A photocatalytic kitchen waste hydrogen production system and its operation method

Abstract

The present invention belongs to the technical field of waste energy treatment, and provides a photocatalytic kitchen waste hydrogen production system and its operation method. The hydrogen production system includes a garbage crushing device, a leachate collection device, a hydrolysis reactor, a photocatalytic oxidation unit, a photocatalytic hydrogen production unit, a hydrothermal reactor, a solid-liquid separation device, an anaerobic digestion unit, a methane combined reforming unit, a CO collection device and an H2 collection device. The CH4 produced by anaerobic digestion is dry-reformed by the CO2 produced by photocatalytic oxidation, photocatalytic hydrogen production and anaerobic digestion, which makes up for the shortcoming of the low proportion of CO2 produced by anaerobic digestion. At the same time, water vapor produced by photocatalytic oxidation is added to the reforming unit to suppress the occurrence of carbon deposition, thereby improving the conversion rate of methane and the H2 / CO ratio in the reformed synthetic gas. The entire system has a reasonable structural design. On the basis of greatly improving the hydrogen production efficiency, it rationally utilizes the garbage leachate, and finally realizes the efficient hydrogen production from kitchen waste.

Description

Technical Field

[0001] The present invention relates to the technical field of waste energy treatment, and in particular to a photocatalytic kitchen waste hydrogen production system and an operation method thereof. Background Art

[0002] The only product of hydrogen combustion is water, and no greenhouse gases are produced, making it an ideal clean energy source. In the past, hydrogen was produced from fossil fuels or high-energy electrolysis. Producing hydrogen from food waste has the advantage of low energy consumption. Hydrogen production from food waste can be divided into chemical and biological methods. Chemical hydrogen production includes pyrolysis, gasification, and new supercritical water gasification. The disadvantages of chemical hydrogen production include easy deactivation of catalysts, easy corrosion of equipment, and hydrogen embrittlement. Biological hydrogen production is divided into anaerobic digestion hydrogen production and photosynthetic bacteria hydrogen production. However, the hydrogen production efficiency of these two methods is not high and is subject to various conditions.

[0003] Invention patent CN103832971A discloses a method for producing low-CO concentration hydrogen by photocatalytic reforming of methanol and biomass derivatives. It mainly uses TiO2 as a catalyst and uses methanol and biomass derivatives to produce low-concentration hydrogen. According to the reaction principle disclosed in the patent, a large amount of greenhouse gas CO2 will be produced in this process, but the patent does not properly treat it. Patent CN216426759U is a hydrogen production system for anaerobic fermentation of biogas from kitchen waste. According to the disclosed content, it mainly realizes hydrogen production from kitchen waste through anaerobic digestion and combined methane reforming (CSDRM) technology. Since the main components of biogas contain 50-80% methane and 20-40% carbon dioxide, the conversion rate of methane during the biogas dry reforming reaction is low. Unconverted methane easily causes carbon accumulation on the catalyst surface, reducing the reaction efficiency and resulting in a decrease in the yield of H2.

[0004] Therefore, it is of great significance to provide an efficient and environmentally friendly hydrogen production system. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems existing in the prior art and provide a photocatalytic kitchen waste hydrogen production system and an operation method thereof.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a photocatalytic kitchen waste hydrogen production system, which includes the following devices: a garbage crushing device, a leachate collection device, a hydrolysis reactor, a photocatalytic oxidation unit, a photocatalytic hydrogen production unit, a hydrothermal reactor, a solid-liquid separation device, an anaerobic digestion unit, a methane combined reforming unit, a CO collection device and an H2 collection device.

[0008] The present invention also provides an operating method of the kitchen waste hydrogen production system, comprising the following steps:

[0009] (1) Grinding the kitchen waste in a garbage crushing device to obtain a solid phase and leachate;

[0010] (2) hydrothermally carbonizing a portion of the solid phase in a hydrothermal reactor to obtain hydrothermal charcoal and a liquid phase;

[0011] (3) mixing the hydrothermal charcoal and the remaining solid phase in a hydrolysis reactor for hydrolysis to obtain small molecular organic matter;

[0012] (4) mixing small molecule organic matter and a tantalum-cerium oxide catalyst in a photocatalytic oxidation unit under an oxygen atmosphere to react and produce compounds, water vapor, and carbon dioxide;

[0013] (5) mixing the compound and a titanium dioxide catalyst in a photocatalytic hydrogen production unit under a nitrogen atmosphere to react and produce hydrogen, carbon dioxide, and other organic matter;

[0014] (6) digesting the leachate from step (1), the liquid phase from step (2), and other organic matter from step (5) in an anaerobic digestion unit to produce carbon dioxide and methane;

[0015] (7) The water vapor and carbon dioxide in step (4), the carbon dioxide in step (5), and the carbon dioxide and methane in step (6) are mixed in a methane combined reforming unit for reaction to obtain carbon monoxide and hydrogen.

[0016] Preferably, the mass ratio of the partial solid phase in step (2) to the remaining solid phase in step (3) is 1:3.5-4.5.

[0017] Preferably, the temperature of the hydrothermal carbonization in step (2) is 200-220° C., and the time is 11-13 h;

[0018] The hydrolysis temperature in step (3) is 30-40° C., the rotation speed is 0.3-0.9 r / min, and the time is 44-52 h.

[0019] Preferably, the preparation method of the tantalum-ceria catalyst in step (4) comprises the following steps:

[0020] Cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol are mixed, reacted and calcined in sequence to obtain the tantalum-ceria catalyst.

[0021] Preferably, the concentration of the ammonia solution is 7 to 8 mmol / L;

[0022] The mass volume ratio of the cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol is 4-5 g: 35-36 mg: 90-110 mL: 290-310 mL: 70-90 mL.

[0023] Preferably, the reaction temperature is 140-160°C and the reaction time is 44-52h;

[0024] The heating rate of the calcination is 8-12° C. / min, the target temperature is 380-420° C., and the holding time after reaching the target temperature is 1.5-2.5 hours.

[0025] Preferably, in step (4), the mass ratio of the small molecule organic matter to the tantalum-cerium oxide catalyst is 4.5-5.5:3.5-4.5, and the reaction temperature is 95-105° C.;

[0026] The mass ratio of the compound and the titanium dioxide catalyst in step (5) is 45-55:1, and the reaction temperature is 20-30°C.

[0027] Preferably, in the anaerobic digestion unit, the mass ratio of the leachate in step (1) and the liquid phase in step (2) to the mass ratio of the other organic matter in step (5) is 4.5-5.5:1.5-2.5; the digestion temperature in step (6) is 36-38° C. and the digestion time is 23-25 ​​days.

[0028] Preferably, the mass ratio of methane, carbon dioxide and water vapor in the methane combined reforming unit is 3.5-4.5:3.5-4.5:0.5-1.5; and the reaction temperature in step (7) is 800-1100°C.

[0029] The beneficial effects of the present invention are:

[0030] (1) The present invention provides a photocatalytic hydrogen production system from kitchen waste, comprising the following devices: a garbage crushing device, a leachate collection device, a hydrolysis reactor, a photocatalytic oxidation unit, a photocatalytic hydrogen production unit, a hydrothermal reactor, a solid-liquid separation device, an anaerobic digestion unit, a methane combined reforming unit, a CO collection device, and an H2 collection device. The entire system has a rational structural design, significantly improves the efficiency of photocatalytic hydrogen production from kitchen waste, rationally utilizes leachate, and ultimately achieves efficient hydrogen production from kitchen waste.

[0031] (2) The present invention hydrothermally carbonizes part of the solid phase obtained from the garbage crushing device, so that part of the kitchen waste is converted into hydrothermal charcoal before hydrolysis. As an effective additive, the hydrothermal charcoal can not only promote the decomposition of waste cooking oil in the hydrolysis reactor, but also accelerate the hydrolysis rate and improve the energy conversion rate.

[0032] (3) The present invention adopts photocatalytic oxidation technology to catalyze the small molecular organic matter after hydrolysis of kitchen waste under the catalysis of Ta-CeO2 catalyst to maximize the production of C1 compound formaldehyde and formic acid, and then generates hydrogen through photocatalysis, thereby greatly improving the efficiency of hydrogen production using kitchen waste as raw material.

[0033] (4) The present invention uses landfill leachate to improve the C / N ratio in the anaerobic digestion process and improve the buffering performance of the digestion system; the CO2 generated by the photocatalytic unit, the CO2 generated by the photocatalytic hydrogen production unit and the CO2 generated by the anaerobic digestion unit are used to dry reform the CH4 generated by the anaerobic digestion, thereby compensating for the disadvantage that the proportion of CO2 generated by the anaerobic digestion is low and the effective conversion of CH4 cannot be achieved. At the same time, water vapor generated by the photocatalytic oxidation unit is added to the combined methane reforming (CSDRM) unit to reduce and inhibit the occurrence of carbon deposition, thereby improving the conversion rate of methane and the H2 / CO ratio in the reformed synthetic gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the photocatalytic kitchen waste hydrogen production system of the present invention (wherein 1 is a garbage crushing device, 2 is a leachate collecting device, 3 is a hydrolysis reactor, 4 is a photocatalytic oxidation unit, 5 is a photocatalytic hydrogen production unit, 6 is a hydrothermal reactor, 7 is a solid-liquid separation device, 8 is an anaerobic digestion unit, 9 is a methane combined reforming unit, 10 is a CO collection device, and 11 is an H2 collection device). DETAILED DESCRIPTION

[0035] The present invention provides a photocatalytic kitchen waste hydrogen production system, which includes the following devices: a garbage crushing device, a leachate collection device, a hydrolysis reactor, a photocatalytic oxidation unit, a photocatalytic hydrogen production unit, a hydrothermal reactor, a solid-liquid separation device, an anaerobic digestion unit, a methane combined reforming unit, a CO collection device and an H2 collection device.

[0036] The present invention also provides an operating method of the kitchen waste hydrogen production system, comprising the following steps:

[0037] (1) Grinding the kitchen waste in a garbage crushing device to obtain a solid phase and leachate;

[0038] (2) hydrothermally carbonizing a portion of the solid phase in a hydrothermal reactor to obtain hydrothermal charcoal and a liquid phase;

[0039] (3) mixing the hydrothermal charcoal and the remaining solid phase in a hydrolysis reactor for hydrolysis to obtain small molecular organic matter;

[0040] (4) mixing small molecule organic matter and a tantalum-ceria catalyst in a photocatalytic oxidation unit under an oxygen atmosphere to react and produce compounds, water vapor, and carbon dioxide;

[0041] (5) mixing the compound and a titanium dioxide catalyst in a photocatalytic hydrogen production unit under a nitrogen atmosphere to react and produce hydrogen, carbon dioxide, and other organic matter;

[0042] (6) digesting the leachate from step (1), the liquid phase from step (2), and other organic matter from step (5) in an anaerobic digestion unit to produce carbon dioxide and methane;

[0043] (7) The water vapor and carbon dioxide in step (4), the carbon dioxide in step (5), and the carbon dioxide and methane in step (6) are mixed in a methane combined reforming unit for reaction to obtain carbon monoxide and hydrogen.

[0044] In the present invention, the leachate in step (1) is collected using a leachate collecting device and then fed into the anaerobic digestion unit in step (6).

[0045] In the present invention, the product obtained by hydrothermal carbonization in step (2) is passed through a solid-liquid separation device to obtain hydrothermal carbon and a liquid phase.

[0046] In the present invention, the mass ratio of the partial solid phase in step (2) to the remaining solid phase in step (3) is preferably 1:3.5-4.5, more preferably 1:3.7-4.3, and even more preferably 1:3.8-4.

[0047] In the present invention, the temperature of the hydrothermal carbonization in step (2) is preferably 200-220°C, more preferably 205-215°C, and more preferably 208-210°C; the time is preferably 11-13h, more preferably 11.5-12.5h, and more preferably 12-12.3h.

[0048] In the present invention, the hydrolysis in step (3) is carried out with the assistance of ultrasound, and the frequency of the ultrasound is preferably 15-25 kHz, more preferably 17-23 kHz, and more preferably 18-20 kHz; the temperature of the hydrolysis is preferably 30-40°C, more preferably 32-38°C, and more preferably 33-35°C; the rotation speed is preferably 0.3-0.9 r / min, more preferably 0.5-0.8 r / min, and more preferably 0.6-0.7 r / min; the time is preferably 44-52 h, more preferably 46-50 h, and more preferably 47-49 h.

[0049] In the present invention, the method for preparing the tantalum-ceria catalyst in step (4) preferably comprises the following steps:

[0050] Cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol are mixed, reacted and calcined in sequence to obtain the tantalum-ceria catalyst.

[0051] In the present invention, the concentration of the aqueous ammonia solution is preferably 7 to 8 mmol / L, more preferably 7.2 to 7.8 mmol / L, and even more preferably 7.3 to 7.5 mmol / L.

[0052] In the present invention, the mass volume ratio of the cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol is preferably 4-5 g:35-36 mg:90-110 mL:290-310 mL:70-90 mL, more preferably 4.2-4.7 g:35.2-35.8 mg:95-105 mL:295-305 mL:75-85 mL, and more preferably 4.3-4.5 g:35.3-35.5 mg:97-100 mL:297-300 mL:77-80 mL.

[0053] In the present invention, the mixing is preferably performed by preliminarily mixing cerium nitrate hexahydrate, tantalum pentachloride and ethanol, then mixing the obtained solution with an ammonia solution, centrifuging, and finally dispersing the slurry obtained by centrifugation in ethylene glycol to complete the mixing.

[0054] In the present invention, the centrifugal speed is preferably 5500-6500 r / min, more preferably 5700-6300 r / min, more preferably 6000-6100 r / min; the centrifugal time is preferably 25-35 min, more preferably 27-33 min, more preferably 28-30 min.

[0055] In the present invention, the reaction temperature is preferably 140-160° C., more preferably 145-155° C., more preferably 147-150° C.; the reaction time is preferably 44-52 h, more preferably 46-50 h, more preferably 47-49 h.

[0056] In the present invention, after the reaction is completed, the system is cooled naturally, and then washed with water and dried in sequence, and then calcined.

[0057] In the present invention, the target temperature of natural cooling is preferably 20-30°C, more preferably 22-28°C, and more preferably 23-25°C; the target pH of water washing is preferably 7-7.5, more preferably 7.1-7.4, and more preferably 7.2-7.3; the drying temperature is preferably 95-105°C, more preferably 97-103°C, and more preferably 98-100°C; the drying time is preferably 11-13h, more preferably 11.5-12.5h, and more preferably 12-12.3h.

[0058] In the present invention, the heating rate of the calcination is preferably 8 to 12°C / min, more preferably 9 to 11°C / min, and more preferably 9.5 to 10°C / min; the target temperature is preferably 380 to 420°C, more preferably 390 to 410°C, and more preferably 395 to 400°C; the holding time after reaching the target temperature is preferably 1.5 to 2.5h, more preferably 1.7 to 2.3h, and more preferably 2 to 2.2h.

[0059] In the present invention, the mass ratio of the small molecule organic matter and the tantalum-ceria catalyst in step (4) is preferably 4.5-5.5:3.5-4.5, more preferably 4.7-5.3:3.7-4.3, and more preferably 5-5.1:4-4.1; the reaction is carried out under light irradiation, preferably by providing light and heat with a Fresnel lens, and the reaction temperature is preferably 95-105°C, more preferably 97-103°C, and more preferably 98-100°C, until the reaction is complete.

[0060] In the present invention, the compound in step (4) comprises C1 compound (formic acid, formaldehyde) and other compounds, and the mass fraction of C1 compound in the compound is preferably 60-80%, more preferably 65-75%, and even more preferably 67-70%.

[0061] In the present invention, the titanium dioxide catalyst in step (5) is preferably obtained by calcining Degussa P25 photocatalyst, and the calcination temperature is preferably 550-650°C, more preferably 570-630°C, and more preferably 580-600°C; the calcination time is preferably 5.5-6.5h, more preferably 5.7-6.3h, and more preferably 6-6.2h.

[0062] In the present invention, the mass ratio of the compound in step (5) to the titanium dioxide catalyst is preferably 45 to 55:1, more preferably 47 to 53:1, and more preferably 50 to 51:1; the reaction is carried out under the conditions of light irradiation and water circulation, and the reaction temperature is preferably 20 to 30°C, more preferably 22 to 28°C, and more preferably 23 to 25°C, until the reaction is complete.

[0063] In the present invention, the mass ratio of the leachate in step (1) and the liquid phase in step (2) to the mass ratio of other organic matter in step (5) in the anaerobic digestion unit is preferably 4.5-5.5:1.5-2.5, more preferably 4.7-5.3:1.7-2.3, and more preferably 5-5.1:2-2.1; the temperature of the digestion in step (6) is preferably 36-38°C, more preferably 36.5-37.5°C, and more preferably 37-37.3°C; the time is preferably 23-25 ​​days, more preferably 23.5-24.5 days, and more preferably 23.7-24 days.

[0064] In the present invention, the mass ratio of methane, carbon dioxide and water vapor in the methane combined reforming unit is preferably 3.5-4.5:3.5-4.5:0.5-1.5, more preferably 3.7-4.3:3.7-4.3:0.7-1.3, and more preferably 3.9-4:3.9-4:0.9-1; the reaction temperature in step (7) is preferably 800-1100°C, more preferably 900-1000°C, and more preferably 920-950°C, until the reaction is complete.

[0065] In the present invention, the addition of water vapor in the methane combined reforming unit causes a wet reforming reaction between unconverted methane and water vapor, thereby reducing and inhibiting the occurrence of carbon deposition and improving the H2 yield.

[0066] In the present invention, the carbon monoxide and hydrogen obtained in the operation method are collected by a CO collection device and an H2 collection device respectively.

[0067] In the present invention, the schematic diagram of the photocatalytic kitchen waste hydrogen production system is as follows: Figure 1 As shown, 1 is a garbage crushing device, 2 is a leachate collecting device, 3 is a hydrolysis reactor, 4 is a photocatalytic oxidation unit, 5 is a photocatalytic hydrogen production unit, 6 is a hydrothermal reactor, 7 is a solid-liquid separation device, 8 is an anaerobic digestion unit, 9 is a methane combined reforming unit, 10 is a CO collecting device, and 11 is a H2 collecting device.

[0068] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0069] Example 1

[0070] 4.5 g of cerium nitrate hexahydrate, 35.5 mg of tantalum pentachloride and 100 mL of ethanol were mixed, and the resulting solution was then mixed with 300 mL of 7.5 mmol / L ammonia solution, centrifuged at 6000 r / min for 30 min, and the slurry obtained by centrifugation was dispersed in 80 mL of ethylene glycol. The mixture was reacted at 150°C for 48 h. After the reaction, the system was naturally cooled to 25°C, and then washed with water to a pH of 7. After washing, the mixture was dried at 100°C for 12 h, and finally heated to 400°C at a heating rate of 10°C / min and kept warm for 2 h to obtain a tantalum-ceria catalyst. The Degussa P25 photocatalyst was calcined at 600°C for 6 h to obtain a titanium dioxide catalyst.

[0071] The kitchen waste is crushed in a garbage crushing device to obtain a solid phase and a leachate; the leachate is collected using a leachate collecting device; part of the solid phase (the mass ratio of part of the solid phase to the remaining solid phase is 1:4) is hydrothermally carbonized at 210°C in a hydrothermal reactor for 12 hours to obtain hydrothermal char and a liquid phase; the hydrothermal char and the remaining solid phase are mixed and placed in a hydrolysis reactor, and hydrolyzed for 48 hours under the conditions of an ultrasonic frequency of 20kHz, a temperature of 35°C, and a rotation speed of 0.6r / min to obtain small molecule organic matter; in an oxygen atmosphere and light irradiation (a Fresnel lens is used to provide light and heat), the small molecule organic matter and a tantalum-cerium dioxide catalyst (the mass ratio of the small molecule organic matter to the tantalum-cerium dioxide catalyst is 5:4) are mixed, and reacted at 100°C in a photocatalytic oxidation unit to obtain a compound after the reaction is complete (the compound includes a C1 compound (formic acid, formaldehyde) and other compounds, and the C1 compound The mass fraction of the compound is 70%), water vapor and carbon dioxide; under a nitrogen atmosphere, the compound and a titanium dioxide catalyst (the mass ratio of the compound to the titanium dioxide catalyst is 50:1) are mixed in a photocatalytic hydrogen production unit at 25°C for reaction, and hydrogen, carbon dioxide and other organic matter are obtained after the reaction is complete; the leachate, liquid phase and other organic matter obtained above (the mass ratio of the sum of the mass of the leachate and the liquid phase to the mass of other organic matter is 5:2) are digested in an anaerobic digestion unit at 37°C for 24 days to obtain carbon dioxide and methane; the water vapor, carbon dioxide and methane obtained above (the mass ratio of methane, carbon dioxide and water vapor is 4:4:1) are mixed in a methane combined reforming unit at 950°C for reaction, and carbon monoxide and hydrogen are obtained after the reaction is complete. The carbon monoxide and hydrogen obtained in the entire operation method are collected by a CO collection device and an H2 collection device, respectively.

[0072] In this embodiment, by the time of the photocatalytic hydrogen production step, the yield of the obtained hydrogen is 2.5 times the yield of hydrogen produced directly without photocatalytic oxidation.

[0073] In this embodiment, in the anaerobic digestion step, the CO2 conversion rate is as high as 83%, and the H2 / CO ratio is as high as 3.7.

[0074] Example 2

[0075] 4.3 g of cerium nitrate hexahydrate, 35.3 mg of tantalum pentachloride and 97 mL of ethanol were mixed, and the resulting solution was then mixed with 297 mL of 7.3 mmol / L ammonia solution, centrifuged at 5500 r / min for 35 min, and the slurry obtained by centrifugation was dispersed in 77 mL of ethylene glycol. The reaction was carried out at 145°C for 50 h. After the reaction, the system was naturally cooled to 30°C, and then washed with water to a pH of 7.2. After washing, it was dried at 95°C for 13 h, and finally heated to 390°C at a heating rate of 9°C / min and kept warm for 2.2 h to obtain a tantalum-ceria catalyst. The Degussa P25 photocatalyst was calcined at 580°C for 6.2 h to obtain a titanium dioxide catalyst.

[0076] The kitchen waste is crushed in a garbage crushing device to obtain a solid phase and a leachate; the leachate is collected using a leachate collecting device; a portion of the solid phase (the mass ratio of the portion of the solid phase to the remaining solid phase is 1:3.8) is hydrothermally carbonized at 200°C in a hydrothermal reactor for 13 hours to obtain hydrothermal char and a liquid phase; the hydrothermal char and the remaining solid phase are mixed and placed in a hydrolysis reactor, and hydrolyzed for 49 hours under the conditions of an ultrasonic frequency of 15kHz, a temperature of 32°C, and a rotation speed of 0.5r / min to obtain small molecule organic matter; in an oxygen atmosphere and light irradiation (a Fresnel lens is used to provide light and heat), the small molecule organic matter and a tantalum-cerium oxide catalyst (the mass ratio of the small molecule organic matter to the tantalum-cerium oxide catalyst is 5.3:4.1) are mixed, and reacted at 95°C in a photocatalytic oxidation unit to obtain a compound after the reaction is complete (the compound contains C1 compound (formic acid, formaldehyde) and other compounds, and the mass of the C1 compound is The method comprises the following steps: mixing the compound and a titanium dioxide catalyst (the mass ratio of the compound to the titanium dioxide catalyst is 47:1) in a nitrogen atmosphere in a photocatalytic hydrogen production unit for reaction at 23°C, and obtaining hydrogen, carbon dioxide and other organic matter after completion of the reaction; digesting the aforementioned leachate, liquid phase and other organic matter (the mass ratio of the sum of the mass of the leachate and the liquid phase to the mass of other organic matter is 5.3:2.1) in an anaerobic digestion unit at 36°C for 25 days to obtain carbon dioxide and methane; mixing the aforementioned water vapor, carbon dioxide and methane (the mass ratio of methane, carbon dioxide and water vapor is 3.7:3.7:0.7) in a methane combined reforming unit for reaction at 900°C, and obtaining carbon monoxide and hydrogen after completion of the reaction. The carbon monoxide and hydrogen obtained in the entire operation method are collected by a CO collection device and an H2 collection device, respectively.

[0077] In this embodiment, by the time of the photocatalytic hydrogen production step, the yield of the obtained hydrogen is 2.47 times the hydrogen yield of direct hydrogen production without photocatalytic oxidation.

[0078] In this embodiment, in the anaerobic digestion step, the CO2 conversion rate is as high as 82.5%, and the H2 / CO ratio is as high as 3.6.

[0079] Example 3

[0080] 4.7 g of cerium nitrate hexahydrate, 35.8 mg of tantalum pentachloride and 105 mL of ethanol were mixed, and the resulting solution was then mixed with 305 mL of 7.8 mmol / L ammonia solution, centrifuged at 6500 r / min for 25 min, and the slurry obtained by centrifugation was dispersed in 85 mL of ethylene glycol. The mixture was reacted at 160°C for 44 h. After the reaction, the system was naturally cooled to 28°C, and then washed with water to a pH of 7.1. After washing, the system was dried at 105°C for 11 h, and finally heated to 420°C at a heating rate of 12°C / min and kept warm for 1.5 h to obtain a tantalum-ceria catalyst. The Degussa P25 photocatalyst was calcined at 650°C for 5.5 h to obtain a titanium dioxide catalyst.

[0081] The kitchen waste is crushed in a garbage crushing device to obtain a solid phase and a leachate; the leachate is collected using a leachate collecting device; a portion of the solid phase (the mass ratio of the portion of the solid phase to the remaining solid phase is 1:4.3) is hydrothermally carbonized at 220°C in a hydrothermal reactor for 11 hours to obtain hydrothermal char and a liquid phase; the hydrothermal char and the remaining solid phase are mixed and placed in a hydrolysis reactor, and hydrolyzed for 44 hours under the conditions of an ultrasonic frequency of 25kHz, a temperature of 40°C, and a rotation speed of 0.9r / min to obtain small molecule organic matter; in an oxygen atmosphere and light irradiation (a Fresnel lens is used to provide light and heat), the small molecule organic matter and a tantalum-cerium oxide catalyst (the mass ratio of the small molecule organic matter to the tantalum-cerium oxide catalyst is 4.7:3.7) are mixed, and reacted at 105°C in a photocatalytic oxidation unit to obtain a compound after the reaction is complete (the compound contains C1 compound (formic acid, formaldehyde) and other compounds, and the mass of the C1 compound is The method comprises the following steps: mixing the compound and a titanium dioxide catalyst (the mass ratio of the compound to the titanium dioxide catalyst is 53:1) in a nitrogen atmosphere in a photocatalytic hydrogen production unit for reaction at 28° C., and obtaining hydrogen, carbon dioxide and other organic matter after completion of the reaction; digesting the aforementioned leachate, liquid phase and other organic matter (the mass ratio of the sum of the mass of the leachate and the liquid phase to the mass of other organic matter is 4.7:1.7) in an anaerobic digestion unit at 38° C. for 23 days to obtain carbon dioxide and methane; mixing the aforementioned water vapor, carbon dioxide and methane (the mass ratio of methane, carbon dioxide and water vapor is 4.3:4.3:1.3) in a methane combined reforming unit for reaction at 1000° C., and obtaining carbon monoxide and hydrogen after completion of the reaction. The carbon monoxide and hydrogen obtained in the entire operation method are collected by a CO collection device and an H2 collection device, respectively.

[0082] In this embodiment, by the time of the photocatalytic hydrogen production step, the yield of the obtained hydrogen is 2.52 times the hydrogen yield of direct hydrogen production without photocatalytic oxidation.

[0083] In this embodiment, in the anaerobic digestion step, the CO2 conversion rate is as high as 81.5%, and the H2 / CO ratio is as high as 3.57.

[0084] As can be seen from the above examples, the present invention provides a photocatalytic hydrogen production system from food waste, comprising the following devices: a waste pulverizer, a leachate collection device, a hydrolysis reactor, a photocatalytic oxidation unit, a photocatalytic hydrogen production unit, a hydrothermal reactor, a solid-liquid separation unit, an anaerobic digestion unit, a methane reforming unit, a CO collection device, and an H2 collection device. The overall system boasts a rational design, significantly improving the efficiency of photocatalytic hydrogen production from food waste while rationally utilizing leachate, ultimately achieving highly efficient hydrogen production from food waste.

[0085] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A photocatalytic kitchen waste hydrogen production system, characterized in that: It includes the following devices: garbage crushing device, leachate collection device, hydrolysis reactor, photocatalytic oxidation unit, photocatalytic hydrogen production unit, hydrothermal reactor, solid-liquid separation device, anaerobic digestion unit, methane combined reforming unit, CO collection device and H2 collection device; The operation method of the kitchen waste hydrogen production system is as follows: (1) Grinding the kitchen waste in a garbage crushing device to obtain a solid phase and leachate; (2) hydrothermally carbonizing a portion of the solid phase in a hydrothermal reactor to obtain hydrothermal charcoal and a liquid phase; (3) mixing the hydrothermal charcoal and the remaining solid phase in a hydrolysis reactor for hydrolysis to obtain small molecular organic matter; (4) mixing small molecule organic matter and a tantalum-cerium oxide catalyst in a photocatalytic oxidation unit under an oxygen atmosphere to react and produce compounds, water vapor, and carbon dioxide; (5) mixing the compound and a titanium dioxide catalyst in a photocatalytic hydrogen production unit under a nitrogen atmosphere to react and produce hydrogen, carbon dioxide, and other organic matter; (6) digesting the leachate from step (1), the liquid phase from step (2), and other organic matter from step (5) in an anaerobic digestion unit to produce carbon dioxide and methane; (7) mixing the water vapor and carbon dioxide in step (4), the carbon dioxide in step (5), and the carbon dioxide and methane in step (6) in a methane combined reforming unit to react to produce carbon monoxide and hydrogen; The leachate in step (1) is collected using a leachate collection device and then fed into the anaerobic digestion unit in step (6); In step (2), the product obtained by hydrothermal carbonization is passed through a solid-liquid separation device to obtain hydrothermal carbon and a liquid phase; The carbon monoxide and hydrogen obtained during the operation are collected by a CO collection device and a H2 collection device respectively.

2. The method for operating the kitchen waste hydrogen production system according to claim 1, characterized in that: It includes the following steps: (1) Grinding the kitchen waste in a garbage crushing device to obtain a solid phase and leachate; (2) hydrothermally carbonizing a portion of the solid phase in a hydrothermal reactor to obtain hydrothermal charcoal and a liquid phase; (3) mixing the hydrothermal charcoal and the remaining solid phase in a hydrolysis reactor for hydrolysis to obtain small molecular organic matter; (4) mixing small molecule organic matter and a tantalum-cerium oxide catalyst in a photocatalytic oxidation unit under an oxygen atmosphere to react and produce compounds, water vapor, and carbon dioxide; (5) mixing the compound and a titanium dioxide catalyst in a photocatalytic hydrogen production unit under a nitrogen atmosphere to react and produce hydrogen, carbon dioxide, and other organic matter; (6) digesting the leachate from step (1), the liquid phase from step (2), and other organic matter from step (5) in an anaerobic digestion unit to produce carbon dioxide and methane; (7) The water vapor and carbon dioxide in step (4), the carbon dioxide in step (5), and the carbon dioxide and methane in step (6) are mixed in a methane combined reforming unit for reaction to obtain carbon monoxide and hydrogen.

3. The operating method according to claim 2, characterized in that: The mass ratio of the partial solid phase in step (2) to the remaining solid phase in step (3) is 1:3.5-4.

5.

4. The operating method according to claim 3, characterized in that: The hydrothermal carbonization temperature in step (2) is 200-220° C. and the time is 11-13 hours; The hydrolysis temperature in step (3) is 30-40° C., the rotation speed is 0.3-0.9 r / min, and the time is 44-52 h.

5. The operating method according to claim 4, characterized in that: The preparation method of the tantalum-cerium dioxide catalyst in step (4) comprises the following steps: Cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol are mixed, reacted and calcined in sequence to obtain the tantalum-ceria catalyst.

6. The operating method according to claim 5, characterized in that: The concentration of the ammonia solution is 7 to 8 mmol / L; The mass volume ratio of the cerium nitrate hexahydrate, tantalum pentachloride, ethanol, ammonia solution and ethylene glycol is 4-5 g: 35-36 mg: 90-110 mL: 290-310 mL: 70-90 mL.

7. The operating method according to claim 5 or 6, characterized in that: The reaction temperature is 140-160°C and the reaction time is 44-52h; The heating rate of the calcination is 8-12° C. / min, the target temperature is 380-420° C., and the holding time after reaching the target temperature is 1.5-2.5 hours.

8. The operating method according to claim 7, characterized in that: In step (4), the mass ratio of the small molecule organic compound to the tantalum-cerium dioxide catalyst is 4.5-5.5:3.5-4.5, and the reaction temperature is 95-105° C.; The mass ratio of the compound and the titanium dioxide catalyst in step (5) is 45-55:1, and the reaction temperature is 20-30°C.

9. The operating method according to claim 8, characterized in that: In the anaerobic digestion unit, the mass ratio of the leachate in step (1) and the liquid phase in step (2) to the mass ratio of the other organic matter in step (5) is 4.5-5.5:1.5-2.5; the digestion temperature in step (6) is 36-38° C. and the digestion time is 23-25 ​​days.

10. The operating method according to claim 9, characterized in that: The mass ratio of methane, carbon dioxide and water vapor in the methane combined reforming unit is 3.5-4.5:3.5-4.5:0.5-1.5; the temperature of the reaction in step (7) is 800-1100°C.

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