Photocatalytic reaction system and photocatalytic reaction method for reducing CO2 / N2 through water vapor

Abstract

The invention provides a photocatalytic reaction system and a photocatalytic reaction method. According to the photocatalytic reaction device system and the reaction method, the structure is simple, the automation degree is high, CO2 / N2 reduction reaction can be driven under the efficient coupling photo-thermal condition, the light-transmitting reaction coil serves as a reaction tube pass, a temperature control pipeline is designed in a reactor shell layer, and according to the temperature distribution of the reactor, the reaction temperature can be controlled. The working states of different temperature control pipelines are modulated, so that the reactor is uniformly heated, and the problems of reaction tube pass blocking, incident light path change, catalyst deactivation and the like caused by local water condensation are effectively solved. The reaction system provided by the invention also fully utilizes the raw material water to exchange heat with the reaction product, and meanwhile, the energy consumption for separating the product and heating the raw material water is reduced. In addition, the water consumption of the process can be greatly reduced by recycling the condensate water.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalytic water vapor reduction of CO2 / N2, and relates to a photocatalytic reaction system and a photocatalytic reaction method, and in particular to a photocatalytic reaction system and a photocatalytic reaction method for reducing CO2 / N2 with water vapor. Background Art

[0002] Through photosynthesis, nature converts CO2 and water in the air into organic matter and converts solar energy into chemical energy. It can be said that photosynthesis provides the basis for human survival and development. At the same time, there are some nitrogen-fixing microorganisms in nature that can reduce nitrogen to ammonia under mild conditions, which constitutes one of the main nitrogen sources in the nitrogen cycle in the biosphere. By simulating photosynthesis and biological nitrogen fixation reactions in nature, converting CO2 / N2 molecules and water into hydrocarbon fuels and ammonia that is needed in large quantities in industry and agriculture is a feasible strategy for converting and utilizing solar energy. At present, H2 or CH4 is usually used as a reducing agent for CO2 / N2 molecules in industry, such as using CO2 to produce methanol and synthesis gas. The synthesis of ammonia by nitrogen fixation reaction is also a common industrial synthesis process. For example, the Haber-Bosch method used in industry can use iron catalysts to convert N2 and H2 into ammonia. Although these chemical processes are currently based on traditional thermal catalysis, and some are relatively mature, the specific reaction conditions are usually harsh and accompanied by great energy consumption. For example, the reaction temperature of CO2 to methanol ranges from 250 to 350°C and the pressure ranges from 20 to 30 MPa; the reaction temperature of CH4 dry reforming with CO2 ranges from 750 to 800°C; and the Haber-Bosch method also requires a high temperature of more than 300°C and a pressure of more than 100 atmospheres. At the same time, the efficient and safe transportation of H2 also requires additional technical support.

[0003] Therefore, in recent years, researchers have focused on using water, one of the most common substances on earth, as a raw material to develop a series of photocatalytic systems that use water as a reducing agent to reduce CO2 / N2 molecules under mild sunlight conditions. However, the current photocatalytic reaction route for reducing CO2 / N2 with water vapor is still immature, which easily leads to problems such as energy waste, difficulty in controlling the reaction process, and low light utilization.

[0004] Therefore, how to design a more suitable photocatalytic reaction mode to solve the above-mentioned problems existing in the current photocatalytic reaction process of water vapor reduction of CO2 / N2 has become one of the technical problems that many forward-looking researchers in this technical field need to solve urgently. Summary of the invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a photocatalytic reaction system and a photocatalytic reaction method, in particular, a photocatalytic reaction system for reducing CO2 / N2 using water vapor. The present invention adopts a light-transmitting reaction coil and evenly distributes a temperature control pipeline in the reactor shell, thereby controlling the temperature distribution of the system and modulating the working state of the temperature control pipeline, thereby achieving uniform temperature control of the reactor, thereby avoiding problems such as obstruction of the reaction tube caused by condensation of water in the reaction raw materials, change of the incident light path, and deactivation of the catalyst.

[0006] The present invention provides a photocatalytic reaction system, which comprises:

[0007] Photocatalytic reactor;

[0008] a heat exchanger connected to the reactor;

[0009] a quench cooler connected to the heat exchanger;

[0010] a gas separation device connected to the quench cooler;

[0011] a boiling evaporator connected to the reactor and the heat exchanger respectively;

[0012] The photocatalytic reactor comprises a light-transmitting reaction coil and a photoreaction catalyst arranged on the inner wall of the light-transmitting reaction coil;

[0013] One end of the light-transmitting reaction coil is a reaction raw material inlet, and the other end is a reaction product outlet.

[0014] Preferably, a transparent panel is provided on the light-transmitting reaction coil;

[0015] The material of the transparent panel includes one or more of transparent glass, quartz glass, organic glass and ZnSe glass;

[0016] A temperature control pipeline is arranged around the light-transmitting reaction coil;

[0017] The temperature control pipeline is specifically a temperature control pipeline for realizing the overall and / or segmented temperature control of the light-transmitting reaction coil;

[0018] The photoreaction catalyst is specifically a photoreaction CO2 / N2 reduction catalyst.

[0019] Preferably, the photoreaction catalyst comprises one or more of a metal nanocatalyst, a semiconductor nanocatalyst or a composite catalyst;

[0020] The heat exchanger includes one or more of a shell-and-tube heat exchanger, a jacketed heat exchanger, a coiled tube heat exchanger and a shell-and-tube heat exchanger;

[0021] The heat medium inlet of the heat exchanger is connected to the reaction product outlet;

[0022] The heat medium outlet of the heat exchanger is connected to the heat medium inlet of the quench cooler.

[0023] Preferably, the cold medium inlet of the heat exchanger is connected to the water source;

[0024] The cold medium outlet of the heat exchanger is connected to the inlet of the boiling evaporator through a first pipeline;

[0025] The heat exchanger is provided with a condensate outlet;

[0026] The condensate outlet is communicated with the first pipeline.

[0027] Preferably, the quench cooler comprises a partition heat exchanger;

[0028] The gas separation device includes one or more of a cryogenic liquefaction separation device, a pressure swing adsorption device and a membrane separation device;

[0029] The hot medium outlet of the quench cooler is connected to the inlet of the gas separation device through a second pipeline;

[0030] The second pipeline is provided with a temperature and / or pressure sensor.

[0031] Preferably, the heating method of the boiling evaporator includes one or more of external heating, partition heating and electric heating tube heating;

[0032] The boiling evaporator includes one or more of a liquid storage boiling evaporator, a spray boiling evaporator and a thin film boiling evaporator;

[0033] The reaction raw material inlet of the photocatalytic reactor is connected to the feed pipeline;

[0034] The outlet of the boiling evaporator is connected to the feed pipeline through a third pipeline.

[0035] Preferably, the photocatalytic reaction system further comprises one or more of a light source, a control system, an auxiliary control device and a sensor system;

[0036] The auxiliary control device includes a flow control valve;

[0037] The sensing system includes a temperature sensor and / or a pressure sensor;

[0038] A flow control valve is provided at one or more of the feed pipeline, the first pipeline connecting the heat exchanger and the boiling evaporator, the third pipeline, the cold medium inlet of the quench cooler and the cold medium outlet of the quench cooler;

[0039] The control system realizes steady-state interlocking regulation by associating one or more of the auxiliary control device, the sensor system and the devices in the system.

[0040] The present invention provides a photocatalytic reaction method using the photocatalytic reaction system described in any one of the above technical solutions, comprising the following steps:

[0041] 1) The raw water is subjected to heat exchange and then boiled and evaporated to obtain water vapor;

[0042] 2) mixing the water vapor obtained in the above step with CO2 and / or N2 gas, and then feeding the mixture into a photocatalytic reactor, and performing a photocatalytic reaction under the action of incident light from a light source and a photocatalyst to obtain a reaction product;

[0043] 3) subjecting the reaction product obtained in the above steps to heat exchange and cooling, separation of water and / or part of the reaction product, and further gas separation to obtain a final product;

[0044] The heat exchange in step 3) is carried out with the raw water in step 1).

[0045] Preferably, the boiling evaporation pressure is 0.1-20 MPa;

[0046] The temperature after boiling and evaporation is 80-200°C;

[0047] The pressure of the photocatalytic reaction is 0.1-10 MPa;

[0048] The pressure of the photocatalytic reaction is not higher than the pressure of the boiling evaporation;

[0049] The light source includes one or more of sunlight, a xenon lamp, an LED lamp, a tungsten halogen lamp, a mercury lamp and an infrared lamp.

[0050] Preferably, the incident light intensity is 5 to 4000 mW / cm 2 ;

[0051] The photocatalyst includes a carrier-composite photocatalyst;

[0052] The carrier includes one or more of a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer and quartz glass;

[0053] The reaction products in step 2) include one or more of CH4, CO and NH3, and O2;

[0054] After the gas is separated, two final products are obtained, one is O2 and the other is CH4 and / or CO.

[0055] The present invention provides a photocatalytic reaction system, the photocatalytic reaction system comprising: a photocatalytic reactor; a heat exchanger connected to the reactor; a quencher connected to the heat exchanger; a gas separation device connected to the quencher; a boiling evaporator connected to the reactor and the heat exchanger respectively; the photocatalytic reactor comprises a light-transmitting reaction coil and a photoreaction catalyst arranged on the inner wall of the light-transmitting reaction coil; one end of the light-transmitting reaction coil is a reaction raw material inlet, and the other end is a reaction product outlet. Compared with the prior art, the present invention aims at the problems of energy waste, difficult reaction process control, low light utilization rate, etc. in the existing photocatalytic reaction process of water vapor reducing CO2 / N2. The research believes that one of the reasons for the above problems is that the high specific heat capacity of water and the easy condensation of water vapor on the light window are one of the reasons for the above problems.

[0056] Based on this, the present invention specially designs a photocatalytic reaction system for reducing CO2 / N2 with water vapor having a specific structure. The device system includes a reaction system, a sensing system, an auxiliary system and a control system. By using a light-transmitting reaction coil with a photoreaction catalyst arranged on the inner wall as the reaction area, and evenly distributing the temperature control pipeline in the shell of the reactor relative to the tube, the temperature distribution of the reactor is monitored in real time by the control system, and the working state of the temperature control pipeline is modulated, thereby achieving uniform temperature control of the reactor, and avoiding the problems of the reaction tube being blocked, the incident light path being changed, and the catalyst being deactivated due to the condensation of water in the reaction raw materials. Further, in the reaction system provided by the present invention, the reaction product is first allowed to enter the heat exchanger for heat exchange with the raw water, and then enter the quencher for further condensation, and the condensed water obtained from the reaction product can be refluxed to the boiling evaporator from the bottom of the heat exchanger and the quencher. The present invention integrates the reuse and preheating of raw water, and can meet the requirements of high efficiency and energy saving of industrial catalytic reactions.

[0057] The photocatalytic reaction device system and reaction method provided by the present invention have a simple structure and a high degree of automation. They can efficiently couple the photothermal conditions to drive the CO2 / N2 reduction reaction. By using the light-transmitting reaction coil as the reaction tube and combining the temperature control pipeline designed in the reactor shell, the working state of different temperature control pipelines can be modulated according to the temperature distribution of the reactor, so that the reactor is heated evenly, thereby effectively solving the problems of the reaction tube obstruction, incident light path change, catalyst deactivation, etc. caused by local water condensation. The reaction system provided by the present invention also makes full use of the raw water and the reaction product for heat exchange, while reducing the energy consumption of separating the product and heating the raw water. In addition, the recycling and reuse of condensed water can greatly reduce the water consumption of the process.

[0058] The reaction device and method provided by the present invention can meet the requirements of high rate and energy saving of industrial catalytic reaction, and the device has a simple structure, low equipment cost, simple method, strong controllability and high operability, and is more suitable for promotion and application of industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 A schematic structural diagram of the photocatalytic reaction system for reducing CO2 / N2 with water vapor provided by the present invention;

[0060] Figure 2 This is a simplified structural diagram of the reactor portion of the photocatalytic reaction system provided by the present invention. DETAILED DESCRIPTION

[0061] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0062] The raw materials involved in the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0063] The device materials involved in the present invention have no particular restrictions on their purity or standards. The present invention preferably adopts conventional purity or standards in the field of photocatalytic reactions.

[0064] All process and device names and their abbreviations in the present invention are conventional abbreviations in the field. Each name is clear and unambiguous in the field of its relevant use. Those skilled in the art can understand its conventional process steps and device structures based on the names.

[0065] The present invention provides a photocatalytic reaction system, which comprises:

[0066] Photocatalytic reactor;

[0067] a heat exchanger connected to the reactor;

[0068] a quench cooler connected to the heat exchanger;

[0069] a gas separation device connected to the quench cooler;

[0070] a boiling evaporator connected to the reactor and the heat exchanger respectively;

[0071] The photocatalytic reactor comprises a light-transmitting reaction coil and a photoreaction catalyst arranged on the inner wall of the light-transmitting reaction coil;

[0072] One end of the light-transmitting reaction coil is a reaction raw material inlet, and the other end is a reaction product outlet.

[0073] In the present invention, a transparent panel is preferably provided on the top of the light-transmitting reaction coil.

[0074] In the present invention, the material of the transparent panel preferably includes one or more of transparent glass, quartz glass, organic glass and ZnSe glass, and more preferably transparent glass, quartz glass, organic glass or ZnSe glass.

[0075] In the present invention, a temperature control pipeline is preferably provided around the light-transmitting reaction coil.

[0076] In the present invention, the temperature control pipeline is preferably a temperature control pipeline that can achieve overall and / or segmented temperature control of the light-transmitting reaction coil.

[0077] In the present invention, the photoreaction catalyst is preferably a photoreaction CO2 / N2 reduction catalyst.

[0078] In the present invention, the photoreaction catalyst preferably includes one or more of a metal nanocatalyst, a semiconductor nanocatalyst or a composite catalyst, and more preferably a metal nanocatalyst, a semiconductor nanocatalyst or a composite catalyst.

[0079] In the present invention, the heat exchanger preferably includes one or more of a shell and tube heat exchanger, a jacketed heat exchanger, a coiled tube heat exchanger and a shell and tube heat exchanger, and more preferably a shell and tube heat exchanger, a jacketed heat exchanger, a coiled tube heat exchanger or a shell and tube heat exchanger.

[0080] In the present invention, the heat medium inlet of the heat exchanger is preferably connected to the reaction product outlet.

[0081] In the present invention, the heat medium outlet of the heat exchanger is preferably connected to the heat medium inlet of the quench cooler.

[0082] In the present invention, the cold medium inlet of the heat exchanger is preferably connected to the water source.

[0083] In the present invention, the cold medium outlet of the heat exchanger is preferably connected to the inlet of the boiling evaporator through a first pipeline.

[0084] In the present invention, the heat exchanger is preferably provided with a condensate outlet.

[0085] In the present invention, the condensate outlet is preferably connected to the first pipeline.

[0086] In the present invention, the quench cooler preferably comprises a partitioning heat exchanger.

[0087] In the present invention, the gas separation device preferably includes one or more of a cryogenic liquefaction separation device, a pressure swing adsorption device and a membrane separation device, and more preferably a cryogenic liquefaction separation device, a pressure swing adsorption device or a membrane separation device.

[0088] In the present invention, the heat medium outlet of the quench cooler is preferably connected to the inlet of the gas separation device through a second pipeline.

[0089] In the present invention, the second pipeline is preferably provided with a temperature and / or pressure sensor, and more preferably provided with a temperature or pressure sensor.

[0090] In the present invention, the heating method of the boiling evaporator preferably includes one or more of external heating, partition wall type and electric heating tube type, and more preferably external heating, partition wall type or electric heating tube type.

[0091] In the present invention, the boiling evaporator preferably includes one or more of a liquid storage boiling evaporator, a spray boiling evaporator and a thin film boiling evaporator, and more preferably a liquid storage boiling evaporator, a spray boiling evaporator or a thin film boiling evaporator.

[0092] In the present invention, the reaction raw material inlet of the photocatalytic reactor is preferably connected to the feed pipeline.

[0093] In the present invention, the outlet of the boiling evaporator is preferably connected to the feed line through a third pipeline.

[0094] In the present invention, the photocatalytic reaction system preferably also includes one or more of a light source, a control system, an auxiliary control device and a sensor system, and more preferably a light source, a control system, an auxiliary control device or a sensor system.

[0095] In the present invention, the auxiliary control device preferably includes a flow control valve.

[0096] In the present invention, the sensing system preferably includes a temperature sensor and / or a pressure sensor, and more preferably a temperature sensor or a pressure sensor.

[0097] In the present invention, one or more of the feed pipeline, the first pipeline connecting the heat exchanger and the boiling evaporator, the third pipeline, the cold medium inlet of the quench cooler and the cold medium outlet of the quench cooler are preferably provided with a flow control valve.

[0098] In the present invention, the control system preferably realizes steady-state interlocking regulation by associating one or more of the auxiliary control device, the sensor system and the devices in the system.

[0099] The present invention provides a photocatalytic reaction method using the photocatalytic reaction system described in any one of the above technical solutions, comprising the following steps:

[0100] 1) The raw water is subjected to heat exchange and then boiled and evaporated to obtain water vapor;

[0101] 2) mixing the water vapor obtained in the above step with CO2 and / or N2 gas, and then feeding the mixture into a photocatalytic reactor, and performing a photocatalytic reaction under the action of incident light from a light source and a photocatalyst to obtain a reaction product;

[0102] 3) subjecting the reaction product obtained in the above steps to heat exchange and cooling, separation of water and / or part of the reaction product, and further gas separation to obtain a final product;

[0103] The heat exchange in step 3) is carried out with the raw water in step 1).

[0104] The present invention firstly subjects the raw water to heat exchange and then to boiling evaporation to obtain water vapor.

[0105] In the present invention, the boiling evaporation pressure is preferably 0.1 to 20 MPa, more preferably 4 to 16 MPa, and even more preferably 8 to 12 MPa.

[0106] In the present invention, the temperature after boiling evaporation is preferably 80 to 200°C, more preferably 100 to 180°C, and even more preferably 120 to 160°C.

[0107] In the present invention, the water vapor obtained in the above steps is mixed with CO2 and / or N2 gas and then sent into a photocatalytic reactor. Under the incident light of the light source and the action of the photocatalyst, a photocatalytic reaction is carried out to obtain a reaction product.

[0108] In the present invention, the pressure of the photocatalytic reaction is preferably 0.1 to 10 MPa, more preferably 2 to 8 MPa, and more preferably 4 to 6 MPa.

[0109] In the present invention, the pressure of the photocatalytic reaction is preferably not higher than the pressure of the boiling evaporation.

[0110] In the present invention, the light source preferably includes one or more of sunlight, xenon lamp, LED lamp, halogen tungsten lamp, mercury lamp and infrared lamp, more preferably sunlight, xenon lamp, LED lamp, halogen tungsten lamp, mercury lamp or infrared lamp.

[0111] In the present invention, the incident light intensity is preferably 5 to 4000 mW / cm 2 , more preferably 500 to 3500 mW / cm 2 , more preferably 1000 to 3000 mW / cm 2 , more preferably 1500 to 2500 mW / cm 2 .

[0112] In the present invention, the photocatalyst preferably includes a carrier-complexed photocatalyst.

[0113] In the present invention, the carrier preferably includes one or more of a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer and quartz glass, and more preferably a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer or quartz glass.

[0114] In the present invention, the reaction product in step 2) preferably includes one or more of CH4, CO and NH3, and O2, more preferably CH4, CO or NH3, and O2.

[0115] Finally, the present invention performs heat exchange and cooling on the reaction product obtained in the above steps, separates water and / or part of the reaction product, and then performs gas separation to obtain the final product;

[0116] The heat exchange in step 3) is carried out with the raw water in step 1).

[0117] In the present invention, after the gas separation, two final products are obtained, preferably one is O2 and the other is CH4 and / or CO, more preferably one is O2 and the other is CH4 or CO.

[0118] The present invention is to complete and refine the overall technical solution, better ensure the stability and controllability of the photocatalytic reaction, and further improve the light utilization rate and raw material utilization rate of the photocatalytic reaction. The above-mentioned water vapor reduction CO2 / N2 photocatalytic reaction system and photocatalytic reaction method may specifically include the following contents:

[0119] A photocatalytic reaction system for reducing CO2 / N2 using water vapor:

[0120] The modular device includes a reaction system, a sensing system, an auxiliary system and a control system;

[0121] The reaction system consists of a reactor, a heat exchanger, a quencher and a gas separation device which are connected in series.

[0122] Specifically, the reactor is a fixed bed reactor with a transparent upper surface, and the material of the transparent upper surface can be one of transparent glass, quartz glass, organic glass, and ZnSe glass; the tube is filled with a CO2 / N2 reduction catalyst, which can be one or more of a metal nanocatalyst, a semiconductor nanocatalyst, or a composite catalyst, and the raw gas undergoes a photocatalytic reaction in the tube; a raw gas inlet is provided on one side of the reactor, and a reaction product outlet is provided on the other side; and there are evenly distributed temperature control pipelines in the shell.

[0123] Specifically, the heat exchanger has a reaction product inlet on the lower left side, a cooling gas product outlet on the top, a condensed water outlet on the bottom, and can be connected to the flow control valve in front of the boiling evaporator; the heat exchanger can be one of a shell and tube heat exchanger, a jacketed heat exchanger, a coil heat exchanger, a shell and tube heat exchanger, etc.; one end of the heat exchanger shell is connected to the raw water feeding bin, and the other end is connected to the flow control valve in front of the boiling evaporator.

[0124] Specifically, the quencher has a reaction product feed port on the lower left side, a cooling gas product discharge port on the top, a condensed water discharge port on the bottom, and can be connected to the flow control valve in front of the boiling evaporator; the quencher can be a partition heat exchanger, which is one of a shell and tube heat exchanger, a jacket heat exchanger, a spray heat exchanger, an immersed coil heat exchanger, and a plate heat exchanger. There is a circulating cooling medium with a controllable flow rate in the shell side of the quencher.

[0125] Specifically, the gas separation device is a low-temperature liquefaction separation device, a pressure swing adsorption device or a membrane separation device; a pre-dryer can also be used to further dry the residual moisture, and the drying medium of the dryer is one or a mixture of molecular sieves, silica gel, soda lime, quicklime, and montmorillonite.

[0126] Specifically, the sensing system is composed of multiple temperature and pressure sensors. The temperature sensor can be one or more of a thermocouple, a thermistor, a resistance temperature detector (RTD) and an IC temperature sensor; the pressure sensor can be one or more of a strain gauge, a piezoresistive, a capacitive and a piezoelectric pressure sensor.

[0127] Specifically, the auxiliary system is composed of a plurality of flow control valves and a boiling evaporator.

[0128] Specifically, the flow control valve may be a throttle valve, a speed regulating valve, a diverter valve, a collecting valve or a diverter and collector valve.

[0129] Specifically, the heating method of the boiling evaporator can be one of external heating type, partition type, and electric heating tube type, and the evaporation method can be one of liquid storage type, spray type, and thin film boiling evaporator.

[0130] Specifically, the control system obtains the temperature and pressure sensor data of the system through the signal transmission line, modulates the working state of the auxiliary system, and realizes steady-state control of the reaction system.

[0131] The present invention also provides a method for a photocatalytic reaction system for reducing CO2 / N2 with water vapor as described in any one of the above technical solutions, comprising the following steps: raw water passing through a heat exchanger and condensed water obtained in a heat exchanger and a quencher (when reducing N2 with water vapor, the condensed water obtained in the heat exchanger and the quencher is collected as a product) pass through a flow control valve together and enter a boiling evaporator to be heated into water vapor, and then mixed with CO2 / N2 gas passing through a flow control valve and sent to a reactor, reacting to generate CH4 / CO / NH3 and O2 under the action of a CO2 / N2 reduction catalyst, and then the reaction products are sequentially fed into a heat exchanger and a quencher to separate unreacted water and NH3 products; the remaining reaction products are fed into the gas separation device to separate and obtain qualified CH4 / CO and O2 products; the control system performs steady-state regulation on the reaction system by acquiring real-time temperature and pressure sensor data.

[0132] Specifically, the operating pressure of the boiling evaporator is 0.1-20MPa, and the outlet temperature is 80-200°C; the pressure of the reactor is 0.1-10MPa, but not higher than the operating pressure of the boiling evaporator, and the outlet temperature is room temperature to 600°C; the operating pressure of the heat exchanger is 0.1-10MPa, but not higher than the operating pressure of the reactor, and the outlet temperature is -10-80°C; the operating pressure of the quench cooler is 0.1-10MPa, but not higher than the operating pressure of the heat exchanger, and the outlet temperature is -10-20°C.

[0133] Specifically, the CO2 / N2 reduction catalyst can be combined with a carrier to form a composite catalyst, specifically including one or more of a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer and quartz glass, more preferably a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer or a quartz glass.

[0134] Specifically, the light source of the incident light can be one or more of the sun, xenon lamp, LED lamp, halogen tungsten lamp, mercury lamp or infrared lamp, with a light intensity of 5 to 4000 mW / cm 2 .

[0135] Specifically, the control system can adjust the flow control valve of water raw material in real time by acquiring the pressure data of water vapor after the boiling evaporator; it can adjust the flow control valve of water vapor and CO2 / N2 raw materials in real time according to a preset ratio by acquiring the pressure data of water vapor and CO2 / N2 mixed gas before the planar reactor; it can adjust the heating power of the boiling evaporator in real time by acquiring the temperature data before the reactor; it can adjust the working state of the temperature control pipeline in the reactor shell in real time by acquiring the temperature data of the reactor; it can adjust the flow control valve of the corresponding refrigerant medium in real time by acquiring the temperature data after the quench cooler.

[0136] See also Figure 1 , Figure 1 The present invention provides a simplified structural diagram of a photocatalytic reaction system for reducing CO2 / N2 by water vapor, wherein the system comprises a reactor (1), a heat exchanger (2), a quencher (3), a gas separation device (4), a temperature / pressure sensor (5), a flow control valve (6), a boiling evaporator (7) and a control system (8).

[0137] See also Figure 2 , Figure 2 The present invention provides a simplified structural diagram of the reactor part of the photocatalytic reaction system, wherein the quartz glass (1.1), the reaction tube (1.2), the inner surface of the tube pre-uniformly coated with CuPd-loaded plasmon Au nanocatalyst (1.3) and the temperature control pipeline (1.4).

[0138] The above content of the present invention provides a photocatalytic reaction system and a photocatalytic reaction method for reducing CO2 / N2 by water vapor. The photocatalytic reaction system for reducing CO2 / N2 by water vapor specially designed by the present invention has a specific structure. The device system includes a reaction system, a sensing system, an auxiliary system and a control system. By using a light-transmitting reaction coil with a photoreaction catalyst arranged on the inner wall as the reaction area, and evenly distributing the temperature control pipeline in the shell layer of the reactor relative to the tube, the temperature distribution of the reactor is monitored in real time by the control system, and the working state of the temperature control pipeline is modulated, thereby achieving uniform temperature control of the reactor, and can avoid the problems of the reaction tube being blocked, the incident light path being changed, and the catalyst being deactivated due to the condensation of water in the reaction raw materials. Further, in the reaction system provided by the present invention, the reaction product is first allowed to enter the heat exchanger for heat exchange with the raw water, and then enter the quencher for further condensation, and the condensed water obtained from the reaction product can be refluxed to the boiling evaporator from the bottom of the heat exchanger and the quencher. The present invention integrates the reuse and preheating of raw water, and can meet the requirements of high efficiency and energy saving of industrial catalytic reactions.

[0139] The photocatalytic reaction device system and reaction method provided by the present invention have a simple structure and a high degree of automation. They can efficiently couple the photothermal conditions to drive the CO2 / N2 reduction reaction. By using the light-transmitting reaction coil as the reaction tube and combining the temperature control pipeline designed in the reactor shell, the working state of different temperature control pipelines can be modulated according to the temperature distribution of the reactor, so that the reactor is heated evenly, thereby effectively solving the problems of the reaction tube obstruction, incident light path change, catalyst deactivation, etc. caused by local water condensation. The reaction system provided by the present invention also makes full use of the raw water and the reaction product for heat exchange, while reducing the energy consumption of separating the product and heating the raw water. In addition, the recycling and reuse of condensed water can greatly reduce the water consumption of the process.

[0140] The reaction device and method provided by the present invention can meet the requirements of high rate and energy saving of industrial catalytic reaction, and the device has a simple structure, low equipment cost, simple method, strong controllability and high operability, and is more suitable for promotion and application of industrial production.

[0141] In order to further illustrate the present invention, a photocatalytic reaction system and a photocatalytic reaction method provided by the present invention are described in detail in combination with the embodiments below. However, it should be understood that these embodiments are implemented on the premise of the technical scheme of the present invention, and detailed implementation methods and specific operating processes are given only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments.

[0142] Example 1

[0143] Photocatalytic reaction device for reducing CO2 / N2 with water vapor to generate methane

[0144] like Figure 1 and Figure 2 As shown, a photocatalytic reaction device for reducing CO2 / N2 using water vapor comprises a reactor (1), a heat exchanger (2), a quencher (3), a gas separation device (4), a temperature / pressure sensor (5), a flow control valve (6), a boiling evaporator (7) and a control system (8).

[0145] The reactor (1) is composed of quartz glass (1.1) on the upper surface, a reaction tube (1.2), a plasmon Au nanocatalyst (1.3) pre-uniformly coated with CuPd-loaded plasmons on the inner surface of the tube, a temperature control pipeline (1.4) and a temperature sensor (5).

[0146] During the reaction, the raw water flowing through the heat exchanger enters the boiling evaporator after passing through the flow control valve and is heated into water vapor. Then, it is mixed with the CO2 gas passing through the flow control valve in a ratio of 1:2.2 and sent to the reactor. A xenon lamp is used as a simulated sunlight light source at 100-400mW / cm 2Under the light intensity of , CH4 and O2 are generated by reaction under the action of CuPd-loaded plasmonic Au nanocatalyst, and then the reaction products are successively input into the heat exchanger and the quencher to separate the unreacted water and return it to the raw water; the remaining reaction products are sent to the gas separation device to separate and obtain qualified CH4 and O2 products; the temperature control pipeline is regulated by the control system, and the reactor temperature is maintained at about 120°C.

[0147] Using the device and method in Example 1, the selectivity of reducing CO2 to CH4 with water vapor is 98%, and the rest is C 2+ Product, CH4 yield is 0.5~2mmolg cat -1 h -1 .

[0148] Compared with traditional photocatalytic reaction systems, this method has significantly higher reaction selectivity and yield, and energy consumption is greatly reduced.

[0149] Example 2

[0150] Photocatalytic reaction device for reducing CO2 / N2 with water vapor to generate ammonia

[0151] like Figure 1 and Figure 2 As shown, a photocatalytic reaction device for reducing CO2 / N2 using water vapor comprises a reactor (1), a heat exchanger (2), a quencher (3), a temperature / pressure sensor (5), a flow control valve (6), a boiling evaporator (7) and a control system (8).

[0152] The reactor (1) is composed of quartz glass (1.1) on the upper surface, a reaction tube (1.2), an inner surface of the tube pre-uniformly coated with Au@Ru nanocatalyst (1.3), a temperature control pipeline (1.4) and a temperature sensor (5).

[0153] During the reaction, the raw water flowing through the heat exchanger enters the boiling evaporator after passing through the flow control valve and is heated into water vapor. Then, it is mixed with the N2 gas passing through the flow control valve at a ratio of 1:2.5 and sent to the reactor. A xenon lamp is used as a simulated sunlight light source at 400-800mW / cm 2 Under the light intensity of Au@Ru nanocatalyst, NH3 and O2 are generated, and then the reaction products are successively input into the heat exchanger and the quencher, and the reaction product ammonia water is collected and separated; the temperature control pipeline is regulated by the control system, and the reactor temperature is maintained at about 200℃.

[0154] Using the device and method in Example 2, the selectivity of reducing N2 with water vapor to generate NH3 is 100%, and the NH3 yield is 0.1-0.3 mmolg cat-1 h -1 .

[0155] Compared with traditional photocatalytic reaction systems, this method has significantly higher reaction selectivity and yield, and energy consumption is greatly reduced.

[0156] The above is a detailed introduction to a photocatalytic reaction system and a photocatalytic reaction method for reducing CO2 / N2 by water vapor provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and its core ideas of the present invention, including the best mode, and also enables any technician in the field to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements that are not different from the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A photocatalytic reaction system, characterized in that: The photocatalytic reaction system comprises: Photocatalytic reactor; a heat exchanger connected to the reactor; a quench cooler connected to the heat exchanger; a gas separation device connected to the quench cooler; a boiling evaporator connected to the reactor and the heat exchanger respectively; The photocatalytic reactor comprises a light-transmitting reaction coil and a photoreaction catalyst arranged on the inner wall of the light-transmitting reaction coil; One end of the light-transmitting reaction coil is a reaction raw material inlet, and the other end is a reaction product outlet.

2. The photocatalytic reaction system according to claim 1, characterized in that: A transparent panel is arranged on the top of the light-transmitting reaction coil; The material of the transparent panel includes one or more of transparent glass, quartz glass, organic glass and ZnSe glass; A temperature control pipeline is arranged around the light-transmitting reaction coil; The temperature control pipeline is specifically a temperature control pipeline for realizing the overall and / or segmented temperature control of the light-transmitting reaction coil; The photoreaction catalyst is specifically a photoreaction CO2 / N2 reduction catalyst.

3. The photocatalytic reaction system according to claim 1, characterized in that: The photoreaction catalyst comprises one or more of a metal nanocatalyst, a semiconductor nanocatalyst or a composite catalyst; The heat exchanger includes one or more of a shell-and-tube heat exchanger, a jacketed heat exchanger, a coiled tube heat exchanger and a shell-and-tube heat exchanger; The heat medium inlet of the heat exchanger is connected to the reaction product outlet; The heat medium outlet of the heat exchanger is connected to the heat medium inlet of the quench cooler.

4. The photocatalytic reaction system according to claim 1, characterized in that: The cold medium inlet of the heat exchanger is connected to the water source; The cold medium outlet of the heat exchanger is connected to the inlet of the boiling evaporator through a first pipeline; The heat exchanger is provided with a condensate outlet; The condensate outlet is communicated with the first pipeline.

5. The photocatalytic reaction system according to claim 1, characterized in that: The quench cooler comprises a partitioning heat exchanger; The gas separation device includes one or more of a cryogenic liquefaction separation device, a pressure swing adsorption device and a membrane separation device; The hot medium outlet of the quench cooler is connected to the inlet of the gas separation device through a second pipeline; The second pipeline is provided with a temperature and / or pressure sensor.

6. The photocatalytic reaction system according to claim 1, characterized in that: The heating method of the boiling evaporator includes one or more of external heating, partition heating and electric heating tube heating; The boiling evaporator includes one or more of a liquid storage boiling evaporator, a spray boiling evaporator and a thin film boiling evaporator; The reaction raw material inlet of the photocatalytic reactor is connected to the feed pipeline; The outlet of the boiling evaporator is connected to the feed pipeline through a third pipeline.

7. The photocatalytic reaction system according to claim 6, characterized in that: The photocatalytic reaction system further includes one or more of a light source, a control system, an auxiliary control device and a sensor system; The auxiliary control device includes a flow control valve; The sensing system includes a temperature sensor and / or a pressure sensor; A flow control valve is provided at one or more of the feed pipeline, the first pipeline connecting the heat exchanger and the boiling evaporator, the third pipeline, the cold medium inlet of the quench cooler and the cold medium outlet of the quench cooler; The control system realizes steady-state interlocking regulation by associating one or more of the auxiliary control device, the sensor system and the devices in the system.

8. A photocatalytic reaction method using the photocatalytic reaction system according to any one of claims 1 to 7, characterized in that: The following steps are involved: 1) The raw water is subjected to heat exchange and then boiled and evaporated to obtain water vapor; 2) mixing the water vapor obtained in the above step with CO2 and / or N2 gas, and then feeding the mixture into a photocatalytic reactor, and performing a photocatalytic reaction under the action of incident light from a light source and a photocatalyst to obtain a reaction product; 3) subjecting the reaction product obtained in the above steps to heat exchange and cooling, separation of water and / or part of the reaction product, and further gas separation to obtain a final product; The heat exchange in step 3) is carried out with the raw water in step 1).

9. The photocatalytic reaction method according to claim 8, characterized in that: The boiling evaporation pressure is 0.1-20 MPa; The temperature after boiling and evaporation is 80-200°C; The pressure of the photocatalytic reaction is 0.1-10 MPa; The pressure of the photocatalytic reaction is not higher than the pressure of the boiling evaporation; The light source includes one or more of sunlight, a xenon lamp, an LED lamp, a tungsten halogen lamp, a mercury lamp and an infrared lamp.

10. The photocatalytic reaction method according to claim 8, characterized in that: The incident light intensity is 5-4000 mW / cm 2 ; The photocatalyst includes a carrier-composite photocatalyst; The carrier includes one or more of a carbon carrier, a silica carrier, an alumina carrier, a ceramic carrier, a molecular sieve, silicon carbide, kaolin, a fluoropolymer and quartz glass; The reaction products in step 2) include one or more of CH4, CO and NH3, and O2; After the gas is separated, two final products are obtained, one is O2 and the other is CH4 and / or CO.

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