Method and device for photocatalytic rotational flow enhanced hydrogen production of organic wastewater

Abstract

The invention relates to an organic wastewater photocatalytic rotational flow enhanced hydrogen production method and device, and provides an organic wastewater photocatalytic rotational flow enhanced hydrogen production method, which comprises the following steps: (A) shear oscillation mixing of a catalyst and wastewater, (B) wastewater rotational flow oscillation photocatalytic hydrogen production, and (C) gas-liquid-solid three-phase separation and catalyst reuse. The invention further provides an organic wastewater photocatalytic rotational flow enhanced hydrogen production device. Organic matter pollutants in water are decomposed under the action of the catalyst, chemical energy of the organic matter pollutants is recycled in the form of hydrogen, cooperation of wastewater photocatalytic hydrogen production and wastewater treatment is achieved, the reaction rate of wastewater photocatalytic hydrogen production is increased, and secondary pollution caused by the reaction catalyst is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater photocatalytic hydrogen production, and relates to a method and device for photocatalytic cyclone-enhanced hydrogen production from organic wastewater. Background Art

[0002] With the continuous development of society, the demand for energy consumption continues to increase. At present, my country's energy is still dominated by traditional fossil energy, which leads to increasingly severe environmental problems. Since my country proposed the "dual carbon target" in 2020, the green and low-carbon transformation of energy is imminent. Hydrogen energy is a clean energy with high energy density, zero pollution and wide application. The use of photolysis of organic wastewater to produce hydrogen is considered to be a comprehensive solution to energy consumption and environmental problems with great development prospects. High-concentration organic wastewater from chemical enterprises has the characteristics of poor biodegradability and high biological toxicity. High-concentration organic wastewater is generally treated by advanced oxidation technology such as Fenton oxidation to reduce biological toxicity and improve biodegradability before biochemical treatment. However, the cost of wastewater treatment by this technology is high, which is contrary to the original intention of resource utilization. While the wastewater photocatalytic hydrogen production technology produces hydroxyl radicals to oxidize and decompose organic matter, the photogenerated electrons of the catalyst combine with hydrogen ions in the solution to generate hydrogen, achieving the goal of synergistic wastewater treatment and resource recycling.

[0003] In order to improve the reaction efficiency and industrial promotion of photocatalytic hydrogen production from wastewater, improve the utilization rate of light energy, and solve problems such as low photocatalytic efficiency of the reactor, poor effluent quality, and difficulty in separating the catalyst from wastewater, researchers are currently conducting research mainly from the aspects of reactor design and optimization of separation methods.

[0004] In the process of reactor design, the arrangement of reaction light sources and the overall design of the reactor are the main directions for optimizing the design by many researchers. Reasonable combination of reactor design and arrangement of light sources can greatly improve the rate of photocatalytic reaction in the reaction system. Chinese invention patent application CN 117902673A discloses a packed bed photocatalytic reactor, which is characterized in that after the suspended matter is removed, a top-lit UV lamp is used to excite the solid catalyst attached to the broken glass to undergo a photocatalytic degradation reaction with the solution. Although the removal of suspended particles can effectively reduce the loss of light sources, its top-lit structure is not conducive to the effective distribution of light. The catalyst in the form of broken glass filler is placed in the reactor. Due to its low specific surface area and the large particle catalyst causing mutual shielding between the catalysts, the photocatalytic efficiency of the reactor is low.

[0005] Chinese invention patent application CN 117504773A discloses a photocatalytic hydrogen production device, which is characterized by designing a serpentine spherical expansion tube as a photocatalytic reactor, and placing a UV lamp inside the catalyst tube as a light source. Although the expansion tube can increase the residence time compared to a straight tube, the expansion tube has a very limited effect on the turbulent disturbance of the solution, and the expansion section will have a slow flow rate near the wall and easily produce a dead zone, causing the catalyst to deposit on the reactor wall, thereby affecting the subsequent photocatalytic reaction, and this type of jacket is not conducive to the cleaning and maintenance of the device, and lacks prospects for industrial application.

[0006] In addition, the rate of photocatalytic hydrogen production from wastewater is greatly affected by the catalyst. The smaller the catalyst particle size, the larger the specific surface area of ​​the catalyst, and the higher the corresponding reaction rate. However, the smaller the catalyst, the more difficult it is to separate the catalyst from the solution. In the process of wastewater treatment, the residue of the catalyst will cause secondary pollution to the water quality. The efficient and low-cost separation of the catalyst is also one of the main challenges faced by the industrial application of wastewater photocatalytic hydrogen production.

[0007] Therefore, in order to improve the efficiency of photocatalytic hydrogen production from wastewater and separate and recover catalysts in solution, the art urgently needs to develop a method and device that can overcome the above-mentioned technical defects. Summary of the invention

[0008] The present disclosure provides a new method and device for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, which can achieve efficient removal of organic matter in organic wastewater and recover its chemical energy in the form of hydrogen. This treatment method is cleaner and more efficient, requires simple equipment, has low investment cost, and does not generate secondary pollution, thus solving the problems existing in the prior art.

[0009] In one aspect, the present disclosure provides a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, the method comprising the following steps:

[0010] (A) Shear oscillation mixing of catalyst and wastewater: using a cyclonic flow field to perform preliminary shear mixing of catalyst particles and organic wastewater, and then oscillating and mixing the obtained preliminary mixture through a Venturi effect to obtain a mixed solution in which the catalyst is uniformly dispersed;

[0011] (B) Photocatalytic hydrogen production by wastewater cyclonic oscillation: the mixed solution obtained in step (A) is regulated to perform three-dimensional turbulent rotation to form a cyclonic field, and a light source is introduced into the center of the cyclonic field to produce hydrogen by photolysis, thereby obtaining a three-phase mixed solution of catalyst particles, wastewater and hydrogen; and

[0012] (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugal separation is performed using the density difference between catalyst particles, hydrogen and wastewater to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst particle solid phase is returned to the treatment process of step (A) for recycling.

[0013] In a preferred embodiment, in step (A), the COD content of the organic wastewater is 500-6000 mg / L; the particle size of the catalyst particles is 50-600 μm, and the catalyst includes COFs or TiO2.

[0014] On the other hand, the present disclosure provides a device for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, the device comprising:

[0015] A cyclone mixer, a cyclone photocatalytic reactor, a water pump and a cyclone gas-liquid-solid three-phase separator, wherein the cyclone mixer, the cyclone photocatalytic reactor and the cyclone gas-liquid-solid three-phase separator constitute a primary reaction unit; the mixed solution outlet of the cyclone mixer is connected to the double tangential cyclone inlet of the cyclone photocatalytic reactor, the three-phase mixed solution of wastewater, catalyst particles and hydrogen obtained by photolysis of hydrogen in the cyclone photocatalytic reactor is discharged from the bottom outlet of the cyclone photocatalytic reactor, is pressurized by the water pump and is discharged from the water pump outlet, and is connected to the water pump outlet. The catalyst particles solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator, and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, and refluxes to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet.

[0016] In a preferred embodiment, the device further comprises a carbon dioxide absorption tower, wherein the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator into the carbon dioxide absorption tower.

[0017] In another preferred embodiment, the number of reaction units increases according to the increase of COD content of organic wastewater, including 1-4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:1.

[0018] In another preferred embodiment, when the COD content is 500 mg / L-less than 1000 mg / L, single-stage treatment is adopted; when the COD content is 1000 mg / L-less than 3000 mg / L, two-stage series treatment is adopted; when the COD content is 3000 mg / L-less than 4500 mg / L, three-stage series treatment is adopted; when the COD content is 4500-6000 mg / L, four-stage series treatment is adopted.

[0019] In another preferred embodiment, the cyclone mixer comprises: a mixer liquid phase tangential inlet, a mixer column section, a catalyst distributor, a venturi mixing section, a mixed solution outlet and a mixer catalyst inlet; wherein the mixer liquid phase tangential inlet is located at the bottom of the mixer column section, and the catalyst distributor is coaxially arranged at the bottom of the mixer column section; the venturi mixing section is composed of two spherical shells with decreasing diameters, which are located above the mixer column section and connected to the mixed solution outlet;

[0020] The diameter D1 of the cyclone mixer is 1:2, the height H1 of the mixer column is 1:2, and the diameter D 12 It is 0.5D1, and the radius of the spherical shell of the Venturi mixing section R1:R2 is 2:1.

[0021] In another preferred embodiment, the cyclone photocatalytic reactor comprises: a reactor column section, a reactor cone section, a double tangential cyclone inlet, a central light source, an anti-vortex baffle and a bottom outlet; wherein the double tangential cyclone inlet is arranged in the middle of the reactor column section; the central light source comprises a quartz light-transmitting lamp column and a mercury lamp, which are arranged in the center of the cyclone photocatalytic reactor and connected to the top of the reactor; the bottom outlet is connected to the bottom of the reactor cone section; the center lines of the anti-vortex baffle, the central light source and the bottom outlet coincide;

[0022] The reactor column diameter D2: column height H2 is 1:1, the reactor cone angle α2 is 60° to 120°, and the tangential inlet diameter D 21 : Bottom outlet diameter D 22 is 1:2.

[0023] In another preferred embodiment, the cyclone gas-liquid-solid three-phase separator comprises: a tangential inlet, a gas-liquid separation section, a spiral guide vane and a solid-liquid separation section; wherein the gas-liquid separation section comprises a gas-liquid separation section column section, a central inner cone, a gas phase outlet and a liquid phase outlet connected to the top of the spiral guide vane; the spiral guide vane is located between the gas-liquid separation section and the solid-liquid separation section; the solid-liquid separation section comprises a solid-liquid separation section column section, a solid-liquid separation section cone section, an overflow outlet and a solid phase outlet located at the center of the spiral guide vane, wherein the overflow outlet runs through the gas-liquid separation section and extends out along the side of the liquid phase outlet of the gas-liquid separation section,

[0024] Among them, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section and the columnar length H 31 The ratio D3:H3:H 31 is 1:4:1, the diameter of the liquid phase outlet of the gas-liquid separation section is D 31 is 0.5D3, the overflow outlet diameter of the solid-liquid separation section is D 32 is 0.3D3, the cone angle of the center is α 31 The cone angle of the solid-liquid separation cone is 16°.32 It is 6°~15°.

[0025] In another aspect, the present disclosure provides a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the above-mentioned device, the method comprising the following steps:

[0026] (a) Mixing of catalyst and wastewater: The wastewater entering the cyclone mixer tangentially and the catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are preliminarily mixed under the action of the cyclone field; then the preliminarily mixed solution enters the Venturi mixing section of the cyclone mixer to achieve uniform mixing of the wastewater and the catalyst particles to obtain a fully mixed material;

[0027] (b) Cyclone-enhanced photocatalytic decomposition of wastewater to produce hydrogen: the fully mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and a central light source is used to excite the wastewater photocatalytic reaction to decompose the organic wastewater to obtain hydrogen;

[0028] (c) gas-liquid-solid three-phase separation: the hydrogen obtained in step (b) and the wastewater mixed with the catalyst are sent to a cyclonic gas-liquid-solid three-phase separator, and the gas-liquid separation is completed in the middle of the separator. The gas is discharged from the gas phase outlet, and the liquid and the catalyst enter the lower solid-liquid separation section. In the solid-liquid separation section, the catalyst particles and the liquid are separated from each other by the difference in density between the catalyst and the liquid under the action of the spiral guide vanes;

[0029] (d) Multi-stage treatment and reflux: the catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a), a portion of the treated liquid phase discharged from the separator is returned to step (a), and the other portion enters the next stage reaction unit to repeat steps (ad) until the treated water meets the water quality standards;

[0030] (e) Hydrogen purification and collection: The gas phase product separated in the gas-liquid-solid three-phase separator is introduced from the bottom of the carbon dioxide absorption tower, and the pure hydrogen product is obtained after absorption and purification in the carbon dioxide absorption tower.

[0031] Beneficial effects:

[0032] (1) By adopting a cyclonic photocatalytic reactor, the activation energy of the wastewater photocatalytic hydrogen production reaction is reduced by tensile and compressive stress strain, turbulent flow breaks up liquid microclusters, improves the mass transfer rate, promotes gas removal, and increases the active sites of the catalyst. The photocatalytic hydrogen production reaction of wastewater is strengthened from three aspects, which significantly improves the rate of the wastewater photocatalytic hydrogen production reaction.

[0033] (2) A complete wastewater photocatalytic hydrogen production process is formed by combining a cyclone mixer, a cyclone photocatalytic reactor and a cyclone gas-liquid-solid three-phase separator, thereby achieving enhanced control of the entire process from wastewater mixing, catalytic reaction and product separation, minimizing catalyst waste while ensuring a high reaction rate, and having the characteristics of low catalyst loss and small secondary pollution.

[0034] (3) A cyclone photocatalytic reactor, a cyclone gas-liquid-solid three-phase separator and a cyclone mixer are used as a treatment unit. Through the two methods of multiple units in series and reflux ratio adjustment, effective purification of wastewater with a wide range of organic pollutant concentrations is achieved, and it has a high resistance to shock loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide further understanding of the present disclosure. They only constitute a part of this specification to further explain the present disclosure, and do not constitute a limitation of the present disclosure.

[0036] Figure 1 It is a schematic diagram of the process of photocatalytic cyclone-enhanced hydrogen production from organic wastewater according to a preferred embodiment of the present disclosure.

[0037] Figure 2 It is a schematic diagram of the structure of a cyclone mixer according to a preferred embodiment of the present disclosure.

[0038] Figure 3 It is a schematic diagram of the structure of a cyclonic photocatalytic reactor according to a preferred embodiment of the present disclosure.

[0039] Figure 4 It is a schematic diagram of the structure of a cyclonic gas-liquid-solid three-phase separator according to a preferred embodiment of the present disclosure.

[0040] Figure 5 It is a schematic diagram of the process of photocatalytic cyclone-enhanced hydrogen production from tertiary organic wastewater according to Example 1 of the present application. DETAILED DESCRIPTION

[0041] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0042] In view of the problems existing in the prior art, such as low photocatalytic efficiency of the reactor, poor effluent quality, and difficulty in separating the catalyst from the wastewater, the present application adopts a cyclone mixer, a cyclone photocatalytic reactor and a cyclone gas-liquid-solid three-phase separator to form a complete wastewater photocatalytic hydrogen production process, which uses photocatalytic decomposition of organic matter in the wastewater while producing hydrogen, uses chemical energy in the wastewater to achieve resource recovery in the form of hydrogen, oxidizes organic pollutants in the water body into carbon dioxide and water, reduces the COD of the wastewater, and achieves the goal of coordinated water purification and resource recovery; after the photocatalytic reaction, a mixed solution containing hydrogen and catalyst particles is obtained, and the mixed solution enters the cyclone gas-liquid-solid three-phase separator to complete the separation of the solid-liquid-gas three phases; the cyclone gas-liquid-solid three-phase separator adopts a design of degassing first and then removing solids, which improves the solid separation efficiency; the effective separation of catalyst particles can minimize the waste of catalyst, while avoiding the escape of catalyst into the water body to cause secondary pollution, and can adjust the treatment liquid reflux ratio to change the residence time of the wastewater to ensure the effluent water quality when the organic matter concentration in the wastewater is too high, and has a wide range of water quality application.

[0043] The applicant found that the wastewater photocatalytic hydrogen production reaction is a quasi-first-order reaction, and the first-order reaction kinetic formula is as follows:

[0044]

[0045] In the formula, c A is the concentration of reactants, k is the rate constant, and t is the reaction time.

[0046] From this we can get the first-order reaction rate and reactant concentration c A The reaction rate is inversely proportional to the square, and the concentration of the reaction solution has a great influence on the reaction rate. Ensuring a uniform distribution of the concentration of the reaction solution is one of the main means to ensure the maximization of the reaction rate of the first-order reaction. The principle of uniform mixing is to use the generated turbulence to break the fluid into microclusters, and the size of the microclusters depends on the degree of turbulence. Intense turbulence can reduce the size of the microclusters, and the smaller the size of the microclusters, the faster the process of achieving uniformity on the molecular scale through molecular diffusion of the solution. In the cyclone, the cyclonic flow field has the characteristics of high turbulence, which can minimize the size of the microclusters, make the concentration of the reaction solution uniformly distributed, and increase the reaction rate.

[0047] In the process of photocatalytic hydrogen production from wastewater, the generated hydrogen will adhere to the active sites of the catalyst, reducing the effective contact area between the catalyst and the reaction solution. The mass transfer rate between the hydrogen generated on the catalyst surface and the solution is an important factor limiting its reaction rate. Removing the attached hydrogen will facilitate the photocatalytic reaction. In the cyclone, the high-speed flow of liquid around the center of the cyclone will produce a negative pressure zone in the center of the cyclone field, see Henry's law below

[0048] p * =Ex

[0049] where p * —equilibrium partial pressure of the solute in the gas phase, kPa;

[0050] x—the mole fraction of solute in the liquid phase;

[0051] E—Henry coefficient, kP a .

[0052] Henry's law shows that the negative pressure area will reduce the equilibrium partial pressure of hydrogen, causing the hydrogen in the solution to precipitate and coalesce in the form of small bubbles in the negative pressure area. This process will effectively reduce the hydrogen concentration c in the solution. Since hydrogen is a sparingly soluble gas, the hydrogen mass transfer rate is controlled by the liquid film. According to the absorption rate equation:

[0053] N A =K L (c * -c)

[0054] In the formula, K L —Total absorption coefficient of liquid phase, kmol / (m 2 ·s·kmol / m 3 );

[0055] N A —Liquid film absorption rate, kmol / (m 2 ·s)

[0056] c*—mass concentration of hydrogen at the phase interface, kmol / m 3 ,

[0057] c—Hydrogen concentration in solution, kmol / m 3 .

[0058] Lowering the hydrogen concentration c in the solution can speed up the liquid absorption rate of hydrogen produced on the catalyst surface, while preventing hydrogen from precipitating on the surface of catalyst particles, which would affect the reaction rate of photocatalytic hydrogen production from wastewater.

[0059] Tensile and compressive strain can effectively reduce the activation energy of chemical reactions by changing the atomic structure and electronic properties of materials, which makes them play an important role in improving the catalytic performance of catalysts. The principle of strain effect is mainly reflected in the following aspects:

[0060] First, lattice stress affects the electronic structure. When a material is stretched or compressed, the distance between atoms in the lattice changes. This change affects the electronic band structure of the material, thereby changing the adsorption behavior of reactants on the catalyst surface. Tensile strain usually increases the distance between atoms, adjusts the electronic structure, and makes the active sites on the surface more conducive to the binding and dissociation of reactants, thereby reducing the activation energy of the reaction.

[0061] Secondly, the relationship between strain and adsorption energy and reaction can be further studied through theoretical simulation. According to density functional theory (DFT) simulation, tensile or compressive strain directly affects the adsorption energy of reactants by changing the electronic state of the catalyst surface, thereby regulating the activation energy of chemical reactions. In the electrocatalytic processes of oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), applying strain can significantly improve the performance of catalysts. This method of regulating catalyst performance through strain is particularly suitable for alloy and core-shell catalysts, where strain can change the interaction between different metal elements and enhance the overall catalytic effect.

[0062] Again, the combined effect of geometric strain and energy factors in strain regulation is also crucial. Taking core-shell nanoparticles as an example, geometric strain and the electronic state of the core material have a direct impact on the activity of the catalyst. When strain is applied to a core-shell catalyst, the lattice constant of the shell metal changes, thereby changing its electronic band structure. This change includes both structural deformation caused by geometric strain and energy regulation of the core material on the electronic state of the shell. By rationally selecting the core material and adjusting the thickness of the shell, the strain effect can be optimized, thereby regulating the activation energy and catalytic performance of the reaction.

[0063] In summary, tensile and compressive strain can significantly improve the performance of the catalyst by changing the electronic structure and geometric morphology of the catalyst material and reducing the activation energy of the chemical reaction. Due to the presence of a three-dimensional high-speed swirling turbulent field in the swirl field, the catalyst particles in it will be continuously subjected to constantly changing tensile and compressive strain forces, thereby reducing the activation energy of the wastewater photocatalytic hydrogen production reaction.

[0064] In a first aspect of the present disclosure, a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater is provided, the method comprising the following steps:

[0065] (A) Shear oscillation mixing of catalyst and wastewater: using a cyclonic flow field to perform preliminary shear mixing of catalyst particles and organic wastewater, and then oscillating and mixing the preliminary mixture through a Venturi effect to obtain a mixed solution in which the catalyst is evenly dispersed;

[0066] (B) Photocatalytic hydrogen production by swirl oscillation of wastewater: the mixed solution is regulated to perform three-dimensional turbulent rotation to form a swirl field, and a light source is introduced into the center of the swirl field to produce hydrogen by photolysis; the liquid microclusters in the solution are broken up by the high turbulence of the fluid in the swirl field, thereby increasing the mass transfer rate of the reaction; at the same time, the swirl excites the micro-interface oscillation on the catalyst surface; the activation energy of the wastewater photocatalytic reaction is reduced, the reaction rate of photocatalytic hydrogen production is increased, and a three-phase mixed solution of catalyst particles, hydrogen and wastewater is obtained;

[0067] (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugal separation is performed using the density difference between catalyst particles, hydrogen and wastewater to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst is refluxed to the treatment process of step (A) for recycling.

[0068] In the present disclosure, the COD (chemical oxygen demand) content of the organic wastewater is 500-6000 mg / L.

[0069] In the present disclosure, the catalyst is in a granular form, the particle size of the catalyst particles is 50-600 μm, the catalyst includes COFs (covalent organic framework materials) or TiO2, and the Pt content thereof is 0.5-12% of the catalyst mass.

[0070] In the present disclosure, in step (A), since cyclone mixing relies on the kinetic energy of the fluid for mixing, the accuracy of process control is poor, and the turbulent characteristics of the flow make it difficult to accurately control the mixing effect; and in the case of a Venturi mixer without premixing, due to the inertia of the solid particles and the rapid change of the flow rate in the mixer, the energy distribution in the fluid will be uneven, and the solid particles cannot effectively respond to these energy changes, resulting in difficulty in achieving uniform dispersion and mixing; using a cyclone to premix the catalyst and wastewater, premixing the catalyst and wastewater mixed micro-clusters into millimeter-level micro-clusters, and then using a Venturi mixer for fine mixing, a uniformly distributed catalyst-wastewater system can be obtained.

[0071] In a second aspect of the present disclosure, a device for photocatalytic cyclone-enhanced hydrogen production from organic wastewater is provided, the device comprising:

[0072] A cyclone mixer, a cyclone photocatalytic reactor, a water pump, a cyclone gas-liquid-solid three-phase separator and a carbon dioxide absorption tower, wherein the cyclone mixer, the cyclone photocatalytic reactor and the cyclone gas-liquid-solid three-phase separator constitute a primary reaction unit; the mixed solution outlet of the cyclone mixer is connected to the double tangential cyclone inlet of the cyclone photocatalytic reactor; after the photocatalytic hydrogen production of the cyclone photocatalytic reactor is completed, the three-phase mixed solution of wastewater, catalyst and hydrogen is discharged from the bottom outlet of the cyclone photocatalytic reactor, is pressurized by the water pump and discharged from the water pump outlet, and is discharged from the cyclone connected to the water pump outlet. The tangential inlet of the gas-liquid-solid three-phase separator enters the cyclone gas-liquid-solid three-phase separator. After the gas-liquid-solid three-phase separation is realized in the cyclone gas-liquid-solid three-phase separator, the solid phase of the catalyst particles is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator, and returns to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, and refluxes to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower.

[0073] In the present disclosure, the number of reaction units increases according to the increase of COD content of the treated wastewater, usually 1-4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:1.

[0074] In the present disclosure, when the COD content is 500 mg / L-less than 1000 mg / L, single-stage treatment is adopted; when the COD content is 1000 mg / L-less than 3000 mg / L, two-stage series treatment is adopted; when the COD content is 3000 mg / L-less than 4500 mg / L, three-stage series treatment is adopted; when the COD content is 4500-6000 mg / L, four-stage series treatment is adopted.

[0075] In the present disclosure, the cyclone mixer includes: a mixer liquid phase tangential inlet, a mixer column section, a catalyst distributor, a venturi mixing section, a mixed solution outlet and a mixer catalyst inlet; wherein the mixer liquid phase tangential inlet is located at the bottom of the mixer column section, and the catalyst distributor is coaxially arranged at the bottom of the mixer column section; the venturi mixing section is composed of two spherical shells with decreasing diameters, which are located above the mixer column section and connected to the mixed solution outlet.

[0076] In the present disclosure, the diameter D1 of the cyclone mixer: the height H1 of the mixer column is 1:2, and the diameter D 12 It is 0.5D1, and the radius of the spherical shell of the Venturi mixing section R1:R2 is 2:1.

[0077] In the present disclosure, the diameter D1 of the cyclone mixer is 200-800 mm.

[0078] In the present disclosure, the radius R1 of the spherical shell of the Venturi mixing section is 1 / 3D1-1 / 2D1.

[0079] In the present disclosure, the swirl photocatalytic reactor includes: a reactor column section, a reactor cone section, a double tangential swirl inlet, a central light source, an anti-vortex baffle and a bottom outlet; wherein the double tangential swirl inlet is arranged in the middle position of the reactor column section; the central light source includes a quartz translucent lamp column and a mercury lamp, which are arranged in the center of the swirl photocatalytic reactor and connected to the top of the reactor; the bottom outlet is connected to the bottom of the reactor cone section; the center lines of the anti-vortex baffle, the central light source and the bottom outlet coincide.

[0080] In the present disclosure, the reactor column diameter D2: column height H2 is 1:1, the reactor cone angle α2 is 60° to 120°, and the tangential inlet diameter D 21 : Bottom outlet diameter D 22 is 1:2.

[0081] In the present disclosure, the reactor column section diameter D2 is 300-3000 mm.

[0082] In the present disclosure, the tangential inlet diameter D 21 It is 0.05D2.

[0083] In the present disclosure, the cyclone gas-liquid-solid three-phase separator includes: a tangential inlet, a gas-liquid separation section, a spiral guide vane and a solid-liquid separation section; wherein the gas-liquid separation section includes a gas-liquid separation section column section, a central inner cone, a gas phase outlet and a liquid phase outlet connected to the top of the spiral guide vane; the spiral guide vane is located between the gas-liquid separation section and the solid-liquid separation section; the solid-liquid separation section includes a solid-liquid separation section column section, a solid-liquid separation section cone section, an overflow outlet and a solid phase outlet located at the center of the spiral guide vane, wherein the overflow outlet runs through the gas-liquid separation section and extends out along the side of the liquid phase outlet of the gas-liquid separation section.

[0084] In the present disclosure, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section and the columnar length H 31 The ratio D3:H3:H 31 is 1:4:1, the diameter of the liquid phase outlet of the gas-liquid separation section is D 31 is 0.5D3, the overflow outlet diameter of the solid-liquid separation section is D 32 is 0.3D3, the cone angle of the center is α 31 The cone angle of the solid-liquid separation cone is 16°. 32 It is 6°~15°.

[0085] In the present disclosure, the diameter D3 of the cyclone gas-liquid-solid three-phase separator is 50-500 mm.

[0086] In a third aspect of the present disclosure, a method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the above-mentioned device is provided, the method comprising the following steps:

[0087] (a) Mixing of catalyst and wastewater: The wastewater entering the cyclone mixer tangentially and the catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are preliminarily mixed under the action of the cyclone field; then the preliminarily mixed solution enters the Venturi mixing section of the cyclone mixer, in which the flow rate of the mixed solution increases rapidly, and the turbulence in the fluid increases, so that the wastewater and catalyst particles are uniformly mixed to obtain a fully mixed material;

[0088] (b) Cyclone-enhanced photocatalytic decomposition of wastewater to produce hydrogen: the fully mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and the wastewater photocatalytic reaction is stimulated by a central light source to decompose the organic wastewater to obtain hydrogen; wherein the high turbulence of the flow field in the cyclone field is utilized to enhance the surface renewal rate of the wastewater and the catalyst particles, break up the liquid micro-clusters of the fluid, and increase the photocatalytic hydrogen production reaction rate; at the same time, the surface of the catalyst particles is subjected to the continuously changing tensile and compressive strains in the cyclone field, and the surface tensile and compressive strains reduce the activation energy required for the catalyst reaction, thereby increasing the wastewater photocatalytic hydrogen production reaction rate;

[0089] (c) gas-liquid-solid three-phase separation: the hydrogen obtained in step (b) and the wastewater mixed with the catalyst are sent to a cyclonic gas-liquid-solid three-phase separator, and the gas-liquid separation is completed in the middle of the separator, the gas is discharged from the gas phase outlet, and the liquid and the catalyst enter the lower solid-liquid separation section, wherein, in the solid-liquid separation section, under the action of the spiral guide vanes, the flow rate of the mixed material in the separator is increased to strengthen the cyclonic flow field, and the catalyst particles and the liquid are separated from each other by utilizing the density difference between the catalyst and the liquid;

[0090] (d) multi-stage treatment and reflux: the catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a), a portion of the treated liquid phase discharged from the separator is returned to step (a), and the other portion enters the next stage reaction unit to repeat steps (ad) until the treated water meets the water quality standards; and

[0091] (e) Hydrogen purification and collection: The gas phase product separated in the gas-liquid-solid three-phase separator is introduced from the bottom of the carbon dioxide absorption tower, and the pure hydrogen product is obtained after absorption and purification in the carbon dioxide absorption tower.

[0092] In the present disclosure, according to the different COD content and difficulty of decomposition of organic matter in the actual water body, the multi-stage organic wastewater photocatalytic cyclone enhanced hydrogen production devices can be connected in series, while maintaining a high treatment efficiency and taking into account the requirements of treated water quality; by connecting the multi-stage organic wastewater photocatalytic cyclone enhanced hydrogen production reaction units in series, the COD content in the treated wastewater can be reduced step by step, and a better water quality treatment effect can be obtained and the hydrogen production efficiency can be improved; the generated gas is concentrated and introduced into a carbon dioxide absorption tower to absorb carbon dioxide to obtain pure hydrogen.

[0093] Please refer to the accompanying drawings below.

[0094] Figure 1 FIG. 1 is a schematic diagram of a process for photocatalytic cyclone-enhanced hydrogen production from organic wastewater according to a preferred embodiment of the present disclosure. Figure 1As shown, a cyclone mixer 1, a cyclone photocatalytic reactor 2 and a cyclone gas-liquid-solid three-phase separator 4 form a primary reaction unit; organic wastewater enters the cyclone mixer from the tangential inlet of the mixer liquid phase of the cyclone mixer, and the catalyst and the wastewater are shear-oscillated to obtain a mixed solution with uniform catalyst dispersion. After the catalyst concentration reaches the target concentration, the catalyst injection is stopped, and the catalyst circulates in the reaction device; the mixed solution is discharged from the mixed solution outlet of the cyclone mixer, enters the cyclone photocatalytic reactor through the double tangential cyclone inlets of the cyclone photocatalytic reactor, and wastewater cyclone oscillation photocatalytic hydrogen production is carried out to obtain a three-phase mixed solution of catalyst particles, wastewater and hydrogen; the three-phase mixed solution is discharged from the bottom outlet of the cyclone photocatalytic reactor, is pressurized by a water pump 3 and discharged from the water pump outlet, and is discharged from the water pump outlet after being connected with the water pump outlet. The catalyst particles solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator, and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, a part of it flows back to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the other part is discharged as purified water; the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5 (wherein the lean absorption liquid is added), the purified hydrogen is discharged from the top of the carbon dioxide absorption tower, and the rich absorption liquid is discharged from the bottom of the carbon dioxide absorption tower.

[0095] Figure 2 Schematic diagram of the structure of a cyclone mixer according to a preferred embodiment of the present disclosure. Figure 2 As shown, the cyclone mixer comprises: a mixer liquid phase tangential inlet 11, a mixer column section 13, a catalyst distributor 12, a venturi mixing section 14, a mixed solution outlet 15 and a mixer catalyst inlet 16; wherein, the mixer liquid phase tangential inlet 11 is located at the bottom of the mixer column section 13, and the catalyst distributor 12 is coaxially arranged at the bottom of the mixer column section 13; the venturi mixing section 14 is composed of two spherical shells with decreasing diameters, which are located above the mixer column section 13 and connected to the mixed solution outlet 15; wherein, the diameter D1 of the cyclone mixer: the height H1 of the mixer column section is 1:2, and the diameter D1 of the catalyst distributor is 1:2. 12 is 0.5D1, and the radius of the spherical shell of the Venturi mixing section R1:R2 is 2:1;

[0096] The catalyst concentrate is ejected from the catalyst distributor and preliminarily mixed with the wastewater entering tangentially, and the preliminarily mixed solution enters the Venturi mixing section; since cyclonic mixing relies on the kinetic energy of the fluid for mixing, the accuracy of process control is poor, and the turbulent characteristics of the flow make it difficult to accurately control the mixing effect; and in the Venturi mixing section, without premixing, due to the inertia of the solid particles and the rapid change of flow rate in the mixer, the energy distribution in the fluid will be uneven, and the solid particles cannot effectively respond to these energy changes, resulting in difficulty in achieving uniform dispersion and mixing; after the catalyst and wastewater are premixed using a cyclonic mixer, they are finely mixed using the Venturi mixing section to obtain a uniformly distributed catalyst-wastewater system; during the mixing in the Venturi section, the continuous change in the flow rate of the mixed solution causes the Venturi effect, achieving uniform mixing of the wastewater and catalyst particles to obtain a fully mixed material system.

[0097] Figure 3 FIG. 1 is a schematic diagram of a cyclonic photocatalytic reactor structure according to a preferred embodiment of the present disclosure. Figure 3 As shown, the cyclone photocatalytic reactor comprises: a reactor column 21, a reactor cone 22, a double tangential cyclone inlet 23, a central light source 24, an anti-vortex baffle 25 and a bottom outlet 26; wherein the double tangential cyclone inlet 23 is arranged in the middle of the reactor column 21; the central light source 24 comprises a quartz light-transmitting lamp column 241 and a mercury lamp 242, which are arranged in the center of the cyclone photocatalytic reactor and connected to the top of the reactor; the bottom outlet 26 is connected to the bottom of the reactor cone 22; the center lines of the anti-vortex baffle 25, the central light source 24 and the bottom outlet 26 coincide; wherein the reactor column diameter D2: column height H2 is 1:1, the reactor cone angle α2 is 60° to 120°, the tangential inlet diameter D 21 : Bottom outlet diameter D 22 is 1:2;

[0098] The cyclonic photocatalytic reactor utilizes the high turbulence in the cyclonic field to enhance the renewal rate of the liquid film on the surface of the wastewater and the catalyst particles, and improves the photocatalytic hydrogen production reaction rate by increasing the mass transfer rate; at the same time, the catalyst particles are subjected to the continuously changing tensile and compressive strains in the cyclonic field, which will reduce the activation energy required for the catalyst reaction, thereby improving the photocatalytic hydrogen production reaction rate.

[0099] Figure 4 Schematic diagram of the structure of a cyclonic gas-liquid-solid three-phase separator according to a preferred embodiment of the present disclosure. Figure 4As shown, the cyclone gas-liquid-solid three-phase separator includes: a tangential inlet 41, a gas-liquid separation section 42, a spiral guide vane 43 and a solid-liquid separation section 44; wherein the gas-liquid separation section 42 includes a gas-liquid separation section column section 421, a central inner cone 422, a gas phase outlet 423 and a liquid phase outlet 445 connected to the top of the spiral guide vane 43; the spiral guide vane 43 is located between the gas-liquid separation section 42 and the solid-liquid separation section 44; the solid-liquid separation section 44 includes a solid-liquid separation section column section 441, a solid-liquid separation section cone section 442, an overflow outlet 444 and a solid phase outlet 443 located at the center of the spiral guide vane 43, wherein the overflow outlet 444 penetrates the gas-liquid separation section 42 and extends out along the side of the liquid phase outlet 445 of the gas-liquid separation section 42, wherein the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the gas-liquid separation section columnar height H3 and the solid-liquid separation section columnar length H 31 The ratio D3:H3:H 31 is 1:4:1, the diameter of the liquid phase outlet of the gas-liquid separation section is D 31 is 0.5D3, the overflow outlet diameter of the solid-liquid separation section is D 32 is 0.3D3, the cone angle of the center is α 31 The cone angle of the solid-liquid separation cone is 16°. 32 6°~15°;

[0100] The cyclone gas-liquid-solid three-phase separator adopts a design of degassing first and then removing solids, which can effectively reduce the entrainment of catalyst particles by gas during the liquid-solid separation process and improve the solid separation efficiency; the spiral guide vanes installed between the gas-liquid separation zone and the liquid-solid separation zone can increase the flow rate of the liquid flowing out of the gas-liquid separation zone, thereby increasing the difference between the inertial force and the centrifugal force exerted on the particles in the liquid in the flow field, intensifying the migration of the particles in the cone section to the wall, and improving the liquid-solid separation effect.

[0101] Figure 5 Schematic diagram of the process of photocatalytic cyclone-enhanced hydrogen production from tertiary organic wastewater according to Example 1 of the present application. Figure 5 As shown, three-stage reaction units are connected in series, and each stage of the reaction units is composed of a cyclone mixer 1, a cyclone photocatalytic reactor 2, and a cyclone gas-liquid-solid three-phase separator 4;

[0102] Primary reaction unit: organic wastewater with a COD of 3000 mg / L enters the cyclone mixer through the liquid phase tangential inlet of the cyclone mixer of the primary reaction unit, and the catalyst and the wastewater are shear-oscillated to obtain a mixed solution in which the catalyst is evenly dispersed; the mixed solution is discharged from the mixed solution outlet of the cyclone mixer, and enters the cyclone photocatalytic reactor through the double tangential cyclone inlets of the cyclone photocatalytic reactor, and wastewater cyclone oscillation photocatalytic hydrogen production is carried out to obtain a three-phase mixed solution of catalyst particles, wastewater and hydrogen; the three-phase mixed solution is discharged from the bottom outlet of the cyclone photocatalytic reactor, and is discharged from the outlet of the water pump after being pressurized by the water pump 3, and is tangentially inletted into the cyclone gas-liquid-solid three-phase separator connected to the water pump outlet. The catalyst particles solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator, and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; a part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, and refluxed to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the other part (COD has been reduced to 1100 mg / L) is sent to the cyclone mixer of the secondary reaction unit; the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5 (wherein the lean absorption liquid is added);

[0103] Secondary reaction unit: organic wastewater with a COD of 1100 mg / L enters the cyclone mixer from the liquid phase tangential inlet of the cyclone mixer of the secondary reaction unit, and the catalyst and the wastewater are shear-oscillated to obtain a mixed solution with uniformly dispersed catalyst; the mixed solution is discharged from the mixed solution outlet of the cyclone mixer, and enters the cyclone photocatalytic reactor through the double tangential cyclone inlets of the cyclone photocatalytic reactor, and wastewater cyclone oscillation photocatalytic hydrogen production is carried out to obtain a three-phase mixed solution of catalyst particles, wastewater and hydrogen; the three-phase mixed solution is discharged from the bottom outlet of the cyclone photocatalytic reactor, and is discharged from the outlet of the water pump after being pressurized by the water pump 3, and is discharged from the outlet of the water pump through the cyclone gas-liquid-solid three-phase reactor connected to the outlet of the water pump. The tangential inlet of the separator enters the cyclone gas-liquid-solid three-phase separator for gas-liquid-solid three-phase separation to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; a part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator and refluxed to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the other part (COD has been reduced to 500 mg / L) is sent to the cyclone mixer of the tertiary reaction unit; the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5;

[0104] Three-stage reaction unit: organic wastewater with a COD of 500 mg / L enters the cyclone mixer through the liquid phase tangential inlet of the cyclone mixer of the three-stage reaction unit, and the catalyst and the wastewater are shear-oscillated to obtain a mixed solution with uniformly dispersed catalyst; the mixed solution is discharged from the mixed solution outlet of the cyclone mixer, and enters the cyclone photocatalytic reactor through the double tangential cyclone inlets of the cyclone photocatalytic reactor, and wastewater cyclone oscillation photocatalytic hydrogen production is carried out to obtain a three-phase mixed solution of catalyst particles, wastewater and hydrogen; the three-phase mixed solution is discharged from the bottom outlet of the cyclone photocatalytic reactor, and is discharged from the outlet of the water pump after being pressurized by the water pump 3, and enters the cyclone gas-liquid-solid three-phase separator through the tangential inlet of the cyclone gas-liquid-solid three-phase separator connected to the water pump outlet. The three-phase separator performs gas-liquid-solid three-phase separation to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst particle solid phase is discharged from the solid phase outlet of the cyclone gas-liquid-solid three-phase separator, and returned to the cyclone mixer through the catalyst inlet of the mixer connected to the solid phase outlet; a part of the treated liquid phase is discharged from the liquid phase outlet of the cyclone gas-liquid-solid three-phase separator, refluxed to the cyclone mixer through the liquid phase tangential inlet of the mixer connected to the liquid phase outlet, and the other part (COD has been reduced to 50 mg / L) is discharged as purified water; the hydrogen-containing gas phase is discharged from the gas phase outlet of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower 5; the purified hydrogen is discharged from the top of the carbon dioxide absorption tower, and the rich absorption liquid is discharged from the bottom of the carbon dioxide absorption tower.

[0105] Example

[0106] The present invention will be further described below in conjunction with specific examples. However, it should be understood that these examples are only used to illustrate the present invention and do not constitute a limitation of the scope of the present invention. The test methods in the following examples that do not specify specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, all percentages and parts are by weight.

[0107] Embodiment 1:

[0108] According to the method of the present invention, organic wastewater treatment in the methanol to olefins (MTO) process is carried out, and its specific operation process and effect are described as follows:

[0109] 1.Material properties and related parameters

[0110] The main pollutants in the wastewater are phenol, cresol and hydroquinone, the processing capacity of the device is 3t / h, the COD content in the wastewater is 2500-3000mg / L, the catalyst used is COFs, the catalyst concentration in the reaction device is maintained at 0.05g / L, the catalyst particle size is 50-100μm, and the reaction temperature is room temperature.

[0111] 2. Process

[0112] like Figure 5 shown.

[0113] The three-stage organic wastewater photocatalytic cyclone enhanced hydrogen production device is connected in series, and the reflux ratio of the first-stage treated wastewater is 2:1, the reflux ratio of the second-stage treated wastewater is 2:1, and the reflux ratio of the third-stage treated wastewater is 4:1. The diameter of the first-stage cyclone photocatalytic reactor is 1500mm, the diameter of the second-stage cyclone photocatalytic reactor is 1500mm, and the diameter of the third-stage cyclone photocatalytic reactor is 3000mm. The catalyst concentration in the treated wastewater is controlled at 500mg / L.

[0114] 3. Main structural dimensions of the organic wastewater photocatalytic cyclone enhanced hydrogen production device

[0115]

[0116]

[0117] 4. Results Analysis

[0118] After 100 hours of continuous operation, the average effluent COD of the first-level organic wastewater photocatalytic cyclone enhanced hydrogen production device reached 1100mg / L, the average effluent COD of the second-level organic wastewater photocatalytic cyclone enhanced hydrogen production device reached 500mg / L, and the average effluent COD of the third-level organic wastewater photocatalytic cyclone enhanced hydrogen production device was 50mg / L. The average residence time of organic wastewater was 5h. The time it took for the reaction device to treat organic wastewater to meet the discharge standards was much shorter than that of general photocatalytic wastewater hydrogen production devices. After the catalyst is mixed with the wastewater once in the reaction device, the catalyst is recycled in the reaction device. When the purified water is discharged, the amount of catalyst carried out is less than 10ppm, and the concentration of suspended solids (ss) in the water is less than 15ppm, which is lower than the first-level standard of 20ppm in the "Comprehensive Sewage Discharge Standard", and the amount of hydrogen produced is 15.6m 3 / h.

[0119] Embodiment 2:

[0120] According to the method of the present invention, a 100L / h laboratory simulated organic wastewater process is carried out, and its specific operation process and effect are described as follows:

[0121] 1.Material properties and related parameters

[0122] The main pollutants in the wastewater are phenol, acetic acid, butanol, etc. The device processing capacity is 100L / h, the COD content in the wastewater is 800mg / L, the catalyst used is COFs, the catalyst concentration in the reaction device is maintained at 0.1g / L, the catalyst particle size is 50-60μm, and the reaction temperature is room temperature.

[0123] 2. Process

[0124] like Figure 1 shown.

[0125] A single-stage organic wastewater photocatalytic cyclone-enhanced hydrogen production device was used. The catalyst injection was stopped when the catalyst concentration in the reactor reached 1000 mg / L, and the reflux ratio was 3:1.

[0126] 3. Main structural dimensions of the organic wastewater photocatalytic cyclone enhanced hydrogen production device

[0127]

[0128]

[0129] 4. Results Analysis

[0130] After running continuously for 10 hours and the device is stable, the average effluent COD of the device is 30mg / L, and the average residence time of organic wastewater is 1h. The time it takes for the reaction device to treat organic wastewater to meet the discharge standard is much lower than that of general photocatalytic wastewater hydrogen production devices. After the catalyst is mixed with wastewater once, the catalyst is recycled in the reaction device. When the purified water is discharged, the amount of catalyst carried out is less than 8ppm, and the concentration of suspended solids (ss) in the water is less than 10ppm, which is lower than the first-level standard of 20ppm in the "Comprehensive Sewage Discharge Standard". It has little impact on the environment, and the amount of hydrogen produced is 1m 3 / h.

[0131] The above-listed embodiments are only preferred embodiments of the present disclosure and are not intended to limit the scope of implementation of the present disclosure. That is, all equivalent changes and modifications made according to the content of the patent scope of this application should be within the technical scope of the present disclosure.

[0132] All documents mentioned in this disclosure are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of this disclosure, those skilled in the art may make various changes or modifications to this disclosure, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, the method comprising the following steps: (A) Shear oscillation mixing of catalyst and wastewater: using a cyclonic flow field to perform preliminary shear mixing of catalyst particles and organic wastewater, and then oscillating and mixing the obtained preliminary mixture through a Venturi effect to obtain a mixed solution in which the catalyst is uniformly dispersed; (B) Photocatalytic hydrogen production by wastewater cyclonic oscillation: the mixed solution obtained in step (A) is regulated to perform three-dimensional turbulent rotation to form a cyclonic field, and a light source is introduced into the center of the cyclonic field to produce hydrogen by photolysis, thereby obtaining a three-phase mixed solution of catalyst particles, wastewater and hydrogen; and (C) Gas-liquid-solid three-phase separation and catalyst recycling: Centrifugal separation is performed using the density difference between catalyst particles, hydrogen and wastewater to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst particle solid phase is returned to the treatment process of step (A) for recycling.

2. The method according to claim 1, characterized in that: In step (A), the COD content of the organic wastewater is 500-6000 mg / L; the particle size of the catalyst particles is 50-600 μm, and the catalyst includes COFs or TiO2.

3. A device for photocatalytic cyclone-enhanced hydrogen production from organic wastewater, the device comprising: A cyclone mixer (1), a cyclone photocatalytic reactor (2), a water pump (3) and a cyclone gas-liquid-solid three-phase separator (4), wherein the cyclone mixer (1), the cyclone photocatalytic reactor (2) and the cyclone gas-liquid-solid three-phase separator (4) form a primary reaction unit; a mixed solution outlet (15) of the cyclone mixer is connected to a double tangential cyclone inlet (23) of the cyclone photocatalytic reactor; a three-phase mixed solution of wastewater, catalyst particles and hydrogen obtained by photolysis of hydrogen in the cyclone photocatalytic reactor is discharged from an outlet (26) at the bottom of the cyclone photocatalytic reactor, is pressurized by a water pump (3) and is discharged from an outlet of the water pump (3), and is connected to the water pump (3) to form a mixed solution outlet (15) of the cyclone mixer; and a mixed solution outlet (15) of the cyclone photocatalytic reactor is connected to a double tangential cyclone inlet (23) of the cyclone photocatalytic reactor. (3) The tangential inlet (41) of the cyclone gas-liquid-solid three-phase separator connected to the outlet enters the cyclone gas-liquid-solid three-phase separator for gas-liquid-solid three-phase separation to obtain a catalyst particle solid phase, a hydrogen-containing gas phase and a treated liquid phase, wherein the catalyst particle solid phase is discharged from the solid phase outlet (443) of the cyclone gas-liquid-solid three-phase separator and returned to the cyclone mixer through the catalyst inlet (16) of the mixer connected to the solid phase outlet (443); the treated liquid phase is discharged from the liquid phase outlet (445) of the cyclone gas-liquid-solid three-phase separator and refluxed to the cyclone mixer through the liquid phase tangential inlet (11) of the mixer connected to the liquid phase outlet (445).

4. The device according to claim 3, characterized in that The device also includes a carbon dioxide absorption tower (5), wherein the hydrogen-containing gas phase is discharged from the gas phase outlet (423) of the cyclone gas-liquid-solid three-phase separator and enters the carbon dioxide absorption tower (5).

5. The device according to claim 3, characterized in that The number of reaction units increases according to the increase of COD content of organic wastewater, including 1-4 stages; the reflux ratio of the treated liquid phase is 2:1 to 4:

1.

6. The device according to claim 5, characterized in that When the COD content is 500mg / L-less than 1000mg / L, single-stage treatment is adopted; when the COD content is 1000mg / L-less than 3000mg / L, two-stage series treatment is adopted; when the COD content is 3000mg / L-less than 4500mg / L, three-stage series treatment is adopted; when the COD content is 4500-6000mg / L, four-stage series treatment is adopted.

7. The device according to claim 3, characterized in that The cyclone mixer comprises: a mixer liquid phase tangential inlet (11), a mixer column section (13), a catalyst distributor (12), a venturi mixing section (14), a mixed solution outlet (15) and a mixer catalyst inlet (16); wherein the mixer liquid phase tangential inlet (11) is located at the bottom of the mixer column section (13), and the catalyst distributor (12) is coaxially arranged at the bottom of the mixer column section (13); the venturi mixing section (14) is composed of two spherical shells with decreasing diameters, is located above the mixer column section (13), and is connected to the mixed solution outlet (15); The diameter D1 of the cyclone mixer is 1:2, the height H1 of the mixer column is 1:2, and the diameter D 12 It is 0.5D1, and the radius of the spherical shell of the Venturi mixing section R1:R2 is 2:

1.

8. The device according to claim 3, characterized in that The cyclone photocatalytic reactor comprises: a reactor column section (21), a reactor cone section (22), a double tangential cyclone inlet (23), a central light source (24), an anti-vortex baffle (25) and a bottom outlet (26); wherein the double tangential cyclone inlet (23) is arranged in the middle of the reactor column section (21); the central light source (24) comprises a quartz light-transmitting lamp column (241) and a mercury lamp (242), which are arranged at the center of the cyclone photocatalytic reactor and connected to the top of the reactor; the bottom outlet (26) is connected to the bottom of the reactor cone section (22); the center lines of the anti-vortex baffle (25), the central light source (24) and the bottom outlet (26) coincide with each other; The reactor column diameter D2: column height H2 is 1:1, the reactor cone angle α2 is 60° to 120°, and the tangential inlet diameter D 21 : Bottom outlet diameter D 22 is 1:

2.

9. The device according to claim 3, characterized in that The cyclone gas-liquid-solid three-phase separator comprises: a tangential inlet (41), a gas-liquid separation section (42), a spiral guide vane (43) and a solid-liquid separation section (44); wherein the gas-liquid separation section (42) comprises a gas-liquid separation section column section (421), a central inner cone (422), a gas phase outlet (423) and a liquid phase outlet (445) connected to the top of the spiral guide vane (43); the spiral guide vane (43) is located between the gas-liquid separation section (42) and the solid-liquid separation section (44); the solid-liquid separation section (44) comprises a solid-liquid separation section column section (441), a solid-liquid separation section cone section (442), an overflow outlet (444) located at the center of the spiral guide vane (43) and a solid phase outlet (443); wherein the overflow outlet (444) penetrates the gas-liquid separation section (42) and extends out along the side of the liquid phase outlet (445) of the gas-liquid separation section (42). Among them, the diameter D3 of the cyclone gas-liquid-solid three-phase separator, the columnar height H3 of the gas-liquid separation section and the columnar length H 31 The ratio D3:H3:H 31 is 1:4:1, the diameter of the liquid phase outlet of the gas-liquid separation section is D 31 is 0.5D3, the overflow outlet diameter of the solid-liquid separation section is D 32 is 0.3D3, the cone angle of the center is α 31 The cone angle of the solid-liquid separation cone is 16°. 32 It is 6°~15°.

10. A method for photocatalytic cyclone-enhanced hydrogen production from organic wastewater using the device according to any one of claims 3 to 9, the method comprising the following steps: (a) Mixing of catalyst and wastewater: The wastewater entering the cyclone mixer tangentially and the catalyst concentrate flowing out of the catalyst distributor of the cyclone mixer are preliminarily mixed under the action of the cyclone field; then the preliminarily mixed solution enters the Venturi mixing section of the cyclone mixer to achieve uniform mixing of the wastewater and the catalyst particles to obtain a fully mixed material; (b) Cyclone-enhanced photocatalytic decomposition of wastewater to produce hydrogen: the fully mixed material obtained in step (a) is fed into a cyclone photocatalytic reactor, and a central light source is used to excite the wastewater photocatalytic reaction to decompose the organic wastewater to obtain hydrogen; (c) gas-liquid-solid three-phase separation: the hydrogen obtained in step (b) and the wastewater mixed with the catalyst are sent to a cyclonic gas-liquid-solid three-phase separator, and the gas-liquid separation is completed in the middle of the separator. The gas is discharged from the gas phase outlet, and the liquid and the catalyst enter the lower solid-liquid separation section. In the solid-liquid separation section, the catalyst particles and the liquid are separated from each other by the difference in density between the catalyst and the liquid under the action of the spiral guide vanes; (d) multi-stage treatment and reflux: the catalyst separated by the gas-liquid-solid three-phase separator is returned to step (a), a portion of the treated liquid phase discharged from the separator is returned to step (a), and the other portion enters the next stage reaction unit to repeat steps (ad) until the treated water meets the water quality standards; and (e) Hydrogen purification and collection: The gas phase product separated in the gas-liquid-solid three-phase separator is introduced from the bottom of the carbon dioxide absorption tower, and the pure hydrogen product is obtained after absorption and purification in the carbon dioxide absorption tower.

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