CHLORIDES TO OLEFINS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U. S. Provisional Patent Application No. 62/240,735, filed October 13, 2015, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

A. Field of the Invention

[0002] The invention generally concerns the use of mixed-templated silicoaluminophosphate (SAPO) molecular sieve catalysts to catalyze the reaction of alkyl halides to light olefins. In particular, a SAPO-34 catalyst prepared using mixed structure- directing agents including tetraethylammonium hydroxide (TEAOH) and one or more of morpholine, diethylamine (DEA), and triethylamine (TEA) provides a more efficiently produced catalyst when compared with typical SAPO-34 catalysts. Further, the mixed- templated catalysts of the present invention provide good conversion of alkyl halides and selectivity for C2-C4 olefins.

B. Description of Related Art

[0003] Light olefins such as ethylene and propylene are used by the petrochemical industry to produce a variety of key chemicals that are then used to make numerous downstream products. By way of example, both of these olefins are used to make a multitude of plastic products that are incorporated into many articles of manufacture. FIGS. 1 A and IB provide examples of products generated from ethylene (FIG. 1 A) and propylene (FIG. IB).

[0004] Methane activation to higher hydrocarbons, especially to light olefins, has been the subject of great interest over many decades. Recently, the conversion of methane to light olefins via a two-step process that includes conversion of methane to methyl halide, particularly to methyl mono-halide, for example, to methyl chloride followed by conversion of the halide to light olefins has attracted great attention. Micro pore zeolite (e.g., ZSM-5) or zeolite type catalysts (e.g., SAPO-34) have been commonly employed for methyl chloride (or other methyl halide) conversion reactions. However, the selectivity to a desired olefin (e.g., propylene), rapid catalyst deactivation due to carbon deposition (coking), and the synthesis cost of the catalyst remain the major challenges for scale-up and commercial success of the reaction.

[0005] The synthesis of SAPO-34 catalysts can involve multiple protocols and subtle changes in the preparative details can result in dramatic alteration in the properties of the final catalysts. For instance, the silicon source, structuring directing agents, crystallization conditions, and material composition in initial gel formation, can influence the average crystal size of the catalyst {See, for example, Razavian et al. in "Recent Advances in Silicoaluminophosphate Nanocatalysts Synthesis Techniques and Their Effects on Particle Size Distribution, Reviews on Advancement of Material Science, 2011, Vol. 29, pp. 83-99). Template synthesis techniques have been employed to prepare SAPO-34. The use of tetraethylammonium hydroxide (TEAOH), although relatively expensive, has become a popular choice to provide catalysts with preferred crystal morphology (size, shape, dispersion, surface area, distribution) and surface Bransted acidity. By way of example, Chinese Patent No. 101525141 to Chengdu Huien Fine Chem Co.; Ltd. describes a method for preparing a SAPO-34 molecular sieve templated from TEAOH for catalytically converting methyl chloride into C2-C3 olefins.

[0006] Other references including Masoumi et al. in Applied Catalysis A (2015), 493, pp. 103-111; Lee et al. in Applied Catalysis A (2007), 329, pp. 130-136; Wang et al. in Microporous and Mesoporous Materials (2012), 152, pp. 178-184; and Sedighi et al. in RSC Adv. (2014), 4, pp. 49762-49769 all concern the methanol to olefin (MTO) reaction and the design of SAPO-34 catalysts specific to this reaction. The MTO reaction process requires the presence of an alcohol {e.g., methanol) in the feed stream and involves a cascade of reactions performed under acidic conditions. Catalyst choice, topology and acidity, as well as specific process conditions determine the overall MTO activity and selectivity. MTO reactions are comparable to alkyl halide to olefin {e.g., chloromethane to olefin CTO) reactions in that they both catalyse the formation of olefins from activated methane. However, the overall reaction mechanisms of these reactions in the presence of SAPO-34 catalysts are not fully understood, and different products, activities, and selectivities can be realized from the different starting materials using the same catalyst. For example, in addition to olefins, CTO reactions can produce aromatic compounds and hydrogen chloride, while MTO reactions can produce ethers {e.g., dimethyl ether). {See, for example, Wei et al, Chinese Journal of Catalysis, 2012, 33 : 1 1-21). Without wishing to be bound by theory, it is believe that the difference in the two reactions is due to the difference in electron affinity between methanol and chloromethane and the catalyst surface. Thus, when MTO catalysts are used in CTO reactions, lower activity is generally realized. SUMMARY OF THE INVENTION

[0007] A discovery has been made that addresses the problems associated with using SAPO-34 catalysts in alkyl halide to olefin reactions (e.g., low activity). The discovery also provides a solution to the high costs associated with the synthesis of silicoaluminophosphate (SAPO) molecular sieve catalysts used in the alkyl halide to light olefin (e.g., C ₂ -C4 olefins) reaction process. The discovery is premised on a SAPO-34 catalyst prepared using a mixed template including tetraethylammonium hydroxide (TEAOH) and one or more of morpholine, diethylamine (DEA), and triethylamine (TEA). Without wishing to be bound by theory, it is believed that the amount of TEAOH that is typically used to prepare SAPO-34 catalysts can be reduced via the presence of morpholine, diethylamine (DEA), or triethylamine (TEA), thereby lowering the overall preparation costs of the catalyst. Surprisingly, the reduction in TEAOH does not negatively affect the resulting catalyst performance, as the mixed-templated catalysts of the present invention have comparatively good conversion and selectivity properties in the alkyl halide to light olefin reaction process.

[0008] In one aspect of the present invention, there is disclosed a method for converting an alkyl halide to an olefin, the method includes contacting a mixed-templated SAPO-34 catalyst with a feed including an alkyl halide under reaction conditions sufficient to produce an olefin hydrocarbon product comprising C ₂ -C4 olefins where the mixed-templated SAPO- 34 catalyst has been templated from a mixture including TEAOH and at least one of morpholine, DEA, or TEA. In one aspect, the mixed-templated SAPO-34 catalyst used in the method has been templated from a mixture including TEAOH and morpholine. Using the above mentioned catalyst, the maximum combined selectivity of ethylene and propylene is at least 70%, preferably at least 80%>, more preferably at least 90%, or most preferably 90% to 98%), the maximum combined space time yield (STY) of ethylene and propylene is at least 1/hr or 1/hr to 3/hr, the maximum conversion of alkyl halide is at least 65% or 70% to 80%, and/or the maximum selectivity of ethylene is 50% to 60%> and the maximum selectivity of propylene is 35% to 45%. In another aspect, the mixed-templated SAPO-34 catalyst used in the method has been templated from a mixture including TEAOH and DEA, or from a mixture including TEAOH and TEA, or from a mixture including TEAOH and at least two of or all three of morpholine, DEA, and TEA. In some aspects of the method, the reaction conditions for converting an alkyl halide to an olefin include a temperature from 300 °C to 500 °C, a pressure of 0.5 MPa or less, and a weighted hourly space velocity (WHSV) of 0.5 to 10 h ^"1 . The alkyl halide used in the method can be a methyl halide and the feed can include about 10 mole % or more of a methyl halide. The methyl halide can be methyl chloride, methyl bromide, methyl fluoride, or methyl iodide, or any combination thereof. In other aspects the feed stream of the method includes less than 5 wt.% alcohol, preferably less than 1 wt. % alcohol, or preferably is alcohol free, and in a particular aspect the alcohol is methanol.

[0009] In certain aspects of the method, the reaction for converting an alkyl halide to an olefin occurs in a fluid catalytic cracking (FCC) process or reactor or fluidized circulating bed process or reactor. The method can further include collecting or storing the produced olefin hydrocarbon product and using the produced olefin hydrocarbon product to produce a petrochemical or a polymer. The method can also include regenerating the used/deactivated catalyst in a continuous process such as a FCC-type process or reactor or a circulating catalyst bed process or reactor.

[0010] In some aspects of the method, the mixed-templated SAPO-34 catalyst is the reaction product of heat treatment of a synthesis mixture having a molar composition of: aSi:bAl:cP:dTEAOH:eTEA:fmorpholine:gDEA:hH ₂ 0, where a is 0 to 1 ; b is 0 to 1 ; c is 0 to 1 ; d is 0.1 to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, where at least one of e, f, or g is greater than zero, and the heat treatment includes (a) heating the synthesis mixture to obtain a crystalline material and (b) calcining the crystalline material.

[0011] In another embodiment of the present invention there is disclosed a system for producing olefins. The system can include an inlet for a feed including the alkyl halide discussed above and throughout this specification, a reaction zone that is configured to be in fluid communication with the inlet. The reaction zone can includes the feed and a mixed- templated SAPO-34 catalyst that has been templated from a mixture including TEAOH and at least one of morpholine, DEA, or TEA. The system can include an outlet configured to be in fluid communication with the reaction zone to remove an olefin hydrocarbon product from the reaction zone. During use, the reaction zone can further include a FCC-type reactor or a circulating catalyst bed reactor, and a collection device that is capable of collecting the olefin hydrocarbon product. In some aspects, the system includes a mixed-templated SAPO-34 catalyst that has been templated from a mixture including TEAOH and morpholine, from a mixture including TEAOH and DEA, from a mixture including TEAOH and TEA, or from a mixture including TEAOH and at least two of or all three of morpholine, DEA, and TEA. In one aspect of the system, the mixed-templated SAPO-34 catalyst is the reaction product of heat treatment of a synthesis mixture having a molar composition of: aSi:bAl:cP:dTEAOH:eTEA:fmorpholine:g:DEA:hH ₂ 0, where a is 0 to 1 ; b is 0 to 1 ; c is 0 to 1 ; d is 0.1 to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, where at least one of e, f, or g is greater than zero, and the heat treatment includes (a) heating the synthesis mixture to obtain a crystalline material and (b) calcining the crystalline material. The alkyl halide used in the system can be a methyl halide and the feed can include about 10 mole % or more of a methyl halide. The methyl halide can be methyl chloride, methyl bromide, methyl fluoride, or methyl iodide, or any combination thereof. In other aspects the feed stream of the system includes less than 5 wt.% alcohol, preferably less than 1 wt. % alcohol, or preferably is alcohol free, and in a particular aspect the alcohol is methanol. [0012] In still another embodiment, there is disclosed a method for preparing a silicoaluminophosphate (SAPO)-34 catalyst for use in an alkyl halide to olefin reaction. The method can include: (a) obtaining a synthesis mixture comprising water, an aluminum source, a phosphorous source, a silicon source, a first templating agent that includes tetraethyl ammonium hydroxide (TEAOH), and at least a second templating agent that includes morpholine, diethylamine (DEA), or triethylamine (TEA), or any combination of the second templating agent or all of the second templating agents; (b) treating the synthesis mixture with heat to obtain a crystalline material; and (c) calcining the crystalline material to obtain the SAPO-34 catalyst. The step (a) synthesis mixture can include: aSi:bAl:cP:dTEAOH:eTEA:fmorphaline:gDEA:hH ₂ 0, where a is 0 to 1 ; b is 0 to 1; c is 0 to 1; d is 0.1 to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, and where at least one of e, f, or g is greater than zero. The heating step (b) and calcining step (c) can be performed to remove the templating agent. The heating step (b) can be performed at 150 °C to 250 °C, preferably 175 °C to 225 °C, or more preferably at 200 °C to 215 °C for a desired amount of time in an autoclave with or without agitation. After heating, the crystalline material can be separated and washed with water, and then dried at about 90 °C. The calcining step (c) can be performed in air at 400 °C to 700 °C, preferably 450 °C to 650 °C, or more preferably from 500 °C to 600 °C, for a sufficient period of time (e.g., 3 to 10 hours) to remove any remaining templating agents.

[0013] Also disclosed in the context of the present invention are embodiments 1-33. Embodiment 1 is a method for converting an alkyl halide to an olefin, the method comprising contacting a mixed-templated SAPO-34 catalyst with a feed comprising an alkyl halide under reaction conditions sufficient to produce an olefin hydrocarbon product comprising C2-C4 olefins, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethyl ammonium hydroxide (TEAOH) and at least one of morpholine, diethylamine (DEA), or triethylamine (TEA). Embodiment 2 is the method of embodiment 1, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and morpholine. Embodiment 3 is the method of embodiment 2, wherein the maximum combined selectivity of ethylene and propylene is at least 70%, preferably at least 80%, or more preferably 90% to 98%, wherein the maximum combined space time yield of ethylene and propylene is at least 1/hr or 1/hr to 3/hr, and/or wherein the maximum conversion of alkyl halide is at least 65% or 70% to 80%. Embodiment 4 is the method of embodiment 3, wherein the maximum selectivity of ethylene is 50% to 60%) and the maximum selectivity of propylene is 35% to 45%. Embodiment 5 is the method of embodiment 1, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and diethylamine (DEA). Embodiment 6 is the method of embodiment 1, wherein the mixed- templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and triethylamine (TEA). Embodiment 7 is the method of embodiment 1, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and at least two of or all three of morpholine, diethylamine (DEA), and triethylamine (TEA). Embodiment 8 is the method of any one of embodiments 1 to 7, wherein the reaction conditions include a temperature from 300 °C to 500 °C, a pressure of 0.5 MPa or less, and a weighted hourly space velocity (WHSV) of 0.5 to 10 h ^"1 . Embodiment 9 is the method of any one of embodiments 1 to 8, wherein the alkyl halide is a methyl halide. Embodiment 10 is the method of embodiment 9, wherein the feed comprises about 10 mole % or more of a methyl halide. Embodiment 11 is the method of any one of embodiments 9 to 10, wherein the methyl halide is methyl chloride, methyl bromide, methyl fluoride, or methyl iodide, or any combination thereof. Embodiment 12 is the method of any one of embodiments 1 to 11, wherein the feed stream includes less than 5 wt.% alcohol, preferably less than 1 wt. % alcohol, or preferably is alcohol free. Embodiment 13 is the method of embodiment 12, wherein the alcohol is methanol. Embodiment 14 is the method of any one of embodiments 1 to 13, wherein the reaction occurs in a fluid catalytic cracking (FCC) reactor or fluidized circulating bed reactor. Embodiment 15 is the method of any one of embodiments 1 to 14, further comprising collecting or storing the produced olefin hydrocarbon product. Embodiment 16 is the method of any one of embodiments 1 to 15, further comprising using the produced olefin hydrocarbon product to produce a petrochemical or a polymer. Embodiment 17 is the method of any one of embodiments 1 to 16, further comprising regenerating used/deactivated catalyst in a continuous process such as a fluid catalytic cracking (FCC)-type process or reactor or a circulating catalyst bed process or reactor. Embodiment 18 is the method of any one of embodiments 1 to 17, wherein the mixed- templated SAPO-34 catalyst is the reaction product of heat treatment of a synthesis mixture having a molar composition of: aSi:bAl:cP:dTEAOH:eTEA:fmoiphaline:gDEA:hH ₂ 0, where a is 0 to 1; b is 0 to 1; c is 0 to 1; d is 0.1 to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, wherein at least one of e, f, or g is greater than zero. Embodiment 19 is the method of embodiment 18, wherein the heat treatment comprises: (a) heating the synthesis mixture to obtain a crystalline material; and (b) calcining the crystalline material. [0014] Embodiment 20 is the system for producing olefins, the system comprising: an inlet for a feed comprising an alkyl halide; a reaction zone that is configured to be in fluid communication with the inlet, wherein the reaction zone comprises the feed and a mixed- templated SAPO-34 catalyst that has been templated from a mixture comprising tetraethyl ammonium hydroxide (TEAOH) and at least one of morpholine, diethylamine (DEA), or triethylamine (TEA); and an outlet configured to be in fluid communication with the reaction zone to remove an olefin hydrocarbon product from the reaction zone. Embodiment 21 is the system of embodiment 20, wherein the reaction zone includes a fluid catalytic cracking (FCC)-type reactor or a circulating catalyst bed reactor. Embodiment 22 is the system of any one of embodiments 20 to 21, further comprising a collection device that is capable of collecting the olefin hydrocarbon product. Embodiment 23 is the system of any one of embodiments 20 to 22, wherein the mixed-tempi ated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and morpholine. Embodiment 24 is the system of any one of embodiments 20 to 22, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and diethylamine (DEA). Embodiment 25 is the system of any one of embodiments 20 to 22, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and triethylamine (TEA). Embodiment 26 is the system of any one of embodiments 20 to 22, wherein the mixed-templated SAPO-34 catalyst has been templated from a mixture comprising tetraethylammonium hydroxide (TEAOH) and at least two of or all three of morpholine, diethylamine (DEA), and triethylamine (TEA). Embodiment 27 is the system of any one of embodiments 20 to 26, wherein the mixed-templated SAPO-34 catalyst is the reaction product of heat treatment of a synthesis mixture having a molar composition of: aSi:bAl:cP:dTEAOH:eTEA:fmorphaline:g:DEA:hH ₂ 0, where a is 0 to 1 ; b is 0 to 1 ; c is 0 to 1 ; d is 0.1 up to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, wherein at least one of e, f, or g is greater than zero. Embodiment 28 is the system of embodiment 27, wherein the heat treatment comprises: (a) heating the synthesis mixture to obtain a crystalline material; and (b) calcining the crystalline material. Embodiment 29 is the system of any one of embodiments 20 to 28, wherein the alkyl halide is a methyl halide. Embodiment 30 is the system of embodiment 29, wherein the feed comprises about 10 mole % or more of a methyl halide. Embodiment 31 is the system of any one of embodiments 29 to 30, wherein the methyl halide is methyl chloride, methyl bromide, methyl fluoride, or methyl iodide, or any combination thereof. Embodiment 32 is the system of any one of embodiments 20 to 31, wherein the feed stream includes less than 5 wt.% alcohol, preferably less than 1 wt. % alcohol, or preferably is alcohol free. Embodiment 33 is the system of embodiment 32, wherein the alcohol is methanol. [0015] The following includes definitions of various terms and phrases used throughout this specification. [0016] The term "catalyst" means a substance which alters the rate of a chemical reaction. "Catalytic" means having the properties of a catalyst.

[0001] The term "conversion" means the mole fraction (i.e., percent) of a reactant converted to a product or products. [0017] The term "selectivity" refers to the percent of converted reactant that went to a specified product, for example, C2-C4 olefin selectivity is the % of alkyl halide that formed C2-C4 olefins.

[0018] The term "about" or "approximately" are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the terms are defined to be within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0019] The term "substantially" and its variations are defined as being largely but not necessarily wholly what is specified as understood by one of ordinary skill in the art. In one non-limiting embodiment, substantially refers to ranges within 10%, within 5%, within 1%, or within 0.5%.

[0020] The terms "inhibiting" or "reducing" or "preventing" or "avoiding" or any variation of these terms, when used in the claims and/or the specification includes any measurable decrease or complete inhibition to achieve a desired result.

[0021] The term "effective," as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0022] The use of the words "a" or "an" when used in conjunction with any of the terms "comprising," "including," "containing," or "having," in the claims or the specification may mean "one," but it is also consistent with the meaning of "one or more," "at least one," and "one or more than one." [0023] The terms "wt.%", "vol.%", or "mol.%" refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt.% of component. [0024] The words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include") or "containing" (and any form of containing, such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0025] The catalysts of the present invention can "comprise," "consist essentially of," or "consist of particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phase "consisting essentially of," in one non- limiting aspect, a basic and novel characteristic of the catalysts of the present invention are their ability to selectivity produce light olefins, and in particular, ethylene and propylene, from alkyl halides {e.g., methyl chloride).

[0026] Other objects, features and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIGS. 1A and IB depict illustrations of various chemicals and products that can be produced from ethylene (FIG. 1 A) and propylene (FIG. IB).

[0028] FIG. 2 depicts a system for producing olefins from alkyl halides using the catalyst of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0029] The currently available SAPO catalysts, particularly SAPO-34 catalysts, show high activity for alkyl halide conversion with selectivity to light olefins {e.g., ethylene and propylene). One particular catalyst, a SAPO-34 catalyst prepared from a template reaction with tetraethyl ammonium hydroxide (TEAOH), results in a catalyst having desirable small crystal size and surface Bransted acidity. Disadvantageously, TEAOH is a fairly expensive reagent, thus limiting the use of a SAPO-34/TEAOH catalyst in scale up and commercial applications.

[0030] A discovery has been made, where methods and systems for the production of C ₂ - C ₄ olefins from alkyl halides are provided using a mixed-templated SAPO-34 catalyst. The mixed template catalyst has been templated from a mixture including tetraethylammonium hydroxide (TEAOH) and at least one of morpholine, diethylamine (DEA), or triethylamine (TEA). The preparation of the catalysts reduces the amount of TEAOH required to prepare a SAPO-34/TEAOH catalyst without sacrificing catalytic conversion or selectivity. Further, the catalysts used in the methods and systems of the current invention have been shown to have maximum combined selectivity of ethylene and propylene of at least 90% or ranging from 90% to 98%.

[0031] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Mixed-Template SAPO-34 Catalysts [0032] SAPO catalysts have an open microporous structure with regularly sized channels, pores or "cages." These materials are sometimes referred to as "molecular sieves" in that they have the ability to sort molecules or ions based primarily on the size of the molecules or ions. SAPO materials are both microporous and crystalline and have a three-dimensional crystal framework of P0 ₄ ⁺ , A10 ₄ ^~ and Si0 ₄ tetrahedra. Among developed catalysts, silicoaluminophosphate SAPO-34 molecular sieve having 8-membered ring pore sizes of 0.43-0.50 nm, relatively mild acidity, and good thermal/hydrothermal stability, is recognized as a good catalyst for methanol to olefin (MTO) reactions.

[0033] The SAPO-34 catalysts of the present invention are prepared as mixed-template SAPO-34 catalysts using structure-directing agents in a template reaction. In coordination chemistry, a template reaction is a ligand-based reaction that occurs between two or more adjacent coordination sites on a metal center. The addition of a structure-directing or template agent/ion effects the pre-organization provided by the coordination sphere and can results in significant modification of physical/chemical/electronic properties of the template complex formed. Herein in the current invention, the addition of structure-directing or template agents/ions including organic amines such as tetraethylammonium hydroxide (TEAOH), tetramethylammonium hydroxide (TMAOH), diisopropylamine (DIPA), diisopropylethylamine (DIPEA), morpholine, piperidine, pyrrolidine, diethylamine (DEA), triethylamine (TEA), or alkyl derivatives thereof can have profound effects on the resultant crystal morphology (size, shape, dispersion, surface area, distribution) and surface Bransted acidity of the mixed-template SAPO-34 catalyst formed. [0034] Non-limiting examples of making SAPO catalysts of the present invention are provided in the Examples section. Generally, SAPO catalysts are prepared using a gel containing aluminum (Al), phosphorus (P) and silicon (Si) compounds with structure- directing agents under crystallization conditions. By way of example, a method of making the SAPO catalysts can include preparing an aqueous mixture of aluminum iso-propoxide with phosphoric acid and, optionally hydrochloric acid. Colloidal silica can be added to the aluminum/phosphorous mixture with agitation followed by the addition of tetraethyl ammonium hydroxide (TEAOH) and at least one of morpholine, diethylamine (DEA), or triethylamine (TEA) to form a synthesis mixture. The synthesis mixture can have a general structure: aSi:bAl:cP:dTEAOH:eTEA:fmorphaline:gDEA:hH ₂ 0 where a is 0 to 1 ; b is 0 to 1 ; c is 0 to 1 ; d is 0.1 to 2; e is 0 to 6; f is 0 to 4; g is 0 to 4; and h is 30 to 80, and at least one of e, f, or g is greater than zero. For example, the synthesis mixture can embody a range of structure-direction agents such as 0.4Si: lAl: lP: >0.1-2TEAOH:0- 4morpholine:60H ₂ O or preferably 0.48ί: 1Α1: 1Ρ:

0.4Si: lAl: lP:>0.1-2TEAOH:0-4DEA:60H ₂ O or preferably

0.4Si: lAl: lP: lTEAOH: lDEA:60H ₂ O, 0.4Si: lAl: lP:>0.1-2TEAOH:0-4DEA:60H ₂ O, and preferably 0.4Si: 1 Al: 1P:0.2TEAOH: 1 8TEA:60H ₂ O,

0.4Si: 1A1: lP:>0.1-2TEAOH:0-4morpholine:0-4DEA:60H ₂ O or preferably

0.4Si: 1A1: lP: lTEAOH:0.5morpholine:0.5DEA:60H ₂ O,

0.4Si: 1A1: lP:>0.1-2TEAOH:0-4morpholine:0-4TEA:60H ₂ O or preferably

0.4Si: 1A1: lP: lTEAOH:0.5morpholine:0.2TEA:60H ₂ O,

0.4Si: 1A1: 1 P : >0.1 -2TEAOH: 0-4DE A: 0-4TEA: 60H ₂ O or preferably

0.4Si: 1A1: lP: 1.5TEAOH:0.2DEA:0.2TEA:60H ₂ O,

0.4Si: 1A1: 1 P : >0.1 -2TE AOH: 0-4morpholine : 0-4DE A: 0-4TE A: 60H ₂ O or preferably 0.4Si: 1A1: lP: lTEAOH:0.5morpholine:0.5DEA:0.1TEA:60H ₂ O or preferably

0.4Si: 1A1: lP: lTEAOH:0.5morpholine:0.5DEA:0.1TEA:60H ₂ O. The synthesis mixture can then be heat treated to form a crystalline material. The heat treatment can be performed at 150 °C to 250 °C, preferably 175 °C to 225 °C, or more preferably at 200 °C to 215 °C for a desired amount of time (e.g., 20 to 36 hours, or 24 hours) in an autoclave with or without agitation. After heating, the crystalline material can be separated, washed with water, dried at about 90 °C, and then calcined to remove any remaining templating agent. The calcining step can be performed in air at 400 °C to 700 °C, preferably 450 °C to 650 °C, or more preferably from 500 °C to 600 °C, for a sufficient period of time (e.g., 3 to 10 hours).

[0035] Without wishing to be bound by theory, it is believed that SAPO-34 catalysts prepared using a mixed-template of structure-directing agents provides effects on the chemical composition, morphology, and surface acidity that benefit the methods and systems for converting alkyl halides to olefins as currently disclosed.

B. Alkyl Halide Feed

[0036] The alkyl halide feed includes one or more alkyl halides. The alkyl halide feed may contain alkyl monohalides, alkyl dihalides, alkyl trihalides, preferably alkyl monohalide with less than 10% of other halides relative to the total halides. The alkyl halide feed may also contain nitrogen, helium, steam, and so on as inert compounds. The alkyl halide in the feed may have the following structure: C _n H ₍ 2 _n +2 ₎ -mXm, where n and m are integers, n ranges from 1 to 5, preferably 1 to 3, even more preferably 1, m ranges 1 to 3, preferably 1, X is Br, F, I, or CI. In particular aspects, the feed may include about 10, 15, 20, 40, 50 mole% or more of the alkyl halide. In a particular embodiment, the feed contains up to 10 mole% or more of a methyl halide. In preferred aspects, the methyl halide is methyl chloride, methyl bromide, methyl fluoride, or methyl iodide, or any combination thereof. The feed stream can also include alcohol. The feed stream can also include some alcohol. In a particular embodiment, the feed stream includes less than 5 wt.% alcohol, preferably less than 1 wt. % alcohol, or preferably is alcohol free (e.g., less 0.01 wt.%, or 0 wt.% or not detectable alcohol). In one instance, the alcohol is methanol.

[0037] The production of alkyl halide, particularly of methyl chloride (CH ₃ C1, See Equation (I) below), is commercially produced by thermal chlorination of methane at 400 °C to 450 °C and at a raised pressure. Catalytic oxychlorination of methane to methyl chloride is also known. In addition, methyl chloride is industrially made by reaction of methanol and HC1 at 180 °C to 200 °C using a catalyst. Alternatively, methyl halides are commercially available from a wide range of sources (e.g., Praxair, Danbury, CT; Sigma-Aldrich Co. LLC, St. Louis, Mo.; BOC Sciences USA, Shirley, NY). In preferred aspects, methyl chloride and methyl bromide can be used alone or in combination.

C. Olefin Production

[0038] The mixed-template SAPO-34 catalysts of the present invention (I) help to catalyze the conversion of alkyl halides to C ₂ -C4 olefins such as ethylene, propylene and butenes. The following non-limiting two-step process is an example of conversion of methane to methyl chloride and conversion of methyl chloride to ethylene, propylene and butylene. The second step (Equation III) illustrates the reactions that are believed to occur in the context of the present invention:

(I)

9CH ₃ X C ₂ H ₄ + C ₃ H ₆ + C ₄ H ₈ + 9HX (III)

Besides the C ₂ -C4 olefins the reaction may produce byproducts such as methane, C ₅ olefins, C ₂ -C5 alkanes and aromatic compounds such as benzene, toluene and xylene. [0039] Conditions sufficient for olefin production (e.g., ethylene, propylene and butylene as shown in Equation (III)) include temperature, time, alkyl halide concentration, space velocity, and pressure. The temperature range for olefin production may range from about 300 °C to 500 °C, preferably ranging 350 °C to 450 °C. A weight hourly space velocity (WHSV) of alkyl halide higher than 0.5 h ^"1 can be used, preferably between 1.0 and 10 h ^"1 , more preferably between 2.0 and 3.5 h ^"1 . The conversion of alkyl halide is carried out at a pressure less than 145 psig (1 MPa) and preferably less than 73 psig (0.5 MPa), or at atmospheric pressure (0.101 MPa). The conditions for olefin production can be varied based on the type of the reactor.

[0040] The methods and system disclosed herein can also include the ability to regenerate used/deactivated catalyst in a continuous process such as in a fluid catalytic cracking (FCC)- type process or reactor or a circulating catalyst bed process or reactor. The method and system can further include collecting or storing the produced olefin hydrocarbon product along with using the produced olefin hydrocarbon product to produce a petrochemical or a polymer. D. Catalyst Activity/Selectivity

[0041] Catalytic activity as measured by alkyl halide conversion can be expressed as the % moles of the alkyl halide converted with respect to the moles of alkyl halide fed. In particular aspects, the combined selectivity of ethylene and propylene is at least 70%, preferably at least 80%, more preferably at least 90%, or most preferably 90% to 98% (e.g., 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or more) under certain reaction conditions. The maximum combined space time yield (STY) of ethylene and propylene can be at least 1/hr, or 1/hr to 3/hr. The maximum conversion of alkyl halide can be at least 65% or 70% to 80%, 75%, 80%, 90%, or 100%. In certain instances, the selectivity of ethylene is about 40%) or higher and the selectivity of propylene is about 30% or higher. The maximum selectivity of ethylene can be 50% to 60% (e.g., 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%), 58%), 59%), 60%), or more) and the maximum selectivity of propylene is 35% to 45% (e.g., 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, or more).

[0042] As an example, chloromethane (CH ₃ C1) can be used define conversion and maximum selectivity of products by the following equations (IV)-(VIII):

(CH ₃ C1)° - (CH ₃ CI)

% CH ₃ CI Conversion = x 100, (IV)

(CH ₃ CI) ⁰ where, (CH3CI) ⁰ and (CH ₃ C1) are moles of methyl chloride in the feed and reaction product, respectively.

[0043] Maximum selectivity is defined as C-mole% and is defined for ethylene, propylene, and so on as follows:

2(C ₂ H ₄ )

% Ethylene Selectivity = x 100, (V)

(CH ₃ C1)° - (CH ₃ CI) where the numerator is the carbon adjusted mole of ethylene and the denominator is the moles of carbon converted.

[0044] Maximum selectivity for propylene may be expressed as:

3(C ₃ H ₆ )

% Propylene Selectivity = x 100, (VI)

(CH ₃ C1)° - (CH ₃ CI) where the numerator is the carbon adjusted mole of propylene and the denominator is the moles of carbon converted.

[0045] Maximum selectivity for butylene may be expressed as:

4(C ₄ H ₈ )

% Butylene Selectivity = x 100, (VII)

(CH ₃ C1) - (CH ₃ CI) where the numerator is the carbon adjusted mole of butylene and the denominator is the moles of carbon converted..

[0046] Selectivity for aromatic compounds may be expressed as: 6(C ₆ H ₆ ) + 7(C ₇ H ₈ ) + 8(C ₈ H ₁₀ )

% Aromatics Selectivity = x 100 (VIII)

(CH ₃ CI) - (CH ₃ CI)

E. Olefin Production System

[0047] Referring to FIG. 2, a system 10 is illustrated, which can be used to convert alkyl halides to olefin hydrocarbon products with the mixed-template SAPO-34 catalysts of the present invention. The system 10 can include an alkyl halide source 1 1, a reactor 12, and a collection device 13. The alkyl halide source 1 1 can be configured to be in fluid communication with the reactor 12 via an inlet 17 on the reactor. As explained above, the alkyl halide source can be configured such that it regulates the amount of alkyl halide feed entering the reactor 12. The reactor 12 can include a reaction zone 18 having the mixed- template SAPO-34 catalyst 14 of the present invention. The amounts of the alkyl halide feed 1 1 and the catalyst 14 used can be modified as desired to achieve a given amount of product produced by the system 10. Non-limiting examples of reactors that can be used include fixed-bed reactors, fluidized bed reactors, bubbling bed reactors, slurry reactors, rotating kiln reactors, or any combinations thereof when two or more reactors are used. In preferred aspects, reactor 12 is a fluid catalytic cracking (FCC)-type reactor or a circulating catalyst bed reactor that permits the regeneration of used/deactivated catalyst in a continuous process. The reactor 12 can include an outlet 15 for products produced in the reaction zone 18. The products produced can include ethylene, propylene and butylene. The collection device 13 can be in fluid communication with the reactor 12 via the outlet 15. Both the inlet 17 and the outlet 15 can be open and closed as desired. The collection device 13 can be configured to store, further process, or transfer desired reaction products (e.g., C2-C4 olefins) for other uses. By way of example only, FIG. 1 provides non-limiting uses of propylene produced from the catalysts and processes of the present invention. Still further, the system 10 can also include a heating source 16. The heating source 16 can be configured to heat the reaction zone 18 to a temperature sufficient (e.g., 325 to 375 °C) to convert the alkyl halides in the alkyl halide feed to olefin hydrocarbon products. A non-limiting example of a heating source 16 can be a temperature controlled furnace. Additionally, any unreacted alkyl halide can be recycled and included in the alkyl halide feed to further maximize the overall conversion of alkyl halide to olefin products. Further, certain products or byproducts such as butylene, C ₅₊ olefins and C ₂₊ alkanes can be separated and used in other processes to produce commercially valuable chemicals (e.g., propylene). This increases the efficiency and commercial value of the alkyl halide conversion process of the present invention.

EXAMPLES

[0048] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results. The materials used in the following examples are described in Table 1, and were used as-described unless specifically stated otherwise.

Table 1

EXAMPLE 1

(Preparation of Mixed-Template SAPO-34 Catalysts)

[0049] Catalyst 1 was synthesized using the following molar ratios 2TEAOH:0.4SiO ₂ : lAl ₂ O3: lP ₂ O ₅ :60H ₂ O. Aluminum isopropoxide was added slowly (over course of 30 mins) to a dilute solution of phosphoric acid under vigorous stirring. The slurry was allowed to stir for an additional 1 hour. Collodial silica was added drop-wise (over course of 15 mins) to the above slurry and the resulting mixture was stirred for 30 minutes. TEAOH was then added and the final mixture was stirred for 30 minutes. The slurry was added to a Teflon liner and placed in a 300 mL Parr autoclave. The sample was crystallized hydrothermally at 190 °C for 24 hours. After crystallization the product was washed with 400 mL DI water and separated by centrifugation. The solution was decanted and the washing was repeated 3 times. The final product was dried at 90 °C overnight, and then calcined in air at 550 °C for 8 hours. The material was confirmed to be SAPO-34 by X-ray Diffraction (XRD). [0050] Catalyst 2 was synthesized using the following molar ratios 1.59Morpholine:0.41TEAOH:0.4SiO ₂ : lAl ₂ O ₃ : lP ₂ O ₅ :60H ₂ O. Aluminum isopropoxide was added slowly (over course of 30 mins) to a dilute solution of phosphoric acid under vigorous stirring. The slurry was allowed to stir for an additional 1 hour. Collodial silica was added drop-wise (over course of 15 mins) to the above slurry and the resulting mixture was stirred for 30 minutes. Morpholine and TEAOH were then added and the final mixture was stirred for 30 minutes. The slurry was added to a Teflon liner and placed in a 300 mL Pan- autoclave. The sample was crystallized hydrothermally at 190 °C for 24 hours. After crystallization the product was washed with 400 mL DI water, and separated by centrifugation. The solution was decanted and the washing was repeated 3 times. The final product was dried at 90 °C overnight and then calcined at 550 °C for 8 hours. The material was confirmed to be SAPO-34 by XRD.

EXAMPLE 2

(Methyl chloride Conversion Reactions of Mixed-Template SAPO-34 Catalysts)

[0051] The mixed-template SAPO-34 catalyst 1 and 2 were tested for methyl chloride conversion by using a fixed-bed tubular reactor at about 450 °C for a period of 6 h. The catalyst powder was pressed, and then crushed and sized between 20 and 40 mesh screens. In each test, a fresh load of sized (20-40 mesh) catalyst (1.0 g) was loaded in a stainless steel tubular (1/2-inch outer diameter) reactor. The catalyst was dried at 200 °C under N ₂ flow (100 cm /min) for an hour and then temperature was raised to 450 °C at which time N ₂ was replaced by methyl chloride feed (100 cm ³ /min) containing 20 mol% CH ₃ C1 in N ₂ . The weight hourly space velocity (WHSV) of CH ₃ CI was about 0.8 h ^"1 to 3.0 h ^"1 and reactor inlet pressure was about 0 MPa. The SAR, percent CH ₃ C1 conversion, turn over frequency (TOF), C ₂ percent selectivity, C3 percent selectivity of the catalysts of present invention are listed in Table 2. Selectivities were based on methyl chloride and are carbon-based.

[0052] Table 2 below provides the CH ₃ C1 conversion and selectivity to C ₂ and C3 olefins at 5 h run time for the catalysts of the present invention.

Table 2

* Space Time Yield (Tonnes [C2+C3] / Tonnes Catalyst / hr)

[0053] From the examples shown above, Catalyst 2 having a mixed template of 1.59TEAOH : 0.41Morpholine had conversion, TOF, STY, and C ₂ -C ₃ selectivity results comparable to Catalyst 1 with TEAOH alone. Thus, a catalyst produced with more economical reagents can be used for alkyl halide to olefin reactions.