Thermal Conversion of Heavy Hydrocarbons into Mesophase Pitch

Abstract

1. A process for producing mesophase pitch, the process comprising the steps of: providing a feedstock having a T5≧400° F. (204° C.) and a T95≦1,400° F. (760° C.); heating the feedstock at a temperature of at least 450° C. to produce a heat-treated product comprising mesophase pitch, the heating being conducted under reaction conditions sufficient to have an equivalent reaction time of 1,000 seconds or greater; and recovering the mesophase pitch.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 172,340, filed on April 8, 2021, the disclosure of which is incorporated herein by reference in its entirety. Related Applications This disclosure is technically related to U.S. Provisional Application No. 63 / 138,051, filed on January 15, 2021, the entire content of which is incorporated herein by reference. Field This disclosure relates to the production of mesophase pitch, which is normally used for the production of carbon fibers.

Background Art

[0002] Background Isotropic pitch and mesophase pitch are carbon - containing raw materials that can be formed from residues produced during the processing of coal or petroleum feedstocks or by other methods such as acid - catalyzed condensation of small aromatic species. For some grades of carbon fibers, isotropic pitch can be used as the starting material. However, carbon fibers produced from isotropic pitch generally exhibit 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. Conventionally, the mesophase pitch can be produced by continuous isopitch separation using a wiped film evaporator after the thermal conversion of heavy aromatic hydrocarbons to isotropic pitch at medium to high pressure (>400 °C and >300 psi). The isotropic pitch is typically converted to the mesophase at >420 °C with a long residence time, e.g., >6 hours, in a batch mode under vacuum. The batch process is difficult to scale up due to temperature inhomogeneity in large autoclaves and a high tendency for coke formation. The current state of the art is typically limited to about 100 gal size. The inefficient batch process results in high production costs for the mesophase. The purpose of isopitch formation in the mesophase production process is to generate and concentrate the possible carbonaceous species of the mesophase precursor, i.e., the micro carbon residue (MCR). The autoclave process for mesophase production typically proceeds at temperatures above 425 °C with a long residence time, a low hydrocarbon partial pressure, and often in a vacuum. As a result, the production cost of the mesophase is very high, inevitably leading to expensive pitch-based carbon fibers. Despite the particularly high performance of pitch-based carbon fibers with respect to steel, pitch-based carbon fibers are limited to niche applications such as artificial satellites, sports goods, rocket engine nozzles, etc., which is mainly due to the high cost of mesophase production.

[0003] U.S. Patent No. 4,208,267 describes a method for forming mesophase pitch. An isotropic pitch sample is solvent-extracted. This extract is then subjected to a high temperature in the range of 230 °C to about 400 °C to form mesophase pitch. U.S. Patent No. 5,032,250 describes a process for isolating mesophase pitch. An isotropic pitch containing a mesogen is mixed with a solvent and subjected to dense phase or supercritical conditions to phase-separate the mesogen. U.S. Patent No. 5,259,947 describes a method for forming a solvated mesophase, including: (1) combining a carbonaceous aromatic isotropic pitch with a solvent; (2) applying sufficient stirring and sufficient heating to form suspension liquid solvated mesophase droplets in the insoluble substances in the combination; and (3) recovering the insoluble substances as solid or fluid solvated mesophase. U.S. Patent Publication No. 2019 / 0078023 describes the upgrading of crude oil and petroleum residues for the production of mesophase pitch and additional petrochemical products in an integrated process. Other potentially interesting references include U.S. Patent No. 4,518,483, U.S. Patent No. 9,222,027, U.S. Patent Publication No. 2019 / 0382665, and U.S. Patent Publication No. 2020 / 0181497.

Brief Description of the Drawings

[0004]

Figure 1

Figure 2

Figure 3

Summary of the Invention

[0005] Summary A process for producing mesophase pitch, including: preparing a raw material having T5≥400°F (204°C) and T95≤1,400°F (760°C); heating the raw material at a temperature of at least 450°C to produce a heat-treated product containing mesophase pitch, wherein the heating is carried out under reaction conditions sufficient to have an equivalent reaction time of 1,000 hours or more; and recovering the mesophase pitch. In this process, the temperature is less than 600°C. In this process, the raw material can have a hydrogen content of 5.5 - 10 wt%. In this process, the heating is only the heating step applied to the raw material to generate mesophase pitch. This process can further include a step of injecting steam into the reactor where heating is being carried out. This process can further include a step of injecting steam into the raw material when the raw material is supplied to the reactor. This process can further include a step of injecting steam into the heat - treated product including the mesophase pitch output from the reactor where heating is being carried out. In this process, the yield of mesophase pitch can be more than 1 wt%. In this process, the yield of mesophase pitch can be in the range of 10 wt% - 50 wt%. In this process, the yield of mesophase pitch can be in the range of 10 wt% - 60 wt%. In this process, the reaction conditions can include an inert atmosphere, a temperature in the range of 450°C - 520°C, and a pressure in the range of 500 - 1,500 psig.

[0006] In this process, X is the equivalent reaction time (ERT) of heating, Y is the bromine number of the raw material measured in accordance with ASTM D1159, and the heating is carried out under conditions sufficient to satisfy the relationship [X * Y] ≥ 31,000 seconds. This process can further include a step of controlling the temperature of the heating step to make the equivalent reaction time longer than 1,000 seconds. This process can include a raw material containing a fraction having a boiling point of ≥ 1,050°F (566°C) ranging from about 1 wt% to about 40 wt% based on the mass of the raw material. In this process, the feedstock can include at least one member selected from the group consisting of main column bottoms (MCB), hydroprocessed MCB, steam cracker tar, hydrotreated steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum resid, deasphalted bottoms or rock, and mixtures or combinations thereof. In this process, the step of recovering mesophase pitch can include the step of separating mesophase pitch from light hydrocarbons. In this process, heating can be carried out in a reactor, and the process further includes the step of controlling the liquid linear velocity in the reactor to form the mesophase precursor in slurry form. In this process, the control step can include the injection of steam.

[0007] A reactor configured to receive a feedstock having T5 ≧ 400°F (204°C) and T95 ≦ 1,400°F (760°C) and heat the feedstock at a temperature of at least 450°C to produce a heat-treated product containing mesophase pitch, the reactor being configured to heat the feedstock under reaction conditions sufficient to have an equivalent reaction time of 1,000 seconds or more, and a separation device in fluid communication with the reactor, the separation device being configured to separate mesophase pitch from the effluent received from the reactor. The system can further include a steam injector configured to inject steam into the reactor, the effluent, and / or the feedstock. In this system, the separation device can be a cyclone separator. In this system, the separation device can be a deasphalter.

DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION Unexpectedly, it has been found that mesophase pitch can be produced from slurry oil in a single thermal step. This unexpected result opens up the possibility of a continuous one-step thermal process to mesophase pitch, as shown in Figure 1. Embodiments of the technical advancement of the present invention can utilize a single thermal step using a continuous flow tubular reactor at operating temperatures above 400 psig (measured at the reactor inlet). Compared to conventional processes, this tubular reactor operates at higher temperatures but with shorter residence times to reduce coking and operates in harmony with the severity of continuous operation. For example, a continuous tubular reactor operating at 500 °C with a residence time of 15 minutes corresponds to 4,000 equivalent sec severity. Simultaneous supply of steam to the tubular reactor can be utilized either before the input of the reactor or after the output of the reactor. A separation device, such as a cyclone by gravity separation or a DAU (deasphalting unit) by solubility, can separate the mesophase from light hydrocarbons and steam.

[0009] Mesophase can be made by a one-step thermal process different from the two-step process described in the background section. A feedstock having a relatively high H content (i.e., 5.5 wt% - 10 wt%, preferably 7 - 8 wt%) relative to isopitch (i.e., 5 - 6 wt%), such as main column bottoms (MCB), can be directly converted to mesophase at high temperature. Exemplary embodiments of the technical advancement of the present invention include: (1) a step of heat-treating the feedstock under severity conditions higher than typical visbreakering conditions; (2) the pressure is constant (or substantially constant with fluctuations not exceeding + / - 10% over the residence time) during the reaction that induces stripping of the light fraction from the reaction vessel; (3) a long residence time allows for sufficient aromatic polymerization to form a regular mesophase that is anisotropic in form and can be evaluated by polarized light microscopy due to its inherent birefringence; and (4) recovering the mesophase by separating the mesophase from light hydrocarbons, for example, by simply decanting the liquid product in the case of a cyclone or a batch process. The various embodiments described herein provide a process for manufacturing mesophase pitch from heavy feedstocks having T5 ≥ 400°F (204°C) and T95 ≤ 1,400°F (760°C). However, with the technological advancement of the present invention, other feedstocks from MCB can be used. Generally, a single heat treatment of the heavy feedstock is carried out at a temperature in the range of about 450°C to about 520°C and a residence time of 5 minutes to 8 hours, more preferably about 3 minutes to about 6 hours, even more preferably 5 minutes to 1 hour, for example about 10 minutes to about 60 minutes (or 1 hour), and most preferably 5 minutes to 30 minutes.

[0010] All numerical values within the detailed description and claims of this application are indicated values modified by "about (about or approximately)", taking into account experimental errors and variations that those skilled in the art would expect. Unless otherwise indicated, room temperature is about 23°C. As used herein, "wt%" means mass percentage, "vol%" means volume percentage, "mol%" means mole percentage, "ppm" means one part per million, and "ppm wt" and "wppm" are used interchangeably to mean one part per million on a mass basis. All "ppm" used herein are mass ppm unless otherwise specified. All concentrations in this specification are expressed based on the total amount of the composition in question. All ranges described in this specification should include both endpoints as two specific embodiments unless otherwise specified or indicated to the contrary.

[0011] Definitions For the purposes of this specification and the appended claims, the following terms are defined. As used herein, the term "equivalent reaction time" or "equivalent residence time" (ERT) refers to the severity of an operation expressed as the number of seconds of residence time for a reaction having an activation energy of 54 kcal / mol in a reactor operating at 468°C. The ERT of an operation is calculated as follows.

[0012]

Number

[0013] As used herein, the term "pitch" refers to a viscoelastic carbonaceous residue obtained from the distillation of petroleum, coal tar, or other organic substrates. Unless otherwise defined herein, the term "pitch" refers to petroleum pitch (i.e., pitch obtained from the distillation of petroleum). As used herein, the term "isotropic pitch" refers to a pitch containing molecules that are not aligned in an optically regular liquid crystal state. As used herein, the term "main column bottoms (MCB)" refers to the bottom fraction from a fluid catalytic cracking process. More specifically, MCB refers to the fraction of the products of a catalytic cracking process that boils in the range of about 200 °C to 650 °C. However, the boiling point range can vary depending on the operating conditions. As used herein, the term "mesophase pitch" or "mesophase" refers to a pitch that is a structurally regular optically anisotropic liquid crystal. The mesophase structure can be described and characterized by various techniques such as optical birefringence, light scattering, or other scattering techniques.

[0014] Test Methods Mesophase Pitch Content by Optical Microscopy Unless otherwise specified in this specification, the mesophase pitch content of a sample is determined by optical microscopy according to the following procedure. A digital image of the sample is produced using an optical microscope. Next, in the light intensity region corresponding to the mesophase pitch due to its high refractive index, a histogram of the total number of pixels of the digital image is created by color intensity. The image is divided into a mesophase pitch area and a non-mesophase pitch area by threshold processing in an area having an intensity less than a specific threshold corresponding to the mesophase pitch. Next, after subtracting the non-mesophase pitch area of the image, an estimated value of the mesophase pitch content of the sample in area % is obtained by dividing the total amount of the mesophase pitch area of the image by the total area of the image (the result can then be extrapolated to correspond to an estimated value in vol%). The following further details specific aspects of the present invention. The following description relates to specific aspects, but these are merely illustrative and those skilled in the art will understand that the present invention can be implemented in other ways. References to the "invention" may refer to one or more of the inventions defined by the claims, but not necessarily all. The use of headings is for convenience only and should not be construed as limiting the scope of the invention to specific aspects.

[0015] Heavy raw material In the process of the present disclosure, the heavy feedstock may be characterized by its boiling point range. One option for defining the boiling point range is to use the initial boiling point of the feed and / or the final boiling point of the feed. In some cases, another option that may provide a more representative description of the feed is to characterize the feed based on the amount of feed boiling at one or more temperatures. For example, the "T5" boiling point of the feed is defined as the temperature at which 5 wt% of the feed is boiling. Similarly, the "T95" boiling point is the temperature at which 95 wt% of the feed is boiling. The percentage of the feed boiling at a given temperature can be determined, for example, by the method specified in ASTM D2887 (or, if ASTM D2887 is not suitable for a particular fraction, by the method of ASTM D7169). Generally, the heavy feedstock may have a T95 of T5 ≧ 400°F (204°C) and ≦ 1,400°F (760°C). Examples of such heavy feedstocks include those having a 1,050°F+ (566°C+) fraction. In some embodiments, the 566°C+ fraction may correspond to 1 wt% or more of the heavy feedstock (i.e., T99 at 566°C or higher), or 2 wt% or more (T98 at 566°C or higher), or 10 wt% or more (T90 at 566°C or higher), or 15 wt% or more (T85 at 566°C or higher), or 30 wt% or more (T70 at 566°C or higher), or 40 wt% or more (T60 at 566°C or higher), for example, from about 1 wt% to about 40 wt% or from about 2 wt% to about 30 wt%.

[0016] The heavy feedstock of the present disclosure may be characterized by its reactivity as measured by its bromine number. The heavy feedstock of the present disclosure may have a bromine number of ≧ 3, or ≧ 5, or ≧ 10, or ≧ 30, or ≧ 40, for example, from about 3 to about 50, or from about 5 to about 40, or from about 10 to about 30, as measured in accordance with ASTM D1159. The heavy feedstock of the present disclosure may be characterized by its aromatic content. The heavy feedstock of the present disclosure may contain about 40 mol% or more, or about 50 mol% or more, or about 60 mol% or more, for example, up to about 75 mol% or perhaps even more aromatic carbon. The aromatic carbon content of the heavy feedstock can be determined in accordance with ASTM D5186. The heavy feedstock of the present disclosure may be characterized by an average carbon number. The heavy feedstock of the present disclosure may be composed of hydrocarbons having an average carbon number of about 33 to about 45 (for example, about 35 to about 40, or about 37 to about 42, or about 40 to about 45). The heavy feedstock of the present disclosure may be characterized by microcarbon residue (MCR) measured according to ASTM D4530-15. The heavy feedstock of the present disclosure may have an MCR of about 5 wt% or more (for example, about 5 wt% to about 45 wt%, or about 10 wt% to about 45 wt%). 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 wt% to about 11 wt%, for example about 6 wt% to about 10 wt%, or about 7 wt% to about 8 wt%. The heavy feedstock of the present disclosure may be characterized by the cumulative concentration of polynuclear aromatic hydrocarbons (PNA) and polycyclic aromatic hydrocarbons (PAH). The heavy feedstock of the present disclosure may have a cumulative concentration of partially hydrogenated PNA and partially hydrogenated PAH of about 20 wt% or more (for example, about 50 wt% to about 90 wt%).

[0017] In some embodiments, a suitable heavy feedstock may contain from about 50 wppm to about 10,000 wppm or more of elemental nitrogen (i.e., the mass of nitrogen in the various nitrogen-containing compounds in the feedstock). Additionally or alternatively, the heavy feedstock may contain from about 100 wppm to about 20,000 wppm of elemental sulfur, preferably from about 100 wppm to about 5,000 wppm of elemental sulfur. The sulfur will typically be present as organically bound sulfur. Examples of such sulfur compounds include classifications of heterocyclic sulfur compounds such as thiophene, tetrahydrothiophene, benzothiophene, etc. as well as their higher homologs and analogs. Other organically bound sulfur compounds include aliphatic, naphthenic, and aromatic mercaptans, sulfides, and disulfides and polysulfides. Examples of suitable heavy feedstocks include, but are not limited to, main column bottoms (MCB), steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum residue, deasphalted residue or rock, any hydroprocessed or hydrotreated form of any of the foregoing, and any combination of any of the foregoing. A preferred heavy feedstock can be hydroprocessed MCB. Another preferred example of a heavy feedstock is hydrotreated steam cracker tar. Steam cracker tar and subsequent hydrotreating can be produced / implemented by any suitable method, as disclosed in U.S. Patent No. 8,105,479, which is hereby incorporated by reference in its entirety.

[0018] Heat treatment In the process of the present disclosure, the heavy feedstock generally undergoes a heat treatment step to dealkylate and / or dehydrogenate the heavy feedstock to produce isotropic pitch and mesophase pitch. Advantageously and unexpectedly, it has been found that the yield of mesophase pitch can be increased by using a higher temperature in a single heating step. More specifically, generally, the heat treatment is carried out at a temperature in the range of about 450 °C to about 550 °C, preferably about 480 °C to about 510 °C, and a residence time in the range of 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 about 10 minutes to about 30 minutes. Typically, the required severity of the heat treatment conditions increases as the bromine number of the heavy feedstock decreases. Generally, the heat treatment is carried out under conditions sufficient to satisfy the relationship [X*Y]≧31,000 seconds (for example, ≧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 number of the feedstock). For example, [X*Y] may be in the range of about 31,000 to about 1,000,000 seconds, for example 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 embodiments where the heavy feedstock has a bromine number ≧10, the minimum ERT of the heat treatment step can be about 2,000 seconds or less, for example a minimum ERT of 500 seconds. In embodiments where the heavy feedstock has a bromine number <10, the minimum ERT of the heat treatment step can be greater than about 2,000 seconds, for example a minimum ERT of 10,000 seconds, or a minimum ERT of 8,000 seconds.

[0019] The appropriate pressure for the heat treatment step, measured at the reactor inlet, can range from about 200 psig (1,380 kPa-g) to about 2,000 psig (13,800 kPa-g), such as from about 400 psig (2,760 kPa-g) to about 1,800 psig (12,400 kPa-g), and most preferably about 1,000 psig (6,894 kPa-g). The heat treatment can be carried out in any vessel, such as a tank, pipe, tubular reactor, or distillation column. Examples of suitable reactor configurations that can be utilized to carry out the heat treatment are described in U.S. Patent No. 9,222,027, the entire contents of which are hereby incorporated by reference.

[0020] Mesophase pitch The mesophase pitch resulting from the heat treatment (and optional subsequent separation steps) can be characterized by the microresidual carbon content (MCR) measured in accordance with ASTM D4530-15. Generally, the mesophase pitch of the present disclosure can have an MCR of 30 wt% or more (e.g., preferably about 50 wt% or more, more preferably about 60 wt% or more). Any characterization of the softening point was evaluated in accordance with ASTM D3104-14. The mesophase pitch content was measured in accordance with ASTM D4616-95(2018).

[0021] Carbon fiber Using the mesophase pitch obtained from the process described herein, carbon fibers can be formed, for example, by utilizing a 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” includes a chapter by D.D. Edie and R.J. Diefendorf entitled “Carbon Fiber Manufacturing”. Another example is the paper “Melt Spinning Pitch-Based Carbon Fibers”, Carbon, v.27(5), p 647, (1989).

[0022] Overview of the process The processes disclosed herein may be continuous or semi - continuous processes, but are preferably continuous processes. Figure 1 shows an overview of a non - limiting process example 100 of the present disclosure. A heavy feedstock 102 is subjected to a heat treatment step within a vessel (preferably a tubular reactor) 104 under conditions sufficient to satisfy the relationship [X*Y]≧31,000 seconds (where X is the equivalent reaction time of heating and Y is the bromine number of the feedstock 102) (another possibility is that the severity is such that heating creates a regular liquid - crystal mesophase). The heat treatment step carried out within the vessel 104 results in the formation of a heat - treated product or effluent 106 that includes a mesophase pitch. Optionally, the heat - treated product 106 can undergo a separation step within a separation device 108 to form a light hydrocarbon and steam fraction 110 and a mesophase pitch 112. An optional steam injector 114 can inject steam 116 into the feedstock 102 in front of the vessel 104, or into the vessel 104, or into the effluent 106 after the vessel 104.

[0023] Examples of how to implement the method of FIG. 4 are provided below. A heavy hydrocarbon feed, such as MCB, can be fed to a tubular reactor operating at a pressure of 500 - 1,500 psig and a sufficiently high severity, such as > 1,000 equivalent seconds, preferably > 2,000 equivalent seconds, to produce a mesophase precursor. The temperature in the tubular reactor can be in the range of 450°C to 600°C, more preferably 450°C to 520°C. To prevent reactor plugging, the formed mesophase precursor can be maintained in slurry form within the tubular reactor. This can be accomplished by increasing the liquid linear velocity in the tubular reactor to, for example, > 1 ft / sec, preferably > 4 ft / sec. In some cases, steam can be injected around the reactor tube or at the reactor tube outlet to increase the linear velocity. The effluent can be sent to a separation device, such as a cyclone operating at atmospheric pressure to 50 psig, to separate light hydrocarbons (and steam) from the mesophase. The yield of the mesophase can be in the range of 10 - 60%, preferably 13 - 50% (the higher the severity, the higher the mesophase yield). The light hydrocarbons and steam can be further separated by conventional distillation to recover the light hydrocarbons. Optionally, the light hydrocarbons can be recycled to the inlet of the tubular reactor.

[0024] U.S. Patent 4,518,483 first claims the extraction of the asphaltene fraction (heptane-insoluble) from a heavy hydrocarbon feedstock (such as MCB), and then the conversion of the asphaltene to the mesophase in a batch-mode heat soaking unit. Subsequently, vacuum distillation or steam stripping is followed to remove light materials to concentrate the mesophase. Considering its relatively high softening point compared to MCB, it would be very difficult to transfer and process the asphaltene as a feed. In contrast, the continuous process of the technological advancement of the present invention is designed to convert the entire heavy feedstock. Further, the mesophase is generated without the aid of stripping to concentrate the mesophase. The severity conditions, unlike those of U.S. Patent 4,518,483, can instead use a cyclone to separate the mesophase by gravity. The following examples illustrate the present invention. It should be understood that numerical modifications and changes are possible and that the present invention may be practiced in ways other than those specifically described herein within the scope of the appended claims.

Example

[0025] Example Example 1: High-severity thermal conversion of heavy hydrocarbon feedstock A mesophase was produced via a single thermal reaction using the main column bottoms (MCB) obtained from the essential oil fraction (i.e., applying the only heating step to the MCB feedstock to generate the mesophase). The MCB feedstock used in this example is about 6% in the 566 °C+ fraction (T94.5 of 567 °C). Table 1 shows the severity conditions of three mesophase pitch preparation processes and their corresponding equivalent reaction times (ERT). The equivalent reaction time (ERT) is used to quantify the degree of severity, with higher numbers indicating a higher degree of severity. ERT refers to the relative residence time under the specified process conditions relative to typical bis-breaking conditions having an activation energy of 54 kcal / mol at 468 °C. Bis-breakers typically operate at 300 - 1,000 ERT. The mesophase formation process was carried out in an autoclave under high pressure with heat treatment of the feedstock in an inert environment. The MCB undergoes thermal dealkylation and dehydrogenation, polymerizing to form a condensed aromatic ring structure while removing light materials. This product can be separated into two phases at high temperature, with a portion of the product being the total liquid product (TLP) and the other portion remaining as a solid. The TLP typically has a softening point of less than 100 °C, and the solid has a softening point of greater than 250 °C. As shown in Table 1, as the severity of the MCB conversion increases, the yield of the solid increases while the yield of the TLP decreases. At 460 °C, as shown in Figure 2, the solid product exhibits the characteristics of a mesophase, with a mesophase content exceeding 80%. The H content is 4.81 wt%, which falls within the typical H range for mesophases that are 4.5 - 5 wt%. Similarly, the solids recovered at 470 °C and 480 °C also exhibit the optical characteristics of a mesophase under the microscope, and the yield of the solid can reach 46% at 480 °C, with a mesophase content of 75 - 85%. The data in Table 1 show that the yield of the mesophase is in the range of 10 - 50 wt%, preferably 13 - 46 wt%, and can be greater than 1 wt%, greater than 13 wt%, or greater than 22 wt%. The data in Table 1 were generated from a batch-mode autoclave, but the kinetics demonstrate that the technological advancement of the present invention produces a similar amount of mesophase under the same residence time in a continuous process.

[0026] Table 1. Process conditions and ERT for selected isotropic pitch generation [Table 1]

[0027] Example 2: Low-severity thermal conversion of heavy hydrocarbon feedstocks The feedstock used in this example is the same as that 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, which corresponds to typical visbreaking conditions. As shown in Experiment No. 4 of Table 1, due to the low severity, no mesophase-like material was recovered and remained as gas and light distillate, resulting in a TLP yield of 81.5%. The comparison between Example 1 and Example 2 suggests an important result that temperature is an effective variable for increasing the mesophase yield by one-step thermal conversion utilizing the technological advancement of the present invention.

[0028] Example 3: Cost-effective continuous one-step thermal process for mesophase production Current commercial practice manufactures mesophase from isopiitch in batch mode with long residence times, medium to high temperatures and possibly under vacuum. The batch process can result in significant fouling problems due to excessive coking. Handling of mesophase in this process is labor intensive as the mesophase needs to be harvested at high temperatures before it solidifies in the reaction vessel. In summary, the commercial batch process leads to high cost production of mesophase. In contrast, the one-step thermal process of the technological advance of the present invention that can use a continuous flow tubular reactor and separation device creates mesophase directly from MCB instead of isopiitch, an intermediate product of MCB. The tubular reactor operates at >400 psig, at high temperature but with short residence times, and can reduce coking while being compatible with the severity of the experiments as shown in Table 1. For example, a continuous tubular reactor operating at 500 °C with a residence time of 15 minutes is equivalent to a severity of 4,000 equivalent seconds similar to Experiment 2 in Table 1. Simultaneous supply of steam to the tubular reactor was able to further reduce coke formation. A cyclone can separate mesophase from light hydrocarbons and steam by gravitational separation. This continuous configuration enables a cost-effective option for manufacturing mesophase and substantially reduces costs.

[0029] All documents described herein are incorporated herein by reference to the extent that they do not conflict with this text, including any priority documents and / or test procedures. As is apparent from the foregoing general description and the specific embodiments, while the forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, the disclosure is not intended to be limited thereby. Similarly, the term "comprising" is considered synonymous with the term "including" for purposes of U.S. law. Similarly, whenever a transitional phrase "comprising" precedes a description of a composition, element, group of elements, there is a common understanding that the same composition or group of elements preceded by a transitional phrase "consisting essentially of", "consisting of", "selected from the group consisting of", or "being" is also contemplated, and vice versa. Another aspect of the present invention may be as follows. 〔1〕A manufacturing process of mesophase pitch, preparing a raw material having T5≥400°F (204°C) and T95≤1,400°F (760°C); heating the raw material at a temperature of at least 450°C to produce a heat-treated product containing mesophase pitch, wherein the heating is carried out under reaction conditions sufficient to have an equivalent reaction time of 1,000 seconds or more; recovering the mesophase pitch; The process includes the above steps. 〔2〕The process according to 〔1〕, wherein the temperature is less than 600°C. 〔3〕The process according to any one of 〔1〕 to 〔2〕, wherein the raw material has a hydrogen content of 5.5 to 10 wt%. 〔4〕The process according to any one of 〔1〕 to 〔3〕, wherein the heating is only the heating step applied to the raw material to produce the mesophase pitch. 〔5〕The process according to any one of 〔1〕 to 〔4〕, further including a step of injecting steam, wherein the steam is injected into the reactor, or into the raw material when the raw material is supplied to the reactor, or into the heat-treated product containing the mesophase pitch output from the reactor where the heating is carried out. 〔6〕The process according to any one of 〔1〕 to 〔5〕, wherein the yield of the mesophase pitch is more than 1 wt%, preferably 10 wt% to 50 wt% or 10 to 60%. 〔7〕The process according to any one of 〔1〕 to 〔6〕, 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. 〔8〕X is the equivalent reaction time (ERT) of the heating, Y is the bromine number of the raw material measured in accordance with ASTM D1159, and the heating is carried out under reaction conditions sufficient to satisfy the relationship [X*Y]≥31,000 seconds. 〔9〕The process according to any one of 〔1〕 to 〔8〕, further including a step of controlling the temperature of the heating step to make the equivalent reaction time longer than 1,000 seconds. 〔10〕The process according to any one of 〔1〕 to 〔9〕, wherein the raw material contains a fraction having a boiling point of ≥1,050°F (566°C) ranging from about 1 wt% to about 40 wt% based on the mass of the raw material. 〔11〕The process according to any one of 〔1〕 to 〔10〕 above, wherein the raw material comprises at least one member selected from the group consisting of main column bottoms (MCB), hydroprocessed MCB, steam cracker tar, hydrogenated steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum residue, deasphalted residue or rock, and mixtures or combinations thereof. 〔12〕The process according to any one of 〔1〕 to 〔11〕 above, wherein the step of recovering the mesophase pitch comprises separating the mesophase pitch from light hydrocarbons. 〔13〕The process according to any one of 〔1〕 to 〔12〕 above, wherein the heating is carried out in a reactor, and the process further comprises controlling the liquid linear velocity in the reactor to form the mesophase precursor in a slurry form. 〔14〕A reactor configured to receive a raw material having T5 ≧ 400°F (204°C) and T95 ≦ 1,400°F (760°C) and to heat the raw material at a temperature of at least 450°C to produce a heat-treated product containing mesophase pitch, the reactor being configured to heat the raw material under reaction conditions sufficient to have an equivalent reaction time of 1,000 seconds or more, and A separation device in fluid communication with the reactor, the separation device being configured to separate mesophase pitch from the effluent received from the reactor, preferably the separation device is a cyclone separator or a deasphalter, and the separation device A system comprising. 〔15〕The system according to 〔14〕 above, further comprising a steam injector configured to inject steam into the reactor, into the effluent, and / or into the raw material.

Claims

1. A manufacturing process for mesophase pitch, comprising the step of preparing a raw material having T5≥400°F (204°C) and T95≤1,400°F (760°C), and containing a fraction having a boiling point of ≥1,050°F (566°C) of 1 wt% or more based on the mass of the raw material; the step of heating the raw material at a temperature of at least 450°C to produce a heat treatment product containing mesophase pitch, wherein the heating is carried out under reaction conditions sufficient to have an equivalent reaction time (ERT) of 1,000 seconds or more, and the ERT is calculated as follows, where W is the residence time in seconds; e is 2.71828; Ea is 225,936 J / mol; R is 8.3145 J·mol-1·K-1; Trxn is the temperature represented in Kelvin; the step of recovering the mesophase pitch; and the process comprising the above.

2. The process according to claim 1, wherein the temperature is less than 600°C and the raw material has a hydrogen content of 5.5 - 10 wt%.

3. The heating is only the heating step applied to the raw material to produce the mesophase pitch, the yield of the mesophase pitch is more than 1 wt%, and the reaction conditions include an inert atmosphere, a temperature in the range of 450°C - 520°C, and a pressure in the range of 500 - 1,500 psig (3,447 - 10,342 kPa-g). The process according to claim 1.

4. Further comprising the step of injecting steam, wherein the steam is injected into the reactor, or into the raw material when the raw material is supplied to the reactor, or into the heat treatment product containing the mesophase pitch output from the reactor where the heating is being carried out. The process according to claim 1.

5. X is the equivalent reaction time (ERT) of the heating, Y is the bromine number of the raw material measured in accordance with ASTM D1159, and the heating is carried out under reaction conditions sufficient to satisfy the relationship [X * Y] ≥ 31,000 seconds, and the process further includes a step of controlling the temperature of the heating step to make the equivalent reaction time longer than 1,000 seconds, the process according to claim 1.

6. The process according to claim 1, wherein the raw material includes a fraction having a boiling point of ≧ 1,050°F (566°C) ranging from 1 wt% to 40 wt% based on the mass of the raw material.

7. The process according to claim 1, wherein the raw material includes at least one member selected from the group consisting of main column bottoms (MCB), hydrotreated MCB, steam cracker tar, hydrotreated steam cracker tar, heavy coker gas oil, steam cracker gas oil, vacuum residue, deasphalted residue or rock, and mixtures or combinations thereof.

8. The step of recovering the mesophase pitch includes a step of separating the mesophase pitch from light hydrocarbons, the heating is carried out in a reactor, and the process further includes a step of controlling the liquid linear velocity in the reactor to make the mesophase precursor in a slurry form, the process according to claim 1.

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