Method for producing a fuel additive A method for producing a fuel additive

Abstract

This application relates to a method for producing a fuel additive. The method includes passing a feed stream containing C4 hydrocarbons through a hydrogenation unit to produce a hydrogenated stream; passing the hydrogenated stream through a distillation unit to produce a first stream and a second stream; passing the first stream through a molecular sieve unit to produce an isobutylene stream; passing the isobutylene stream as a raw material for the fuel additive into a hydration unit; and forming the fuel additive in the hydration unit.

Description

[0001] This application is a divisional application of Chinese patent application 201980016878.5 entitled "Method for producing fuel additives", filed on March 18, 2019. Background Technology

[0002] Commercial gasoline is a fuel for internal combustion engines and a refined petroleum product, typically a mixture of hydrocarbons (base gasoline), additives, and blending agents. Additives and blending agents are added to base gasoline to enhance its performance and stability, such as octane boosters.

[0003] When used in high-compression internal combustion engines, gasoline has a tendency to "knock." Knock occurs when the combustion of the air / fuel mixture in the cylinder begins before proper ignition, because one or more air / fuel pockets ignite prematurely outside the envelope of the normal combustion front. Antiknock agents, also known as octane boosters, reduce engine knocking and increase the octane rating of gasoline.

[0004] Hydrocarbon cracking is an important conversion process used in refineries. For example, fluid catalytic cracking (FCC) is widely used to convert high-boiling, high-molecular-weight hydrocarbon fractions from crude oil into more valuable gasoline, olefin gases, and other products. Thermal cracking of naphtha and gas oil is also widely used in the petrochemical industry to produce various olefins and aromatic compounds. For instance, hydrocarbon feedstocks can be mixed with steam and subjected to high temperatures (e.g., 700–900°C) in a steam cracker, where the feedstock group is broken down into various fractions. The effluent from the steam cracker can contain a gaseous mixture of hydrocarbons, such as saturated and unsaturated olefins and aromatic compounds (C1–C35). The effluent can then be separated into individual olefins (e.g., ethylene, propylene, and C4) and pyrolytic gasoline. During these cracking processes, a circulating stream of crude hydrocarbons often forms as a byproduct.

[0005] The presence of isobutene, butadiene, 1-butene, 2-butene, and other components in crude hydrocarbon streams allows for the formation of valuable alcohols and fuel additives. However, converting crude hydrocarbon streams into fuel additive products can often be inefficient and costly. Furthermore, the final product specifications of such alcohols may be suboptimal and may fail to meet market quality requirements. For example, alcohol products may have high levels of impurities, high Reid vapor pressures (e.g., greater than or equal to 13.79 kPa (2.0 psi)), and low octane numbers (e.g., less than or equal to 82 Research Octane Numbers (RON)), all of which contribute to poor product quality. Any improvement in these specifications and / or process efficiency could yield more valuable fuel additive products.

[0006] Therefore, there is a need for an efficient method for producing fuel additives that can utilize crude hydrocarbon streams and produce a final product with low impurities and high performance specifications. Summary of the Invention

[0007] Methods for preparing fuel additives are disclosed in various implementation schemes.

[0008] A method for producing a fuel additive includes passing a feed stream containing C4 hydrocarbons through a hydrogenation unit to produce a hydrogenated stream; passing the hydrogenated stream through a distillation unit to produce a first stream and a second stream; passing the first stream through a molecular sieve unit to produce an isobutylene stream; passing the isobutylene stream as a feedstock for the fuel additive through a hydration unit; and forming the fuel additive in the hydration unit.

[0009] A method for producing fuel additives includes producing hydrogenation products by passing a feed stream containing C4 hydrocarbons through a hydrogenation unit, wherein any butadiene present in the feed stream of ≥90% is converted to 1-butene and / or 2-butene in the hydrogenation unit; passing the hydrogenation products through a distillation unit to produce a first stream containing isobutene and isobutane and a second stream containing n-butane, 1-butene, and 2-butene; producing an isobutene stream with a purity of ≥90% by passing the first stream through a molecular sieve unit with a pore size of 3 to 10; passing the isobutene as a feedstock through a hydration reactor; extracting the 2-butene stream from the distillation unit, passing the 2-butene stream through a second hydrogenation unit to produce a 1-butene stream, and passing the 1-butene stream as a feedstock through a hydration reactor; and extracting a fuel additive product from the hydration reactor, wherein the fuel additive product contains ≥0.5 wt% trimethylpentane.

[0010] These and other features and characteristics are described in more detail below. Attached Figure Description

[0011] The following is a brief description of the accompanying drawings, wherein the same element numbers are the same and these elements are given for the purpose of illustrating the exemplary embodiments disclosed herein and not for the purpose of limiting them.

[0012] Figure 1 This is a schematic diagram showing the sequence of units used in the production of fuel additives. Detailed Implementation

[0013] This paper discloses an efficient method for producing fuel additives that utilizes crude hydrocarbon streams and produces a final product with low impurities and high performance specifications. For example, the method disclosed herein can provide a unique sequence of unit operations that converts crude hydrocarbons into valuable fuel additives, such as alcohol fuel additives. This unique sequence can significantly improve process efficiency, thereby reducing total investment costs. The final fuel additive product can have a high trimethylpentane content, high octane number, and low Reed vapor pressure. For example, the final fuel additive product can have less than or equal to 50 wt% trimethylpentane, such as less than or equal to 25 wt% trimethylpentane, such as greater than or equal to 0.1 wt% trimethylpentane, such as greater than or equal to 0.5 wt% trimethylpentane, such as greater than or equal to 1.0 wt% trimethylpentane, such as 0.1 to 50 wt% trimethylpentane. For example, the final fuel additive product can have an octane number greater than 80, such as greater than 85, such as greater than 90. For example, the final fuel additive product may have a Reid vapor pressure of less than or equal to 100 kPa, such as less than or equal to 75 kPa, such as less than or equal to 55 kPa, such as less than or equal to 50 kPa, such as 25 to 125 kPa, such as 30 to 55 kPa. Any or all of these properties can be associated with high performance and high market value. The methods disclosed herein can also be used to produce byproducts in conjunction with the fuel additive product. For example, ethylene and propylene products can be produced in conjunction with the fuel additive, thereby maximizing the efficiency and productivity of the process.

[0014] The methods disclosed herein can provide a means for producing fuel additives with a minimum number of components. For example, a hydrogenation unit, such as a selective hydrogenation unit, can be included in this method to convert butadiene components into 1-butene and 2-butene, along with the utilization of isobutene in cases where a butadiene unit or MTBE unit is not included in the method. This method can produce fuel additives, such as alcohol fuel additives, from mixed crude hydrocarbon feedstocks, such as C4 hydrocarbons, with minimal capital expenditure and maximum fuel additive production, and even further improved efficiency, from cracking units such as steam cracking units using such units.

[0015] The method disclosed herein provides a novel design for utilizing and converting crude hydrocarbons from the cracking unit's recycled stream as feedstock to maximize the yield of fuel additives. The method includes the use of selective hydrogenation and hydration units to maximize fuel additive production. The method may include the use of molecular sieves to maximize the amount of isobutylene used as feedstock in the hydration unit, which can help maximize the amount of fuel additive produced.

[0016] The method for preparing fuel additives described herein may include passing a feed stream of crude hydrocarbons through a hydrogenation unit, such as a selective hydrogenation unit. The crude C4 hydrocarbon feed stream may contain C4 hydrocarbons. The hydrogenation unit may convert butadiene present in the feed stream into 1-butene and 2-butene to form a hydrogenated stream. The hydrogenated stream is then passed through a distillation unit, which may separate the hydrogenated stream into component hydrocarbons. The reduction of butadiene and the maximization of butene in the streams of this method may increase the desired product specifications of the fuel additive, such as the octane number. A first stream containing isobutane and isobutene may be extracted from the distillation unit and passed through a molecular sieve unit. The molecular sieve unit may separate isobutene. A second stream containing 1-butene and 2-butene may also be extracted from the distillation unit. The isobutene stream and the second feed stream (containing butene) may then be passed through a hydration unit to produce a fuel additive, such as a mixed alcohol fuel additive, such as a C4 alcohol fuel additive. The recycled streams in this process may be used to produce ethylene and propylene as byproducts. Therefore, the method of the present invention can maximize the product quality of fuel additive products, while also producing additional by-products in an efficient manner.

[0017] The methods disclosed herein may include passing a feed stream through an olefin production unit, such as a hydrocarbon cracking unit, or a catalytic and / or steam cracking unit, such that the source of the feed stream may include products of an olefin cracking process and / or an olefin production process. The feed stream may contain hydrocarbons, such as C4 hydrocarbons. Additional hydrocarbons, such as C2 and C3 hydrocarbons, may also be fed into the olefin production unit. The feed stream may then be withdrawn from the olefin production unit as a crude C4 hydrocarbon stream. The feed stream produced by the olefin production unit may include propylene, ethylacetylene, vinylacetylene, propadiene, 1,3-butadiene, 1,2-butadiene, isobutene, cis-2-butene, trans-2-butene, 1-butene, isobutane, n-butane, propylene, or combinations thereof. When withdrawn from the steam cracking unit, the total C4 olefin content in the feed stream may be greater than or equal to 90 wt%, and the feed stream may contain greater than or equal to 15 wt% isobutene. When withdrawn from the fluid catalytic cracking unit, the total C4 olefin content in the process stream can be greater than or equal to 35 wt%, and the feed stream can contain greater than or equal to 30 wt% saturated hydrocarbons. For example, the feed stream can contain a total of greater than or equal to 30 wt% isobutane and n-butane. For example, when withdrawn from the fluid catalytic cracking unit, the total C4 content in the process stream can be 30 to 65 wt%. Isobutene can be present in the feed stream in an amount of 10 to 25 wt%. Saturated hydrocarbons can be present in the feed stream in an amount of 30 to 65 wt%.

[0018] The feed stream can then be passed through a hydrogenation unit, such as a selective hydrogenation unit. For example, the hydrogenation unit could be a selective butadiene hydrogenation unit. The selective butadiene hydrogenation unit can selectively convert butadiene into 1-butene and 2-butene. The feed stream entering the hydrogenation unit may contain less than or equal to 50 wt% butadiene, for example, less than or equal to 30 wt%, or less than or equal to 20 wt%. The hydrogenation unit can convert the butadiene present in the feed stream into 1-butene, cis-2-butene, and trans-2-butene, forming a hydrogenated stream. The conversion rate from butadiene to 1-butene, cis-2-butene, and trans-2-butene can be greater than or equal to 85%, for example, greater than or equal to 90%, for example, greater than or equal to 95%. The hydrogenation unit can also convert propylene, methylacetylene, and propadiene present in the process stream into their respective butenes. Tert-butylcatechol and / or hydrogen can be added to the process stream before passing through the hydrogenation unit.

[0019] The hydrogenation unit may include multiple reactors in series; for example, the unit may include three reactor stages. The first two reactor stages convert butadiene present in the feed stream to 1-butene to 2-butene. The first two reactor stages may contain a hydrogenation catalyst, such as a selective hydrogenation catalyst. For example, the hydrogenation catalyst may contain palladium with an aluminum base. Examples of other catalysts that can be used include, but are not limited to, platinum, rhodium, palladium, ruthenium, cobalt, nickel, copper, or combinations thereof. The catalyst may be the same for the first two reactor stages. Hydrogen may be injected into the feed stream prior to passing through the first reactor stage. In the third reactor stage, the final hydrogenation reaction from diene to mono-olefin can be achieved. In this stage, carbon monoxide may be injected to weaken the catalyst and minimize the isomerization reaction from 1-butene to 2-butene. During normal operation, a recommended carbon monoxide injection rate may be 2 parts per million moles per mole of feed to the third reactor. The operating conditions of the hydrogenation unit are available in Table 1. The first stream can then be withdrawn from the hydrogenation unit. Temperature was measured in degrees Celsius (°C), pressure in kilopascals (kPa) and gauges (psig), and butadiene (BD) content at the outlet of each reactor stage.

[0020]

[0021] The hydrogenated stream can then be passed through a distillation unit, such as a kinetic distillation unit. This unit separates the process stream into component hydrocarbons, forming a first stream and a second stream. The distillation unit can operate under top pressures of 600 kPa to 1000 kPa and reflux temperatures of 35 to 50°C. For example, a first stream containing isobutane and isobutylene can be extracted from the distillation unit and passed through a molecular sieve unit. The first stream may contain greater than or equal to 90 wt% isobutane and / or isobutylene. The molecular sieve unit can separate the isobutylene present in the first stream while filtering out other hydrocarbon components. The molecular sieve may contain zeolite. Zeolite typically has an M... x / n [(AlO2) x (SiO2) y ] The general formula for mH₂O, where x, y, m, and n are positive integers. For example, the molecular formula of zeolite X is Na. 88 Al 88 Si 104 O 384 220H2O. Exemplary zeolites include, but are not limited to, FAU-type zeolites, X, Y, and MFI-type zeolites, such as ZSM-5, siliceous rock-1, zeolite A, ferrite, or combinations thereof. The molecular sieve may be loaded with a π-complex adsorbent. The π-complex adsorbent may include a support material and a compound supported on the support material. The compound may include a metal nitrate. Exemplary metal nitrates may include, but are not limited to, AgNO3, CuNO3, Cu(NO3)2, Fe(NO3)2, or combinations thereof. The support material may include structured silica, alumina, aluminosilicates, titanosilicates, an operating pressure of 345 to 1034 kPa (50 to 150 psig), and an operating temperature of 10 to 150°C. Separation of isobutane and isobutylene is achieved in the molecular sieve via a π-complex adsorbent capable of binding with olefins, while saturated hydrocarbons pass through due to differences in electron affinity. The isobutylene stream can then be extracted from the molecular sieve unit and passed through a hydration unit. The isobutylene stream can have a purity of 90% or higher, for example, 95% or higher, for example, 99% or higher. The pore diameter of the molecular sieve can be from 1 nanometer to 15 nanometers, for example, 4 nanometers to 10 nanometers, and all ranges and values ​​in between. A second stream containing 1-butene and 2-butene can also be drawn from the distillation unit and directly fed into the hydration unit.

[0022] The temperature within the distillation unit can be from 25°C to 100°C, for example, from 45°C to 70°C. The pressure within the distillation unit can be from 500 kPa to 1500 kPa, for example, from 750 kPa to 1200 kPa, for example, from 785 kPa to 1175 kPa.

[0023] The hydration unit hydrates the isobutylene stream and the second stream (containing butene) to produce fuel additives, such as alcohol fuel additives, such as mixed alcohol fuel additives, such as C4 alcohol fuel additives. The second stream entering the hydration unit may contain less than or equal to 5 wt% butadiene, for example, less than or equal to 3 wt%, or for example, less than or equal to 1 wt%. The fuel additive product can be extracted from the hydration unit via the product stream. Water can be supplied to the hydration unit via the water stream. The hydration unit may include an oscillating baffle reactor, a fixed-bed reactor, a membrane integrated reactor, an isothermal multi-tube reactor, or a combination thereof. The hydration unit can convert butene present in the process stream to butanol. For example, 17-99% of the butene present in the second stream can be converted to butanol within the hydration unit. This process stream can be contacted with water and a catalyst within the hydration unit. For example, the catalyst may include phosphoric acid, hypophosphoric acid, sulfonic acid resin, superacid resin, niobium oxide, or a combination thereof. Water and butene may exist in the hydration unit in a molar ratio of 1-15.0 moles of water to 1 mole of butene, for example, 10 moles of water to 1.0 mole of butene. The temperature within the hydration unit may be from 30°C to 250°C, for example, from 100°C to 200°C. The pressure within the hydration unit may be from 500 kPa to 20,000 kPa, for example, from 5,000 kPa to 10,000 kPa, for example, 7,500 kPa.

[0024] Fuel additive products may contain 2-butanol, tert-butanol, C4-dimers, or combinations thereof. For example, C4-dimers may contain diisobutylene, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, or combinations thereof. Fuel additive products may contain greater than or equal to 0.01 wt% of trimethylpentane, for example, greater than or equal to 5.0 wt%, greater than or equal to 10.0 wt%, greater than or equal to 15 wt%, or greater than or equal to 20.0 wt%. Based on the anti-knock index, the octane number of the fuel additive product may be greater than or equal to 80, for example, greater than or equal to 85, for example, greater than or equal to 90, for example, greater than or equal to 93, or for example, greater than or equal to 95.

[0025] Octane rating is a standard metric used to measure the performance of an engine or fuel. A higher octane rating means the fuel can withstand a greater degree of compression before ignition. Fuels with higher octane ratings are typically used in high-performance gasoline engines that require higher compression ratios. Diesel engines may prefer lower octane fuels because they don't compress fuel; instead, they compress only air and then inject fuel into the air heated by compression. Gasoline engines rely on the ignition of the air and fuel, compressed together as a mixture, using a spark plug to ignite it at the end of the compression stroke. As a result, the high compressibility of the fuel is a consideration for gasoline engines.

[0026] The anti-knock index is measured by adding the research octane number (RON) and the engine octane number (MON), i.e., (RON + MON) / 2. RON is determined by running the fuel in a test engine at a variable compression ratio under controlled conditions at 600 rpm and comparing the results to those of mixtures of isooctane and n-heptane. Engine octane is determined by testing a test engine similar to the one used to determine RON, but with a preheated fuel mixture, higher engine speeds, and variable ignition timing at 900 rpm. Depending on the composition, engine octane may be approximately 8 to 12 octane lower than RON. RON can be greater than or equal to 88, for example, greater than or equal to 91, for example, greater than or equal to 93, greater than or equal to 95, greater than or equal to 100. Engine octane can be greater than or equal to 82, for example, greater than or equal to 89, for example, greater than or equal to 90. Higher octane numbers provide a greater amount of energy required to initiate combustion. Fuels with higher octane ratings are less prone to spontaneous combustion and, in the absence of spontaneous combustion, can withstand higher temperature rises during the compression stroke of an internal combustion engine.

[0027] Reed vapor pressure is used to measure the volatility of gasoline and is defined as the absolute vapor pressure exerted by a liquid at 37.8°C, as determined by ASTM D-323. This method measures the vapor pressure of gasoline-volatile crude oil and other volatile petroleum products, excluding liquefied petroleum gas. Reed vapor pressure is measured in kilopascals (kPa) and represents the relative pressure to atmospheric pressure, as ASTM D-323 measures the gauge pressure of samples in a non-vacuum chamber. Higher levels of vaporization are desired for winter starts and operation, while lower levels are preferred to avoid vapor lock during hot summer months. The presence of vapor in the fuel lines prevents fuel pumping, and winter starts are difficult if the liquid gasoline in the combustion chamber has not yet evaporated. Therefore, this means that oil producers adjust Reed vapor pressure seasonally to maintain the reliability of gasoline engines.

[0028] The Reid vapor pressure of fuel additive products can be less than or equal to 55 kPa, for example, from 5 kPa to 55 kPa, or from 5 kPa to 40 kPa. The Reid vapor pressure may vary under winter and summer conditions, with higher pressures in winter and lower pressures in summer.

[0029] Alternatively, a 2-butene stream can be drawn from the distillation unit and passed through a second hydrogenation unit. The 2-butene stream may contain n-butane, 1-butene, and 2-butene. The second hydrogenation unit can convert the 2-butene present in the 2-butene stream to 1-butene. Operating conditions for the second hydrogenation unit may include a pressure of 34 kPa to 105 kPa (5-15 bar) and a temperature of 180 to 300°C. The 1-butene stream can then be drawn from the second hydrogenation unit and recycled back to the distillation unit. The 1-butene stream may contain 1-butene and n-butane. A portion of the 1-butene stream may optionally pass through a separation unit. The temperature within the distillation unit may be 25°C to 100°C, for example, 45°C to 70°C. The pressure within the distillation unit may be 500 kPa to 1500 kPa, for example, 750 kPa to 1200 kPa, for example, 785 kPa to 1175 kPa. The separation unit can separate and isolate 1-butene. The separated 1-butene stream can then be extracted from the separation unit and passed through the hydration unit.

[0030] A recycle stream, such as a hydrocarbon recycle stream, can be drawn from the hydration unit and recycled back to the initial feed stream and / or an olefin production unit, such as a steam cracker unit. The recycle stream may contain butene, isobutane, n-butane, isobutene, or combinations thereof. Optionally, the recycle stream may pass through a recycle hydrogenation unit before returning to the feed stream. The recycle hydrogenation unit can convert 1-butene and 2-butene present in the recycle stream to n-butane and isobutane. For example, any butene present in the hydrocarbon recycle stream at a concentration of 90% or higher can be converted to butane within the recycle hydrogenation unit.

[0031] Additional recycled streams can be extracted from this process and used to produce ethylene and propylene as byproducts. For example, a n-butane stream can be extracted from the distillation and / or separation unit. An isobutane stream can also be extracted from the molecular sieve unit. These additional recycled streams can then be used to produce the byproducts ethylene and propylene. For example, the metathesis unit can convert n-butene and ethylene into polymer-grade propylene through metathesis.

[0032] A more complete understanding of the components, processes, and apparatuses 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 indicate the relative size and dimensions of the apparatus or its components and / or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for clarity, these terms are only intended to denote specific structures selected for illustration in the drawings and are not intended to define or limit the scope of this disclosure. In the following drawings and description, it should be understood that the same numerical designations refer to components having the same function.

[0033] Now for reference Figure 1 This simplified schematic diagram illustrates unit sequence 10 used in a method for producing fuel additives. Sequence 10 may include passing a feedstock 12 containing hydrocarbons through a hydrocarbon cracking unit 14. For example, hydrocarbon cracking unit 14 may be a steam cracking and / or catalytic cracking unit.

[0034] Then, feed stream 16 can be withdrawn from cracking unit 14. Feed stream 16 may contain crude hydrocarbons, such as C4 hydrocarbons. Feed stream 16 can then be passed through hydrogenation unit 18, such as a selective hydrogenation unit. Hydrogenation unit 18 may be a selective butadiene hydrogenation unit and may include multiple reactors in series. This hydrogenation unit 18 can convert the butadiene present in feed stream 16 into 1-butene and 2-butene.

[0035] Then, the hydrogenated stream 24 can be drawn from the hydrogenation unit 18 and passed through the distillation unit 26. The distillation unit 26 can separate the hydrogenated stream 24 into component hydrocarbons. A first stream 28 containing isobutane and isobutene can be drawn from the distillation unit 26 and passed through the molecular sieve unit 30. The molecular sieve unit 30 can separate the isobutene present in the first stream 28 while filtering out other hydrocarbon components. An isobutene stream 32 can then be drawn from the molecular sieve unit 30 and passed through the hydration unit 42. A second stream 35 containing 1-butene and 2-butene can also be drawn from the distillation unit 26 and directly introduced into the hydration unit 42.

[0036] Hydration unit 42 can hydrate isobutylene stream 32 and second stream 35 (containing butene) to produce fuel additive. Fuel additive product 46 can be extracted from hydration unit 42. Water can be fed into hydration unit via stream 44.

[0037] Alternatively, a 2-butene stream 34 can be drawn from distillation unit 26 and passed through a second hydrogenation unit 36. The second hydrogenation unit 36 ​​can convert the 2-butene present in stream 34 into 1-butene. A 1-butene stream 38 can then be drawn from the second hydrogenation unit 36 ​​and recycled back to distillation unit 26. A portion of the 1-butene stream can optionally pass through stream 40 to separation unit 20. Separation unit 20 can separate and isolate 1-butene. The separated 1-butene stream 22 can then be drawn from separation unit 20 and passed through hydration unit 42.

[0038] Hydrocarbon recirculation stream 48 can be drawn from hydration unit 42 and recycled to feed stream 12 and / or cracking unit 14. Recirculation stream 48 can pass through hydrogenation unit 50 before returning to feed stream 12.

[0039] The methods disclosed in this paper include at least the following aspects: Aspect 1: A method for producing a fuel additive, comprising: passing a feed stream containing C4 hydrocarbons through a hydrogenation unit to produce a hydrogenated stream; passing the hydrogenated stream through a distillation unit to produce a first stream and a second stream; passing the first stream through a molecular sieve unit to produce an isobutylene stream; passing the isobutylene stream as a raw material for the fuel additive through a hydration unit; and forming the fuel additive in the hydration unit.

[0040] Aspect 2: According to the method of aspect 1, the feed stream comprises propylene, ethyl acetylene, vinyl acetylene, propadiene, 1,3-butadiene, 1,2-butadiene, isobutene, cis-2-butene, trans-2-butene, 1-butene, isobutane, n-butane, propylene, or combinations thereof.

[0041] Aspect 3: The method according to any one of the preceding aspects, wherein the first stream comprises isobutane and isobutene.

[0042] Aspect 4: The method according to any one of the preceding aspects, wherein the second stream comprises 1-butene and 2-butene.

[0043] Aspect 5: The method according to any one of the preceding aspects, wherein greater than or equal to 85 wt%, preferably greater than or equal to 90 wt%, more preferably, greater than or equal to 95 wt% of any butadiene present in the feed stream is converted into 1-butene and / or 2-butene within the hydrogenation unit.

[0044] Aspect 6: The method according to any one of the preceding aspects further includes passing a stream of water through the hydration unit.

[0045] Aspect 7: The method according to any one of the preceding aspects further includes adding tert-butylcatechol and / or hydrogen to the feed stream prior to passing through the hydrogenation unit.

[0046] Aspect 8: The method according to any one of the preceding aspects further includes extracting isobutylene product from the isobutylene stream, wherein the purity of the isobutylene product is greater than or equal to 90%, preferably greater than or equal to 95%, more preferably greater than or equal to 99%.

[0047] Aspect 9: The method according to any one of the preceding aspects further includes extracting the n-butane stream from the distillation unit and recycling the n-butane stream back to the feed stream.

[0048] Aspect 10: The method according to any one of the preceding aspects further includes extracting the isobutane stream from the molecular sieve unit and recycling the isobutane stream back to the feed stream.

[0049] Aspect 11: The method according to aspect 10 further includes passing the isobutane stream through a propylene unit and extracting propylene product from the propylene unit.

[0050] Aspect 12: The method according to any one of the preceding aspects further includes extracting a 2-butene stream from the distillation unit, passing the 2-butene stream through a second hydrogenation unit to produce a 1-butene stream, and recycling the 1-butene stream back to the distillation unit.

[0051] Aspect 13: The method according to aspect 12 further includes passing at least a portion of the 1-butene stream through the separation unit and through the hydration unit.

[0052] Aspect 14: The method according to any one of the preceding aspects, wherein the hydration unit comprises an oscillating baffle reactor, a fixed bed reactor, a membrane integrated reactor, an isothermal multi-tube reactor, or a combination thereof.

[0053] Aspect 15: The method according to any one of the preceding aspects, wherein any butene present in the second stream of greater than or equal to 0.01% is converted into butanol within the hydration unit.

[0054] Aspect 16: The method according to any one of the preceding aspects further includes extracting a fuel additive product from the hydration unit, wherein the fuel additive product comprises 2-butanol, tert-butanol, diisobutylene, or a combination thereof.

[0055] Aspect 17: The method according to aspect 16, wherein the fuel additive product comprises greater than or equal to 0.01% trimethylpentane.

[0056] Aspect 18: The method according to aspect 16, wherein the octane number of the fuel additive product is greater than or equal to 85 according to the anti-knock index.

[0057] Aspect 19: According to the method of aspect 16, the Reid vapor pressure of the fuel additive product is less than or equal to 75 kPa, preferably less than or equal to 65 kPa, preferably less than or equal to 60 kPa, and preferably less than or equal to 55 kPa.

[0058] Aspect 20: A method for producing a fuel additive, comprising: producing a hydrogenation product by passing a feed stream comprising C4 hydrocarbons through a hydrogenation unit, wherein 90% or more of any butadiene present in the feed stream is converted to 1-butene and / or 2-butene in the hydrogenation unit; passing the hydrogenation product through a distillation unit to produce a first stream comprising isobutene and isobutane and a second stream comprising n-butane, 1-butene, and 2-butene; producing an isobutene stream having a purity of 90% or more by passing the first stream through a molecular sieve unit with a pore size of 3 to 10; passing the isobutene as a feedstock through a hydration reactor; extracting a 2-butene stream from the distillation unit; passing the 2-butene stream through a second hydrogenation unit to produce a 1-butene stream; and passing the 1-butene stream as a feedstock through the hydration reactor; and extracting a fuel additive product from the hydration reactor, wherein the fuel additive product comprises 0.5 wt% or more of trimethylpentane.

[0059] Generally, the present invention may alternatively include, consist of, or substantially consist of any suitable components disclosed herein. The present invention may additionally or alternatively be formulated free from or substantially free from any components, materials, ingredients, adjuvants, or substances used in prior art compositions or otherwise not essential for achieving the function and / or purpose of the present invention. Endpoints to all ranges for the same component or property are inclusive and independently combinable (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 or more specific group, in addition to a broader range, is not a waiver of a broader or larger group. “Combination” includes blends, mixtures, alloys, reaction products, etc. Furthermore, the terms “first,” “second,” etc., herein do not indicate any order, quantity, or importance, but are used to indicate one element as distinct from another. The terms “a,” “an,” and “the” used herein do not indicate a limitation of quantity and should be interpreted to cover both the singular and the plural unless otherwise stated herein or the context clearly contradicts it. “Or” means “and / or.” As used herein, the suffix “(s)” is intended to include both the singular and the plural of the term it modifies, thereby including one or more of that term (e.g., film(s)) includes one or more films). References throughout the specification to “one embodiment,” “another embodiment,” “an embodiment,” etc., mean 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 elements described in the various embodiments can be combined in any suitable manner.

[0060] The modifier “approximately” used with quantity includes the value and has the meaning indicated by the context (e.g., including the degree of error associated with a particular quantity measurement). The symbol “ +"10%" indicates that the indicated measurement value can be an amount from -10% of the value to +10% of the value. Unless otherwise stated, the terms "before," "after," "bottom," and / or "top" as used herein are merely for ease of description and are not limited to any particular location or spatial orientation. "Optional" or "optionally" means that an event or situation subsequently described may or may not occur, and the description includes instances in which the event occurs and instances in which the event does not occur. 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 invention pertains. "Combination" includes blends, mixtures, alloys, reaction products, etc. In a list of alternative substances, "combination thereof" means that the combination may include at least one element from the list with one or more unnamed similar elements. Additionally, "at least one" means that the list includes each element individually, as well as combinations of two or more elements from the list, and combinations of at least one element from the list with unnamed similar elements.

[0061] 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 in this application shall take precedence over the conflicting terminology in the incorporated references.

[0062] Although specific embodiments are described, the applicant or a person skilled in the art may conceive of alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or may not currently be foreseen. Therefore, the appended claims, which are filed and may be modified thereto, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. A method for producing fuel additives, comprising: A feed stream containing C4 hydrocarbons is passed through a hydrogenation unit to produce a hydrogenated stream, wherein the hydrogenation unit comprises multiple reactors connected in series, wherein the hydrogenation temperature is 40-80°C. o The reactor is operated at a temperature in the range of C and a pressure in the range of 140-400 psig, wherein greater than or equal to 85 wt% of any butadiene present in the feed stream is converted into 1-butene and / or 2-butene within the hydrogenation unit. The hydrogenated stream is passed through a distillation unit to produce a first stream and a second stream; An isobutylene stream with a purity greater than or equal to 90% is produced by passing the first stream through a molecular sieve unit. The isobutylene stream is then fed into the hydration unit as a raw material for the fuel additive. and The fuel additive is formed in the hydration unit.

2. The method according to claim 1, wherein the feed stream comprises at least one of propylene, ethyl acetylene, vinyl acetylene, propadiene, 1,3-butadiene, 1,2-butadiene, isobutene, cis-2-butene, trans-2-butene, 1-butene, isobutane, n-butane, or propylene.

3. The method of claim 1, wherein the first stream comprises isobutane and isobutene, and wherein the second stream comprises 1-butene and 2-butene.

4. The method of claim 1, further comprising adding tert-butylcatechol and / or hydrogen to the feed stream prior to passing through the hydrogenation unit, causing the water stream to pass through the hydration unit, or both.

5. The method of claim 1, further comprising extracting a n-butane stream from the distillation unit and recycling the n-butane stream back to the feed stream.

6. The method of claim 1, further comprising extracting an isobutane stream from the molecular sieve unit, and a) recycling the isobutane stream back to the feed stream, b) passing the isobutane stream through the propylene unit and extracting propylene product from the propylene unit, or both a) and b).

7. The method of claim 1, further comprising extracting a 2-butene stream from the distillation unit, passing the 2-butene stream through a second hydrogenation unit to produce a 1-butene stream, and recycling the 1-butene stream back to the distillation unit.

8. The method of claim 7, further comprising passing at least a portion of the 1-butene stream through a separation unit and through the hydration unit.

9. The method according to claim 1, wherein the hydration unit comprises at least one of an oscillating baffle reactor, a fixed bed reactor, a membrane integrated reactor, or an isothermal multi-tube reactor.

10. The method of claim 1, wherein any butene present in the second stream at a concentration greater than or equal to 0.01% is converted to butanol within the hydration unit.

11. The method of claim 1, further comprising extracting a fuel additive product from the hydration unit, wherein the fuel additive product comprises at least one of 2-butanol, tert-butanol, or diisobutylene.

12. The method of claim 11, wherein the fuel additive product comprises greater than or equal to 0.01% trimethylpentane; the octane number of the fuel additive product is greater than or equal to 85 according to the anti-knock index; or the reed vapor pressure of the fuel additive product is less than or equal to 75 kPa.

13. The method according to claim 1, Any butadiene present in the feed stream of 90% or more is converted into 1-butene and / or 2-butene in the hydrogenation unit; The first stream comprises isobutene and isobutane, and the second stream comprises n-butane, 1-butene, and 2-butene; Molecular sieves have pore sizes ranging from 3 to 10, and The fuel additive product contains ≥0.5 wt% trimethylpentane.

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