Systems and methods for chromium catalyst activation

Abstract

Processes for producing activated chromium catalysts, such as chromium / silica catalysts and titanified chromium / silica catalysts, are disclosed and employ multi-step processes involving exposure to inert and oxidizing atmospheres under certain temperature conditions. The resulting activated chromium catalyst has surprisingly high melt index potential and is capable of producing ethylene-based polymers with lower gel count and higher melt index. Related activation systems are provided in which a fluidizing gas entering a fluidized bed vessel can be conditioned between an inert gas, an oxygen-containing gas, or a mixture of an inert gas and an oxygen-containing gas to minimize or prevent exotherm.

Description

Citation of relevant applications

[0001] This application was filed on November 7, 2024 as a PCT international patent application and claims the benefit and priority of U.S. Provisional Patent Application No. 63 / 597,370, filed on November 9, 2023, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0002] This disclosure generally relates to methods for activating supported chromium precatalysts and the use of activated chromium catalysts for polymerizing olefins. Background Technology

[0003] Supported chromium precatalysts are activated by exposing them to an oxygen-containing atmosphere (e.g., air) at high temperatures to convert at least a portion of the low-valent chromium to the +6 valent oxidation state (hexavalent chromium). However, in commercial practice, activation of large quantities of supported chromium catalysts typically results in relatively low Cr(VI) conversion, and the resulting activated chromium catalysts are generally inefficient for producing polymers with relatively high melt indexes and low membrane gel content. Furthermore, exposure to an oxygen-containing atmosphere can lead to significant exothermic reactions, which need to be controlled to prevent damage to the catalyst and the activation vessel. Overcoming these drawbacks with alternative methods of catalyst activation would be beneficial, and therefore, this invention is generally aimed at these objectives. Summary of the Invention

[0004] This summary is provided to introduce, in a simplified form, some concepts that will be further described below in the detailed embodiments. This summary is not intended to identify essential or necessary features of the claimed subject matter. Nor is it intended to limit the scope of the claimed subject matter.

[0005] Aspects of the present invention relate to a process for producing activated (or calcined) chromium catalysts, and one such process may include (1) exposing a pre-catalyst in a fluidized bed vessel to a feed cycle of a second oxidizing gas and a second inert gas at a temperature T2 ranging from 250℉ to 700℉ (121°C to 371°C) to a temperature T3 ranging from 700℉ to 950℉ (371°C to 482°C), and (2) heating the pre-catalyst to a temperature T4 ranging from 1000℉ to 1600℉ (538°C to 871°C) while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, and holding the pre-catalyst at T4 in the third inert gas or the third oxidizing gas for a holding time t1 ranging from 1 hour to 15 hours. The duration of each second oxidizing gas feed cycle is independently 10 seconds to 15 minutes, such as 20-30 seconds, and the duration of each second inert gas feed cycle is independently 10 seconds to 15 minutes, such as 4-5 minutes. The average duration of the second oxidizing gas feed cycle is less than the average duration of the second inert gas feed cycle, and the average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), such as 2℉ to 4℉ / min (1℃ to 2℃ / min).

[0006] Another process for producing the activated (or calcined) chromium catalyst described herein may include (1) exposing a pre-catalyst in a fluidized bed vessel to a feed of a first diluting oxidizing gas at a temperature T2 ranging from 250℉ to 700℉ (121℃ to 371℃) and at a temperature T3 ranging from 700℉ to 950℉ (371℃ to 510℃), and (2) heating the pre-catalyst to a temperature T4 ranging from 1000℉ to 1600℉ (538℃ to 871℃) while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, and holding the pre-catalyst at T4 in the third inert gas or the third oxidizing gas for a holding time t1 ranging from 1 hour to 15 hours. The first diluting oxidizing gas may contain 1 to 10% by volume oxygen, such as 3 to 6% by volume oxygen.

[0007] This document also provides olefin polymerization processes. These polymerization processes may include (I) performing any process to produce the activated chromium catalyst disclosed herein, and (II) contacting the activated chromium catalyst and optional co-catalyst with olefin monomers and optional olefin comonomers in a polymerization reactor system under polymerization conditions to produce olefin polymers.

[0008] Other aspects of the invention relate to activation systems, and such systems may include (a) a fluidized bed container having one or more heating zones and configured to fluidize and activate a supported chromium precatalyst; (b) one or more fluidizing gas inlets configured to introduce fluidizing gas into the fluidized bed container, the fluidizing gas comprising (i) an inert gas, (ii) an oxygen-containing gas, or (iii) a mixture of the inert gas and the oxygen-containing gas; (c) one or more thermocouples positioned inside the fluidized bed container for measuring an activation temperature inside the fluidized bed container; and (d) a controller configured to circulate the fluidizing gas between (i) the inert gas and (ii) the oxygen-containing gas, or to regulate (iii) the mixture of the inert gas and the oxygen-containing gas, based on time intervals and / or based on the activation temperature measured by the one or more thermocouples.

[0009] The foregoing summary and the following detailed description are illustrative and should not be construed as limiting. Furthermore, features or variations may be provided in addition to those set forth herein. For example, certain aspects may be addressed to various combinations and sub-combinations of features described in the detailed description. Attached Figure Description

[0010] The following figures form part of this specification and are included to further illustrate certain aspects of the invention. The invention can be better understood by referring to one or more of these figures in conjunction with the detailed description of the specific embodiments presented herein.

[0011] Figure 1 A catalyst activation system consistent with one aspect of this disclosure is shown.

[0012] Figure 2 A catalyst activation system consistent with another aspect of this disclosure is shown.

[0013] Figure 3 Representative temperature versus time graphs are shown for activation methods 1-5.

[0014] Figures 4-5 , Figures 6A-6B , Figures 7A-7B , Figures 8A-8B The activation methods 1-5 are shown. Figure 3 The graph shows the temperature versus time for the heat release process.

[0015] While the invention disclosed herein is readily adapted to various modifications and alternatives, only a few specific embodiments are illustrated by way of example in the accompanying drawings and described in detail below. The drawings and the detailed description of these specific embodiments are not intended to limit the breadth or scope of the inventive concept or the appended claims in any way. Rather, the drawings and detailed written description are provided to illustrate the inventive concept to those skilled in the art and to enable such persons to acquire and use the inventive concept.

[0016] definition To more clearly define the terms used herein, the following definitions are provided. Unless otherwise specified, the following definitions apply to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition in the IUPAC Chemical Terminology Compendium, 2nd Edition (1997) may be applied, provided that the definition does not conflict with any other disclosure or definition applied herein, or render any claim to which the definition applies ambiguous or invalid. If any definition or usage provided in any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein shall prevail.

[0017] In this document, the features of the subject matter are described such that combinations of different features are conceivable within a particular aspect. For each aspect and feature disclosed herein, all combinations are contemplated, whether explicitly described or not, that will not adversely affect the catalyst, composition, process, or method described herein. Furthermore, unless expressly stated otherwise, any aspect or feature disclosed herein may be combined to describe the catalyst, composition, process, or method of the invention consistent with this disclosure.

[0018] Generally speaking, elemental families use Chemical and Engineering News The numbering scheme indicated in the version of the periodic table published in 1985, 63(5), 27, indicates that a group of elements may be indicated by the common name assigned to that group; for example, alkali metals are indicated by Group 1 elements, alkaline earth metals by Group 2 elements, transition metals by Groups 3-12 elements, and halogens or halides by Group 17 elements.

[0019] Whenever used in this specification and claims, the term "hydrocarbon" refers to a compound containing only carbon and hydrogen, whether saturated or unsaturated. Other identifiers may be used to indicate the presence of a specific group in a hydrocarbon (e.g., a halocarbon indicates the presence of one or more halogen atoms that replace the same number of hydrogen atoms in the hydrocarbon). Non-limiting examples of hydrocarbons include alkanes (straight-chain, branched, and cyclic), alkenes (olefins), aromatic compounds, and other compounds.

[0020] For any particular compound or group disclosed herein, unless otherwise specified, any name or structure presented (generally or specifically) is intended to cover all conformational isomers, positional isomers, stereoisomers, and mixtures thereof that can be produced by a particular set of substituents. Unless otherwise specified, the name or structure (generally or specifically) also covers all enantiomers, diastereomers, and other optical isomers (if any), whether enantiomers or racemic forms, and mixtures of stereoisomers, as known to those skilled in the art. For example, general references to pentane include n-pentane, 2-methylbutane, and 2,2-dimethylpropane; and general references to butyl include n-butyl, sec-butyl, isobutyl, and tert-butyl.

[0021] Unless otherwise stated, the terms “contacting” and “exposing” are used herein to describe catalysts, compositions, processes, and methods in which materials or components are combined in any order, in any manner, and for any duration. For example, materials or components may be blended, mixed, slurried, dissolved, reacted, treated, impregnated, compounded, fluidized, or otherwise combined in some other manner or by any suitable method or technique.

[0022] As used herein, “BET surface area” refers to the area determined by the nitrogen adsorption Brunauer, Emmett, and Teller (BET) method according to ASTM D1993-91, and as in, for example, Brunauer, S., Emmett, PH, and Teller, E., “Adsorption of gases in multimolecular layers,” J. Am. Chem. Soc. ,60, 3, Surface area as described on pages 309-319.

[0023] The term "polymer" generally includes olefin homopolymers, copolymers, terpolymers, etc., as well as alloys and blends thereof. The term "polymer" also includes impact, block, graft, random, and alternating copolymers. Copolymers are derived from an olefin monomer and one olefin comonomer, while terpolymers are derived from an olefin monomer and two olefin comonomers. Thus, "polymer" encompasses copolymers and terpolymers derived from any olefin monomer and comonomer disclosed herein. Similarly, the scope of the term "polymerization" includes homopolymers, copolymers, and trimers. Therefore, ethylene polymers include ethylene homopolymers, ethylene copolymers (e.g., ethylene / α-olefin copolymers), ethylene terpolymers, etc., as well as blends or mixtures thereof. Thus, ethylene polymers encompass polymers commonly referred to in the art as LLDPE (linear low-density polyethylene) and HDPE (high-density polyethylene). As an example, olefin copolymers, such as ethylene copolymers, can be derived from ethylene and comonomers such as 1-butene, 1-hexene, or 1-octene. If the monomer and comonomer are ethylene and 1-hexene, respectively, the resulting polymer can be classified as an ethylene / 1-hexene copolymer. Unless otherwise stated, the term "polymer" also includes all possible geometries, and such geometries can include isotactic, syndiotactic, and random symmetry. Furthermore, unless otherwise stated, the term "polymer" is also intended to include polymers of all molecular weights.

[0024] In this disclosure, although catalysts, compositions, processes, and methods are described as “comprising” various components or steps, unless otherwise stated, the catalysts, compositions, processes, and methods may also be “substantially composed of various components or steps” or “composed of various components or steps.” Unless otherwise specified, the terms “an (a),” “an (an),” and “the” are intended to include multiple (a) alternatives, such as at least one (a).

[0025] This invention discloses several types of ranges. When any type of range is disclosed or claimed, it is intended to individually disclose or claim every possible number that such range can reasonably cover, including the endpoints of the range and any sub-ranges and combinations thereof covered therein. For example, in aspects of this invention, an oxidizing gas can have a range of oxygen contents. By disclosing that an oxidizing gas can contain 1 to 40 vol% oxygen, it is intended to state that the oxygen content can be any amount within the range, and can include, for example, any range or combination of ranges from 1 to 40 vol%, such as 1 to 30 vol%, 2 to 21 vol%, 3 to 25 vol%, or 4 to 10 vol% oxygen, etc. Similarly, all other ranges disclosed herein should be interpreted in a manner similar to this example.

[0026] Generally speaking, whether or not explicitly stated otherwise, quantities, dimensions, formulations, parameters, ranges, or other quantities or characteristics are “about” or “approximately”. Claims, whether modified by the terms “about” or “approximately”, include equivalents of quantities or characteristics.

[0027] Although any methods, apparatus, and materials similar to or equivalent to those described herein may be used in the practice or testing of this invention, typical methods, apparatus, and materials are described herein.

[0028] All publications and patents mentioned herein are incorporated herein in their entirety by reference for the purpose of describing and disclosing, for example, the constructs and methods described in the publications and patents, which may be used in conjunction with the inventions described herein. Detailed Implementation

[0029] The present invention generally relates to the conversion of low-valent supported chromium precatalysts into activated (hexavalent) chromium catalysts, which are then used in olefin polymerization processes.

[0030] One object of the present invention is to produce activated chromium catalysts with high Cr(VI) content and catalytic activity. Another object is to produce activated chromium catalysts with high melt index potential, enabling the production of ethylene-based polymers with lower molecular weights and / or higher melt flow rates. Another object is to produce activated catalysts with high melt index potential at relatively low calcination / activation temperatures. Another object is to produce activated chromium catalysts capable of producing ethylene-based polymers with a wide molecular weight distribution and low levels of long-chain branching. Another object is to produce activated chromium catalysts capable of producing ethylene-based polymers with extremely low levels of membrane gelation. Another object is to produce activated chromium catalysts capable of producing ethylene-based polymers with improved extrusion processability, suitable for a variety of applications, including blown films, pipes, and blow-molded products. Another object is to produce activated chromium catalysts without significant exothermic reactions during the activation process and with reduced emissions during the activation process. These and other benefits are described below.

[0031] Processes for activating chromium catalysts This document discloses a process for producing activated (or calcined) chromium catalysts. A first process may include (1) exposing a pre-catalyst in a fluidized bed vessel to a feed cycle of a second oxidizing gas and a second inert gas at a temperature T2 ranging from 250℉ to 700℉ (121℃ to 371℃) to a temperature T3 ranging from 700℉ to 950℉ (371℃ to 510℃), and (2) heating the pre-catalyst to a temperature T4 ranging from 1000℉ to 1600℉ (538℃ to 871℃) while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, and holding the pre-catalyst at T4 in the third inert gas or the third oxidizing gas for a holding time t1 ranging from 1 hour to 15 hours. The duration of each second oxidizing gas feed cycle is independently 10 seconds to 15 minutes (e.g., 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, 20 seconds to 2 minutes, or 20 seconds to 1 minute, etc.), and the duration of each second inert gas feed cycle is independently 10 seconds to 15 minutes (e.g., 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, or 20 seconds to 2 minutes, etc.). The average duration of the second oxidizing gas feed cycle is less than the average duration of the second inert gas feed cycle, and the average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min). While not wishing to be bound by theory, this first process is believed to reduce emissions during the activation / calcination process while minimizing or preventing exothermic reactions.

[0032] The second oxidizing gas in each cycle of step (1) may be the same or different, and may independently contain (or consist of, or consist of) the following: oxygen, air, a mixture of oxygen and an inert gas (e.g., nitrogen), a mixture of air and an inert gas (e.g., nitrogen), and any combination thereof. The second oxidizing gas in each cycle of step (1) may independently contain any suitable volume percentage of oxygen in the range of 1 to 40 vol%. In one aspect, the volume percentage of oxygen may be 1 to 30 vol%, in another aspect, the volume percentage of oxygen may be 2 to 21 vol%, and in yet another aspect, the volume percentage of oxygen may be 3 to 25 vol%, and in yet another aspect, the volume percentage of oxygen may be 4 to 10 vol%.

[0033] Similar to the second oxidizing gas in each cycle of step (1), the second inert gas in each cycle of step (1) may be the same or different. The second inert gas in each cycle of step (1) may independently contain (or consist of essentially, or consist of) the following: nitrogen, argon, or a combination thereof; alternatively, nitrogen; or alternatively, argon.

[0034] Utilize any suitable number of cycles of oxidizing and inert gases, for example, to control the exothermic reaction that occurs when the pre-catalyst is exposed to oxygen. While not limited thereto, the number of cycles in step (1) is typically 5 to 50, but more commonly, the number of cycles in step (1) is 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25, or 10 to 20 cycles.

[0035] The average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), but is not limited to this. Other suitable ranges for the average heating rate in step (1) include, for example, 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min). The heating rate can be controlled or adjusted by changing the relative duration of the oxidation feed cycle and the inert feed cycle.

[0036] A second process for producing activated (or calcined) chromium catalyst may include (1) exposing a pre-catalyst in a fluidized bed vessel to a feed of a first diluting oxidizing gas at a temperature T2 ranging from 250℉ to 700℉ (121℃ to 371℃) and a temperature T3 up to and including in the range of 700℉ to 950℉ (371℃ to 510℃), and (2) heating the pre-catalyst to a temperature T4 ranging from 1000℉ to 1600℉ (538℃ to 871℃) while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, and holding the pre-catalyst at T4 in the third inert gas or the third oxidizing gas for a holding time t1 ranging from 1 hour to 15 hours. The first diluting oxidizing gas may contain 1 to 10% by volume oxygen. While not wishing to be bound by theory, this second process is believed to also reduce emissions during the activation / calcination process while minimizing or preventing exothermic reactions.

[0037] Similar to the first process, any suitable heating rate can be used in step (1) of the second process, such as 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min). Other non-limiting ranges include 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min), etc. The heating rate can be controlled or adjusted by changing the volume % of oxygen present in the first diluting oxidizing gas.

[0038] Typically, the first diluted oxidizing gas in step (1) can contain any suitable volume percentage of oxygen in the range of 1 to 10 vol%. In one aspect, the volume percentage of oxygen can be 1 to 9 vol%, while in another aspect, the volume percentage of oxygen can be 1 to 8 vol%, and in yet another aspect, the volume percentage of oxygen can be 2 to 8 vol%, and in yet another aspect, the volume percentage of oxygen can be 2 to 7 vol%, and in yet another aspect, the volume percentage of oxygen can be 3 to 6 vol%. Therefore, in the second process, the pre-catalyst is exposed to the first dilute oxidizing gas; there is no contact with the inert gas stream alone during the exothermic elimination process, and there is no circulation between the inert gas stream and the oxidizing gas stream.

[0039] Generally, the features of the first and second processes are described independently herein, and these features may be combined in any combination to further describe the disclosed processes for producing activated chromium catalysts. Furthermore, unless otherwise stated, additional process steps may be performed before, during, and / or after any step in any process disclosed herein, and may be used without limitation and in any combination to further describe these processes. Moreover, any activated chromium catalyst produced according to the disclosed processes is within the scope of this disclosure and is covered herein. Activated chromium catalysts may also be referred to herein as calcined chromium catalysts.

[0040] Prior to step (1) of the first and second processes, a pre-catalyst may be loaded into a suitable fluidized bed vessel and then heated to T1 in a first inert gas. Therefore, the process disclosed herein may also include the steps of loading the pre-catalyst and heating it to T1 in a first inert gas prior to step (1). Prior to loading, the pre-catalyst may be at any suitable temperature, but is typically between ambient temperature and 120℉ (49°C), but is not limited thereto. Typically, temperature T1 is in the range of 400℉ to 700℉ (204°C to 371°C), such as 450℉ to 650℉ (232°C to 343°C) or 500℉ to 600℉ (260°C to 315°C).

[0041] Loading the precatalyst prior to step (1) can be achieved by loading the total amount of precatalyst into the vessel in portions of 1 to 10, 2 to 8, 3 to 10, or 3 to 6 before proceeding to step (1). The number of portions can depend on the size of the fluidized bed vessel and the amount of catalyst to be activated, as well as other considerations. During each portion of the total amount of precatalyst being loaded, the temperature is typically maintained between 300℉ and 600℉ (149°C to 315°C), such as 400℉ to 600℉ (204°C to 315°C). Loading each portion of the total amount of precatalyst is typically stopped when the temperature drops below 400℉ (204°C) or below 300℉ (149°C) (which is usually a result of moisture evaporation). Alternatively or alternatively, loading each portion of the total amount of precatalyst can be stopped when the pressure rises above 1 psig, which is also largely a result of moisture evaporation.

[0042] Although not limited to this, the total charge or total amount of the precatalyst may be at least 100 lb, at least 200 lb, at least 300 lb, at least 500 lb, at least 750 lb, at least 1000 lb, at least 1200 lb or at least 1500 lb, and typically up to and including 1750 lb, 2000 lb or 2500 lb.

[0043] Furthermore, prior to step (1) of the first and second processes, there may be a step to determine whether an exothermic temperature rise occurs in the fluidized bed vessel, and then proceed to step (1). One measure or indicator of an exothermic temperature rise is a temperature increase of at least 30℉ (17°C) in the fluidized bed reactor over a 5-minute time period. Another measure or indicator of an exothermic temperature rise is that the second derivative of the temperature (in the fluidized bed vessel) with respect to time is positive.

[0044] In step (1) of the first and second processes, temperature T2 is in the range of 250℉ to 700℉ (121℃ to 371℃), and temperature T3 is in the range of 700℉ to 950℉ (371℃ to 510℃). In one aspect, T2 may fall within the range of 400℉ to 600℉ (204℃ to 315℃), and in another aspect, T2 may be in the range of 600℉ to 700℉ (315℃ to 371℃), and in yet another aspect, T2 may be in the range of 500℉ to 650℉ (260℃ to 343℃), and in yet another aspect, T2 may be in the range of 625℉ to 700℉ (329℃ to 371℃), and in yet another aspect, T2 may be in the range of 575℉ to 675℉ (302℃ to 357℃). The temperature ranges disclosed herein are intended to cover cases where the corresponding steps in the process are performed at a range of different temperatures within the corresponding temperature range, rather than at a single fixed temperature. Similarly, in one aspect, T3 may fall within the range of 700℉ to 850℉ (371℃ to 454℃), and in another aspect, T3 may fall within the range of 700℉ to 800℉ (371℃ to 427℃), and in yet another aspect, T3 may fall within the range of 725℉ to 900℉ (385℃ to 482℃), and in yet another aspect, T3 may fall within the range of 750℉ to 950℉ (399℃ to 510℃), and in yet another aspect, T3 may fall within the range of 750℉ to 850℉ (399℃ to 454℃).

[0045] Referring now to step (2) of the first and second processes, while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, the precatalyst is heated to a temperature T4 in the range of 1000℉ to 1600℉ (538℃ to 871℃), and the precatalyst is held at T4 in the third inert gas or the third oxidizing gas for a holding time t1 in the range of 1 hour to 15 hours. Other representative and non-limiting ranges for t1 include 1 hour to 8 hours, 2 hours to 10 hours, 3 hours to 15 hours, 3 hours to 8 hours, or 4 hours to 6 hours, etc. Although not bound by theory, it is believed that high-temperature exposure to an inert atmosphere can dehydroxylate the catalyst without prematurely oxidizing chromium. Furthermore, it is believed that by using a relatively low T4 temperature, key polymer properties such as molecular weight distribution and low long-chain branching can be preserved.

[0046] Temperature T4 can be any suitable range from 1000℉ to 1600℉ (538℃ to 871℃). Representative and non-limiting ranges of T4 include 1000℉ to 1300℉ (538℃ to 704℃), 1100℉ to 1600℉ (593℃ to 871℃), 1100℉ to 1400℉ (593℃ to 760℃), 1100℉ to 1300℉ (593℃ to 704℃), or 1200℉ to 1300℉ (649℃ to 704℃), etc. Any suitable heating rate can be used in step (2) to achieve T4, and typical heating rates include 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min), etc.

[0047] The first and second processes may further include the following step: (3) while introducing a fourth inert gas into the fluidized bed vessel, cooling the pre-catalyst to a temperature T5 in the range of 900℉ to 1200℉ (482℃ to 649℃), provided that the temperature T5 is lower than the temperature T4. Any suitable cooling rate may be used in step (3), such as 1℉ to 4℉ / min (0.6℃ to 2.2℃ / min), 1.5℉ to 3.5℉ / min (0.8℃ to 2℃ / min), or 2℉ to 3℉ / min (1℃ to 1.7℃ / min), etc. In addition to the T5 range of 900℉ to 1200℉ (482℃ to 649℃), other temperature ranges may be used, such as the following non-limiting ranges: 900℉ to 1100℉ (482℃ to 593℃), 950℉ to 1150℉ (510℃ to 621℃), 1000℉ to 1200℉ (538℃ to 649℃), or 1000℉ to 1100℉ (538℃ to 593℃), etc.

[0048] After the fourth inert gas is introduced into the fluidized bed vessel and the temperature T5 is reached, the gas composition is optionally changed, and in step (4), the pre-catalyst can be exposed to the fourth oxidizing gas in the fluidized bed vessel at T5 for a holding time t2 ranging from 30 minutes to 10 hours. Typically, the holding time t2 is based on the amount of chromium present on the activated chromium catalyst sufficient to form at least 30 wt.%, and more often at least 50 wt.%, at least 70 wt.%, or at least 80 wt.% of chromium (VI) for a period of time. In step (4), the holding time t2 can range from 30 minutes to 10 hours, but other representative and non-limiting ranges for t2 include 30 minutes to 8 hours, 1 hour to 10 hours, 1 hour to 8 hours, 2 hours to 6 hours, or 3 hours to 5 hours, etc. There is generally a balance between chromium conversion and melt index potential, as longer t2 holding times and higher temperatures can reduce melt index potential.

[0049] The first and second processes may further include the following step: (5) cooling to a temperature T6 in the range of 500℉ to 700℉ (260℃ to 371℃) while introducing the fifth oxidizing gas into the fluidized bed vessel to produce an activated (calcined) chromium catalyst. Any suitable cooling rate may be used in step (5), such as 1℉ to 4℉ / min (0.6℃ to 2.2℃ / min), 1.5℉ to 3.5℉ / min (0.8℃ to 2℃ / min), or 2℉ to 3℉ / min (1℃ to 1.7℃ / min), etc. In addition to the T6 range of 500℉ to 700℉ (260℃ to 371℃), other temperature ranges can be used, such as the following non-limiting ranges: 500℉ to 650℉ (260℃ to 343℃), 550℉ to 700℉ (288℃ to 371℃), 550℉ to 650℉ (288℃ to 343℃), or 600℉ to 675℉ (315℃ to 357℃), etc. While not strictly required, temperature T6 is generally within 150℉ (83℃), 100℉ (56℃), 50℉ (28℃), 25℉ (14℃), or 10℉ (6℃) of temperature T1. Although not bound by theory, it is believed that changing to an inert atmosphere at relatively high temperatures impairs the conversion to Cr(VI).

[0050] Following step (5), the activated (calcined) chromium catalyst may undergo the following steps: (6) purging the activated (calcined) chromium catalyst in a fluidized bed vessel at T6 with a fifth inert gas and cooling to ambient temperature (nominally 77℉ or 25°C). While not limited thereto, in step (6), the activated (calcined) chromium catalyst may be purged with a fifth inert gas at T6 for a duration t3, typically ranging from 2 minutes to 20 hours; alternatively, 5 minutes to 12 hours; alternatively, 5 minutes to 5 hours; alternatively, 15 minutes to 4 hours; or alternatively, 30 minutes to 6 hours. While not bound by theory, it is believed that inert gas purging is important for removing oxygen / air from the catalyst pores to prevent oxygen / air from acting as a poison in the reactor during polymerization.

[0051] In the first and second processes for producing activated chromium catalysts, the first, third, fourth, and fifth inert gases may be the same or different. For example, in one aspect, the third inert gas is the same as the fourth inert gas, while in another aspect, the third inert gas is different from the fourth inert gas. The first, third, fourth, and fifth inert gases may independently comprise (or substantially consist of, or consist of) the following: nitrogen, argon, or a combination thereof; alternatively, nitrogen; or alternatively, argon.

[0052] Similarly, the first oxidizing gas, the third oxidizing gas, the fourth oxidizing gas, and the fifth oxidizing gas may be the same or different. For example, in one aspect, the third oxidizing gas is the same as the fourth oxidizing gas, while in another aspect, the third oxidizing gas is different from the fourth oxidizing gas. The first oxidizing gas, the third oxidizing gas, the fourth oxidizing gas, and the fifth oxidizing gas may independently contain (or substantially consist of, or consist of) the following: oxygen, air, mixtures of oxygen and inert gases (e.g., nitrogen), mixtures of air and inert gases (e.g., nitrogen), and any combination thereof. The first oxidizing gas, the third oxidizing gas, the fourth oxidizing gas, and the fifth oxidizing gas may independently contain any suitable volume percentage of oxygen in the range of 1 to 40 volume percentage. In one aspect, the volume percentage of oxygen may be 1 to 30 volume percentage, while in another aspect, the volume percentage of oxygen may be 2 to 21 volume percentage, and in yet another aspect, the volume percentage of oxygen may be 3 to 25 volume percentage, and in yet another aspect, the volume percentage of oxygen may be 4 to 10 volume percentage.

[0053] In this document, the fluidized bed vessel can be operated in batch or continuously, or any one or more steps of the process can be performed in batch or continuously. The amount of catalyst and the bed depth can be any amount and depth suitable for fluidized bed operation. In the first and second processes for producing activated chromium catalysts, the pre-catalyst (or activated catalyst) can be contacted with the gas stream in the fluidized bed vessel at any suitable linear velocity (typically in the range of 0.05 to 0.6 ft / sec). For example, each step in the disclosed process can be carried out by fluidizing the pre-catalyst (or, depending on the context, the activated catalyst) in an inert fluidizing gas (for an inert atmosphere) or an oxygen-containing fluidizing gas (for an oxidizing atmosphere) at a linear velocity of the gas stream independently in the range of 0.05 to 0.6 ft / sec, and in some respects 0.05 to 0.3 ft / sec or 0.1 to 0.4 ft / sec, and in other respects 0.2 to 0.5 ft / sec, 0.2 to 0.4 ft / sec, or 0.2 to 0.3 ft / sec.

[0054] The diameter of the fluidized bed container can be at least 12 inches, at least 20 inches, at least 30 inches, at least 40 inches or at least 50 inches, and typically up to and including 55 inches, 60 inches or 70 inches, but is not limited thereto.

[0055] The activated catalyst produced by the disclosed activation process possesses numerous superior properties compared to otherwise identical catalysts that have not undergone the specific steps described above. For example, the activated catalyst according to the invention can have a melt index potential greater than that of otherwise identical catalysts (commonly referred to as control catalysts) activated by exposure to an oxidizing gas at a temperature T4 for a duration t1 (e.g., at least 10%, at least 25%, at least 50%, at least 75%, or at least 100%). Alternatively, the control catalyst can be Magnapore, commercially available from WR Grace. ® The catalyst is calcined at 1200℉ (649℃) for 3 hours (for laboratory scale) or 8 hours (for large-scale). In making these comparisons, the polymerization reaction needs to be carried out under identical conditions. That is, the reaction temperature should be the same, the concentrations of ethylene and comonomers in the reaction zone should be the same, and the achieved productivity should also be the same, preferably in the range of 3000 gPE / gCat to 5000 gPE / gCat.

[0056] This potential for improved melt index can be achieved through melt index (MI, I2) or high-load melt index (HLMI, I2). 21(or both) can be used for measurement. For example, the activated catalyst of the present invention may have an MI potential of at least 0.2, at least 0.3, at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.9, at least 1, or at least 1.2 g / 10 min. Alternatively or additionally, when tested in isobutane at 105 °C, 550 psig ethylene up to 3000 g PE / gCat, the activated catalyst of the present invention may have an HLMI potential of at least 20, at least 25, at least 30, at least 35, at least 40, at least 50, at least 60, at least 70, at least 80, or at least 100 g / 10 min.

[0057] While the activated catalysts described herein can provide significant improvements in melt index potential, the resulting polymers can often be very similar to those produced using a control catalyst. Therefore, in some aspects, the activated catalysts according to the invention can produce polymers under standard polymerization conditions having an Mw / Mn ratio (or Mz / Mw ratio, or CY-a parameter) within 35% (or within 30%, 25%, 20%, 15%, 10%, or 5%) of the Mw / Mn ratio (or Mz / Mw ratio, or CY-a parameter) of the polymer produced using the control catalyst as defined above. The standard polymerization conditions are detailed in the following examples, but in summary, are isobutane diluent, a polymerization temperature of 105°C, an ethylene pressure of 550 psig, and the time required to achieve a productivity of 3000 g of polymer per g of catalyst.

[0058] Alternatively, the activated catalyst according to the invention can produce polymers under standard polymerization conditions that, depending on the context, have a Mw that is 30% (or 25%, or 20%, or 15% or 10% smaller) than that of polymers produced using a control catalyst as defined above when compared under the same or substantially the same MI (or HLMI).

[0059] Surprisingly, the activated catalyst according to the invention can produce polymers with a low amount of gel. In one aspect, the activated catalyst can produce polymers under standard polymerization conditions, the polymers having a gel content of [missing information - likely a specific value]. 2 A 25-micrometer-thick film contains less than or equal to 100 gels (and in some cases, per ft). 2The total membrane gel count (or catalyst particle gel count) of a 25-micron thick membrane (less than or equal to 80, less than or equal to 60, less than or equal to 40, less than or equal to 30, less than or equal to 20, less than or equal to 10, or less than or equal to 5 gels), where the membrane gels include those with a size greater than 200 μm (and for catalyst particle gel count, it is caused by catalyst particles).

[0060] Typically, the disclosed processes are applicable to activating any supported chromium precatalyst containing a silica support, thereby forming an activated chromium catalyst having at least a portion of chromium in a hexavalent oxidation state. Therefore, the supported chromium precatalysts considered herein encompass those prepared by contacting a silica support with a chromium-containing compound (chromium precursor, chromium source) and optionally a titanium-containing compound (titanium precursor, titanium source). The precatalyst may generally be referred to as a chromium / silica precatalyst, or, if titanium is used, a titanated chromium / silica precatalyst. The precatalyst can be formed by depositing a water-soluble chromium compound (and a water-soluble titanium compound, if used) onto a pre-formed silica in the form of an aqueous slurry, followed by spray drying of the slurry to form the precatalyst. The precatalyst can also be formed by depositing a water-soluble titanium compound onto a pre-formed silica already containing the desired chromium in the form of an aqueous slurry, followed by spray drying of the slurry to form the precatalyst.

[0061] While not limited to these, typical titanium compounds used include titanium carboxylate, which may also contain nitrogen compounds to help adjust pH. The carboxylate can be a dicarboxylic acid or tricarboxylic acid and an α-hydroxy monocarboxylic acid, examples of which include oxalic acid, citric acid, malic acid, lactic acid, glycolic acid, gluconic acid, 2-hydroxybutyric acid, glyoxylic acid, malonic acid, phosphonoacetic acid, tartaric acid, etc. Suitable nitrogen compounds include simple alkylamines, alkanolamines, cyclic amines and more complex polynitrogen compounds, as well as amides and quaternary ammonium hydroxides. Examples include dimethylformamide (DMF), acetamide, acrylamide, allylamine, ammonia, methylamine, diethylamine, ethanolamine, diethanolamine, butylamine, tert-butylamine, N,N'-dibutylurea, tetraethylammonium hydroxide, ammonium hydroxide, dimethylethanolamine, creatine, creatine anhydride, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), diethylhydroxyamine, diisopropanolamine, dimethylaminoethanol, dimethyl carbamate, dimethyl... Examples of chromium compounds include methylformamide, dimethylglycine, dimethylisopropanolamine, N,N'-dimethylurea, ethylamine, ethylene glycolamine, hexylamine, hydroxylamine, imidazole, isopropanolamine, methacrylamide, N-methylaniline, N-methyl-2-propanolamine, methyldiethanolamine, methylformamide, propylamine, 2-propanolamine, pyrazole, pyrrolidine, pyrrolidone, succinimide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, triethanolamine, triisopropanolamine, trimethylamine, and urea. Typical chromium compounds include chromium acetate(III), basic chromium acetate(III), chromium formate(III), Cr₂O₃, Cr(OH)₃, and Cr(NO₃)₃. Chromium compounds are typically trivalent, but hexavalent chromium compounds are also suitable, provided they are subsequently reduced to their trivalent form during catalyst manufacturing. The silica used in this invention can be any suitable pre-prepared silica dry gel with an acceptable porosity, the grade of which is available from Asahi Glass and Grace (e.g., HA30W). While not limited thereto, silica with a surface area of ​​300 to 500 m² is conveniently used. 2 / g, pore volume of 1.5 to 2.0 m³ 2 Silica with a d50 average particle size of 30 to 130 micrometers (e.g., approximately 1.6 mL / g) and a d50 average particle size of 30 to 130 micrometers (e.g., 40 to 70 micrometers). Additional information regarding precatalysts that can be activated as described herein and methods for preparing said precatalysts is provided in representative U.S. Patent Nos. 10,300,460, 10,323,109, 10,513,570, 10,543,480, 10,722,874, 10,858,456, 10,889,664, and 11,242,416.

[0062] Chromium polymerization catalysts typically require supports with relatively high porosity to allow for catalyst fragmentation and subsequent detachment of polymer chains from the fragments, some of which are hundreds of times longer than the catalyst's pore size. Therefore, the total pore volume of the pre-catalyst (or silica support, or activated chromium catalyst) is typically in the range of 0.5 to 5 mL / g, and more commonly in the range of 1 to 5 mL / g, 1 to 3 mL / g, or 1.5 to 2 mL / g, etc. The BET surface area of ​​the pre-catalyst (or silica support, or activated chromium catalyst) is not limited to any particular range, but is typically in the range of 100 to 700 m². 2 / g, such as 200 to 600 m 2 / g, 250 to 550m 2 / g or 300 to 500 m 2 Within the range of / g, etc.

[0063] The precatalyst, silica support, and activated chromium catalyst can have any suitable shape or form, and this can depend on the type of polymerization process in which the chromium catalyst is used. However, in general, the precatalyst, silica support, and activated chromium catalyst have relatively small particle sizes, with representative ranges for the average (d50) particle size of the precatalyst (or silica support, or activated chromium catalyst) including, but not limited to, 10 to 500 micrometers, 15 to 250 micrometers, 30 to 130 micrometers, or 40 to 70 micrometers.

[0064] Referring to both the first and second processes, the precatalyst (or activated catalyst) comprises a silica support and 0.1 to 5 wt.% chromium. Other suitable ranges for the amount of chromium present on the precatalyst (or activated chromium catalyst) include, but are not limited to, 0.1 to 4 wt.%, 0.2 to 5 wt.%, 0.5 to 3 wt.%, 0.5 to 2 wt.%, or 0.5 to 1.5 wt.% chromium. These weight percentages are based on the amount of chromium relative to the total weight of the precatalyst or activated chromium catalyst.

[0065] There is no particular limitation on the amount of chromium in the precatalyst (before activation) in an oxidation state of +5 or lower. The amount of chromium in the precatalyst in an oxidation state of +5 or lower is at least 50 wt.%, and more typically at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.%. This percentage is based on the amount of chromium in the precatalyst in an oxidation state of +5 or lower relative to the total amount of chromium on the precatalyst.

[0066] Conversely, at least 40 wt.% of the chromium in the activated chromium catalyst is present in the hexavalent oxidation state after the activation step, and more typically at least 50 wt.% of the chromium is present as chromium (VI). In other respects, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.% of the chromium in the activated chromium catalyst may be present in the +6 oxidation state. These weight percentages are based on the total amount of chromium present on the activated chromium catalyst. Conventional chromium (VI) catalysts will typically be orange, yellow, or brownish-red to indicate the presence of chromium (VI).

[0067] Referring to both the first and second processes, the precatalyst (or activated chromium catalyst) may comprise a silica support, 0.1 to 5 wt.% chromium, and 0.1 to 10 wt.% titanium (if present). Other suitable ranges for the amount of titanium present on the precatalyst (or activated chromium catalyst) include, but are not limited to, 0.5 to 10 wt.%, 1 to 10 wt.%, 2 to 8 wt.%, or 2 to 6 wt.% titanium. These weight percentages are also based on the amount of titanium relative to the total weight of the precatalyst or activated catalyst.

[0068] The precatalyst (or activated chromium catalyst) may also contain nitrogen from the nitrogen-containing compound used to prepare the precatalyst. Typically, the precatalyst (or activated chromium catalyst) contains 1 to 5 moles of nitrogen per mole of titanium, and more often, 1 to 4.5, 1.5 to 5, 1.5 to 4.5, 2 to 5, 2 to 4, or 2 to 3 moles of nitrogen per mole of titanium.

[0069] The precatalyst can also be characterized by the presence of carboxylate groups / ligands before activation and the amount of carbon. In one aspect, the precatalyst may contain 1 to 5 moles of carboxylate per mole of titanium; in another aspect, 1 to 4 moles of carboxylate per mole of titanium; in yet another aspect, 1 to 3 moles of carboxylate per mole of titanium; in another aspect, 1.5 to 5 moles of carboxylate per mole of titanium; in yet another aspect, 1.5 to 4 moles of carboxylate per mole of titanium; and in yet another aspect, 2 to 3 moles of carboxylate per mole of titanium. Examples of carboxylate (including dicarboxylate) include acetates, oxalates, citrates, malates, lactates, gluconates, glycolates, 2-hydroxybutyrates, glyoxylates, lactates, malates, malonates, phosphonoacetates, tartrates, etc.

[0070] Alternatively, the precatalyst may contain 0.5 to 10 wt.% carbon prior to activation, and more often, 1 to 10 wt.%, 1 to 5 wt.%, 2 to 10 wt.%, 2 to 8 wt.%, or 2 to 6 wt.% carbon. These weight percentages are based on the amount of carbon relative to the weight of the precatalyst.

[0071] The precatalysts in the first and second processes can be activated individually, or optionally in the form of a blend or mixture with a second precatalyst having a different catalyst composition. Any relative amount of the precatalyst and the second precatalyst in step (1) can be used. For example, the second precatalyst can be a chromium / silica precatalyst; alternatively, a chromium / silica-titanium dioxide cogel precatalyst; or alternatively, a chromium oxide-silica-titanium dioxide ternary gel precatalyst.

[0072] Activation system The catalyst activation system according to this disclosure may include (a) a fluidized bed container having one or more heating zones and configured to fluidize and activate a supported chromium precatalyst; (b) one or more fluidizing gas inlets configured to introduce fluidizing gas into the fluidized bed container, the fluidizing gas comprising (i) an inert gas, (ii) an oxygen-containing gas, or (iii) a mixture of the inert gas and the oxygen-containing gas; (c) one or more thermocouples positioned inside the fluidized bed container for measuring an activation temperature inside the fluidized bed container; and (d) a controller configured to circulate the fluidizing gas between (i) the inert gas and (ii) the oxygen-containing gas, or to regulate (iii) the mixture of the inert gas and the oxygen-containing gas, based on time intervals and / or based on the activation temperature measured by the one or more thermocouples.

[0073] Similar to the first and second processes described above for producing activated chromium catalysts, the inert gas used in the activation system may comprise (or consist substantially of, or consist of) nitrogen, argon, or combinations thereof; alternatively, nitrogen; or alternatively, argon. Similarly, the oxygen-containing gas used in the activation system may comprise (or consist substantially of, or consist of) oxygen, air, mixtures of oxygen and inert gases (e.g., nitrogen), mixtures of air and inert gases (e.g., nitrogen), and any combination thereof. The oxygen-containing gas may contain any suitable volume percentage of oxygen in the range of 1 to 40 vol%. In one aspect, the volume percentage of oxygen may be 1 to 30 vol%, in another aspect, the volume percentage of oxygen may be 2 to 21 vol%, and in yet another aspect, the volume percentage of oxygen may be 3 to 25 vol%, and in yet another aspect, the volume percentage of oxygen may be 4 to 10 vol%.

[0074] The supported chromium precatalyst processed in the fluidized bed vessel and activation system can also possess any of the characteristics and properties of the precatalysts described above with respect to the first and second processes. Therefore, the supported chromium precatalyst can have any total pore volume in the range of 0.5 to 5 mL / g and a porosity in the range of 100 to 700 m³. 2 Any BET surface area in the range of / g and any d50 particle size in the range of 10 to 500 micrometers. Similarly, the supported chromium precatalyst comprises a suitable support (e.g., silica) and any amount of chromium in the range of 0.1 to 5 wt.% and optionally any amount of titanium in the range of 0.1 to 10 wt.% of titanium. These weight percentages are based on the total weight of the supported precatalyst.

[0075] The fluidized bed container of the activation system contains one or more heating zones, and therefore the fluidized bed container can have two or more heating zones, such as two heating zones, three heating zones, four heating zones, etc. If desired, the heating zones can have independent temperature control. Similarly, the activation system contains one or more thermocouples, and therefore the system can have two or more thermocouples, such as two thermocouples, three thermocouples, four thermocouples, etc. There is no particular limitation on the number of thermocouples that can be positioned within the fluidized bed container to measure the dominant activation temperature within the container.

[0076] While the activation system of the present invention is not limited to methods for introducing fluidizing gas (or multiple gases) into a fluidized bed container, in one aspect, one or more fluidizing gas inlets may include an inert gas inlet line and an oxygen-containing gas inlet line. In this regard, the controller may be further configured to circulate between (1) introducing inert gas into the fluidized bed container through the inert gas inlet line by opening a first valve on the inert gas inlet line and closing a second valve on the oxygen-containing gas inlet line, and (2) introducing oxygen-containing gas into the fluidized bed container through the oxygen-containing gas inlet line by opening the second valve and closing the first valve. In another aspect, one or more fluidizing gas inlets may include a single fluidizing gas inlet. In this regard, the controller may be further configured to circulate between (1) introducing inert gas into the fluidizing gas inlet through the inert gas inlet line by opening a first valve on the inert gas inlet line and closing a second valve on the oxygen-containing gas inlet line, and (2) introducing oxygen-containing gas into the fluidizing gas inlet through the oxygen-containing gas inlet line by opening the second valve and closing the first valve.

[0077] In these respects, the controller may be further configured to adjust the duration of the feed inert gas independently within a range of 10 seconds to 15 minutes (e.g., 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, or 20 seconds to 2 minutes, etc.) and the duration of the feed oxygen-containing gas independently within a range of 10 seconds to 15 minutes (e.g., 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, 20 seconds to 2 minutes, or 20 seconds to 1 minute, etc.). Alternatively or additionally, the controller may be further configured to adjust the average duration of the feed inert gas, said average duration being greater than the average duration of the feed oxygen-containing gas.

[0078] Alternatively, the controller may be further configured to adjust any suitable number of cycles for the introduction of an inert gas followed by an oxygen-containing gas, for example, to control the exothermic reaction that occurs when the pre-catalyst is exposed to oxygen. While not limited thereto, the number of cycles is typically 5 to 50, but more often, it is 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25, or 10 to 20.

[0079] Alternatively, the controller may be further configured to regulate the circulation of the inert gas and the oxygen-containing gas to maintain an average increase in activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min) within a temperature range from the lower end of 250℉ to 700℉ (121℃ to 371℃ / min) to the higher end of 700℉ to 950℉ (371℃ to 510℃ / min). Other suitable ranges for the average heating rate include, for example, 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0080] As described above, while the activation system of the present invention is not limited to methods for introducing fluidizing gas (or multiple gases) into a fluidized bed container, in another aspect, one or more fluidizing gas inlets may comprise a single fluidizing gas inlet. In this regard, the controller may be further configured to regulate the mixture of inert gas and oxygen-containing gas in the fluidizing gas inlet by controlling (or metering) a first flow rate of inert gas entering the fluidizing gas inlet through an inert gas inlet line and a second flow rate of oxygen-containing gas entering the fluidizing gas inlet through an oxygen-containing gas inlet line.

[0081] In this respect, the controller can be further configured to control the relative amounts of inert gas and oxygen-containing gas in the mixture at any suitable oxygen volume percentage, for example, to control the exothermic reaction that occurs when the pre-catalyst is exposed to oxygen. While not limited thereto, the amount of oxygen is typically 1 to 10 vol%, but more often, 1 to 8 vol%, 2 to 8 vol%, 2 to 7 vol%, or 3 to 6 vol% oxygen is used in the mixture.

[0082] Alternatively, the controller may be further configured to regulate the mixture of inert gas and oxygen-containing gas (e.g., to contain any suitable volume percentage of oxygen) to maintain an average increase in activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min) within a temperature range from the lower end of the range of 250℉ to 700℉ (121℃ to 371℃ / min) to the higher end of the range of 700℉ to 950℉ (371℃ to 510℃ / min). Other suitable ranges for the average heating rate include, for example, 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min), etc.

[0083] As described herein, the controller is configured to circulate the fluidizing gas between (i) an inert gas and (ii) an oxygen-containing gas, or to regulate (iii) a mixture of inert gas and oxygen-containing gas, based on time intervals and / or based on an activation temperature measured by one or more thermocouples. In one aspect, the controller may be further configured to determine an exothermic increase in the activation temperature measured by one or more thermocouples. In this respect, an exothermic increase is considered to be a temperature rise of at least 30℉ (17°C) within 5 minutes. Additionally or alternatively, the controller may be further configured to determine an exothermic increase in the activation temperature measured by one or more thermocouples, and in this case, the presence of exothermicity can be determined by the positive second derivative of temperature with respect to time (acceleration of temperature with respect to time). Thus, the controller can determine when exothermicity occurs, and then, in some aspects, circulate the fluidizing gas between (i) an inert gas and (ii) an oxygen-containing gas by increasing the inert gas injection relative to the oxygen-containing gas injection to minimize or eliminate the exothermicity, and in other aspects, regulate (iii) the mixture of inert gas and oxygen-containing gas to contain a lower volume % of oxygen, thereby minimizing or eliminating the exothermicity.

[0084] In this document, the activation system can be operated in batches or continuously, or any one or more components of the system (e.g., the fluidized bed vessel within the system) can be operated in batches or continuously. Any suitable fluidizing gas velocity can be used in the fluidized bed vessel. Typically, one or more fluidizing gas inlets are configured to introduce fluidizing gas into the fluidized bed vessel at a linear velocity of 0.05 to 0.6 ft / sec. Other suitable ranges include, but are not limited to, 0.05 to 0.3 ft / sec, 0.1 to 0.4 ft / sec, 0.2 to 0.5 ft / sec, 0.2 to 0.4 ft / sec, or 0.2 to 0.3 ft / sec.

[0085] Now for reference Figure 1 This illustrates a catalyst activation system 100 consistent with aspects of this disclosure. The activation system 100 includes a fluidized bed container 110, heating zones 112 and 118, a thermocouple 120, fluidized catalyst particles 125, a gas inlet line 165, a gas distribution plate 170, and a controller 190. Figure 1 In this system, an inert gas (e.g., nitrogen) is supplied from an inert gas source 130 through an inert inlet line 135 to a gas inlet line 165. The inert gas flows through an inert gas valve 140 (when valve 140 is open) into the gas inlet line 165, and then flows through a gas distribution plate 170 in the fluidized bed container 110, wherein the gas flow direction 175 is upward through the fluidized bed container 110.

[0086] Similarly, Figure 1 Oxygen-containing gas (e.g., air) is supplied from oxygen source 150 through oxygen inlet line 155 to gas inlet line 165. The oxygen-containing gas flows through oxygen valve 160 (when valve 160 is open) into gas inlet line 165 and subsequently flows through gas distribution plate 170 in fluidized bed container 110, with the gas flow direction 175 upward through fluidized bed container 110. Effluent treatment 180 is provided at the top outlet of fluidized bed container 110, and this may include filtration devices for removing catalyst particles and mechanisms for recirculating the fluidized gas.

[0087] exist Figure 1Information or data 185 regarding parameters within the activation system 100 (such as the activation temperature in the fluidized bed vessel 110 measured by thermocouple 120) can be provided to controller 190, which can then control or regulate any component or operating variable within the activation system 100. For example, controller 190 can circulate between introducing inert gas into gas inlet line 165 through inert gas inlet line 135 by opening inert gas valve 140 and closing oxygen valve 160, and introducing oxygen-containing gas into gas inlet line 165 through oxygen inlet line 155 by opening oxygen valve 160 and closing inert gas valve 140. Thus, if information or data 185 from thermocouple 120 indicates a rapid increase in activation temperature in fluidized bed vessel 110 (e.g., exothermic), controller 190 can open inert gas valve 140 and close oxygen valve 160, thereby reducing the rate of temperature increase.

[0088] In the above Figure 1 In a variant where the inert gas valve 140 and oxygen valve 160 are metering valves, a mixture of inert gas and oxygen-containing gas can be introduced into the fluidized bed container 110 through the gas inlet line 165. The controller 190 can adjust the relative amount of inert gas flowing through the inert gas (metering) valve 140 in the inert gas inlet line 135 and the relative amount of oxygen-containing gas flowing through the oxygen (metering) valve 160 in the oxygen inlet line 155 to provide a target amount (volume%) of oxygen fed through the gas distribution plate 170 in the fluidized bed container 110.

[0089] Now for reference Figure 2 This illustrates a catalyst activation system 200 consistent with another aspect of this disclosure. Figure 2 Reference numbers in the text are usually related to the references to Figure 1 Components with similar numbering are described in the same way, with the following exceptions. Figure 2 In this process, an inert gas (e.g., nitrogen) is supplied from an inert gas source 230 through an inert inlet line 235 and through an inert gas valve 240 (when valve 240 is open), and subsequently through a gas distribution plate 270 in the fluidized bed container 210, wherein the gas flow direction 275 is upward through the fluidized bed container 210. Similarly, Figure 2 Oxygen-containing gas (e.g., air) is delivered from oxygen source 250 through oxygen inlet line 255 and through oxygen valve 260 (when valve 260 is open), and then through gas distribution plate 270 in fluidized bed container 210, wherein the gas flow direction 275 is upward through fluidized bed container 210.

[0090] Therefore, in a similar way Figure 1 In this way, Figure 2The controller 290 can circulate between introducing inert gas into the fluidized bed container 210 through the inert gas inlet line 235 by opening the inert gas valve 240 and closing the oxygen valve 260, and introducing oxygen-containing gas into the fluidized bed container 210 through the oxygen inlet line 255 by opening the oxygen valve 260 and closing the inert gas valve 240. Therefore, if information or data 285 from the thermocouple 220 indicates a rapid temperature rise in the fluidized bed container 210 (e.g., exothermic), the controller 290 can open the inert gas valve 240 and close the oxygen valve 260, thereby reducing the rate of temperature rise.

[0091] Polymerization process Olefin polymers (e.g., ethylene polymers) can be produced using activated chromium catalysts and any suitable olefin polymerization process, employing various types of polymerization reactors, polymerization reactor systems, and polymerization reaction conditions. One such olefin polymerization process may include (I) performing any process (e.g., a first or second process) to produce the activated chromium catalyst disclosed herein, and (II) contacting said activated chromium catalyst and optional co-catalyst with olefin monomers and optional olefin comonomers in a polymerization reactor system under polymerization conditions to produce the olefin polymer. The invention also covers any olefin polymer (e.g., ethylene polymer) produced by any polymerization process disclosed herein.

[0092] An activated chromium catalyst (and optionally a co-catalyst) produced by the first or second process can be contacted with olefin monomers and optionally olefin comonomers in a polymerization reactor system under polymerization conditions to produce an olefin polymer. Alternatively, a mixture of an activated chromium catalyst produced by the first or second process and another activated chromium catalyst (and optionally a co-catalyst) produced or activated by the first, second, or another process can be contacted with olefin monomers and optionally olefin comonomers in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

[0093] In polymerization processes, co-catalysts can be used in conjunction with activated chromium catalysts. In one aspect, the co-catalyst may comprise an aluminum oxane compound, an organoaluminum compound, or an organoboron compound, and this includes combinations of more than one co-catalyst compound. Representative and non-limiting examples of aluminum oxanes include methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, n-propylaluminoxane, isopropylaluminoxane, n-butylaluminoxane, tert-butylaluminoxane, sec-butylaluminoxane, isobutylaluminoxane, 1-pentylaluminoxane, 2-pentylaluminoxane, 3-pentylaluminoxane, isopentylaluminoxane, neopentylaluminoxane, etc., or any combination thereof. Representative and non-limiting examples of organoaluminum compounds include trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diisobutylaluminum hydrogenate, diethylaluminum ethanol, diethylaluminum chloride, etc., or any combination thereof. Representative and non-limiting examples of organoboron compounds include tri-n-butylborane, tripropylborane, triethylborane, and any combination thereof. The cocatalysts that can be used are not limited to those described above. Other suitable cocatalysts (such as organomagnesium and organolithium) are well known to those skilled in the art, including, for example, those disclosed in U.S. Patent Nos. 3,242,099, 4,794,096, 4,808,561, 5,576,259, 5,807,938, 5,919,983, 7,294,599, 7,601,665, 7,884,163, 8,114,946, and 8,309,485.

[0094] As used herein, a “polymerization reactor” includes any polymerization reactor capable of polymerizing olefin monomers and comonomers (one or more comonomers) to produce homopolymers, copolymers, terpolymers, etc. Various types of polymerization reactors include those that may be referred to as batch reactors, slurry reactors, gas-phase reactors, solution reactors, high-pressure reactors, tubular reactors, autoclave reactors, etc., or combinations thereof; or alternatively, polymerization reactor systems may include slurry reactors, gas-phase reactors, solution reactors, or combinations thereof. The polymerization conditions for various reactor types are well known to those skilled in the art. Gas-phase reactors may include fluidized bed reactors or staged horizontal reactors. Slurry reactors may include vertical and / or horizontal circulation. High-pressure reactors may include autoclaves and / or tubular reactors. Reactor types may include batch or continuous processes. Continuous processes may use batch and / or continuous product discharge. Polymerization reactor systems and processes may also include partial or complete direct recycling of unreacted monomers, unreacted comonomers, and / or diluents.

[0095] Polymerization reactor systems may include a single reactor or multiple reactors of the same or different types (two reactors, more than two reactors). For example, a polymerization reactor system may include a slurry reactor, a gas-phase reactor, a solution reactor, or a combination of two or more of these reactors. Polymer production in multiple reactors may include several stages in at least two separate polymerization reactors interconnected by transfer devices, making it possible to transfer polymer obtained from a first polymerization reactor to a second reactor. The polymerization conditions required in one of the reactors may differ from the operating conditions of the other reactors. Alternatively, polymerization in multiple reactors may include manually transferring polymer from one reactor to a subsequent reactor to continue polymerization. Multiple reactor systems may include any combination, including but not limited to multiple circulating reactors, multiple gas-phase reactors, a combination of circulating and gas-phase reactors, multiple high-pressure reactors, or a combination of high-pressure reactors with circulating and / or gas-phase reactors. Multiple reactors may operate in series, in parallel, or in a combination of series and parallel. Therefore, the present invention covers polymerization reactor systems including a single reactor, including two reactors, and including more than two reactors. In some aspects of the invention, a polymerization reactor system may include a slurry reactor, a gas-phase reactor, a solution reactor, and combinations of multiple reactors thereof.

[0096] According to one aspect, the polymerization reactor system may include at least one circulating slurry reactor comprising vertical or horizontal circulation. Monomers, diluents, catalysts, and comonomers may be continuously fed into the circulating reactor where polymerization occurs. Typically, a continuous process may include the continuous introduction of monomers / comonomers, catalysts, and diluents into the polymerization reactor, and the continuous removal of a suspension containing polymer particles and diluents from the reactor. The reactor effluent may be flashed to remove solid polymers from the liquid containing diluents, monomers, and / or comonomers. Various techniques may be used for this separation step, including but not limited to flashing, which may include any combination of heating and depressurization, separation by cyclone action in a cyclone separator or hydrocyclone, or separation by centrifugation.

[0097] Typical slurry polymerization processes (also known as particle-forming processes) are disclosed, for example, in U.S. Patent Nos. 3,248,179, 4,501,885, 5,565,175, 5,575,979, 6,239,235, 6,262,191, 6,833,415, and 8,822,608. Suitable diluents used in slurry polymerization include, but are not limited to, the monomers being polymerized and hydrocarbons that are liquid under the reaction conditions. Examples of suitable diluents include, but are not limited to, hydrocarbons such as propane, cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, and n-hexane. Some cyclic polymerization reactions can occur under bulk conditions without the use of diluents.

[0098] According to another aspect, the polymerization reactor system may include at least one gas-phase reactor (e.g., a fluidized bed reactor). Such reactor systems may employ a continuous recycle stream containing one or more monomers, which continuously circulates through a fluidized bed under polymerization conditions in the presence of a catalyst. The recycle stream can be discharged from the fluidized bed and recycled back into the reactor. Simultaneously, polymer products can be discharged from the reactor, and new or fresh monomers can be added to replace the monomers polymerized. Such gas-phase reactors may include processes for multi-step gas-phase polymerization of olefins, wherein olefins are polymerized in the gas phase in at least two separate gas-phase polymerization zones, while a catalyst-containing polymer formed in a first polymerization zone is fed into a second polymerization zone. Representative gas-phase reactors are disclosed in U.S. Patent Nos. 5,352,749, 4,588,790, 5,436,304, 7,531,606, and 7,598,327.

[0099] According to another approach, the polymerization reactor system may include a high-pressure polymerization reactor, such as a tubular reactor or an autoclave reactor. The tubular reactor may have several zones in which fresh monomers, initiators, or catalysts are added. The monomers may be entrained in an inert gas stream and introduced in one zone of the reactor. The initiator, catalyst, and / or catalyst components may be entrained in the gas stream and introduced in another zone of the reactor. The gas streams may be intermixed for polymerization. Heat and pressure may be appropriately used to obtain optimal polymerization reaction conditions.

[0100] According to another aspect, the polymerization reactor system may include a solution polymerization reactor, in which the monomer / comonomer is contacted with the catalyst by suitable stirring or other means. A support containing an inert organic diluent or excess monomer may be used. Where necessary, the monomer / comonomer may be contacted with the catalytic reaction products in the gas phase, with or without liquid material. The polymerization zone may be maintained at temperatures and pressures that allow a polymer solution to form in the reaction medium. Stirring may be used to obtain better temperature control and maintain a homogeneous polymerization mixture throughout the polymerization zone. Appropriate means are used to dissipate the exothermic reaction.

[0101] The polymerization reactor system may also include any combination of at least one feed system, at least one feed system for the catalyst or catalyst components, and / or at least one polymer recovery system. Suitable reactor systems may also include systems for feedstock purification, catalyst storage and preparation, extrusion, reactor cooling, polymer recovery, fractionation, recycling, storage, loading, laboratory analysis, and process control. Depending on the desired properties of the olefin polymer, hydrogen may be added to the polymerization reactor as needed (e.g., continuously or pulsedly).

[0102] Polymerization conditions that can be controlled to improve efficiency and provide desired polymer properties can include temperature, pressure, and the concentrations of various reactants. Polymerization temperature can affect catalyst yield, polymer molecular weight, and molecular weight distribution. For example, to produce a specific grade of olefin polymer (or ethylene polymer), various polymerization conditions can be kept substantially constant. According to the Gibbs free energy equation, a suitable polymerization temperature can be any temperature below the depolymerization temperature. Typically, depending on the type of polymerization reactor, this includes, for example, 60°C to 280°C or 60°C to 120°C. In some reactor systems, polymerization temperatures are generally in the range of about 70°C to 105°C or 75°C to 100°C.

[0103] The appropriate pressure will also vary depending on the reactor and type of polymerization. Liquid-phase polymerization in a circulating reactor typically occurs at pressures less than 1000 psig (6.9 MPa). Gas-phase polymerization typically occurs at pressures of approximately 200 to 500 psig (1.4 MPa to 3.4 MPa). High-pressure polymerization in tubular or autoclave reactors typically takes place at 20,000 to 75,000 psig (138 MPa to 517 MPa). Polymerization reactors can also be operated in the supercritical region, generally at higher temperatures and pressures. Operation above the critical point (supercritical phase) of the pressure / temperature diagram can provide advantages for the polymerization process.

[0104] Olefin monomers that can be used with the activated chromium catalyst and polymerization process of the present invention typically include olefin compounds having 2 to 30 carbon atoms per molecule and having at least one olefinic double bond, such as ethylene or propylene. In one aspect, the olefin monomer may contain C2-C 20 Olefins; alternatively, C2-C 20 α-olefins; alternatively, C2-C 10 Olefins; alternatively, C2-C 10 α-olefin; alternatively, the olefin monomer may contain ethylene; or alternatively, the olefin monomer may contain propylene (e.g., to produce a polypropylene homopolymer or a propylene-based copolymer).

[0105] When copolymers (or alternatively, terpolymers) are required, the olefin monomers and olefin comonomers may independently include, for example, C2-C. 20 α-olefins. In some aspects, the olefin monomer may include ethylene or propylene, which, together with at least one comonomer (e.g., C2-C...), may be used to form an α-olefin monomer. 20 α-olefins or C3-C 20 (α-olefin) copolymerization. According to one aspect of the invention, the olefin monomer used in the polymerization process may include ethylene. In this aspect, the comonomer may contain C3-C...10 α-olefin; alternatively, the comonomer may comprise 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, styrene or any combination thereof; alternatively, the comonomer may comprise 1-butene, 1-hexene, 1-octene or any combination thereof; alternatively, the comonomer may comprise 1-butene; alternatively, the comonomer may comprise 1-hexene; or alternatively, the comonomer may comprise 1-octene.

[0106] In one aspect, the polymerization process can be carried out in a commercial circulating reactor at a productivity of 2000 to 5000 g of polymer per gram of catalyst and / or a space-time yield greater than or equal to 2, 2.5, 2.8, 3, or 4 (lb / hr) / gal and / or less than or equal to 6, 5.5, or 5 (lb / hr) / gal, to produce an ethylene / 1-hexene copolymer with a density of at least 0.947 g / cc as determined by ISO 1183 Part 2. The space-time yield can be in the range of any minimum to any maximum value listed above, and therefore representative and non-limiting ranges of space-time yield include 2 to 6, 2 to 5, 2.5 to 5.5, 2.8 to 6, 3 to 6, 3 to 5.5, 4 to 6, or 4 to 5 (lb / hr) / gal.

[0107] In another aspect, the polymerization process can be carried out in a commercial circulating reactor at a productivity of 2000 to 5000 g of polymer per gram of catalyst and / or a space-time yield greater than or equal to 2, 2.5, 2.8, 3, or 4 (lb / hr) / gal and / or less than or equal to 6, 5.5, or 5 (lb / hr) / gal, to produce ethylene / 1-hexene copolymers with a density of at least 0.938 g / cc as determined by ISO 1183 Part 2. As mentioned above, the space-time yield can be in the range of any minimum to any maximum value listed above, and therefore representative and non-limiting ranges of space-time yields include 2 to 6, 2 to 5, 2.5 to 5.5, 2.8 to 6, 3 to 6, 3 to 5.5, 4 to 6, or 4 to 5 (lb / hr) / gal.

[0108] Ethylene polymers and olefin polymers This invention also relates to and includes olefin polymers produced using any of the chromium catalysts and polymerization processes disclosed herein. The olefin polymers covered herein may include any polymer produced from any olefin monomers and optional comonomers described herein. For example, olefin polymers may include ethylene homopolymers, ethylene copolymers (e.g., ethylene / α-olefins, ethylene / 1-butene, ethylene / 1-hexene, ethylene / 1-octene, etc.), propylene homopolymers, propylene copolymers, ethylene terpolymers, propylene terpolymers, etc., including any combination thereof. In one aspect, olefin polymers may include ethylene homopolymers, ethylene / 1-butene copolymers, ethylene / 1-hexene copolymers, and / or ethylene / 1-octene copolymers, while in another aspect, olefin polymers may include ethylene / 1-hexene copolymers.

[0109] If the resulting polymer produced according to the invention is, for example, an ethylene polymer, its properties can be characterized by various analytical techniques known and used in the polyolefin industry. Articles may be formed from the olefin polymers (e.g., ethylene polymers) of the invention, and / or may contain the olefin polymers (e.g., ethylene polymers) of the invention, the typical properties of which are provided below.

[0110] Illustrative and non-limiting examples of first ethylene polymers (e.g., ethylene / α-olefin copolymers) produced using the activated chromium catalyst disclosed herein can have high loading melt index (HLMI) in the range of 10 to 80 g / 10 min and in the range of 0.93 to 0.96 g / cm³. 3 Density within the range and per ft 2 A 25-micrometer thick film contains less than or equal to 100 gels (or per ft) 2 The total gel count for a 25-micron thick membrane is defined as 80 or less, 60 or less, 40 or less, 30 or less, 20 or less, 10 or less, or 5 or less gels, where the membrane gels include those larger than 200 µm. Alternatively, a gel count >200 µm caused by undisturbed catalyst particles (e.g., undisturbed Cr / silica catalyst particles) can be defined as per ft. 2 A 25-micrometer thick film contains less than or equal to 100 gels, or per ft 2 The 25-micrometer-thick film contains 80 or less, 60 or less, 40 or less, 30 or less, 20 or less, 10 or less, or 5 or less gels. The ethylene polymer contains a total of 150 to 680 ppm silica, 1.5 to 6.8 ppm chromium, and 1.5 to 40 ppm titanium (if present) in both decomposed and unfragmented forms.

[0111] Illustrative and non-limiting examples of second ethylene polymers (e.g., ethylene / α-olefin copolymers) may have melt index (MI) in the range of 0.1 g / 10 min to 1 g / 10 min, and in the range of 0.93 to 0.96 g / cm³. 3 Density within the range and per ft 2 A 25-micrometer thick film contains less than or equal to 100 gels (or per ft) 2 The total membrane gel count is defined as 80 or less, 60 or less, 40 or less, 30 or less, 20 or less, 10 or less, or 5 or less gels in a 25-micron thick membrane, where membrane gels include those larger than 200 µm (and for catalyst particle gel counts, this can be caused by undisturbed catalyst particles). The ethylene polymer contains 150 to 680 ppm silica, 1.5 to 6.8 ppm chromium, and 1.5 to 40 ppm titanium (if present).

[0112] Furthermore, unless otherwise stated, these illustrative first and second ethylene polymers (which are generally in granule or bead form) according to the invention may also have any and any combination of the polymer properties listed below.

[0113] The density of ethylene-based polymers typically ranges from 0.93 to 0.96 or 0.93 to 0.956 g / cm³. 3 Within a certain range. In one respect, the density may be 0.934 to 0.96, in another respect 0.934 to 0.956, in yet another respect 0.934 to 0.95, or in yet another respect 0.945 to 0.958 g / cm³. 3 Within the range.

[0114] Ethylene polymers can exhibit a variety of melt flow characteristics, such as those indicated by a high load melt index (HLMI) in the range of 10 to 80 g / 10 min. In some respects, the HLMI of ethylene polymers can fall within the ranges of 10 to 70, 10 to 60, 10 to 50, 20 to 80, 20 to 50, or 30 to 50 g / 10 min. Alternatively or alternatively, these ethylene polymers can have melt indexes (MI) of 0.1 to 1 g / 10 min, and more typically 0.1 to 0.75, 0.1 to 0.6, 0.2 to 1, 0.2 to 0.6, or 0.3 to 0.6 g / 10 min.

[0115] On one hand, the ethylene polymer may have Mw in the range of 100,000 to 250,000 g / mol, 120,000 to 200,000 g / mol, or 140,000 to 180,000 g / mol. For example, Mw may be less than or equal to 180,000 g / mol, less than or equal to 170,000 g / mol, or less than or equal to 160,000 g / mol. Alternatively or additionally, the ethylene polymer may have Mn in the range of 3,000 to 25,000 g / mol, 8,000 to 20,000 g / mol, 10,000 to 18,000 g / mol, or 12,000 to 15,000 g / mol. For example, Mn may be less than or equal to 15,000 g / mol, less than or equal to 14,000 g / mol, or less than or equal to 13,000 g / mol. Alternatively or concurrently, the ethylene polymer may have an Mz of 500,000 to 2,000,000 g / mol, 500,000 to 1,800,000 g / mol, or 600,000 to 1,500,000 g / mol. For example, Mz may be less than or equal to 1,300,000 g / mol, less than or equal to 1,100,000 g / mol, or less than or equal to 1,000,000 g / mol. Not limited thereto, these ethylene polymers may have an Mw / Mn ratio in the range of 7 to 20, such as 8 to 18, 9 to 17, 9 to 15, or 10 to 14. For example, Mw / Mn may be less than or equal to 14, less than or equal to 13, less than or equal to 12.5, or less than or equal to 11.5. Similarly, representative ranges for Mz / Mw ratios include 5 to 10, 5 to 9, 6 to 10, or 6 to 9. For example, Mz / Mw can be less than or equal to 8, less than or equal to 7.5, less than or equal to 7, less than or equal to 6.5, or less than or equal to 6.

[0116] Alternatively, these ethylene polymers may have a CY-a parameter of 0.1 to 0.3 in one aspect, 0.14 to 0.3 in another, 0.15 to 0.28 in yet another, 0.16 to 0.26 in yet another, 0.17 to 0.24 in yet another, and 0.18 to 0.22 in yet another. For example, the CY-a parameter may be less than or equal to 0.18, less than or equal to 0.17, less than or equal to 0.165, less than or equal to 0.16, less than or equal to 0.155, or less than or equal to 0.15. This rheological parameter is determined from viscosity data measured at 190 °C using the Carreau-Yasuda (CY) empirical model described herein.

[0117] Furthermore, as discussed herein, the ethylene polymer is produced in the presence of a supported active chromium catalyst. Ziegler-Natta catalyst systems and metallocene-based catalyst systems are not required. Therefore, the ethylene polymer may be free of measurable amounts of zirconium, hafnium, titanium, vanadium, or magnesium (catalyst residues), i.e., less than 0.1 ppm by weight. In some respects, the ethylene polymer may independently contain less than 0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm of zirconium (or hafnium, or titanium, or vanadium, or magnesium). The amounts of these elements can be determined by ICP analysis on a PerkinElmer Optima 8300 instrument. The polymer sample can be ashed overnight in a Thermolyne furnace with sulfuric acid, followed by acid digestion in a HotBlock with HCl and HNO3 (3:1 v:v).

[0118] In practice, ethylene polymers typically contain 1.5 to 6.8 ppm of chromium, 1.5 to 40 ppm of titanium (when present), and 150 to 680 ppm of silica (by weight). Other illustrative ranges for chromium content in these ethylene polymers include, but are not limited to, 1.8 to 6 ppm, 2 to 6.8 ppm, 2 to 6 ppm, 2 to 5 ppm, 1.5 to 6 ppm, 1.5 to 5.5 ppm, 1.5 to 5 ppm, or 3 to 6 ppm of chromium. Other illustrative ranges for titanium content in these ethylene polymers include, but are not limited to, 1.5 to 30 ppm, 2 to 40 ppm, 2 to 30 ppm, 2 to 10 ppm, 3 to 30 ppm, 3 to 20 ppm, 3 to 10 ppm, 4 to 20 ppm, 5 to 40 ppm, 5 to 20 ppm, or 5 to 15 ppm of titanium (when present). Other illustrative ranges for the silica content of these ethylene polymers include, but are not limited to, 180 to 600 ppm, 200 to 680 ppm, 200 to 600 ppm, 200 to 500 ppm, 150 to 600 ppm, 150 to 550 ppm, or 150 to 500 ppm silica. The silica content of the polymer is determined by ash content testing.

[0119] The amount of gel count can be based on the total membrane gel count (all membrane defects with a diameter greater than 200 micrometers) or the catalyst particle gel count (membrane defects with a diameter greater than 200 micrometers caused by catalyst particles), i.e., per ft 2The gel count of a 25-micron-thick ethylene polymer film. Most gels in chromium-derived polymers are catalyst particle gels (hard gels) caused by supported catalyst particles. When using these supported chromium catalysts for ethylene polymerization, most catalyst particles break down or decompose into barely perceptible small fragments that disperse in the final polymer without causing problems, especially in film products. However, depending on the polymerization conditions, some catalyst particles may be discharged from the reactor before becoming active and thus decomposing due to polymerization. These unbroken catalyst particles can cause visual defects on the surface of the final product or article, commonly referred to as “gels”, “hard gels”, or “catalyst gels,” and film grades are particularly sensitive to this problem (notably, such catalyst particle gels can also produce noticeable defects on the surface of thick parts, resulting in poor surface aesthetics of the final product or article, and this surface roughness can also interfere with printing operations). Therefore, polymer film grades typically have strict manufacturing specifications for gels larger than 200 microns in diameter. During polymer manufacturing, the polymer is formed into a 25-micron-thick film, and the gel count is automatically measured by an in-line camera specifically designed to count gels larger than 200 microns. The total gel count includes catalyst particle gel as well as gel formed due to contamination such as foreign matter, polymer particles, or additive particles.

[0120] Typically, to be considered a "gel," optical defects identified by the camera and computer on a gel analyzer must be recorded as gel sizes greater than 200 µm in diameter. Empirically, catalyst particles with diameters of 100+ µm are often recorded as 200+ µm gels because polymers sometimes adhere to the catalyst particles, thereby increasing their size, and also due to the "lens effect," where the catalyst particles appear larger due to the lenticular polymer coating. The latter is an optical magnification of the catalyst particle size because a convex lens made of transparent polymer forms around the catalyst particle. Therefore, catalyst particle gelation can be reduced by minimizing catalyst particles with a size of 100 μm or larger in the ethylene polymer.

[0121] Another unexpected benefit of using the supported chromium catalyst activated as described herein is the improved processability of the ethylene polymers compared to polymers produced using chromium catalysts activated in a conventional manner (control or comparative examples, discussed further below). In extrusion processing for blown films, pipes, blow molding, and other conversion applications, the extrusion pressure can be reduced by at least 3%, at least 5%, at least 8%, or at least 10%, or at least 15%, and in some cases by up to 20% or more. This improved processability can be measured or quantified on a granulating extruder that forms the ethylene polymer into granules or beads, or on an extruder used for film production. Therefore, this also applies to granulation performed during the manufacture of the polymers of this invention. Again, the extrusion pressure can be reduced by at least 3%, 5%, 8%, 10%, or 15%, or up to 20% or more.

[0122] Similarly, for the polymers of the present invention, the melt temperature is typically low during extrusion, molding, granulation, and other processes. The extrusion melt temperature can typically be reduced by at least 5℉, 8℉, 10℉, 15℉, or 20℉, or up to 25℉ (3℃, 4℃, 6℃, 8℃, or 11℃, or up to 14℃) or more. Furthermore, compared to polymers made with a control catalyst, the power consumption, measured by the extruder's ampere number, is also reduced during the corresponding extrusion process. Power consumption can typically be reduced by at least 5%, or at least 8%, or 10%, or 12%, or 15%. Additionally, the specific energy or work imparted to the polymer can be reduced by at least 1%, or 2%, or 3%, or 4%.

[0123] Another advantage of polymers prepared using the catalyst of this invention is that they typically exhibit enhanced mixing during extrusion. Evidence of this is the significant decrease in melt index as the material passes through the extruder, indicating increased chain entanglement. Melt index changes can be 0.21, 0.22, 0.23, 0.24, 0.25, or 0.26 g / 10 min. When expressed as a percentage, this can be a melt index decrease of at least 30%, 40%, 42%, 45%, or 48%, and a melt index decrease of up to 50%, 55%, or 60%, or more. HLMI may also decrease by a similar percentage.

[0124] Products and products Articles may be formed from the olefin polymers (e.g., ethylene polymers) of the present invention, and / or may contain the olefin polymers (e.g., ethylene polymers) of the present invention, and are therefore covered herein. For example, articles that may contain the polymers of the present invention may include, but are not limited to, agricultural films, geomembranes, packaging films, pallet wrapping films, automotive parts, bottles, chemical containers, barrels, fibers or fabrics, food packaging films or containers, food contact articles, fuel tanks, geomembranes, household containers, liners, molded products, medical devices or materials, outdoor storage products, outdoor recreational equipment, pipes, sheets or tapes, toys or traffic barriers, etc. Various processes can be used to form these articles. Non-limiting examples of these processes include injection molding, blow molding, rotational molding, film extrusion, sheet extrusion, profile extrusion, thermoforming, etc. Furthermore, additives and modifiers are typically added to these polymers to provide beneficial polymer processing or end-use product properties. Such processes and materials are described in Modern Plastics Encyclopedia Mid-November 1995, Volume 72, Issue 12; and Film Extrusion Manual – Process, Materials, Properties , TAPPI Publishing, 1992. In some aspects of the invention, the article may comprise any of the olefin polymers (or ethylene polymers) described herein, and the article may be or may comprise a film (e.g., a blown film), a tube, or a blow-molded product.

[0125] Example The following embodiments further illustrate the present invention, and these embodiments should not be construed as limiting the scope of the invention in any way. After reading this description, those skilled in the art will realize various other aspects, modifications, and equivalents without departing from the spirit of the invention or the scope of the appended claims.

[0126] The following laboratory tests were conducted to compare the activation of the precatalyst with that of the standard catalyst. Approximately 10 g of the precatalyst sample was placed in a 1.75-inch quartz tube with a sintered quartz disk at the bottom. While the precatalyst was loaded onto the disk, dry air was introduced at a pressure of 1.6–1.8 standard ft. 3 The catalyst was blown through the pan at a linear rate of 45-51 L / hr. Then, the electric furnace around the quartz tube was turned on, and the temperature was increased to the target temperature at a rate of 400°C / hr, typically reaching 650°C. At this temperature, the catalyst was fluidized in dry air for 3 hours. Subsequently, the catalyst was collected and stored under dry nitrogen, under which it was protected from oxygen and moisture until ready for polymerization testing. The comparative precatalyst was a commercially available chromium titanate / silica precatalyst containing 1 wt.% chromium and 2.5 wt.% titanium and having a 500 m... 2 / g BET surface area, 2.5mL / g pore volume and 130μm average (d50) particle size.

[0127] Other catalyst activations (activation methods 1-5) were carried out in a large-scale fluidized bed calciner with a diameter of 42 inches, where the gas flow rate was 0.1 ft / sec below 700°C and 0.2 ft / sec above that temperature. The calciner was designed similarly to the quartz laboratory activator, only constructed on a larger scale. The temperatures (within the calciner) were the average of three (3) thermocouples located at the top, bottom, and middle of the fluidized bed calciner. The catalyst / pre-catalyst temperature was effectively the same as the calciner temperature. Figure 3 This is an indication of the time-temperature activation sequence and the gas feed used in activation methods 1-5 – nitrogen or oxygen (air), except for the exothermic elimination portion that occurs during the first few hours, which will be discussed in detail below.

[0128] The precatalysts used in activation methods 1-5 were prepared from 550 lb of silica (dry basis), wherein the silica has a 450 μm... 2 The BET surface area was 1.9 mL / g and the pore volume was 1.9 mL / g. The average d50 particle size was 60 μm. Silica was charged into a 1000-gal reactor and mixed with 2750 lb of deionized water. The slurry was stirred and the other components outlined in Table 1 below were added. After adding all components, the mixture was spray-dried to form a pre-catalyst.

[0129] Table 1

[0130] Activation Method 1: At a temperature of 600℉ (315°C), approximately 625 lb of pre-catalyst was loaded into the calcining furnace in four unequal portions under nitrogen atmosphere. The first portion was slightly smaller than the subsequent portions. As the portions were loaded, the temperature rapidly decreased, reaching 350℉ (177°C) upon completion of loading. The nitrogen flow was then switched to dry air, and external heat was applied to slowly raise the temperature. At approximately 450℉ (232°C), the organic matter on the catalyst began to oxidize, releasing heat—the exothermic process began. The temperature then rapidly increased to 800℉ (427°C). To stop the exothermic process and prevent overheating and damage to the catalyst and calcining furnace, the gas was switched back to nitrogen when the temperature reached 700℉ (371°C). However, the temperature continued to rise for another 100℉ (56°C), while the last air in the container was vented and replaced with nitrogen. This is shown in... Figure 4 The figure shows the temperature over time for the exothermic portion of the entire activation process. Note that the gas flow is either nitrogen or oxygen (air), and is represented by different symbols.

[0131] The temperature was slowly lowered back to 700℉ (371℃), and then the nitrogen was replaced with air again. In this second cycle, heat release began rapidly again, and the temperature quickly rose to nearly 900℉ (482℃). Again, the gas reverted to nitrogen at approximately 775℉ (413℃), but the temperature continued to rise to nearly 900℉ (482℃). The temperature was then slowly cooled back to 700℉ (371℃) under nitrogen, at which point air was replaced with nitrogen again. However, this time no further heat release was observed. Activation then continued normally in air, as... Figure 3 As shown, the final holding temperature after heating to 1350℉ (732℃) is...

[0132] Activation Method 2: Follows the general procedure of Activation Method 1. Again, two exothermic cycles were used, producing similar temperature / time curves, as shown in... Figure 5 In the middle. For example Figure 3 As shown, after the heat release is completed, it is further activated in air to 1350℉ (732℃).

[0133] Activation methods 3-4: In these methods, exothermic reactions are controlled using much shorter cycles. In activation methods 3-4, air is added in 2-minute pulses, followed by 5-minute nitrogen pulses. This has a significant effect in smoothing out the temperature rise associated with exothermic reactions. Figures 6A-6B and Figures 7A-7B The temperature / time curve for the exothermic portion of the entire activation process is shown. Note the characteristic of a smooth temperature rise, marked by a series of small increases and decreases, resembling almost a sine wave or a step. Figure 3 As shown, after the heat release is completed, it is further activated in air to 1350℉ (732℃).

[0134] Activation Method 5: In Activation Method 5, an automated system is used to control the pulses of nitrogen and air, as well as to open and close the appropriate valves required to complete the process. Air is added in 40-second pulses, followed by 5-minute nitrogen pulses. Throughout this activation method, and in other activation methods, the total fluidizing gas rate is maintained at the normal rate. The automatically generated smaller pulses further smooth the flow. Figures 8A-8B The ramp rate in activation method 5 is shown. Using this technique, the activation process can be operated unattended without any risk of damage to the activation vessel or chromium catalyst from runaway exothermic temperatures.

[0135] Table 2 summarizes activation methods 1-5. The weight of the pre-catalyst charged, and the weight and percentage of catalyst recovered after activation, are shown. The difference between the charge weight and the recovered weight is due to the combustion of volatile organic compounds, which results in exothermic reactions. The initial (ignition) temperature and final (maximum) temperature of the exothermic portion activated under nitrogen are also shown, along with the average ramp rate calculated again over the exothermic time period.

[0136] Ethylene was then polymerized using catalysts from activation methods 1-5. Table 3 shows the catalyst charge weight, amount of polymer produced, total time, and induction time for each polymerization experiment, from which the activity was calculated. MI, I10, and high-load melt index (HLMI) are also shown in Table 3. For reference, the aforementioned comparative catalysts were also tested several times simultaneously and are shown in Table 3. It is particularly noteworthy that the performance of the catalysts of the present invention from activation methods 1-5 is comparable to that of the comparative catalysts, exhibiting similar activity and superior polymer properties (e.g., higher HLMI).

[0137] The amount of Cr(VI) was determined by mixing 2 g of catalyst with 20 mL of 2 M H₂SO₄ solution and then adding 5 drops of 1,000-phenanthroline ferrous ion Fe(+3) indicator. This typically turns the mixture blue-green, indicating the presence of Fe(III) ions. The mixture was then titrated to the 1,000-phenanthroline ferrous ion endpoint (red) using ferrous ammonium sulfate solution, which had previously been calibrated by reacting with a standardized 0.1 M sodium dichromate solution. The endpoint was reached when the mixture turned red, the titrant volume was recorded, and the oxidizing power of the catalyst was calculated and expressed as wt.% Cr(VI).

[0138] Both laboratory-activated and large-scale activated catalysts were tested in polymerization experiments using a 2.2-L steel reactor equipped with a marine agitator rotating at 500 rpm. The reactor was surrounded by a steel jacket through which a mixture of steam and water was passed, regulated by electronic control instruments to maintain a constant temperature of 105°C (+ / - 0.5°C). Unless otherwise stated, a small amount (typically 0.01 to 0.10 g) of solid catalyst was first added to the dry reactor under nitrogen atmosphere. Next, 1.2 L of liquid isobutane was added and the reactor was heated to the specified temperature (105°C). Finally, ethylene was added to the reactor to reach a fixed pressure of 550 psig, which was maintained during the experiment. Stirring continued until approximately 3000 g of polymer was produced per gram of catalyst, and the instantaneous reaction rate was recorded by recording the ethylene flow rate entering the reactor to maintain the set pressure.

[0139] Once the desired productivity of 3000 g / g is reached, the ethylene flow is stopped, and the reactor is slowly depressurized and opened to recover the granular polymer powder. In all cases, the reactor is clean, showing no signs of scale, coatings, or other forms of fouling. The polymer powder is then removed and weighed. Activity is specified as the number of grams of polymer produced per gram of solid catalyst charged per hour.

[0140] Then, the melt index and high-load melt index of the recycled polymer were obtained. The melt index (MI, I2, g / 10 min) was determined at 190°C with a weight of 2.16 kg according to ASTM D1238-E, condition 190 / 2, and the I10 (g / 10 min) was determined at 190°C with a weight of 10 kg according to ASTM D1238. The high-load melt index (HLMI, I2, g / 10 min) was determined at 190°C with a weight of 21.6 kg according to ASTM D1238-E, condition 190 / 21.6. 21 According to ASTM D1505 and ASTM D4703, on compression-molded samples cooled at 15°C per minute and conditioned at room temperature for 40 hours, the concentration is expressed in grams per cubic centimeter (g / cm³). 3 Density is measured in units of 1 / 2.

[0141] Table 2

[0142] Table 3

[0143] The catalyst activated by methods 3-5 of the present invention was then used in a large-scale 18,000-gallon circulating reactor with isobutane as a diluent to prepare a series of polymers with a density of about 0.938 g / cc and a melt index of about 0.2 g / 10 min. Table 4 below shows the reaction conditions. The comparative catalyst is the one described above, and the catalyst of the present invention is a mixture of catalysts produced in activation methods 3-5. Catalyst productivity and catalyst residue (ash) are summarized in Table 5, and surprisingly, the catalyst of the present invention exhibits significantly higher catalytic activity.

[0144] Table 4

[0145] Table 5

[0146] In summary, activation methods 3-5 offer three advantages: (i) controlled cycling or pulsation of nitrogen and air / oxygen stops the runaway temperature that occurs during the exothermic process, which would damage the activation vessel and catalyst, making it difficult to oxidize chromium to Cr(VI); (ii) controlled cycling or pulsation significantly reduces or eliminates organic emissions from oxidation, where a noticeable odor is present in methods 1-2 but surprisingly absent in methods 3-5; and (iii) controlled cycling or pulsation improves catalytic activity.

[0147] The invention has been described above with reference to numerous aspects and specific embodiments. Based on the detailed description above, many variations will occur to those skilled in the art. All such obvious variations are within the full scope of the appended claims. Other aspects of the invention may include, but are not limited to, the following (aspects are described as “comprising,” but alternatively, may be “substantially composed of” or “consisting of”): Aspect 1. An activation system comprising (a) a fluidized bed container having one or more heating zones and configured to fluidize and activate a supported chromium precatalyst; (b) one or more fluidizing gas inlets configured to introduce fluidizing gas into the fluidized bed container, the fluidizing gas comprising (i) an inert gas, (ii) an oxygen-containing gas, or (iii) a mixture of the inert gas and the oxygen-containing gas; (c) one or more thermocouples positioned inside the fluidized bed container for measuring an activation temperature inside the fluidized bed container; and (d) a controller configured to circulate or regulate (iii) the mixture of the inert gas and the oxygen-containing gas between (i) the inert gas and (ii) the oxygen-containing gas based on time intervals and / or based on the activation temperature measured by the one or more thermocouples.

[0148] Aspect 2. The system as defined in Aspect 1, wherein the inert gas comprises (or consists substantially of, or consists of) nitrogen, argon, or a combination thereof.

[0149] Aspect 3. The process as defined in Aspect 1 or 2, wherein the oxygen-containing gas comprises (or is substantially composed of, or is composed of) oxygen, air, a mixture of oxygen and an inert gas (e.g., nitrogen), a mixture of air and an inert gas (e.g., nitrogen), or a combination thereof, having any suitable oxygen volume percentage, such as 1 to 40 volume%, 1 to 30 volume%, 2 to 21 volume%, 3 to 25 volume%, or 4 to 10 volume%.

[0150] Aspect 4. The system as defined in any one of Aspects 1-3, wherein the fluidized bed vessel has two or more heating zones.

[0151] Aspect 5. A system as defined in any one of Aspects 1-4, wherein the system comprises two or more thermocouples.

[0152] Aspect 6. A system as defined in any one of Aspects 1-5, wherein the one or more fluidizing gas inlets comprise an inert gas inlet line and an oxygen-containing gas inlet line, and the controller is further configured to circulate between (1) introducing the inert gas into the fluidized bed container through the inert gas inlet line by opening a first valve on the inert gas inlet line and closing a second valve on the oxygen-containing gas inlet line and (2) introducing the oxygen-containing gas into the fluidized bed container through the oxygen-containing gas inlet line by opening the second valve and closing the first valve.

[0153] Aspect 7. The system as defined in any one of Aspects 1-5, wherein the one or more fluidizing gas inlets include a fluidizing gas inlet, and the controller is further configured to circulate between (1) introducing the inert gas into the fluidizing gas inlet through the inert gas inlet line by opening a first valve on the inert gas inlet line and closing a second valve on the oxygen-containing gas inlet line and (2) introducing the oxygen-containing gas into the fluidizing gas inlet through the oxygen-containing gas inlet line by opening the second valve and closing the first valve.

[0154] Aspect 8. The system as defined in any one of Aspects 1-7, wherein the controller is further configured to adjust the duration of feeding the inert gas independently in the range of 10 seconds to 15 minutes and the duration of feeding the oxygen-containing gas independently in the range of 10 seconds to 15 minutes.

[0155] Aspect 9. The system as defined in any one of Aspects 1-8, wherein the controller is further configured to adjust the average duration of feeding the inert gas, the average duration being greater than the average duration of feeding the oxygen-containing gas.

[0156] Aspect 10. The system as defined in any one of Aspects 1-9, wherein the controller is further configured to regulate the circulation of the inert gas and the oxygen-containing gas to maintain an average increase in activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min) within a temperature range from a lower temperature range of 250℉ to 700℉ (121℃ to 371℃ / min) to a higher temperature range of 700℉ to 950℉ (371℃ to 510℃ / min).

[0157] Aspect 11. The system as defined in aspect 10, wherein the average increase in the activation temperature is 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0158] Aspect 12. A system as defined in any of Aspects 1-11, wherein the controller is further configured to adjust any suitable number of cycles for introducing the inert gas and subsequently the oxygen-containing gas, or any number of cycles disclosed herein, such as 5 to 50, 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25, or 10 to 20.

[0159] Aspect 13. The system as defined in any one of Aspects 1-5, wherein the one or more fluidizing gas inlets include a fluidizing gas inlet, and the controller is further configured to regulate the mixture of the inert gas and the oxygen-containing gas in the fluidizing gas inlet by controlling a first flow rate of the inert gas entering the fluidizing gas inlet through an inert gas inlet line and a second flow rate of the oxygen-containing gas entering the fluidizing gas inlet through an oxygen-containing gas inlet line.

[0160] Aspect 14. The system as defined in any of Aspects 1-5 or 13, wherein the controller is further configured to control the relative amounts of the inert gas and the oxygen-containing gas in the mixture at any suitable oxygen volume%, for example, 1 to 10 volume%, 1 to 8 volume%, 2 to 8 volume%, 2 to 7 volume%, or 3 to 6 volume%.

[0161] Aspect 15. The system as defined in any one of Aspects 1-5 or 13-14, wherein the controller is further configured to regulate the mixture of the inert gas and the oxygen-containing gas to maintain an average increase in activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min) within a temperature range from a lower temperature in the range of 250℉ to 700℉ (121℃ to 371℃ / min) to a higher temperature in the range of 700℉ to 950℉ (371℃ to 510℃ / min).

[0162] Aspect 16. The system as defined in aspect 15, wherein the average increase in the activation temperature is 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0163] Aspect 17. A system as defined in any of Aspects 1-16, wherein the one or more fluidizing gas inlets are configured to introduce the fluidizing gas into the fluidized bed container at any suitable linear velocity or any linear velocity disclosed herein, such linear velocities as 0.05 to 0.6 ft / sec, 0.05 to 0.3 ft / sec, 0.1 to 0.4 ft / sec, 0.2 to 0.5 ft / sec, 0.2 to 0.4 ft / sec, or 0.2 to 0.3 ft / sec.

[0164] Aspect 18. The system as defined in any one of Aspects 1-17, wherein the controller is further configured to determine an exothermic increase in the activation temperature measured by the one or more thermocouples, for example, an increase of at least 30℉ (17°C) over 5 minutes.

[0165] Aspect 19. A system as defined in any one of Aspects 1-18, wherein the controller is further configured to determine an exothermic increase in the activation temperature as measured by the one or more thermocouples, for example, the second derivative of the temperature with respect to time is positive (acceleration of temperature with respect to time).

[0166] Aspect 20. A system as defined in any of Aspects 1-19, wherein the system is configured to operate in batches or, alternatively, continuously.

[0167] Aspect 21. A system as defined in any one of Aspects 1-20, wherein the supported chromium precatalyst has any suitable total pore volume or any range of total pore volume disclosed herein (e.g., 0.5 to 5 mL / g), any suitable BET surface area or any range of BET surface area disclosed herein (e.g., 100 to 700 m² / g). 2 / g) and any suitable average (d50) particle size or any range of average (d50) particle size disclosed herein (e.g., 10 to 500 micrometers).

[0168] Aspect 22. The system as defined in any of Aspects 1-21, wherein the supported chromium precatalyst contains any suitable amount of chromium or any amount within the range disclosed herein, for example, 0.1 to 5 wt.% chromium based on the weight of the precatalyst.

[0169] Aspect 23. The system as defined in any of Aspects 1-22, wherein the supported chromium precatalyst contains any suitable amount of titanium or any amount within the range disclosed herein, for example, 0.1 to 10 wt.% titanium based on the weight of the precatalyst.

[0170] Aspect 24. A process (for producing activated (calcined) chromium catalyst, said process) comprising (1) exposing a pre-catalyst in a fluidized bed vessel to a feed cycle of a second oxidizing gas and a second inert gas at a temperature T2 ranging from 250℉ to 700℉ (121°C to 371°C) to a temperature T3 ranging from 700℉ to 950℉ (371°C to 510°C), wherein the duration of each second oxidizing gas feed cycle is independently from 10 seconds to 15 minutes (e.g., 20-30 seconds), the duration of each second inert gas feed cycle is independently from 10 seconds to 15 minutes (e.g., 4-5 minutes), the average duration of the second oxidizing gas feed cycle is less than the average duration of the second inert gas feed cycle, and the average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3°C to 6°C / min). (e.g., 2℉-4℉ / min); and (2) while introducing a third inert gas or a third oxidizing gas into the fluidized bed vessel, heating the precatalyst to a temperature T4 in the range of 1000℉ to 1600℉ (538℃ to 871℃), and holding the precatalyst in the third inert gas or the third oxidizing gas at T4 for a holding time t1 in the range of 1 hour to 15 hours.

[0171] Aspect 25. The process as defined in aspect 24, wherein the second inert gas in each cycle of step (1) is the same or different and independently comprises (or substantially consists of, or consists of) nitrogen, argon or a combination thereof.

[0172] Aspect 26. The process as defined in Aspect 24 or 25, wherein the second oxidizing gas in each cycle of step (1) is the same or different and independently comprises (or consists of substantially the following, or consists of the following): oxygen, air, a mixture of oxygen and an inert gas (e.g., nitrogen), a mixture of air and an inert gas (e.g., nitrogen), or a combination thereof, having any suitable oxygen volume percentage, for example 1 to 40 volume%, 1 to 30 volume%, 2 to 21 volume%, 3 to 25 volume%, or 4 to 10 volume%.

[0173] Aspect 27. A process as defined in any of Aspects 24-26, wherein step (1) comprises any suitable number of cycles or any number of cycles disclosed herein, such as 5 to 50, 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25 or 10 to 20.

[0174] Aspect 28. A process as defined in any of Aspects 24-27, wherein any suitable average heating rate or any average heating rate disclosed herein is used in step (1), such as 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min) or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0175] Aspect 29. A process (for producing activated (calcined) chromium catalyst, said process) comprising (1) exposing a pre-catalyst in a fluidized bed vessel to a feed of a first diluting oxidizing gas at a temperature T2 in the range of 250℉ to 700℉ (121°C to 371°C) and at a temperature T3 up to and including in the range of 700℉ to 950℉ (371°C to 510°C), said first diluting oxidizing gas comprising 1 to 10% by volume of oxygen; and (2) heating the pre-catalyst to a temperature T4 in the range of 1000℉ to 1600℉ (538°C to 871°C) while introducing a third inert gas or a third oxidizing gas into said fluidized bed vessel, and holding the pre-catalyst at T4 in said third inert gas or said third oxidizing gas for a holding time t1 in the range of 1 hour to 15 hours.

[0176] Aspect 30. The process as defined in aspect 29, wherein any suitable heating rate or any average heating rate disclosed herein is used in step (1), such as 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min) or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0177] Aspect 31. The process as defined in Aspect 29 or 30, wherein the first diluting oxidizing gas contains any suitable oxygen volume percentage, such as 1 to 9 volume%, 1 to 8 volume%, 2 to 8 volume%, 2 to 7 volume%, or 3 to 6 volume%.

[0178] Aspect 32. The process as defined in any one of Aspects 24-31, the process further comprising, prior to step (1), loading the precatalyst in the fluidized bed vessel and heating the precatalyst in a first inert gas to a temperature T1.

[0179] Aspect 33. The process as defined in aspect 32, wherein the pre-catalyst is at a temperature of ambient temperature to 120℉ (49°C) before being loaded into the fluidized bed vessel.

[0180] Aspect 34. The process as defined in Aspect 32 or 33, wherein the precatalyst is loaded into the fluidized bed vessel in portions of 1 to 10 parts by amount of total precatalyst.

[0181] Aspect 35. The process as defined in aspect 34, wherein during each portion of the total amount of the pre-catalyst loaded, the temperature is maintained within a temperature range of 300℉ to 600℉ (149°C to 315°C) or 400℉ to 600℉ (204°C to 315°C).

[0182] Aspect 36. The process as defined in Aspect 34 or 35, wherein when the temperature drops below 400℉ (204°C) or below 300℉ (149°C), the loading of each portion of the total amount of the pre-catalyst is stopped.

[0183] Aspect 37. The process as defined in any of Aspects 34-36, wherein when the pressure rises above 1 psig, the loading of each portion of the total amount of the pre-catalyst is stopped.

[0184] Section 38. The process as defined in any of Sections 32-37, wherein T1 is within any suitable range or any range disclosed herein, such as 400℉ to 700℉ (204℃ to 371℃), 450℉ to 650℉ (232℃ to 343℃), or 500℉ to 600℉ (260℃ to 315℃).

[0185] Aspect 39. The process as defined in any of Aspects 24-38, wherein T2 is within any suitable range or any range disclosed herein, such as 400℉ to 600℉ (204℃ to 315℃), 600℉ to 700℉ (315℃ to 371℃), 500℉ to 650℉ (260℃ to 343℃), 625℉ to 700℉ (329℃ to 371℃) or 575℉ to 675℉ (302℃ to 357℃).

[0186] Aspect 40. The process as defined in any of Aspects 24-39, wherein T3 is within any suitable range or any range disclosed herein, such as 700℉ to 850℉ (371℃ to 454℃), 700℉ to 800℉ (371℃ to 427℃), 725℉ to 900℉ (385℃ to 482℃), 750℉ to 950℉ (399℃ to 510℃) or 750℉ to 850℉ (399℃ to 454℃).

[0187] Aspect 41. The process as defined in any of Aspects 24-40, wherein t1 is within any suitable range or any range disclosed herein, such as 1 hour to 8 hours, 2 hours to 10 hours, 3 hours to 15 hours, 3 hours to 8 hours or 4 hours to 6 hours.

[0188] Aspect 42. The process as defined in any of Aspects 24-41, wherein any suitable heating rate or any heating rate disclosed herein is used in step (2), such as 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min) or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

[0189] Aspect 43. The process as defined in any of Aspects 24-42, wherein T4 is within any suitable range or any range disclosed herein, such as 1000℉ to 1300℉ (538℃ to 704℃), 1100℉ to 1600℉ (593℃ to 871℃), 1100℉ to 1400℉ (593℃ to 760℃), 1100℉ to 1300℉ (593℃ to 704℃) or 1200℉ to 1300℉ (649℃ to 704℃).

[0190] Aspect 44. The process as defined in any of Aspects 24-43, the process further comprising, prior to step (1), determining whether an exothermic temperature rise occurs in the fluidized bed vessel (e.g., an rise of at least 30℉ (17°C) within 5 minutes or a positive second derivative of temperature with respect to time), and then proceeding to step (1).

[0191] Aspect 45. A process as defined in any one of Aspects 24-44, wherein the process further comprises the step of: (3) cooling the pre-catalyst to a temperature T5 in the range of 900℉ to 1200℉ (482°C to 649°C) while introducing a fourth inert gas into the fluidized bed vessel, wherein T5 is less than T4.

[0192] Aspect 46. The process as defined in aspect 44, wherein any suitable cooling rate or any cooling rate disclosed herein is used in step (3), such as 1℉ to 4℉ / min (0.6℃ to 2.2℃ / min), 1.5℉ to 3.5℉ / min (0.8℃ to 2℃ / min) or 2℉ to 3℉ / min (1℃ to 1.7℃ / min).

[0193] Aspect 47. The process as defined in aspect 45 or 46, wherein the process further comprises the step of: (4) exposing the pre-catalyst to a fourth oxidizing gas in the fluidized bed vessel at T5 for a duration t2 ranging from 30 minutes to 10 hours.

[0194] Aspect 48. The process as defined in aspect 47, wherein t2 is within any suitable range or any range disclosed herein, such as 30 minutes to 8 hours, 1 hour to 10 hours, 1 hour to 8 hours, 2 hours to 6 hours or 3 hours to 5 hours.

[0195] Aspect 49. The process as defined in Aspect 47 or 48, wherein t2 is a time period based on the amount of chromium on the activated (calcined) chromium catalyst sufficient to form at least 30 wt.%, at least 50 wt.%, at least 70 wt.%, or at least 80 wt.% of chromium (VI).

[0196] Aspect 50. The process as defined in any of Aspects 45-49, wherein T5 is within any suitable range or any range disclosed herein, such as 900℉ to 1100℉ (482℃ to 593℃), 950℉ to 1150℉ (510℃ to 621℃), 1000℉ to 1200℉ (538℃ to 649℃) or 1000℉ to 1100℉ (538℃ to 593℃).

[0197] Aspect 51. The process as defined in any one of Aspects 47-50, wherein the process further comprises the step of: (5) cooling to a temperature T6 in the range of 500℉ to 700℉ (260°C to 371°C) to produce the activated (calcined) chromium catalyst while introducing a fifth oxidizing gas into the fluidized bed vessel.

[0198] Aspect 52. The process as defined in aspect 51, wherein any suitable cooling rate or any cooling rate disclosed herein is used in step (5), such as 1℉ to 4℉ / min (0.6℃ to 2.2℃ / min), 1.5℉ to 3.5℉ / min (0.8℃ to 2℃ / min) or 2℉ to 3℉ / min (1℃ to 1.7℃ / min).

[0199] Aspect 53. The process as defined in aspect 51 or 52, wherein the process further comprises the step of: (6) purging the activated (calcined) chromium catalyst in the fluidized bed vessel at T6 in a fifth inert gas and cooling to ambient temperature.

[0200] Aspect 54. The process as defined in aspect 53, wherein in step (6), the activated (calcined) chromium catalyst is purged with the fifth inert gas at T6 for a continuous purging time t3, wherein t3 is in any suitable range or in any range disclosed herein, such as 2 minutes to 20 hours, 5 minutes to 12 hours, 5 minutes to 5 hours, 15 minutes to 4 hours or 30 minutes to 6 hours.

[0201] Section 55. The process as defined in any of Sections 51-54, wherein T6 is within any suitable range or any range disclosed herein, such as 500℉ to 650℉ (260℃ to 343℃), 550℉ to 700℉ (288℃ to 371℃), 550℉ to 650℉ (288℃ to 343℃), or 600℉ to 675℉ (315℃ to 357℃).

[0202] Aspect 56. The process as defined in any of Aspects 51-55, wherein T6 is within 150℉ (83℃), 100℉ (56℃), 50℉ (28℃), 25℉ (14℃) or 10℉ (6℃) of T1.

[0203] Aspect 57. A process as defined in any one of Aspects 24-56, wherein the first inert gas, the third inert gas, the fourth inert gas and the fifth inert gas are the same or different and independently comprise (or substantially consist of, or consist of) nitrogen, argon or a combination thereof.

[0204] Aspect 58. A process as defined in any one of Aspects 24-57, wherein the first oxidizing gas, the third oxidizing gas, the fourth oxidizing gas, and the fifth oxidizing gas are the same or different and independently comprise (or substantially consist of, or consist of) oxygen, air, a mixture of oxygen and an inert gas (e.g., nitrogen), a mixture of air and an inert gas (e.g., nitrogen), or a combination thereof, having any suitable oxygen volume percentage, for example 1 to 40 volume%, 1 to 30 volume%, 2 to 21 volume%, 3 to 25 volume%, or 4 to 10 volume%.

[0205] Aspect 59. A process as defined in any of Aspects 24-58, wherein, when measured by MI, HLMI or both, the melt index potential of the activated (calcined) catalyst is greater than the melt index potential of an otherwise identical catalyst (or control catalyst) activated by exposure to an oxidizing atmosphere at a temperature of 1200℉ (649°C) for a period of 3 hours (or 8 hours) (greater than any suitable amount or any amount disclosed herein, such as at least 10%, at least 25%, at least 50%, at least 75% or at least 100%).

[0206] Aspect 60. A process as defined in any one of Aspects 24-59, wherein the activated (calcined) catalyst produces a polymer under standard polymerization conditions, the polymer having a Mw / Mn ratio (or Mz / Mw ratio, or CY-a parameter) within 35% (or within 30%, 25%, 20%, 15%, 10%, or 5%) of the Mw / Mn ratio (or Mz / Mw ratio, or CY-a parameter) of the polymer produced by exposure to an oxidizing atmosphere at a temperature of 1200℉ (649°C) for a period of 3 hours (or 8 hours) of continuous exposure to an oxidizing atmosphere.

[0207] Aspect 61. A process as defined in any one of Aspects 24-60, wherein the activated (calcined) catalyst has an MI potential of at least 0.2, at least 0.3, at least 0.4, at least 0.5, at least 0.6, at least 0.7, at least 0.8, at least 0.9, at least 1 or at least 1.2 g / 10 min.

[0208] Aspect 62. A process as defined in any one of Aspects 24-61, wherein the activated (calcined) catalyst has an HLMI potential of at least 20, at least 25, at least 30, at least 35, at least 40, at least 50, at least 60, at least 70, at least 80 or at least 100 g / 10 min.

[0209] Aspect 63. A process as defined in any one of Aspects 24-62, wherein the activated (calcined) catalyst produces a polymer under standard polymerization conditions, the polymer having a per ft 2 A 25-micrometer thick film contains less than or equal to 100 gels (or per ft) 2 The total number of membrane gels (or catalyst particle gel count) of a 25-micrometer thick membrane (less than or equal to 80, or less than or equal to 60, or less than or equal to 40, or less than or equal to 30, or less than or equal to 20, or less than or equal to 10, or less than or equal to 5 gels), wherein the membrane gels include those with a size greater than 200 μm (and for the catalyst particle gel count, caused by the catalyst particles).

[0210] Aspect 64. A process as defined in any of Aspects 24-63, wherein the pre-catalyst (or the activated catalyst) is contacted with the gas stream in the fluidized bed vessel (batch or continuously) at any suitable linear velocity or any linear velocity disclosed herein, such linear velocity as 0.05 to 0.6 ft / sec, 0.05 to 0.3 ft / sec, 0.1 to 0.4 ft / sec, 0.2 to 0.5 ft / sec, 0.2 to 0.4 ft / sec, or 0.2 to 0.3 ft / sec.

[0211] Aspect 65. A process as defined in any of Aspects 24-64, wherein the pre-catalyst (or the activated chromium catalyst) comprises a silica support and chromium in any suitable amount or within any range disclosed herein, based on the weight of the respective catalyst, such as 0.1 to 5 wt.%, 0.2 to 5 wt.%, 0.5 to 3 wt.%, 0.5 to 2 wt.%, or 0.5 to 1.5 wt.%.

[0212] Aspect 66. The process as defined in aspect 65, wherein the pre-catalyst (or the activated chromium catalyst) further comprises any suitable amount or within any range disclosed herein of titanium, such as 0.1 to 10 wt.%, 0.5 to 10 wt.%, 1 to 10 wt.%, 2 to 8 wt.%, or 2 to 6 wt.% of titanium.

[0213] Aspect 67. The process as defined in aspect 66, wherein the pre-catalyst (or the activated chromium catalyst) further comprises nitrogen in any suitable amount or in any range disclosed herein, such as 1 to 5, 1.5 to 5, 1.5 to 4.5, 2 to 5, 2 to 4 or 2 to 3 mol nitrogen / mol titanium.

[0214] Aspect 68. The process as defined in Aspect 66 or 67, wherein the pre-catalyst further comprises any suitable amount or within any range disclosed herein of a carboxyl group / ligand, such as 1 to 5, 1 to 4, 1 to 3, 1.5 to 5, 1.5 to 4 or 2 to 3 mol carboxyl group / mol titanium.

[0215] Aspect 69. A process as defined in any of Aspects 65-68, wherein the pre-catalyst further comprises carbon, based on the weight of the catalyst, in any suitable amount or within any range disclosed herein, such as 0.5 to 10 wt.%, 1 to 10 wt.%, 1 to 5 wt.%, 2 to 10 wt.%, 2 to 8 wt.%, or 2 to 6 wt.%.

[0216] Aspect 70. The process as defined in any one of Aspects 65-69, wherein the amount of chromium in the pre-catalyst in a +5 oxidation state or lower is at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.%, based on the total amount of chromium on the pre-catalyst.

[0217] Aspect 71. The process as defined in any one of Aspects 65-70, wherein the amount of chromium in the activated chromium catalyst in the hexavalent oxidation state is at least 40 wt.%, at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, or at least 95 wt.%, based on the total amount of chromium on the activated chromium catalyst.

[0218] Aspect 72. A process as defined in any of Aspects 24-71, wherein the pre-catalyst (or the silica support, or the activated chromium catalyst) has any suitable pore volume (total) or a pore volume (total) within any range disclosed herein, such as 0.5 to 5 mL / g, 1 to 5 mL / g, 1 to 3 mL / g, or 1.5 to 2 mL / g.

[0219] Aspect 73. A process as defined in any one of Aspects 24-72, wherein the pre-catalyst (or the silica support, or the activated chromium catalyst) has any suitable BET surface area or a BET surface area within any range disclosed herein, for example, 100 to 700 m². 2 / g, 200 to 600 m 2 / g, 250 to 550 m 2 / g or 300 to 500 m 2 / g.

[0220] Aspect 74. A process as defined in any of Aspects 24-73, wherein the pre-catalyst (or the silica support, or the activated chromium catalyst) has any suitable average (d50) particle size or an average (d50) particle size within any range disclosed herein, such as 10 to 500 micrometers, 30 to 130 micrometers, or 40 to 70 micrometers.

[0221] Aspect 75. An olefin polymerization process comprising (I) carrying out a process for producing the activated (calcined) chromium catalyst as defined in any one of aspects 24-74, and (II) contacting the activated (calcined) chromium catalyst and optionally a co-catalyst with an olefin monomer and optionally an olefin comonomer in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

[0222] Aspect 76. An olefin polymerization process as defined in aspect 75, wherein a co-catalyst is used, and said co-catalyst comprises any suitable co-catalyst or any co-catalyst disclosed herein, such as an aluminoxane co-catalyst, an organoaluminum co-catalyst, or an organoboron co-catalyst or any combination thereof.

[0223] Aspect 77. An olefin polymerization process as defined in Aspect 75 or 76, wherein the olefin monomer and the optional olefin comonomer independently comprise C2-C. 20 α-olefins.

[0224] Aspect 78. An olefin polymerization process as defined in any one of Aspects 75-77, wherein the olefin monomer comprises ethylene.

[0225] Aspect 79. An olefin polymerization process as defined in any one of Aspects 75-78, wherein the activated chromium catalyst is contacted with ethylene and an olefin comonomer, the olefin comonomer comprising C3-C4. 10 α-olefins.

[0226] Aspect 80. An olefin polymerization process as defined in any one of Aspects 75-79, wherein the activated chromium catalyst is contacted with ethylene and an olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.

[0227] Aspect 81. An olefin polymerization process as defined in any one of Aspects 75-80, wherein the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof.

[0228] Aspect 82. An olefin polymerization process as defined in any one of Aspects 75-81, wherein the polymerization reactor system comprises a circulating slurry reactor.

[0229] Aspect 83. An olefin polymerization process as defined in any one of Aspects 75-82, wherein the polymerization reactor system comprises a single reactor.

[0230] Aspect 84. An olefin polymerization process as described in any one of Aspects 75-82, wherein the polymerization reactor system comprises two reactors.

[0231] Aspect 85. An olefin polymerization process as defined in any one of Aspects 75-82, wherein the polymerization reactor system comprises more than two reactors.

[0232] Aspect 86. An olefin polymerization process as defined in any of aspects 75-85, wherein the olefin polymer comprises any olefin polymer disclosed herein.

[0233] Aspect 87. An olefin polymerization process as defined in any one of Aspects 75-86, wherein the olefin polymer comprises ethylene homopolymer, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer and / or ethylene / 1-octene copolymer.

[0234] Aspect 88. An olefin polymerization process as defined in any one of Aspects 75-87, wherein the polymerization conditions include a polymerization reaction temperature in the range of 60°C to 120°C and a reaction pressure in the range of 200 to 1000 psig (1.4 to 6.9 MPa).

[0235] Aspect 89. An olefin polymerization process as defined in any of Aspects 75-88, wherein the polymerization conditions are substantially constant, for example, for a particular polymer grade.

[0236] Aspect 90. An olefin polymerization process as defined in any one of Aspects 75-89, wherein no hydrogen is added to the polymerization reactor system.

[0237] Aspect 91. An olefin polymerization process as defined in any one of Aspects 75-89, wherein hydrogen is added to the polymerization reactor system.

[0238] Aspect 92. An olefin polymerization process as defined in any one of Aspects 75-91, wherein the process is carried out in a commercial circulating reactor at a productivity of 2,000 to 5,000 g of polymer per gram of catalyst and / or a space-time yield greater than or equal to 2, 2.5, 2.8, 3 or 4 (lb / hr) / gal and / or less than or equal to 6, 5.5 or 5 (lb / hr) / gal to produce an ethylene / 1-hexene copolymer with a density of at least 0.947 g / cc as determined according to ISO 1183 Part 2.

[0239] Aspect 93. An olefin polymerization process as defined in any one of Aspects 75-91, wherein the process is carried out in a commercial circulating reactor at a productivity of 2,000 to 5,000 g of polymer per gram of catalyst and / or a space-time yield of greater than or equal to 2, 2.5, 2.8, 3 or 4 (lb / hr) / gal and / or less than or equal to 6, 5.5 or 5 (lb / hr) / gal to produce an ethylene / 1-hexene copolymer with a density of at least 0.938 g / cc as determined according to ISO 1183 Part 2.

Claims

1. An activation system comprising: (a) A fluidized bed container having one or more heating zones and configured to fluidize and activate a supported chromium precatalyst; (b) One or more fluidizing gas inlets configured to introduce fluidizing gas into the fluidized bed container, the fluidizing gas comprising (i) an inert gas, (ii) an oxygen-containing gas, or (iii) a mixture of an inert gas and an oxygen-containing gas; (c) One or more thermocouples positioned inside the fluidized bed vessel for measuring the activation temperature inside the fluidized bed vessel; and (d) A controller configured to circulate or regulate (iii) a mixture of the inert gas and the oxygen-containing gas between (i) the inert gas and (ii) the oxygen-containing gas based on a time interval and / or based on the activation temperature measured by the one or more thermocouples.

2. The system of claim 1, wherein: The one or more fluidized gas inlets include an inert gas inlet line and an oxygen-containing gas inlet line; and The controller is further configured to cycle between: (1) The inert gas is introduced into the fluidized bed container through the inert gas inlet pipeline by opening the first valve on the inert gas inlet pipeline and closing the second valve on the oxygen-containing gas inlet pipeline; as well as (2) The oxygen-containing gas is introduced into the fluidized bed container through the oxygen-containing gas inlet pipeline by opening the second valve and closing the first valve.

3. The system of claim 1, wherein: The one or more fluidizing gas inlets include a single fluidizing gas inlet; and The controller is further configured to cycle between: (1) The inert gas is introduced into the fluidizing gas inlet through the inert gas inlet pipeline by opening the first valve on the inert gas inlet pipeline and closing the second valve on the oxygen-containing gas inlet pipeline; as well as (2) The oxygen-containing gas is introduced into the fluidizing gas inlet through the oxygen-containing gas inlet pipeline by opening the second valve and closing the first valve.

4. The system of any one of claims 1-3, wherein the controller is further configured to: The duration of feeding the inert gas independently within the ranges of 10 seconds to 15 minutes, 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, or 20 seconds to 2 minutes, and the duration of feeding the oxygen-containing gas independently within the ranges of 10 seconds to 15 minutes, 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, 20 seconds to 2 minutes, or 20 seconds to 1 minute, can be adjusted. The average duration of feeding the inert gas is adjusted to be greater than the average duration of feeding the oxygen-containing gas; The circulation of the inert gas and the oxygen-containing gas is adjusted to maintain an average increase in the activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min) within a temperature range from a lower temperature range of 250℉ to 700℉ (121℃ to 371℃ / min) to a higher temperature range of 700℉ to 950℉ (371℃ to 510℃ / min); The number of cycles of introducing the inert gas followed by the oxygen-containing gas is adjusted to the range of 5 to 50, 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25, or 10 to 20; or Any combination thereof.

5. The system as described in any one of claims 1-4, wherein: The inert gas includes nitrogen; The oxygen-containing gas includes air; The fluidized bed container has two or more heating zones; The system includes two or more thermocouples; or Any combination thereof.

6. The system of any one of claims 1-5, wherein the one or more fluidizing gas inlets are configured to introduce the fluidizing gas into the fluidized bed vessel at a linear velocity of 0.05 to 0.6 ft / sec, 0.05 to 0.3 ft / sec, 0.1 to 0.4 ft / sec, 0.2 to 0.5 ft / sec, 0.2 to 0.4 ft / sec, or 0.2 to 0.3 ft / sec.

7. The system of claim 1, wherein: The one or more fluidizing gas inlets include a single fluidizing gas inlet; and The controller is further configured to adjust the mixture of inert gas and oxygen-containing gas in the fluidized gas inlet by controlling a first flow rate of the inert gas entering the fluidized gas inlet through the inert gas inlet line and a second flow rate of the oxygen-containing gas entering the fluidized gas inlet through the oxygen-containing gas inlet line.

8. The system of claim 7, wherein the controller is further configured to: The relative amounts of the inert gas and the oxygen-containing gas in the mixture, controlled at 1 to 10 vol%, 1 to 8 vol%, 2 to 8 vol%, 2 to 7 vol%, or 3 to 6 vol% of oxygen by volume; and The mixture of the inert gas and the oxygen-containing gas is adjusted to maintain an average increase in the activation temperature of 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min) within a temperature range from a lower temperature range of 250℉ to 700℉ (121℃ to 371℃ / min) to a higher temperature range of 700℉ to 950℉ (371℃ to 510℃ / min).

9. The system of any one of claims 1-8, wherein the controller is further configured to determine an exothermic increase in the activation temperature measured by the one or more thermocouples.

10. A process comprising: (1) The pre-catalyst in the fluidized bed vessel is exposed to a feed cycle of a second oxidizing gas and a second inert gas at a temperature T2 ranging from 250℉ to 700℉ (121℃ to 371℃) to a temperature T3 ranging from 700℉ to 950℉ (371℃ to 510℃), wherein: The duration of each second oxidizing gas feed cycle is independently between 10 seconds and 15 minutes; The duration of each second inert gas feed cycle is independently between 10 seconds and 15 minutes; The average duration of the second oxidizing gas feed cycle is less than the average duration of the second inert gas feed cycle; and The average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min); and (2) While introducing the third inert gas or the third oxidizing gas into the fluidized bed container, the precatalyst is heated to a temperature T4 in the range of 1000℉ to 1600℉ (538℃ to 871℃), and the precatalyst is held in the third inert gas or the third oxidizing gas at T4 for a holding time t1 in the range of 1 hour to 15 hours.

11. The process of claim 10, wherein: The duration of each second oxidizing gas feed cycle is independently 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, 20 seconds to 2 minutes, or 20 seconds to 1 minute; and / or The duration of each second inert gas feed cycle is independently 10 seconds to 5 minutes, 10 seconds to 1 minute, 1 minute to 10 minutes, 1 minute to 5 minutes, 20 seconds to 10 minutes, or 20 seconds to 2 minutes.

12. The process of claim 10 or 11, wherein: Step (1) includes 5 to 50, 5 to 40, 5 to 30, 6 to 50, 6 to 40, 6 to 25, 7 to 40, 7 to 25, 10 to 50, 10 to 25, or 10 to 20 cycles; and / or The average heating rate in step (1) is 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min) or 2℉ to 3.5℉ / min (1℃ to 2℃ / min).

13. A process comprising: (1) The pre-catalyst in the fluidized bed vessel is exposed to the feed of the first diluting oxidizing gas at a temperature T2 ranging from 250℉ to 700℉ (121℃ to 371℃) and at a temperature T3 ranging from 700℉ to 950℉ (371℃ to 510℃). The first diluting oxidizing gas contains 1 to 10% by volume oxygen; as well as (2) While introducing the third inert gas or the third oxidizing gas into the fluidized bed container, the precatalyst is heated to a temperature T4 in the range of 1000℉ to 1600℉ (538℃ to 871℃), and the precatalyst is held in the third inert gas or the third oxidizing gas at T4 for a holding time t1 in the range of 1 hour to 15 hours.

14. The process of claim 13, wherein: The average heating rate in step (1) is 0.5℉ to 10℉ / min (0.3℃ to 6℃ / min), 1℉ to 5℉ / min (0.6℃ to 3℃ / min), 1.5℉ to 4℉ / min (0.8℃ to 2.2℃ / min), or 2℉ to 3.5℉ / min (1℃ to 2℃ / min); and The first diluted oxidizing gas contains 1 to 9 vol%, 1 to 8 vol%, 2 to 8 vol%, 2 to 7 vol%, or 3 to 6 vol% oxygen.

15. The process according to any one of claims 10-14, the process further comprising, prior to step (1), loading the precatalyst in the fluidized bed vessel and heating the precatalyst in a first inert gas to a temperature T1.

16. The process according to any one of claims 10-15, the process further comprising, prior to step (1), determining whether an exothermic temperature rise occurs in the fluidized bed vessel, and then proceeding to step (1).

17. The process of any one of claims 10-16, wherein the process further comprises the following step: (3) While introducing the fourth inert gas into the fluidized bed container, the pre-catalyst is cooled to a temperature T5 in the range of 900℉ to 1200℉ (482℃ to 649℃), wherein T5 is less than T4.

18. The process of claim 17, wherein the process further comprises the following step: (4) The pre-catalyst is exposed to the fourth oxidizing gas in the fluidized bed vessel at T5 for a duration t2 ranging from 30 minutes to 10 hours.

19. The process of claim 18, wherein the process further comprises the following step: (5) While introducing the fifth oxidizing gas into the fluidized bed vessel, the temperature is cooled to a temperature T6 in the range of 500℉ to 700℉ (260℃ to 371℃) to produce an activated chromium catalyst.

20. The process of claim 19, wherein the process further comprises the following step: (6) The activated chromium catalyst is purged in a fifth inert gas at T6 in the fluidized bed vessel and cooled to ambient temperature.

21. The process of any one of claims 10-20, wherein the precatalyst comprises: Silicon dioxide; 0.1 to 5 wt.% chromium; and Optionally, 0.1 to 10 wt.% titanium.

22. An olefin polymerization process, comprising: (I) Performing the process described in any one of claims 19-21; as well as (II) The activated chromium catalyst and optional co-catalyst are contacted with olefin monomers and optional olefin comonomers in a polymerization reactor system under polymerization conditions to produce an olefin polymer.

23. The process of claim 22, wherein the olefin monomer comprises ethylene.

24. The process of claim 22, wherein the activated chromium catalyst is contacted with ethylene and an olefin comonomer, the olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a mixture thereof.

25. The process of any one of claims 22-24, wherein the polymerization reactor system comprises a slurry reactor, a gas-phase reactor, a solution reactor, or a combination thereof.

26. The process of any one of claims 22-25, wherein the polymerization reactor system comprises a circulating slurry reactor.

27. The process of any one of claims 22-26, wherein the olefin polymer comprises ethylene homopolymer, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer and / or ethylene / 1-octene copolymer.

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