Process for co-producing oil products and carbon materials from lignin and waste plastics

Abstract

The invention discloses a process for co-producing oil products and carbon materials from lignin and waste plastics, and belongs to the technical field of comprehensive utilization of resources and energy chemical industry. The method comprises the following steps: crushing, screening and drying lignin and waste plastics, gradually heating the fully mixed raw materials to a first temperature in an inert atmosphere, keeping the temperature for a period of time, carrying out pyrolysis, collecting an oil product at the lower end of a reactor after the pyrolysis reaction is finished, and taking out a carbon material from the reactor; fully mixing the carbon material with an activating agent, heating to a second temperature in an inert atmosphere, and keeping the second temperature for a period of time, so that the carbon material is subjected to pore forming and activation; performing acid pickling, water washing and drying on the pore-formed and activated carbon material to obtain the carbon material with high specific surface area; the second temperature is higher than the first temperature. The method has the advantages of low requirements on raw materials, simplicity and convenience in operation, high utilization rate of the whole product, capability of effectively improving the value of the product and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of resources and energy chemical industry, and specifically relates to a process for co-producing oil products and carbon materials from lignin and waste plastics. Background Art

[0002] Due to society's dependence on fossil fuels and concerns about environmental issues (global warming, carbon emissions, etc.), the use of renewable resources and waste as energy is increasing. In addition, since the 21st century, economic growth, urbanization and industrialization have led to the generation of a large amount of waste plastics, which in turn has had a great negative impact on human health and the entire ecosystem. Biomass and waste plastics account for about 10-20% of the world's total primary energy supply. This is a renewable energy source that cannot be ignored and is expected to become an important part of reducing CO2 emissions. As a result, there is an urgent need to develop new technologies to improve the conversion efficiency of these raw materials into energy products, bulk chemicals and high value-added materials.

[0003] Among the many conversion technologies, pyrolysis is a promising technology for converting biomass and waste into high-value products. The products after pyrolysis are divided into three types: pyrolysis oil, carbon and gas phase products. Among them, pyrolysis oil can be used alone or mixed with petroleum-based fuels and integrated into existing fuel transportation and infrastructure. Patent CN105121605 discloses a method for pyrolyzing waste plastics through molecular sieve catalysis and obtaining aromatic products through hydrogenation. Patent CN105733625 discloses a method for pyrolyzing and upgrading lignin in a two-stage reaction system to obtain aromatic products. Existing technologies often require the use of expensive molecular sieve catalysts, complex processes, and residual substances are often not fully utilized. In particular, the carbon produced during the pyrolysis process is often discarded, which is a huge waste of carbon resources. Therefore, how to improve the carbon atom utilization rate of raw materials is crucial. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a process for the co-production of oil products and carbon materials from lignin and waste plastics. By adding waste plastics to waste biomass raw materials and utilizing the synergistic effect between the two substances, on the one hand, the oil products are regulated by different reaction processes to improve their quality, and on the other hand, the formation of carbon is increased to obtain carbon materials with a high specific surface area, thereby reducing the formation of gas phase products and increasing the carbon atom utilization rate of the raw materials. Among them, the carbon material with a high specific surface area is a widely used material, which can be used as a negative electrode material for power supply, a catalyst, an adsorption and filtration material, etc. Using waste biomass and waste plastics as raw materials, it is possible to prepare fuel oil and carbon materials with a simple and low-cost technology, and also complete the environmental protection measure of recycling resources.

[0005] The technical solution provided by the present invention is as follows:

[0006] A process for co-producing oil products and carbon materials from lignin and waste plastics, comprising the following steps: crushing, screening and drying lignin and waste plastics, gradually heating the fully mixed raw materials to a first temperature under an inert atmosphere and keeping them for a period of time for pyrolysis, collecting oil products at the lower end of a reactor after the pyrolysis reaction is completed, and taking out the carbon material from the reactor; fully mixing the carbon material with an activator, heating them to a second temperature under an inert atmosphere and keeping them for a period of time to activate the carbon material to form pores; acid-washing, water-washing and drying the activated and pore-forming carbon material to obtain a carbon material with a high specific surface area; the second temperature is higher than the first temperature.

[0007] Furthermore, the first temperature is 400~600°C, the holding time of the first temperature is 0.1~4 h, and the speed of rising to the first temperature is 0.5~20°C / min; the second temperature is 700~900°C, the holding time of the second temperature is 0.1~4 h, and the speed of rising to the second temperature is 0.5~20°C / min.

[0008] Furthermore, the lignin is one or more of alkaline lignin, kraft lignin, and dealkalized lignin, and the waste plastics are one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate; and the mass ratio of lignin to waste plastics is 1~9:1~9.

[0009] Furthermore, the activator is one or more of ZnCl2, H3PO4, Na2CO3, NaHCO3, NaOH, K2CO3, KHCO3, and KOH.

[0010] Furthermore, the mass ratio of the carbon material to the activator is 1:1~4.

[0011] Furthermore, the inert atmosphere is one of high-purity nitrogen, high-purity argon, and high-purity helium.

[0012] Furthermore, the carbon material and the activator are mixed by one or more of dry material ball milling, dry material roller mixing, and stirring wet mixing.

[0013] Further, the lignin and waste plastics are crushed, sieved and dried, wherein the drying temperature is 60-120° C. and the drying time is 12-48 h.

[0014] Furthermore, the activated pore-forming carbon material is acid-washed, water-washed and dried at a drying temperature of 80 to 160° C. for a drying time of 12 to 24 h.

[0015] The present invention also provides a high specific surface area carbon material, which is prepared by the above method.

[0016] The present invention provides a method for preparing porous carbon from discarded organic solid waste, the method comprising the following contents:

[0017] (1) Crush, screen and dry various raw materials;

[0018] (2) mixing two or more different types of materials processed in step 1 according to a certain proportion;

[0019] (3) placing the material obtained in step (2) above in a constant temperature zone of a pyrolysis reactor, heating the material to 400-600°C at a heating rate of 0.5-20°C / min under an inert atmosphere and maintaining the temperature for 1-240 min to promote full pyrolysis of the material. After the reaction is completed, the oil product is collected at the lower end of the reactor and taken out of the carbon material reactor;

[0020] (4) further activating the carbon material in step (3) to form pores;

[0021] The activation pore-forming method is any one of the following:

[0022] 1) The pre-carbonized material is activated to form pores at a temperature of 700-900°C in an inert environment;

[0023] 2) Mix the pre-carbonized material with the activator in an inert environment at a temperature of 700-900°C to activate and form pores;

[0024] (5) acid-washing, water-washing and drying the carbon material obtained in the above step (4) to finally obtain a porous carbon material;

[0025] In step (1) of the present invention, the particle size of the raw material screening is 80-200 mesh;

[0026] In step (1) of the present invention, the drying temperature is 60-120° C. and the drying time is 12-48 h;

[0027] In step (1) of the present invention, the raw materials are one or more of lignin and plastics, wherein the lignin is one or more of alkaline lignin, kraft lignin, and dealkalized lignin, and the waste plastics are one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate;

[0028] Furthermore, in step (2) of the present invention, the mass ratio of lignin to waste plastic is 1:9 to 9:1;

[0029] The mixing method in step (3) of the present invention is stirring wet mixing, dry material ball milling mixing, dry material roller mixing, preferably dry material roller mixing;

[0030] Furthermore, in step (4) of the present invention, the mixing time is 0.5 to 8 h;

[0031] The inert atmosphere in step (3) of the present invention is one of high-purity nitrogen, high-purity argon, and high-purity helium;

[0032] The heating rate for further heating in step (4) of the present invention is 10°C / min;

[0033] The activation time in step (4) of the present invention is 0.5 to 4 h.

[0034] The mixing method with the activator in step (4) of the present invention is one or more of dry material ball milling, dry material roller mixing, and stirring wet mixing, wherein the solvent for wet mixing is an aqueous solution, and the preferred mixing method is stirring wet mixing;

[0035] Further, the activator is one or more of ZnCl2, H3PO4, Na2CO3, NaHCO3, NaOH, K2CO3, KHCO3, KOH, preferably KOH;

[0036] Furthermore, the mass ratio of the carbonized material to the activator is 1:1 to 1:4.

[0037] Further, the mixing time is 0.5 to 8 h, preferably 6 h;

[0038] The acid used in the pickling in step (5) of the present invention is one or more of sulfuric acid, nitric acid and hydrochloric acid, preferably hydrochloric acid;

[0039] Furthermore, the water washing in step (5) of the present invention specifically comprises the steps of repeatedly washing with deionized water until the deionized water after washing is neutral;

[0040] Furthermore, in step (5) of the present invention, the drying temperature is 80-160° C. and the drying time is 12-24 h.

[0041] Beneficial Effects

[0042] In the present method, in a pyrolysis reactor, under the protection of an inert gas, lignin and waste plastics are co-pyrolyzed at high temperature, and by regulating different raw material ratios and pyrolysis reaction processes to strengthen the synergistic effect between molecules at high temperature, a biocarbon material is co-produced while producing a product rich in aromatic oil phase. Furthermore, the biocarbon is activated to obtain a carbon material with a high specific surface area and a wide range of application prospects. The preparation method comprises the following steps: fully mixing the dried raw materials in a specific ratio, under the protection of an inert atmosphere, the pyrolysis temperature is 400-600°C, the pyrolysis reaction time is 1-240 min, the pyrolysis heating rate is 0.5-20°C / min, the oil products and biocarbon after the reaction are collected respectively, and the collected carbon is activated to form pores to form a carbon material with a high specific surface area. The method has the advantages of low raw material requirements, simple operation, high overall product utilization, and effective improvement of the value of the product.

[0043] The present invention uses biomass resources and waste plastics as raw materials, takes the synergistic effect between biomass and plastics in the pyrolysis process as the core, and through simple pyrolysis process and activation process, can selectively adjust the quality of pyrolysis oil and obtain high specific surface area porous carbon materials. Compared with traditional solid waste treatment processes and methods, the present invention has the advantages of low cost, convenient operation, and stable co-production of high-quality bio-oil and activated carbon. The main components of bio-oil are aromatic compounds, and are concentrated in C6~C16. This type of product can be used as a gasoline additive and is also an important component of fuel. High specific surface area carbon material is also an important high-value material, which can be used as pollutant adsorption and treatment materials, catalysts, and electrode materials in energy storage devices. In addition, the present invention converts waste into high-value-added products, has significant environmentally friendly advantages, is more conducive to reducing pollution emissions and enhancing resource utilization, and is expected to become a process technology for achieving energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The proportions of various compounds in the oil in Example and Comparative Examples 1 and 2;

[0045] Figure 2 is the proportion of compounds with different carbon numbers in the oil in Example and Comparative Examples 1 and 2;

[0046] Figure 3 This is the nitrogen physical adsorption-desorption curve of the carbon material in Example 3. DETAILED DESCRIPTION

[0047] Example 1

[0048] Step 1: PET (polyethylene terephthalate) and alkaline lignin (AL) are crushed separately, and then sieved to obtain particles with a size of 80-100 mesh, and the particles are placed in an oven at 80°C for drying for 24 hours;

[0049] Step 2: Weigh 5 g of treated lignin and 5 g of PET and mix them with a roller mixer. During the mixing, a certain amount of spherical zirconium oxide beads are added to ensure sufficient tumbling mixing of the raw materials;

[0050] Step 3: Place the mixed raw materials in the constant temperature zone of the pyrolysis reactor, introduce high-purity nitrogen at a flow rate of 50 mL / min, increase the temperature from room temperature to 600°C at a heating rate of 2°C / min, and stay at 600°C for 2 h for pyrolysis reaction. After the reaction is completed, collect the oil product at the end of the pyrolysis reactor;

[0051] Step 4: The carbon material obtained in step 3 is mixed with the activator. The specific steps are as follows: the carbon material and potassium hydroxide are weighed separately according to a mass ratio of 1:3. First, the potassium hydroxide is dissolved in distilled water, and the carbon material is placed in the potassium hydroxide aqueous solution and mixed and stirred for 6 hours. Then, it is heated at 80°C to evaporate the water. After the water is evaporated, it is transferred to a 105°C oven for further drying and dehydration for 24 hours. The dehydrated mixture is placed in a tubular furnace, and the temperature is increased to 850°C at a heating rate of 10°C / min and retained for 2 hours, and then naturally cooled to room temperature.

[0052] Step 5: The carbon material obtained in step 4 is acid-washed with 2 M hydrochloric acid, filtered, and then washed with distilled water until neutral, and then placed in an oven at 105° C. to dry, thereby obtaining a porous carbon material.

[0053] In this example, 32.7 wt% of oil products were obtained (based on the initial weight of the raw materials), of which the aromatic hydrocarbon products accounted for 28.8%, the yield of carbon materials was 36.0 wt%, the specific surface area of ​​the activated pore-forming carbon materials was 2,665.7 m² / g, and the micro-mesopore volume was 3.95 cm 3 ·g -1 , mesopores account for 73.7% of micromesopores.

[0054] In the co-pyrolysis of lignin and waste plastics, this embodiment achieved the best oil product yield, Figure 2 The carbon number distribution diagram of the oil products is basically concentrated in C6~C16, which meets the standards of gasoline and fuel additives. This shows that the co-pyrolysis of lignin and PET can improve the quality of pyrolysis oil. The yield of carbon materials reaches the highest. During the co-pyrolysis process, the primary pyrolysis products of PET and the primary pyrolysis products of lignin, phenolic substances, are condensed and cross-linked again, which promotes the formation of carbon.

[0055] Example 2

[0056] The same method as in Example 1 was used except that the mass of lignin and PET in step 2 of Example 1 was 3 g:7 g.

[0057] In this example, 33.9 wt% of oil products were obtained (based on the initial weight of the carbon precursor), of which the aromatic hydrocarbon products accounted for 19.4%, the yield of carbon material was 28.6 wt%, the specific surface area of ​​the activated pore-forming carbon material was 2,857.7 m² / g, and the micro-mesopore volume was 2.22 cm 3 ·g -1 , mesopores account for 40.6% of micromesopores.

[0058] In this embodiment, the carbon material with the highest specific surface area is obtained. Since the raw material lignin contains alkaline substances, when the lignin ratio is relatively high, the alkaline substances increase accordingly, which to a certain extent causes excessive activation of the carbon material and causes a reduction in specific surface area. On the contrary, the carbon material formed by less lignin in the raw material will be more conducive to subsequent activation and pore formation to obtain a high specific surface area.

[0059] Example 3

[0060] The same method as in Example 1 was used except that the mass of lignin and PET in step 2 of Example 1 was replaced with 7 g:3 g.

[0061] In this example, 29.8 wt% of oil products were obtained (based on the initial weight of the carbon precursor), of which the aromatic hydrocarbon products accounted for 49.9%, the yield of carbon material was 31.8 wt%, the specific surface area of ​​the activated pore-forming carbon material was 2,248.7 m² / g, and the micro-mesopore volume was 2.54 cm 3 ·g -1 , mesopores account for 64.57% of micromesopores.

[0062] Figure 3 is the nitrogen physical adsorption-desorption curve of the carbon material obtained in Example 3. The large amount of nitrogen adsorption at low pressure indicates the existence of microporous structure, and the appearance of hysteresis loop indicates that the surface of the carbon material has a mesoporous structure. Although the oil product is reduced compared with Examples 1 and 2, its aromatic product is significantly increased, such as Figure 1 This is more beneficial for oil products to be used as additives for gasoline and fuel.

[0063] Comparative Example 1

[0064] The same method as in Example 1 was used for preparation except that the raw material in step 2 in Example 1 was replaced by lignin.

[0065] This comparative example obtained 37.4 wt% of oil products (based on the initial weight of the carbon precursor), of which aromatic hydrocarbon products accounted for 18.7%, the yield of carbon material was 30.5 wt%, and the specific surface area of ​​the carbon material after activation and pore formation was 0.

[0066] Lignin is a pyrolysis raw material, and the yield of oil products is higher than the oil products generated by co-pyrolysis with PET, but its products are mainly composed of phenolic substances. If used as an additive for gasoline or fuel oil, too much phenolic substances will reduce the quality of the oil. The yield of carbon material is also lower than that of Examples 1 and 3, and its own excessive alkaline substances will cause subsequent activation pore formation to become difficult or even consume a large amount of carbon. These problems can be solved by co-pyrolysis of lignin and PET.

[0067] Comparative Example 2

[0068] The same method as in Example 1 was used for preparation except that the raw material in step 2 in Example 1 was replaced by PET.

[0069] In this comparative example, 40.0 wt% of oil products (based on the initial weight of the carbon precursor) were obtained, of which the aromatic hydrocarbon products accounted for 14.8 wt%, the yield of carbon material was 15.1 wt%, the specific surface area of ​​the activated pore-forming carbon material was 3263.6 m² / g, and the micro-mesopore volume was 1.70 cm 3 ·g -1 , mesopores account for 16.3% of micromesopores.

[0070] When PET is used as the pyrolysis raw material, the oil product contains a large amount of acidic substances, such as Figure 1 As shown. Carboxylic acid is often not desirable during pyrolysis because it can seriously corrode pipelines and equipment. In addition, although the activated pore-forming carbon material has a very high specific surface area, its carbon material yield is extremely low. In the process of co-pyrolysis of lignin and PET, the acidic substances are significantly reduced, such as Figure 1 More importantly, the yield of aromatic products was significantly improved. The yield of carbon materials was also significantly increased during the co-pyrolysis of lignin and PET, with the maximum increase of nearly 20 wt%.

[0071] Comparative Example 3

[0072] The same method as in Example 1 was used except that the amount of the activator used in step 4 of Example 2 was 0.

[0073] This comparative example obtained 32.7 wt% of oil products (based on the initial weight of the feedstock), of which aromatic hydrocarbon products accounted for 28.8%, the yield of carbon material was 36.0 wt%, and the specific surface area was 550.20 m 2 ·g -1 , the micro-mesopore volume is 0.46cm 3 ·g -1 , mesopores account for 54.3% of micromesopores.

[0074] Compared with the embodiment using an activator, the specific surface area of ​​the carbon material in this comparative example is lower. This is because there is a certain threshold for the activation and pore formation of carbon by relying solely on the high temperature of the second temperature. The use of an activator plays an important role in increasing the specific surface area of ​​the carbon material. From the embodiment of this patent, if the specific surface area of ​​the carbon material is to reach 2000 m 2 ·g -1 Above, the use of activator is essential.

[0075] The present invention utilizes the synergistic effect of the pyrolysis process of the two substances by co-pyrolyzing lignin and waste plastics. On the one hand, different reaction processes are used to regulate the oil products to improve their quality, increase the aromatic content, and control the carbon tree of the oil products between C6 and C16. On the other hand, the synergistic effect between the co-pyrolysis primary products further leads to condensation and cross-linking, promotes the formation of carbon and obtains carbon materials with high specific surface area, thereby improving the carbon atom utilization rate of the raw materials. Comprehensively considering the oil products and more high-yield carbon materials with high specific surface area, when the ratio of lignin to PET is 5:5, the heating rate is 2℃ / min, the first pyrolysis temperature is 600℃, the pyrolysis time is 2 h, the second temperature activation pore-forming temperature is 850℃, and the ratio of activator to carbon material is 3:1, 32.7 wt% of oil products can be obtained, of which the aromatic hydrocarbon products account for 28.8%, the yield of carbon materials is 36.0 wt%, and the specific surface area of ​​the carbon material after activation and pore-forming is 2,665.7 m² / g. If you want to further improve the quality of oil products, when the ratio of lignin to PET is 7:3, the heating rate is 2℃ / min, the first pyrolysis temperature is 600℃, the pyrolysis time is 120min, the second temperature activation pore-forming temperature is 850℃, and the ratio of activator to carbon material is 3:1, the highest quality oil product with a yield of 29.8 wt% is obtained, of which the aromatic hydrocarbon product accounts for 49.9%, the yield of carbon material is 31.8 wt%, and the specific surface area of ​​the carbon material after activation and pore-forming is 2,248.7 m² / g.

Claims

1. A process for co-producing oil products and carbon materials from lignin and waste plastics, characterized in that: The method comprises the following steps: crushing, screening and drying lignin and waste plastics, gradually heating the fully mixed raw materials to a first temperature under an inert atmosphere and maintaining the temperature for a period of time for pyrolysis, collecting oil products at the lower end of the reactor after the pyrolysis reaction, and taking out the carbon material from the reactor; fully mixing the carbon material with an activator, heating the temperature to a second temperature under an inert atmosphere and maintaining the temperature for a period of time to activate the carbon material to form pores; acid-washing, water-washing and drying the activated and pore-forming carbon material to obtain a carbon material with a high specific surface area; the second temperature is higher than the first temperature.

2. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The first temperature is 400~600℃, the holding time of the first temperature is 0.1~4 h, and the speed of rising to the first temperature is 0.5~20℃ / min; the second temperature is 700~900℃, the holding time of the second temperature is 0.1~4h, and the speed of rising to the second temperature is 0.5~20℃ / min.

3. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The lignin is one or more of alkaline lignin, kraft lignin, and dealkalized lignin; the waste plastics are one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate; and the mass ratio of lignin to waste plastics is 1-9:1-9.

4. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The activator is one or more of ZnCl2, H3PO4, Na2CO3, NaHCO3, NaOH, K2CO3, KHCO3, and KOH.

5. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The mass ratio of carbon material to activator is 1:1~4.

6. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The inert atmosphere is one of high-purity nitrogen, high-purity argon and high-purity helium.

7. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The carbon material and the activator are mixed by one or more of dry material ball milling, dry material roller mixing, and stirring wet mixing.

8. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The lignin and waste plastics are crushed, sieved and dried, wherein the drying temperature is 60-120° C. and the drying time is 12-48 hours.

9. The process for co-producing oil products and carbon materials from lignin and waste plastics according to claim 1, characterized in that: The pore-forming and activated carbon material is acid-washed, water-washed and dried at a drying temperature of 80-160°C and a drying time of 12-24 h.

10. A high specific surface area carbon material, characterized in that: Prepared by the method according to any one of claims 1 to 9.

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