Photocatalysis method for degrading polystyrene into benzoic acid
By using FPQL-OMe and ferric trifluoromethanesulfonate as a synergistic photocatalyst in a mixed solvent of acetonitrile and chlorobenzene, the rapid and efficient degradation of polystyrene into benzoic acid was achieved. This solved the problems of low catalyst activity and long reaction time in the existing technology, and realized a highly efficient and economical degradation of polystyrene into benzoic acid.
Patent Information
- Application Number
- CN202511876294.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-05-15
AI Technical Summary
Existing photocatalytic degradation methods for polystyrene suffer from problems such as low catalyst activity, long reaction time, unsatisfactory product selectivity and yield, and unsuitable light source conditions, making it difficult to achieve efficient and economical degradation of polystyrene into benzoic acid.
FPQL-OMe and ferric trifluoromethanesulfonate were used as photocatalysts to carry out photocatalytic reactions in a mixed solvent of acetonitrile and chlorobenzene. The in-situ synergistic effect of the catalysts enhanced light absorption and electron transfer, enabling rapid and efficient degradation of polystyrene into benzoic acid.
At room temperature and pressure, polystyrene can be converted into benzoic acid with high yield and high selectivity using visible light. The amount of catalyst used is reduced by 1-2 orders of magnitude, the reaction time is shortened to 3 hours, and there are fewer by-products, which reduces energy consumption and processing costs.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic synthesis technology and relates to a photocatalytic method for degrading polystyrene and converting it into benzoic acid with high catalytic activity and high reaction rate. Background Technology
[0002] Polystyrene is a commercially available plastic with a massive production capacity, exceeding 15 million tons globally in 2020. It is widely used in industrial manufacturing sectors such as electronics, medical equipment, decorative packaging, and building materials. However, while polystyrene products greatly facilitate our lives, their stable chemical properties make them difficult to degrade in the natural environment. Traditional methods of waste polystyrene disposal, such as landfilling, cause long-term soil and groundwater pollution; incineration produces toxic gases and leads to carbon emissions; and mechanical recycling yields recycled materials with degraded performance, especially expanded polystyrene (EPS), which suffers from particularly low recycling rates due to its large size and high recycling costs. Therefore, developing a new technology that enables efficient and low-cost chemical recycling of polystyrene and the production of high-value chemicals is of great significance for solving "white pollution" and achieving resource recycling.
[0003] The degradation and recycling of polystyrene needs to avoid new environmental pollution as much as possible. From a molecular structure perspective, aryl groups account for 74% of polystyrene. Therefore, depolymerizing the polystyrene backbone to degrade it and convert it into aromatic monomers is theoretically feasible. This strategy can not only treat polystyrene waste but also potentially yield valuable basic chemicals, meeting the requirements of green and sustainable development in modern chemical industry. Early degradation methods mainly relied on thermal cracking, which often requires the addition of strong acids and strong oxidants and depends on high temperature (200℃-400℃) and high pressure (above 3 bar) reaction conditions. In 2021, the YAN research group achieved polystyrene degradation through high-temperature catalytic hydrogenolysis, obtaining abundant aromatic monomers such as cumene, ethylbenzene, and toluene. Although the conditions were harsh and the selectivity was low, this early work greatly promoted the discovery of high-value-added products from polystyrene degradation. In 2023, the Zhang and Williams research groups respectively degraded polystyrene through different thermal oxidative cracking methods and selectively converted it into benzoic acid in high yield. However, both thermal hydrogenolysis and thermal oxidative cracking suffer from high energy consumption, demanding equipment requirements, and high risk factors, especially the potential for secondary pollution due to increased side reactions. In recent years, photocatalysis has seen rapid development in synthetic chemistry and the degradation of environmental pollutants, offering advantages such as mild conditions, controllable selectivity, and environmental friendliness. Chemists, utilizing various photocatalytic systems—such as ferric chloride, organic small-molecule catalysts, and inorganic heterogeneous photocatalysts—in conjunction with other additives, have achieved the conversion of polystyrene to benzoic acid. This provides a new approach for the recycling and efficient utilization of polystyrene.
[0004] However, the currently reported methods for photocatalytic degradation of polystyrene still have significant shortcomings, which severely limit their practical application:
[0005] (1) Low catalytic activity of photocatalyst: In order to achieve a considerable benzoic acid yield (e.g., >50%), extremely high catalyst loading (>5mol%) and extremely long reaction time (tens of hours or more) are usually required, resulting in low efficiency and high cost;
[0006] (2) Unsatisfactory product yield and selectivity: The yield of benzoic acid in most methods is less than 60%, and there are a variety of by-products, which are difficult to separate and purify, reducing the overall economic efficiency.
[0007] (3) The light source conditions are not promising: the reaction relies on ultraviolet or deep blue light sources with wavelengths less than 400nm, which have poor matching with the solar spectrum and are difficult to develop towards a more economical and green solar energy-driven direction.
[0008] Therefore, how to provide a photocatalytic system with ultra-high catalytic activity, ultra-fast reaction rate and within the visible light catalytic range, while possessing both high product selectivity and high product yield, to achieve efficient and economical degradation of polystyrene, is a technical problem that urgently needs to be solved in this field. Summary of the Invention
[0009] The purpose of this invention is to address the problems in the prior art by providing a mild, efficient, and highly selective photocatalytic degradation method for polystyrene, which degrades polystyrene and converts it into benzoic acid with high yield and high added value.
[0010] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:
[0011] A photocatalytic method for degrading polystyrene to benzoic acid, characterized by comprising the following steps:
[0012] Polystyrene was dissolved in a mixed solvent containing acetonitrile and chlorobenzene, and the catalyst FPQL-OMe and ferric trifluoromethanesulfonate were added. The reaction was carried out under oxygen atmosphere and light conditions to produce benzoic acid.
[0013] In this process, FPQL-OMe and ferric trifluoromethanesulfonate work synergistically as a photocatalyst. Through the in-situ synergistic effect of FPQL-OMe and ferric trifluoromethanesulfonate, enhanced light absorption and efficient electron transfer are achieved, thereby improving photocatalytic performance.
[0014] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:
[0015] As a preferred embodiment of the present invention, the volume ratio of acetonitrile to chlorobenzene in the mixed solvent is 1:1.
[0016] As a preferred embodiment of the present invention: the amount of FPQL-OMe is 0.1 mol% to 1 mol of the amount of polystyrene repeating unit; the amount of ferric trifluoromethanesulfonate is 0.1 mol% to 1 mol of the amount of polystyrene repeating unit.
[0017] As a preferred embodiment of the present invention, the molar ratio of FPQL-OMe to ferric trifluoromethanesulfonate is 1:1.
[0018] As a preferred embodiment of the present invention, the reaction is carried out at a temperature of 15°C to 35°C.
[0019] As a preferred technical solution of the present invention, the reaction is characterized in that it is carried out under an oxygen atmosphere at normal pressure.
[0020] As a preferred technical solution of the present invention, the reaction time is 3 hours.
[0021] As a preferred embodiment of the present invention, the illumination is provided by a light source with a wavelength of 405 nm.
[0022] This invention provides a method for degrading polystyrene to obtain benzoic acid, a valuable basic chemical. A photocatalytic system is constructed using the compound FPQL-OMe and ferric trifluoromethanesulfonate. Depending on the catalyst dosage, the benzoic acid yield ranges from 0.1 mol% to 1.0 mol%, achieving benzoic acid yields of 42% to 65%. This method avoids the traditional thermal degradation route of polystyrene. Compared to existing photocatalytic polystyrene degradation methods, it employs a novel combination of photocatalyst and solvent, representing a green, safe, and environmentally friendly method for polystyrene degradation and recycling.
[0023] Compared with existing technologies, the photocatalytic method for degrading polystyrene to benzoic acid in this invention has the following beneficial effects: In this invention, the trifluoromethanesulfonate ion of Fe(OTf)3 has a strong polarizing effect, which generates hydrogen bonds and solvation effects with the electron-rich quinoline unit of FPQL-OMe, stabilizing the catalytic system and significantly enhancing the UV-Vis absorption of the photosensitizer in the 400-450 nm range; Fe(III) is a highly efficient electron acceptor, which can achieve rapid electron transfer with the photosensitizer, promote the generation of reactive oxygen species, and achieve efficient electron transfer, thereby greatly improving the efficiency of the photocatalytic process. The photon utilization rate and catalytic cycle efficiency are significantly improved through the dual effects of enhanced light absorption and promoted electron transfer, resulting in a substantial reduction in catalyst dosage and a significant shortening of reaction time. This achieves ultra-high catalytic activity and ultra-fast reaction rate, effectively solving the problems of low catalyst activity, high loading, and long reaction time. In this invention, the highly polar solvent acetonitrile is selected, which significantly increases the dissolved oxygen concentration in the reaction system, providing a sufficient oxidant source for the photocatalytic oxidation process. Its polar properties help stabilize the polar intermediates generated during the reaction, reducing the probability of side reactions. The use of the weakly polar solvent chlorobenzene further enhances this effect. The structural similarity with polystyrene facilitates efficient initial dissolution of polystyrene, ensuring sufficient contact of reactants in a homogeneous system. Chlorobenzene, through its solvation effect, specifically guides the breaking of C–C bonds, making the degradation process more inclined towards the formation of benzoic acid precursors. The reaction microenvironment is synergistically regulated through a polar / weakly polar mixed solvent. Fe(OTf)3 not only acts as an additive, forming a highly efficient in-situ non-coordinating synergistic system with the photosensitizer FPQL-OMe in a mixed solvent through hydrogen bonding and solvation, significantly enhancing light absorption and electron transfer efficiency, but also, as a strong Lewis acid… This invention can selectively activate specific chemical bonds in polystyrene chains, guiding the oxidative chain-breaking process along the path of benzoic acid formation, effectively inhibiting the formation of other excessive oxidation or random chain-breaking byproducts, thereby increasing the reaction rate while achieving high selectivity for benzoic acid products. In this invention, the synergistic effect of the mixed solvent and Fe(OTf)3 jointly constructs a multifunctional reaction environment with high solubility, efficient mass transfer, selective activation, and enhanced light absorption, enabling polystyrene to be rapidly and directionally converted into benzoic acid under visible light, simultaneously achieving high yield, high selectivity, and high reaction efficiency.
[0024] In this invention, the photosensitizer FPQL-OMe possesses an extended conjugated structure and an electron-rich quinoline unit, exhibiting excellent visible light capture potential. The introduced ferric trifluoromethanesulfonate (Fe(OTf)3) exhibits extremely strong charge polarization ability. In an acetonitrile / chlorobenzene mixed solvent, the two form dynamic molecular aggregates through hydrogen bonding and solvation effects. Non-covalent interactions alter the local electronic environment and molecular packing state of the photosensitizer, leading to a significant redshift and enhancement of its UV-Vis absorption spectrum, particularly in the 400–450 nm visible light region. This allows for efficient utilization of photons in this wavelength range, extending the traditional UV-dependent (<400 nm) reaction to visible light-driven conditions, and significantly improving the matching degree with the solar spectrum. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the degradation reaction route of polystyrene and the structure of the compound FPQL-OMe;
[0026] Figure 2 The UV-vis spectrum of compound FPQL-OMe in synergistic reaction with ferric trifluoromethanesulfonate;
[0027] Figure 3 The photocatalytic degradation yields of commercial polystyrene samples with different molecular weights in this invention;
[0028] Figure 4 The actual photocatalytic degradation yield of recycled polystyrene products in this invention is shown. Detailed Implementation
[0029] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
[0030] To address the problem of low degradation efficiency of polystyrene due to low catalytic activity in existing technologies, a photocatalytic system with ultra-high reactivity and ultra-fast reaction rate is provided to rapidly and efficiently degrade polystyrene into benzoic acid.
[0031] Therefore, the above-mentioned objectives of the present invention are achieved through the following technical solutions:
[0032] A photocatalytic method for degrading polystyrene to benzoic acid, the reaction route is as follows: Figure 1 As shown, the specific steps are as follows:
[0033] Using compound FPQL-OMe and ferric trifluoromethanesulfonate as effective catalytic components in the photocatalytic system, and a 1:1 volume ratio of acetonitrile and chlorobenzene as the reaction solvent, polystyrene was photodegraded at room temperature for a certain period of time in an oxygen atmosphere at normal pressure to obtain benzoic acid.
[0034] This application describes FPQL-Ome as a fluorinated, methoxylated quinoline carboxynitrile derivative with the following structural formula: .
[0035] The polystyrene substrate was 0.3 mmol, the solvent was 1 mL, the FPQL-OMe equivalent was 1 mol%, and the ferric trifluoromethanesulfonate equivalent was 1 mol%. The reaction was carried out under 405 nm light for 3 h, and the benzoic acid yield was 65% by HPLC (using methyl benzoate as a reference).
[0036] As a preferred embodiment of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 1 mol%, the ferric trifluoromethanesulfonate equivalent is 2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 62% by HPLC.
[0037] As a preferred embodiment of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 50% by HPLC.
[0038] As a preferred embodiment of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 0.1 mol%, the ferric trifluoromethanesulfonate equivalent is 0.1 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 42% by HPLC.
[0039] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 0.2 mol%, ferric chloride with an equivalent of 0.2 mol% is selected, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 29% by HPLC.
[0040] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 0.2 mol%, ferric bromide with an equivalent of 0.2 mol% is selected, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 33% by HPLC.
[0041] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the FPQL-OMe equivalent is 0.2 mol%, and 0.2 mol% acetylacetone iron(III) is selected. The reaction is carried out under 405 nm light for 3 h. The benzoic acid yield is 39% by HPLC.
[0042] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the ferric trifluoromethanesulfonate is 0.2 mol%, and 9-fluorenone with an equivalent of 0.2 mol% is selected as the photosensitizer. The reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 45% by HPLC.
[0043] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the iron equivalent of trifluoromethanesulfonate is 0.2 mol%, and p-toluenesulfonic acid with an equivalent of 0.2 mol% is selected as the photosensitizer. The reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 23% by HPLC.
[0044] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, and 4CZIPN (2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile) with an equivalent of 0.2 mol% is used as a photosensitizer. The reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 28% by HPLC.
[0045] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL LDMF (N,N-dimethylformamide), the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 0% by HPLC.
[0046] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL ethyl acetate, the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 1% by HPLC.
[0047] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL chlorobenzene, the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 15% by HPLC.
[0048] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL acetonitrile, the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 0% by HPLC.
[0049] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL of 1,2-dichloromethane, the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 11% by HPLC.
[0050] As a comparative technical solution of the present invention: the polystyrene substrate is 0.3 mmol, the solvent is 1 mL of 1,2-dichloromethane / acetonitrile (v:v=1:1), the FPQL-OMe equivalent is 0.2 mol%, the ferric trifluoromethanesulfonate equivalent is 0.2 mol%, the reaction is carried out under 405 nm light for 3 h, and the benzoic acid yield is 23% by HPLC.
[0051] This invention provides a method for degrading polystyrene to obtain benzoic acid, a valuable basic chemical. Optimal catalytic effect is achieved by using compound FPQL-OMe and ferric trifluoromethanesulfonate as a photocatalyst, with benzoic acid yields ranging from 42% to 65% depending on the catalyst dosage, from 0.1 mol% to 1.0 mol%. This method avoids the traditional technical route of polystyrene thermal degradation. Compared with existing photocatalytic polystyrene degradation methods, it employs a novel photocatalytic system, making it a green, safe, and environmentally friendly method for polystyrene degradation and recycling.
[0052] The present invention has the following beneficial effects:
[0053] 1. The method provided by this invention has mild reaction conditions and is green and safe: it completely avoids the use of strong acids and strong oxidants, does not require heating or pressurization, and can be carried out efficiently under normal temperature and pressure, oxygen atmosphere and visible light (405nm) irradiation. It greatly reduces energy consumption, equipment requirements and safety risks, and is an environmentally friendly plastic upgrading and recycling strategy.
[0054] 2. This invention proposes and verifies for the first time a novel photocatalytic polystyrene degradation system using FPQL-OMe and ferric trifluoromethanesulfonate in synergy for polystyrene degradation: FPQL-OMe and ferric trifluoromethanesulfonate are directly physically mixed in the mixed solvent, existing in a non-complex form. FPQL-OMe possesses conjugated and electron-rich quinoline units, and the trifluoromethanesulfonate ion has a strong polarization effect. In the mixed solvent of acetonitrile and chlorobenzene, the two readily generate hydrogen bonding interactions and solvation effects, resulting in a significantly enhanced ultraviolet-visible light absorption of the photosensitizer in the 400–450 nm range. This significantly enhances the visible light capture ability of the reaction system, improves the photon utilization rate of the photosensitizer, and thus greatly improves the photocatalytic performance, laying the foundation for utilizing visible light sources and even sunlight.
[0055] 3. Significantly improved catalytic efficiency and selectivity: Compared with the photocatalytic systems reported in existing literature and related patents that require >5 mol% catalyst and reaction time of tens of hours, the method disclosed in this invention reduces the amount of catalyst by 1-2 orders of magnitude (as low as 0.1 mol%) and significantly shortens the reaction time to 3 hours. Under optimized conditions (such as 1 mol% catalyst and 3 hours of reaction), the yield of benzoic acid can reach 65%. At the same time, the reaction selectivity is extremely high. In addition to the target product benzoic acid, the total amount of detectable organic byproducts is less than 1%, which greatly simplifies the product separation and purification process and reduces subsequent processing costs.
[0056] 4. Wide substrate applicability: This method shows good degradation effect and yield stability for commercial polystyrene of different molecular weights as well as polystyrene products from various sources of actual household waste (such as foam boards, plastic cups, bottle caps, etc.).
[0057] This invention utilizes FPQL-OMe as a photosensitizer and ferric trifluoromethanesulfonate as an additive in a specific mixed solvent of acetonitrile and chlorobenzene. No complex preparation is required; FPQL-OMe and ferric trifluoromethanesulfonate are directly physically mixed in this mixed solvent, existing as a non-complex compound. FPQL-OMe possesses conjugated and electron-rich quinoline units, and the trifluoromethanesulfonate ion exhibits strong polarization. In the mixed solvent of acetonitrile and chlorobenzene, these two readily generate hydrogen bonding interactions and solvation effects, resulting in significantly enhanced UV-Vis absorption of the photosensitizer within the 400–450 nm range. This improves the photon utilization rate of the photosensitizer, thereby greatly enhancing its photocatalytic performance.
[0058] The photocatalytic polystyrene degradation scheme involved in this invention greatly improves the photocatalytic reaction activity compared with existing photocatalytic methods. Specifically, the catalyst dosage is reduced by 1-2 orders of magnitude, the reaction time is significantly shortened, and the yield of all organic by-products is less than 1%. It converts polystyrene into benzoic acid in one step with excellent photoreaction efficiency, high selectivity, and high yield, and has significant advantages in terms of cost, energy consumption, and product purification.
[0059] Example 1
[0060] This invention provides a photocatalytic synthesis method for degrading polystyrene into benzoic acid.
[0061] A photocatalytic method for degrading polystyrene to benzoic acid, the method comprising the following steps: using a mixed solvent of acetonitrile and chlorobenzene as a reaction solvent, using compound FPQL-OMe and ferric trifluoromethanesulfonate in synergy as a photocatalyst, and photo-reacting polystyrene at room temperature for a period of time under an oxygen atmosphere to obtain benzoic acid monomer.
[0062] The volume ratio of acetonitrile to chlorobenzene in the mixed solvent is 1:1.
[0063] The preferred molar ratio of FPQL-OMe to polystyrene (in repeating units) is 1 mol, and the preferred molar ratio of ferric trifluoromethanesulfonate to polystyrene is 1 mol.
[0064] 4. The method according to claim 1, wherein the preferred molar ratio of FPQL-OMe to polystyrene (in repeating units) is 0.2 mol%, and the preferred molar ratio of ferric trifluoromethanesulfonate to polystyrene is 0.2 mol%.
[0065] The preferred molar ratio of FPQL-OMe to polystyrene (in repeating units) is 0.1 mol, and the preferred molar ratio of ferric trifluoromethanesulfonate to polystyrene is 0.1 mol.
[0066] The reaction time is 3 hours.
[0067] The reaction temperature is room temperature, and it is suitable for an ambient temperature range of 15 degrees Celsius to 35 degrees Celsius. Heating of the photoreactor is not required.
[0068] The oxygen is at normal pressure; it is only necessary to maintain an oxygen atmosphere, and no pressurization is required.
[0069] The present invention discloses a photocatalytic method for degrading polystyrene into benzoic acid, which mainly includes the following steps: polystyrene is reacted at room temperature (in any season, a 15°C condenser is required to control the temperature of the photoreactor) for 3 hours to obtain benzoic acid monomer. The catalyst is a mixture of FPQL-OMe and ferric trifluoromethanesulfonate, and the solvent is chlorobenzene and acetonitrile in equal volume ratio, with a total volume of 1 mL. The reaction device provides an oxygen environment by inserting an oxygen ball.
[0070] This embodiment studies the photocatalytic degradation reaction of commercial polystyrene samples, such as... Figure 3 , Figure 4 As shown:
[0071] A mixed solution of 1 mol% FPQL-OMe and 1 mol% ferric trifluoromethanesulfonate in acetonitrile / chlorobenzene (volume ratio 1:1) was prepared in a glove box under a nitrogen atmosphere. 1 mL of this mixed solution was added to several transparent glass reactors. Then, 31.2 mg of polystyrene with different weight-average molecular weights was weighed and dissolved in the mixed solution in the reactor. The reactors were sealed with rubber stoppers. The mixed solutions were then bubbled with oxygen bulbs for 3 minutes. After that, oxygen bulbs were inserted into the photoreactor, and the reaction was stirred for 3 hours under a 9 W light source at a wavelength of 405 nm. Samples were taken and the benzoic acid yields were measured by HPLC to be 60%, 65%, 55%, and 53% respectively (from i–iv, with methyl benzoate as a reference).
[0072] This embodiment studies the photocatalytic degradation reaction of recycled polystyrene products from daily life, such as... Figure 3 , Figure 4 As shown:
[0073] Prepare a 1 mol% FPQL-OMe and 1 mol% ferric trifluoromethanesulfonate acetonitrile / chlorobenzene mixed solution (volume ratio 1:1) in a glove box under nitrogen atmosphere. Add 1 mL of this mixed solution to several transparent glass reactors. Then weigh 31.2 mg of different recovered polystyrene products and their mixed samples (from v–xiv, in order: plastic cup, white foam board, bottle cap, plastic tube, XPS foam board, white foam board-plastic tube, plastic cup-bottle cap, plastic cup-XPS foam board, bottle cap-XPS foam board, plastic cup-white foam board). The mixture of colored foam board, bottle cap, plastic tube, and XPS foam board was dissolved separately in the mixed solution in the reactor. The reactor was then sealed with a rubber stopper. The mixed solution was then bubbled with an oxygen bulb for 3 minutes. The oxygen bulb was then inserted into the photoreactor and stirred for 3 hours under a 9-watt light source at a wavelength of 405 nm. Samples were taken and the yields of benzoic acid were measured by HPLC to be 58%, 55%, 54%, 56%, 51%, 55%, 57%, 55%, 52%, and 53% respectively (from v–xiv, with methyl benzoate as a reference).
[0074] The above specific embodiments are used to explain and illustrate the present invention, and are only preferred embodiments of the present invention, not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.
Claims
1. A photocatalytic method for degrading polystyrene to benzoic acid, characterized in that, Includes the following steps: Polystyrene was dissolved in a mixed solvent containing acetonitrile and chlorobenzene, and the catalyst FPQL-OMe and ferric trifluoromethanesulfonate were added. The reaction was carried out under oxygen atmosphere and light conditions to produce benzoic acid. In this process, FPQL-OMe and ferric trifluoromethanesulfonate work synergistically as a photocatalyst. Through the in-situ synergistic effect of FPQL-OMe and ferric trifluoromethanesulfonate, enhanced light absorption and efficient electron transfer are achieved, thereby improving photocatalytic performance.
2. The photocatalytic method as described in claim 1, characterized in that, The volume ratio of acetonitrile to chlorobenzene in the mixed solvent is 1:
1.
3. The photocatalytic method as described in claim 1, characterized in that, The amount of FPQL-OMe used is 0.1 mol% to 1 mol of the polystyrene repeating unit; the amount of ferric trifluoromethanesulfonate used is 0.1 mol% to 1 mol of the polystyrene repeating unit.
4. The photocatalytic method according to claims 1 and 3, characterized in that, The molar ratio of FPQL-OMe to ferric trifluoromethanesulfonate is 1:
1.
5. The photocatalytic method as described in claim 1, characterized in that: The reaction was carried out at a temperature between 15°C and 35°C.
6. The photocatalytic method as described in claim 1, characterized in that: The reaction was carried out under an oxygen atmosphere at normal pressure.
7. The photocatalytic method as described in claim 1, characterized in that: The reaction time is 3 hours.
8. The photocatalytic method as described in claim 1, characterized in that, The illumination is provided by a light source with a wavelength of 405 nm.