Method for converting waste polystyrene plastics into useful products by zero-valent iron photo-thermal conversion

Abstract

The present application relates to a kind of zero-valent iron photo-thermal conversion waste polystyrene plastic method, utilize nano zero-valent iron material as catalyst photo-thermal conversion waste polystyrene plastic, the nano zero-valent iron material has nanoscale scale, to be made with iron chloride and sodium borohydride as raw material.The present application compared with prior art, nano zero-valent iron material can be under solar irradiation high selectivity photo-thermal conversion waste polystyrene plastic into aviation kerosene and high carbon oil, waste polystyrene plastic conversion rate can be up to 98%, high carbon oil selectivity is more than 54%, long time reaction after catalyst can keep good cycle stability.

Description

TECHNICAL FIELD

[0001] The application relates to the field of environmental catalysis technology, and in particular to a method for converting waste polystyrene plastic into a zero-valent iron photo-thermal product. BACKGROUND

[0002] Traditional large-scale recycling of polystyrene plastic mainly relies on mechanical recycling, but there are many problems, such as low product density, potential secondary pollution, deterioration of recycled plastic quality and reduction of added value. Therefore, the commercial direct recycling value and recycling amount of waste polystyrene plastic are the lowest, leading some municipal authorities to consider banning the use of expanded polystyrene. Therefore, it is urgent to develop efficient, economic, low-carbon and environmentally friendly sustainable recycling technologies for waste polystyrene plastic. The chemical upgrading recycling method is to convert waste polystyrene plastic into high-value-added chemicals through chemical reaction, so as to realize its resource utilization. This strategy can realize the large-scale upgrading recycling of waste polystyrene plastic, and the generated high-value-added aromatic compounds can replace carbon-based fossil raw materials to some extent. From the perspective of economic circulation, the production of a large amount of polystyrene plastic consumes a large amount of styrene monomer, and the styrene monomer mainly comes from petroleum cracking and natural gas. Therefore, the high-value-added chemicals obtained by upgrading recycling of waste polystyrene are expected to realize their "value-added" and then enter the global economic cycle. From the perspective of molecular structure, the benzene group of polystyrene accounts for 75% of the total weight of the polymer, which is an excellent source of high-value-added aromatic compounds. However, all atoms of polystyrene are connected by C-C and C-H covalent bonds, which leads to its strong chemical inertness. Therefore, it is extremely challenging to chemically convert polystyrene, and its pyrolysis process requires high temperature (>500℃) to improve the conversion rate, and the external heat source increases the consumption of fossil energy, thereby increasing the cost of waste polystyrene treatment. Although traditional catalytic pyrolysis technology can use transition metal catalysts to convert polystyrene into small molecular aromatic hydrocarbons (toluene, ethylbenzene, styrene, etc.) at a lower reaction temperature (200-450℃), the high-pressure hydrogen gas or other coexisting reactants increase the process cost, resulting in a decrease in the economic value of the recycled products.

[0003] Solar energy, as an inexhaustible free energy on earth, is the best choice to replace traditional fossil energy. The technical feasibility of g-C3N4 photocatalytic oxidation to produce aromatic oxygen-containing derivatives (acetophenone, benzaldehyde, benzoic acid) has been proved, which can avoid excessive energy consumption to some extent, but has the shortcomings of low solar energy utilization efficiency, long reaction time and difficult product recovery. Photo-thermal catalysis is a kind of solar-driven photochemical and thermal chemical coupling catalysis, which can induce reactions to occur under solvent-free conditions by heating the reaction system or the catalyst through light. However, photo-thermal catalysis also has the problems of long reaction time and low light energy utilization rate, which are mainly due to the non-uniformity of light in the reaction system and the low light absorption-photothermal conversion efficiency of the catalytic material.

[0004] Patent CN202210551688.7 discloses a method for converting waste plastics into high-value fuel and environmental remediation materials by zero-valent iron photo-thermal conversion, which uses oxygen-containing acid radical modified zero-valent iron material as a catalyst for photo-thermal conversion of waste plastics. However, polystyrene plastic has a complex structure compared to conventional low-density polyethylene, and the cracking products are diverse and difficult to control, so the use of this catalyst to treat polystyrene plastic is not ideal. It is extremely challenging to develop a catalyst for cracking polystyrene plastic with high conversion rate and directional conversion capability. SUMMARY

[0005] The purpose of the present application is to provide a method for converting waste polystyrene plastic into gas fuel and liquid fuel by zero-valent iron photo-thermal conversion.

[0006] The purpose of the present application can be achieved by the following technical solution: a method for converting waste polystyrene plastic into gas fuel and liquid fuel by zero-valent iron photo-thermal conversion, which uses nano zero-valent iron material as a catalyst for photo-thermal conversion of waste polystyrene plastic. The nano zero-valent iron material has a nanoscale size and is prepared from ferric chloride and sodium borohydride.

[0007] Preferably, the nano zero-valent iron material has a particle diameter of 50-150 nm.

[0008] Preferably, the nano zero-valent iron material is in the form of nanowires with an iron oxide shell on the surface.

[0009] Preferably, the nano zero-valent iron material has a nanowire structure composed of nanoscale microspheres.

[0010] Preferably, the preparation method of the nano zero-valent iron material comprises the following steps: mixing ferric chloride solution and sodium borohydride solution at room temperature, filtering the suspension after aging, washing the obtained solid material and drying it in an inert atmosphere, and collecting the nano zero-valent iron material.

[0011] Further preferably, the concentration of the ferric chloride solution is 1-2 g / L.

[0012] Further preferably, the concentration of the sodium borohydride solution is 3-5 g / L.

[0013] Further preferably, the volume ratio of the ferric chloride solution to the sodium borohydride solution is (1.5-2.5):1.

[0014] Further preferably, the ferric chloride solution and the sodium borohydride solution are both aqueous solutions. The nano zero-valent iron material is prepared by aqueous phase reduction.

[0015] Further preferably, the ferric chloride solution is dripped into the sodium borohydride solution at a flow rate of 30-50 mL / min, and the mixture is reacted at room temperature for 50-70 min.

[0016] Further preferably, the inert atmosphere is nitrogen or argon.

[0017] Preferably, the aging time is 4-6 hours, and the drying time is 0.5-12 hours.

[0018] Further preferably, the aging time is 5 hours, and the drying time is 2-3 hours.

[0019] Preferably, the mass ratio of the nano zero-valent iron material to the waste polystyrene plastic is 1:5-1:1.

[0020] Preferably, the method for converting waste polystyrene plastic by zero-valent iron photo-thermal conversion is as follows: the nano zero-valent iron material is used as a catalyst, mixed uniformly with waste polystyrene plastic, inert protective gas is introduced into a photo-thermal reactor, a xenon lamp light source is used to simulate sunlight, and the obtained product is obtained.

[0021] Further preferably, the photo-thermal reaction time is 30-150 min.

[0022] Further preferably, the light power density is 0.5-5 W / cm 2 .

[0023] Further preferably, the waste polystyrene plastic is first crushed into a powder with a particle size of 0.08-0.12 mm by freeze-drying, i.e., a waste polystyrene plastic precursor, and then mixed with the nano zero-valent iron material.

[0024] Further preferably, in a closed stainless steel photo-thermal reactor equipped with a quartz glass window, the nano zero-valent iron material is used as a photo-thermal catalyst, mixed uniformly with the waste polystyrene plastic precursor, argon is then introduced into the photo-thermal reactor until no oxygen signal peak is detected in gas chromatography, a xenon lamp light source is used to simulate sunlight, and the obtained product is gaseous fuel and liquid fuel oil.

[0025] Preferably, the method for converting waste polystyrene plastic by zero-valent iron photo-thermal conversion uses the nano zero-valent iron material as a catalyst to photo-thermally convert waste polystyrene plastic to obtain product gaseous fuel and liquid fuel oil.

[0026] Further preferably, the gaseous fuel and liquid fuel oil include H2, C1-C4 alkane olefin, C8-C 16 aviation kerosene, C 16+ high-carbon oil.

[0027] Further preferably, the nano zero-valent iron material is used as a catalyst to photo-thermally convert waste polystyrene plastic to obtain product C8-C16 aviation kerosene, C 16+ high carbon oil.

[0028] The present application uses nano zero-valent iron material as a photo-thermal catalyst for polystyrene plastic cracking, which provides more surface active sites for C-C bond and C-H bond cracking due to its larger specific surface area. In particular, the plasmonic resonance effect of the nano zero-valent iron material can generate ultra-high local temperature, which can provide more energy for the reaction. Therefore, the nano zero-valent iron material of the present application is expected to become a new type of catalyst for efficient sunlight-driven waste polystyrene plastic conversion.

[0029] In the present application, the nano zero-valent iron is used to absorb ultraviolet-visible light in the solar spectrum to trigger traditional photochemical reactions, and the excitation state photochemistry and non-equilibrium state photo-thermal effect of infrared photons and carrier recombination process are used to reduce the reaction energy barrier, greatly improving the solar energy utilization efficiency and waste polystyrene plastic conversion rate. The temperature-dependent evaporation-separation process induced by the local high temperature of the nano catalyst and the environmental temperature difference is conducive to the selective generation of high carbon oil, and the solvent-free condition reduces the difficulty of product purification. Compared with traditional liquid-phase photocatalytic oxidation and thermal cracking, nano metal photo-thermal catalytic reaction has great advantages and prospects in the industrial application of waste polystyrene plastic resourceization.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] 1. The present application uses nano-sized zero-valent iron catalyst to photo-thermal catalyze waste polystyrene plastic, realizing efficient conversion into high-value gas fuel and liquid fuel;

[0032] 2. The present application uses a liquid-phase reduction method to successfully prepare a nano zero-valent iron that can efficiently photo-thermal convert waste polystyrene plastic, which can selectively photo-thermal upgrade waste polystyrene plastic into aviation kerosene and high carbon oil under solar irradiation;

[0033] 3. The present application uses the local high temperature of the nano catalyst and the environmental temperature difference to realize in-situ separation of the product, providing conditions for future industrial application;

[0034] 4. The zero-valent iron catalyst of the present application enables the conversion rate of waste polystyrene plastic to be as high as 98%, and the high carbon oil content to be more than 54%, and the catalyst can maintain good cycle stability after long-term reaction;

[0035] 5. The present application provides a new way for recycling and reusing waste polystyrene plastic with circular economy, environmental protection, low carbon and scalability, and the liquid product can be used as aviation kerosene and high carbon oil, realizing the simultaneous combination of waste polystyrene plastic resourceization and zero-carbon fuel production technology;

[0036] 6. The material of the present application is environmentally friendly, zero greenhouse gas emission, and the catalyst has good cycle stability, and the conversion rate of waste polystyrene plastic is higher than 90% during 10 cycles of test;

[0037] 7. The catalyst of the present application is synthesized from cheap and easily available raw materials, and has easy preparation conditions, simple experimental operation, no danger, and no need for complex devices.

[0038] 8. The zero-valent iron catalyst with nanometer size is synthesized by the aqueous phase reduction method, and has larger specific surface area and high efficient photo-thermal conversion efficiency, so that it has the ability of high directional conversion of pyrolysis of polystyrene plastic. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 XRD patterns of un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0040] Figure 2 SEM images of un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0041] Figure 3 TEM images of un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0042] Figure 4 Gas chromatograph-mass spectrometer combined detection of C8-C 16 aviation kerosene, C 16+ Change of high carbon oil content with catalyst size;

[0043] Figure 5 Photo-thermal conversion effect diagram of un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0044] Figure 6 Change of gas product content generated by photo-thermal conversion of waste polystyrene plastic by milled micron zero-valent iron;

[0045] Figure 7 Change of gas product content generated by photo-thermal conversion of waste polystyrene plastic by nano zero-valent iron;

[0046] Figure 8 Conversion rate of photo-thermal conversion of waste polystyrene plastic by un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0047] Figure 9 Change of liquid fuel content of photo-thermal conversion of waste polystyrene plastic without adding catalyst, adding un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron;

[0048] Figure 10The change in liquid fuel content of waste polystyrene plastic by photothermal conversion of nano-zero-valent iron under light conditions;

[0049] Figure 11 The changes in liquid fuel content in waste polystyrene plastics under air and argon atmospheres for photothermal conversion of nano-zero valent iron.

[0050] Figure 12 C8-C catalyzed by oxyanion-modified zero-valent iron and nano-zero-valent iron 16 Aviation kerosene, C 16+ High carbon oil content;

[0051] Figure 13 Liquid fuel conversion rates of ball-milled nano-sized zero-valent iron and nano-zero-valent iron prepared by the aqueous phase reduction method of this invention;

[0052] Figure 14 The liquid fuel conversion rate is calculated for different mass ratios of nano-zero-valent iron materials and waste polystyrene plastics.

[0053] Figure 15 Liquid fuel conversion rates of nano-zero valent iron prepared at different drying times;

[0054] Figure 16 This is a graph showing the cycling performance of nano-zero-valent iron materials. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0057] In the following examples, the waste polystyrene plastic sample used high-purity polystyrene powder (Ruixiang Plastics Co., Ltd.), and the unmilled micron-sized zero-valent iron used commercial iron powder.

[0058] Example 1

[0059] A method for photothermal conversion of waste polystyrene plastic with zero-valent iron includes the following steps:

[0060] Preparation of S1 nano-zero valent iron: 800 mL of 1.5 g / L ferric chloride aqueous solution was added dropwise to 400 mL of 4 g / L sodium borohydride aqueous solution at a flow rate of 40 mL / min. The mixture was reacted at room temperature for 1 h. After the reaction was completed, the mixture was aged for 5 h. The suspension was filtered by vacuum filtration, the solid was washed and dried in an inert atmosphere for 2.5 h, and the nano-zero valent iron material was collected.

[0061] S2. Realization of high-value-added gaseous and liquid fuels from waste polystyrene plastic through photothermal conversion: 0.2g of waste polystyrene plastic sample and 0.1g of nano-zero-valent iron material obtained in step S1 are mixed evenly. Argon gas is introduced into the photothermal reactor, and the oxygen content in the gas is sampled and detected until the oxygen concentration is below the detection threshold. A simulated solar light source is turned on at a light power of 4W / cm². 2 Photothermal conversion of waste polystyrene plastic was investigated, and the conversion rates of waste polystyrene plastic at different photothermal reaction times, as well as the conversion of H2 and C1-C4 gaseous fuels and C8-C4 fuels, were tested. 16 Aviation kerosene and C 16+ Yield and selectivity of high-carbon oils.

[0062] Comparative Example 1

[0063] A method for photothermal conversion of waste polystyrene plastic with zero-valent iron includes the following steps:

[0064] 0.2g of waste polystyrene plastic sample and 0.1g of unmilled micron-sized zero-valent iron were mixed thoroughly. Argon gas was introduced into a photothermal reactor, and the oxygen content in the gas was sampled and measured until the oxygen concentration was below the detection threshold. A simulated solar light source was turned on at a light power of 4W / cm². 2 Photothermal conversion of waste polystyrene plastic was investigated, and the conversion rates of waste polystyrene plastic at different photothermal reaction times, as well as the conversion of H2 and C1-C4 gaseous fuels and C8-C4 fuels, were tested. 16 Aviation kerosene and C 16+ Yield and selectivity of high-carbon oils.

[0065] Comparative Example 2

[0066] A method for photothermal conversion of waste polystyrene plastic with zero-valent iron includes the following steps:

[0067] Preparation of S1 ball-milled micron-sized zero-valent iron: 4.0g of unmilled micron-sized zero-valent iron was placed in an agate ball milling jar, and inert gas was introduced into the ball milling jar. The jar was ball-milled at 400 rpm for 4 hours. After naturally cooling to room temperature, the ball-milled micron-sized zero-valent iron material was collected.

[0068] S2. Realization of high-value-added gaseous and liquid fuels from waste polystyrene plastic through photothermal conversion: 0.2g of waste polystyrene plastic sample and 0.1g of ball-milled micron-sized zero-valent iron obtained in step S1 are mixed evenly. Argon gas is introduced into the photothermal reactor, and the oxygen content in the gas is sampled and detected until the oxygen concentration is below the detection threshold. A simulated solar light source is turned on at a light power of 4W / cm². 2 Photothermal conversion of waste polystyrene plastic was investigated, and the conversion rates of waste polystyrene plastic at different photothermal reaction times, as well as the conversion of H2 and C1-C4 gaseous fuels and C8-C4 fuels, were tested. 16 Aviation kerosene and C 16+ Yield and selectivity of high-carbon oils.

[0069] The zero-valent iron materials of Example 1, Comparative Example 1, and Comparative Example 2 were tested:

[0070] Figure 1 The images show the XRD patterns of unmilled micron-sized zero-valent iron, milled micron-sized zero-valent iron, and nano-sized zero-valent iron. As can be seen from the XRD patterns, the main component of the synthesized material is zero-valent iron.

[0071] Figure 2 The images show SEM images of un-ball-milled micron-sized zero-valent iron, ball-milled micron-sized zero-valent iron, and nano-sized zero-valent iron. The SEM images show that the particle size of un-ball-milled micron-sized zero-valent iron is 10–100 μm, that of ball-milled micron-sized zero-valent iron is 1–15 μm, and that of nano-sized zero-valent iron is 50–150 nm. (Figure a shows un-ball-milled micron-sized zero-valent iron, Figure b shows ball-milled micron-sized zero-valent iron, and Figure c shows nano-sized zero-valent iron)

[0072] Figure 3 The images show TEM images of un-ball-milled micron-sized zero-valent iron, ball-milled micron-sized zero-valent iron, and nano-sized zero-valent iron. Figures a and b show that the micron-sized zero-valent iron consists of irregular particles without a surface coating. Figure c shows that the nano-sized zero-valent iron has a nanowire structure with an iron oxide shell on its surface. (Figure a: Un-ball-milled micron-sized zero-valent iron; Figure b: Ball-milled micron-sized zero-valent iron; Figure c: Nano-sized zero-valent iron)

[0073] The experimental results of zero-valent iron in Example 1, Comparative Example 1, and Comparative Example 2 are analyzed as follows:

[0074] like Figure 4 C8-C in gas chromatography-mass spectrometry 16 Aviation kerosene and C 16+ The content of high-carbon oil varies with the size of the catalyst.

[0075] Figures 6-7 The changes in H2 and C1-C4 gaseous fuel content were detected by gas chromatography-mass spectrometry within 90 minutes of photothermal reaction of ball-milled micron-sized and nano-sized zero-valent iron.

[0076] Figure 8Conversion rate of polystyrene after 90 minutes of photothermal reaction.

[0077] From Figure 4 , 6 , it can be seen that, under the same conditions, the content of high-carbon oil obtained by using nano zero-valent iron as catalyst is as high as 54%, which is much higher than that of un-milled micron zero-valent iron and milled micron zero-valent iron.

[0078] From Figure 8 , it can be seen that the conversion rate of waste polystyrene pyrolyzed by nano zero-valent iron is as high as 98%, which is much higher than that of un-milled micron zero-valent iron (21%) and milled micron zero-valent iron (46%).

[0079] The photothermal conversion effects of un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron are shown in Figure 5 , and the temperature measurement results show that nano zero-valent iron has higher photothermal conversion efficiency, and its strong size effect and local nano high temperature greatly improve the conversion rate of waste polystyrene and the selectivity of high-carbon oil.

[0080] Comparative Example 3

[0081] Photothermal conversion of waste polystyrene plastic into gaseous fuel and liquid fuel without catalyst:

[0082] 0.2g of waste polystyrene plastic sample was mixed with 0.1g of nano zero-valent iron and then introduced into a photothermal reactor. Argon was introduced into the reactor, and the nitrogen content in the gas in the reactor was detected until the oxygen concentration was lower than the detection line. The simulated sunlight source was turned on, and the waste polystyrene plastic was photothermally converted under a light intensity of 4W / cm 2 . The conversion rate of waste polystyrene plastic into liquid fuel at different photothermal reaction times was tested. The experimental results are shown in Figure 9 : compared with un-milled micron zero-valent iron, milled micron zero-valent iron and nano zero-valent iron, the waste polystyrene plastic cannot be converted into liquid fuel by photothermal reaction without catalyst.

[0083] Comparative Example 4

[0084] Thermal conversion of waste polystyrene plastic into gaseous fuel and liquid fuel without light:

[0085] 0.2g of waste polystyrene plastic sample was mixed with 0.1g of nano zero-valent iron and then introduced into a photothermal reactor. Argon was introduced into the reactor, and the nitrogen content in the gas in the reactor was detected until the oxygen concentration was lower than the detection line. The experimental results are shown in Figure 10 : compared with light conditions, the nano zero-valent iron under non-light conditions cannot convert waste polystyrene plastic into liquid fuel.

[0086] Comparative Example 5

[0087] Photothermal conversion of waste polystyrene plastic into gaseous fuel and liquid fuel in air atmosphere:

[0088] A 0.2 g sample of waste polystyrene plastic and 0.1 g of nano zero-valent iron were mixed uniformly, and air was introduced into a photo-thermal reactor. A simulated sunlight source was turned on, and the light intensity was 4 W / cm2. The reactor was kept at 25 °C, and the reaction was carried out for 24 h. The reactor was taken out, and the gas in the reactor was collected and analyzed. The results are shown in Table 1. 2 The waste polystyrene plastic was photo-thermally converted, and the conversion rate of the waste polystyrene plastic to liquid fuel was tested at different photo-thermal reaction times. The experimental results are shown in Table 2. Figure 11 As shown in Table 2, compared with the nano zero-valent iron in an inert atmosphere, the nano zero-valent iron in an air atmosphere cannot convert the waste polystyrene plastic to liquid fuel by photo-thermal reaction.

[0089] Comparative Example 6

[0090] Oxygen-containing acid group modified zero-valent iron photo-thermally converts waste polystyrene plastic to gaseous fuel and liquid fuel:

[0091] A 0.2 g sample of waste polystyrene plastic and 0.1 g of boro-phosphate co-modified zero-valent iron (the surface boro acid group content is 2 wt%, the surface phospho acid group content is 2.6 wt%, and the particle size is 0.3-5 μm) were mixed uniformly, and argon was introduced into a photo-thermal reactor. The nitrogen content in the gas in the reactor was detected by sampling until the oxygen concentration was lower than the detection line. The experimental results are shown in Table 3. Figure 12 As shown in Table 3, the liquid fuel content produced by the oxygen-containing acid group modified zero-valent iron in converting the waste polystyrene plastic is significantly lower than that of the nano zero-valent iron.

[0092] Comparative Example 7

[0093] Ball-milled nano zero-valent iron photo-thermally converts waste polystyrene plastic to gaseous fuel and liquid fuel:

[0094] Preparation of ball-milled nano zero-valent iron: 0.5 g of silicic acid precursor and 5 g of zero-valent iron were mechanically ball-milled at 400 rpm for 8 h in an inert atmosphere. After natural cooling to room temperature, the ball-milled nano zero-valent iron material was collected, and the size was 20-800 nm.

[0095] A 0.2 g sample of waste polystyrene plastic and 0.1 g of ball-milled nano zero-valent iron were mixed uniformly, and argon was introduced into a photo-thermal reactor. The nitrogen content in the gas in the reactor was detected by sampling until the oxygen concentration was lower than the detection line. The experimental results are shown in Table 4. Figure 13 As shown in Table 4, compared with the nano zero-valent iron prepared by the aqueous phase reduction method, the conversion rate of the ball-milled nano zero-valent iron in converting the waste polystyrene plastic to liquid fuel is significantly lower than that of the nano zero-valent iron prepared by the aqueous phase reduction method.

[0096] Example 2

[0097] In this example, the nano zero-valent iron material dosage and the waste polystyrene plastic mass ratio were set to 1:5, and the rest was the same as in Example 1. The experimental results are shown in Table 5. Figure 14As shown: the nano zero-valent iron material can transform waste polystyrene plastic into liquid fuel under the condition of the mass ratio of dosage to waste polystyrene being 1:5.

[0098] Example 3

[0099] In this example, the drying time during the synthesis of nano zero-valent iron is set to 0.5h, and the rest is the same as example 1. The experimental results are as follows Figure 15 As shown: the nano zero-valent iron material synthesized under the condition of material drying time being 0.5h can transform waste polystyrene plastic into liquid fuel.

[0100] Example 4

[0101] In this example, 0.2g of waste polystyrene plastic is mixed with the catalyst after reaction, and the photo-thermal reforming is continued for 90 minutes, and the rest is the same as example 1. The experimental results are as follows Figure 16 As shown: the nano zero-valent iron material has good recycling performance in the photo-thermal transformation of waste polystyrene plastic.

[0102] The above description of examples is for the convenience of ordinary skilled persons in the art to understand and use the invention. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without creative labor. Therefore, the present application is not limited to the above examples, and the improvements and modifications made by those skilled in the art according to the disclosure of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method of photo-thermal conversion of waste polystyrene plastic by zero-valent iron, characterized by, The application discloses a method for photo-thermal conversion of waste polystyrene plastic by using nano zero-valent iron material as a catalyst, wherein the nano zero-valent iron material has a nano-scale size and is prepared from ferric chloride and sodium borohydride. The nano zero-valent iron material has a particle diameter of 50-150 nm. The nano zero-valent iron material has a nanowire structure and an iron oxide shell on the surface. The preparation method of the nano zero-valent iron material comprises the following steps: mixing a ferric chloride solution and a sodium borohydride solution at room temperature, filtering the suspension after aging, washing the obtained solid material and drying the solid material in an inert atmosphere, and collecting the nano zero-valent iron material. The concentration of the ferric chloride solution is 1-2 g / L. The concentration of the sodium borohydride solution is 3-5 g / L. The volume ratio of the ferric chloride solution to the sodium borohydride solution is (1.5-2.5):

1. The ferric chloride solution and the sodium borohydride solution are both aqueous solutions. The ferric chloride solution is dropped into the sodium borohydride solution at a flow rate of 30-50 mL / min, and the mixture is reacted at room temperature for 50-70 min. The method for photo-thermal conversion of waste polystyrene plastic by using the nano zero-valent iron material as a catalyst can obtain product gas fuel and liquid fuel. The gaseous and liquid fuels include H2, C8-C 16 Aviation kerosene, C 16+ High carbon oil.

2. The method of converting waste polystyrene plastics to fuels by zero-valent iron photo-thermal conversion according to claim 1, characterized in that, The aging time is 4-6 hours, and the drying time is 0.5-12 hours.

3. The method of converting waste polystyrene plastics to fuels and chemicals by zero-valent iron photo-thermal conversion according to claim 1, wherein, The mass ratio of the nano zero-valent iron material to the waste polystyrene plastic is 1:5-1:

1.

4. The method of converting waste polystyrene plastics to fuels and chemicals by zero-valent iron photo-thermal conversion according to claim 1, wherein, Specifically, the nano zero-valent iron material is used as a catalyst to uniformly mix with waste polystyrene plastic, inert protective gas is introduced into a photo-thermal reactor, a xenon lamp light source is used to simulate sunlight, and the obtained product is obtained.

5. The method of converting waste polystyrene plastics to fuels by zero-valent iron photo-thermal conversion according to claim 4, wherein, The photo-thermal reaction time is 30-150 min.

6. The method of converting waste polystyrene plastics to fuels by zero-valent iron photo-thermal conversion according to claim 4, wherein, Optical power density is 0.5-5 W / cm 2 .

Images