Method for producing hydrogen

Abstract

The invention discloses a method for producing hydrogen, and belongs to the field of hydrogen production. The method comprises the following steps: mixing a polylactic acid plastic product with water and a catalyst, and reacting in a closed pressure container filled with shielding gas; the catalyst is a Raney type catalyst. Wherein the carbon yield can reach 80.5%, and the hydrogen yield can reach 62.6 mmol / gplasma. The invention provides a method for producing hydrogen by using polylactic acid plastic products (fragments, powder, cups, bags, spoons, forks and the like), the process is environment-friendly, the process is simple and convenient, the operation is easy, the treatment efficiency is high, and high-purity hydrogen is obtained.

Description

Technical Field

[0001] The present application relates to a method for producing hydrogen, and belongs to the field of hydrogen production. Background Art

[0002] In the past few decades, environmental pollution has become increasingly serious due to the massive burning of fossil fuels. Therefore, it is crucial to develop new clean energy sources. Among many new energy sources, hydrogen energy is widely produced in thermal catalysis and electrocatalysis processes due to its clean, safe and pollution-free advantages. In addition, plastic pollution is also one of the biggest environmental challenges facing the earth today. These commercial plastics made of polymers play a huge role in our daily lives, but the natural degradation of these plastics often takes hundreds of years, which causes their accumulation in the natural environment. Therefore, biodegradable plastics based on polylactic acid came into being. Most degradable plastics begin to thin and break after being exposed to normal environments for 3 to 6 months. Therefore, how to quickly recycle degradable plastics is a research area that needs to be explored urgently.

[0003] At present, there are two main methods proposed for producing hydrogen using waste plastics as raw materials, namely gasification and pyrolysis. Gasification refers to the process of converting waste plastics into a gas mixture through a thermochemical reaction of incomplete combustion in the temperature range of 800-1300°C using water vapor, oxygen-rich, pure oxygen or air as the gasification medium. Pyrolysis refers to the process of converting waste plastics into a gas mixture in the temperature range of 400-800°C under oxygen-deficient or oxygen-free conditions. Gasification and pyrolysis usually include two steps: one is that waste plastics are converted into raw gas through gasification / pyrolysis, and the other is that the raw gas is steam reformed on the catalyst to produce a gas mixture (H2, CO, CO2 and CH4, etc.). Both processes require higher temperatures. In addition, the catalyst is easily deactivated due to coke deposition during the steam reforming stage of the raw gas.

[0004] Therefore, high operating temperature and catalyst deactivation are the main limiting factors for hydrogen production from plastics. It is urgent to develop an efficient reaction system to reduce the reaction temperature of hydrogen production from plastics and increase the H2 content in the gas product, which is of great significance for achieving efficient degradation of plastics and hydrogen production at the same time, solving white pollution and energy shortage problems. Summary of the invention

[0005] The present invention develops a method for producing hydrogen, realizing a revolutionary technology for preparing hydrogen from polylactic acid plastic products under mild conditions, and providing important energy guarantee for the sustainable development of my country's economy.

[0006] In order to achieve the above purpose, the method adopted is to mix the polylactic acid plastic product with water and a catalyst and react in a closed pressure container filled with protective gas.

[0007] A method for producing hydrogen, comprising mixing a polylactic acid plastic product with water and a catalyst, and reacting the mixture in a sealed pressure vessel filled with a protective gas to obtain hydrogen;

[0008] The catalyst is a Raney-type catalyst.

[0009] Optionally, the Raney-type catalyst is at least one of Raney Ni, Raney Fe, Raney Ni-Al, Raney Ni-Mo, Raney Ni-Sn, Raney Ni-Fe or Raney Ni-Cu.

[0010] Optionally, the polylactic acid plastic product is at least one of fragments, powder, cups, bags, spoons, and forks.

[0011] Optionally, the volume of the water is 10-70% of the total volume of the pressure vessel.

[0012] Preferably, the volume of the water is 20-50% of the total volume of the pressure vessel.

[0013] More preferably, the volume of water is 30-40% of the total volume of the pressure vessel.

[0014] Optionally, the amount of the polylactic acid plastic product added is 1 to 20% of the mass of the water.

[0015] Preferably, the amount of the polylactic acid plastic product added is 1 to 15% of the mass of the water.

[0016] Further preferably, the amount of the polylactic acid plastic product added is 2-10% of the mass of the water.

[0017] Optionally, the added amount of the catalyst is 5-50% of the mass of the polylactic acid plastic product.

[0018] Preferably, the added amount of the catalyst is 10-40% of the mass of the polylactic acid plastic product.

[0019] Optionally, the protective gas is a nitrogen atmosphere;

[0020] The pressure of the nitrogen is 0.1-6 MPa.

[0021] Preferably, the pressure of the nitrogen is 0.5-4 MPa.

[0022] More preferably, the pressure of the nitrogen is 1-3 MPa.

[0023] Optionally, the reaction temperature is 150-350°C.

[0024] Preferably, the reaction temperature is 200-350°C.

[0025] More preferably, the reaction temperature is 250-350°C.

[0026] Optionally, the reaction time is 1 to 24 hours.

[0027] Preferably, the reaction time is 2 to 15 hours.

[0028] More preferably, the reaction time is 2 to 10 hours.

[0029] Optionally, the method further comprises the steps of separating and reusing the catalyst, and separating and reusing the reducing gas.

[0030] Specifically, the separation and reuse of the catalyst is to use a magnet to directly attract the catalyst after the reaction and further recycle it.

[0031] The above steps and methods are used to directly catalytically convert polylactic acid plastic products into hydrogen under mild conditions, with a carbon yield of 80.5% and a hydrogen output of 62.6 mmol / g. plastic , which is of great significance for achieving efficient degradation of plastics and hydrogen production at the same time, and solving the problems of white pollution and energy shortage.

[0032] The present invention provides a method for producing hydrogen using polylactic acid plastic products. The process is environmentally friendly, simple in process, easy to operate, and has high processing efficiency, and high-purity hydrogen is obtained. The present invention designs and develops an efficient catalytic reaction system that can destroy the tough structure of plastics at a relatively low temperature and catalyze the conversion of polylactic acid to directly produce hydrogen. This is of great significance for simultaneously achieving efficient degradation of plastics and hydrogen production, and solving the problems of white pollution and energy shortage.

[0033] The beneficial effects of this application include:

[0034] 1) The present invention realizes the direct conversion of polylactic acid plastic products to produce hydrogen under relatively low reaction temperature and pressure conditions. The reaction conditions are mild, so the requirements for reaction equipment are relatively low, and the invention has great industrialization potential.

[0035] 2) The catalyst used in the present invention can be directly separated and further recycled, thereby reducing the cost of the process.

[0036] 3) The method of the present invention has simple operation steps, is easy to operate, has low energy consumption, and is a green process, and is an environmentally friendly process. DETAILED DESCRIPTION

[0037] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0038] Unless otherwise specified, the raw materials and catalysts in the examples of this application were purchased through commercial channels.

[0039] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0040] The Raney-type catalysts in the embodiments of the present application: Raney Ni, Raney Fe and Raney Ni-Fe are purchased directly from Dalian General Chemical Co., Ltd., the model of Raney Ni is RTH-2110, wherein the mass contents of Ni and Al are 95.7% and 4.3% respectively, the model of Raney Fe is RTH-8110, wherein the mass contents of Fe and Al are 94.6% and 5.4% respectively, and the model of Raney Ni-Fe is RTH-3110, wherein the mass contents of Ni, Al and Fe are 93.6%, 3.0% and 3.4% respectively. In addition, Raney Ni-Al, Raney Ni-Sn, Raney Ni-Mo and Raney Ni-Cu are Ni-Al, Ni-Al-Sn, Ni-Al-Fe and Ni-Al-Cu alloy powders purchased from Dalian General Chemical Co., Ltd., and then dealuminated and activated in NaOH solution to obtain the corresponding Raney-type catalysts for catalytic reactions.

[0041] The H2 production and carbon yield in the examples of this application are calculated as follows:

[0042]

[0043]

[0044] Example 1

[0045] Cut the plastic cup made of polylactic acid into pieces, then weigh 0.2g of the plastic fragments and add them to a 50mL reactor, then add 15mL of water as the reaction solvent and 0.08g of Raney Fe as the catalyst, and stir magnetically to mix them thoroughly. Seal the reactor, replace the gas in the reactor with nitrogen 10 times, then fill the reactor with nitrogen to 1.0MPa, and close the inlet and outlet. Heat to 310℃ by electric heating under 400rpm magnetic stirring, and keep at this temperature for 300min. After the reaction is completed, stop stirring, cool the reactor to room temperature with ice water, collect the gas products after the reaction with an air bag and analyze them. Use a magnet to directly attract and separate the catalyst after the reaction, and further recycle it.

[0046] Through qualitative and quantitative analysis of the gas products, it was concluded that direct conversion of polylactic acid plastic cups could produce hydrogen, with a hydrogen yield of 16.2mmol / g plastic, the carbon yield reached 20.1%.

[0047] Example 2

[0048] Cut the plastic cup made of polylactic acid into pieces, then weigh 0.2g of the plastic fragments and add them to a 50mL reactor, then add 15mL of water as the reaction solvent and 0.1g of Raney Ni as the catalyst, and stir magnetically to mix them thoroughly. Seal the reactor, replace the gas in the reactor with nitrogen 10 times, then fill the reactor with nitrogen to 1.0MPa, and close the inlet and outlet. Heat to 310℃ by electric heating under 400rpm magnetic stirring, and keep at this temperature for 300min. After the reaction is completed, stop stirring, cool the reactor to room temperature with ice water, collect the gas products after the reaction with an air bag and analyze them. Use a magnet to directly attract and separate the catalyst after the reaction, and further recycle it.

[0049] Through qualitative and quantitative analysis of the gas products, it was concluded that direct conversion of polylactic acid plastic cups could produce hydrogen, with a hydrogen yield of 33.4mmol / g plastic , the carbon yield reached 40.5%.

[0050] Example 3

[0051] Cut the plastic cup made of polylactic acid into pieces, then weigh 0.2g of the plastic fragments and add them to a 50mL reactor, then add 15mL of water as the reaction solvent and 0.1g of Raney Ni-Fe as the catalyst, and stir magnetically to mix them thoroughly. Seal the reactor, replace the gas in the reactor with nitrogen 10 times, then fill the reactor with nitrogen to 1.0MPa, and close the inlet and outlet. Heat to 310℃ by electric heating under 400rpm magnetic stirring, and keep at this temperature for 300min. After the reaction is completed, stop stirring, cool the reactor to room temperature with ice water, collect the gas products after the reaction with an air bag and analyze them. Use a magnet to directly attract and separate the catalyst after the reaction, and further recycle it.

[0052] Through qualitative and quantitative analysis of the gas products, it was concluded that direct conversion of polylactic acid plastic cups could produce hydrogen, with a hydrogen yield of 62.6mmol / g plastic , the carbon yield reached 80.5%.

[0053] Example 4

[0054] Cut the plastic cup made of polylactic acid into pieces, then weigh 0.2g of the plastic fragments and add them to a 50mL reactor, then add 15mL of water as the reaction solvent and 0.06g of Raney Ni-Sn as the catalyst, and stir magnetically to mix them thoroughly. Seal the reactor, replace the gas in the reactor with nitrogen 10 times, then fill the reactor with nitrogen to 1.0MPa, and close the inlet and outlet. Heat to 310℃ by electric heating under 400rpm magnetic stirring, and keep at this temperature for 300min. After the reaction is completed, stop stirring, cool the reactor to room temperature with ice water, collect the gas products after the reaction with an air bag and analyze them. Use a magnet to directly attract and separate the catalyst after the reaction, and further recycle it.

[0055] Through qualitative and quantitative analysis of the gas products, it was concluded that direct conversion of polylactic acid plastic cups could produce hydrogen, with a hydrogen yield of 29.8mmol / g plastic , the carbon yield reached 37.1%.

[0056] Example 5

[0057] Cut the plastic cup made of polylactic acid into pieces, then weigh 0.2g of the plastic fragments and add them to a 50mL reactor, then add 15mL of water as the reaction solvent and 0.07g of Raney Ni-Mo as the catalyst, and stir them magnetically to mix them thoroughly. Seal the reactor, replace the gas in the reactor with nitrogen 10 times, then fill the reactor with nitrogen to 1.0MPa, and close the inlet and outlet. Heat to 310℃ by electric heating under 400rpm magnetic stirring, and keep at this temperature for 300min. After the reaction is completed, stop stirring, cool the reactor to room temperature with ice water, collect the gas products after the reaction with an air bag and analyze them. Use a magnet to directly attract and separate the catalyst after the reaction, and further recycle it.

[0058] Through qualitative and quantitative analysis of the gas products, it was concluded that direct conversion of polylactic acid plastic cups could produce hydrogen, with a hydrogen yield of 27.3mmol / g plastic , the carbon yield reached 32.4%.

[0059] Example 6

[0060] The preparation process described in Example 1 was repeated, except that the polylactic acid plastic cup was replaced with powder, and the gas product obtained was hydrogen, with a hydrogen yield of 12.1 mmol / g. plastic , the carbon yield reached 14.5%.

[0061] Example 7

[0062] The preparation process described in Example 2 was repeated, except that the polylactic acid plastic cup was replaced with powder, and the gas product obtained was hydrogen, with a hydrogen yield of 28.5 mmol / g plastic , the carbon yield reached 34.5%.

[0063] Example 8

[0064] The preparation process described in Example 3 was repeated, except that the polylactic acid plastic cup was replaced with powder, and the gas product obtained was hydrogen, with a hydrogen yield of 53.8 mmol / g plastic , the carbon yield reached 66.3%.

[0065] Example 9

[0066] The preparation process described in Example 4 was repeated, except that the polylactic acid plastic cup was replaced with powder, and the gas product obtained was hydrogen, with a hydrogen yield of 26.7 mmol / g. plastic , the carbon yield reached 34.3%.

[0067] Example 10

[0068] The preparation process described in Example 5 was repeated, except that the polylactic acid plastic cup was replaced with powder, and the gas product obtained was hydrogen, with a hydrogen yield of 25.4 mmol / g. plastic , the carbon yield reached 32.9%.

[0069] Embodiment 11

[0070] The preparation process described in Example 1 was repeated, except that the polylactic acid plastic cup was replaced with a plastic bag. The gas product obtained was hydrogen, and the hydrogen yield reached 14.3 mmol / g. plastic , the carbon yield reached 16.8%.

[0071] Example 12

[0072] The preparation process described in Example 2 was repeated, except that the polylactic acid plastic cup was replaced with a plastic bag. The gas product obtained was hydrogen, and the hydrogen yield reached 47.8 mmol / g. plastic , the carbon yield reached 58.4%.

[0073] Example 13

[0074] The preparation process described in Example 3 was repeated, except that the polylactic acid plastic cup was replaced with a plastic bag. The gas product obtained was hydrogen, and the hydrogen yield reached 21.4 mmol / g. plastic , the carbon yield reached 27.4%.

[0075] Embodiment 14

[0076] The preparation process described in Example 4 was repeated, except that the polylactic acid plastic cup was replaced with a plastic bag. The gas product obtained was hydrogen, and the hydrogen yield reached 20.9 mmol / g. plastic , the carbon yield reached 26.2%.

[0077] Embodiment 15

[0078] The preparation process described in Example 5 was repeated, except that the polylactic acid plastic cup was replaced with a plastic bag. The gas product obtained was hydrogen, and the hydrogen yield reached 25.4 mmol / g. plastic , the carbon yield reached 32.9%.

[0079] Example 16

[0080] The preparation process described in Example 1 was repeated, except that the polylactic acid plastic cup was replaced with a plastic fork and spoon, and the hydrogen production reached 11.9 mmol / g plastic , the carbon yield reached 14.5%.

[0081] Embodiment 17

[0082] The preparation process described in Example 2 was repeated, except that the polylactic acid plastic cup was replaced with a plastic fork and spoon, and the hydrogen production reached 26.4 mmol / g plastic , the carbon yield reached 32.7%.

[0083] Embodiment 18

[0084] The preparation process described in Example 3 was repeated, except that the polylactic acid plastic cup was replaced with a plastic fork and spoon, and the hydrogen production reached 49.3 mmol / g plastic , the carbon yield reached 59.8%.

[0085] Embodiment 19

[0086] The preparation process described in Example 4 was repeated, except that the polylactic acid plastic cup was replaced with a plastic fork and spoon, and the hydrogen production reached 24.5 mmol / g plastic , the carbon yield reached 29.9%.

[0087] Embodiment 20

[0088] The preparation process described in Example 5 was repeated, except that the polylactic acid plastic cup was replaced with a plastic fork and spoon, and the hydrogen production reached 22.7 mmol / g. plastic , the carbon yield reached 28.6%.

[0089] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for producing hydrogen, characterized in that: The polylactic acid plastic product is mixed with water and a catalyst, and reacted in a closed pressure vessel filled with protective gas to obtain hydrogen; The catalyst is a Raney-type catalyst.

2. The method according to claim 1, characterized in that The Raney-type catalyst is at least one of Raney Ni, Raney Fe, Raney Ni-Al, Raney Ni-Mo, Raney Ni-Sn, Raney Ni-Fe or Raney Ni-Cu.

3. The method according to claim 1, characterized in that The polylactic acid plastic product is at least one of fragments, powder, cups, bags, spoons and forks.

4. The method according to claim 1, characterized in that: The volume of the water is 10 to 70% of the total volume of the pressure vessel; Preferably, the volume of the water is 20-50% of the total volume of the pressure vessel; More preferably, the volume of water is 30-40% of the total volume of the pressure vessel.

5. The method according to claim 1, characterized in that The amount of the polylactic acid plastic product added is 1 to 20% of the mass of the water; Preferably, the amount of the polylactic acid plastic product added is 1 to 15% of the mass of the water; Further preferably, the amount of the polylactic acid plastic product added is 2-10% of the mass of the water.

6. The method according to claim 1, characterized in that The amount of the catalyst added is 5 to 50% of the mass of the polylactic acid plastic product; Preferably, the added amount of the catalyst is 10-40% of the mass of the polylactic acid plastic product.

7. The method according to claim 1, characterized in that The protective gas is a nitrogen atmosphere; The pressure of the nitrogen is 0.1-6 MPa; Preferably, the pressure of the nitrogen is 0.5-4 MPa; More preferably, the pressure of the nitrogen is 1-3 MPa.

8. The method according to claim 1, characterized in that The reaction temperature is 150-350°C; Preferably, the reaction temperature is 200-350°C; More preferably, the reaction temperature is 250-350°C.

9. The method according to claim 1, characterized in that: The reaction time is 1 to 24 hours; Preferably, the reaction time is 2 to 15 hours; More preferably, the reaction time is 2 to 10 hours.

10. The method according to claim 1, characterized in that The method further comprises the steps of separating and reusing the catalyst, and separating and reusing the reducing gas.

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