A continuous apparatus for the production of ester compounds by oxidation of hydrocarbons in air
By designing a multi-stage series oxidation reactor and rationally setting the continuous device for alcohol feedstock inlet, the problems of solid intermediate product transfer and blockage in the process of converting hydrocarbon compounds into ester compounds were solved, realizing integrated continuous production of hydrocarbons into ester compounds and improving conversion efficiency and separation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGSHA MATERIALS TECH CO LTD
- Filing Date
- 2020-11-04
- Publication Date
- 2026-07-21
AI Technical Summary
Existing technologies cannot directly convert hydrocarbon compounds into ester compounds through continuous processes such as oxidation, esterification, and separation. There are problems such as the transfer of solid intermediate products and pipeline blockage, which prevents the integrated and continuous production of hydrocarbon-to-acid and acid-to-ester conversion processes.
Design a continuous device consisting of an oxidation unit, a flash evaporation unit, an esterification unit, and a distillation unit connected in series. Employ a multi-stage series oxidation reactor and a parallel settling tower. By optimizing the condensate circulation and the alcohol feedstock inlet, the flowability of the solid product is addressed, enabling continuous transfer and separation of acids.
It realizes the integrated continuous production of air oxidation, esterification and separation of hydrocarbon compounds, improves oxidation conversion efficiency, solves the problem of solid intermediate product transfer, reduces separation difficulty and reduces waste liquid generation.
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Figure CN114436841B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an organic chemical reaction apparatus, and more particularly to a continuous apparatus for the production of ester compounds by the air oxidation of hydrocarbons, belonging to the field of chemical technology. Background Technology
[0002] Carboxylic acid esters are important basic chemical raw materials, mainly used in the production of polymer materials, pharmaceutical synthesis, and the synthesis of fine chemical products. Current technologies for preparing ester compounds primarily use acids and alcohols as reactants in esterification reactions. However, acids can be obtained from hydrocarbons through oxidation. Therefore, current ester compound preparation involves two independent reaction and separation processes: acid preparation and ester preparation. Currently, there are no continuous reaction devices that obtain ester compounds from hydrocarbons through continuous processes of oxidation, esterification, and separation. In existing technologies, methods for obtaining carboxylic acids from hydrocarbons through oxidative dehydrogenation are relatively common, such as those described in US patent (U.S. Patent). S 10329222B2) discloses a method for making C 2～6 Oxidative dehydrogenation of alkanes to obtain C 2～6Regarding methods for producing adipic acid from cyclohexane, Chinese patent (CN111233652A) discloses a method for oxidizing cyclohexane to produce adipic acid. Chinese patent (CN121892C) discloses a method for producing adipic acid from cyclohexane using a 1-100 PPM monometallic porphyrin or μ-oxygen bimetallic porphyrin or a mixed catalyst composed of them and transition metal salts or oxides under conditions of 1-20 atm and 50-200℃. Chinese patent (CN101337879A) discloses a method for oxidizing cyclohexane for 45-120 minutes under the action of a catalyst such as a 1-50 PPM monometallic porphyrin, by introducing 5-12 atm of air or oxygen-enriched or oxygen-deficient air, controlling the reaction temperature at 140-160℃, and then flash-separating the cyclohexane to obtain adipic acid with a content of over 80%, etc. However, specific oxidation reaction devices are relatively rare in existing technologies. For example, Chinese patent (CN103755543A) discloses a method for producing adipic acid by oxidizing cyclohexane using air based on a gas-liquid-solid multiphase reaction separation synchronous reactor. The gas-liquid-solid multiphase reaction separation synchronous reactor includes a reaction tower and at least two isothermal settling towers connected to the bottom of the reaction tower. The reaction tower is equipped with a gas phase zone, an oxidation zone, and a gas outlet. During the reaction, cyclohexane is filled into the oxidation zone and the isothermal settling towers. Air is continuously introduced from the bottom of the oxidation zone and comes into contact with the cyclohexane to undergo an oxidation reaction. At the same time, the generated adipic acid solid is settled. The cyclohexane enters a constant-temperature settling tower, where it enters the oxidation zone through an external circulation system, allowing the reaction to proceed continuously. Adipic acid continues to settle in the settling tower until it is full. At this point, the reaction tower is switched to another constant-temperature settling tower filled with cyclohexane, and this process is repeated alternately for continuous production. While this device achieves a semi-continuous conversion of cyclohexane to adipic acid and separates the adipic acid, it does not involve the purification and esterification of adipic acid, nor the continuity of these processes. In reality, adipic acid also contains a large amount of byproducts such as succinic acid and valeric acid, which are difficult to separate from adipic acid. Chinese Patent (CN210855905U) discloses a production device for mixed dicarboxylic acid dimethyl esters. This device includes an esterification reactor, a flash evaporator, a distillation tower, and a methanol recovery tower. This device can achieve the esterification reaction of dicarboxylic acids and separate mixed dicarboxylic acid dimethyl esters with a purity ≥99.0%. This device can only use existing dicarboxylic acids as reactants to prepare ester compounds.
[0003] The reason why existing technologies cannot achieve the direct conversion of hydrocarbons into esters is that existing production technologies and equipment cannot solve the bottleneck technical problems of transferring solid intermediate products such as acids and clogging pipelines involved in the production process. It is this technical problem that makes it impossible to realize the integrated continuous industrial production process of converting hydrocarbons into acids and acids into esters. Summary of the Invention
[0004] In view of the shortcomings of existing methods for producing ester compounds from hydrocarbons, the purpose of this invention is to provide an integrated continuous production device that can realize the conversion of hydrocarbons into acids, the conversion of acids into esters, and the separation and purification of esters to obtain ester compounds. The device has a simple structure, reasonable design, wide applicability, and is conducive to large-scale promotion and application. It is particularly suitable for the integrated continuous production of ester compounds in which the intermediate oxidation product is a solid.
[0005] To achieve the above-mentioned technical objectives, the present invention provides a continuous apparatus for producing ester compounds by air oxidation of hydrocarbons, which consists of an oxidation unit, a flash evaporation unit, an esterification unit and a distillation unit connected in series.
[0006] The apparatus provided by this invention realizes the integrated and continuous completion of air oxidation, esterification and purification of hydrocarbon compounds, and finally obtains ester compounds, which solves the defects of the prior art that requires separate oxidation and esterification processes for the production process from hydrocarbons to ester compounds.
[0007] As a preferred embodiment, the oxidation unit consists of a single-stage oxidation reactor or a multi-stage oxidation reactor connected in series.
[0008] As a preferred embodiment, when the oxidation unit is composed of a single-stage oxidation reactor, the oxidation reactor consists of an oxidizer R, a condenser L, and settling towers SA and SB. The bottom of the oxidizer R is connected to the top of the settling towers SA and SB via a three-way pipe; the upper part of the oxidizer R is connected to the condenser L via two pipes; and the bottom of the settling towers SA and SB is connected to the flash evaporation unit via a three-way pipe.
[0009] As a preferred embodiment, when the oxidation unit is composed of multi-stage series oxidation reactors, each oxidation reactor consists of an oxidizer R, a condenser L, and settling towers SA and SB. The upper part of the oxidizer R is connected to the condenser L via two pipes. The upper part of the oxidizer R of the primary oxidation reactor is connected to the upper part of the oxidizer R of the next stage oxidation reactor via a pipe. The lower part of the oxidizer R of other oxidation reactors is connected to the upper part of the oxidizer R of the next stage oxidation reactor via a pipe. The lower part of the oxidizer R of the last stage oxidation reactor is connected to the top of the settling towers SA and SB of any stage oxidation reactor via a T-junction pipe. The bottom of the settling towers SA and SB of each oxidation reactor is connected to the flash evaporation unit via a T-junction pipe.
[0010] As a preferred embodiment, when the oxidation unit consists of a multi-stage series oxidation reactor, the multi-stage oxidation reactor comprises a primary oxidation reactor, n intermediate oxidation reactors connected in series (n = 1-3), and a final oxidation reactor. The primary oxidation reactor consists of an oxidizer R11, a condenser L110, and two parallel settling towers S1A4 and S1B5. The oxidizer R11 is connected to the condenser L1 via two pipes, and the oxidizer R11 is connected to the settling towers S1A and S1B via a three-way pipe. The intermediate oxidation reactors consist of an oxidizer R11, a condenser L110, and two parallel settling towers S1A4 and S1B5. n 2. Condenser L n 11 and two parallel settling towers S n A 6 and settling tower S n B7 composition, oxidizer R n With condenser L n The two are connected by two pipes, oxidizer R n With settling tower S n A and settling tower S n The B units are connected by a three-way pipe. The final oxidation reactor consists of oxidizer R3, condenser L3, and two parallel settling towers S3A and S3B. Oxidizer R3 is connected to condenser L3 by two pipes, and oxidizer R3 is connected to settling towers S3A and S3B by a three-way pipe. The upper part of oxidizer R1 is connected to oxidizer R... n The upper part is connected via a pipe to the oxidizer R. n The lower part of the oxidizer R3 is connected to the upper part of the oxidizer R3 via a pipe. The upper part of the oxidizer R3 is connected to the top of the settling tower S1A and the settling tower S1B, respectively. n A and settling tower S n The top of reactor B, as well as the tops of settling towers S3A and S3B, are connected via a T-junction pipe; when there are two or more intermediate reactors, all intermediate reactors are connected in series, with the lower part of the previous reactor connected to the upper part of the next reactor; settling towers S1A and S1B, settling tower S... n A and settling tower S n B, as well as the lower parts of settling towers S3A and S3B, are connected to the flash evaporation unit via T-junction pipes.
[0011] As a preferred embodiment, when the oxidation unit consists of multi-stage series oxidation reactors, the condensate outlets of the condensers at the top of all oxidation reactors are connected not only to their respective oxidizers but also to the condensate outlets of the condensers at the top of adjacent reactors via T-junctions or four-way pipes. The condenser L1 of the primary oxidation reactor R1 or the L3 of the final oxidation reactor R3 is connected to the intermediate oxidation reactor R... n L n The condenser condensate outlet is connected by a three-way pipe, and the intermediate oxidation reactor Rn L n The condensate outlet is connected to the condensate outlets of L1 and L3 simultaneously by a four-way pipe. The condensate can be selectively returned to any one or all reactors in any proportion by three-way switches 81, 82 and four-way switch 87.
[0012] The oxidation reactor involved in this invention is a common reactor in the industry, such as a reactor with an agitator or a bubbling reactor with a gravity settling plate. A common gas distributor can also be installed inside the reactor to uniformly distribute the oxidizing gas (air or oxygen, etc.), which is beneficial to improving the gas-liquid reaction efficiency. This device, through the design of multi-stage series reactors, can improve the oxidation conversion rate of hydrocarbon compounds.
[0013] As a preferred embodiment, the flash evaporation unit includes two flash towers, F1 and F2, connected in parallel. Flash towers F1 and F2 are connected to the oxidation unit and the esterification unit via T-junction pipes. The two flash towers, F1 and F2, are in parallel configuration. A T-junction pipe allows for switching between them, controlling the connection between one flash tower and the settling tower of the oxidation unit, and the other flash tower and the esterification reaction tower of the esterification unit. These two can be used alternately. The flash tower connected to the settling tower primarily serves as a storage container for the oxidation reaction liquid (containing solid products), while the flash tower connected to the esterification reaction tower is used to distill off unreacted liquid substances.
[0014] As a preferred embodiment, the upper part of flash tower F1 and flash tower F2 is provided with alcohol feed inlets 61 and 62 and feed steam outlets 59 and 60.
[0015] As a preferred embodiment, the esterification unit includes an esterification reaction tower 15.
[0016] As a preferred embodiment, the distillation unit includes distillation column I16 and distillation column II17 connected in series.
[0017] As a preferred embodiment, the oxidizer has a gas outlet at the top (for exhaust gas), a reaction liquid outlet at the top (for overflow of the reaction liquid), and an oxidation gas inlet (gas oxidant inlet) at the bottom. The primary reactor R1 has a hydrocarbon feedstock inlet at the bottom (for hydrocarbon feedstock introduction), and the intermediate reactor R... n The reaction liquid inlet of the final reactor R3 is located at the top of the reactor. During the continuous reaction process, the hydrocarbon feedstock enters the oxidizer from the bottom of the primary oxidizer and overflows from the top of the oxidizer. In all subsequent oxidation reactors, the oxidant liquid from the previous reactor is introduced from the top of the reactor and flows out from the bottom. For all oxidation reactors, the gas enters from the bottom of the oxidizer and exits from the top of the oxidizer into the condenser.
[0018] As a preferred embodiment, the bottom of the settling tower is provided with an acid product outlet (for discharging acid products from the settling tower), and the acid product outlet is connected to the flash evaporation unit.
[0019] As a preferred embodiment, flash distillation towers F1 and F2 are equipped with hydrocarbon feedstock outlets at the top (for returning evaporated hydrocarbon feedstocks to the oxidation unit), acid product inlets in the middle (connected to the bottom of the settling tower), alcohol feedstock inlets at the top (for alcohol introduction), and acid outlets at the bottom (connected to the esterification reaction tower). Unreacted hydrocarbon feedstocks distilled from flash distillation towers F1 or F2 are recovered from the hydrocarbon feedstock outlet, and after simple cooling, water washing, and settling separation, are returned to the oxidation unit for recycling. The alcohol feedstock inlet is for introducing alcohol feedstocks for the esterification reaction. However, this invention places the alcohol feedstock inlet in the flash distillation unit, not the esterification reaction unit, primarily to address the technical problem of difficult acid transfer of solid products during continuous production. In the flash distillation unit, after the hydrocarbon feedstock is flash-evaporated, some acidic intermediate solid products crystallize out, resulting in poor fluidity. Introducing alcohol feedstock significantly improves acid fluidity, allowing for the transfer of acidic intermediate solid products without the need for additional solvents, thus facilitating continuous production.
[0020] The actual production process of the apparatus provided by this invention for producing ester compounds from hydrocarbon feedstocks is as follows: The hydrocarbon feedstock (which may also contain some solvent) containing dissolved catalyst is filled into the primary oxidizer R1 and the intermediate oxidizer R2. n and the final oxidizer R3 (approximately at the height of oxidizer R2 / 3) and all settling towers S1A, S n A, S3A, S1B, S n B, S3B; The primary oxidizer R1 and intermediate oxidizer R... n The final oxidizer R3 is controlled via a three-way pipe to connect with its corresponding settling towers S1A and S1A. n A and settling tower S3A are connected, settling tower S1A and settling tower S n A and settling tower S3A are connected to flash tower F1; from oxidizer R1, R n Air or oxygen is introduced into the R3 oxidizing gas inlet, and the temperature is raised to carry out the oxidation reaction. Oxidizers R1 and R2... n The high-temperature reaction exhaust gases from R3 and R3 enter condensers L1 and L2 respectively through the reaction gas outlet. n L3, the coolant in the condenser returns to the oxidizer R1 and R2 via the coolant inlet. n and R3; oxidizer R1, R n The solid acid products generated in R3 and R3, under the action of gravity, flow out of the solid product outlet and pass through settling towers S1A and S1A respectively. n The solid products from A and S3A settle into settling towers S1A and S2A.n A, S3A, and simultaneously settling towers S1A and S n A. The hydrocarbon feedstock in S3A is replaced and enters oxidizers R1 and R2. n It undergoes an oxidation reaction with R3, until the sedimentation towers S1A and S1A are settled. n When there are crystalline acidic solid products in settling tower S3A and settling tower A, switch to oxidizer R1 and oxidizer R2 via a three-way valve. n The oxidizer R3 and its corresponding settling towers S1B and S1B are respectively connected to the settling tower S. n B and settling tower S3B are connected, oxidizers R1 and R... n The solid acid products generated in R3 and R3, under the action of gravity, flow out of the solid product outlet and pass through settling towers S1B and S1B, respectively. n The solid products from B and S3B settle into the settling towers S1B and S. n B, S3B, while settling tower S1A, settling tower S n A and settling tower S3A and oxidizers R1 and R n By disconnecting from R3, alternating connections are achieved between the oxidizer R and settling towers A and B.
[0021] After the switching between settling towers SB and SA is completed, the hydrocarbon feedstock containing dissolved catalyst is continuously introduced into the oxidizer R1 from the hydrocarbon feedstock inlet at the bottom of the first oxidizer R1. The hydrocarbon feedstock undergoes the first oxidation in the oxidizer R1, and the resulting solid product acid settles into the settling tower S1B through the solid product inlet under gravity from the solid product outlet. The reaction liquid overflows from the reaction liquid outlet at the top of the oxidizer R1 and flows into the oxidizer R2. n The second oxidation reaction is completed in the oxidizer R. n The solid acid product generated in the process flows out of the solid product outlet and into the settling tower S under the action of gravity. n The solid products of B settle into the settling tower S through the inlet. n B, simultaneously settling tower S n The hydrocarbon feedstock in B is replaced and enters the oxidizer R. n Oxidation occurs, and the reaction solution flows from oxidizer R. n The reaction liquid from the lower outlet is discharged into the final oxidizer R3 to complete the final oxidation reaction. The generated solid product acid settles from the solid product outlet through the solid product inlet of settling tower S3B under gravity. The reaction liquid is discharged from the reaction liquid outlet at the lower part of oxidizer R3 and passes through settling tower S1A and settling tower S2B. n The oxidizing liquid inlet of settling tower S1A and settling tower S3A enters the settling tower S1A and settling tower S3A. n A and settling tower S3A, and drive settling tower S1A and settling tower S nThe acid products from settling tower S1A and settling tower S3A enter the flash tower F1 through the oxidation liquid inlet from the oxidation liquid outlet for stirring and flash evaporation; when settling tower S1A and settling tower S3A are in contact with each other, the acid products from settling tower S1A and settling tower S3A are stirred and flashed. n The acid products from reactors A and S3A are carried into flash evaporator F by the oxidizing liquid from oxidation reactor R3, and then switched back to oxidation reactors R1 and R2. n R3 is connected to settling towers S1A and S1A respectively. n Connect A and S3A, and connect the settling towers S1B and S... n The outlets at the lower parts of B and S3B are switched to be disconnected from flash tower F1 and connected to flash tower F1. The oxidizing liquid flowing out of oxidation reactor R3 flows again through settling towers S1B and S2B. n B and S3B then enter flash tower F2; at this time, flash tower F1 is disconnected from the settling tower, and the reaction liquid in flash tower F1 enters flash evaporation. Due to the sudden decompression, the low-boiling-point hydrocarbon raw materials in flash tower F1 flash evaporate into gas, while the high-boiling-point acid products remain in flash tower F1. By controlling the flash evaporation pressure and flash tower temperature, the hydrocarbons and oxidation products are completely separated. The hydrocarbons separated by flash evaporation are cooled, washed with water, and allowed to settle for further separation before being recycled. When the hydrocarbons in flash tower F1 are completely flash evaporated... Then, alcohol is introduced. The acid solids in flash distillation tower F1 are carried by the alcohol into the esterification tower for esterification. Once all the acid in flash distillation tower F1 has been carried into the esterification tower, the addition of alcohol to flash distillation tower F1 is stopped. Pressure is maintained to ensure that the pressure of flash distillation tower F1 is consistent with the oxidation reaction system. Flash distillation tower F1 is then switched to be connected to the settling tower. This continuous switching between the oxidation unit and flash distillation towers F1 and F2 ensures that the acid obtained from the oxidation unit is separated from the unreacted hydrocarbons in the flash distillation unit and enters the esterification unit. In the esterification unit, the acid and alcohol undergo a catalytic esterification reaction. The esterification reaction liquid is introduced into distillation tower I for distillation to separate alcohol, byproducts, intermediates, and ester compounds. The alcohol is returned to the flash distillation unit, the intermediates are returned to the oxidation unit, and the ester compounds are distilled into distillation tower II for high-purity ester compounds.
[0022] The innovative design of the multi-stage series oxidation reactor in the device provided by this invention is as follows: First, the reaction liquid outlet of the final oxidizer R3 is not connected to the oxidation reaction tower to achieve the recycling of aliphatic hydrocarbon feedstock or to be directly used for hydrocarbon feedstock discharge recovery. Instead, the reaction liquid outlet of the oxidizer R3 is connected to settling towers S1A and S1B, and settling tower S... n A and settling tower S nB. The tops of settling towers S3A and S3B are connected, primarily to address the technical problem that acidic intermediates, mainly solid products, deposit in the settling towers during the oxidation reaction. Due to their poor fluidity, these products are difficult to transfer, hindering continuous production. The key to this device is utilizing the reaction liquid overflowing from oxidizer R3 as the flowing medium to improve the fluidity of the acidic products in each settling tower. This enables the transfer of solid acid products between reactors and between the reactor and the flash tower, while also preventing the precipitation of solid products in the oxidation reactor and the blockage of pipelines, thus achieving a continuous production process for systems containing solid materials. Secondly, all components related to the oxidation reactor... The condensate outlet on the condenser is connected via a three-way or four-way pipe. The condensate can be selectively returned to any or all reactors in any proportion using three-way switches 81 and 82 and four-way switch 87. This design is beneficial for adjusting the residence time distribution of reactants in different oxidation reactors and for controlling the distribution of reaction products and oxidation depth within the oxidation reactors, thereby achieving ideal oxidation selectivity. Thirdly, the device of this invention places the alcohol feedstock inlet in the flash evaporation unit instead of the esterification reaction unit, solving the technical problem of transferring solid acid from the flash evaporation tower to the esterification tower, realizing the transfer of intermediate solid acid products, and facilitating continuous production.
[0023] Compared with the prior art, the beneficial technical effects of this invention are as follows:
[0024] The apparatus provided by this invention enables the continuous production of ester compounds by integrating air oxidation, esterification, and separation using hydrocarbon compounds as direct raw materials. This overcomes the shortcomings of existing technologies where the oxidation and esterification processes for hydrocarbons require independent intermittent operation steps, making continuous production difficult.
[0025] The device provided by this invention has a simple structure and reasonable design, and meets the production requirements for preparing corresponding ester compounds from most hydrocarbons.
[0026] The device provided by this invention uses a multi-stage series oxidation reactor, which can ensure a high oxidation conversion efficiency of hydrocarbons. Moreover, by designing parallel settling towers, the oxidation unit can be carried out continuously.
[0027] The device provided by this invention has a reasonable design of esterification and separation units, which can solve the technical problem of difficult separation and purification of mixed acid products from hydrocarbon oxidation in the prior art. By first esterifying and then separating, the mixed acid is converted into an easily separable esterified product, reducing the separation difficulty.
[0028] The present invention provides a flash evaporation unit and a distillation unit that enable the recovery and reuse of reaction raw materials and intermediate products, thereby reducing the generation of waste liquid.
[0029] The apparatus provided by this invention solves the technical problem of the difficulty in transferring intermediate solid acid products in a continuous production process from hydrocarbon feedstock to acid to ester. This apparatus, on the one hand, connects the reaction liquid outlet of oxidizer R3 to settling towers S1A and S1B, and settling tower S... n A and settling tower S n B. The tops of settling towers S3A and S3B are connected, and hydrocarbon reaction feedstocks are used to realize the transfer of acid solid products between the oxidation unit and the flash unit. On the other hand, the methanol feedstock inlet is designed in the flash unit, and alcohol feedstocks are used to realize the transfer of solid acid between the flash unit and the esterification unit, thus realizing a continuous production process of the reaction system containing solid intermediate products.
[0030] The device provided by this invention can also be used for continuous production in chemical processes that generate solid intermediates or products. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of an apparatus for the air oxidation of hydrocarbon feedstocks to produce ester compounds.
[0032] Wherein, 1 is the primary oxidizer R1, 2 is the intermediate oxidizer Rn, 3 is the oxidizer R3, 4 is the settling tower S1A, 5 is the settling tower S1B, and 6 is the settling tower S... n A, 7 represents the settling tower S. n B, 8 are settling tower S3A, 9 are settling tower S3B, 10 are gas cooler L1, and 11 are gas cooler L n 12 is gas cooler L3, 13 is flash tower F1, 14 is flash tower F2, 15 is esterification reaction tower, 16 is distillation tower I, 17 is distillation tower II, 18 is back pressure valve, 19-21 are gas inlets, 22 is hydrocarbon feedstock inlet, 23-24 are oxidation liquid inlets, 25-27 are oxidation liquid outlets, 28-30 are reaction gas outlets, 31-33 are oxidizer solid product outlets, 34-39 are solid product inlets, 40-45 are oxidation liquid outlets, 46-51 are final reactor oxidation liquid inlets, 51-54 are condensate inlets, 55-56 are oxidation liquid inlets, 57-58 are alcohol and acid mixture outlets, 59-60 are volatile component outlets, and 61-62 are alcohol feedstock inlets. 63 is the inlet for the mixture of alcohol and acid; 64 is the outlet for the esterified liquid; 65 is the inlet for the esterified liquid; 66 is the outlet for the alcohol; 67 is the outlet for the non-volatile non-esterified oxidized component; 68 is the outlet for esters and high-boiling-point liquid substances; 69 is the inlet for esters and high-boiling-point liquid substances; 70 is the outlet for esters; 71 is the outlet for non-ester high-boiling-point liquids; 72-86 are three-way connection points; 87-88 are four-way connection points. Detailed Implementation
[0033] The following specific embodiments are intended to provide a detailed description of the present invention in conjunction with the accompanying drawings, but the scope of protection of the present invention is not limited to the specific embodiments.
[0034] The present invention provides an apparatus for producing ester compounds from hydrocarbon feedstocks, specifically as follows: Figure 1 As shown. The main body of the device consists of an oxidation unit, a flash evaporation unit, an esterification unit, and a distillation unit connected in series. The oxidation unit is used to oxidize hydrocarbon feedstocks into acid compounds from air, and it consists of a primary oxidation reactor, an intermediate oxidation reactor, and a final oxidation reactor connected in series. The primary oxidation reactor consists of an oxidizer R11 and two parallel settling towers S1A 4 and S1B 5. The oxidizer R1 is connected to the settling towers S1A and S1B via a three-way pipe, and the oxidizer R1 can be switched to connect to the settling tower S1A or the settling tower S1B. The intermediate oxidation reactor consists of an oxidizer R11, an intermediate oxidation reactor, and a final oxidation reactor. n 2 and two parallel settling towers S n A 6 and settling tower S n B7 is composed of oxidizer R. n With settling tower S n A and settling tower S n B is connected to the oxidizer R via a three-way pipe. n With settling tower S n A or oxidizer R n With settling tower S n B can be switched and connected; the final oxidation reactor consists of oxidizer R3 and two parallel settling towers S3A 8 and S3B 9. Oxidizer R3 and settling towers S3A and S3B are connected by a three-way pipe, and oxidizer R3 and settling tower S3A or oxidizer R3 and settling tower S3B can be switched and connected; the reaction liquid outlet 25 of oxidizer R1 is connected to oxidizer R n The oxidizing liquid inlet 23 is connected to the oxidizer R. n The reaction liquid outlet 26 is connected to the oxidation liquid inlet 24 of oxidizer R3, and the reaction liquid outlet 27 of oxidizer R3 is connected to settling towers S1A and S1B, and settling tower S n A and settling tower S n B. The final reaction liquid inlets 46-51 at the top of settling towers S3A and S3B are connected via T-junctions, which can control the connection between oxidizer R3 and settling towers S1A and S2B. n A and settling tower S3A or settling tower S1B, settling tower S nB is connected to settling tower S3B. The bottom of each settling tower is connected to the flash evaporation unit via a pipe. The flash evaporation unit is mainly used to separate acid products from unreacted hydrocarbon feedstock, recover hydrocarbon feedstock, and realize its recycling. The flash evaporation unit includes flash towers F1 13 and F2 14 connected in parallel. Flash towers F1 and F2 are connected to the oxidation unit and to the esterification unit via T-junctions. The T-junctions can switch the connection between flash tower F1 and the oxidation unit and flash tower F2 and the esterification unit, or switch the connection between flash tower F2 and the oxidation unit and flash tower F1 and the esterification unit. The bottom of the settling tower of the oxidation unit is connected to the acid product inlet 55 in the middle of flash towers F1 and F2 via a T-junction. Flash towers F1 and F2 have hydrocarbon feedstock outlets 59 at the top and acid outlets 57 and alcohol feedstock inlets 61 at the bottom. The acid outlet at the bottom of the flash distillation tower is connected to the esterification unit, which is primarily an esterification reaction tower filled with conventional esterification catalysts, mainly used for the esterification reaction of acids and alcohols. The esterification unit is connected to the distillation unit, which includes two distillation columns, I16 and II17, connected in series. Distillation column I is used to separate the esterification reaction products from the alcohol feedstock, while distillation column II is used for the distillation separation of various ester compounds.
[0035] The apparatus for producing ester compounds from hydrocarbon feedstock by air oxidation provided by this invention is used in the following process: a primary oxidizer R11 and an intermediate oxidizer R... n 2. Oxidizer R3; 3. Settling tower S1A; 4. Settling tower S1B; 5. Settling tower S... n A 6, Settlement Tower S n B 7, Settling tower S3A 8, Settling tower S3B 9 are filled with hydrocarbon feedstock containing dissolved catalyst; primary oxidizer R1 1, intermediate oxidizer R n 2 and oxidizer R3 are controlled by a three-way pipe to their corresponding settling towers S1A and S1A respectively. n A6 and settling tower S3A8 are connected, settling towers S1A4 and S... n A6 and S3A8 are connected to flash tower F1; then simultaneously from oxidizing gas inlet 19 at the bottom of oxidizer R1, oxidizer R n Oxidizing gas inlet 20, oxidizer R3, oxidizing gas inlet 21 to oxidizer R1, R n Air or oxygen is introduced into R3 to raise the temperature and carry out the oxidation reaction; oxidizers R1 and R n The high-temperature reaction tail gases from R3 enter condensers L1 and L2 respectively through reaction gas outlets 28, 29, and 30. n The coolant in the condenser returns to the oxidizer R1 and R2 via coolant inlets 52, 53 and 54. n and R3; oxidizer R1, Rn The solid acid products generated in R3, under the influence of gravity, flow out of solid product outlets 31, 32, and 33 respectively through settling towers S1A and S1B. n Solid products from A and S3A flow into settling towers S1A and S3A via inlets 34, 36, and 38, settling into the settling towers. n A, S3A, and simultaneously settling towers S1A and S n A. The hydrocarbon feedstock in S3A is replaced and enters oxidizers R1 and R2. n It undergoes an oxidation reaction with R3; when settling tower S1A and settling tower S... n The acid products from settling tower S3A and the settling tower S3A are carried into flash tower F1 by the oxidizing liquid from oxidation reactor R3. After that, the oxidizer R1 and the oxidizer R2 are switched through a three-way switch. n The oxidizer R3 and its corresponding settling towers S1B and S1B are respectively connected to the settling tower S. n Connect B and settling tower S3B, and connect settling towers S1A and S... n A and S3A and oxidizers R1 and R n By disconnecting from R3, alternating connections are achieved between the oxidizer R and settling towers A and B.
[0036] After the switchover is complete, oxidizers R1 and R2... n The solid acid products generated in R3, under the influence of gravity, flow out of solid product outlets 31, 32, and 33 respectively through settling towers S1B and S2B. n Solid products from B and S3B flow into settling towers S1B and S3B via inlets 35, 37, and 39, settling into the settling towers. n B, S3B, Next, the hydrocarbon feedstock containing dissolved catalyst is continuously introduced into oxidizer R1 and S1A from the hydrocarbon feedstock inlet 22 at the bottom of the first oxidizer R1. The hydrocarbon feedstock undergoes the first oxidation in oxidizer R1, and the resulting solid product acid settles into settling tower S1B through the solid product outlet 32 and the solid product inlet 35 under gravity. The reaction liquid overflows from the reaction liquid outlet 25 at the top of oxidizer R1 and exits from oxidizer R1. n The upper oxidizing liquid inlet 23 flows into the oxidizer R n The second oxidation reaction is completed in the oxidizer R. n The solid acid product generated in the process flows out of the solid product outlet 32 and into the settling tower S under the action of gravity. n The solid products of B settle into the settling tower S at inlet 37. n B, simultaneously settling tower S n The hydrocarbon feedstock in B is replaced and enters the oxidizer R. n Oxidation occurs, and the reaction solution flows from oxidizer R. nThe reaction liquid is discharged from the lower reaction outlet 26 and undergoes the final oxidation reaction in the final oxidizer R3. The generated solid product acid settles into the settling tower S3B under gravity through the solid product outlet 33 and the solid product inlet 39. The reaction liquid is discharged from the reaction liquid outlet 27 at the bottom of the oxidizer R3 and passes through the settling towers S1A and S2B. n The oxidized liquid from the final reactor of settling tower S1A and settling tower S3A flows into settling tower S1A and settling tower S3A through inlets 46, 48, and 50. n A and settling tower S3A, and drive settling tower S1A and settling tower S n The acid products from sedimentation towers S1A and S3A are produced by sedimentation towers S1A and S3A. n The oxidizing liquid outlets 40, 42, and 44 of settling tower S1A and settling tower S3A enter the interior of flash tower F1 through the oxidizing liquid inlet 55 for stirring and flash evaporation; when settling tower S1A and settling tower S3A... n The acid products from reactor A and settling tower S3A are carried into flash tower F1 by the oxidizing liquid from oxidation reactor R3, and then switched back to oxidation reactors R1 and R2. n R3 is connected to settling towers S1A and S1A respectively. n Connect A and S3A, and connect the settling towers S1B and S... n The outlets at the lower parts of B and S3B are switched to be disconnected from flash tower F1 and connected to flash tower F2. The oxidizing liquid flowing out of oxidation reactor R3 flows again through settling towers S1B and S2B. n B and S3B then enter flash tower F2; at this time, flash tower F1 is disconnected from the settling tower, and the reaction liquid in flash tower F1 enters flash evaporation; due to the sudden depressurization in flash tower F1, the low-boiling-point hydrocarbon raw material flashes into gas, while the high-boiling-point acid products remain in flash tower F1. By controlling the flash evaporation pressure and flash tower temperature, the hydrocarbons and oxidation products are completely separated. The hydrocarbons separated by flash evaporation are cooled, washed with water, and allowed to settle for further separation before being recycled; when the hydrocarbons in flash tower F1 are completely flash evaporated... Then, alcohol is introduced. The acid solids in flash distillation tower F1 are carried by the alcohol into the esterification tower for esterification. Once all the acid in flash distillation tower F1 has been carried into the esterification tower, the addition of alcohol to flash distillation tower F1 is stopped. Pressure is maintained to ensure that the pressure of flash distillation tower F1 is consistent with the oxidation reaction system. Flash distillation tower F1 is then switched to be connected to the settling tower. This continuous switching between the oxidation unit and flash distillation towers F1 and F2 ensures that the acid obtained from the oxidation unit is separated from the unreacted hydrocarbons in the flash distillation unit and enters the esterification unit. In the esterification unit, the acid and alcohol undergo a catalytic esterification reaction. The esterification reaction liquid is introduced into distillation tower I for distillation to separate alcohol, byproducts, intermediates, and ester compounds. The alcohol is returned to the flash distillation unit, the intermediates are returned to the oxidation unit, and the ester compounds are distilled into distillation tower II for high-purity ester compounds.
[0037] In the above process, the connection selection of three-way switch 72-74 realizes the connection switching between reactor R and settling towers SA and SB; the connection selection of three-way switch 78-80 realizes the connection switching between the reaction liquid flowing out of the final oxidation reactor and settling towers SA and SB; the connection selection of three-way switch 75-77 realizes the connection switching between the effluent from settling towers SA and SB and flash evaporator F; the connection selection of three-way switch 83 realizes the connection switching between flash evaporator F1 and flash evaporator F2 and the effluent from the settling tower; and the connection selection of three-way switch 84 realizes the connection switching between flash evaporator F1 and flash evaporator F2 and the esterification tower.
[0038] Application Implementation
[0039] The following examples illustrate the production of dimethyl adipate from cyclohexane by air catalytic oxidation using the apparatus provided by the present invention.
[0040] Example 1
[0041] 1) A mixture of cyclohexane and 30 PPM tetraphenylporphyrin cobalt enters a three-stage oxidation reaction tower. The oxidation reaction conditions are: temperature 155℃, total reaction time 3.5 hours, and air pressure 14 atm. Solid diacid products accumulate in the settling tower. The oxidized liquid escaping from the R3 oxidizer contains intermediate and by-products such as cyclohexanol, cyclohexanone, valeric acid, and cyclohexane. The cyclohexane conversion rate is 32%.
[0042] 2) The diacid product and the oxidizing liquid escaping from the R3 oxidizer are mixed and flow into the flash tower. The conditions of the flash tower are controlled as follows: temperature is 78℃ and pressure is 0.6 atm. The evaporated cyclohexane is cooled and recovered and returned to the oxidation process for recycling. The remaining mixture in the flash tower contains cyclohexanol, cyclohexanone and mixed acids.
[0043] 3) The mixture in the flash evaporator is mixed and dissolved with methanol and then enters the esterification reaction tower for esterification reaction. The esterification reaction conditions are: the molar ratio of methanol to the mixed acid in the mixture is 1.4:1 (measured by the molar amount of carboxyl groups in the mixed acid), and the reaction is carried out at 75°C for 8 hours in the presence of a solid acid catalyst. The esterification conversion rate of the mixed acid is 98%.
[0044] 4) Esterification reaction products are introduced into a distillation column: First, excess methanol is recovered by distillation at a pressure of 84 kPa and a temperature of 48°C. The methanol is returned to the esterification reaction process. Then, methyl valerate is recovered by distillation at a pressure of 33 kPa and a temperature of 60°C. Next, a mixture of cyclohexanol and cyclohexanone is recovered by distillation at a pressure of 12 kPa and a temperature of 75°C. The cyclohexanol and cyclohexanone are directly returned to the oxidation unit. Finally, the mixed diacid ester is recovered by distillation at a pressure of 2 kPa and a temperature of 95°C.
[0045] 5) The mixed diacid esters were subjected to vacuum distillation with 25 trays. The distillation process was carried out at a pressure of 1.5 kPa and a bottom temperature of 125 °C. 99% dimethyl succinate, 99% dimethyl glutarate, and 99% dimethyl adipate were collected from the top, middle, and bottom of the distillation vessel, respectively. The proportion of dimethyl adipate was 60%.
[0046] Example 2
[0047] 1) A mixture of cyclohexane, 20 PPM tetraphenylporphyrin cobalt, and 15 PPM cobalt acetate enters a three-stage oxidation reaction tower. The oxidation reaction conditions are: temperature 165℃, total reaction time 2.5 hours, and air pressure 15 atm. Solid diacid products accumulate in the settling tower. The oxidized liquid escaping from the R3 oxidizer contains intermediate and by-products such as cyclohexanol, cyclohexanone, valeric acid, and cyclohexane. The cyclohexane conversion rate is 32%.
[0048] 2) The diacid product and the oxidizing liquid escaping from the R3 oxidizer are mixed and flow into the flash tower. The conditions of the flash tower are controlled as follows: temperature is 85℃ and pressure is 0.8atm. The evaporated cyclohexane is cooled and recovered and returned to the oxidation process for recycling. The remaining mixture in the flash tower contains cyclohexanol, cyclohexanone and mixed acids.
[0049] 3) The mixture in the flash evaporator is mixed and dissolved with methanol and then enters the esterification reaction tower for esterification reaction. The esterification reaction conditions are: the molar ratio of methanol to the mixed acid in the mixture is 1.8:1 (measured by the molar amount of carboxyl groups in the mixed acid), and the reaction is carried out at 85°C for 6.5 hours in the presence of a solid acid catalyst. The esterification conversion rate of the mixed acid is 97%.
[0050] 4) Esterification reaction products are introduced into a distillation column: First, excess methanol is recovered by distillation at a pressure of 90 kPa and a temperature of 50 °C. The methanol is returned to the esterification reaction process. Then, methyl valerate is recovered by distillation at a pressure of 38 kPa and a temperature of 64 °C. Then, a mixture of cyclohexanol and cyclohexanone is recovered by distillation at a pressure of 16 kPa and a temperature of 85 °C. The cyclohexanol and cyclohexanone are directly returned to the oxidation unit. Finally, the mixed diacid ester is recovered by distillation at a pressure of 3 kPa and a temperature of 105 °C.
[0051] 5) The mixed diacid esters were subjected to vacuum distillation with 30 trays. The distillation process was carried out at a pressure of 1.4 kPa and a bottom temperature of 128°C. 99% dimethyl succinate, 99% dimethyl glutarate, and 99% dimethyl adipate were collected from the top, middle, and bottom of the distillation vessel, respectively. The proportion of dimethyl adipate was 56%.
Claims
1. A continuous apparatus for the production of ester compounds by the air oxidation of hydrocarbons, characterized in that: It is composed of an oxidation unit, a flash evaporation unit, an esterification unit, and a distillation unit connected in series; the oxidation unit is a single-stage oxidation reactor or is composed of multiple oxidation reactors connected in series. When the oxidation unit is composed of a single-stage oxidation reactor, the oxidation reactor consists of an oxidizer R, a settling tower SA and a settling tower SB, and a condenser L. The bottom of the oxidizer R is connected to the top of the settling tower SA and the settling tower SB through a three-way pipe; the upper part of the oxidizer R is connected to the condenser L; and the bottom of the settling tower SA and the settling tower SB is connected to the flash evaporation unit through a three-way pipe. When the oxidation unit is composed of multi-stage series oxidation reactors, each oxidation reactor consists of an oxidizer R, a condenser L, a settling tower SA, and a settling tower SB. The upper part of the oxidizer R is connected to the condenser L through two pipes, and the bottom of the oxidizer R is connected to the top of the settling tower SA and the settling tower SB through a T-junction. The upper part of the oxidizer R of the primary oxidation reactor is connected to the upper part of the oxidizer R of the next stage oxidation reactor through a pipe. The lower part of the oxidizer R of other oxidation reactors is connected to the upper part of the oxidizer R of the next stage oxidation reactor through a pipe. The lower part of the oxidizer R of the last stage oxidation reactor is connected to the top of the settling tower SA and the settling tower SB of any stage oxidation reactor through a T-junction. The bottom of the settling tower SA and the settling tower SB of each oxidation reactor is connected to the flash evaporation unit through a T-junction. The flash evaporation unit includes two parallel flash evaporation towers F1 and F2 with stirring. Flash evaporation towers F1 and F2 are connected to the oxidation unit and the esterification unit respectively through three-way pipes. The lower part of flash evaporation towers F1 and F2 is provided with alcohol feed inlet. The esterification unit includes an esterification reaction tower; The distillation unit includes distillation column I and distillation column II connected in series.
2. The continuous apparatus for producing ester compounds by air oxidation of hydrocarbons according to claim 1, characterized in that: When the oxidation unit is composed of multi-stage series oxidation reactors, the multi-stage oxidation reactor consists of one primary oxidation reactor, n intermediate oxidation reactors connected in series (n being 1-3), and one final oxidation reactor. The primary oxidation reactor consists of an oxidizer R1, a condenser L1, and two parallel settling towers S1A and S1B. The oxidizer R1 is connected to the condenser L1 via two pipes, and the oxidizer R1 is connected to the settling towers S1A and S1B via a three-way pipe. The intermediate oxidation reactor consists of an oxidizer R1... n Condenser L n and two parallel settling towers S n A and settling tower S n B consists of oxidizer R. n With condenser L n The two are connected by two pipes, oxidizer R n With settling tower S n A and settling tower S n The B units are connected by a three-way pipe. The final oxidation reactor consists of oxidizer R3, condenser L3, and two parallel settling towers S3A and S3B. Oxidizer R3 and condenser L3 are connected by two pipes, and oxidizer R3 is connected to settling towers S3A and S3B by a three-way pipe. The upper part of oxidizer R1 is connected to oxidizer R... n The upper part is connected via a pipe to the oxidizer R. n The lower part of the oxidizer R3 is connected to the upper part of the oxidizer R3 via a pipe. The upper part of the oxidizer R3 is connected to the top of the settling tower S1A and the settling tower S1B, respectively. n A and settling tower S n The top of B, as well as the tops of settling towers S3A and S3B, are connected via a T-junction pipe; when there are two or more intermediate oxidation reactors, all intermediate oxidation reactors are connected in series, with the lower part of the previous reactor connected to the upper part of the next reactor; settling towers S1A and S1B, settling tower S... n A and settling tower S n B, as well as the lower parts of settling towers S3A and S3B, are connected to the flash evaporation unit via T-junction pipes.
3. A continuous apparatus for producing ester compounds by air oxidation of hydrocarbons according to claim 1, characterized in that: When the oxidation unit consists of multi-stage series oxidation reactors, the condensate outlets of the condensers at the top of all oxidation reactors are connected not only to their respective oxidizers, but also to the condensate outlets of the condensers at the top of adjacent reactors via T-junctions or four-way pipes. The condenser L1 of the primary oxidation reactor R1 or the L3 of the final oxidation reactor R3 is connected to the intermediate oxidation reactor R... n L n The condenser condensate outlet is connected by a three-way pipe, and the intermediate oxidation reactor R n L n The condensate outlet is connected to the condensate outlets of L1 and L3 simultaneously by a four-way pipe. The condensate can be selectively controlled to return to any one or all reactors in any proportion by a three-way switch and a four-way switch.