Method for producing fuel oil through pyrolysis of fuel oil and photo-thermal concerted catalysis plastic

Abstract

The invention provides a method for producing fuel oil through pyrolysis of fuel oil and photo-thermal concerted catalysis plastics. The method comprises the following steps: (1) pyrolyzing plastic to obtain pyrolysis steam; (2) carrying out catalytic reaction on the pyrolysis steam in the presence of a catalyst under illumination to obtain a mixed product; and (3) condensing the mixed product to obtain the fuel oil. According to the method, the high-quality fuel oil is prepared by taking plastic or waste plastic as a raw material, the problem of increasing shortage of fossil fuel is relieved while environmental pollution is reduced, and meanwhile, the selectivity of gasoline and aviation oil in pyrolytic oil is effectively improved, so that the quality of the oil is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling and resource utilization, and in particular to a method for producing fuel oil by catalyzing the pyrolysis of plastics through the coordinated catalysis of fuel oil and light and heat. Background Art

[0002] With the rapid development of my country's economy, plastic products have been widely used in daily life, industrial production and other fields. However, the amount of waste generated by plastic products during use has increased year by year, bringing serious burden to the environment. According to statistics, my country generates about 80 million tons of plastic waste each year, and the effective recycling rate is less than 50%. Due to improper disposal of waste plastics, a large amount of plastic waste is treated by landfill, incineration and other methods, which not only occupies a large amount of land resources, but also produces harmful gases and pollutants, seriously threatening the ecological environment and human health. Therefore, converting waste plastics into high-value-added chemicals not only realizes the efficient recycling of waste plastics, but also is an effective way to control white pollution. Traditional pyrolysis treatment methods often require high temperatures (>500℃), which leads to huge energy input and dissipation, reduces economic efficiency, and the added value of the obtained chemicals is low. Therefore, it is of great research value to find energy-saving and environmentally friendly plastic treatment methods and increase the added value of chemicals. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the prior art at least to a certain extent. To this end, one object of the present invention is to provide a method for producing fuel oil by catalyzing the pyrolysis of plastics by synergistic catalysis of fuel oil and light and heat.

[0004] In one aspect of the present invention, the present invention provides a method for producing fuel oil by photothermal catalytic pyrolysis of plastic. Figure 1 , the method comprising: (1) Pyrolyzing the plastic to obtain pyrolysis vapor; (2) subjecting the pyrolysis vapor to a catalytic reaction under a catalyst and light to obtain a mixed product; (3) Condensing the mixed product to obtain fuel oil.

[0005] According to the method of the above embodiment of the present invention, the plastic is first pyrolyzed to obtain pyrolysis vapor, and then the pyrolysis vapor is catalytically reacted under a catalyst and light to obtain a mixed product. The above two stages are used to sequentially perform heat treatment and photocatalytic treatment on the plastic, that is, the photothermal synergistic catalytic pyrolysis of the plastic can directly convert light energy into heat energy, achieve efficient pyrolysis of the plastic, and reduce energy consumption. At the same time, due to the joint contribution of photochemistry and thermochemistry, the high-energy photons generated in the reaction can promote the activation of inert plastic molecules and produce active free radicals and fragments, thereby significantly improving the gasoline range and aviation fuel range selectivity of the refined oil, and greatly improving the quality of the fuel. Finally, the mixed product is condensed, the condensable part is condensed and collected as fuel, and the non-condensable part is collected as combustible gas.

[0006] It should be noted that plastics include but are not limited to waste plastics. Pyrolysis can be performed by placing plastics in a pyrolysis furnace for pyrolysis. At the same time, the present application does not specifically limit the source of light used for illumination, such as sunlight, which includes ultraviolet light, visible light and near-infrared light. Sunlight can be a natural sunlight source or simulated sunlight (including but not limited to xenon lamps).

[0007] In some embodiments of the present invention, in step (1), the pyrolysis temperature is 375°C to 550°C. For example, the pyrolysis temperature is 375°C, 380°C, 400°C, 420°C, 450°C, 470°C, 500°C, 550°C, etc., or a range between any two of the above values. The inventors have found that different temperatures have a significant impact on the formation of products. At lower temperatures, liquid products (such as oils) and solid products (such as charcoal) are more likely to be formed. At lower pyrolysis temperatures, polymer chains will break to form larger hydrocarbons, while at higher pyrolysis temperatures, the generated products will tend to be gaseous compounds, such as H2, CH4, C2H4, etc., and the liquid products will be reduced. Controlling the pyrolysis temperature within the above range facilitates the acquisition of pyrolysis vapor that is conducive to subsequent reactions.

[0008] In some embodiments of the present invention, in step (1), the plastic includes at least one of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride, and polyethylene terephthalate, preferably polypropylene.

[0009] In some embodiments of the present invention, in step (1), the particle size of the plastic is 1 mm to 100 mm. By controlling the particle size of the plastic within the above range, the plastic can be pyrolyzed more thoroughly and energy consumption can be reduced. It should be noted that the present application does not specifically limit the shape of the specific plastic particles, such as flake or spherical.

[0010] In some embodiments of the present invention, step (1) further comprises: introducing an inert gas, wherein the inert gas carries the pyrolysis vapor to move. Specifically, the flow rate of the inert gas is not greater than 200 mL / min. The inert gas comprises at least one of argon and helium. By introducing an inert gas into the pyrolysis container, the pyrolysis vapor can be assisted to quickly move to the catalyst stage for catalytic reaction, thereby improving the reaction efficiency.

[0011] In some embodiments of the present invention, in step (2), the catalyst includes a precursor and a support body loaded on the precursor, the precursor includes at least one of a metal oxide, a molecular sieve, and biochar, and the support body includes a semiconductor material. The inventors have found that the use of the above-mentioned type of catalyst can achieve full spectrum absorption, can reduce the pyrolysis reaction temperature, and can effectively improve the selectivity of gasoline and aviation fuel in the pyrolysis oil, thereby significantly improving the quality of the oil. It should be noted that the catalyst of the present application can be recycled and reused, thereby significantly reducing production costs.

[0012] In some embodiments of the present invention, the preparation method of the catalyst comprises an impregnation method or a precipitation method, preferably an impregnation method.

[0013] As an example, the catalyst preparation method is as follows: tetrabutyl titanate and γ-Al2O3 are mixed in anhydrous ethanol, stirred to dryness and then calcined, and then Ni metal particles are loaded to prepare a catalyst having both optical and thermal effects.

[0014] In some embodiments of the present invention, the mass proportion of the support body is 1% to 20% based on the total mass of the catalyst. For example, the mass proportion is 1%, 3%, 5%, 8%, 10%, 13%, 15%, 17%, 20%, etc., or any range between the above two data. The inventors have found that when the mass proportion of the support body is controlled within the above range, the oil yield and the selectivity for the gasoline range and the aviation fuel range can be improved, and high-yield gasoline range and aviation fuel range products can be prepared.

[0015] In some embodiments of the present invention, the semiconductor material includes at least one of Ti, Si, and Ge.

[0016] In some embodiments of the present invention, the support body further comprises a metal, and the metal comprises at least one of nickel, iron, and zinc. The inventors have found that when the support body comprises a metal, the loading of metal particles can achieve rapid heating and local high temperature of the catalyst, improve catalytic efficiency, and reduce energy consumption.

[0017] In some embodiments of the present invention, based on the total mass of the catalyst, the mass proportion of the metal is no more than 15%, for example, the mass proportion is 1%, 2%, 3%, 5%, 7%, 10%, 12%, 15%, etc. The inventors have found that based on the total mass of the catalyst, the mass proportion of the metal is no more than 15%, which can improve the fuel yield and ensure the selectivity of the products in the gasoline range and the aviation fuel range.

[0018] In some embodiments of the present invention, the mass ratio of the plastic to the catalyst is (1-4): (2-1). For example, the mass ratio is 1:2, 2:2, 3:2, 4:2, 2:1, 3:1, 4:1, etc. The inventors found that as the mass of the plastic raw material increases, the oil yield gradually increases, but with the decrease in the quality of the oil product, if the raw material increases to a certain mass, wax will be produced. Therefore, the mass ratio of the plastic to the catalyst in the present application is within the above range, which can improve the quality of the oil and obtain high-yield gasoline and aviation fuel products.

[0019] In some embodiments of the present invention, in step (2), the temperature of the catalytic reaction is 375°C to 550°C, and the time of the catalytic reaction is 15min to 40min. For example, the temperature is 375°C, 380°C, 400°C, 420°C, 450°C, 470°C, 500°C, 550°C, etc., and the time is 15min, 20min, 25min, 30min, 35min, 40min, etc. The inventors found that the catalytic temperature mainly affects the distribution and selectivity of the product. The product after the first stage of pyrolysis will be further cracked and reformed under the action of the catalyst. A lower catalytic temperature will be conducive to the generation of more liquid products. The higher the catalytic temperature, the more the final product will tend to be a gas product. At the same time, carbon deposition will occur, reducing the activity and life of the catalyst. Therefore, the present application controls the temperature and time of the catalytic reaction within the above range to obtain high-yield gasoline and aviation fuel products.

[0020] When it is necessary to explain that the catalytic reaction is maintained within the above temperature range, heating is required. The present application does not specifically limit the specific heating method, such as resistance heating, or xenon lamp heating, etc. Specifically, the catalytic section is provided with energy by two light sources irradiating the catalyst in opposite directions, and the catalytic temperature is changed by changing the intensity of the light source or the distance between the two light sources. The intensity of the light source can be reflected by the output power, and the output power is 250W~500W. The distance adjustment can be achieved by temperature-coupled forward and reverse screw slide control, and the distance between the two lamps is adjusted to 100mm~1000mm. And a thermocouple can be inserted into the center of the catalytic section to measure the temperature.

[0021] In a second aspect of the present invention, a fuel is provided. According to an embodiment of the present invention, the fuel is prepared by the above method. Therefore, the fuel has a high added value.

[0022] In some embodiments of the present invention, the mass proportion of C5-C12 gasoline in the fuel is not less than 70%, and the mass proportion of C8-C12 aviation fuel in the fuel is not less than 76%.

[0023] The present invention has at least the following technical effects: (1) Using plastic or waste plastic as raw materials to produce high-quality fuel reduces environmental pollution while alleviating the increasing shortage of fossil fuels, which is in line with the current "dual carbon" policy.

[0024] (2) By modifying the catalyst and loading semiconductors and / or metal particles, the pyrolysis reaction temperature can be lowered. At the same time, under the action of the modified catalyst, the selectivity for gasoline and aviation fuel in the pyrolysis oil can be effectively improved, thereby significantly improving the quality of the oil.

[0025] (3) The present invention uses sustainable energy light to carry out photothermal synergistic catalytic reaction. Under photothermal conditions, the ultraviolet light part of sunlight can effectively reduce the inertness of plastics, and the modified catalyst can absorb visible light and infrared light parts, converting light energy into heat energy, thereby reducing energy consumption.

[0026] (4) The catalyst after the reaction of the present invention can be recovered to achieve recycling and improve economic efficiency. At the same time, the obtained combustible gas can be used as synthesis gas or civil fuel gas after purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a schematic flow chart of a method for producing fuel oil by photothermal synergistic catalytic pyrolysis of plastics according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] 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. The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0030] Example 1

[0031] (1) 1.5 g of plastic bottles (polypropylene) were crushed into 3 mm particles and placed in a pyrolysis system. The pyrolysis temperature was set to 500 °C, and argon was used as the carrier gas at a flow rate of 50 mL / min.

[0032] (2) Argon gas carries the pyrolysis vapor formed in step (1) into the catalytic section. The mass ratio of plastic to catalyst is 1:1. The distance between the two xenon lamps is adjusted so that the temperature of the catalytic section is constant at 500°C. The reaction is started for 20 minutes to obtain a mixed product. The catalyst is NiTiAl catalyst, and the specific preparation process is as follows: 15g of tetrabutyl titanate (Macklin) and 15g of γ-Al2O3 are mixed and added to anhydrous ethanol, stirred evenly until dry, left to stand overnight, calcined at 650℃ for 5h, with a heating rate of 10℃ / min, to obtain a TiAl precursor, in which the Ti loading amount in the TiAl precursor is 10wt%. Ni(NO3)2·6H2O (making the Ni loading amount 10wt%) is added, stirred evenly with the TiAl precursor in anhydrous ethanol until dry, left to stand overnight, calcined at 650℃ for 2h, with a heating rate of 10℃ / min, and passed through a 20-40 mesh sieve to obtain a NiTiAl catalyst.

[0033] (3) The condensable portion of the mixed product obtained in step (2) is condensed and collected as pyrolysis oil, and the non-condensable portion is collected as combustible gas.

[0034] Example 2

[0035] The difference between Example 2 and Example 1 is that in step (1), a 3 g plastic bottle (polypropylene) is used, that is, the mass ratio of plastic to catalyst is 2:1.

[0036] Example 3

[0037] The difference between Example 3 and Example 1 is that in step (1), a 4.5 g plastic bottle (polypropylene) is used, that is, the mass ratio of plastic to catalyst is 3:1.

[0038] Example 4

[0039] The difference between Example 4 and Example 3 is that in step (2), the temperature of the catalytic section is kept constant at 450°C.

[0040] Example 5

[0041] The difference between Example 5 and Example 3 is that in step (2), the temperature of the catalytic section is kept constant at 550°C.

[0042] Example 6

[0043] The difference between Example 6 and Example 3 is: Preparation of TiAl catalyst: 15g of tetrabutyl titanate (Macklin) and 15g of γ-Al2O3 were mixed and added to anhydrous ethanol, stirred evenly until dry, left to stand overnight, calcined at 650°C for 5h, with a heating rate of 10°C / min, to obtain a TiAl catalyst, which was sieved through a 20-40 mesh screen. That is, the catalyst used in Example 6 only contained the semiconductor material Ti.

[0044] Example 7

[0045] The difference between Example 7 and Example 3 is: The Ni loading of the catalyst in Example 7 is 1 wt %.

[0046] Example 8

[0047] The difference between Example 8 and Example 3 is: The Ni loading of the catalyst in Example 8 is 15 wt %.

[0048] Comparative Example 1

[0049] (1) 4.5 g of plastic bottles (polypropylene) were crushed into 3 mm particles and placed in a pyrolysis system. The pyrolysis temperature was set to 500 °C, and argon was used as the carrier gas at a flow rate of 50 mL / min.

[0050] (2) Argon gas carries the pyrolysis vapor formed in step (1) into the catalytic section. The mass ratio of plastic to catalyst is 3:1. A conventional pure thermal catalytic experiment is carried out using argon as the carrier gas. The NiTiAl catalyst of comparative example 1 is the same as that of example 1. The temperature of the catalytic section is 500° C. After the temperature is constant, the reaction is started. The reaction time is 20 min.

[0051] (3) The condensable part of the pyrolysis vapor is condensed and collected as pyrolysis oil, and the non-condensable part is collected as combustible gas.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 3 is: Comparative Example 2 did not use the catalyst of the present application, but used a Ni-Ti catalyst. The preparation process of the Ni-Ti catalyst was as follows: The method of making the above Ni-Ti catalyst in the laboratory is as follows: 7.43 g Ni(NO3)2·6H2O is added to anhydrous ethanol and stirred evenly, and TiO2(P 25 ), stirred to dry, allowed to stand overnight, and calcined at 650 °C for 2 h with a heating rate of 10 °C / min to obtain a NiTi catalyst.

[0054] Comparative Example 2 used a commercially available catalyst, and the oil yield was 69.89%, but it was a waxy oil (which can be regarded as having an extremely poor catalytic effect).

[0055] The fuels prepared in the examples and comparative examples were subjected to GCMS testing, and the product distribution results of the fuels are shown in Table 1.

[0056] Table 1

[0057] Note: Oil yield = oil mass / plastic mass*100%; gasoline range yield = gasoline mass / oil mass*100%; aviation fuel range yield = aviation fuel mass / oil mass*100%.

[0058] It can be concluded from the above Examples 1 to 3 that, at the same pyrolysis temperature (500°C) and catalytic temperature (500°C), as the mass of the feedstock increases (1.5 to 4.5 g), the oil yield gradually increases. However, as the feedstock increases, due to the limited active sites of the catalyst, the catalytic effect on the pyrolysis vapor gradually decreases, the selectivity for gasoline and aviation fuel decreases, and more short-chain and unsaturated hydrocarbons are produced.

[0059] From the above examples 3 to 5, it can be concluded that when the ratio of raw materials to catalyst is fixed (3:1), the pyrolysis stage is kept at 500°C, and the catalytic temperature is changed (450-550°C), there are significant differences in the oil yield and the selectivity for gasoline and aviation fuel. As the temperature of the catalytic stage continues to increase, the oil yield gradually decreases, the bond breaking effect of the catalyst on CC bonds and CH bonds is enhanced, the selectivity for gasoline and aviation fuel is enhanced, and more gas and coke are produced.

[0060] It can be concluded from the above Examples 3, 6-8 that as the Ni loading increases, the oil yield shows a trend of first increasing and then decreasing. The loading of Ni promotes the cracking of CC bonds and CH bonds, making it easier for small molecular hydrocarbons in the product to be cracked into smaller gaseous products, such as H2, CH4, etc. At the same time, the Ni-loaded catalyst often has a strong dehydrogenation and cracking ability, but may not be as selective as the TiAl catalyst for hydrocarbon products with a specific carbon chain length, so the selectivity for the aviation fuel and gasoline range is reduced after Ni is loaded.

[0061] It can be concluded from the above-mentioned Example 3 and Comparative Example 1 that when the photothermal synergistic catalytic waste plastic pyrolysis system is compared with the traditional pure thermal catalytic waste plastic pyrolysis system, at the same ratio and temperature, the photothermal synergistic catalytic oil yield is increased by 8.79%, the selectivity for the gasoline range is increased by 20.74%, and the selectivity for the aviation fuel range is increased by 15.49%. The fuel quality is greatly improved, and the photothermal synergistic catalytic effect is significant.

[0062] It can be concluded from the above-mentioned Examples 1-8 and Comparative Example 2 that the catalyst of the present method has a strong catalytic ability under photothermal conditions. The present invention provides a method for preparing high-quality fuel oil by pyrolysis of a novel photothermal synergistic catalytic material, wherein plastic and a pyrolysis catalyst are placed in a reaction system, and a catalytic pyrolysis reaction is carried out with an inert gas as a carrier gas under the condition that the catalyst is irradiated by a solar light source, and finally high-quality fuel oil and combustible gas are obtained. The present invention proposes a new method for the high-value utilization of waste plastics, which can alleviate the increasing shortage of fossil energy while reducing the serious environmental pollution problems caused by the use of fossil energy. The production process is simple, the production process is clean, and the production cost can be reduced to the maximum extent.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing fuel oil by photothermal catalytic pyrolysis of plastics, characterized in that: include: (1) Pyrolyzing the plastic to obtain pyrolysis vapor; (2) subjecting the pyrolysis vapor to a catalytic reaction under a catalyst and light to obtain a mixed product; (3) Condensing the mixed product to obtain fuel oil.

2. The method according to claim 1, characterized in that: In step (1), the pyrolysis temperature is 375°C to 550°C.

3. The method according to claim 1 or 2, characterized in that: In step (1), the plastic includes at least one of low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate; And / or, the particle size of the plastic is 1 mm to 100 mm.

4. The method according to claim 1 or 2, characterized in that: Step (1) further comprises: introducing an inert gas, wherein the inert gas carries the pyrolysis vapor to move; And / or, the flow rate of the inert gas is not greater than 200 mL / min.

5. The method according to claim 1, characterized in that: In step (2), the catalyst includes a precursor and a support supported on the precursor, the precursor includes at least one of a metal oxide, a molecular sieve, and biochar, and the support includes a semiconductor material.

6. The method according to claim 5, characterized in that: Based on the total mass of the catalyst, the mass of the support accounts for 1% to 20%; And / or, the semiconductor material includes at least one of Ti, Si, and Ge; And / or, the support further comprises a metal, wherein the metal comprises at least one of nickel, iron and zinc; And / or, based on the total mass of the catalyst, the mass proportion of the metal is no more than 15%.

7. The method according to claim 1 or 5, characterized in that: The mass ratio of the plastic to the catalyst is (1-4):(2-1).

8. The method according to claim 1 or 5, characterized in that: In step (2), the temperature of the catalytic reaction is 375°C to 550°C, and the time of the catalytic reaction is 15 min to 40 min.

9. A fuel, characterized in that: Prepared by the method according to any one of claims 1 to 8.

10. The fuel according to claim 9, characterized in that: The mass proportion of C5~C12 gasoline in the fuel is not less than 70%, and the mass proportion of C8~C12 aviation fuel in the fuel is not less than 76%.

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