Process for the production of phenol

Abstract

A method for separating phenol may include: separating a first portion of acetone from a product stream in an evaporator unit, wherein the first portion of acetone comprises recycled acetone and bypass acetone; recycling the recycled acetone; discharging a bottom fraction from the evaporator unit; neutralizing the bottom fraction to form a distillation feed stream, which is directed to a distillation column; separating the distillation feed stream into a bottom stream and a top stream, the bottom stream comprising a crude phenol fraction; passing the top stream through a condenser to produce a distillate as a crude acetone fraction, and wherein the reflux ratio of the distillation column is less than or equal to 0.40, wherein the reflux ratio is the ratio of the weight of the reflux to the weight of the distillate; and guiding bypass acetone around the distillation column.

Description

[0001] Related applications

[0002] This application is an international application claiming priority to Russian patent application 2020135296, filed on October 27, 2020, the entire contents of which are incorporated herein by reference. Background Technology

[0003] Phenol produced on an industrial scale via acid-catalyzed cracking / decomposition of cumene hydroperoxide (CHP) can be purified by a series of distillations, in which progressively heavier components of the cracking mixture are separated as bottom streams. The decomposition products are separated after neutralization into products of phenol and acetone, byproducts, and unreacted cumene (CUM) for recycling. The neutralized cumene hydroperoxide cracking products can be separated by a column (also known as a distillation column) into a crude acetone fraction (top stream) and a crude phenol fraction (bottom stream). Impurities such as hydroxyacetone (HA) and α-methylstyrene (AMS) can be removed in the top stream, with some AMS recovered in the bottom stream.

[0004] Many phenol production facilities overload their first column (e.g., a distillation column), separating the neutralized cumene hydroperoxide cracking product into a crude acetone fraction (top stream) and a crude phenol fraction (bottom stream) in an attempt to increase column output. However, this practice can disrupt the mass balance and efficiency of the first column, resulting in an increase in unwanted hydroxyacetone and α-methylstyrene impurities in the crude phenol product stream. Several (e.g., three) additional columns may follow the first column. The produced phenol can be used to produce bisphenol A (BPA). Ideally, BPA production uses reactants with very low impurities. HA is known to have an adverse effect on the color and quality of BPA, potentially leading to poor polycarbonate (PC) color.

[0005] Therefore, overloading the distillation column can significantly reduce the quality and commercial value of the final phenol product. Even after production, impurities can continue to form in the phenol product. For example, the impurity 2-methylbenzofuran (2-MBF) is formed via the interaction of hydroxyacetone and phenol and is extremely difficult to remove.

[0006] Hydroxyacetone removal methods can include both physical (e.g., distillation) and chemical (e.g., the addition of chemical reagents) methods, both of which are expensive and increase the complexity of the phenol purification system. Therefore, these removal methods should be avoided if possible. The quality of hydroxyacetone removal can also depend on many factors, such as the composition of the crude phenol, process parameters, and the efficiency of the equipment or mass transfer device.

[0007] U.S. Patent No. 3,405,038 describes a method for removing hydroxyacetone from a neutralized cumene hydroperoxide cracking mixture using azeotropic distillation. Hydroxyacetone forms a minimal azeotrope with cumene. According to the method in U.S. Patent No. 3,405,038, efficient removal of hydroxyacetone from a crude phenol stream requires a feed ratio of at least 0.28 parts by weight of cumene to one part by weight of phenol. Additional cumene is required if the initial feed quality is relatively low. Furthermore, the temperature is maintained at 110°C above the feed point to the boiling point of cumene. In examples, the hydroxyacetone content in the understream varies from 30 to 65 ppm. However, these levels of hydroxyacetone are generally unacceptable for modern phenol production. Moreover, this method requires the continuous recycling of large quantities of cumene; this is costly in terms of capital and utility usage.

[0008] U.S. Patent No. 4,251,325 discloses that phenol containing less than 30 ppm hydroxyacetone can be produced from a crude phenol fraction after separation of a neutralized hydroperoxide cumene cracking mixture in a distillation column, wherein acetone and water are separated from the phenol fraction. In a further subsequent distillation column, the distillation is maintained at a maximum of 22.0 wt% of a combination of cumene and / or α-methylstyrene. The feed containing AMS and / or cumene is fed to the middle point in the subsequent distillation column; the top fraction containing cumene and α-methylstyrene, as well as most of the hydroxyacetone present in the feed, is removed as a top product. The phenol fraction containing less than 30 ppm hydroxyacetone is removed from the bottom stream. By adjusting the temperature and pressure, the column is controlled such that the highest 15 to 70% of the trays in the stripping section constitute a composition of 55 to 80 wt% cumene and / or α-methylstyrene, and the lowest 10 to 50% of the trays in the stripping section constitute a composition of more than 50 wt% phenol. This method represents an improvement over U.S. Patent No. 3,405,038; however, it still has many drawbacks. For example, implementing this method requires the use of additional towers with very high reflux ratios (e.g., 17 to 29), which equates to high capital and high operating costs.

[0009] In Russian Patent No. 2,323,202, after separating the neutralized hydroperoxide cumene cracking products into crude acetone and crude phenol fractions, the removal of hydroxyacetone from the recovered crude phenol fraction using azeotropic extractive distillation with a separating agent is described. The separating agent includes hydrocarbons (cumene and / or α-methylstyrene) as one component and water as a second component. RU Patent No. 2,323,202 involves feeding one or more separating agents into a column along with crude phenol, maintaining a hydrocarbon-to-water mass ratio equal to or higher than the hydrocarbon-to-water mass ratio in the corresponding azeotropic mixture. The hydroxyacetone separating agent is removed along with the distillate; and the organic phase of the distillate is used for reflux. Significant disadvantages of this method include a high reflux ratio varying from 2 to 3 and correspondingly high energy consumption, and an increased phenol content of up to 3% in the aqueous phase. Removing this phenol loads the dephenolization zone of the equipment. Furthermore, this method is not very efficient.

[0010] Other methods for reducing hydroxyacetone are, to varying degrees, capital-intensive and have increased operating costs. Summary of the Invention

[0011] In various embodiments of this disclosure, systems and methods for producing phenol, as well as systems and methods for separating phenol from phenol product streams, are disclosed.

[0012] There is a need for a method for phenol production that avoids overloading distillation columns (e.g., crude acetone distillation columns), thereby maintaining column efficiency and significantly reducing impurity levels in the phenol product.

[0013] A method for separating phenol may include: separating a first portion of acetone from a product stream in an evaporator unit, wherein the first portion of acetone comprises recycled acetone and bypass acetone; recycling the recycled acetone; discharging a bottom fraction from the evaporator unit; neutralizing the bottom fraction to form a distillation feed stream, directing the distillation feed stream to a distillation column; separating the distillation feed stream into a bottom stream and a top stream, the bottom stream comprising a crude phenol fraction; passing the top stream through a condenser to produce a distillate as a crude acetone fraction, and wherein the reflux ratio of the distillation column is less than or equal to 0.40, wherein the reflux ratio is the ratio of the weight of the reflux to the weight of the distillate; and directing bypass acetone around the distillation column.

[0014] The above and other features are illustrated by examples with accompanying drawings and detailed descriptions.

[0015] Any combination or arrangement of implementations is contemplated. Other advantageous features, functions, and applications of the systems and methods disclosed in this disclosure will become apparent from the following description, especially when read in conjunction with the accompanying drawings. All references listed in this disclosure are incorporated herein by reference in their entirety. Attached Figure Description

[0016] The following is a brief description of the accompanying drawings, in which similar elements are similarly numbered and are presented for the purpose of illustrating exemplary embodiments disclosed herein, and not for the purpose of limiting them.

[0017] Exemplary embodiments of this disclosure are further described with reference to the accompanying drawings. It should be noted that the various steps, features, and combinations of steps / features described below and shown in the drawings may be arranged and configured differently to obtain embodiments still within the scope of this disclosure. For the convenience of those skilled in the art in making and using the disclosed systems and methods, reference is made to the accompanying drawings, in which:

[0018] Figure 1 This is a schematic diagram illustrating the system configuration used in methods for producing phenol and / or for separating phenol from product streams.

[0019] Figure 2 It is a graph representing the temperature profile data of the columns used in the methods for producing phenol and / or for separating phenol from the product stream; Figure 2 The determined temperature profiles for the removal of hydroxyacetone (lines 1 to 3) and for the removal of hydroxyacetone and α-methylstyrene (lines 4 to 6) are shown at a feed temperature of 100°C, with cumene to water weight ratios of 0.80 to 1.20 (lines 1, 4), 1.20 to 1.45 (lines 2, 5), and 1.45 to 1.70 (lines 3, 6). Detailed Implementation

[0020] This disclosure provides advantageous systems and methods for producing phenol, as well as improved systems and methods for separating phenol from product streams (e.g., from phenol product streams).

[0021] As noted, the cracked products of neutralized cumene hydroperoxide can be separated into a crude acetone fraction (top stream) and a crude phenol fraction (bottom stream) via a column (e.g., a distillation column). Generally, the capacity or throughput of a distillation column is primarily determined by the designed vapor flow (load) or the top distillate (OVHD), which moves upwards within the column and is enriched (e.g., maximally enriched) at the top of the column for volatile components. After condensation in a condenser, the top stream distilled from the top of the distillation column can be separated into a distillate obtained as the top product (e.g., crude acetone fraction) and reflux (which can be returned to the distillation column and has the same general composition as the distillate). The ratio of reflux to distillate is called the reflux ratio (R). A decrease in reflux results in a decrease in the reflux ratio (R). Therefore, at a constant distillation feed rate (capacity) and distillate, a reduction in reflux leads to a reduction in the top volume (reduced volumetric flow rate) and a corresponding reduction in the energy consumption of the method (reboiler load). With other column conditions equal, and a constant top distillate, reducing the reflux or reflux ratio (R) increases the feed rate (capacity) of the distillation column. This increase in feed rate (capacity) occurs because, according to the overall material balance of the column, the feed is divided into a top product selected as the distillate and a bottom product selected as the bottom stream, thereby simultaneously increasing the amounts of both the distillate (crude acetone fraction) and the bottom product (crude phenol fraction). Therefore, a significant reduction in reflux (R) results in a significant reduction in top distillate and, depending on the specified objective, allows for a significant reduction in process energy consumption and / or an increase in distillation column capacity (e.g., increasing the production of phenol and / or acetone products, or addressing both to varying degrees simultaneously).

[0022] The method disclosed herein for separating phenol from a phenol product stream avoids the problem of overloading the distillation column, thus maintaining column efficiency and significantly reducing impurity levels in the phenol product. This method can reduce the load on the distillation column and increase the efficiency of removing hydroxyacetone from the crude phenol fraction. To achieve this, two main factors are employed. First, the phenol product stream (e.g., from the hydroperoxide cumene decomposition stage (stage) of phenol production) is introduced into an evaporator unit for evaporation (e.g., flash evaporation via a flash unit) to remove acetone from the phenol product stream. A portion of the removed acetone can be recycled back to the hydroperoxide cumene decomposition stage as recycle acetone. The remaining removed acetone can bypass the distillation column and be directed to an acetone purification stage (e.g., an acetone purification train), and / or can be combined with acetone exiting the distillation column (crude acetone fraction). The combined stream can be directed to the acetone purification stage. Because it primarily reduces the acetone content in the feedstock, this method of using a bypass acetone stream (e.g., all other things being equal) not only allows for a reduction in the volumetric flow rate of the top stream from the distillation column by 8 to 17%, and / or a reduction in the volumetric feed rate to the distillation column by 6 to 13%, but also (due to the increased weight ratio of cumene to water in the column) increases the efficiency of removing hydroxyacetone from the crude phenol fraction. Secondly, maintaining a defined temperature profile in the distillation column (e.g., along sections of the column) allows for a significant reduction in the reflux ratio, from the range of 0.5 to 0.8 to less than 0.5 (e.g., to less than or equal to 0.40; as low as 0 to 0.1). Simulated mass balances of distillation columns used in conventional phenol plants for separating and neutralizing cracked mixtures allow for calculations of changes in mainstream components such as the top distillate (OVHD) and feed caused by the use of recirculated (bypass) acetone from the evaporator unit directly into the acetone purification column around the distillation column. The simulations considered the reduction in feed rate caused by using setpoint recirculation and the constancy of the reflux ratio with and without recirculation. According to the simulations (calculations), using 25% acetone recirculation in bypass form (total acetone recirculation from the evaporator unit) allowed for a topflow reduction of at least 8.5%, and a reduction of at least 17% when using 50% acetone recirculation from the evaporator unit. The determined temperature profile is the temperature profile along the column height showing an increase (e.g., greater than 98%) in the removal of hydroxyacetone from the bottom of the distillation column (crude phenol fraction).

[0023] Therefore, by using both factors simultaneously—namely, (i) a reduced reflux ratio by utilizing a bypass of acetone (e.g., a light acetone fraction) from the evaporator unit; and (ii) maintaining a defined temperature profile in the distillation column, with other conditions equal (e.g., constant)—the top flow volumetric velocity of the distillation column is reduced and / or the volumetric feed rate (capacity) is increased by at least about 30-40%. As shown in Table 3 below, reducing the reflux ratio (without using recycle material) only from 0.5 to 0.1 and to about 0 allows for a reduction in top flow of at least 24% and 30%, respectively. Using 50% recycle material (bypass) while reducing the reflux ratio allows for a further reduction in top flow, by at least 30% and 40%, respectively. Reducing the initial reflux ratio from about 0.6-0.8 (commonly accepted in some phenol plants in industry) to 0.1 to 0 results in even greater reductions in top flow. For example, and as further discussed below, compared to a distillation column having a reflux ratio greater than or equal to 0.5 and / or not selecting / bypassing at least 25 vol% of the bypass flow from the evaporator unit, the volumetric flow rate of the top stream of the distillation column of this disclosure can be reduced by greater than 25%, for example, greater than 35%. As will be shown in Table 3 below, reducing the reflux ratio (without using recycle material) only from 0.5 to 0.1 and to about 0 allows for a reduction in the top stream by at least 24% and 30%, respectively. Using 25% recycle material (bypass) while reducing the reflux ratio allows for a further reduction in the top stream, by up to 25% and 35%, respectively. Furthermore, compared to a distillation column with a reflux ratio greater than or equal to 0.5 and / or not selecting / bypassing at least 50 vol% of the bypass flow from the evaporator unit, the volumetric flow rate of the distillation feed stream of the distillation column of this disclosure can be increased by greater than 30%, for example, greater than 40%.

[0024] Furthermore, by using a defined temperature profile, regardless of the weight ratio of cumene to water varying from 0.8 to 1.7, the removal of hydroxyacetone from the bottom stream (e.g., from the crude phenol stream / fraction) was improved.

[0025] Through this process / method, the crude phenol stream / fraction (e.g., exiting the distillation column) can contain less than or equal to 25 ppm of hydroxyacetone, for example, less than or equal to 10 ppm, or even more specifically, less than or equal to 5 ppm. Furthermore, by increasing the temperature in the bottom stream (e.g., especially in the lower part of the distillation column), the crude phenol stream / fraction can contain less than or equal to 0.20 wt% of α-methylstyrene, for example, less than or equal to 0.10 wt%, or less than or equal to 0.05 wt%, or less than or equal to 0.01 wt%.

[0026] Acetone of ≥25 vol% from the top of the evaporator flash unit can be directly directed around the distillation column as a bypass acetone to acetone purification (e.g., to an acetone purification stage / group) and / or combined with crude acetone fractions, such as ≥50 vol% from the top of the evaporator flash unit. Therefore, compared to a distillation column having a reflux ratio of ≥0.25 and not selecting / bypassing at least 25 vol% of the bypass stream from the evaporator unit, the volumetric flow rate of the top stream of the distillation column of this disclosure can be reduced by ≥15%, for example, ≥25%. Compared to a distillation column having a reflux ratio of ≥0.5 and not selecting / bypassing at least 25 vol% of the bypass stream from the evaporator unit, the volumetric flow rate of the top stream of the distillation column can be reduced by ≥25%, such as ≥35%.

[0027] According to this method, the evaporator unit feed stream (e.g., the phenol product stream) can pass through the evaporator unit. The evaporator unit feed stream (e.g., the phenol product stream) may contain pyrolyzed / decomposed cumene hydroperoxide. For example, the evaporator unit feed stream (e.g., the phenol product stream) may contain phenol, acetone, water, cumene, α-methylstyrene, hydroxyacetone, 2-methylphenylfuran, or a combination containing at least one of the above. The evaporator unit may be a flash evaporator unit, such as a reused cumene hydroperoxide decomposition reactor, a short column evaporator, or another type of evaporator. A bypass stream containing acetone may be discharged from the top of the evaporator unit as bypass / recycled acetone.

[0028] A bottom fraction containing acetone and phenol can be discharged from the bottom of the evaporator unit. For example, the bottom fraction can be neutralized with a base reagent such as a caustic soda or a basic hydroxide to form a distillation feed stream. For example, the distillation feed stream can contain 10 wt% to 20 wt% of cumene and / or α-methylstyrene, for example, 11 wt% to 16 wt% or 12 wt% to 15 wt%. The distillation feed stream can also contain less than or equal to 2,200 ppm of hydroxyacetone, for example, 500 to 1,700 ppm or 1,000 to 1,400 ppm. The distillation feed stream can also contain a cumene to water weight ratio of 0.5 to 2, for example, 0.8 to 1.7, or 1.3 to 1.6. The temperature of the distillation feed stream can be 60°C to 120°C, for example, 75°C to 110°C, or 95°C to 110°C, for example, 100°C.

[0029] A distillation feed stream can be passed through a distillation column. For example, a distillation column can be a packed bed column or a column with internal trays. A distillation column includes a rectification section and a stripping section. In a non-limiting example, the distillation feed stream can be fed into the distillation column between the rectification section and the stripping section.

[0030] A distillation column may include a condenser, reflux tank, reboiler, gas distributor, reflux liquid distributor, feed plate, vacuum jacket, internal thermocouples positioned along the height of the distillation column, helical prismatic packing, automated flow rate controller, automated temperature controller, automated pressure controller, automated level controller, automated composition controller, or a combination thereof. The height of the packing layer can be adjusted to regulate the number of trays and their position within the distillation column. The distillation column may include computer-controlled pumps. These pumps can control distillation column parameters, such as the flow rates of the streams entering and leaving the distillation column. For example, the distillation column and associated streams may be heated using proportional-integral-derivative (PID) controlled electronic heaters and / or reboilers (e.g., steam, oil, and / or electrical).

[0031] A distillation column includes mass transfer devices (e.g., packing and / or trays) for separating the designed quantity of the distillation feed stream. The distillation column may include multiple mass transfer devices. For example, the distillation column may contain 40-55 total equilibrium stages or theoretical trays equivalent to 54-75 total actual mass transfer devices (e.g., trays). It should be noted that in the rectification section of the distillation column, 5-18 of the total equilibrium stages or theoretical trays (10-25 actual trays) may be located above the distillation feed stream.

[0032] The reflux ratio of the distillation column can be less than or equal to 1, for example, less than or equal to 0.8, or for example, less than or equal to 0.5. Due to this method, the reflux ratio can be less than or equal to 0.40, for example, less than or equal to 0.2, or less than or equal to 0.1, such as 0 to 0.1. The reflux temperature of the distillation column can be from 45°C to 75°C, for example, 49°C to 50°C. The distillation column can be operated at atmospheric pressure. The distillation column can also be operated under reduced pressure. Optionally, the distillation column can be operated under elevated pressure.

[0033] The distillation column (e.g., a packed bed distillation column) may include a total equilibrium stage or theoretical plate of height “H”, measured from the top of the highest equilibrium stage or theoretical plate (or other mass transfer device) to the bottom of the lowest equilibrium stage or theoretical plate (or other mass transfer device). The distillation column may further include temperature control points located on the column as a percentage of H. For example, the location of the temperature control points may be determined by “%H”. i "This represents the percentage of H as determined by equation (1):

[0034] %H i =(TT) i / ∑TT(1),

[0035] Among them, "(TT)" i“∑TT” represents the equilibrium stage or theoretical plate (or other equivalent mass transfer device) in the distillation column, and “∑TT” represents the total number of equilibrium stages or theoretical plates in the distillation column plus 1.

[0036] Equation (2) can be used to calculate the temperature profile at any temperature control point (any equilibrium stage or theoretical or actual tray or other equivalent mass transfer device):

[0037] T(H)=C1H 3 +C2H 2 +C3H+C4(2),

[0038] The equation is a piecewise polynomial function over the interval [0; 100], and "C" is the cubic Hermite interpolation (for each subinterval of T(H), cubic Hermite interpolations are provided in Table 5). The temperature at the control point can be controlled by adjusting the temperature of the distillation feed stream, the reflux temperature of the distillation column, the reflux ratio of the distillation column, the heat applied to the bottom of the distillation column, or a combination of at least one of the foregoing.

[0039] A distillation column may include one or more control points. For example, according to equations (1) and (2), a first temperature control point may be located above the distillation feed inlet of the distillation column, in the rectification section of the distillation column, at a height of 15% to 25% of H, wherein the temperature of the first temperature control point is 80°C to 125°C. A second temperature control point may be located below the distillation feed inlet of the distillation column, in the stripping section of the distillation column, at a height of 25% to 35% of H, wherein the temperature of the second temperature control point is 150°C to 165°C. A third temperature control point may be located below the distillation feed inlet of the distillation column, in the stripping section of the distillation column, at a height of 40% to 60% of H, wherein the temperature of the third temperature control point is 150°C to 175°C, for example, 165°C to 170°C. The fourth temperature control point can be located below the feed inlet of the distillation column, in the stripping section of the distillation column, at a height of 65% to 90% of H, where the temperature of the fourth temperature control point is between 160°C and 180°C, for example, 165°C to 175°C. The temperature can be adjusted when the distillation column is operated under non-atmospheric pressure.

[0040] A distillation column can separate a distillation feed stream into products of phenol and acetone, byproducts, and unreacted cumene for recycling. For example, this method may include distributing a crude acetone fraction to the top of the distillation column and a crude phenol fraction to the bottom of the distillation column. The crude acetone fraction may be discharged from the top of the distillation column. Optionally, at least a portion of the crude acetone fraction may be combined with bypass acetone from an evaporator unit to form a combined crude acetone fraction. The crude acetone fraction from the distillation column may contain less than or equal to 0.20 wt% phenol, for example, less than or equal to 0.10 wt%, for example, less than or equal to 0.05 wt%, for example, less than or equal to 0.01 wt%.

[0041] The crude phenol fraction can be discharged from the bottom of the distillation column. The crude phenol fraction may contain less than or equal to 25 ppm of hydroxyacetone, for example, less than or equal to 10 ppm, or for example, less than or equal to 5 ppm. The crude phenol fraction (e.g., due to the near-complete absence of hydroxyacetone) may contain less than or equal to 10 ppm of 2-methylbenzofuran, for example, less than or equal to 5 ppm of 2-methylbenzofuran, or for example, 0 ppm of 2-methylbenzofuran.

[0042] The temperature of the crude phenol fraction can be between 181°C and 190°C, for example, 182°C to 187°C or 183°C to 185°C. The crude phenol fraction can undergo further downstream processing, such as producing high-quality phenol, and then producing polycarbonate.

[0043] A more complete understanding of the components, processes, and apparatus disclosed herein can be obtained by referring to the accompanying drawings. These drawings (also referred to herein as “Figures”) are merely schematic diagrams for convenience and ease of illustrating this disclosure and are therefore not intended to represent the relative size and dimensions of the device or its components and / or to define or limit the scope of the exemplary embodiments. Although certain terms are used in the following description for clarity, these terms are intended to refer only to the specific structures chosen for the embodiments illustrated in the drawings and are not intended to define or limit the scope of this disclosure. In the drawings and the following description, it should be understood that the same numerical reference numerals refer to components having the same function.

[0044] Now for reference Figure 1 This schematic diagram represents an exemplary system configuration 10 used in methods for producing phenol and / or for separating phenol from a product stream. System configuration 10 may include passing an evaporator unit feed stream 12 (e.g., a phenol product stream 12) containing phenol and acetone through an evaporator unit 14.

[0045] A bypass stream or bypass acetone 16 (e.g., including a portion of the total light acetone fraction) can be discharged from the top 18 of evaporator unit 14. Residual portions of acetone fraction 42 (e.g., light acetone fraction 42, including a portion of the total light acetone fraction) can be recycled back to the cracking stage.

[0046] System configuration 10 may include discharging bottom fraction 22 from evaporation unit 14, neutralizing the bottom fraction in neutralization unit 38 to form distillation feed stream 20 containing acetone and phenol, and passing distillation feed stream 20 through distillation column 24. System configuration 10 may include distributing crude acetone fraction to the top 28 of column 24 and crude phenol fraction to the bottom 32 of distillation column 24.

[0047] Distillation column 24 may include mass transfer devices (e.g., a balance stage or one or more theoretical plates or structured packing) of height “H” measured from the top of the highest mass transfer device of distillation column 24 to the bottom of the lowest mass transfer device of distillation column 24. Distillation column 24 may further include temperature control points 36 located on distillation column 24 at a certain percentage of H.

[0048] After condensation in condenser 40, the top stream distilled from the top 28 of distillation column 24 can be divided into distillate 26, which is obtained as a top product (e.g., crude acetone fraction 26), and reflux (not shown), which can be returned to distillation column 24 and has the same general composition as distillate 26.

[0049] Distillate / crude acetone fraction 26 may be discharged from condenser 40, and phenol product stream 30 (e.g., crude phenol fraction 30) may be discharged from the bottom 32 of distillation column 24. Crude acetone fractions 26 and 34 are directed to acetone purification unit 44, and crude phenol fraction 30 is introduced to phenol purification unit 46. System configuration 10 may include combining bypass stream 16 and crude acetone fraction 26 from distillation column 24 to form combined acetone stream 34, which can be directly directed to acetone purification unit 44. It should be noted that, regardless of its composition, all or part of bypass stream 16 may be introduced separately from crude acetone fraction 26 to the desired point in acetone unit 44.

[0050] The following examples are merely illustrative of the methods for producing phenol disclosed herein and are not intended to limit the scope thereof.

[0051] Example

[0052] According to, as in Figure 1The typical system configuration 10 described above is used for experimental testing of a continuous-mode, laboratory-scale packed-bed distillation column for the production of phenol and / or for the separation of phenol from the product stream. The distillation column is equipped with a vacuum jacket, five internal thermocouples positioned along its height, and helical prismatic packing. The height of the packing layer is adjusted to control the number of trays and their positions within the column. The column is also equipped with five automated, computer-controlled pumps. These pumps control distillation column parameters, such as the flow rates of the streams entering and leaving the column. The distillation column and associated streams are heated using a sand bath and a PID-controlled electronic heater. After achieving steady-state conditions (constant fluid flow rate, stable temperature profile), parameters are varied, and multiple samples are collected at predetermined time intervals. Samples are analyzed using an HP-5890 Series II chromatograph.

[0053] Table 1 provides the main operating parameters of the distillation column and the flow composition of the feed stream (feed), crude acetone stream, and crude phenol fraction (bottom fraction (BTM)). In Table 1, 80 (#49), 51 (#31), 31 (#18), and 17 (#9) are the locations of temperature control points on the distillation column (percentage of height H and the corresponding number of trays in parentheses). The corresponding temperatures are then listed below. The temperature of the crude phenol fraction is controlled by an external temperature controller. Table 2 provides the feed composition. In Tables 1 and 2, Examples 1-6 and Comparative Examples 1-5 utilized feedstock taken from a full-scale phenol production facility. Examples 7-26 and Comparative Examples 6 and 7 used artificial mixtures in which the weight ratio of cumene to water was 0.8 to 1.2 (Examples 7 to 17, 25, 26, Comparative Examples 6 and 7), 1.20-1.45 (Examples 18 to 21), and 1.45-1.70 (Examples 22 to 24). Artificial mixtures in Examples 18 to 21 and Examples 22 to 24 were prepared by initially selecting acetone bypass streams (above or below 25%) and above acetone bypass streams (above or below 50%) from the total recirculated acetone stream from the evaporator flash unit.

[0054] Examples using feedstocks and examples with varying weight ratios of cumene to water from 0.8 to 1.2 were relatively unstable in laboratory settings. For example, in Examples 1 and 2, with feed rates equal to approximately 400 mL / hr, the desired so-called “defined” temperature profiles were maintained (e.g., which provided improved results), and the hydroxyacetone content in the crude phenol fraction was 5.3 to 13.5 parts per million (ppm). In Comparative Examples 1 and 2, defined temperature profiles were not maintained, and in Comparative Example 1, the distillation column overflowed. In Examples 3 to 6 (feed rates increased to 466 to 484 mL / hr, maintaining a reflux ratio of 0 to 0.1), defined temperature profiles for hydroxyacetone removal were maintained, and the hydroxyacetone content in the crude phenol fraction decreased to 2 to 18 ppm. In Comparative Examples 3 to 5, reflux ratios of 0.55 and 0 (e.g., no external reflux) were used, but a defined temperature profile was not maintained and was lower than expected, and the hydroxyacetone content in the crude phenol fraction increased to 65 to 614 ppm.

[0055] Examples 1 to 26 demonstrate that, while maintaining a defined temperature profile, the hydroxyacetone content in the crude phenol fraction typically does not exceed 20 ppm, such as less than 10 ppm, and more particularly less than 5 ppm. If the temperature of the crude phenol fraction (bottom stream) is increased to 183.7°C or higher and the temperature on tray #49 in the lower portion of the stripping section is slightly increased, the α-methylstyrene content in the crude phenol fraction can be reduced to less than 0.20 wt% (Examples 16 and 19), such as less than 0.10 wt% (Examples 7, 9, 11, and 17). Simultaneously, when the weight ratio of cumene to water varies from 0.80 to 1.20, the phenol content in the distillate does not exceed 0.10 wt% (Examples 3, 7, and 8), for example, less than 0.05 wt% (Examples 1, 2, 4-6, and 9-17).

[0056] Furthermore, if the temperatures at the remaining control points match the established temperature profiles (Examples 1-6, 8, 10, 12-15, 18, and 20-26), lowering the temperature of the crude phenol fraction below the temperature required for α-methylstyrene removal does not affect the efficiency of hydroxyacetone removal, but it does reduce the efficiency of α-methylstyrene removal. Lowering the temperature profile at other control points different from the crude phenol fraction (Comparative Examples 1 to 6), and raising the temperature (Comparative Example 7), resulted in a decrease in the efficiency of hydroxyacetone removal.

[0057] The data in Table 1 also show that in Examples 7, 9, 11, 16, 17, and 19, a defined temperature profile was maintained for the simultaneous removal of HA and AMS, with the HA content in the crude phenol stream not exceeding 5.5 ppm and the AMS content less than 0.2 wt%, for example, less than or equal to 0.1 wt%. The main difference between the defined temperature profile for HA removal and the defined temperature profile for the simultaneous removal of HA and AMS is that, for the simultaneous removal of HA and AMS, the temperature in the bottom stream and the lower portion of the stripping section (e.g., on tray #49) can be appropriately increased. However, despite almost complete removal of AMS, the significant increase in temperature on trays #49 and #31 caused HA (447 ppm) to fall into the bottom stream (Comparative Example 7).

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] Use acetone bypass flow or bypass acetone (16); Figure 1 This not only reduces the distillation column (24; Figure 1The volumetric flow rate of the top stream also allows for an increase in the weight ratio of cumene to water, a decrease in the acetone and water content of the feed stream, and an increase in the efficiency of removing hydroxyacetone from the crude phenol fraction. In some phenol units, at the decomposition stage of CHP, a recycle of acetone (recycle stream) is used to provide necessary heat removal during its evaporation to remove the heat of reaction. This recycle is formed in the evaporation unit and is a condensed vapor fraction mainly containing acetone. The bottom product from the evaporation unit is sent to the neutralization stage and then used as feed to the distillation column to separate it into fractions. Thus, a quasi-stationary composition of the column feed is established in this system. When only a portion of the recycle (from the total recycle flowing to the decomposition stage) is removed and directly directed to the feed of the column of the acetone purification column via a bypass around the distillation column, firstly, the content of acetone and water decreases, the content of phenol and cumene increases, and the changes in the remaining components are not significant (see Table 2 below). That is, using a recycle (bypass) increases the weight ratio of cumene to water, which is an important feed parameter affecting the removal efficiency of hydroxyacetone. For example, if the average weight ratio of cumene to water in the initial feed (without a recycle bypass) is about 1.0, then using 25% and 50% recycle (bypass) increases this ratio to an average of about 1.3 and 1.6, respectively. Using recycle from the evaporator flash unit (14; Figure 1 The total recycle / bypass acetone flow of ≥25 vol% and ≥50 vol% of acetone bypass flow make the column (24; Figure 1 The volumetric flow rate of the top flow of the distillation column (24) was reduced by 8% and 17%, respectively, or the volumetric flow rate of the distillation feed flow was reduced by at least 6% and at least 13%, respectively, due to the main reduction in the volumetric flow rate of the distillation column (24). Figure 1 ) raw material feed (20; Figure 1 The acetone content in the acetone. Simulated mass balance of the distillation column used in a conventional phenol plant for separating and neutralizing the cracked mixture allows calculation of changes in mainstream components such as top distillate (OVHD) and feed due to the use of recirculated (bypass) acetone from the evaporator unit directly into the acetone purification column surrounding the distillation column. Simulations are performed considering the reduction in feed rate caused by using setpoint recirculation and the constancy of the reflux ratio with and without recirculation. According to the simulation (calculation results), using 25% acetone recirculation in the form of a bypass (total acetone recirculation from the evaporator unit) allows for a reduction of at least 8.5% in the top stream, and at least 17% when using 50% acetone recirculation from the evaporator unit.

[0065] Furthermore, the weight ratio of cumene to water increased from an average of 1.05 to 1.3 and 1.6, respectively. The maintenance of the defined temperature profile also allows for the use of lower reflux ratios over a wide range of feed temperatures (e.g., 80 to 110 °C) and compositions (e.g., a weight ratio of cumene to water of 0.8 to 1.7).

[0066] Tables 3 and 4 show the dependence of the top crude acetone fraction (OVHD) on the feed rate of the distillation column (where the weight ratio of cumene to water varies from 0.8 to 1.20) and the reflux ratio. The distillation column feed rate and feed stream composition have no significant effect on the top fraction, while the reflux ratio has a significant effect on the top fraction (OVHD). This configuration allows for a reduction in the top stream / fraction volumetric flow rate greater than or equal to 44%. The data in Tables 3 and 4 also demonstrate that if the reflux ratio (“R”) is reduced while maintaining the crude acetone stream (OVHD) flow rate and a defined temperature profile, the volumetric feed rate (F) can be increased greater than or equal to 30%, thus allowing for a significant increase in the distillation column capacity. Average data are provided in Table 3.

[0067] OVHD = Distillate + Reflux

[0068] Reducing the reflux ratio from 0.5 (e.g., as used in an exemplary full-scale phenol production facility) to 0.1 and 0 (e.g., no external reflux) reduces the top flow (OVHD) volumetric flow rate by an average of 24% and 30%, respectively. Reducing the reflux ratio from 0.8 (e.g., as used in an exemplary full-scale phenol production facility) to 0 reduces the top flow (OVHD) volumetric flow rate even more; by up to 44%. Moreover, by reducing the reflux ratio from 0.25 to 0.1 and 0, this results in an average reduction of 8% and 17% in the top flow (OVHD) volumetric flow rate, respectively.

[0069] The data in Table 4 confirm that increasing the feed rate from 400 ml / hr (R = 0.5) to 480 ml / hr, and then to 530 ml / hr, while decreasing R from 0.5 to 0.1 or to 0, allows OVHD to decrease from 334.8 ml / hr (400 ml / hr, R = 0.5) to 286.4 ml / hr (480 ml / hr, R = 0) and to 308 ml / hr (480 ml / hr, R = 0.1), and to 317.8 ml / hr (530 ml / hr, R = 0) and to 329.9 ml / hr (530 ml / hr, R = 0.1), respectively (e.g., OVHD decreases by 8 to 14.5% (480 ml / hr) and 1.5 to 5.1% (530 ml / hr)). Therefore, reducing the reflux ratio from 0.5 to 0.1 and 0 at a constant load (OVHD flow rate) will allow the feed rate to increase from about 400 ml / hr to about 480 ml / hr (an increase of 20%) and even up to about 530 ml / hr (an increase of 30%), while maintaining a defined temperature profile in the distillation column to increase the efficiency of hydroxyacetone removal.

[0070]

[0071] The "+" symbol indicates an increase in OVHD.

[0072] It is also taken into consideration that the pre-selection comes from the evaporator flash unit (14); Figure 1 The bypass acetone fraction (e.g., light acetone fraction 16) and the reflux ratio reduced from 0.8 to 0.5 to 0.1 or even to 0 (without external reflux) while maintaining a defined temperature profile in the distillation column, thereby allowing the distillation column capacity (feed flow rate) to be increased by more than or equal to 30%, for example, more than or equal to 40%, which significantly increases the production of phenol and acetone products.

[0073] Referring back to the data obtained in Tables 1 to 4, the determined temperature profile may include: (i) a first temperature control point located on the distillation column, above the feed inlet, in the rectification section of the distillation column, at a height ranging from 15% to 19% of H (the total height "H" measured from the top to the bottom of the distillation column), wherein the temperature of the first temperature control point is between 84°C and 118°C; and (ii) a second temperature control point located on the distillation column, below the feed inlet, in the stripping section of the distillation column, at a height ranging from 28% to 34% of H. The distillation column has the following temperature control points: (i) a second temperature control point at a height of 155°C to 165°C; (ii) a third temperature control point at a height of 46% to 56% of H, located on the distillation column, below the feed inlet, in the stripping section of the distillation column; and (iv) a fourth temperature control point at a height of 75% to 85% of H, located on the distillation column, below the feed inlet, in the stripping section of the distillation column; and (v) a fourth temperature control point at a height of 165°C to 173°C. The distillation column can operate at atmospheric pressure with a feed temperature of 100°C.

[0074] It should be noted that the determined temperature profiles for the simultaneous removal of hydroxyacetone and α-methylstyrene are similar, except that the bottom temperature increases to 183.7°C to 185°C, and the temperature at the fourth temperature control point also increases.

[0075] It was also noted that as the total number of mass transfer devices in the distillation column increased, the position of the control points shifted downwards relative to the distillation column; and as the total number of mass transfer devices in the distillation column decreased, the position of these control points shifted upwards relative to the distillation column.

[0076] It should also be noted that when the feed stream temperature decreases from 110°C to 85°C, and the weight ratio of cumene to water varies from 0.8 to 1.2, the temperature profiles determined at the bottom stream and all control points do not undergo any significant changes and show only a slight decrease. The phenol content in the top stream (distillate) does not exceed 0.10 wt%, and is less than 0.05 wt%, more specifically about 0%. When the weight ratio of cumene to water in the feed stream varies from 1.2 to 1.45, the temperature profiles determined at the bottom stream and control points in the stripping section remain essentially unchanged; however, in the refining section, the control point temperatures increase slightly on average to 116 to 126°C. The phenol content in the distillate does not exceed 0.10 wt%, and is less than or equal to 0.06 wt%. When the weight ratio of cumene to water in the feed stream varied from 1.45 to 1.70, the determined temperature profile changed only in the refining section of the distillation column (above the feed stream inlet, in the rectification section of the distillation column); the control point at 15% to 19% of H increased to 121°C to 139°C. The phenol content in the top stream did not increase significantly and did not exceed 0.20 wt%, such as less than 0.15 wt%.

[0077] Figure 2 This indicates that the product from column 24 is used in methods for producing phenol and / or for separating phenol from the product stream. Figure 1 The determined temperature curve data were plotted. Six datasets were examined at a feed temperature of 100°C. Therefore, empirical equations were obtained that allow the calculation of determined temperature curves at any temperature control point on the column. The datasets are provided in Table 5. Determined temperature curves for the removal of hydroxyacetone are shown in datasets 1 to 3. Determined temperature curves for the removal of both hydroxyacetone and α-methylstyrene are shown in datasets 4 to 6. The weight ratio of cumene to water varied from 0.80–1.20 (datasets 1, 4), from 1.20–1.45 (datasets 2, 5), and from 1.45–1.70 (datasets 3, 6). Therefore, the equation T(H) = C1H can be used. 3 +C2H 2 +C3H+C4 calculates the defined temperature profile for any temperature control point (any equilibrium stage or theoretical or practical plate), where the equation is a piecewise polynomial function over the interval [0; 100], and “C” is the cubic Hermitian interpolation. “H” is the total height measured from the top to the bottom of the distillation column. Cubic Hermitian interpolations are provided in Table 5 for each subinterval of T(H).

[0078]

[0079]

[0080] The methods and processes disclosed herein include at least the following aspects and / or implementation methods:

[0081] Aspect 1: A method for separating phenol, comprising separating a first portion of acetone from a product stream in an evaporator unit, wherein the first portion of acetone comprises recycled acetone and bypass acetone; recycling the recycled acetone; discharging a bottom fraction from the evaporator unit; neutralizing the bottom fraction to form a distillation feed stream, the distillation feed stream being directed to a distillation column; separating the distillation feed stream into a bottom stream and a top stream, the bottom stream comprising a crude phenol fraction; passing the top stream through a condenser to produce a distillate as a crude acetone fraction, and wherein the reflux ratio of the distillation column is less than or equal to 0.4, wherein the reflux ratio is the ratio of the weight of the reflux to the weight of the distillate; and guiding bypass acetone around the distillation column.

[0082] Aspect 2: The method according to aspect 1 further includes combining the crude acetone fraction with bypass acetone to form a combined stream; purifying the combined stream to produce an acetone product; and purifying the crude phenol fraction to produce phenol.

[0083] Aspect 3: The method according to any of the preceding aspects, wherein the bypass acetone comprises a first portion of acetone separated from the product stream of greater than or equal to 25 vol%, such as greater than or equal to 35 vol%, more particularly greater than or equal to 50 vol%.

[0084] Aspect 4: The method according to any of the preceding aspects, wherein the reflux ratio of the distillation column is less than or equal to 0.2, such as less than or equal to 0.1, more particularly 0 to 0.1.

[0085] Aspect 5: The method according to any of the preceding aspects, wherein the distillation feed stream comprises 10 wt% to 20 wt% of cumene or α-methylstyrene or combinations thereof, such as 11 wt% to 16 wt% of cumene or α-methylstyrene or combinations thereof; and wherein the distillation feed stream comprises 500 to 2,000 ppm of hydroxyacetone, such as 1,000 to 1,400 ppm of hydroxyacetone.

[0086] Aspect 6: The method according to any of the preceding aspects, wherein the temperature of the distillation feed stream is 60°C to 120°C, such as 75°C to 110°C, more particularly 100°C.

[0087] Aspect 7: The method according to any of the preceding aspects, wherein the distillation feed stream comprises a weight ratio of 0.5 to 2.0, such as 0.8 to 1.7, more particularly 1.3 to 1.6 of cumene to water.

[0088] Aspect 8: The method according to any of the preceding aspects, wherein the crude acetone fraction contains less than or equal to 0.20 wt% phenol, such as less than or equal to 0.10 wt% phenol, more particularly less than or equal to 0.05 wt% phenol, or even more particularly less than or equal to 0.01 wt% phenol.

[0089] Aspect 9: The method according to any of the preceding aspects, wherein the reflux of the distillation column has a temperature of 45°C to 75°C, such as 49°C to 50°C.

[0090] Aspect 10: The method according to any of the preceding aspects, wherein the crude phenol fraction contains less than or equal to 25 ppm of hydroxyacetone, such as less than or equal to 10 ppm of hydroxyacetone, more particularly less than or equal to 5 ppm; and wherein the crude phenol fraction contains less than or equal to 0.20 wt% of α-methylstyrene, such as less than or equal to 0.10 wt% of α-methylstyrene, more particularly less than or equal to 0.05 wt% of α-methylstyrene, and even more particularly less than or equal to 0.01 wt% of α-methylstyrene.

[0091] Aspect 11: The method according to any of the preceding aspects, wherein the temperature of the crude phenol fraction is 181°C to 190°C, such as 182°C to 187°C, more particularly 183°C to 185°C.

[0092] Aspect 12: The method according to any of the preceding aspects, wherein the volumetric flow rate of the top flow of the distillation column is reduced by more than or equal to 25%, for example, more than or equal to 35%, compared with a distillation column having a reflux ratio greater than or equal to 0.50; and wherein the volumetric flow rate of the distillation feed flow of the distillation column is increased by more than or equal to 30%, for example, more than or equal to 40%, compared with a distillation column having a reflux ratio greater than or equal to 0.50.

[0093] Aspect 13: The method according to any of the preceding aspects, wherein the product stream is a cumene hydroperoxide cracking product stream; and wherein recycled acetone is recycled to the cumene hydroperoxide cracking stage.

[0094] Aspect 14: The method of aspect 1 further includes directly directing bypass acetone to the acetone purification stage.

[0095] Aspect 15: The method according to any of the preceding aspects, wherein the distillation column further comprises 40-55 total balance stages or theoretical plates equivalent to 55-75 total actual plates, and wherein 5-20 of the total balance stages or theoretical plates equivalent to 10-25 actual plates are located in the rectification section above the inlet of the distillation feed stream.

[0096] Aspect 16: The method according to any of the preceding aspects, wherein the distillation column further includes a total height “H” measured from the top to the bottom of the distillation column; a first temperature control point located above the inlet of the distillation feed stream at a height of 15% to 25% of H, wherein the temperature of the first temperature control point is 80°C to 125°C; a second temperature control point located below the inlet at a height of 25% to 35% of H, wherein the temperature of the second temperature control point is 150°C to 165°C; a third temperature control point located below the inlet at a height of 40% to 60% of H, wherein the temperature of the third temperature control point is 150°C to 175°C, such as 165°C to 170°C; and a fourth temperature control point located below the inlet at a height of 65% to 90% of H, wherein the temperature of the fourth temperature control point is 160°C to 180°C, such as 165°C to 175°C.

[0097] Aspect 17: The method according to any of the foregoing aspects further includes maintaining a defined temperature profile along a section of the distillation column.

[0098] Aspect 18: According to the method of aspect 17, wherein the temperature profile is determined by adjusting at least one of the following: adjusting the composition of the distillation feed stream, such as adjusting the composition of the distillation feed stream to a weight ratio of 1.1 to 1.6 of cumene to water; adjusting the temperature of the distillation feed stream, such as 95°C to 105°C; adjusting the reflux temperature, such as 49°C to 51°C; adjusting the reflux ratio, such as less than or equal to 0.1; or adjusting the heat applied to the bottom of the distillation column.

[0099] Aspect 19: According to the method of Aspect 1, wherein the temperature of the distillation feed stream is 90°C to 110°C; wherein the distillation feed stream comprises a weight ratio of 0.8 to 1.7 of cumene to water; and further comprising maintaining a defined temperature profile along a section of the distillation column, wherein the temperature of the temperature control point of the distillation column is represented by a piecewise polynomial function T(H) over the interval [0; 100], and in each subinterval “T(H)” is a cubic Hermitian interpolation: T(H) = C1H 3 +C2H 2 +C3H+C4, where “C1”, “C2”, “C3”, and “C4” are the coefficients for each subinterval.

[0100] Aspect 20: According to the method of Aspect 1, wherein the distillation column includes a temperature control point and a total equilibrium stage of height “H” measured from the top of the highest equilibrium stage of the distillation column to the bottom of the lowest equilibrium stage of the distillation column, wherein the location of the temperature control point is a percentage of H expressed as “%Hi” and determined by the following equation: %H i =(TT) i / ∑TT; where “(TT)i” is the balance level and “∑TT” is the total number of balance levels in the tower + 1.

[0101] Aspect 21: The method according to any of the preceding aspects, wherein the distillation column further comprises 54-75 trays, wherein 10-25 trays are located above: (i) the inlet of the distillation feed stream, and (ii) in the rectification section.

[0102] Aspect 22: The method according to any of the preceding aspects, wherein the distillation column is operated at atmospheric pressure.

[0103] Aspect 23: A method for producing high-quality phenol, comprising: separating a light acetone fraction as a top fraction from a flash evaporator unit in a cumene hydroperoxide cracking stage; directly guiding a first portion of the light acetone fraction as bypass acetone to an acetone purification column around a distillation column; returning a residual portion of the light acetone fraction as a recycle acetone fraction to the cumene hydroperoxide cracking stage; discharging a bottom fraction from the flash evaporator unit; neutralizing the bottom fraction; introducing the neutralized bottom fraction as a distillation feed stream into a distillation column; separating the distillation feed stream into a top stream and a bottom stream in the distillation column, the top stream containing a crude acetone fraction and the bottom stream containing a crude phenol fraction; and guiding the crude acetone fraction... The acetone purification column is used to produce acetone; the crude phenol fraction is directed to the phenol purification column to produce high-quality phenol; the distillation column is operated with a reflux ratio less than or equal to 0.4, such as less than or equal to 0.1, where the reflux ratio is the ratio of the weight of the reflux to the weight of the distillate; the distillation column is operated using a defined temperature profile, and wherein the distillation column includes a temperature control point and a total equilibrium stage of height “H” measured from the top of the highest equilibrium stage to the bottom of the lowest equilibrium stage, wherein the temperature of the temperature control point is represented by a piecewise polynomial function T(H) over the interval [0; 100]; and “T(H)” is a cubic Hermitian interpolation over each subinterval:

[0104] T(H)=C1H 3 +C2H 2 +C3H+C4,

[0105] Where “C” is the coefficient of each sub-interval;

[0106] The crude phenol fraction contains less than or equal to 25 ppm of hydroxyacetone, such as less than or equal to 10 ppm of hydroxyacetone, more particularly less than or equal to 5 ppm; and the crude phenol fraction contains less than or equal to 0.20 wt% of α-methylstyrene, such as less than or equal to 0.10 wt% of α-methylstyrene, more particularly less than or equal to 0.05 wt% of α-methylstyrene, and even more particularly less than or equal to 0.01 wt% of α-methylstyrene.

[0107] Aspect 24: The method of Aspect 23, wherein the determined temperature profile allows for improved reflux ratio reduction and improved removal of hydroxyacetone or simultaneous removal of hydroxyacetone and α-methylstyrene, and the removal is regulated by distillation feed stream and / or reflux temperature and / or by reflux ratio and / or by heat applied to the bottom of the distillation column.

[0108] In general, this disclosure may alternatively include, consist of, or substantially consist of any suitable components disclosed herein. This disclosure may be formulated additionally or alternatively to be free of or substantially free of any components, materials, ingredients, adjuvants, or substances used in prior art compositions or otherwise not essential for achieving the function and / or purpose of this disclosure. The endpoints of all ranges for the same components or properties are included and can be combined independently (e.g., the range “less than or equal to 25 wt%, or 5 wt% to 20 wt%” includes the endpoints of the range “5 wt% to 25 wt%” and all intermediate values, etc.). Disclosing a narrower range or a more specific group, in addition to a broader range, does not preclude a broader range or a larger group. “Combination” includes blends, mixtures, alloys, reaction products, etc. Furthermore, the terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to indicate that one element is distinguished from another. Unless otherwise indicated herein or clearly contradicted by the context, the terms “a,” “an,” and “the” used herein do not imply a limitation of quantity and are to be construed as encompassing both the singular and plural. “Or” means “and / or.” The suffix “(s)” as used herein is intended to include both the singular and plural of the term it modifies, thereby including one or more of that term (e.g., membrane(s) includes one or more membranes). Throughout the specification, references to “one embodiment,” “another embodiment,” “implementation,” etc., indicate that a particular element (e.g., feature, structure, and / or characteristic) described in connection with an embodiment is included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the described elements may be combined in any suitable manner in various embodiments.

[0109] The modifier “about” used with quantities includes the value and has a context-specific meaning (e.g., including the degree of error associated with a particular quantity of measurement). The symbol “+10%” indicates that the measurement can range from -10% to +10% of the value. Unless otherwise stated, the terms “before,” “after,” “bottom,” and / or “top” are used for descriptive convenience only and are not limited to any particular location or spatial orientation. Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. “Combination” includes blends, mixtures, alloys, reaction products, etc.

[0110] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if any terminology in this application contradicts or conflicts with terminology in the incorporated references, the terminology from this application shall take precedence over the conflicting terminology from the incorporated references.

[0111] While specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents may be conceived by the applicant or others skilled in the art that are currently unforeseeable or likely to be unforeseeable. Therefore, the appended claims, as filed and as they may be modified, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. A method for separating phenol, comprising: In the evaporator unit, a first portion of acetone is separated from the product stream, wherein the first portion of acetone includes recycled acetone and bypass acetone; The acetone is then recycled. The bottom fraction is discharged from the evaporator unit; The bottom fraction is neutralized to form a distillation feed stream, which is then directed to the distillation column. The distillation feed stream is separated into a bottom stream and a top stream, the bottom stream containing a crude phenol fraction; The top stream is passed through a condenser to produce a distillate as a crude acetone fraction, and the reflux ratio of the distillation column is less than or equal to 0.4, wherein the reflux ratio is the ratio of the weight of the reflux to the weight of the distillate. as well as The bypass acetone is guided around the distillation column.

2. The method according to claim 1, further comprising: The crude acetone fraction is combined with the bypass acetone to form a combined stream; Purify the combined stream to produce acetone product; as well as The crude phenol fraction is purified to produce phenol.

3. The method of claim 1, wherein the bypass acetone comprises a first portion of the acetone separated from the product stream at a concentration greater than or equal to 25 vol%.

4. The method according to claim 1, wherein the reflux ratio of the distillation column is less than or equal to 0.

2.

5. The method of claim 1, wherein the distillation feed stream comprises 10 wt% to 20 wt% of cumene or α-methylstyrene or a combination thereof; and The distillation feed stream contains 500 to 2,000 ppm of hydroxyacetone.

6. The method of claim 1, wherein the temperature of the distillation feed stream is 60°C to 120°C.

7. The method of claim 1, wherein the distillation feed stream comprises a weight ratio of 0.8 to 1.7 of cumene to water.

8. The method of claim 1, wherein the crude acetone fraction contains less than or equal to 0.20 wt% phenol.

9. The method of claim 1, wherein the reflux of the distillation column has a temperature of 45°C to 75°C.

10. The method of claim 1, wherein the crude phenol fraction contains less than or equal to 25 ppm of hydroxyacetone; and The crude phenol fraction contains less than or equal to 0.20 wt% α-methylstyrene.

11. The method according to claim 1, wherein the temperature of the crude phenol fraction is 181°C to 190°C.

12. The method of claim 1, wherein the volumetric flow rate of the top stream of the distillation column is reduced by more than or equal to 25% compared to a distillation column having a reflux ratio greater than or equal to 0.50; and Compared to a distillation column with a reflux ratio greater than or equal to 0.50, the volumetric flow rate of the distillation feed stream in the distillation column is increased by greater than or equal to 30%.

13. The method of claim 1, wherein the product stream is a cumene hydroperoxide cracking product stream; and The recycled acetone is then recycled to the cumene hydroperoxide pyrolysis stage.

14. The method of claim 1, further comprising directing the bypass acetone directly to the acetone purification stage.

15. The method of claim 1, wherein the distillation column further comprises 40-55 total balance stages or theoretical plates equivalent to 55-75 total actual plates, and wherein 5-20 of the total balance stages or theoretical plates equivalent to 10-25 actual plates are located in the rectification section above the inlet of the distillation feed stream.

16. The method of claim 1, wherein the distillation column further comprises: The total height "H" measured from the top to the bottom of the distillation column; The first temperature control point is located above the inlet of the distillation feed stream at a height of 15% to 25% of H, wherein the temperature of the first temperature control point is 80°C to 125°C. The second temperature control point is located below the inlet at a height of 25% to 35% of H, wherein the temperature of the second temperature control point is 150°C to 165°C. A third temperature control point is located below the inlet at a height of 40% to 60% of H, wherein the temperature of the third temperature control point is between 150°C and 175°C; and The fourth temperature control point is located below the inlet at a height of 65% to 90% of H, wherein the temperature of the fourth temperature control point is 160°C to 180°C.

17. The method of claim 1, further comprising maintaining a defined temperature profile along a section of the distillation column.

18. The method of claim 17, wherein the determined temperature profile is adjusted by at least one of the following: The composition of the distillation feed stream is adjusted to a weight ratio of cumene to water of 1.1 to 1.6; The temperature of the distillation feed stream is adjusted to 95°C to 105°C; The temperature of the reflux is adjusted to 49°C to 51°C; Adjust the reflux ratio to less than or equal to 0.1; or Adjust the heat applied to the bottom of the distillation column.

19. The method of claim 1, wherein the temperature of the distillation feed stream is 90°C to 110°C; The distillation feed stream comprises a cumene to water weight ratio of 0.8 to 1.7; and further comprises: Maintain a defined temperature profile along a segment of the distillation column, and the temperature of the distillation column's temperature control point is represented by a piecewise polynomial function T(H) over the interval [0; 100], where "T(H)" is a cubic Hermitian interpolation over each subinterval: T(H) = C1H 3 +C2H 2 +C3H+C4, Where "C1", "C2", "C3", and "C4" are the coefficients for each subinterval.

20. The method of claim 1, wherein the distillation column includes a temperature control point and a total equilibrium stage of height "H" measured from the top of the highest equilibrium stage of the distillation column to the bottom of the lowest equilibrium stage of the distillation column, wherein the location of the temperature control point is a percentage of H expressed as "%Hi" and determined by the following equation: %H i = (TT) i / ∑TT, Among them, "(TT)" i " is a balance level and "∑TT" is the total number of balance levels in the tower + 1.

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