Thermal conversion of heavy hydrocarbons into intermediate phase pitch

Abstract

A method for producing intermediate phase pitch, comprising: providing a feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃); heating the feedstock at a temperature of at least 450℃ to produce a heat-treated product comprising intermediate phase pitch, wherein the heating is performed under reaction conditions sufficient to have an equivalent reaction time of at least 1,000 seconds; and recovering the intermediate phase pitch.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims the benefit and priority of U.S. Provisional Application No. 63 / 172340 filed on April 8, 2021, the disclosures of which are incorporated herein by reference.

[0003] Related applications

[0004] The present disclosure is technically related to U.S. provisional patent application 63 / 138,051 filed on January 15, 2021, the entire contents of which are incorporated herein by reference.

[0005] field

[0006] The present disclosure relates to the production of intermediate pitch typically used in carbon fiber production. Background Technology

[0007] Isotropic pitch and mesophase pitch are carbon-containing feedstocks that can be formed from residues generated during the processing of coal or petroleum feedstocks, or by other methods such as the acid-catalyzed condensation of small aromatic species. For some grades of carbon fibers, isotropic pitch can be used as an initial feedstock. However, carbon fibers produced from isotropic pitch generally have little molecular orientation and relatively poor mechanical properties. In contrast to carbon fibers formed from isotropic pitch, carbon fibers produced from mesophase pitch exhibit highly desirable molecular orientation and relatively excellent mechanical properties.

[0008] Typically, intermediate-phase pitch can be produced by thermally converting heavy aromatic hydrocarbons into isotropic pitch in a visbreaker at medium and high pressures (> 400°C and > 300 psi), followed by sequential isopitch separation using a wiped-out film evaporator. The isotropic pitch is converted into the intermediate phase at > 420°C in batch mode under full vacuum with long residence times, e.g., > 6 hours. The batch process is difficult to scale up due to temperature non-uniformity and the high likelihood of coke formation in large autoclaves. Current state-of-the-art technology is typically limited to a size of about 100 gal. The inefficient batch process results in high production costs for the intermediate phase.

[0009] The purpose of isopitch formation in the intermediate phase production process is to generate and concentrate carbonaceous species, namely micro carbon residue (MCR), which can potentially serve as intermediate phase precursors. The autoclave process for intermediate phase production is typically executed at temperatures exceeding 425°C, with long residence times, low hydrocarbon partial pressures, and often under vacuum. Consequently, the cost of producing the intermediate phase is very high, which inevitably results in expensive pitch-based carbon fibers.

[0010] Despite their exceptionally high performance compared to steel, pitch-based carbon fiber is limited to niche applications such as satellites, sports equipment, and rocket engine nozzles primarily due to the high cost of intermediate production.

[0011] U.S. Patent 4,208,267 describes a method for forming an intermediate phase pitch. An isotropic pitch sample is solvent-extracted. Subsequently, the extract is exposed to an elevated temperature in the range of 230°C to about 400°C to form an intermediate phase pitch.

[0012] U.S. Patent 5,032,250 describes a process for isolating intermediate phase pitch. When isotropic pitch containing mesogen is combined with a solvent and treated under dense phase or supercritical conditions, the mesogen is phase-separated.

[0013] U.S. Patent 5,259,947 describes a method for forming a dissolved intermediate phase, comprising the steps of: (1) combining a carbonaceous aromatic isotropic pitch with a solvent; (2) applying sufficient stirring and sufficient heat to form a liquid solvation intermediate phase droplet in which an insoluble substance in the combination is suspended; and (3) recovering the insoluble substance as a solid or liquid solvation intermediate phase.

[0014] U.S. Patent Publication 2019 / 0078023 describes upgrading crude oil and oil residues to produce intermediate phase pitch and additional petrochemicals in an integrated process.

[0015] Other potential references of interest include U.S. Patent 4,518,483, U.S. Patent 9,222,027, U.S. Patent Publication 2019 / 0382665, and U.S. Patent Publication 2020 / 0181497. Brief explanation of the drawing

[0016] Figure 1 illustrates an exemplary process and system for intermediate production. Figure 2 is an image of a solid product produced by an embodiment of current technological development. Figure 3 is an image of a solid product produced by an embodiment of current technological development. Specific details for implementing the invention

[0017] summation

[0018] A process for manufacturing intermediate phase pitch, the process comprises the steps of: providing a feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃); heating the feedstock at a temperature of at least 450℃ to produce a heat-treated product containing intermediate phase pitch, wherein the heating is performed under reaction conditions sufficient to have an equivalent reaction time of at least 1,000 seconds; and recovering the intermediate phase pitch.

[0019] In the process, the temperature may be less than 600℃.

[0020] In the process, the feedstock may have a hydrogen content of 5.5 to 10 weight percent.

[0021] In the process, heating is the only heating step applied to the feedstock to produce the intermediate phase pitch.

[0022] The process may additionally include a step of injecting steam into a reactor where heating occurs.

[0023] The process may additionally include a step of injecting steam into the feedstock when the feedstock is supplied to the reactor.

[0024] The process may further include a step of injecting steam into a heat-treated product containing an intermediate phase pitch product from a reactor in which heating occurs.

[0025] In the process, the yield of intermediate pitch may exceed 1 weight%.

[0026] In the process, the yield of the intermediate phase pitch may be in the range of 10 weight% to 50 weight%.

[0027] In the process, the yield of the intermediate phase pitch may be in the range of 10 weight% to 60 weight%.

[0028] In the process, reaction conditions may include an inert atmosphere, a temperature in the range of 450°C to 520°C, and a pressure in the range of 500 to 1,500 psig.

[0029] In the process, X is the equivalent reaction time (ERT) of heating, Y is the bromine number of the feedstock as measured according to ASTM D1159, and heating is performed under reaction conditions sufficient to satisfy the relationship [X*Y] ≥ 31,000 seconds.

[0030] The process may additionally include a step of controlling the temperature of the heating step so that the equivalent reaction time exceeds 1,000 seconds.

[0031] The process may include a feedstock comprising a fraction having a boiling point ≥ 1,050℉ (566℃) and ranging from about 1% by weight to about 40% by weight based on the weight of the feedstock.

[0032] In the process, the feedstock may include at least one member selected from the group consisting of main column bottoms (MCB), hydrogenated MCB, steam cracker tar, hydrogenated steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum residue, asphalt-removed residue or rock, and mixtures or combinations thereof.

[0033] In the process, the step of recovering intermediate phase pitch may include separating intermediate phase pitch from light hydrocarbons.

[0034] In the process, heating can be performed in a reactor, and the process further includes a step of controlling the liquid line velocity in the reactor so that the intermediate phase precursor becomes a slurry.

[0035] In the process, control may include steam injection.

[0036] A system comprising: a reactor configured to receive a feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃) and to heat the feedstock at a temperature of at least 450℃ to produce a heat-treated product containing intermediate phase pitch, wherein the reactor is configured to heat the feedstock under reaction conditions sufficient to have an equivalent reaction time of at least 1,000 seconds; and a separation device fluidly connected to the reactor, wherein the separation device is configured to separate intermediate phase pitch from the effluent received from the reactor.

[0037] The system may additionally include a steam injector configured to inject steam into the reactor, into the effluent, and / or into the feedstock.

[0038] In the above system, the separator may be a cyclone separation device.

[0039] In the system, the separator can be an asphalt remover.

[0040] details

[0041] Unexpectedly, it was discovered that intermediate phase pitch can be produced from slurry oil in a single thermal stage. This unexpected result opens up the possibility of a continuous one-stage thermal process for intermediate phase pitch, as illustrated in Fig. 1. An embodiment of current technological advancements may utilize a single thermal stage using a continuous flow tubular reactor at an operating pressure exceeding 400 psig (measured at the reactor inlet). Compared to conventional processes, tubular reactors operate at higher temperatures but with shorter residence times to mitigate coking while matching run severity. For example, a continuous tubular reactor operating at 500°C with a residence time of 15 minutes is equivalent to 4,000 equivalent superseverity. Steam co-feeding into the tubular reactor may be used before reactor input or after production from the reactor. Separation devices, such as a cyclone via gravity separation or a DAU (Asphalt Removal Unit) via solubility, can separate the intermediate phase from light hydrocarbons and steam.

[0042] The intermediate phase can be produced through a one-step thermal process different from the two-step process mentioned in the background section. Feedstocks having a relatively higher H content (i.e., 5.5 wt% to 10 wt%, preferably 7 to 8 wt%) than the isopitch (i.e., 5 to 6 wt%), such as the main column bottom (MCB), can be directly converted into the intermediate phase at an elevated temperature. An exemplary embodiment of current technological advancements may include (1) heat-treating the feedstock under harsher conditions than typical visbreakering conditions; (2) setting the pressure constant (or substantially constant with fluctuations not exceeding + / - 10%) during the reaction that induces stripping of the light distillate from the reactor vessel; and (3) allowing sufficient aromatic polymerization to form an aligned intermediate phase that is anisotropic and measurable by a polarizing microscope due to intrinsic birefringence; (4) For example, the intermediate phase is separated from the light hydrocarbon using a cyclone, or in the case of a batch process, the intermediate phase is recovered by simply decanting the liquid product.

[0043] Various embodiments described herein provide a process for producing intermediate-phase pitch from a heavy feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃). However, other feedstocks from MCB may be used with current technological advancements.

[0044] Generally, a single heat treatment of a heavy feedstock is performed at a temperature range of about 450°C to about 520°C and a residence time of 5 minutes to 8 hours, more preferably about 3 hours to about 6 hours, more preferably 5 minutes to 1 hour, e.g. about 10 minutes to about 60 minutes (or 1 hour), most preferably 5 minutes to 30 minutes.

[0045] All numerical values ​​within the detailed description and claims herein are modified by "approximately" or "roughly" to account for experimental errors and variations that may be expected by those skilled in the art. Unless otherwise indicated, room temperature is approximately 23°C.

[0046] As used herein, “weight%” means weight percentage, “volume%” means volume percentage, “molar%” means mole percentage, “ppm” means parts per million, and “ppm wt” and “wppm” are used interchangeably to mean parts per million by weight. All “ppm” used herein refers to ppm by weight unless otherwise specified. All concentrations in this invention are expressed based on the total amount of the corresponding composition. All ranges expressed herein must include both endpoints as two specific embodiments unless otherwise specified or indicated.

[0047] definition

[0048] For the purposes of this specification and the appended claims, the following terms are defined.

[0049] As used herein, the terms “equivalent reaction time” or “equivalent residence time (ERT)” refer to the severity of work expressed in seconds as the residence time for a reaction with an activation energy of 54 kcal / mol in a reactor operating at 468°C. The ERT of the work is calculated as follows:

[0050]

[0051] Here, W is the work dwell time (seconds); e is 2.71828; and E a is 225,936 J / mol and R is 8.3145 J·mol -1 ㆍK -1 Igo; T rxnERT is the operating temperature expressed in Kelvin. In very general terms, the reaction rate doubles for every 12 to 13°C increase in temperature. Therefore, a residence time of 60 seconds at 468°C is equivalent to 60 ERT, and increasing the temperature to 501°C increases the operation fivefold, i.e., to 300 ERT. Expressed in another way, 300 seconds at 468°C is equivalent to 60 seconds at 501°C, and the same product mixture and distribution should be obtainable under both setting conditions.

[0052] As used herein, the term “pitch” refers to a viscoelastic carbonaceous residue obtained from the distillation of petroleum, coal tar, or an organic substrate. Unless otherwise specified herein, the term “pitch” refers to petroleum pitch (i.e., pitch obtained by distilling petroleum).

[0053] As used herein, the term "isotropic pitch" refers to a pitch containing unaligned molecules in an optically aligned liquid crystal.

[0054] As used herein, the term “main column bottom (MCB)" refers to the bottom fraction from the flow catalytic cracking process. More specifically, MCB refers to the fraction of the product of the catalytic cracking process that boils in the range of about 200°C to 650°C. However, the boiling point range may vary depending on operating conditions.

[0055] As used herein, the terms “intermediate phase pitch” or “intermediate phase” refer to a pitch that is a structurally aligned optically anisotropic liquid crystal. The intermediate phase structure may be described and characterized by various techniques such as optical birefringence, light scattering, or other scattering techniques.

[0056] Test method

[0057] Intermediate phase pitch content via optical microscope

[0058] Unless otherwise specified herein, the intermediate phase pitch content of a sample is determined by an optical microscope according to the following procedure. A digital image of the sample is generated using an optical microscope. Subsequently, a histogram of the total pixel count of the digital image is prepared by color intensity, and areas of brighter intensity due to high refractive index correspond to the intermediate phase pitch. The image is divided into intermediate phase pitch areas and non-intermediate phase pitch areas through thresholding, with areas having an intensity below a specific threshold corresponding to the intermediate phase pitch. Subsequently, an estimate of the sample's intermediate phase pitch content in area % (this result can then be extrapolated to correspond to an estimate in volume %) is obtained by subtracting the non-intermediate phase pitch area of ​​the image and then dividing the total amount of the intermediate phase pitch area of ​​the image by the total area of ​​the image.

[0059] Specific aspects of the present invention will now be described in more detail. Although the following description relates to specific aspects, those skilled in the art will understand that they are merely illustrative and that the present invention may be practiced in other ways. References to "invention" may refer to one or more of the inventions defined by the claims, but not all of them. The use of titles is for convenience only and should not be construed as limiting the scope of the present invention to specific aspects.

[0060] heavy feedstock

[0061] In the process of the present disclosure, the heavy feedstock may be characterized by a boiling range. One option for defining the boiling range is to use the initial boiling point and / or the final boiling point for the feedstock. Another option, which may provide a more representative description of the feedstock in some cases, is to characterize the feedstock based on the amount of feedstock boiling at one or more temperatures. For example, the “T5” boiling point for the feedstock is defined as the temperature at which 5% by weight of the feedstock boils off. Similarly, the “T95” boiling point is the temperature at which 95% by weight of the feedstock boils off. The percentage of feedstock boiling at a given temperature may be determined, for example, by the method specified in ASTM D2887 (or by the method of ASTM D7169 if ASTM D2887 is not suitable for the particular fraction). Generally, the heavy feedstock may have T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃). Examples of such heavy feedstocks include feedstocks having a 1,050°F+ (566°C+) fraction. In some aspects, the 566°C+ fraction may correspond to 1% or more by weight of the heavy feedstock (i.e., T99 above 566°C) or 2% or more by weight (T98 above 566°C) or 10% or more by weight (T90 above 566°C) or 15% or more by weight (T85 above 566°C) or 30% or more by weight (T70 above 566°C) or 40% or more by weight (T60 above 566°C), for example, about 1% to about 40% by weight or about 2% to about 30% by weight.

[0062] The heavy feedstock of the present disclosure may be characterized by reactivity when measured by its bromine number. The heavy feedstock of the present disclosure may have a bromine number ≥3, or ≥5, or ≥10, or ≥30, or about ≥40, e.g., about 3 to about 50, or about 5 to about 40, or about 10 to about 30, when measured according to ASTM D1159.

[0063] The heavy feedstock of the present disclosure may be characterized by an aromatic content. The heavy feedstock of the present disclosure may contain aromatic carbon of about 40 mol% or more, or about 50 mol% or more, or about 60 mol% or more, e.g., up to about 75 mol% or possibly much higher. The aromatic carbon content of the heavy feedstock may be determined according to ASTM D5186.

[0064] The heavy feedstock of the present disclosure may be characterized by an average number of carbon atoms. The heavy feedstock of the present disclosure may be composed of hydrocarbons having an average number of carbon atoms of about 33 to about 45 (e.g., about 35 to about 40, or about 37 to about 42, or about 40 to about 45).

[0065] The heavy feedstock of the present disclosure may be characterized by fine carbon residue (MCR) as determined by ASTM D4530-15. The heavy feedstock of the present disclosure may have an MCR of about 5 wt% or more (e.g., about 5 wt% to about 45 wt%, or about 10 wt% to about 45 wt%).

[0066] The heavy feedstock of the present disclosure may be characterized by a hydrogen content. The heavy feedstock of the present disclosure generally has a hydrogen content of about 6 weight% to about 11 weight%, e.g., about 6 weight% to about 10 weight%, or about 7 weight% to about 8 weight%.

[0067] The heavy feedstock of the present disclosure may be characterized by a cumulative concentration of polycyclic aromatic hydrocarbons (PNA) and polycyclic aromatic hydrocarbons (PAH). The feedstock of the present disclosure may have a cumulative concentration of partially hydrogenated PNA and partially hydrogenated PAH of about 20 wt% or more (e.g., about 50 wt% to about 90 wt%).

[0068] In some aspects, a suitable heavy feedstock may contain elemental nitrogen of about 50 wppm to about 10,000 wppm or more (i.e., the weight of nitrogen among various nitrogen-containing compounds in the feedstock). Additionally or alternatively, the heavy feedstock may contain elemental sulfur of about 100 wppm to about 20,000 wppm, preferably about 100 wppm to about 5,000 wppm. Sulfur will generally exist as organically bonded sulfur. Examples of such sulfur compounds include a class of heterocyclic sulfur compounds such as thiophene, tetrahydrothiophene, benzothiophene, and their higher homologues and analogs. Other organically bonded sulfur compounds include aliphatic, naphthenic, and aromatic mercaptans, sulfides, and disulfides and polysulfides.

[0069] Examples of suitable heavy feedstocks include, but are not limited to, main column bottom (MCB), steam cracker tar, heavy coker oil, steam cracker oil, vacuum residue, asphalt-removed residue or rock, hydroprocessed or hydrotreated forms of any of the foregoing, and combinations of any of the foregoing. A preferred heavy feedstock may be hydroprocessed MCB. Another preferred example of a heavy feedstock is hydroprocessed steam cracker tar. Steam cracker tar and subsequent hydroprocessing may be prepared / performed by any suitable method, including, for example, that disclosed in U.S. Patent No. 8,105,479, the entire contents of which are incorporated herein by reference.

[0070] heat treatment

[0071] In the process of the present disclosure, the heavy feedstock generally undergoes a heat treatment step to dealkylate and / or dehydrogenate the heavy feedstock and produce isotropic pitch and intermediate phase pitch. Advantageously, and unexpectedly, it has been found that the yield of intermediate phase pitch can be increased by using a higher temperature in a single heating step. More specifically, generally, the heat treatment can be performed at a temperature range of about 450°C to about 550°C, preferably about 480°C to about 510°C, for about 5 minutes to 8 hours, more preferably about 5 minutes to about 1 hour, most preferably about 5 minutes to about 30 minutes, for example, in the range of about 10 minutes to about 30 minutes. Typically, as the bromine value of the heavy feedstock decreases, the required severity of the heat treatment conditions increases. Generally, the heat treatment is performed under conditions sufficient to satisfy the relationship [X*Y] ≥ 31,000 seconds (e.g., ≥ 40,000 seconds, or ≥ 50,000 seconds, or ≥ 60,000 seconds, or ≥ 100,000 seconds, or ≥ 200,000 seconds, or ≥ 500,000 seconds), where X is the equivalent reaction time of heating and Y is the bromine value of the feedstock. For example, [X*Y] may be in the range of about 31,000 to about 1,000,000 seconds, e.g., about 40,000 seconds to about 700,000 seconds, or about 50,000 seconds to about 500,000 seconds, or about 50,000 seconds to about 100,000 seconds. For example, in an embodiment where the heavy feedstock has a bromine value of ≥10, the minimum ERT of the heat treatment step may be about 2,000 seconds or less, e.g., a minimum ERT of 500 seconds. In an embodiment where the heavy feedstock has a bromine value of less than 10, the minimum ERT of the heat treatment step may be greater than about 2,000 seconds, e.g., a minimum ERT of 10,000 seconds, or alternatively, a minimum ERT of 8,000 seconds.

[0072] Suitable pressures for the heat treatment step may be in the range of about 200 psig (1,380 kPa-g) to about 2,000 psig (13,800 kPa-g) when measured at the reactor inlet, e.g., about 400 psig (2,760 kPa-g) to about 1,800 psig (12,400 kPa-g), most preferably about 1,000 psig (6,894 kPa-g). The heat treatment may be carried out in any suitable vessel, e.g., a tank, piping, a tubular reactor, or a distillation column. Examples of suitable reactor configurations that may be used to carry out the heat treatment are described in U.S. Patent 9,222,027, the entire contents of which are incorporated herein by reference.

[0073] Intermediate pitch

[0074] The intermediate phase pitch produced from heat treatment (and optional subsequent separation step(s)) may be characterized by fine carbon residue (MCR) when measured according to ASTM D4530-15. Generally, the intermediate phase pitch of the present disclosure may have an MCR of 30 weight% or more (e.g., preferably about 50 weight% or more, more preferably about 60 weight% or more).

[0075] All characteristics of the softening point were measured according to ASTM D3104-14.

[0076] The intermediate phase pitch content was measured according to ASTM D4616-95 (2018).

[0077] carbon fiber

[0078] The intermediate pitch obtained from the process described herein can be used to form carbon fibers, as with the conventional melt spinning process. Melt spinning for the formation of carbon fibers is a known technique. For example, the book “Carbon-Carbon Materials and Composites” contains a chapter by DD Edie and RJ Diefendorf titled “Carbon Fiber Manufacturing”. Another example is the paper “Melt Spinning Pitch-Based Carbon Fibers”, Carbon, v.27(5), p 647, (1989)).

[0079] Process Overview

[0080] The process disclosed herein may be a continuous or semi-continuous process, but a continuous process is preferred. FIG. 1 is a non-limiting exemplary process of the present disclosure ( 100 Shows an overview of ). Heavy feedstock ( 102 ) is a vessel (preferably a tubular reactor) under conditions sufficient to satisfy the relationship [X*Y] ≥ 31,000 seconds ( 104 It undergoes a heat treatment step in ), where X is the equivalent reaction time for heating and Y is the feedstock ( 102 It is the bromine of ) (alternatively, the severity causes heating to produce an aligned liquid crystal intermediate phase). Container ( 104 The heat treatment step performed in ) is a heat-treated product or effluent containing intermediate phase pitch ( 106 It results in the formation of ). Optionally, the heat-treated product ( 106 ) is a separator( 108 Light hydrocarbons and vapor fractions ( 110 ) and intermediate pitch ( 112 Can form ). Optional steam injector ( 114 ) is courage ( 104 ) Previous feedstock( 102 ) into, container( 104 ) into, or in a container ( 104 ) subsequent leaks(106 Steam into ) 116 ) can be injected.

[0081] The following provides exemplary details regarding how the method of FIG. 4 may be implemented. A heavy hydrocarbon feed, e.g., MCB, may be fed into a tubular reactor to produce an intermediate phase precursor by operating at a pressure of 500 to 1,500 psig and a sufficiently high severity, e.g., > 1,000 equivalent seconds, preferably > 2,000 equivalent seconds. The temperature of the tubular reactor may be in the range of 450°C to 600°C, or more preferably 450°C to 520°C. The formed intermediate phase precursor may be maintained in slurry form in the tubular reactor to prevent reactor clogging. This may be accomplished by increasing the liquid line velocity in the tubular reactor, e.g., > 1 ft / sec, or preferably > 4 ft / sec. Optionally, the line velocity may be increased by injecting steam around the reactor tubes or at the outlet of the reactor tubes. The effluent may be sent to a separator, for example, a cyclone, operating at ambient pressure up to 50 psig to separate light hydrocarbons (and vapor) from the intermediate phase. The intermediate phase yield may range from 10 to 60%, preferably 13 to 50%, depending on the severity (higher severity, higher intermediate phase yield). The light hydrocarbons and vapor may be further separated by conventional distillation to recover the light hydrocarbons. The light hydrocarbons may optionally be recirculated to the inlet of a tubular reactor.

[0082] U.S. Patent 4,518,483 claimed to first extract the asphaltene fraction (heptane-insoluble) from a heavy hydrocarbon feedstock (such as MCB) and then convert the asphaltene into an intermediate phase in a batch-mode heat soaking unit. The intermediate phase was then concentrated by removing light through vacuum distillation or steam stripping. Given the relatively high softening point of asphaltene compared to MCB, it would be very difficult to transport and process it as a feedstock. In contrast, the continuous process of current technological advancements is designed to convert the heavy feedstock whole. Additionally, it generates the intermediate phase without the aid of stripping to concentrate it. The severity conditions differ from those of U.S. Patent 4,518,483, and instead, a cyclone can be used to separate the intermediate phase by gravity.

[0083] The following examples illustrate the invention. It should be understood that numerous modifications and variations are possible, and within the scope of the appended claims, the invention may be practiced differently from as specifically described herein.

[0084] Examples

[0085] Example 1: High-severity thermal conversion of heavy hydrocarbon feedstock

[0086] Main Column Bottom (MCB) from the refinery was used to produce an intermediate phase through a single thermal reaction (i.e., only a single heating step was applied to the MCB feedstock to produce the intermediate phase). The MCB feedstock used as an example has approximately 6% in the 566°C+ fraction (T94.5 at 567°C). Table 1 shows the severity conditions for three intermediate phase pitch production processes and their corresponding Equivalent Reaction Time (ERT). Equivalent Reaction Time (ERT) is used to quantify severity, with higher numbers indicating greater severity. ERT refers to the relative residence time under specified process conditions in relation to typical bisbreaker conditions at 468°C with an activation energy of 54 kcal / mol. Bisbreakers typically operate at 300 to 1,000 ERT. The intermediate phase production process was carried out in an autoclave where the feedstock was heat-treated under a high-pressure, inert environment. MCB undergoes thermal dealkylation and dehydrogenation to remove light, while simultaneously forming a condensed aromatic ring structure through polymerization. The product can be separated into two phases at elevated temperatures, with one part of the product being the total liquid product (TLP) and the other remaining as a solid. The TLP typically has a softening point below 100°C, while the solid has a softening point above 250°C. As the severity of the MCB conversion increases, the yield of the solid increases, while the yield of the TLP decreases, as shown in Table 1. At 460°C, the solid product exhibits intermediate phase characteristics with an intermediate phase content exceeding 80%, as shown in Figure 2. The H content is 4.81 wt%, which falls within the typical H range for the intermediate phase, which is 4.5 to 5 wt%. Similarly, the solid recovered at 470°C and 480°C exhibits optical characteristics of an intermediate phase under a microscope, and the yield of the solid can reach 46% at 480°C with an intermediate phase content of 75 to 85%.

[0087] The data in Table 1 shows that the intermediate phase yield can be in the range of 10 to 50 wt%, or preferably 13 to 46 wt%, greater than 1 wt%, greater than 13 wt%, or greater than 22 wt%. Although the data in Table 1 was generated in an autoclave in batch mode, the kinetics demonstrate that current technological advancements will produce a similar amount of intermediate phase under the same residence time in a continuous process.

[0088] [Table 1] Process conditions and ERT for the production of selected isotropic pitch

[0089]

[0090] Example 2: Low-severity thermal conversion of heavy hydrocarbon feedstock

[0091] The feedstock used in this example is the same as the feedstock in Example 1. The MCB was heat-treated at 440°C for 1 hour under 1,000 psi of N2. The corresponding ERT was approximately 850, indicating typical non-breaking conditions. Due to the low severity, no intermediate phase-like material was recovered, and as shown in Table 1, Run No. 4, the TLP yield reached 81.5%, with the remainder remaining as gas and light distillate. A comparison of Example 1 and Example 2 suggests that temperature is a significant result-effective variable for improving intermediate phase yield through one-stage thermal conversion, which embodies current technological advancements.

[0092] Example 3: Cost-effective and continuous one-stage thermal process for intermediate product production

[0093] Current commercial practices produce intermediate phases from isopitch in batch modes involving long residence times, medium to high temperatures, and potentially under vacuum. Batch processes can lead to serious contamination issues caused by excessive coking. Handling the intermediate phase in this process is labor-intensive because it must be sampled at elevated temperatures before solidifying in the reactor vessel. Collectively, commercial batch processes result in high production costs for the intermediate phase. In contrast, the one-stage thermal process of current technological advancements, which utilizes continuous flow tubular reactors and separators, produces the intermediate phase directly from MCB instead of isopitch, the intermediate product of MCB. Tubular reactors can operate at higher temperatures (>400 psig) but match the run severity as shown in Table 1, while mitigating coking with shorter residence times. For example, a continuous tubular reactor operating at 500°C with a residence time of 15 minutes corresponds to an equivalent superseverity of 4,000, which is similar to Run 2 in Table 1. Steam co-feeding to tubular reactors can further mitigate coke formation. Cyclones can separate the intermediate phase from light hydrocarbons and steam through gravity separation. This continuous configuration can produce the intermediate phase through cost-effective options and substantially reduce costs.

[0094] All documents described herein are incorporated herein by reference, including any prior documents and / or test procedures, to the extent that they do not conform to this document. As is evident from the foregoing general description and specific embodiments, the forms of this disclosure have been illustrated and described, but various modifications may be made without departing from the spirit and scope of this disclosure. Accordingly, this disclosure is not intended to be limited by this. Likewise, for the purposes of U.S. law, the term “comprising” is considered synonymous with the term “including.” Likewise, whenever a component, element, or group of elements comes before the transition phrase “comprising,” it is understood that the same group of components or elements is being considered where the transition phrases “essentially composed of,” “composed of,” “selected from a group composed of,” or “is” have preceded the reference to the component, element, or elements, and vice versa.

Claims

Claim 1 A method for producing intermediate phase pitch, comprising the steps of: providing a feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃); heating the feedstock at a temperature of at least 450℃ to produce a heat-treated product comprising intermediate phase pitch, wherein the heating is performed under reaction conditions sufficient to have an equivalent reaction time of at least 1,000 seconds; and recovering the intermediate phase pitch. Claim 2 A method for manufacturing intermediate phase pitch according to claim 1, wherein the temperature is less than 600℃. Claim 3 A method for producing intermediate-phase pitch according to claim 1, wherein the feedstock has a hydrogen content of 5.5 to 10 weight%. Claim 4 A method for producing intermediate phase pitch according to claim 1, wherein heating is the only heating step applied to the feedstock to produce intermediate phase pitch. Claim 5 A method for producing intermediate pitch according to claim 1, further comprising the step of injecting steam, wherein the steam is injected into a reactor, into a feedstock when the feedstock is supplied to the reactor, or into a heat-treated product including an intermediate pitch product from a reactor where heating occurs. Claim 6 A method for manufacturing intermediate pitch according to claim 1, wherein the yield of the intermediate pitch is greater than 1 weight%. Claim 7 A method for producing intermediate phase pitch according to claim 1, wherein the reaction conditions include an inert atmosphere, a temperature in the range of 450°C to 520°C, and a pressure in the range of 500 to 1,500 psig. Claim 8 A method for producing intermediate phase pitch according to claim 1, wherein X is the equivalent reaction time (ERT) of heating and Y is the bromine value of the feedstock as measured according to ASTM D1159, and the heating is performed under reaction conditions sufficient to satisfy the relationship [X*Y] ≥ 31,000 seconds. Claim 9 A method for manufacturing an intermediate phase pitch according to claim 1, further comprising controlling the temperature of the heating step so that the equivalent reaction time exceeds 1,000 seconds. Claim 10 A method for producing intermediate pitch according to claim 1, wherein the feedstock comprises a fraction having a boiling point of 1,050℉ (566℃) or higher in the range of 1% to 40% by weight based on the weight of the feedstock. Claim 11 A method for producing intermediate pitch according to claim 1, wherein the feedstock comprises at least one selected from the group consisting of main column bottom (MCB), hydrogenated MCB, steam cracker tar, hydrogenated steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum residue, asphalt-removed residue or rock, and mixtures or combinations thereof. Claim 12 A method for manufacturing intermediate phase pitch according to claim 1, wherein the step of recovering intermediate phase pitch includes separating intermediate phase pitch from light hydrocarbons. Claim 13 A method for manufacturing an intermediate phase pitch according to claim 1, wherein heating is performed in a reactor and the liquid linear velocity in the reactor is further controlled so that the intermediate phase precursor becomes a slurry. Claim 14 A system comprising: a reactor configured to receive a feedstock having T5 ≥ 400℉ (204℃) and T95 ≤ 1,400℉ (760℃) and to heat the feedstock at a temperature of at least 450℃ to produce a heat-treated product containing intermediate phase pitch, wherein the reactor is configured to heat the feedstock under reaction conditions sufficient to have an equivalent reaction time of at least 1,000 seconds; and a separation device fluidly connected to the reactor, wherein the separation device is configured to separate the intermediate phase pitch from the effluent received from the reactor. Claim 15 A system according to paragraph 14, further comprising a steam injector configured to inject steam into a reactor, into an effluent, and / or into a feedstock.

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