Process for converting saturated polyethylene to alkene products

Abstract

The present disclosure relates to a process for converting saturated polyethylene to at least alkene products. The process includes contacting saturated polyethylene with three or more catalyst components in a reactor, the reactor containing an alkene reactant. The three or more catalyst components include a metathesis catalyst component, an isomerization catalyst component, and a dehydrogenation catalyst component. By the contacting, at least a portion of the saturated polyethylene undergoes a dehydrogenation reaction to form unsaturated polyethylene, and at least a portion of the unsaturated polyethylene or a product derived therefrom undergoes a metathesis reaction and an isomerization reaction to produce an effluent containing at least alkene products.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the benefit of U.S. Provisional Application No. 63 / 353,320, filed Jun. 17, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to the chemical treatment of hydrocarbons. In particular, the present disclosure relates to a process for converting ethylene - containing materials, such as polyethylene, into smaller desired hydrocarbon products.

Background Art

[0003] Hydrocarbons are used or are starting materials for producing plastics, fuels, and various downstream chemicals for many industrial applications. Such hydrocarbons include alkenes such as ethene, propene, and butene (commonly also referred to as ethylene, propylene, and butylene respectively). Various production processes for these lower hydrocarbons have been developed, including petroleum cracking and various synthetic processes. Polyethylene (PE) is the most widely used plastic in the world and can be manufactured into a wide variety of products. However, a process for recycling polyethylene into smaller monomers such as propylene is desired. Conventional efforts for the chemical recycling of polyethylene have generally used pyrolysis and high - temperature pyrolysis. These processes are very energy - intensive and suffer from low selectivity of the desired products and the generation of greenhouse gases (e.g., CO2, CH4).

Summary of the Invention

[0004] Embodiments of the present disclosure address these and other needs by providing a process for converting polyethylene to alkene products. The processes described herein may enable three or more catalyst components within a reactor system to carry out multiple different chemical reactions, such as a combination of dehydrogenation, metathesis, and isomerization to produce alkene products from, for example, saturated polyethylene and alkene reactants.

[0005] According to one or more other aspects of the present disclosure, a process for converting saturated polyethylene to an alkene product having at least the chemical formula C m H 2m comprises contacting the saturated polyethylene in a reactor with three or more catalyst components, the reactor comprising an alkene reactant having the chemical formula C n H 2n wherein m is an integer from 3 to 20 and n is an integer from 2 to 20. The three or more catalyst components include a metathesis catalyst component, an isomerization catalyst component, and a dehydrogenation catalyst component. By the contacting, at least a portion of the saturated polyethylene undergoes a dehydrogenation reaction to form unsaturated polyethylene, and at least a portion of the unsaturated polyethylene or a product derived therefrom undergoes a metathesis reaction and an isomerization reaction to produce an effluent comprising at least an alkene product having the chemical formula C m H 2m

[0006] Additional features and advantages are described in the following "Detailed Description of the Invention", some of which will be readily apparent to those skilled in the art from that description, or will be recognized by practicing the embodiments described in the following "Detailed Description of the Invention" and the "Claims" included herein.

[0007] It should be understood that both the foregoing general description and the following detailed description are intended to provide an overview or framework for understanding the nature and characteristics of the claimed subject matter by describing various embodiments.

Brief Description of the Drawings

[0008]

Figure 1

[0009] To explain the simplified schematic diagram and description of FIG. 1, it does not include a number of valves, temperature sensors, electronic control devices, etc. that are used by those skilled in the art to operate specific chemical processes and may be well-known. Further, the accompanying components that are often included in typical chemical processing operations, carrier gas supply systems, pumps, compressors, furnaces, or other subsystems are not shown. It should be understood that these components are within the spirit and scope of the disclosed embodiments. However, operating components such as those described in the present disclosure may be added to the embodiments described in the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Some conventional processes for converting polyethylene to smaller products may use separate catalysts isolated in separate catalyst zones, such as by filling each of the separate catalysts into separate reactors, which can increase the initial capital cost of the reaction system. In contrast, the processes disclosed herein can enable tandem catalysis of polyethylene by contacting polyethylene with mutually compatible catalyst components to produce the desired alkene products. Catalytic depolymerization of polyethylene under mild reaction conditions provides an advantageous and sustainable alternative for the production of hydrocarbon feedstocks, monomers, or other useful chemicals.

[0011] Now, refer in detail to an embodiment of a process for converting saturated polyethylene to alkene products within a reactor. As used herein, "saturated polyethylene" has the chemical formula C x H 2x+2Refers to a compound containing, where x is an integer of at least 10 and the carbon-carbon bond is a single bond. In embodiments, the saturated polyethylene can include branched polyethylene. In embodiments, the saturated polyethylene can include linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), or a combination thereof. In embodiments, the saturated polyethylene has the chemical formula CH3(C2H4) x CH3 and can include compounds containing the same. In embodiments, the saturated polyethylene contains C x H 2x+2 , where x is an integer of 10 or more, 12 or more, or even 15 or more. In embodiments, the saturated polyethylene can have a number average molecular weight (M n ) of 150 g / mol to 1,000,000 g / mol. In embodiments, the saturated polyethylene can be a waste stream of a hydrocarbon treatment system or a product derived therefrom.

[0012] In embodiments, the reactor includes an alkene reactant. In embodiments, the alkene reactant has the chemical formula C n H 2n , where n is an integer from 2 to 20. For example, the alkene reactant can have the chemical formula C n H 2n , where n is an integer from 2 to 15, 2 to 10, 2 to 5, 2 to 4, or 2 to 3. In embodiments, the alkene reactant can include ethylene, propylene, butene, pentene, or a combination thereof. In embodiments, the alkene reactant can be selected from the group consisting of ethylene, propylene, butene, pentene, and combinations thereof. In embodiments, the alkene reactant can include ethylene. In embodiments, the alkene reactant can consist essentially of ethylene or consist of ethylene. In embodiments, the alkene reactant can include ethylene and butene. In embodiments, the alkene reactant can consist essentially of ethylene and butene or consist of ethylene and butene.

[0013] In an embodiment, the saturated polyethylene can be contacted with three or more catalyst components in a reactor. As used herein, "catalyst component" refers to any substance that accelerates the rate of a specific chemical reaction. The catalyst components described in the present disclosure and the catalyst compositions prepared using the catalyst components can be utilized to promote various reactions such as, but not limited to, dehydrogenation, metathesis, isomerization, or combinations thereof. In an embodiment, the catalyst composition can include at least one catalyst component, at least two catalyst components, or at least three catalyst components. As used herein, "catalyst composition" refers to solid fine particles containing at least one catalyst component. The catalyst composition can further include a catalyst carrier material.

[0014] In an embodiment, the catalyst components can include a dehydrogenation catalyst component, a metathesis catalyst component, and an isomerization catalyst component. Without being bound by a particular theory, it is believed that the dehydrogenation catalyst can introduce unsaturation into the carbon chain of the saturated polyethylene to produce unsaturated polyethylene. The metathesis catalyst can cleave the carbon chain of the unsaturated polyethylene in the presence of an alkene reactant to produce two products each having terminal unsaturation, and further metathesis of the terminal unsaturated polyethylene intermediate product by the alkene reactant can be non-productive for further cleaving the carbon chain. The isomerization catalyst component can convert terminal unsaturation to internal unsaturation, and it is believed that the isomerization product can be further decomposed into two products in the presence of the metathesis catalyst component and the alkene reactant. This cycle can continue until the desired product or group of products is produced from the process.

[0015] In an embodiment, the dehydrogenation catalyst component may be operable to convert saturated polyethylene to unsaturated polyethylene. In an embodiment, the dehydrogenation catalyst component can cause additional unsaturation along the polyethylene backbone in saturated polyethylene or a product derived therefrom. In an embodiment, the dehydrogenation catalyst component can cause the saturated polyethylene or a product derived therefrom to undergo transfer dehydrogenation. In an embodiment, the dehydrogenation catalyst component can include one or more elements selected from Groups 5 to 10 of the International Union of Pure and Applied Chemistry (IUPAC). In an embodiment, the dehydrogenation catalyst component can include platinum, iridium, ruthenium, rhenium, or a combination thereof. In an embodiment, the dehydrogenation catalyst component is selected from the group consisting of platinum, iridium, ruthenium, rhenium, and combinations thereof.

[0016] In an embodiment, the metathesis catalyst component in combination with an alkene reactant such as ethylene can function to cleave an unsaturated polyethylene chain into two species. In an embodiment, the metathesis catalyst component can decompose an alkene product derived from saturated polyethylene. In an embodiment, the metathesis catalyst component can include one or more elements selected from Groups 5 to 10 of the International Union of Pure and Applied Chemistry (IUPAC). In an embodiment, the metathesis catalyst component can include rhenium, ruthenium, tungsten, molybdenum, vanadium, or a combination thereof. In an embodiment, the metathesis catalyst component can be selected from the group consisting of rhenium, ruthenium, tungsten, molybdenum, vanadium, and combinations thereof. In an embodiment, the metathesis catalyst component can include methyltrioxorhenium (MTO).

[0017] In an embodiment, the isomerization catalyst component may be operable to move an unsaturation on unsaturated polyethylene or on a product derived therefrom from one position on the backbone to a different position. For example, in an embodiment, the isomerization catalyst component can move an unsaturation at a terminal position of unsaturated polyethylene to an internal position. In an embodiment, the isomerization catalyst component can include one or more elements selected from Groups 5 to 10 of the International Union of Pure and Applied Chemistry (IUPAC). In an embodiment, the isomerization catalyst component can include alumina, silica, iridium, palladium, ruthenium, or a combination thereof. In an embodiment, the isomerization catalyst component can be selected from the group consisting of alumina, silica, iridium, palladium, ruthenium, and combinations thereof. In an embodiment, the isomerization catalyst component can include modified alumina, modified silica, or a combination thereof. For example, in an embodiment, the isomerization catalyst component can include, but is not limited to, chlorinated alumina, γ-alumina, chlorinated silica, or a combination thereof. In an embodiment, the isomerization catalyst component can include [tert-butyl-POCOP]Ir[C2H4].

[0018] In an embodiment, the reactor may include one or more catalyst compositions including three or more catalyst components. For example, in an embodiment, the catalyst composition can include a metathesis catalyst component and an isomerization catalyst component. In an embodiment, the catalyst composition can include a dehydrogenation catalyst component and an isomerization catalyst component. In an embodiment, the catalyst composition can include a metathesis catalyst component and an isomerization catalyst component. In an embodiment, the catalyst composition can include a dehydrogenation catalyst component and a metathesis catalyst component. In an embodiment, the catalyst composition can include a dehydrogenation catalyst component, a metathesis catalyst component, and an isomerization catalyst component. In an embodiment, the catalyst composition can include a dehydrogenation catalyst component, a metathesis catalyst component, or an isomerization catalyst component. In an embodiment, the reactor can include a first catalyst composition including a metathesis catalyst component and an isomerization catalyst component. For example, in an embodiment, the reactor can include a first catalyst component, and the first catalyst component is MTO on alumina. In an embodiment, the reactor can include a second catalyst composition including a dehydrogenation catalyst component and an isomerization catalyst component. For example, in an embodiment, the reactor can include a second catalyst component, and the second catalyst component can include platinum on alumina or platinum on silica. In an embodiment, the first catalyst composition including MTO on alumina and the second catalyst composition including platinum on alumina can contact saturated polyethylene in the reactor. In other embodiments, the first catalyst composition including MTO on alumina and the second catalyst composition including [tert-butyl-POCOP]Ir[C2H4] can contact saturated polyethylene in the reactor.

[0019] In an embodiment, the catalyst composition is represented by the weight percentage of one or more elements selected from Groups 5-10 of the International Union of Pure and Applied Chemistry (IUPAC). In an embodiment, the first catalyst composition can include any one of the elements selected from Groups 5-10 of the IUPAC in an amount of 15 wt% or less based on the total weight of the first catalyst composition. For example, in an embodiment, the first catalyst composition can include any one of the elements selected from Groups 5-10 of the IUPAC in an amount of 12 wt% or less, 10 wt% or less, 8 wt% or less, 6 wt% or less, 4 wt% or less, or even 2 wt% or less based on the total weight of the first catalyst composition. In an embodiment, the first catalyst composition can include any one of the elements selected from Groups 5-10 of the IUPAC in an amount greater than 1 wt%, greater than 2 wt%, greater than 3 wt%, greater than 4 wt%, greater than 5 wt%, greater than 6 wt%, greater than 7 wt%, greater than 8 wt%, or even greater than 9 wt% based on the total weight of the first catalyst composition. In an embodiment, the first catalyst composition can include any one of the elements selected from Groups 5-10 of the IUPAC in an amount of 1 wt% to 15 wt%, 1 wt% to 12 wt%, 1 wt% to 10 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, 2 wt% to 15 wt%, 2 wt% to 12 wt%, 2 wt% to 10 wt%, 2 wt% to 5 wt%, 2 wt% to 4 wt%, 5 wt% to 15 wt%, 5 wt% to 12 wt%, or 5 wt% to 10 wt% based on the total weight of the first catalyst composition.

[0020] In an embodiment, the second catalyst composition can include any one of elements selected from IUPAC groups 5 to 10 in an amount of 15 wt% or less based on the total weight of the second catalyst composition. For example, in an embodiment, the second catalyst composition can include any one of elements selected from IUPAC groups 5 to 10 in an amount of 12 wt% or less, 10 wt% or less, 8 wt% or less, 6 wt% or less, 4 wt% or less, or even 2 wt% or less based on the total weight of the second catalyst composition. In an embodiment, the second catalyst composition can include any one of elements selected from IUPAC groups 5 to 10 in an amount of more than 1 wt%, more than 2 wt%, more than 3 wt%, more than 4 wt%, more than 5 wt%, more than 6 wt%, more than 7 wt%, more than 8 wt%, or even more than 9 wt% based on the total weight of the second catalyst composition. In an embodiment, the second catalyst composition can include any one of elements selected from IUPAC groups 5 to 10 in an amount of 1 wt% to 15 wt%, 1 wt% to 12 wt%, 1 wt% to 10 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, 2 wt% to 15 wt%, 2 wt% to 12 wt%, 2 wt% to 10 wt%, 2 wt% to 5 wt%, 2 wt% to 4 wt%, 5 wt% to 15 wt%, 5 wt% to 12 wt%, or 5 wt% to 10 wt% based on the total weight of the second catalyst composition.

[0021] It should be understood that, according to an embodiment, the catalyst composition can be produced by a method that results in a desired composition. Some non-limiting examples include incipient wetness impregnation, or vapor deposition of metal precursors (either essentially organic or inorganic), followed by their controlled decomposition.

[0022] In an embodiment, at least a portion of saturated polyethylene is dehydrogenated to form unsaturated polyethylene by contacting the saturated polyethylene with three or more catalyst components in a reactor containing an alkene reactant, and at least a portion of the unsaturated polyethylene or a product derived therefrom undergoes a metathesis reaction and an isomerization reaction to produce at least a chemical formula C m H 2mAn effluent containing an alkene product can be produced. For example, by contacting saturated polyethylene with a dehydrogenation catalyst component, the saturated polyethylene can be dehydrogenated, whereby at least one unsaturation is introduced into the polyethylene backbone to form unsaturated polyethylene. In an embodiment, the unsaturated polyethylene can be contacted with a metathesis catalyst component in the presence of an alkene reactant to cleave the unsaturated polyethylene to form two products, each product containing a terminal unsaturated polyethylene. The terminal unsaturated polyethylene can be contacted with an isomerization catalyst component to move the unsaturation from the terminal position to an internal position in the terminal unsaturated polyethylene to form internal unsaturated polyethylene. Without being bound by a particular theory, it is believed that the internal unsaturated polyethylene can undergo a further metathesis reaction by contacting it with a metathesis catalyst component in the presence of an alkene reactant. The product derived from the unsaturated polyethylene that is contacted with both the metathesis catalyst component and the isomerization catalyst component in the presence of an alkene reactant continues to circulate between the metathesis reaction and the isomerization reaction to produce smaller alkene products such as a compound of the chemical formula C m H 2m wherein m is an integer from 3 to 20 and is believed to be, for example, propylene. In an embodiment, increasing the reaction time allows additional metathesis and isomerization reaction cycles, so the reaction time can be increased to produce an effluent containing smaller alkene products.

[0023] In an embodiment, the reactor can be any reactor useful for causing polyethylene to contact with three or more catalyst components in the presence of an alkene reactant and allowing the catalytic reaction to proceed, such as a batch reactor, a fixed-bed reactor, a fluidized-bed reactor, a continuous stirred-tank reactor, a tubular plug-flow reactor, a reactive extruder, or a combination thereof. In an embodiment, two or more reactors, such as two or more reactors in series, can be used. In an embodiment, the reactor can include a reaction zone where contact and catalytic reaction can occur. In an embodiment, the three or more catalyst components can be present in the same reaction zone. In other embodiments, the reactor can include two or more reaction zones. In an embodiment, the reactor can include additional processing of reactants, such as processing of the alkene reactant, saturated polyethylene, and / or catalyst components. In an embodiment, the effluent containing one or more products from the catalytic reaction can be further processed, such as separation of one or more products from the effluent. For example, in an embodiment, propylene can be separated from the effluent.

[0024] In an embodiment, the pressure of the alkene reactant in the reactor, such as in the reaction zone during contact, can be from 0 pounds per square inch gauge (psig) to 3000 psig. For example, the pressure of the alkene reactant can be from 0 psig to 3000 psig, from 0 psig to 2000 psig, from 0 psig to 1000 psig, from 0 psig to 900 psig, from 0 psig to 800 psig, from 0 psig to 700 psig, from 0 psig to 600 psig, from 0 psig to 500 psig, or from 100 psig to 3000 psig. In some embodiments, the amount of the alkene reactant used can be quantified by the pressure of the alkene reactant in the reactor. In other embodiments, the amount of the alkene reactant can be quantified by the space velocity of the alkene reactant.

[0025] In an embodiment, the temperature of the reactor, such as the reaction zone during contact, can be 400 °C or lower. For example, the temperature of the reactor during contact can be 350 °C or lower, 300 °C or lower, 250 °C or lower, or even 200 °C or lower. In an embodiment, the temperature of the reactor during contact is 50 °C to 400 °C, 50 °C to 350 °C, 50 °C to 300 °C, 50 °C to 250 °C, 50 °C to 200 °C, 60 °C to 400 °C, 60 °C to 350 °C, 60 °C to 300 °C, 60 °C to 250 °C, or 60 °C to 200 °C. Without being bound by any particular theory, it is believed that a reduced reactor temperature, such as 400 °C or lower, 350 °C or lower, 300 °C or lower, 250 °C or lower, or 200 °C or lower, can reduce the formation of undesirable by-products during contact. Further, a decrease in the operating temperature of the reactor can reduce the energy required for the process, which can also reduce the economic cost of operation.

[0026] In an embodiment, the contact causes at least a portion of the saturated polyethylene to undergo a catalytic reaction to produce an effluent. In an embodiment, the effluent can include hydrocarbons having an average molecular weight of 40 g / mol to 1000 g / mol. In an embodiment, the effluent contains at least the chemical formula C m H 2m and can include alkene products. In an embodiment, the alkene product is a compound of the chemical formula C m H 2m wherein m is an integer from 3 to 20. For example, the alkene product can be a compound of the chemical formula C m H 2m wherein m is an integer from 3 to 15, 3 to 10, 3 to 8, 3 to 7, 3 to 6, 3 to 5, 3 to 4, or 3. In an embodiment, the alkene product can include propylene, butene, pentene, or a combination thereof. In an embodiment, the alkene product can be selected from the group consisting of propylene, butene, pentene, and combinations thereof. In an embodiment, the alkene product can consist essentially of or consist of propylene, butene, pentene, or a combination thereof. In an embodiment, the alkene product can consist essentially of or consist of propylene.

[0027] In an embodiment, the effluent can contain at least 1 wt%, at least 5 wt%, at least 10 wt%, at least 15 wt%, at least 20 wt%, at least 25 wt%, at least 30 wt%, at least 35 wt%, at least 40 wt%, at least 45 wt%, at least 50 wt%, at least 55 wt%, or even at least 60 wt% of alkene products.

Examples

[0028] Various aspects of the present disclosure are further clarified by the following examples. These examples are illustrative in nature and should not be understood as limiting the subject matter of the present disclosure. In Examples 1-7, a catalyst according to the present disclosure was prepared. The materials used in the examples are provided in Table 1.

[0029]

Table 1

[0030] In Examples 8 to 10, the catalytic process according to the present disclosure was carried out in a batch reactor. Hydrocarbons in the gas fraction product (C1 - C6) were quantitatively analyzed with a Shimadzu GC - 2010 gas chromatograph equipped with a capillary column (Supelco Alumina Sulfate plot, 30 m×0.32 mm) and a flame ionization detector (FID). The signal factor depends on the number of carbon atoms of each hydrocarbon species. The temperatures of the injector and the detector were set at 200 °C. The temperature - rising program was as follows: 90 °C (held for 3 minutes), rising to 150 °C at 10 °C / min (held for 20 minutes). Helium was used as the carrier gas. H2, C2H4, and C2H6 were quantified with a Shimadzu GC - 8AIT gas chromatograph equipped with a packed column (ShinCarbon ST 80 / 100, 2 m×2 mm) and a thermal conductivity detector (TCD). The linear response of the TCD signal to the injection amounts of H2, C2H4, and C2H6 was confirmed using a standard gas mixture. The response factor was obtained as the slope of the fitted line. The temperatures of the column, injector, and detector were set at 130 °C. The TCD current was 70 mA, and the carrier gas pressure was 300 kPa (N2). The liquid - phase product (>C5) was analyzed with an Agilent 6890N network gas chromatograph equipped with a DB - 5 column and an FID detector.

[0031] Example 1. Preparation of CH3ReO3 / Cl - Al2O3 Catalyst Composition 4 wt% of CH3ReO3 / Cl - Al2O3, which is the catalyst composition of Example 1, was synthesized using the following procedure. γ - Al2O3 (Strem Chemicals, Inc.) was calcined in air at 550 °C for 4 hours (h), and then evacuated at 450 °C overnight under dynamic vacuum (10 -4 Torr). This partially dehydrated and dehydroxylated alumina was chlorinated in a fixed - bed reactor at 300 °C for 1 hour in a CCl4 - saturated Ar stream (Airgas, UHP, 10 mL / min). CCl4 was distilled before use. The obtained Cl - Al2O3 was evacuated at 450 °C overnight, and then vacuum sublimated at room temperature (about 10 -4It was modified with CH3ReO3 (MTO, Sigma - Aldrich) under (Torr) to obtain a material containing 4 wt% MTO and 4 wt% Cl based on the total weight of the material. Periodically, the solid was shaken vigorously to promote uniform deposition of MTO. After grafting MTO onto Cl - Al2O3, the catalyst was evacuated at room temperature for 30 minutes to remove physically adsorbed materials, and the catalyst was stored in an N2 - filled glove box to prevent deactivation in air.

[0032] Example 2. Preparation of 1.5% Pt / γ - Al2O3 Catalyst Composition The catalyst composition of Example 2, 1.5% Pt / γ - Al2O3, was synthesized using the following procedure. γ - Al2O3 (Strem Chemicals, Inc., 186m 2 g -1 , pore volume 0.50 cm 3 g -1 ) was calcined in air at 500 °C for 4 hours and then evacuated at 450 °C for 12 hours (10 -4 Torr). Volatile trimethyl(cyclopentadienyl)platinum (32 ± 1 mg) was deposited onto dry alumina (1.300 ± 0.020 g) at room temperature by vacuum sublimation (about 10 -4 Torr) to obtain a material with 1.5 wt% Pt. During the procedure, the reactor was shaken vigorously to promote uniform deposition, and then evacuated at room temperature for 1 hour to remove physically adsorbed PtCp(CH3)3. The resulting solid was reduced in a H2 flow (4.0% in Ar, 30 mL / min) while raising the temperature at a rate of 2 °C / min to 250 °C. The material was held at this temperature for 2 hours and then cooled to room temperature and evacuated for 15 minutes. The reduced catalyst was stored in an N2 - filled glove box until use to avoid re - oxidation in air.

[0033] Example 3. Preparation of 1.5% Pt / Cl - Al2O3 Catalyst Composition The catalyst composition of Example 3, 1.5% Pt / Cl - Al2O3, was synthesized using the following procedure. γ - Al2O3 (Strem Chemicals, Inc., 186m 2 g -1 , pore volume 0.50 cm 3 g-1 ) was calcined in air at 500 °C for 4 hours. 1.5 g of the calcined alumina was impregnated with 0.6 mL of an aqueous solution containing 45.0 mg of Pt(NH3)4(NO3)2 and 46 mg of HCl (from concentrated HCl), and then dried in an oven at 80 °C for 2 hours and calcined in static air at 500 °C for 3 hours at a heating rate of 2 °C / min. Then, the obtained material was reduced at 280 °C for 2 hours under H2 (5.0% in Ar, 30 mL / min) at a heating rate of 2 °C / min, and then evacuated at about 10 -4 Torr at room temperature for 30 minutes. The reduced catalyst was stored in an N2-filled glove box until use to avoid re-oxidation in air.

[0034] Example 4. Preparation of 1.5% Pt / SiO2 Catalyst Composition The catalyst composition of Example 4, 1.5% Pt / SiO2, was synthesized using the following procedure. 1.5 g of the calcined SiO2 (Sylopol 952) was impregnated with 1.5 mL of an aqueous solution containing 45.0 mg of Pt(NH3)4(NO3)2, and then dried overnight in an oven at 80 °C and calcined in static air at 350 °C for 3 hours at a heating rate of 2 °C / min. Then, the obtained material was reduced at 280 °C for 2 hours under 5.0% H2 / Ar at a heating rate of 2 °C / min, and then evacuated at about 10 -4 Torr at room temperature for 30 minutes. The catalyst containing 1.5 wt% Pt was stored in an N2-filled glove box until use to avoid re-oxidation in air.

[0035] Example 5. Preparation of Re2O7 / γ-Al2O3 Catalyst Composition The Re2O7 / γ-Al2O3, which is the catalyst composition of Example 5, was synthesized using the following procedure. Re2O7 / γ-Al2O3 was prepared by incipient wetness impregnation of γ-Al2O3 (Strem Chemicals, Inc.) with ammonium perrhenate to obtain a material containing 10 wt% Re. Before impregnation, γ-Al2O3 was calcined at 550 °C for 4 hours within 2 hours. After impregnation, the dried material was activated by calcination in oxygen at 650 °C at a rate of 5 °C / min for 8 hours. The calcined catalyst was stored in an N2-filled glove box until use to avoid deactivation in air.

[0036] Example 6. Preparation of PtRe / SiO2 Catalyst Composition The PtRe / SiO2, which is the catalyst composition of Example 6, was prepared using the following procedure. PtRe / SiO2 was prepared by incipient wetness impregnation of silica powder with ammonium perrhenate to obtain a material containing 1 - 5 wt% Re. After impregnation, the material was calcined at 500 °C. Pt was deposited on the material by incipient wetness impregnation in toluene containing platinum acetylacetonate to obtain a material containing 1 - 5 wt% Pt. The resulting solid was dried in air at 120 °C for 4 hours, and then the temperature was raised to 210 °C over 4 hours. The material was reduced in H2 at 150 °C for 1 hour. The reduced catalyst was stored in an N2 atmosphere until use to avoid reoxidation in air. After the PtRe / SiO2 catalyst was calcined at 500 °C for 4 hours, it was reduced with H2 at 280 °C for 2 hours. The heating rate was 2 °C / min. After reduction, the catalyst was evacuated at room temperature for 30 minutes to remove physically adsorbed H2 and stored in an N2-filled glove box to prevent deactivation in air.

[0037] Example 7. tBu Preparation of [POCOP]Ir[C2H4] Catalyst Composition The catalyst composition of Example 7 tBuPOCOP]Ir[C2H4] was prepared according to "Catalytic Alkane Metathesis by Tandem Alkane Dehydrogenation-Olefin Metathesis", Science 2006, 312, 257-261. [C6H3-2,6-[OP(t-Bu)2]2]Ir[H][Cl] and NaO-t-Bu were weighed into an oven-dried Schlenk flask in a molar ratio of 1 to 1.2, respectively. Then, the solid was placed under a stream of argon. 40 mL of toluene was added to the flask via syringe, and the resulting suspension was stirred at room temperature for 10 minutes. Ethylene was bubbled into the solution for 1-2 hours. The solution was cannula-filtered through a pad of Celite, the volatile substances were evaporated under vacuum, and the resulting red solid was dried under vacuum overnight to obtain the product in a yield of 60%.

[0038] Example 8. Catalytic conversion of saturated polyethylene in a batch reactor to form alkenes In Example 8, saturated polyethylene was reacted with ethylene over the catalysts of Examples 2 and 5 in a 25 mL batch reactor (Parr reactor, series 4590). Inside an N2-filled glove box, 199 mg of Example 5, 199 mg of Example 2, and 120 mg of saturated polyethylene were charged into a 25 mL reactor equipped with a pressure gauge and a K-type thermocouple. Ethylene (99.999%, Airgas) was passed through a moisture / oxygen trap (Supelco) before use. Before introducing ethylene into the reactor, the residual air was purged three times from the gas line in 5-minute cycles. After pressurization, the total pressure was 40 bar. Reactor heating was started, and after reaching the desired temperature of 200 °C, the reaction time was tracked. After a reaction time of 24 hours, the reactor was cooled in an air stream. An aliquot of the gas from the reactor headspace was collected for GC analysis, and then the remaining headspace in the ventilation hood was evacuated. The remaining solid and liquid were transferred onto a fine glass filter (4.0 - 5.5 μm), filtered, and the insoluble substances were removed by washing with hot (50 °C) CHCl3. The soluble hydrocarbons were recovered by evaporating the solvent under reduced pressure (0.1 Torr). The insoluble substances containing hydrocarbons insoluble in the catalyst and hot CHCl3 were recovered from the filter. The results of the product formed in Example 8 of the present invention are shown in Table 2.

[0039]

Table 2

[0040] Example 9. Catalytic conversion of saturated polyethylene at various reaction times in a batch reactor to form alkenes In Example 9, according to Table 3, in a 10 mL batch reactor (Parr reactor, series 2500), saturated polyethylene was reacted with ethylene over the first catalyst composition (CC1) and the second catalyst composition (CC2). The reaction time was varied. Inside an N2-filled glove box, the first catalyst composition, the second catalyst composition, and saturated polyethylene were loaded into a Parr 2500 reactor equipped with a pressure gauge and a type J thermocouple. Argon at 28 psi was added as an internal standard. Ethylene (99.999%, Airgas) was passed through a moisture / oxygen trap (Supelco) before use. Before introducing ethylene into the reactor, the residual air was purged from the gas line three times in 5-minute cycles. Reactor heating was started, and after reaching the desired temperature set point of 200 °C, the reaction time was tracked. After the specified reaction time, the reactor was cooled in flowing air. An aliquot of the gas from the reactor headspace was taken for GC analysis, and then the remaining headspace in the ventilation hood was evacuated. The remaining solid and liquid were transferred onto a fine glass filter (4.0 - 5.5 μm), filtered, and the insoluble material was removed by washing with hot (50 °C) CHCl3. The soluble hydrocarbons were recovered by evaporating the solvent under reduced pressure (0.1 Torr). The insoluble material containing hydrocarbons insoluble in the catalyst and hot CHCl3 was recovered from the filter. The results of the products formed in Examples 9A, 9B, and 9C are shown in Table 4.

[0041]

Table 3

[0042]

Table 4

[0043] Example 10. Catalytic conversion of n-octadecane over various catalyst compositions in a batch reactor at various reaction times and reaction temperatures to form alkenes In Example 10, according to Table 5, n-octadecane was reacted with ethylene on two catalyst compositions in a batch reactor (Parr reactor, series 2500). Inside an N2-filled glove box, the first catalyst composition (CC1), the second catalyst composition (CC2), and n-octadecane were loaded into a 10 mL reactor (Parr 2500) equipped with a pressure gauge and a type J thermocouple. Ethylene (99.999%, Airgas) was passed through a moisture / oxygen trap (Supelco) before use. Before introducing ethylene into the reactor, the residual air was purged from the gas line three times in 5-minute cycles. Reactor heating was started, and after reaching the desired temperature set point, the reaction time was tracked. After the specified reaction time, the reactor was cooled in flowing air. Gas and liquid aliquots from the reactor headspace were taken for gas chromatography analysis using a flame ionization detector (GC-FID). The results of the products formed in Examples 10A - D and 10E - H are shown in Tables 6 and 7, respectively.

[0044]

Table 5

[0045]

Table 6

[0046]

Table 7

[0047] Example 11. Catalytic conversion of saturated polyethylene in a flow reactor to form alkenes In Example 11, a flow reactor as shown in Figure 1 was used. A 20 mL glass reaction sleeve (ID = 19.56 mm, OD = 22.15 mm) was placed in a 40 mL stainless steel stirred tank reactor (ID = 22.16 mm, OD = 40 mm), and the reactor was housed in an aluminum heating jacket. The temperature of the heating jacket was controlled by a hot plate and a thermocouple (IKA C-MAG HS7 digital). The reactor had two inlet ports, one for the liquid substrate and the other for the gaseous substrate. A Hamilton airtight syringe (5 mL) and a Kd Scientific Legato 100 Syringe Pump were used to deliver the liquid substrate to the apparatus. The gaseous substrate was supplied from a pressurized tank whose flow rate was set by an Alicat mass flow controller (MCS series). The outlet stream was led to an Equilibar back pressure regulator used to control the reaction pressure. An Agilent 6850 gas chromatograph (GC) was installed downstream of the regulator. The GC was equipped with a 6-port VICI-Valco gas sampling valve. The olefin formation rate was quantified using a continuous flow of ethylene as an internal standard. The stainless steel pipes and fittings were purchased from McMaster-Carr and Swagelok. The GC was equipped with an FID and a Petrocol DH capillary GC column (100 mm × 0.25 mm × 0.5 μm film thickness). The column was held at 45 PSI, and the gas sample was split 50:1. The column conditions and product elution times are shown in Table 8 and Table 9, respectively.

[0048]

Table 8

[0049]

Table 9

[0050] In an Ar-filled glove box, 249 mg of saturated polyethylene, 146 mg of Example 1, and 36.6 mg of Example 7 were loaded into a stirred tank reactor. After loading, the reactor was removed from the glove box, placed in an aluminum heating jacket, and connected to an ethylene delivery source. Using a continuous flow of ethylene supplied at 5 mL / min, the Ar atmosphere in the reactor was evacuated for at least 15 minutes. Ethylene gas (10.1 mL / min) was continuously flowed through the reactor for 19.5 hours, and the reactor was heated and maintained at 130 °C and 1 atm. To monitor the progress of the reaction, samples (0.25 mL) of the gaseous effluent were analyzed by GC every 34.2 minutes over the 19.5-hour reaction period. The results of Example 11 are shown in Table 10. The maximum propylene formation rate (R C3,max ) detected while the catalyst was operating was measured in millimoles per hour (mmol h -1 ). The maximum propylene selectivity (S C3 ,max) while the catalyst was operating was measured. The propylene formation rate is normalized by the cumulative olefin formation rate for a given reaction time. The average of the selectivities of propylene (S C3 , avg ) and butylene (S C4,avg ) was evaluated at each sampling point during the course of the continuous reaction for each species. The polyethylene conversion (weight percent) was also estimated by calculating the mass of polyethylene consumed per olefin produced according to Equation 1.

[0051]

Equation

[0052]

Table 10

[0053] It should be noted that one or more of the following claims utilize the terms "where" or "in which" as transitional phrases. For the purpose of defining the present technology, this term is introduced into the claims as an unrestricted transitional phrase used to introduce a list of a series of features of a structure and should be interpreted in the same way as the more commonly used unrestricted preamble term "comprising". For the purpose of defining the present technology, the transitional phrase "consisting of" can be introduced into the claims as a closed preamble term that limits the claims to the recited components or steps and any naturally occurring impurities. For the purpose of defining the present technology, the transitional phrase "consisting essentially of" can be introduced into the claims to limit one or more of the claims to the recited elements, components, materials, or method steps, and any unrecited elements, components, materials, or method steps that do not substantially affect the novel features of the claimed subject matter. The transitional phrases "consisting of" and "consisting essentially of" can be interpreted as a subset of non-limiting transitional phrases such as "comprising" and "including", and thus any use of a non-limiting phrase to introduce a list of a series of elements, components, materials, or steps should be interpreted as also disclosing a list of a series of elements, components, materials, or steps using the closed terms "consisting of" and "consisting essentially of". For example, a description of a composition "comprising" components A, B, and C should be interpreted as also disclosing a composition "consisting of" components A, B, and C, as well as a composition "consisting essentially of" components A, B, and C.Any quantitative value expressed in this application can be considered to include open - ended embodiments that coincide with the transitional phrase "comprising" or "including", as well as closed or partially closed embodiments that coincide with the transitional phrases "consisting of" and "consisting essentially of".

[0054] As used in this specification and the appended claims, the singular forms "a", "an", and "the" include the plural referents unless the context clearly dictates otherwise. The verb "comprises" and its conjugations should be interpreted to refer to elements, components, or steps non - exclusively. The referenced elements, components, or steps can be present, utilized, or combined with other elements, components, or steps that are not explicitly referenced.

[0055] It should be understood that any two quantitative values assigned to a property can constitute a range of that property, and all combinations of ranges formed from all the described quantitative values of a given property are contemplated in this disclosure. The subject matter of this disclosure has been described in detail with reference to specific embodiments. It should be understood that any detailed description of components or features of one or more embodiments does not necessarily mean that such components or features are essential to that particular embodiment or any other embodiment. Further, it should be apparent to those skilled in the art that various modifications and changes can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

Claims

1. Saturated polyethylene is at least chemical formula C ｍ H ２ｍ A process for converting to an alkene product, comprising contacting the saturated polyethylene with three or more catalyst components in a reactor, wherein the reactor is of chemical formula C ｎ H ２ｎ The alkene reaction product is included, During the ceremony, m is an integer between 3 and 20. n is an integer between 2 and 20. The three or more catalyst components include a metathesis catalyst component, an isomerization catalyst component, and a dehydrogenation catalyst component. Upon contact, at least a portion of the saturated polyethylene undergoes a dehydrogenation reaction to form unsaturated polyethylene, and at least a portion of the unsaturated polyethylene or products derived therefrom undergoes a metathesis reaction and an isomerization reaction to form at least one product of chemical formula C ｍ H ２ｍ A process that produces an effluent containing the aforementioned alkene product.

2. The process according to claim 1, wherein the pressure of the alkene reactant in the reactor during contact is between 0 pounds per square inch gauge (psig) and 3000 psig.

3. The process according to claim 1, wherein the temperature of the reactor during the contact is 400°C or less.

4. The process according to claim 1, wherein the alkene reactant comprises ethylene, propylene, butene, pentene, or a combination thereof.

5. The process according to claim 1, wherein the alkene product comprises propylene, butene, pentene, or a combination thereof.

6. The process according to claim 1, wherein the metathesis catalyst component comprises an element selected from Groups 5 to 10 of the International Union of Pure and Applied Chemistry (IUPAC).

7. The process according to claim 1, wherein the metathesis catalyst component includes rhenium, ruthenium, tungsten, molybdenum, vanadium, or a combination thereof.

8. The process according to claim 1, wherein the metathesis catalyst component comprises methyltrioxolenium (MTO).

9. The process according to claim 1, wherein the isomerization catalyst component comprises an element selected from Groups 5 to 10 of the IUPAC.

10. The process according to claim 1, wherein the isomerization catalyst component includes alumina, silica, iridium, palladium, ruthenium, or a combination thereof.

11. The process according to claim 1, wherein the dehydrogenation catalyst component comprises an element selected from Groups 5 to 10 of the IUPAC.

12. The process according to claim 1, wherein the dehydrogenation catalyst component includes platinum, iridium, ruthenium, rhenium, or a combination thereof.

13. The process according to claim 1, wherein the first catalyst composition comprises the metathesis catalyst component and the isomerization catalyst component, and the first catalyst composition comprises MTO on alumina.

14. The second catalyst composition comprises the isomerization catalyst component and the dehydrogenation catalyst component, wherein the second catalyst composition comprises platinum on alumina, platinum on silica, [tert-butyl-POCOP]Ir[C] ２ H ４ The process according to claim 1, including, or a combination thereof.

15. The process according to any one of claims 1 to 14, wherein a first catalyst composition comprising MTO on alumina and a second catalyst composition comprising platinum on alumina are in contact with the saturated polyethylene in the reactor.

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