Isobutane oxidation method and system

Abstract

Disclosed in the present invention are an isobutane oxidation method and system. The method comprises: 1) mixing an isobutane-rich gas stream with a nitrogen-rich gas stream to prepare a first carrier gas for use; 2) uniformly mixing oxygen with the first carrier gas in a proportion to obtain an oxygen-containing gas stream having an oxygen concentration of 1-10 vol%; and 3) introducing the oxygen-containing gas stream into the bottom of a reactor to react with liquid-phase isobutane fed into the reactor, thereby producing tert-butyl hydroperoxide. The present invention ensures the operability and safety of the isobutane oxidation reaction by providing a bi-component carrier gas of isobutane and nitrogen in different proportions and by introducing oxygen having a safe concentration into the reactor. Moreover, in the present invention, the nitrogen circulation is separately arranged in the carrier gas, such that only one compressor is required for a system comprising multiple reactors. Furthermore, the liquid-phase material in multiple oxidation reactors overflows to the next stage due to gravity, which eliminates interstage transfer pumps and reduces equipment investment.

Description

A method and system for isobutane oxidation Technical Field

[0001] This invention relates to the field of chemical engineering, and in particular to an isobutane oxidation method for improving the operability and safety of liquid-phase oxidation reactions. This method ensures the operability and safety of the isobutane oxidation reaction by setting a two-component carrier gas with different proportions of isobutane and nitrogen, and by preparing a safe concentration of oxygen to be introduced into the reactor. Background Technology

[0002] Tert-Butyl hydroperoxide (TBHP) is an organic peroxide widely used as an oxidant and initiator for free radical reactions. It is also a common oxygen source for the co-oxidation process of propylene to produce propylene oxide. Large-scale industrial production of TBHP typically uses isobutane as a raw material and molecular oxygen as the oxidant.

[0003] Currently known methods for producing tert-butyl hydrogen peroxide from isobutane via liquid-phase oxidation are based on the non-catalytic liquid-phase oxidation process for preparing tert-butyl hydrogen peroxide and tert-butanol disclosed in patents US2845461 and US3478108. American companies ARCO and Texaco have also disclosed methods for the non-catalytic liquid-phase oxidation of isobutane with molecular oxygen to prepare tert-butanol and tert-butyl hydrogen peroxide in patents US5243084 and US5399777. Typical reaction conditions for isobutane liquid-phase oxidation are a reaction temperature of 100–150 °C and a reaction pressure of 2.0–4.8 MPa, with direct oxidation of liquid-phase isobutane by molecular oxygen over 2–5 hours, achieving an isobutane conversion of 36–46%, and selectivities of 48.0–53.4% ​​for TBHP and 40.2–47.0% for TBA.

[0004] In addition to the oxidation method under liquid-phase conditions of isobutane, Shell, a European company, discloses a method for producing tert-butyl hydrogen peroxide (TBHP) under supercritical conditions in patent US4404406. This method operates under supercritical conditions at a temperature above the critical temperature of the mixture (>140°C) and at a pressure above the critical pressure of the mixture (>4.8 MPa), which can significantly improve the production efficiency of TBHP per unit time and unit reactor volume.

[0005] Several domestic patents have also been published for improving isobutane oxidation methods. Sinopec's patent CN201110113828.4 uses ozone as an oxidant, eliminating the need for a catalyst, simplifying the isobutane oxidation process, increasing isobutane conversion, reducing costs, and making it suitable for industrialization. Many patents have also been published that use catalysts to improve isobutane conversion and tert-butyl hydroperoxide selectivity. For example, Yuxin Chemical's patent CN201710467464.7 uses an NHPI catalyst and a β-cyclodextrin modifier to improve conversion and selectivity, while being environmentally friendly. Sun Yat-sen University Huizhou Research Institute's patent CN201410449806.9 uses a metalloporphyrin compound catalyst, achieving mild reaction conditions and high selectivity.

[0006] In summary, most current research in the field of isobutane oxidation to tert-butyl hydrogen peroxide and tert-butanol focuses on optimizing process conditions, improving catalysts, and increasing production efficiency. Some studies have also investigated the reactor and process safety of the liquid-phase isobutane-molecular oxygen reaction.

[0007] Arco's patent US5149885 discloses a process for the liquid-phase oxidation of isobutane to prepare TBHP, which uses a spherical reactor and a reaction temperature of 137°C. The process involves liquid-phase circulation for heat removal, with oxygen mixed with the circulating liquid before entering the reactor. This process is unfavorable for reactor level control, easily leading to either full tank or below the circulation output line. Furthermore, the circulating material is prone to cavitation after being transported by the circulation pump. In addition, the fabrication of large spherical reactors is also difficult.

[0008] Texco's patent US5243083 discloses a process for the liquid-phase oxidation of isobutane to produce TBHP. This process uses an internally circulating tower reactor. Oxygen is mixed with the gaseous circulating material and enters the middle of the reactor. During the upward flow, isobutane reacts with oxygen to produce TBHP. After gas-liquid separation at the top, the liquid material and fresh isobutane flow downwards from the outer ring of the reactor, forming a thermosiphon circulation. This process places high demands on equipment, as the direct mixing of liquid isobutane and oxygen within the reactor can easily exceed the explosion limits.

[0009] Shell's patent US4408081 discloses a process for preparing TBHP in which isobutane and oxygen operate in a supercritical state at a reaction temperature of 145–165°C and a reaction pressure of 5.5–10.3 MPa. This process employs a multi-stage series reaction, improving the selectivity of tert-butyl hydroperoxide by controlling the oxygen concentration in the reaction mixture below 0.1%M. This process is not suitable for operation under high oxygen concentrations because it cannot ensure complete oxygen reaction within the reactor. Increased incompletely reacted oxygen will prevent the preset operating conditions from maintaining the reactants in a supercritical state, causing the material to fall into the explosive range during the transition to a gas-liquid phase.

[0010] Patent CN116099483 from Shandong Tianhong Chemical discloses a tower reactor and production system for the oxidation of isobutane to prepare tert-butyl hydrogen peroxide. This system employs a tower structure, eliminating the need for transfer pumps between reactors. A nitrogen regulating component adjusts the amount of nitrogen introduced into the reaction space to remove heat from the reaction, preventing excessively vigorous material reaction and resulting in overheating. However, controlling the concentration of gaseous oxygen between the trays within this tower reactor makes safe production difficult.

[0011] Patent CN109928863B from Beijing Shuimu Binhua Technology Co., Ltd. discloses a reaction apparatus and method for preparing tert-butanol and tert-butyl hydrogen peroxide from isobutane and oxygen. Gaseous oxygen is dissolved in liquid reactants in a static mixer to obtain an oxygen-containing liquid material, which is then fed into a reactor for reaction. The reactor operates with no gaseous space above it (full liquid level operation), improving reaction safety. Summary of the Invention

[0012] The main objective of this application is to provide an isobutane oxidation method and system, which ensures the operability and safety of the isobutane oxidation reaction by setting a two-component carrier gas with different proportions of isobutane and nitrogen, and by preparing a safe concentration of oxygen to be introduced into the reactor.

[0013] To achieve the above objectives, in a first aspect, this application provides a method for isobutane oxidation, comprising the following steps:

[0014] S1, Carrier gas configuration: The isobutane-rich gas stream and the nitrogen-rich gas stream are mixed evenly in a certain proportion to form the first carrier gas;

[0015] S2. Preparation of reaction carrier gas: Oxygen is mixed with the first carrier gas in a uniform ratio to form the second carrier gas, wherein the oxygen concentration is 1-10 vol%.

[0016] S3. Oxidation reaction: The second carrier gas is introduced into the bottom of the oxidation reactor to react with the liquid isobutane in the oxidation reactor to generate tert-butyl hydrogen peroxide. The reaction temperature of the oxidation reactor is controlled by adjusting the nitrogen ratio in the first carrier gas, and the oxidation rate and tail oxygen concentration are controlled by adjusting the oxygen ratio in the second carrier gas.

[0017] Optionally, it also includes S4, tail gas and condensate circulation. The tail gas flowing out from the top of the oxidation reactor is condensed and compressed in sequence. The gas phase tail gas is used as the first carrier gas as a nitrogen-rich gas stream. A portion of the condensed liquid phase tail gas is vaporized and used as the first carrier gas as an isobutane-rich gas stream. The other portion is heated and enters the oxidation reactor as a reaction feedstock.

[0018] Optionally, the tail gas flowing out from the top of the oxidation reactor is condensed in stages, with 1 to 5 condensation stages, and the high-temperature condensate with a temperature greater than 110°C is returned to the oxidation reactor as a reaction feedstock.

[0019] Optionally, the tail gas flowing out from the top of the oxidation reactor is condensed and compressed after exchanging heat with liquid isobutane.

[0020] Optionally, in step S1, the nitrogen-rich gas stream has a nitrogen concentration >80 vol% and an oxygen concentration <1 vol%; the isobutane-rich gas stream has an isobutane concentration >70 vol%.

[0021] Optionally, the nitrogen content in the first carrier gas is 10–95 vol%.

[0022] Optionally, in step S3, the temperature of the oxidation reactor is maintained at 120-150℃, the reaction pressure is 2.8-4.5MPa, the oxidation reaction zone is set at 1-10 levels, and the reaction temperature decreases step by step.

[0023] To achieve the above objectives, in a second aspect, a preparation system for isobutane oxidation includes an oxidation reactor group, an oxidation tail gas condenser connected to the tail gas outlet of the oxidation reactor group, an oxidation tail gas separator connected to the oxidation tail gas condenser, an oxidation tail gas recirculation compressor connected to the gas phase outlet of the oxidation tail gas separator, a tail gas condensate booster pump connected to the liquid phase outlet of the oxidation tail gas separator, and an oxidation feed heating vaporizer connected to the tail gas condensate booster pump. A liquid isobutane material inlet is connected to the oxidation feed heating vaporizer. The gas flowing out of the gas phase outlet of the oxidation feed heating vaporizer is mixed proportionally with the gas flowing out of the oxidation tail gas recirculation compressor to form a first carrier gas. The system also includes a static mixer and an oxygen supply device. The oxygen generated by the oxygen supply device is mixed with the first carrier gas in the static mixer to form a second carrier gas. The second carrier gas is connected to the oxidation reactor group, and the liquid phase outlet of the oxidation feed heating vaporizer is connected to the oxidation reactor group.

[0024] Optionally, it also includes an oxidation tail gas heat exchanger disposed between the oxidation reactor group and the oxidation tail gas condenser, wherein the tail gas discharged from the oxidation reactor group exchanges heat with the liquid isobutane material and the tail gas condensate discharged by the tail gas condensate booster pump through the oxidation tail gas heat exchanger.

[0025] Optionally, it also includes a high-temperature condensate tank disposed between the oxidation tail gas heat exchanger and the oxidation tail gas condenser, wherein the gas phase outlet of the high-temperature condensate tank is connected to the oxidation tail gas condenser, and the liquid phase outlet of the high-temperature condensate tank is connected to the oxidation reactor group through a high-temperature condensate pump.

[0026] The isobutane oxidation method and system provided by this invention have the following advantages compared with the prior art:

[0027] The oxygen-carrying gas stream incorporates gaseous isobutane. The gas stream entering the reactor mainly consists of three components: oxygen, nitrogen, and isobutane. Since the isobutane vapor is identical to the liquid phase material within the reactor, the circulation of the isobutane vapor does not cause vaporization and endothermic reactions in the liquid phase, thus ensuring a stable reaction temperature. Furthermore, adjusting the tail oxygen concentration does not require nitrogen replenishment; instead, the oxygen concentration in the inlet gas can be directly adjusted, completely avoiding the heat balance problem during the circulation of oxygen and nitrogen. Both the oxygen and nitrogen contents in the gas stream entering the reactor can be flexibly adjusted. Adjusting the oxygen content controls the oxidation rate and tail oxygen concentration, while adjusting the nitrogen content controls the reaction temperature, thus balancing the safety and operability of the oxidation reaction.

[0028] In this invention, the oxygen is pre-prepared with the carrier gas outside the reactor. The oxygen content in the prepared gas stream is strictly controlled, determined by the upper explosive limit of the materials inside the reactor (organic substances such as isobutane / tert-butanol). However, a suitable safety margin is usually left at the operating point. This invention requires the oxygen content in the gas stream entering the reactor to be <= 8%. This is based on intrinsic safety considerations. Even in the event of misoperation (such as the reaction temperature being too low, resulting in insufficient oxygen reaction), it can ensure that the tail oxygen concentration in the reactor does not exceed the limit, preventing the tail gas from falling into the explosive range.

[0029] The number of isobutane oxidation reactors typically exceeds one. When multiple reactors are used, the operating temperatures and TBHP concentrations within the reactors differ, resulting in varying gas phase compositions exiting from each reactor. Directly mixing these components and feeding them into the same compressor's booster cycle would lead to identical inlet gas compositions across multiple reactors, failing to accommodate the varying operating temperatures and compositional changes of each reactor. Consequently, traditional processes require a dedicated compressor for each reactor, resulting in high equipment investment costs. The carrier gas in this invention is prepared by combining nitrogen-rich and isobutane-rich gas streams according to the operating temperatures of each reactor. Even if the exhaust gas compositions differ across reactors, after mixing and condensation, they will all separate into a nitrogen-rich gas stream and an isobutane-rich liquid phase. A single exhaust gas compressor can compress the nitrogen-rich gas stream, and then, based on the needs of each reactor, the nitrogen-rich and isobutane-rich gas streams are mixed in proportion to prepare the carrier gas required by each reactor. Therefore, this invention significantly reduces compressor investment costs when using multiple reactors.

[0030] The liquid phase material from multiple oxidation reactors overflows to the next stage by gravity, eliminating the need for interstage transfer pumps and reducing equipment investment. Attached Figure Description

[0031] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0032] Figure 1 is a schematic diagram of the reaction process according to a preferred embodiment of the present invention.

[0033] Figure 2 is a schematic diagram of the reaction process shown in a preferred energy-saving scheme of the present invention.

[0034] Among them: 101, First oxidation reactor; 102, Second oxidation reactor; 103, Third oxidation reactor; 104, Oxidation tail gas condenser; 105, Oxidation tail gas separator; 106, Oxidation tail gas recirculation compressor; 107, Tail gas condensate booster pump; 108, Oxidation feed heating vaporizer; 109, Oxidation tail gas heat exchanger; 110, High-temperature condensate tank; 111, High-temperature condensate pump; 112a~112c, Static mixer; S1~S11 logistics numbers. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0038] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain circumstances to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0039] In addition, the term "multiple" should mean two or more.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Example 1:

[0042] An isobutane oxidation method includes the following steps:

[0043] S1, Carrier gas configuration: The isobutane-rich gas stream and the nitrogen-rich gas stream are mixed evenly in a certain proportion to form the first carrier gas;

[0044] S2. Preparation of reaction carrier gas: Oxygen is mixed with the first carrier gas in a uniform ratio to form the second carrier gas, wherein the oxygen concentration is 1-10 vol%.

[0045] S3. Oxidation reaction: The second carrier gas is introduced into the bottom of the oxidation reactor to react with the liquid isobutane in the oxidation reactor to generate tert-butyl hydrogen peroxide. The reaction temperature of the oxidation reactor is controlled by adjusting the nitrogen ratio in the first carrier gas, and the oxidation rate and tail oxygen concentration are controlled by adjusting the oxygen ratio in the second carrier gas.

[0046] In step S1, the nitrogen-rich gas stream has a nitrogen concentration >80 vol% and an oxygen concentration <1 vol%. In the isobutane-rich gas stream, the isobutane concentration >70 vol%. The nitrogen content in the first carrier gas is 10–95 vol%. In step S3, the temperature of the oxidation reactor is maintained at 120–150 °C, the reaction pressure is 2.8–4.5 MPa, the oxidation reaction zone is set at 1–10 levels, and the reaction temperature decreases step by step.

[0047] Preferably, the process further includes step S4, tail gas and condensate circulation. The tail gas flowing out from the top of the oxidation reactor is condensed and compressed in sequence. The gas phase tail gas is used as a nitrogen-rich gas stream for the first carrier gas configuration. A portion of the condensed liquid phase tail gas is vaporized and used as an isobutane-rich gas stream for the first carrier gas configuration. The other portion is heated and enters the oxidation reactor as a reaction raw material.

[0048] Preferably, the tail gas flowing out from the top of the oxidation reactor is condensed in stages, with 1 to 5 condensation stages, and the high-temperature condensate with a temperature greater than 110°C is returned to the oxidation reactor as a reaction feedstock.

[0049] Preferably, the exhaust gas flowing out from the top of the oxidation reactor exchanges heat with liquid isobutane and then is condensed and compressed.

[0050] Explanation of the principle:

[0051] For the liquid-phase oxidation reaction of isobutane, oxygen enters the reactor and reacts with the liquid isobutane to produce tert-butyl hydrogen peroxide, releasing heat of reaction. Introducing nitrogen into the reactor causes some of the liquid isobutane to vaporize and absorb heat, carrying away the heat of reaction. This is the basis for controlling the temperature of the isobutane liquid-phase oxidation reaction. However, in practice, it is difficult to achieve normal operation of the isobutane liquid-phase oxidation reaction using the conventional two-component gas flow scheme of oxygen + nitrogen. Because isobutane has a low boiling point (-10.5℃ at normal pressure), the equilibrium partial pressure of nitrogen (N2) is relatively high. For a material system with isobutane / tert-butanol = 0.7 / 0.3wt / wt, after reaching equilibrium, adding 1 mol of nitrogen to the liquid phase at 3.7 MPa and 135℃ will cause ~4 mol of liquid material to vaporize, carrying away 44.4 kJ of heat. To balance this heat, the heat of reaction from the oxidation of isobutane needs to compensate. The heat of reaction per unit reaction for the production of tert-butyl hydrogen peroxide from the reaction of isobutane with oxygen is 108.4 kJ / mol. To balance the heat removed during the oxidation reaction, 0.41 mol of oxygen is required in the reactor. Assuming an oxygen utilization rate of 95%, the oxygen content in the oxygen-containing gas introduced into the oxidation reactor is 30%, which poses a considerable safety risk for the liquid-phase oxidation of isobutane, especially when the oxygen utilization rate is low. This could directly cause the gas phase in the oxidation reactor to fall into the explosion range. Furthermore, controlling the oxygen content in both components is extremely difficult. When the isobutane oxidation reaction temperature is slightly lower and the oxygen utilization rate is low, the oxygen concentration in the gas phase of the reactor will increase. To control the further increase in oxygen concentration, it is necessary to reduce the oxygen injection rate or increase the nitrogen injection rate. However, as the above analysis shows, both methods will further decrease the reaction temperature and further increase the tail oxygen level, creating a vicious cycle of continuously decreasing reaction temperature, making normal operation impossible.

[0052] In this method, gaseous isobutane is introduced into the oxygen-carrying gas stream. The gas stream entering the reactor mainly consists of three components: oxygen, nitrogen, and isobutane. Since the isobutane vapor is the same as the liquid phase material in the reactor, the circulation of isobutane vapor does not cause vaporization and heat absorption in the liquid phase material, thus ensuring the reaction temperature. Furthermore, the tail oxygen concentration does not require nitrogen supplementation; instead, the oxygen concentration in the inlet gas can be directly adjusted, completely avoiding the heat balance problem during the circulation of oxygen and nitrogen. The oxygen and nitrogen contents in the gas stream entering the reactor can be flexibly adjusted. Adjusting the oxygen content controls the oxidation rate and tail oxygen concentration, while adjusting the nitrogen content controls the reaction temperature, thus balancing the safety and operability of the oxidation reaction.

[0053] The following example uses the isobutane oxidation reaction process with an oxygen consumption of 10 t / h.

[0054] Carrier gas preparation: Nitrogen gas and isobutane-rich gas are mixed to prepare a carrier gas with a flow rate of 5937 kmol / h.

[0055] Preparation of oxygen-containing gas: Inject oxygen into the carrier gas at a rate of 312.5 kmol / h (10 t / h) to prepare oxygen-containing gas with an oxygen content of 5% mol / mol.

[0056] Oxygen-containing gas is introduced to the bottom of the reactor, while 300 t / h of liquid isobutane (isobutane / tert-butanol mass ratio = 70:30) enters the bubbling reactor. The oxygen reacts with the liquid isobutane in the reactor to produce tert-butyl hydroperoxide and tert-butanol, releasing heat. The heat of reaction is removed by the vaporization of isobutane, and the resulting liquid phase, containing approximately 8.5 wt% tert-butyl hydroperoxide, flows out of the reactor.

[0057] This embodiment allows for convenient adjustment of the reaction temperature while ensuring oxidation efficiency and safety.

[0058] When the tail gas concentration is high and the oxygen reaction is incomplete, the reaction temperature can be adjusted by increasing it. For example, when the ratio of isobutane-rich gas to nitrogen is 1:1.24 mol / mol, and the nitrogen content in the carrier gas is 56 vol%, the reactor reaction temperature can be controlled at 146℃. When the tail oxygen concentration is low and it is desirable to improve the selectivity of tert-butyl hydroperoxide, the reaction can be operated at a lower temperature: reduce the flow rate of isobutane-rich gas, increase the nitrogen flow rate, adjust the nitrogen content in the carrier gas to 66 vol%, and keep the total carrier gas flow rate and oxygen flow rate constant. The reactor reaction temperature can then be reduced to 142℃. More isobutane will vaporize, lowering the reaction temperature, thus increasing the tert-butyl hydrogen peroxide content in the liquid phase exiting the reactor to approximately 9.7%. If a further reduction in reactor operating temperature is desired, the oxygen flow rate can be increased while maintaining the total carrier gas flow rate and oxygen supply flow rate constant. Adjusting the flow ratio of nitrogen to isobutane-rich gas to achieve a nitrogen content of 90 vol% in the carrier gas lowers the reactor reaction temperature to 132°C. Due to the increased nitrogen inflow and vaporization of isobutane, heat is removed, resulting in a tert-butyl hydrogen peroxide content >13% in the liquid exiting the reactor.

[0059] This embodiment illustrates the convenience of the present invention in adjusting the reactor operating temperature. During the adjustment process, the oxygen content in the gas phase at any location within the reactor is always below the safety limit. This improves the operability of the oxidation reactor while ensuring the safety of the oxidation reaction operation.

[0060] Example 2:

[0061] As shown in Figure 1, 230 t / h of fresh liquid isobutane feed S9 (isobutane content ~70 wt%, the remaining main components are tert-butanol, methanol and acetone) is mixed with oxidation condensate S8 and sent to oxidation feed heating vaporizer 108 to be heated to 150°C. The distilled isobutane gas is used for the preparation of reactor carrier gas, while the heated liquid phase S1 enters the oxidation reactor group.

[0062] The oxidation reactor group can consist of multiple oxidation reactors connected in series. The number of oxidation reactors can be set from 1 to 10, preferably 2 to 6. Multiple oxidation reactors can be arranged side-by-side, at different heights, or in a horizontal multi-compartment configuration. Furthermore, to improve transport efficiency, a liquid transfer pump is installed between each oxidation reactor for transporting the oxidation liquid.

[0063] The oxidation reaction zone is equipped with three oxidation reactors (101, 102, and 103). The liquid feed S1 enters the first oxidation reactor 101 and reacts with oxygen inside the reactor. The resulting oxidized liquid containing approximately 6% tert-butyl hydrogen peroxide overflows by gravity into the second oxidation reactor 102 for further reaction. The oxidized liquid after the reaction contains approximately 12% tert-butyl hydrogen peroxide and then overflows by gravity into the third oxidation reactor 103 for further reaction. After the reaction is completed, the flow rate of the oxidized liquid flowing out of the third oxidation reactor 103 is 264 t / h, of which the tert-butyl hydrogen peroxide content is approximately 20%.

[0064] The oxygen-containing gases S2a / b / c entering the three oxidation reactors are parallel, and the oxygen content in the gas phase entering each reactor is the same, approximately 10 t / h. The oxygen content in the oxygen-containing gases after oxygenation is controlled at 5-6% vol, which is lower than the maximum safe limit for oxygen content in the gas phase, ensuring the safety of the oxidation reaction. To ensure uniform distribution of oxygen in the carrier gas, static mixers 112a / b / c are installed during oxygenation. To improve the selectivity of tert-butyl hydroperoxide and reduce its decomposition into tert-butanol, the reaction temperatures of the three reactors are progressively decreased to 146℃, 142℃, and 137℃, respectively. According to the method of this invention, the temperature in each reactor can be controlled by adjusting the ratio of nitrogen and isobutane-containing gas in the carrier gas S7a / b / c entering each reactor. In this embodiment, the nitrogen content in the carrier gas entering the three oxidation reactors (101, 102, 103) is 25 vol%, 49 vol%, and 66 vol%, respectively.

[0065] The tail gases flowing from the three oxidation reactors (101, 102, 103) converge into a stream S3 (temperature 141℃, pressure 3.66MPa), which enters the oxidation tail gas condenser 104 to be cooled to 55℃. Then, it enters the tail gas separator 105 to separate and remove high-boiling-point components such as isobutane, tert-butanol, and tert-butyl hydrogen peroxide from the oxidation tail gas. The non-condensable gas S6 enters the oxidation tail gas recirculation compressor 106 for pressurization. The pressurized recirculating nitrogen is divided into three streams and mixed with isobutane gas from the oxidation feed heating vaporizer 108 in the required ratio to form recirculating carrier gases S7a / b / c. After adding 5-6% vol of oxygen in proportion, the gases enter the three reactors (101, 102, 103) respectively to continue the reaction. The liquid phase S8 isobutane flowing out of the tail gas separator 105 is pressurized by pump 107 and returned to the oxidation feed heating vaporizer 108 for circulation. In addition, the oxidation feed heating vaporizer is divided into two devices: an isobutane vaporizer and an oxidation feed heater, which are used for vaporization and heating, respectively.

[0066] Example 3:

[0067] As shown in Figure 2, compared to Example 2, this example adds heat exchange between the oxidation tail gas and the isobutane feed, reducing the energy consumption of the entire oxidation operation.

[0068] The oxidation tail gas S3 has a temperature of 141°C and contains approximately 80% condensable components such as isobutane, tert-butanol, and tert-butyl hydroperoxide. The oxidation tail gas S3 is heat-exchanged with the oxidizing liquid feed S11. The liquid feed S11 is heated to 134°C and then enters the oxidation feed heating vaporizer 108. The liquid feed condensed from S3 has a high content of tert-butyl hydroperoxide and is directly returned to the first oxidation reactor 101. A heat exchanger is added before the oxidation tail gas condenser to recover heat. The preferred number of heat exchanger stages is 1 to 5. The condensate collected from each stage is preferably pumped into the oxidation reactor.

[0069] Compared to Example 2, this embodiment consumes ~61MW less heat.

[0070] In addition, a high-temperature condensate tank 110 and a high-temperature condensate pump 111 were added. The exhaust gas after heat exchange forms high-temperature condensate in the high-temperature condensate tank 110. The high-temperature condensate is preferentially sent to the oxidation reactor through the high-temperature condensate pump 111 to continue the oxidation reaction.

[0071] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for isobutane oxidation, characterized in that: Includes the following steps: S1. Carrier gas configuration: The isobutane-rich gas stream and the nitrogen-rich gas stream are mixed uniformly in a certain proportion to form the first carrier gas. In the nitrogen-rich gas stream, the nitrogen concentration is >80 vol%, and the oxygen concentration is <1 vol%. In the isobutane-rich gas stream, the isobutane concentration is >70 vol%, and the nitrogen content in the first carrier gas is 10-95 vol%. S2. Preparation of reaction carrier gas: Oxygen is mixed with the first carrier gas in a uniform ratio to form the second carrier gas, wherein the oxygen concentration is 1-10 vol%. S3. Oxidation reaction: The second carrier gas is introduced into the bottom of the oxidation reactor to react with the liquid isobutane in the oxidation reactor to generate tert-butyl hydrogen peroxide. The reaction temperature of the oxidation reactor is controlled by adjusting the nitrogen ratio in the first carrier gas, and the oxidation rate and tail oxygen concentration are controlled by adjusting the oxygen ratio in the second carrier gas.

2. The isobutane oxidation method according to claim 1, characterized in that: It also includes S4, tail gas and condensate circulation. The tail gas flowing out from the top of the oxidation reactor is condensed and compressed in sequence. The gas phase tail gas is used as the first carrier gas as a nitrogen-rich gas stream. A portion of the condensed liquid phase tail gas is vaporized and used as the first carrier gas as an isobutane-rich gas stream. The other portion is heated and enters the oxidation reactor as a reaction feedstock.

3. The isobutane oxidation method according to claim 2, characterized in that: The tail gas flowing out from the top of the oxidation reactor is condensed in stages, with condensation stages ranging from 1 to 5. The high-temperature condensate with a temperature greater than 110°C is returned to the oxidation reactor as a reaction feedstock.

4. The isobutane oxidation method according to claim 2, characterized in that: The exhaust gas flowing from the top of the oxidation reactor exchanges heat with liquid isobutane before being condensed and compressed.

5. The isobutane oxidation method according to claim 1, characterized in that: In step S3, the temperature of the oxidation reactor is maintained at 120-150℃, the reaction pressure is 2.8-4.5MPa, the oxidation reaction zone is set up in 1-10 stages, and the reaction temperature decreases step by step.

6. An isobutane oxidation system, characterized in that: The system includes an oxidation reactor group, an oxidation tail gas condenser connected to the tail gas outlet of the oxidation reactor group, an oxidation tail gas separator connected to the oxidation tail gas condenser, an oxidation tail gas recirculation compressor connected to the gas phase outlet of the oxidation tail gas separator, a tail gas condensate booster pump connected to the liquid phase outlet of the oxidation tail gas separator, and an oxidation feed heating vaporizer connected to the tail gas condensate booster pump. A liquid isobutane material inlet is connected to the oxidation feed heating vaporizer. The gas flowing out of the gas phase outlet of the oxidation feed heating vaporizer is mixed proportionally with the gas flowing out of the oxidation tail gas recirculation compressor to form a first carrier gas. The system also includes a static mixer and an oxygen supply device. The oxygen generated by the oxygen supply device is mixed with the first carrier gas in the static mixer to form a second carrier gas. The second carrier gas is connected to the oxidation reactor group, and the liquid phase outlet of the oxidation feed heating vaporizer is connected to the oxidation reactor group.

7. The isobutane oxidation system as described in claim 6, characterized in that: It also includes an oxidation tail gas heat exchanger disposed between the oxidation reactor group and the oxidation tail gas condenser, wherein the tail gas discharged from the oxidation reactor group exchanges heat with the liquid isobutane material and the tail gas condensate discharged by the tail gas condensate pump through the oxidation tail gas heat exchanger.

8. The isobutane oxidation system according to claim 7, characterized in that: It also includes a high-temperature condensate tank disposed between the oxidation tail gas heat exchanger and the oxidation tail gas condenser. The gas phase outlet of the high-temperature condensate tank is connected to the oxidation tail gas condenser, and the liquid phase outlet of the high-temperature condensate tank is connected to the oxidation reactor group through a high-temperature condensate pump.

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