst life (weight product/weight catalyst). A catalyst life of 3000 T product / T catalyst (Tpdt/Tcat) (as defined above) was reached at ~240°C. Cg selectivity data at 12 WHSV are plotted (triangles) in Figure 3. At 74% conversion the C ₈ selectivity is ~ 79 wt%.

Example 4

[0095] ZSM57/alumina extrudates (1/20 ^Λ inch quadrulobes) were used to process 65 wt% n-butenes / 25 wt% n-butane / 10 wt% isobutane feedstock. Reaction conditions were 7000 kPa (70 bar), WHSV between 6 and 18 hr 1, and at 170 to 220°C feedstock inlet temperature. The temperature required to maintain 75% of olefin conversion is shown in Figure 2 (solid spheres) as a function of catalyst life (weight product/weight catalyst). A catalyst life of 3000 T product / T catalyst (Tpdt/Tcat) (as defined above) was reached at ~220°C. C ₈ selectivity data at 12 WHSV are plotted (solid spheres) in Figure 3. At 74% conversion, the Cs selectivity is ~ 86 wt%.

[0096] The phrases, unless otherwise specified, "consists essentially of and "consisting essentially of do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the invention, additionally, they do not exclude impurities and variances normally associated with the elements and materials used. [0097] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0098] All priority documents are herein fully incorporated by reference for all jurisdictions in which such incorporation is permitted and to the extent such disclosure is consistent with the description of the present invention. Further, all documents and references cited herein, including testing procedures, publications, patents, journal articles, etc. are herein fully incorporated by reference for all jurisdictions in which such incorporation is permitted and to the extent such disclosure is consistent with the description of the present invention.