Method for preparing natural gas by taking plastic as raw material

Abstract

The invention discloses a preparation method of natural gas by taking plastic as a raw material, which comprises the following steps: mixing the raw material containing the plastic with a catalyst, and reacting in a closed container in a reducing gas atmosphere to obtain a product containing the natural gas, the plastic contains polycarbonate; the catalyst is selected from at least one of Raney Ni, Raney Ni-Mo, Raney Cu, Raney Fe, Raney Ni-Co, Raney Ni-Fe, Raney Ni-Cu, Raney Ni-Al and Raney Ni-Sn, and the catalyst is selected from at least one of Raney Ni, Raney Ni-Mo, Raney Cu, Raney Fe, Raney Ni-Co, Raney Ni-Fe, Raney Ni-Cu, Raney Ni-Al and Raney Ni-Sn. And the carbon yield of the natural gas can reach 70.2%. The waste plastic can be recycled, the demand pressure of the natural gas can be relieved, and the process is simple in technology and easy to operate and has important significance on relieving the supply and demand contradiction of the natural gas in China.

Description

Technical Field

[0001] This application relates to a method for preparing natural gas using plastic as a raw material, belonging to the field of plastic waste recycling. Background Technology

[0002] In 2023, global natural gas consumption reached 4.01 trillion cubic meters, with the year-on-year growth rate increasing from -0.4% in the previous year to 0.1%. This was mainly due to a combination of factors, including a significant drop in international gas prices, insufficient global economic growth momentum, increased use of alternative energy sources, and warmer-than-usual winter temperatures. European consumption experienced negative growth for the second consecutive year, with total consumption reaching 463.4 billion cubic meters, a decrease of 6.9% year-on-year. This was primarily due to the continued contraction of the manufacturing sector, a decline in overall electricity consumption, and an increase in wind, solar, hydro, and nuclear power generation.

[0003] Plastic, as one of the most versatile materials, is indispensable and widely used in packaging, biomedical devices, the automotive, and electronics industries. Scientists estimate that there are currently 150 million tons of plastic in the ocean, and this figure is increasing at a rate of 10 million tons per year. In less than 10 years, scientists predict that there will be 250 million tons of plastic in the ocean, which will have a devastating impact on marine life. Furthermore, many additives are needed in the plastic synthesis process to meet usage requirements. Most of these additives are toxic, causing soil compaction, damaging soil structure, leading to biological pollution of the soil, and harming the soil ecosystem. Plastic waste is a resource between biomass and fossil fuels, and upgrading and recycling processes hold promise for the resource utilization of waste plastics.

[0004] To address the current issues of complex product composition and cumbersome processing in the chemical upgrading and recycling of polyester plastics, a simple and efficient reaction system needs to be developed. Summary of the Invention

[0005] According to one aspect of this application, a method for preparing natural gas using plastic as a raw material is provided, comprising the following steps:

[0006] Plastics are mixed with a catalyst and reacted in a closed container under a solvent-free atmosphere with a reducing gas atmosphere to obtain a product containing natural gas.

[0007] The plastic is polycarbonate;

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

[0009] The Raney-type catalyst is selected from at least one of Raney Ni, Raney Ni-Mo, Raney Cu, Raney Fe, Raney Ni-Co, Raney Ni-Fe, Raney Ni-Cu, Raney Ni-Al, and Raney Ni-Sn.

[0010] The mass of the catalyst is 10 to 200 wt% of the mass of the plastic;

[0011] Optionally, the mass of the catalyst is 30 to 150 wt% of the mass of the plastic.

[0012] The mass of the catalyst is 10 to 200 wt% of the mass of polycarbonate in the plastic;

[0013] Optionally, the mass of the catalyst is 30 to 150 wt% of the mass of polycarbonate in the plastic.

[0014] The reducing gas atmosphere is a hydrogen atmosphere;

[0015] The pressure of the reducing gas atmosphere is 0.1–5 MPa;

[0016] Optionally, the pressure of the reducing gas atmosphere is 1–5 MPa;

[0017] Optionally, the pressure of the reducing gas atmosphere is 2 to 4 MPa.

[0018] The reaction temperature is 200–350°C;

[0019] Optionally, the reaction temperature is 200–330°C;

[0020] Optionally, the reaction temperature is 280–310°C.

[0021] The reaction time is 0.5–12 hours;

[0022] Optionally, the reaction time is 0.5 to 8 hours;

[0023] Optionally, the reaction time is 2 to 5 hours.

[0024] The sealed container is a sealed pressure vessel.

[0025] This invention provides a method for producing natural gas from polycarbonate plastics, directly converting catalytic plastics into natural gas. This process is environmentally friendly, simple, easy to operate, and highly efficient, yielding high-purity natural gas. It represents a revolutionary technology for producing natural gas from polycarbonate under mild conditions, and has significant strategic importance for adjusting my country's energy structure, promoting energy conservation and emission reduction, and addressing climate change.

[0026] The beneficial effects that this application can produce include:

[0027] 1) This invention realizes the efficient and clean utilization of polycarbonate, and the natural gas produced can be used for urban natural gas pipeline transportation, which has great economic value.

[0028] 2) This invention reduces the temperature and pressure of the reaction, allowing the reaction to proceed under mild conditions, thereby reducing energy consumption and improving thermal efficiency.

[0029] 3) The method of the present invention has simple operation steps, short process and low pollution.

[0030] 4) Using the above steps and methods, polycarbonate can be directly catalytically converted into natural gas under mild conditions, with a carbon yield of up to 70.2%. This method can both upgrade and recycle waste plastics and alleviate the demand pressure on natural gas, which is of great significance for alleviating the contradiction between natural gas supply and demand in my country. Detailed Implementation

[0031] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0032] The Raney-type catalysts in this application embodiment—Raney Ni, Raney Ni-Mo, Raney Cu, Raney Ni-Co, Raney Ni-Fe, Raney Ni-Cu, Raney Ni-Al, and Raney Ni-Sn—are obtained by activating their alloy powders. An appropriate amount of alloy powder is added to a 20wt% sodium hydroxide solution and kept in an oil bath for 1 hour. After the reaction is complete, the mixture is washed with water until neutral to obtain the corresponding Raney-type catalyst, which is then used in the catalytic reaction.

[0033] The carbon yield calculation in this embodiment is as follows:

[0034]

[0035] Example 1

[0036] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with 1 MPa of H2. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0037] The natural gas yield was found to be 5.5%, and the gas distribution was: CH4 (94.9%), C2-C4 (0.6%), and CO2 (4.7%).

[0038] Example 2

[0039] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 2 MPa. Heat to 310 °C using electric heating under magnetic stirring at 800 rpm for 180 min. After the reaction, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0040] The natural gas yield was found to be 40.0%, and the gas distribution was: CH4 (90.2%), C2-C4 (3.2%), and CO2 (6.2%).

[0041] Example 3

[0042] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0043] The natural gas yield was found to be 70.2%, and the gas distribution was: CH4 (86.4%), C2-C4 (2.6%), and CO2 (11.0%).

[0044] Example 4

[0045] Weigh 0.5 g of Raney Ni-Mo catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0046] The natural gas yield was found to be 19.3%, and the gas distribution was: CH4 (97.2%), C2-C4 (2.8%), and CO2 (0%).

[0047] Example 5

[0048] Weigh 0.5 g of Raney Ni-Fe catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating under magnetic stirring at 800 rpm for 180 min. After the reaction, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gas using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0049] The natural gas yield was found to be 6.8%, and the gas distribution was: CH4 (98.8%), C2-C4 (1.2%), and CO2 (0%).

[0050] Example 6

[0051] Weigh 0.5 g of Raney Ni-Cu catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0052] The natural gas yield was found to be 9.2%, and the gas distribution was: CH4 (97.3%), C2-C4 (2.8%), and CO2 (0%).

[0053] Example 7

[0054] Weigh 0.5 g of Raney Ni-Sn catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gas using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0055] The natural gas yield was found to be 6.3%, and the gas distribution was: CH4 (89.4%), C2-C4 (1.1%), and CO2 (9.5%).

[0056] Example 8

[0057] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 280 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0058] The natural gas yield was found to be 57.0%, and the gas distribution was: CH4 (90.0%), C2-C4 (3.6%), and CO2 (6.3%).

[0059] Example 9

[0060] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 300 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0061] The natural gas yield was found to be 66.1%, with the gas distribution as follows: CH4 (87.7%), C2-C4 (3.1%), and CO2 (9.1%).

[0062] Example 10

[0063] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 300 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0064] The natural gas yield was found to be 67.0%, and the gas distribution was: CH4 (91.2%), C2-C4 (2.9%), and CO2 (9.1%).

[0065] Example 11

[0066] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 4 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0067] The natural gas yield was found to be 38.0%, and the gas distribution was: CH4 (97.8%), C2-C4 (2.2%), and CO2 (0%).

[0068] Example 12

[0069] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 120 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0070] The natural gas yield was found to be 21.6%, and the gas distribution was: CH4 (97.2%), C2-C4 (2.8%), and CO2 (0%).

[0071] Example 13

[0072] Weigh 0.2 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0073] The natural gas yield was found to be 5.0%, and the gas distribution was: CH4 (98.4%), C2-C4 (1.1%), and CO2 (0.5%).

[0074] Example 14

[0075] Weigh 1.5g of Raney Ni catalyst and add it to a 50mL reactor, along with 1.0g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3MPa. Heat to 290℃ using electric heating while stirring magnetically at 800rpm, and react for 180min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0076] The natural gas yield was found to be 23%, and the gas distribution was: CH4 (97.5%), C2-C4 (2.4%), and CO2 (0%).

[0077] Example 15

[0078] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 800 rpm, and react for 60 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0079] The natural gas yield was found to be 19.9%, and the gas distribution was: CH4 (97.6%), C2-C4 (2.4%), and CO2 (0%).

[0080] Example 16

[0081] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 400 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0082] The natural gas yield was found to be 51.9%, and the gas distribution was: CH4 (91.0%), C2-C4 (4.2%), and CO2 (4.8%).

[0083] Example 17

[0084] Weigh 0.5 g of Raney Ni catalyst and add it to a 50 mL reactor, along with 1.0 g of polycarbonate granules. Seal the reactor, purge with N2 3-5 times to expel air, then purge with H2 3-5 times to expel N2, and finally purge with H2 at 3 MPa. Heat to 290 °C using electric heating while stirring magnetically at 600 rpm, and react for 180 min. After the reaction is complete, stop stirring and cool the reactor to room temperature in an ice-water bath. Record the reaction termination temperature and pressure. Open the gas outlet and collect the generated gases using a gas bag for gas phase analysis. Add water to the reactor, remove the catalyst after reaction, centrifuge it, and recycle it.

[0085] The natural gas yield was found to be 64.1%, and the gas distribution was: CH4 (90.1%), C2-C4 (3.6%), and CO2 (6.3%).

[0086] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing natural gas using plastic as a raw material, characterized in that, Includes the following steps: Plastics are mixed with a catalyst and reacted in a closed container under a solvent-free atmosphere with a reducing gas atmosphere to obtain a product containing natural gas. The plastic is polycarbonate; The catalyst is a Raney-type catalyst.

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

3. The preparation method according to claim 1, characterized in that, The mass of the catalyst is 10-200 wt% of the mass of the polycarbonate; Preferably, the mass of the catalyst is 30 to 150 wt% of the mass of the polycarbonate.

4. The preparation method according to claim 1, characterized in that, The reducing gas atmosphere is a hydrogen atmosphere; The pressure of the reducing gas atmosphere is 0.1–5 MPa; Preferably, the pressure of the reducing gas atmosphere is 1–5 MPa; Preferably, the pressure of the reducing gas atmosphere is 2 to 4 MPa.

5. The preparation method according to claim 1, characterized in that, The reaction temperature is 200–350°C; Preferably, the reaction temperature is 200–330°C; Preferably, the reaction temperature is 280–310°C.

6. The preparation method according to claim 1, characterized in that, The reaction time is 0.5–12 hours; Preferably, the reaction time is 0.5 to 8 hours; Preferably, the reaction time is 2 to 5 hours.

7. The preparation method according to claim 1, characterized in that, The sealed container is a sealed pressure vessel.

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