Method for producing hydrogen from corn straw electric enzymatic hydrolysate based on sectional type electric pretreatment device

Abstract

The invention relates to the technical field of biomass dark fermentation hydrogen production, and discloses a corn straw electric enzymatic hydrolysate hydrogen production method based on a sectional type electric pretreatment device, which comprises a pretreatment device shell, and a pretreatment cavity is arranged in the pretreatment device shell; a straw electric enzymatic hydrolysate is stored in the pretreatment cavity; the pretreatment electrode is arranged in the pretreatment cavity, and the straw electric enzymatic hydrolysate is subjected to strong electric field electric pretreatment and weak electric field electric pretreatment by adjusting the pretreatment electrode; comprising the following steps: mixing corn straws with a citric acid-sodium citrate buffer solution, and putting the mixture into a pretreatment cavity for strong current pretreatment; after the strong current pretreatment is completed, cellulase is added into the pretreatment cavity, and weak current enhanced cellulose enzymolysis is carried out; and after the sectional type electric pretreatment is finished, carrying out mixed fermentation on the filtered electricity-taking enzymatic hydrolysate and hydrogenogens to produce hydrogen. The problems of crusting, coking, difficulty in pH control, difficulty in straw residue recovery and the like in the traditional corn straw fermentation process are solved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production by dark fermentation of biomass, and in particular to a method for producing hydrogen by electrolytic hydrolysis of corn stalks based on a segmented electric pretreatment device. Background Art

[0002] With the rapid development of social economy, fossil energy is increasingly in short supply, carbon emissions are also rising, and we are facing two major problems: resource depletion and environmental pollution. At the same time, most corn stalks are not effectively utilized. Some are randomly dumped in the fields, causing insects and mold to damage the soil, and the other part is directly burned, causing serious air pollution and smog. Dark fermentation hydrogen production technology can use resources such as straw to produce hydrogen, which is an effective way to realize biomass resource utilization and clean resource scale.

[0003] Enzyme hydrolysate fermentation technology is a dark fermentation technology that uses different enzymes to break the complex hydrogen bond structure of corn straw and degrade lignin, cellulose, hemicellulose and reducing sugars into electrolytic hydrolysate. This technology has problems such as low straw utilization and low sugar degradation efficiency. How to solve this problem is very critical.

[0004] Therefore, there is an urgent need for a method for producing hydrogen from corn straw electrolyzed liquid based on a segmented electrical pretreatment device to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a method for producing hydrogen from corn straw electrolyzed liquid based on a segmented electrical pretreatment device, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solution: The present invention provides a segmented electrical pretreatment device, comprising:

[0007] A pretreatment device housing, wherein a pretreatment cavity is disposed in the pretreatment device housing; and a straw electrolytic enzymatic solution is stored in the pretreatment cavity;

[0008] The pretreatment electrode is arranged in the pretreatment chamber, and the strong electric field pretreatment and the weak electric field pretreatment are performed on the straw electrolytic solution by adjusting the pretreatment electrode.

[0009] Preferably, the pretreatment electrode comprises an anode electrode and a plurality of cathode electrodes, the anode electrode being installed at the exact center of the pretreatment chamber, and the plurality of cathode electrodes being installed at equal intervals in the circumferential direction in the pretreatment chamber with gaps between the anode electrode and the cathode electrodes.

[0010] Preferably, a plurality of stirring devices are installed in the pretreatment chamber along the circumferential direction, and the stirring devices are located in the gap.

[0011] Preferably, a heat-insulating layer is provided in the pretreatment chamber, a water inlet and a water outlet are provided on the heat-insulating layer, and the water inlet and the water outlet are connected to an external hot water heater.

[0012] Preferably, a feed inlet, a discharge outlet, a pH sensor and a temperature sensor are provided on the housing of the pretreatment device.

[0013] Preferably, the size of the anode electrode is Φ400mm*880mm, the size of the cathode electrode is 100*400*880mm, and the spacing of the gap is 1000mm.

[0014] The method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device comprises the following steps:

[0015] Mixing corn stalks with citric acid-sodium citrate buffer and placing them into the pretreatment chamber for high-voltage pretreatment;

[0016] After the strong current pretreatment is completed, cellulase is added into the pretreatment chamber to perform weak current enhanced cellulose enzymolysis;

[0017] After the segmented electrical pretreatment is completed, the electrolytic solution is filtered and mixed with hydrogen-producing bacteria for fermentation to produce hydrogen.

[0018] Preferably, the strong electric field pretreatment voltage is 700 V / m, the pretreatment time is 2.5 h, and stirring is performed every 15 min, and each stirring time is 2 min.

[0019] Preferably, the weak electric field pretreatment voltage is 16 V / m, the pretreatment time is 48 h, and stirring is performed every 4 h, and each stirring time is 10 min.

[0020] Preferably, after the electrolytic pretreatment is completed, the electrolytic solution is separated into solid and liquid, and 500 mL of the electrolytic solution after solid-liquid separation is taken and combined with 500 mL of hydrogen-producing bacteria, and the pH is adjusted to 7.0±0.1 by adding sodium bicarbonate, and nitrogen is used for 5 minutes of explosion, and the gas production is collected and the gas composition is analyzed.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects:

[0022] The invention provides a method for producing hydrogen from corn straw electrolytic solution based on a segmented electric pretreatment device. The pretreatment electrodes provided by the invention perform strong electric field electric pretreatment and weak electric field electric pretreatment on the straw electrolytic solution. The strong electric field destroys the external barriers such as the lignin layer and cell membrane of the corn straw, breaks the hydrogen bond structure of the corn straw, reduces the crystallinity and specific surface area, triggers the release of intracellular substances, and makes the contact between the microorganism and the degradable substance more complete. The weak electric field strengthens the coupling of cellulase with the straw treated with the strong electric field, and accelerates the degradation of sugars, tri-element and other substances in the corn straw. The invention designs a segmented electric pretreatment device. The high electric field intensity promotes the destruction of the straw structure, and the low electric field intensity promotes the cellulase to degrade the straw substance, so as to realize the efficient pretreatment of the corn straw. The straw electrolytic solution after the segmented electric field pretreatment contains a variety of substances. Directly utilizing these substances to produce hydrogen can shorten the hydrogen production cycle of the corn straw, increase the gas production, and avoid the problem of rapid pH drop caused by directly utilizing the straw and other substances to degrade sugars. The present application solves the problems of crusting, coking, difficulty in controlling pH, and difficulty in recycling corn straw residues during the traditional corn straw fermentation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0024] Figure 1 This is a front view of the segmented electrical pretreatment device of the present invention;

[0025] Figure 2 It is a top view of the segmented electrical pretreatment device of the present invention;

[0026] Figure 3 This is an electron microscope scanning image of corn stalks before pretreatment of the present invention;

[0027] Figure 4 This is an electron microscope scanning image of corn stalks after pretreatment according to the present invention;

[0028] Figure 5 This is a comparison diagram of the cumulative hydrogen production of the electrolytic solution after electrical pretreatment and without electrical pretreatment of the present invention;

[0029] Among them, 1. pretreatment electrode; 101. anode electrode; 102. cathode electrode; 2. stirring device; 3. insulation layer; 4. pretreatment chamber; 5. pretreatment device housing; 6. water inlet; 7. water outlet; 8. feed inlet; 9. discharge outlet; 10. pH sensor; 11. temperature sensor. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figure 1-Figure 5 The present invention provides a segmented electrical pretreatment device, comprising:

[0033] A pretreatment device housing 5, wherein a pretreatment chamber 4 is disposed in the pretreatment device housing 5; and the pretreatment chamber 4 stores straw electrolytic enzyme solution;

[0034] The pretreatment electrode 1 is arranged in the pretreatment chamber 4, and the straw electrolyzed liquid is subjected to strong electric field pretreatment and weak electric field pretreatment by adjusting the pretreatment electrode 1.

[0035] According to a further optimization scheme, the pretreatment electrode 1 includes an anode electrode 101 and a plurality of cathode electrodes 102 . The anode electrode 101 is installed in the center of the pretreatment chamber 4 , and the plurality of cathode electrodes 102 are installed in the pretreatment chamber 4 at equal intervals along the circumferential direction, and gaps are set between the anode electrode 101 .

[0036] In one embodiment of the present invention, the number of the anode electrode 101 is one, and the number of the cathode electrodes 102 is preferably four.

[0037] According to a further optimized solution, a plurality of stirring devices 2 are installed in the pretreatment chamber 4 along the circumferential direction, and the stirring devices 2 are located in the gaps.

[0038] In one embodiment of the present invention, the number of stirring devices 2 corresponds to the number of cathode electrodes 102, and is used to stir the internal solution.

[0039] According to a further optimization scheme, a heat preservation layer 3 is provided in the pretreatment chamber 4, a water inlet 6 and a water outlet 7 are provided on the heat preservation layer 3, and the water inlet 6 and the water outlet 7 are connected to an external hot water heater.

[0040] In one embodiment of the present invention, the water inlet 6 and the water outlet 7 can be connected to an external hot water heater. Hot water is injected into the insulation layer 3 through the water inlet 6 and discharged into the external hot water heater through the water outlet 7 for cyclic heating to provide suitable temperature conditions for electrical pretreatment.

[0041] According to a further optimized solution, a feed port 8, a discharge port 9, a pH sensor 10 and a temperature sensor 11 are provided on the housing 5 of the pretreatment device.

[0042] In one embodiment of the present invention, the feed liquid enters the pretreatment chamber 4 from the feed port 8 and is discharged from the discharge port 9 for solid-liquid separation. The pH sensor 10 and the temperature sensor 11 are used to monitor the pH and temperature changes in real time during the pretreatment process.

[0043] According to a further optimization scheme, the size of the anode electrode 101 is Φ400mm*880mm, the size of the cathode electrode 102 is 100*400*880mm, and the spacing of the gap is 1000mm.

[0044] In one embodiment of the present invention, corn stalks and electrolytic solution are placed in the pretreatment chamber 4, the whole device is cylindrical, and the filling volume is 4 / 5 of the total volume.

[0045] The method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device comprises the following steps:

[0046] The corn stalks are mixed with citric acid-sodium citrate buffer and placed in the pretreatment chamber 4 for strong electric pretreatment;

[0047] After the strong current pretreatment is completed, cellulase is added into the pretreatment chamber 4 to perform weak current enhanced cellulose enzymolysis;

[0048] After the segmented electrical pretreatment is completed, the electrolytic solution is filtered and mixed with hydrogen-producing bacteria for fermentation to produce hydrogen.

[0049] The scheme was further optimized, with a strong electric field pretreatment voltage of 700 V / m, a pretreatment time of 2.5 h, and stirring every 15 min, with each stirring time of 2 min.

[0050] In one embodiment of the present invention, 43.5 g / L corn stalks and a citric acid-sodium citrate buffer with a pH of 5 are mixed and added into a pretreatment chamber 4 through a feed port 8, and a strong electric pretreatment is started. The voltage is adjusted to 700 V / m, and the strong electric pretreatment is performed for 2.5 hours through an anode electrode 101 and a cathode electrode 102. The mixture is stirred every 15 minutes through a stirring device 2, and each stirring time is 2 minutes. The pH and temperature are monitored through a pH sensor 10 and a temperature sensor 11 to break the hydrogen bond network structure of the corn stalks and destroy the external structure of the stalks.

[0051] Furthermore, hot circulating water is injected into the thermal insulation layer 3 through the water inlet 6 and the water outlet 7 to maintain the temperature in the pretreatment chamber 4 at 50±1°C.

[0052] The scheme was further optimized, with a weak electric field pretreatment voltage of 16 V / m, a pretreatment time of 48 h, and stirring every 4 h, with each stirring time of 10 min.

[0053] In one embodiment of the present invention, after strong current pretreatment, the voltage is adjusted to 16V / m, and a straw cellulase with a unit of 20 units / mg and a mass of 0.2g / g is added to the pretreatment chamber 4. The weak current pretreatment time is 8h, stirring is performed every 4h, and each stirring time is 10min. The weak current enhanced cellulose enzymatic hydrolysis process is performed. After the strong current pretreatment, the straw is obtained, because its external structure is destroyed, and the internal cellulose, hemicellulose, lignin, etc. are exposed. The enzymatic hydrolysis efficiency is greatly improved through the strengthening effect of the weak point field.

[0054] To further optimize the scheme, after the electrolytic pretreatment, solid-liquid separation of the electrolytic solution was completed, 500 mL of the electrolytic solution after solid-liquid separation was taken, combined with 500 mL of hydrogen-producing bacteria, and the pH was adjusted to 7.0±0.1 by adding sodium bicarbonate, and nitrogen was used for 5 min of explosion, and the gas production was collected and analyzed.

[0055] In one embodiment of the present invention, 500 mL of electrolytic solution after electropretreatment and solid-liquid separation is taken, combined with 500 mL of hydrogen-producing bacteria, and the pH is adjusted to 7.0±0.1 by adding sodium bicarbonate, and nitrogen is used for 5 minutes to maintain an anaerobic environment. The gas is collected by exhausting saturated sodium bicarbonate, and the gas composition is analyzed by gas chromatograph.

[0056] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0057] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A segmented electrical pretreatment device, characterized in that: include: A pretreatment device housing (5), wherein a pretreatment chamber (4) is arranged in the pretreatment device housing (5); The pretreatment cavity (4) stores straw electrolytic solution; The pretreatment electrode (1) is arranged in the pretreatment chamber (4), and the straw electrolytic solution is subjected to strong electric field pretreatment and weak electric field pretreatment by adjusting the pretreatment electrode (1).

2. A segmented electrical pretreatment device according to claim 1, characterized in that: The pretreatment electrode (1) comprises an anode electrode (101) and a plurality of cathode electrodes (102); the anode electrode (101) is installed at the exact center of the pretreatment chamber (4); and the plurality of cathode electrodes (102) are installed in the pretreatment chamber (4) at equal intervals along the circumferential direction, with gaps being provided between the cathode electrodes (102) and the anode electrode (101).

3. A segmented electrical pretreatment device according to claim 2, characterized in that: A plurality of stirring devices (2) are installed in the pretreatment chamber (4) along the circumferential direction, and the stirring devices (2) are located in the gap.

4. A segmented electrical pretreatment device according to claim 1, characterized in that: A heat-insulating layer (3) is provided in the pretreatment chamber (4), a water inlet (6) and a water outlet (7) are provided on the heat-insulating layer (3), and the water inlet (6) and the water outlet (7) are connected to an external hot water heater.

5. A segmented electrical pretreatment device according to claim 1, characterized in that: The pretreatment device housing (5) is provided with a feed port (8), a discharge port (9), a pH sensor (10) and a temperature sensor (11).

6. A segmented electrical pretreatment device according to claim 2, characterized in that: The size of the anode electrode (101) is Φ400mm*880mm, the size of the cathode electrode (102) is 100*400*880mm, and the spacing of the gap is 1000mm.

7. A method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device, which is applicable to a segmented electrical pretreatment device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Mixing corn stalks with citric acid-sodium citrate buffer solution and placing them into the pretreatment chamber (4) for high-voltage pretreatment; After the strong current pretreatment is completed, cellulase is added into the pretreatment chamber (4) to perform weak current-enhanced cellulose enzymolysis; After the segmented electrical pretreatment is completed, the electrolytic solution is filtered and mixed with hydrogen-producing bacteria for fermentation to produce hydrogen.

8. The method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device according to claim 7, characterized in that: The strong electric field pretreatment voltage was 700 V / m, the pretreatment time was 2.5 h, and stirring was performed every 15 min, with each stirring time being 2 min.

9. The method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device according to claim 7, characterized in that: The weak electric field pretreatment voltage was 16 V / m, the pretreatment time was 48 h, and stirring was performed every 4 h, with each stirring time being 10 min.

10. The method for producing hydrogen from corn straw electrolytic solution based on a segmented electrical pretreatment device according to claim 7, characterized in that: After the electrolytic pretreatment, the electrolytic solution was separated into solid and liquid. 500 mL of the electrolytic solution after solid-liquid separation was taken and combined with 500 mL of hydrogen-producing bacteria. The pH was adjusted to 7.0±0.1 by adding sodium bicarbonate. Nitrogen was used for explosion for 5 minutes, and the gas production was collected and analyzed.

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