Microreactor-separation system and method

Abstract

This invention discloses a multiphase microreaction-separation system, comprising: a micro-interface reaction unit, a membrane separation unit, and a circulation unit. The micro-interface reaction unit is used for gas-liquid-solid reactions; the circulation unit receives a mixed slurry of a solid catalyst and solvent, along with circulating slurry from the micro-interface reaction unit, and transports it to the membrane separation unit; the membrane separation unit separates the reaction solution through a membrane and transports the circulating slurry back to the micro-interface reaction unit. This invention is the first to couple the high-efficiency heat and mass transfer performance of a micro-interface reactor with the high-efficiency dynamic separation performance of a membrane separation unit, achieving efficient gas-liquid-solid reaction and efficient continuous separation of products.

Description

Technical Field

[0001] This invention relates to multiphase microreaction-separation systems and methods. Background Technology

[0002] The micro-interface fluid channel has a geometric size ranging from micrometers to 20 millimeters, a large specific surface area, high mass and heat transfer efficiency, low retention of hazardous media, short residence time, and almost no backmixing. It enhances heat transfer, and the large amount of heat generated by exothermic reactions can be quickly carried away by the temperature-controlled medium, keeping the reaction temperature close to isothermal and avoiding "runaway temperature" phenomena. The enhanced mass transfer process improves reaction efficiency, and reaction conditions are easy to control precisely. The reactor has a small liquid holdup, and even if an uncontrollable reaction occurs, it can still be intrinsically safe. It has been partially applied in many reactions such as nitration, chlorination, oxidation, and catalytic hydrogenation, and has achieved good results.

[0003] Membrane separation is a physical process that does not require phase changes or the addition of additives, and does not alter the original properties of substances. It features low energy consumption, ease of operation, and wide applicability, and can achieve efficient dynamic separation of solids and liquids. Summary of the Invention

[0004] The purpose of this invention is to couple a micro-interface reactor with a membrane separation system to achieve continuous separation of reaction products and to keep the solid catalyst circulating within the reaction system.

[0005] Traditional slurry bed reactors, also known as liquid slurry reactors, suffer from poor heat and mass transfer and struggle to eliminate localized overheating. Micro-interface reactors, with their enhanced reaction technology, can significantly optimize reaction conditions in chemical reactions. By substantially reducing reaction pressure and appropriately lowering reaction temperature, they can also multiply reaction rates, greatly reducing emissions, material consumption, energy consumption, and costs. However, since these are gas-liquid-solid three-phase or solid-liquid two-phase systems, it is necessary to address the separation of solid catalysts from products and to maintain the catalyst in circulation within the micro-interface reactor system.

[0006] The biggest drawback of the current microstructure of micro-interface reactors is that solid materials cannot pass through the microchannels. If there is a large amount of solid in the reaction medium, the microchannels are easily blocked, causing the reaction to be unable to proceed continuously.

[0007] The channel size of micro-interface reactors is mostly between 300μm and 1000μm, and the channel size of some industrially applied micro-interface reactors is in the millimeter range. When solid catalysts are introduced to mix gas, liquid and solid or liquid and liquid and solid for slurry-state reaction, the problem of solid catalyst clogging the channel needs to be solved. The technical challenges that need to be addressed by coupling micro-interface reaction systems with membrane separation include: 1) Introducing solid powder catalysts into the micro-interface reactor for recycling fully utilizes the excellent heat and mass transfer properties of the micro-interface reaction and solves the problem of solid catalyst clogging microchannels. Currently, the biggest drawback of the microstructure of the micro-interface reactor is that solid materials cannot pass through the microchannels. If there is a large amount of solid in the reaction medium (the solid catalyst content in this invention is ≤30%), the microchannels are easily clogged, causing the reaction to be unable to proceed continuously.

[0008] 2) Utilizing the highly efficient dynamic separation performance of membrane separation, the solid catalyst is intercepted and kept circulating in the micro-interface reaction system, while the reaction products are continuously separated. This invention preferably selects membrane separators made of materials resistant to the corrosion of the reaction medium, with ceramic membranes, metal membranes, or metal-ceramic composite membranes having an average pore diameter smaller than the average particle size of the solid catalyst. This effectively intercepts the solid catalyst in the cyclic reaction separation system coupled with the reactor and membrane separation, and separates the products from the membrane.

[0009] 3) The solid catalyst particles must have ultrafine, nano-sized particle sizes and be well dispersed in the reaction solution to avoid clogging the micro-interface reactor channels. In the design of the solid catalyst, this invention preferably selects materials with good dispersion performance in aqueous systems, low sedimentation rate, large specific surface area, and high activity to better adapt to the micro-interface reactor. A 2-30% mass content of this catalyst exhibits good continuous flow performance in the micro-interface reactor. 4) In the selection of micro-interface channels, this invention preferably chooses channels with a minimum size more than twice the average particle size of the solid catalyst to reduce dead zones prone to sedimentation and scaling, while retaining the enhanced mass and heat transfer characteristics of the micro-interface reactor.

[0010] This invention makes appropriate improvements to the micro-interface channel design. The minimum channel size is preferably more than twice the average particle size of the solid catalyst. The flow channel design reduces dead corners that are prone to sedimentation and scaling, while retaining the enhanced mass and heat transfer characteristics of the micro-interface reactor. This achieves uniform mixing of gas and liquid at the micro-nano scale, as well as uniform mixing of gas, liquid and solid phases, and stable operation.

[0011] This invention selects ceramic membranes, metal membranes, or metal-ceramic composite membranes with a precision matching the separation requirements caused by the average particle size of the solid catalyst, so as to ensure that the catalyst is not lost during the product separation process.

[0012] When selecting the circulation flow parameters, this invention takes as an important basis the requirement that the circulation flow rate simultaneously meets the flow rate requirements in the micro-interface reactor channel and the membrane surface flow rate. The reactants reach a fully turbulent state when passing through the micro-interface reactor and membrane separator. The material circulation flow rate of the micro-interface reactor and membrane separation coupling system is ≥2.0m / s.

[0013] According to a first aspect of the present invention, the present invention provides a multiphase microreaction-separation system, the system comprising: a micro-interface reaction unit, a membrane separation unit, and a circulation unit; wherein the micro-interface reaction unit is used to perform a gas-liquid-solid reaction; the circulation unit is used to receive a mixed slurry of a solid catalyst and a solvent and a circulating slurry from the micro-interface reaction unit and transport them to the membrane separation unit; the membrane separation unit is used to extract the reaction supernatant through membrane separation and transport the circulating slurry to the micro-interface reaction unit.

[0014] According to a second aspect of the present invention, a multiphase microreaction-separation method is provided, comprising: mixing a solid catalyst with a solvent to form a homogeneous slurry and adding it to a circulation unit; turning on a circulation slurry pump; passing the circulation slurry sequentially through a membrane separator and a micro-interface reactor, and returning it to a circulation tank to establish a closed-loop circulation contact reaction of the slurry; opening the liquid inlet and / or gas inlet valves of the micro-interface reactor, as well as the reaction clear liquid outlet valve and tail gas discharge valve of the membrane separator; the reaction mainly takes place in the micro-interface reactor, and the reaction products flow into a product tank with the membrane separation clear liquid; the solid catalyst is always kept in the circulation slurry for recycling due to the interception effect of the membrane separation.

[0015] The main technical problem solved by this invention is: 1) This invention is the first to couple the high-efficiency heat and mass transfer performance of a micro-interface reactor with the high-efficiency dynamic separation performance of a membrane, thereby achieving high-efficiency gas-liquid-solid reaction and high-efficiency continuous separation of products.

[0016] 2) Existing micro-interface reactors cannot achieve gas-liquid-solid reactions with the addition of solid catalysts because the channels of micro-interface reactors are very small. The channel size of micro-interface reactors is mostly between 300μm and 1000μm, and the channel size of some industrially applied micro-interface reactors is in the millimeter range. They are prone to clogging, and it is difficult to keep the solid catalyst in the reaction system.

[0017] 3) Traditional slurry bed reactors, also known as slurry reactors, and fixed bed reactors suffer from poor heat and mass transfer, making it difficult to solve local overheating problems. This hinders the safe and stable operation of hazardous processes such as nitration, chlorination, oxidation, and catalytic hydrogenation. Micro-interface reactors can transform hazardous processes into safer and more stable ones.

[0018] 4) The present invention uses membrane separation technology to achieve efficient dynamic separation of ultrafine and nanoparticles without phase change or the addition of additives. It can keep ultrafine and nano solid catalysts in the reaction system and achieve continuous separation and discharge of reaction products.

[0019] 5) This invention utilizes a micro-interface reactor, which allows for precise control of reaction temperature and shortens reaction time. The micro-interface reactor has an extremely large specific surface area, reaching hundreds or even thousands of times that of a stirred tank reactor. Microreactors possess excellent heat and mass transfer capabilities, enabling instantaneous and uniform mixing of materials and efficient heat transfer. Therefore, many reactions that cannot be achieved in conventional reactors can be realized in microreactors.

[0020] 6) The specific surface area of ​​the internal channels in micro-interface reactors is typically 10⁴ to 10⁶ m². 2 / m 3 The magnitude of the heat transfer is far greater than that of stirred tanks, pulse towers, and static mixers, and its mass and heat transfer performance has significant advantages over traditional reactors. The overall heat transfer coefficient of the micro heat exchanger can reach 56 kW / (m²). 2 The heat transfer efficiency (T / K) is approximately 20 times that of traditional plate heat exchangers, while the interphase volumetric mass transfer coefficient within the micro-interface device can reach 10 to 1000 times that of ordinary equipment. In terms of mixing and mass transfer, the mixing time of the micro-interface reactor can be as low as a few milliseconds, far less than that of traditional reactors, significantly reducing the impact of mass transfer on reaction time.

[0021] 7) The confined volume of micro-interface reactors can bring inherent safety. Within the confined volume of a micro-interface reactor, parameters such as temperature, pressure, residence time, and flow rate are controllable. For dangerous reaction systems such as rapid, strongly exothermic, and easily explosive reactions, micro-interface reactors can achieve process safety.

[0022] 8) Membrane separation can achieve the separation of solid catalysts with average particle size at the ultrafine and nanoscale, and the content of solid catalyst in the product can be controlled to ≤40ppm. Attached Figure Description

[0023] Figure 1 This is a process flow diagram according to one embodiment of the present invention; Figure 2 This is a front view of the membrane separation unit in operation according to an embodiment of the present invention; Figure 3 A plate-type micro-interface reactor according to one embodiment of the present invention; Figure 4 This is a tubular micro-interface reactor according to one embodiment of the present invention. Detailed Implementation

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in this specification shall prevail.

[0026] In the context of this specification, any two or more aspects of the present invention may be combined arbitrarily, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0027] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0028] To achieve the objectives of this invention, the present invention provides a multiphase microreaction-separation system, such as... Figure 1 As shown, the system includes a micro-interface reaction unit, a membrane separation unit, and a circulation unit. The micro-interface reaction unit is used for gas-liquid-solid or liquid-liquid-solid reactions. The circulation unit receives a slurry of solid catalyst and solvent, along with circulating slurry from the micro-interface reaction unit, and transports it to the membrane separation unit. The membrane separation unit separates the reaction liquid through a membrane and transports the circulating slurry back to the micro-interface reaction unit. This invention couples the high-efficiency heat and mass transfer performance of the micro-interface reactor with the high-efficiency dynamic separation performance of the membrane, achieving efficient gas-liquid-solid and liquid-liquid-solid reactions and efficient continuous product separation. Membrane separation technology maintains the concentration of the solid catalyst in the reaction system while simultaneously meeting the flow rate requirements for both reaction and separation, thus enhancing mass and heat transfer while avoiding clogging of the micro-interface reactor channels and membrane pores.

[0029] This invention effectively utilizes a micro-interface reactor to transform a hazardous process into a safe one, ensuring stable operation. Membrane separation technology enables highly efficient dynamic separation of ultrafine and nanoparticles without phase change or additives, allowing ultrafine and nanoparticle solid catalysts to be retained within the reaction system while simultaneously achieving continuous separation and discharge of reaction products.

[0030] Compared with traditional batch slurry bed and fixed bed reactions, it significantly reduces reaction pressure, avoids local overheating, and precisely controls reaction temperature, transforming a dangerous process into a safe one.

[0031] A micro-interface reactor refers to a reactor composed of a series of micro-interfaces with different geometric configurations manufactured by precision micromachining technology. The channel size is within micrometers or a few millimeters. This invention utilizes membrane separation technology to intercept and maintain the solid catalyst in the micro-interface membrane separation coupled reaction separation system, and realizes continuous dynamic separation of reaction liquid products. Through membrane separation, the catalyst content in the separated liquid products can be ≤40ppm.

[0032] Any system that meets the foregoing requirements can be used in this invention. Its specific structure can be adjusted according to actual production needs. The following is an illustrative description, but it does not limit the scope of this invention.

[0033] According to a preferred embodiment of the present invention, such as Figure 1 As shown, the circulation unit includes a circulation tank and a circulation slurry pump. The circulation tank includes a circulation slurry inlet, a mixed slurry inlet of solid catalyst and solvent, a gas outlet, and a circulation slurry outlet. The circulation slurry pump is located between the circulation slurry outlet pipeline and the feed pipeline of the membrane separation unit for pumping the circulation slurry to the membrane separation unit.

[0034] According to a preferred embodiment of the present invention, preferably, as follows: Figure 1 As shown, the circulating slurry inlet, the mixed slurry inlet of the solid catalyst and solvent, and the exhaust gas outlet are each located in the upper middle or top of the circulating tank.

[0035] According to a preferred embodiment of the present invention, preferably, as follows: Figure 1 As shown, the circulating slurry outlet is located at the bottom of the circulating tank.

[0036] According to a preferred embodiment of the present invention, preferably, as follows: Figure 1 As shown, the micro-interface reaction unit includes a micro-interface reactor and a gas phase inlet, a liquid phase inlet, a circulating slurry inlet, and a circulating slurry outlet disposed in the micro-interface reactor.

[0037] Figure 3 A plate-type micro-interface reactor according to one embodiment of the present invention is shown; it has the advantage of low flow rate.

[0038] Figure 4 A tubular micro-interface reactor according to one embodiment of the present invention is shown; it has the advantage of lower cost.

[0039] According to a preferred embodiment of the present invention, preferably, as follows: Figure 1 As shown, the circulating slurry outlet is located in the upper middle or top of the micro-interface reactor, while the gas phase inlet, liquid phase inlet, and circulating slurry inlet are each located in the lower middle or bottom of the micro-interface reactor.

[0040] In this invention, the characteristic size of the micro-interface reaction unit can be selected from a wide range, and is specifically determined according to the reaction type and catalyst selection. According to a preferred embodiment of this invention, preferably, the characteristic size of the micro-interface reaction unit is 300-20000 μm, and more preferably, the characteristic size of the micro-interface reaction unit is more than twice the average particle size of the solid catalyst.

[0041] The micro-interface reaction unit of the present invention has a feature size of 300 micrometers to 20 millimeters.

[0042] According to a preferred embodiment of the present invention, the membrane separation unit preferably includes a bottom circulating slurry inlet, a top circulating slurry outlet, and a side reaction clear liquid outlet.

[0043] According to a preferred embodiment of the present invention, preferably, the membrane separator of the membrane separation unit includes an outer wall of the membrane separator and a fluid channel surrounded by a membrane material arranged along the axial direction for circulating slurry inflow and outflow, and separating the reaction clear liquid through the membrane material.

[0044] Figure 2 A front view of the membrane separation unit in operation according to an embodiment of the present invention is shown.

[0045] In this invention, the membrane material has no special requirements. According to a preferred embodiment of the invention, the membrane material is preferably selected from ceramic membranes and / or metal membranes. The ceramic membranes, metal membranes, and metal-ceramic composite membranes selected in this invention are inorganic membrane materials with special selective separation functions. They can separate a fluid into two distinct parts, allowing one or more liquid reaction products to pass through the membrane and be separated, while the solid catalyst is retained in the slurry for continued recycling. Membrane separation utilizes the principle of mechanical sieving, using a pressure difference across the membrane as the driving force, and employing a cross-flow filtration method to achieve solid-liquid separation based on the size, shape, conformation, and polarity of the material molecules. The core of membrane separation is the membrane itself; the membrane pores act as a sieving mechanism, allowing the slurry containing solid catalyst larger than the pore size to pass through the membrane tube and continue circulating to the reactor. The liquid products and some solvent produced by the reaction pass through the membrane pores as a clear liquid. The clear liquid flowing into the product tank can be separated and purified to obtain a qualified product.

[0046] According to a preferred embodiment of the present invention, the average diameter of the membrane pores in the membrane separation is smaller than the average particle size of the solid particles.

[0047] According to a preferred embodiment of the present invention, the system further includes a product tank for collecting the reaction solution extracted by the membrane separation unit.

[0048] This invention provides a multiphase microreaction-separation method, the method comprising: After the solid catalyst and solvent are mixed into a homogeneous slurry, it is added to the circulation unit. The inlet valve of the slurry mixture of solid catalyst and solvent and the outlet valve of the membrane separator are closed. The circulation slurry pump is turned on. The circulation slurry passes through the membrane separator and the micro-interface reactor in sequence and returns to the circulation tank, establishing a closed-loop circulation contact reaction of the slurry. The liquid phase inlet and / or gas phase inlet valve of the micro-interface reactor, as well as the reaction clear liquid outlet valve and tail gas exhaust valve of the membrane separator are opened. The reaction mainly takes place in the micro-interface reactor. The reaction products flow into the product tank with the membrane separation clear liquid. The product tank is discharged in time to achieve continuous reaction. The material discharged from the product tank maintains a material balance with the liquid phase feed and / or gas phase feed; the solid catalyst is always kept in the circulating slurry for recycling through the interception effect of membrane separation. When partially deactivated, the catalyst slurry is replenished from the inlet of the circulating tank, and after complete deactivation, the catalyst is discharged and replaced.

[0049] According to a preferred embodiment of the present invention, the reactants are in a turbulent or fully turbulent state when passing through the micro-interface reactor and membrane separator, and the flow velocity of the circulating slurry is ≥1.0 m / s, preferably ≥2.0 m / s, and more preferably 5-20 m / s.

[0050] According to a preferred embodiment of the present invention, the average diameter of the membrane pores in the membrane separation is smaller than the average particle size of the solid catalyst; preferably, the average diameter of the membrane pores in the membrane separation is less than 200 nm, more preferably 200-300 nm, and the average particle size of the solid catalyst is greater than 200 nm, more preferably 300-600 nm.

[0051] According to a preferred embodiment of the present invention, the solid catalyst comprises a molecular sieve composed of Ti, Si, Al, and O, and has an MFI topology, with a specific surface area of ​​350 m² in the solid state. 2 / g) or more, preferably 950-1500 (m) 2 / g).

[0052] According to a preferred embodiment of the present invention, more preferably, the average pore size of the solid catalyst is 0.45-0.75 nm.

[0053] Solid catalysts having the aforementioned characteristics of this invention can all be used in this invention, and there are no special requirements for their preparation methods. The following is an illustrative description, but it does not limit the scope of this invention.

[0054] According to a preferred embodiment of the present invention, preferably, the solid catalyst is a titanium-silicon molecular sieve (TS-1) obtained by surfactant treatment.

[0055] According to a preferred embodiment of the present invention, more preferably, the method for preparing the solid catalyst includes contacting a titanium-silicon molecular sieve with an aqueous solution of a surfactant.

[0056] In this invention, the range of contact conditions is relatively wide. The following is an illustrative description, but it does not limit the scope of the invention. For this invention, the preferred contact conditions include a temperature of 20-90°C, preferably 30-80°C.

[0057] In this invention, the contact conditions can be selected from a wide range, especially the contact time, which can be specifically selected. The following is an illustrative description, but it does not limit the scope of the invention. For this invention, the preferred contact conditions include a time of 0.5-5 hours, preferably 0.5-2 hours.

[0058] In this invention, the concentration of the surfactant aqueous solution can be selected over a wide range. The following is an illustrative description, but it does not limit the scope of the invention. For this invention, the preferred surfactant aqueous solution concentration is 0.1-20 wt%, more preferably 1-10 wt%. The weight ratio of the titanium silicate molecular sieve to the surfactant aqueous solution is 1:10-500, preferably 1:10-60; and / or In this invention, various titanium-silicon molecular sieves can be used. The following is an illustrative description, but it does not limit the scope of the invention. For the purposes of this invention, the titanium-silicon molecular sieve is preferably one or more of TS-1, TS-2 and HTS.

[0059] In this invention, various surfactants can be used. The following is an illustrative description, but it does not limit the scope of the invention. For the purposes of this invention, the surfactant is preferably selected from one or more combinations of anionic, cationic and nonionic surfactants.

[0060] The range of anionic, cationic, and nonionic surfactants that can be selected is quite wide. The following is an example, but it does not limit the scope of the present invention.

[0061] In this invention, preferably, the anionic surfactant used is selected from one or more of alkylbenzene sulfonates, alkyl sulfonate salts, and alkyl sulfonates, for example, sodium dodecylbenzene sulfonate.

[0062] In this invention, preferably, the cationic surfactant used is selected from one or more of hexadecyltrimethylammonium chloride and octadecyltrimethylammonium chloride.

[0063] In this invention, preferably, the nonionic surfactant used is selected from one or more of fatty alcohol polyoxyethylene ether, alkylolamide, polyol monofatty acid ester, alkylamine oxide, and N-alkylpyrrolidone, for example, sorbitan monostearate and / or octadecyl polyoxyethylene ether.

[0064] The multi-level porous multifunctional molecular sieve catalyst proposed in this invention has the characteristics of good dispersion in aqueous systems, low sedimentation, large specific surface area, and good activity. It exhibits good performance when continuously passed through a micro-interface reactor at a mass content of 2-10%. The system and reaction described in this invention are applicable to a variety of reactions, and are particularly suitable for various oxidation and peroxidation reactions.

[0065] In this invention, the reaction raw materials are determined according to the specific reaction type, and the reaction raw materials are either liquid-liquid reaction raw materials or gas-liquid reaction raw materials.

[0066] In this invention, the composition of the gas-phase reaction raw materials is determined according to the specific reaction type. When it is an oxidation reaction or a peroxidation reaction, the gas-liquid reaction raw materials include the oxide to be oxidized and the oxidant. The oxide to be oxidized is selected from one or more of gaseous aromatics, gaseous alkanes, and gaseous alkenes.

[0067] In this invention, the oxidant is selected from oxygen-containing liquid phase substances, such as hydrogen peroxide.

[0068] According to one embodiment of the present invention, preferably, the gas-liquid reaction raw materials include: ethylene and hydrogen peroxide.

[0069] In this invention, the contact reaction conditions in the micro-interface reactor are determined based on the specific reaction. The following is an illustrative description, but it does not limit the scope of the invention.

[0070] According to one embodiment of the present invention, preferably, the contact reaction conditions in the micro-interface reactor include: a catalyst to solvent mass ratio of 1~30:100, a reaction temperature of 25~90℃, preferably 40~60℃; and a reactor inlet pressure of 0.2~2.0MPa(G). According to one embodiment of the present invention, preferably, more preferably, when the gas-liquid reaction raw materials include ethylene and hydrogen peroxide, the conditions for the contact reaction in the micro-interface reactor include: a mass ratio of catalyst to solvent of 5~20:100, a reaction temperature of 25~90℃, and a reactor inlet pressure of 0.2~2.0MPa (G).

[0071] The reaction separation method of the present invention is suitable for the one-step oxidation of ethylene to ethylene glycol, and the specific steps are as follows: Ethylene is fed in the gas phase, hydrogen peroxide in the liquid phase, and a bifunctional oxidative hydration catalyst is fed in the solid phase. The solid catalyst and solvent are mixed uniformly in a specific ratio and then added to a circulating tank. The catalyst mass concentration is 0.5-30%, the reaction temperature is 25-90℃, and the reactor inlet pressure is 0.2-1.0 MPa(G). Ethylene and hydrogen peroxide are continuously fed. The solid catalyst is kept in the system for recycling through membrane separation. The liquid product containing ethylene glycol is continuously discharged, and further separation and purification yield qualified ethylene glycol.

[0072] Test Example 1: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol After the solid catalyst and solvent are mixed into a homogeneous slurry, it is added to the circulation unit. The inlet valve of the slurry mixture of solid catalyst and solvent and the outlet valve of the membrane separator are closed. The circulation slurry pump is turned on. The circulation slurry passes through the membrane separator and the micro-interface reactor in sequence and returns to the circulation tank, establishing a closed-loop circulation contact reaction of the slurry. The liquid phase inlet and gas phase inlet valves of the micro-interface reactor, as well as the reaction clear liquid outlet valve and tail gas outlet valve of the membrane separator are opened. The reaction mainly takes place in the micro-interface reactor. The reaction products flow into the product tank with the membrane separation clear liquid. The product tank is discharged in time to achieve continuous reaction. The material discharged from the product tank maintains a material balance with the liquid and gas phase feeds; the solid catalyst is kept in the circulating slurry for continuous use through the interception effect of membrane separation. When partially deactivated, the catalyst slurry is replenished from the inlet of the circulating tank, and after complete deactivation, the catalyst is discharged and replaced.

[0073] Membrane separation uses metal membranes, and the workflow is as follows: Figure 2 As shown, the membrane pore diameter is 200 nm; The micro-interface reactor adopts the diagram Figure 3 The plate-type micro-interface reactor shown has a characteristic size of 300-15000 μm; Ethylene is fed in the gas phase, hydrogen peroxide in the liquid phase, and an oxidation-hydration bifunctional catalyst in the solid phase. The catalyst and solvent water are mixed uniformly at a ratio of 0.5~30:100 and then added to a circulation tank. The flow rate of the circulating slurry is ≥2.0 m / s. The catalyst mass concentration in the liquid phase is 0.5~30%, the reaction temperature is 25~90℃, and the reactor inlet pressure is 0.2~1.0 MPa(G). Ethylene and hydrogen peroxide are continuously fed into the micro-interface reactor. The minimum diameter of the microchannel is ≥1 mm. The solid catalyst is intercepted and retained in the system for recycling through membrane separation with an average pore size ≤300 nm. The liquid product containing ethylene glycol is continuously discharged. After further separation and purification, qualified ethylene glycol product is obtained with a yield ≥90% and a selectivity ≥90%.

[0074] The multi-level porous bifunctional molecular sieve catalyst used in this invention has the characteristics of good dispersion performance in water systems, not easy to settle, large specific surface area and good activity, and outstanding effect in micro-interface reactors.

[0075] This invention studies the process conditions for the one-step direct oxidation of ethylene to ethylene glycol, achieving continuous and stable feeding and discharging operation of the gas, liquid, and solid three-phase continuous flow reaction separation system, with ethylene glycol selectivity ≥90% and hydrogen peroxide conversion rate ≥90%.

[0076] The one-step hydrogen peroxide oxidation of ethylene to ethylene glycol in this invention is achieved under low-temperature and mild conditions of 25~90℃, which is a risk-free Class I safety reaction. It is expected to replace the dangerous process of ethylene oxide production in the existing ethylene glycol process and achieve inherent safety in the production process.

[0077] This invention achieves low-temperature oxidation of ethylene, with no greenhouse gas CO2 produced during the reaction, thus realizing inherent environmental protection. Existing processes involve high-temperature oxidation, in which approximately 15% of the ethylene is oxidized into CO2 emissions.

[0078] This invention requires no additional water beyond the initial catalyst preparation and the water already contained in hydrogen peroxide. Existing ethylene glycol hydration requires the addition of 10 to 30 times the amount of water. The new process significantly reduces energy consumption and emissions, achieving energy saving and emission reduction.

[0079] To facilitate understanding of the present invention, embodiments are provided below. However, those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as specific limitations on the invention. The endpoints of the ranges and any values ​​disclosed herein are not limited to those precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them.

[0080] The titanium-silicon molecular sieve (TS-1) used in the following preparation examples has a specific surface area of ​​316 μm. 2 / g, with an average particle size of 500nm and an average pore size of 0.53nm, were commercially purchased from Hunan Jianchang Petrochemical Co., Ltd.

[0081] Preparation Example 1 A catalyst can be prepared by stirring 10g of titanium silicate molecular sieve (TS-1), 100g of water, and 2g of sodium dodecylbenzenesulfonate (anionic surfactant) at 60°C for 1 hour. The catalyst has a specific surface area of ​​1032m. 2 / g, average pore size 0.62nm.

[0082] Preparation Example 2 A catalyst with a specific surface area of ​​1049 μm can be prepared by stirring 10 g of titanium silicate molecular sieve (TS-1), 500 g of water, and 20 g of cationic surfactant hexadecyltrimethylammonium chloride at 30 °C for 5 hours. 2 / g, average pore size 0.65nm.

[0083] Preparation Example 3 10g of titanium silicate molecular sieve (TS-1), 300g of water, 15g of nonionic surfactant sorbitan monostearate (Spinol 60), and 15g of polyoxyethylene (20) sorbitan monostearate (Tween 60) are stirred at 80℃ for 0.5 hours to produce a catalyst with a specific surface area of ​​1424m. 2 / g, average pore size 0.68nm.

[0084] Preparation Example 4 10 grams of titanium-silicon molecular sieve (TS-1), 200 grams of water, using linear alkyl polyoxyethylene ethers such as octadecyl polyoxyethylene ether (C 18 EO 10 20 grams, stirred at 70℃ for 1.5 hours, yielded a specific surface area of ​​993 m². 2 / g, average pore size 0.59nm.

[0085] Example 1: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The catalyst of Preparation Example 1 was used in accordance with the method of Test Example 1.

[0086] The micro-interface reactor has a characteristic size of 300 μm, a pore diameter of 200 nm for the metal membrane, a molar ratio of ethylene to hydrogen peroxide of 1.2:1, a weight ratio of catalyst to water solvent of 10:100, a reaction temperature of 40 °C, an inlet pressure of 0.5 MPa (G), a circulating slurry flow rate of 10 m / s, and a continuous discharge of liquid product containing ethylene glycol. After further separation and purification, qualified ethylene glycol product is obtained with an ethylene glycol yield of 90% and an ethylene glycol selectivity of 94%.

[0087] Example 2: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The catalyst of Preparation Example 2 was used in accordance with the method of Test Example 1.

[0088] The micro-interface reactor has a characteristic size of 15000 μm, a pore diameter of 200 nm for the metal membrane, a molar ratio of ethylene to hydrogen peroxide of 1.5:1, a catalyst to water solvent ratio of 5:100, a reaction temperature of 60 °C, an inlet pressure of 1 MPa (G), a circulating slurry flow rate of 5 m / s, and a continuous discharge of liquid product containing ethylene glycol. After further separation and purification, qualified ethylene glycol product is obtained with an ethylene glycol yield of 91% and an ethylene glycol selectivity of 92%.

[0089] Example 3: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The catalyst of Preparation Example 2 was used in accordance with the method of Test Example 1.

[0090] The micro-interface reactor has a characteristic size of 1000 μm, a pore diameter of 300 nm for the metal membrane, a molar ratio of ethylene to hydrogen peroxide of 1:1, a mass ratio of catalyst to water solvent of 20:100, a reaction temperature of 50 °C, an inlet pressure of 0.2 MPa (G), a circulating slurry flow rate of 20 m / s, and a continuous discharge of liquid product containing ethylene glycol. After further separation and purification, qualified ethylene glycol product is obtained with an ethylene glycol yield of 89% and an ethylene glycol selectivity of 91%.

[0091] Example 4: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The method of Example 3 was followed, except that the catalyst of Preparation Example 4 was used. The ethylene glycol yield was 89%, and the ethylene glycol selectivity was 92%.

[0092] As shown in the results of Examples 1-4, the method of this invention, using the multiphase microreaction-separation system of this invention, can significantly improve the efficiency of reaction mass and heat transfer, accelerate the reaction rate, maintain a high reaction rate at low temperature and low pressure, and achieve high selectivity and high yield of gas-liquid-solid three-phase reaction. Secondly, the multiphase microreaction-separation system of this invention can achieve efficient dynamic separation of ultrafine and nanoparticles, and the reaction products can be continuously and rapidly separated and discharged over a long period. Simultaneously, by combining the control of catalyst dispersion performance with the structural design of the reaction-separation system, excellent throughput performance with high solid content can be achieved. After 3000 hours of system operation, the system still operates stably, with no agglomeration or sedimentation of solids in the channels, and no system blockage. Moreover, the preferred catalyst still exhibits good dispersibility and high activity.

[0093] Example 5: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The method is the same as in Example 1, except that the catalyst used is a titanium silicate molecular sieve (TS-1) with a specific surface area of ​​433 μm. 2 / g. Ethylene glycol yield was 60%, and ethylene glycol selectivity was 79%.

[0094] Comparative Example 1: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The reaction was carried out using a batch reactor, with the catalyst and feed as in Example 1. The molar ratio of ethylene to hydrogen peroxide was 1.2:1, the ratio of catalyst to water solvent was 10:100, the reaction temperature was 40°C, and the inlet pressure was 0.5 MPa (G). After 3 hours of reaction, the ethylene glycol yield was 75%, and the ethylene glycol selectivity was 83%.

[0095] Comparative Example 2: One-step direct oxidation of ethylene with hydrogen peroxide to produce ethylene glycol The reaction was carried out using a fixed bed reactor, with the same catalyst and feed as in Example 1. The molar ratio of ethylene to hydrogen peroxide was 2:1, the ratio of catalyst to water solvent was 10:100, the reaction temperature was 40°C, and the inlet pressure was 0.5 MPa (G). After 1.5 h of reaction, the ethylene glycol yield was 48%, and the ethylene glycol selectivity was 73%.

[0096] The results of the comparative examples and embodiments described above demonstrate that other multiphase reactors, under low-temperature and low-pressure reaction conditions, exhibit poor three-phase mixing, low mass transfer efficiency, and insufficient contact between the raw materials and the catalyst, resulting in low selectivity and yield of the target product and the generation of numerous byproducts. In contrast, this invention significantly improves the efficiency of mass and heat transfer, ensuring thorough mixing of the raw materials and rapid contact with the active sites of the catalyst, thereby maintaining high reaction selectivity, conversion, and yield under low temperature and low pressure conditions.

[0097] The embodiments described above are merely illustrative of the detailed process of the present invention, but the present invention is not limited to the above-described process; that is, the present invention can be implemented without relying on the steps described in the above embodiments. In summary, any improvements made to the present invention by those skilled in the art, including substitutions for the raw materials and additives described in the present invention, and selections of specific implementation methods, are all within the scope of protection and disclosure of the present invention.

Claims

1. A multiphase microreaction-separation system, characterized in that The system includes: a micro-interface reaction unit, a membrane separation unit, and a circulation unit. in, The micro-interface reaction unit is used to carry out gas-liquid-solid reactions; The circulation unit is used to receive the mixed slurry of solid catalyst and solvent and the circulating slurry from the micro-interface reaction unit and transport it to the membrane separation unit; The membrane separation unit is used to extract the reaction supernatant through membrane separation and to transport the circulating slurry to the micro-interface reaction unit.

2. The system of claim 1, wherein, The circulation unit includes a circulation tank and a circulation slurry pump. The circulation tank includes a circulation slurry inlet, a mixed slurry inlet of solid catalyst and solvent, a gas outlet, and a circulation slurry outlet. The circulation slurry pump is located between the circulation slurry outlet pipeline and the feed pipeline of the membrane separation unit for pumping the circulation slurry to the membrane separation unit. Preferably, the circulating slurry inlet, the mixed slurry inlet of the solid catalyst and solvent, and the exhaust gas outlet are each located in the upper middle or top of the circulating tank; Preferably, the circulating slurry outlet is located at the bottom of the circulating tank.

3. The system of claim 1 or 2, wherein, The micro-interface reaction unit includes a micro-interface reactor and a gas phase inlet, a liquid phase inlet, a circulating slurry inlet, and a circulating slurry outlet disposed in the micro-interface reactor. Preferably, the circulating slurry outlet is located in the upper middle or top of the micro-interface reactor, and the gas phase inlet, liquid phase inlet, and circulating slurry inlet are each located in the lower middle or bottom of the micro-interface reactor. Preferably, the characteristic size of the micro-interface reaction unit is 300 micrometers to 20 millimeters, and more preferably, the characteristic size of the micro-interface reaction unit is more than twice the average particle size of the solid catalyst.

4. The system of any of claims 1-3, wherein, The membrane separation unit includes a bottom circulating slurry inlet, a top circulating slurry outlet, and a side reaction clear liquid outlet; The membrane separator of the membrane separation unit includes an outer wall of the membrane separator and a fluid channel surrounded by membrane material arranged along the axial direction for circulating slurry inflow and outflow, and for separating the reaction clear liquid through the membrane material; Preferably, the membrane material is selected from ceramic membranes and / or metal membranes and / or metal-ceramic composite membranes; Preferably, the average diameter of the membrane pores in the membrane separation is smaller than the average particle size of the solid particles; and / or The system also includes a product tank for collecting the reaction solution extracted from the membrane separation unit.

5. A multiphase microreactive-separation process characterized by, The method includes: After the solid catalyst and solvent are mixed into a homogeneous slurry, it is added to the circulation unit. The inlet valve of the slurry mixture of solid catalyst and solvent and the outlet valve of the membrane separator are closed. The circulation slurry pump is turned on. The circulation slurry passes through the membrane separator and the micro-interface reactor in sequence and returns to the circulation tank, establishing a closed-loop circulation contact reaction of the slurry. The liquid phase inlet and / or gas phase inlet valve of the micro-interface reactor, as well as the reaction clear liquid outlet valve and tail gas exhaust valve of the membrane separator are opened. The reaction mainly takes place in the micro-interface reactor. The reaction products flow into the product tank with the membrane separation clear liquid. The product tank is discharged in time to achieve continuous reaction. The material discharged from the product tank maintains a material balance with the liquid phase feed and / or gas phase feed; the solid catalyst is always kept in the circulating slurry for recycling through the interception effect of membrane separation. When partially deactivated, the catalyst slurry is replenished from the inlet of the circulating tank, and after complete deactivation, the catalyst is discharged and replaced.

6. The method of claim 5, wherein, When the reactants pass through the micro-interface reactor and membrane separator, they reach a turbulent or fully turbulent state. The flow velocity of the circulating slurry is ≥1.0 m / s, preferably ≥2.0 m / s, and more preferably 5-20 m / s.

7. The method of claim 5 or 6, wherein, The average diameter of the membrane pores in the membrane separation is smaller than the average particle size of the solid catalyst; preferably, the average diameter of the membrane pores in the membrane separation is below 200 nm, more preferably 200-300 nm; the average particle size of the solid catalyst is greater than 200 nm, more preferably 300-600 nm.

8. The method according to any one of claims 5-7, wherein, The solid catalyst composition comprises: a molecular sieve composed of Ti, Si, Al, O and having an MFI topological structure, a specific surface area of 350 (m 2 / g) or more, preferably 950-1500 (m 2 / g) in a solid state; More preferably, the solid catalyst has an average pore size of 0.45-0.75 nm; Preferably, the solid catalyst is obtained by treating titanium silicate molecular sieve (TS-1) with a surfactant. More preferably, the method for preparing the solid catalyst includes: contacting a titanium-silicon molecular sieve with an aqueous solution of a surfactant, wherein the contact conditions include: The temperature is 20-90℃, preferably 30-80℃; and / or The time is 0.5-5 hours, preferably 0.5-2 hours; and / or The concentration of the surfactant aqueous solution is 0.1-20 wt%, preferably 1-10 wt%; and / or The weight ratio of titanium silicate molecular sieve to surfactant aqueous solution is 1:10-500, preferably 1:10-60; and / or The titanium-silicon molecular sieve is one or more of TS-1, TS-2, and HTS; and / or The surfactant is selected from one or more combinations of anionic, cationic, and nonionic surfactants; Preferably, the anionic surfactant used is selected from one or more of alkylbenzene sulfonates, alkyl sulfonate salts, and alkyl sulfonates, and is preferably sodium dodecylbenzene sulfonate; Preferably, the cationic surfactant used is selected from one or more of hexadecyltrimethylammonium chloride and octadecyltrimethylammonium chloride; Preferably, the nonionic surfactant used is selected from one or more of fatty alcohol polyoxyethylene ether, alkylolamide, polyol monofatty acid ester, alkylamine oxide, and N-alkylpyrrolidone, and is more preferably sorbitan monostearate and / or octadecyl polyoxyethylene ether.

9. The method according to any one of claims 5-8, wherein, The types of contact reactions include one or more of the following: oxidation reaction and peroxidation reaction; Preferably, the reaction raw materials are gas-liquid reaction raw materials; The gas-liquid reaction feedstock includes an oxide to be oxidized and an oxidant, wherein the oxide to be oxidized is selected from one or more of gaseous aromatics, gaseous alkanes, and gaseous alkenes; The oxidant includes hydrogen peroxide; Preferably, the gas-liquid reaction raw materials include: ethylene and hydrogen peroxide.

10. The method according to any one of claims 5-9, wherein, In the micro-interface reactor, the contact reaction conditions include: a catalyst to solvent mass ratio of 1~30:100; a reaction temperature of 25~90℃, preferably 40~60℃; and a reactor inlet pressure of 0.2~2MPa(G). More preferably, when the gas-liquid reaction feedstock includes ethylene and hydrogen peroxide, the conditions for the contact reaction in the micro-interface reactor include: a catalyst to solvent mass ratio of 5~20:100, a reaction temperature of 25~90℃, preferably 40~60℃, and a reactor inlet pressure of 0.2~2.0MPa(G).

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