Cu / tiO2 composite material, and preparation method and application thereof

Abstract

This invention provides a Cu / TiO2 composite material, its preparation method, and its applications, belonging to the field of catalytic pyrolysis technology. By defining the template agent and reaction medium, this invention can obtain titanium dioxide nanosheets with high specific surface area and good catalytic pyrolysis activity. Using titanium dioxide nanosheets as the main body of the composite material increases contact with polyethylene molecular chains, causing the polyethylene molecular chains to break. In-situ loading of Cu provides abundant active sites and lowers the energy barrier for C-H chain breakage, promoting dehydrogenation, hydrogen migration, and C=C protonation of the polyethylene molecular chains. This improves the selectivity of catalytic pyrolysis at lower reaction temperatures, increases the content of hydrocarbons in the C18 range, and enhances economic value. By defining the mass relationship between copper ions and titanium dioxide nanosheets, sufficient active sites are ensured while avoiding excessive loading that could lead to the formation of crystalline Cu.

Description

Technical Field

[0001] This invention belongs to the field of catalytic pyrolysis technology, specifically relating to a Cu / TiO2 composite material, its preparation method, and its application. Background Technology

[0002] Polyolefin plastics are the world's largest and most widely used type of plastic, accounting for about 60% of total plastic production. It is estimated that polyolefin production will reach 500 million tons by 2050.

[0003] Polyethylene is a major polyolefin plastic, and depending on the polymerization conditions and density, it includes high-density polyethylene, low-density polyethylene, and linear low-density polyethylene (LDPE). LDPE's production has been increasing year by year due to its low cost, ease of processing, high ductility, good chemical stability, and durability. It is widely used in industrial production and daily consumer goods, such as films (plastic bags, agricultural mulch films), packaging materials, wire and cable sheaths, injection molded products, and various containers.

[0004] The treatment of LDPE waste plastics mainly includes incineration, landfill, and biodegradation. Statistics show that up to 79% of LDPE plastic waste is landfilled in the natural environment, 12% is incinerated, and only 9% is recycled. Landfilling generates microplastics (~5nm), which are difficult to decompose in nature and accumulate in ecosystems over time, leading to ecological imbalance. Many foods, such as seafood, bottled water, milk, and coffee, contain microplastic particles. Microplastics can also float and settle in water bodies, be ingested by organisms, accumulate in their bodies, affect their growth, reproduction, and survival rates, and enter the food chain, potentially causing diseases of the digestive, cardiovascular, and nervous systems, thus endangering human health. Incineration also produces toxic gas emissions, causing secondary pollution. Even recycled plastics are downgraded and used to create low-value products.

[0005] Chemical recycling methods, such as catalytic conversion, which utilize catalysts to regulate the recovery process, hold promise for the resource recovery and efficient volume reduction of LDPE waste plastics, attracting widespread attention from researchers. Researchers are exploring efficient and selective thermocatalytic conversion of polyolefin waste plastics into high-value-added liquid products under high temperature, solvent, or hydrogen pressure conditions. Among the numerous reported thermocatalytic materials, molecular sieves, with their tunable acidic sites and suitable pore sizes, have garnered significant attention; examples include common commercial catalysts such as HZSM-5, Bate, SAPO-34, HY, and SBA-15. However, existing catalysts all require high temperatures (above 400°C) or hydrogen pressure, and some even require solvent assistance to convert polyethylene waste plastics into high-value-added products. High temperatures increase costs, hydrogen pressure poses an explosion risk, and solvent assistance generates difficult-to-separate byproducts; these issues hinder the high-value utilization of LDPE waste plastics. Summary of the Invention

[0006] The purpose of this invention is to provide a Cu / TiO2 composite material, its preparation method, and its applications. The Cu / TiO2 composite material prepared by the method of this invention can convert LDPE waste plastic into high-value-added liquid hydrocarbons at relatively low temperatures without the need for hydrogen or other additives.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing Cu / TiO2 composite materials, comprising the following steps: The titanium source, P123, acid regulator and ethylene glycol were mixed to obtain a precursor solution; The precursor solution was subjected to a solvothermal reaction to obtain TiO2 nanosheets; The TiO2 nanosheets were mixed with a copper salt solution and then adsorbed to obtain adsorbed TiO2; the mass of copper ions in the copper salt solution was 0.25~0.35% of the mass of the TiO2 nanosheets. The adsorbed TiO2 is reduced to obtain a Cu / TiO2 composite material; the atmosphere of the reduction reaction is a mixture of hydrogen and argon; the temperature of the reduction reaction is 320~380℃.

[0008] Preferably, the mass ratio of the titanium source to P123 is (5~7):1.

[0009] Preferably, the acidity regulator includes nitric acid or hydrochloric acid.

[0010] Preferably, the pH value of the precursor solution is 0.1 to 0.5.

[0011] Preferably, the ratio of the amount of titanium source to ethylene glycol is 1g:(25~45)mL.

[0012] Preferably, the temperature of the solvothermal reaction is 140~160℃ and the time is 16~24h.

[0013] Preferably, the adsorption is carried out under stirring at a speed of 600-1000 r / min; the adsorption time is 10-15 h.

[0014] Preferably, the volume fraction of hydrogen in the hydrogen-argon mixture is 1-3%; and the reduction time is 40-80 min.

[0015] The present invention also provides a Cu / TiO2 composite material prepared by the preparation method described in the above technical solution.

[0016] The present invention also provides the application of the Cu / TiO2 composite material described above in the catalytic pyrolysis of polyethylene waste plastic into liquid hydrocarbons, wherein the catalytic pyrolysis temperature is 340~360℃.

[0017] This invention provides a method for preparing a Cu / TiO2 composite material, comprising the following steps: firstly, mixing a titanium source, P123, an acid modifier, and ethylene glycol to obtain a precursor solution; secondly, subjecting the precursor solution to a solvothermal reaction to obtain TiO2 nanosheets; thirdly, mixing the TiO2 nanosheets with a copper salt solution and then adsorbing the mixture to obtain adsorbed TiO2; wherein the mass of copper ions in the copper salt solution is 0.25~0.35% of the mass of the TiO2 nanosheets; and fourthly, reducing the adsorbed TiO2 to obtain the Cu / TiO2 composite material; wherein the atmosphere for the reduction reaction is a hydrogen-argon mixture; and the temperature for the reduction reaction is 320~380℃. This invention, by defining the template agent and reaction medium, can obtain TiO2 nanosheets with high specific surface area and good catalytic pyrolysis activity. Using TiO2 nanosheets as the main body of the composite material increases the contact with polyethylene molecular chains, causing the polyethylene molecular chains to break. In-situ loading of Cu provides abundant active sites and lowers the energy barrier for CH chain breakage, promoting dehydrogenation, hydrogen migration, and C=C protonation of the polyethylene molecular chains. This improves the selectivity of catalytic pyrolysis at lower reaction temperatures, increases the content of hydrocarbons in the C18 range, and enhances economic value. By defining the mass relationship between copper ions and TiO2 nanosheets, sufficient active sites are ensured while avoiding excessive loading that could form crystalline Cu. The results of the examples show that the Cu / TiO2 composite material prepared by the method provided by this invention can catalytically pyrolyze waste polyethylene into liquid hydrocarbons at 350℃, with a selective liquid hydrocarbon content of 93% in the C18 range. Attached Figure Description

[0018] Figure 1 The XRD patterns are of the materials prepared in Example 1 and Comparative Examples 1-5 of this invention. Figure 2 This is a SEM image of the Cu / TiO2 composite material prepared in Example 1 of the present invention; Figure 3 Here is a SEM image of the two-dimensional TiO2 material prepared in Comparative Example 1 of this invention; Figure 4 This is a SEM image of the Ni / TiO2 composite material prepared in Comparative Example 2 of this invention; Figure 5 This is a SEM image of the Fe / TiO2 composite material prepared in Comparative Example 3 of this invention; Figure 6 This is a SEM image of the Co / TiO2 composite material prepared in Comparative Example 4 of this invention; Figure 7 This is a SEM image of the Ru / TiO2 composite material prepared in Comparative Example 5 of this invention; Figure 8 The carbon number distribution of the Cu / TiO2 composite material obtained in Example 1 of this invention on the catalytic pyrolysis products of pure LDPE is shown in the figure. Figure 9 This is a carbon number distribution diagram of the catalytic pyrolysis products of pure LDPE by the two-dimensional TiO2 material prepared in Comparative Example 1 of this invention. Figure 10 The carbon number distribution of the catalytic pyrolysis products of pure LDPE by the Ni / TiO2 composite material prepared in Comparative Example 2 of this invention is shown. Figure 11 The carbon number distribution of the Fe / TiO2 composite material prepared in Comparative Example 3 of this invention on the catalytic pyrolysis products of pure LDPE is shown in the figure. Figure 12 The carbon number distribution of the catalytic pyrolysis products of pure LDPE by the Co / TiO2 composite material prepared in Comparative Example 4 of this invention is shown. Figure 13 The carbon number distribution of the catalytic pyrolysis products of pure LDPE by the Ru / TiO2 composite material prepared in Comparative Example 5 of this invention is shown. Figure 14 The carbon number distribution of the Cu / TiO2 composite material prepared in Comparative Example 6 of this invention on the catalytic pyrolysis products of pure LDPE is shown in the figure. Figure 15 The carbon number distribution of the Cu / TiO2 composite material prepared in Comparative Example 7 of this invention on the catalytic pyrolysis products of pure LDPE is shown in the figure. Figure 16 The carbon number distribution of the Cu / TiO2 composite material prepared in Comparative Example 8 of this invention on the catalytic pyrolysis products of pure LDPE is shown in the figure. Figure 17 This is a carbon number distribution diagram of the catalytic pyrolysis products of the Cu / TiO2 composite material prepared in Example 1 of the present invention on the mulch film; Figure 18 The carbon number distribution of the catalytic pyrolysis products of the Cu / TiO2 composite material prepared in Example 1 of this invention on the dropper is shown in the figure. Figure 19 This is a carbon number distribution diagram of the catalytic pyrolysis products of LDPE gloves produced by the Cu / TiO2 composite material prepared in Example 1 of this invention. Figure 20 This is a carbon number distribution diagram of the catalytic pyrolysis products of LDPE self-sealing bags prepared by the Cu / TiO2 composite material in Example 1 of the present invention. Figure 21 This is a carbon number distribution diagram of the catalytic pyrolysis products of the Cu / TiO2 composite material obtained in Example 1 of the present invention on a PP plastic cup. Detailed Implementation

[0019] All raw materials used in this invention are not particularly limited in their source; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0020] There are no particular restrictions on the purity of any of the raw materials used in this invention, but industrially pure raw materials are preferred.

[0021] This invention provides a method for preparing Cu / TiO2 composite material, characterized by comprising the following steps: The titanium source, P123, acid regulator and ethylene glycol were mixed to obtain a precursor solution; The precursor solution was subjected to a solvothermal reaction to obtain TiO2 nanosheets; The TiO2 nanosheets were mixed with a copper salt solution for adsorption to obtain adsorbed TiO2; the mass of copper ions in the copper salt solution was 0.25~0.35% of the mass of the TiO2 nanosheets. The adsorbed TiO2 is reduced to obtain a Cu / TiO2 composite material; the reduction atmosphere is a mixture of hydrogen and argon; the reduction temperature is 320~380℃.

[0022] This invention mixes a titanium source, P123, an acid regulator, and ethylene glycol to obtain a precursor solution.

[0023] In one embodiment of the present invention, the titanium source may be isopropyl titanate, n-butyl titanate, titanium tetrachloride, or tetraethyl titanate.

[0024] In this invention, the acid modifier is preferably hydrochloric acid or nitric acid. The acid modifier affects the morphology of the TiO2 nanosheets and promotes stable hydrolysis, further enhancing the catalytic activity of titanium dioxide. In the embodiments of this invention, the hydrochloric acid has a mass concentration of 37%, and 4.3 g of hydrochloric acid is used for every 6 g of titanium source.

[0025] In this invention, the preferred mass ratio of the titanium source to P123 is (5~7):1, more preferably 6:1. P123 is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, which serves as a template agent for preparing TiO2 nanosheets and determines the morphology of titanium dioxide. A mass ratio of titanium source to P123 within the above range is beneficial for further improving the reactivity of the product. In the embodiments of this invention, the molecular weight of P123 is 5800.

[0026] In this invention, the preferred ratio of titanium source to ethylene glycol is 1 g:(25~45) mL, more preferably 1 g:(30~40) mL. As one embodiment of this invention, the ratio of titanium source to ethylene glycol can be 1 g:28 mL, 1 g:32 mL, 1 g:35 mL, 1 g:38 mL, or 1 g:42 mL. Ethylene glycol is a medium for solvothermal reactions and can improve the stability of TiO2 nanosheets. Using ethylene glycol within the above range is beneficial for the solvothermal reaction, controlling the morphology of TiO2 nanosheets, and further improving the catalytic activity of TiO2 nanosheets.

[0027] In this invention, the pH value of the precursor solution is preferably 0.1 to 0.5, more preferably 0.2 to 0.4; as one embodiment of this invention, the pH value of the precursor solution can be 0.15, 0.25, 0.3, 0.32, 0.35, or 0.45. A pH value within the above range is beneficial for the hydrolysis reaction to proceed.

[0028] In one embodiment of the present invention, the first mixing may be as follows: mixing the titanium source with an acidity regulator (third mixing) to obtain solution A; then mixing solution A with P123 (fourth mixing) to obtain a mixed liquid; and finally mixing the mixed liquid with ethylene glycol (fifth mixing) to obtain a precursor solution. The third and fourth mixing can be carried out under stirring conditions, and the stirring time can be independently 10-60 minutes. The present invention does not impose any particular limitation on the stirring parameters, as long as the raw materials are stirred evenly.

[0029] In one embodiment of the present invention, P123 can be added in the form of an ethanol solution of P123; the mass ratio of P123 to anhydrous ethanol is preferably 1:(13~18), more preferably 1:15; the mass ratio of P123 to anhydrous ethanol within the above range is beneficial to the dissolution of P123 and further improves the stability of the hydrolysis reaction.

[0030] As one embodiment of the present invention, the ethanol solution of P123 can be prepared by dissolving P123 in anhydrous ethanol and stirring; the stirring can be magnetic stirring, and the stirring time can be 15~30 min.

[0031] After obtaining the precursor solution, the present invention performs a solvothermal reaction on the precursor solution to obtain TiO2 nanosheets.

[0032] In this invention, the temperature of the solvothermal reaction is preferably 140~160℃, more preferably 145~155℃, and even more preferably 150℃. A solvothermal reaction temperature within the above range is beneficial for obtaining TiO2 nanosheets.

[0033] In this invention, the solvothermal reaction time is preferably 16-24 hours, more preferably 18-22 hours, and even more preferably 20 hours. A solvothermal reaction time within the above range is beneficial for the complete hydrolysis.

[0034] In one embodiment of the present invention, the solvothermal reaction can be carried out in a reaction vessel; after the reaction is completed, the reaction system is naturally cooled to room temperature, the mixture obtained from the reaction is filtered, and the obtained filter cake is washed and dried to obtain TiO2 nanosheets; the washing can be carried out by sequentially using distilled water and anhydrous ethanol; the drying temperature can be 80°C.

[0035] After obtaining TiO2 nanosheets, the present invention mixes the TiO2 nanosheets with a copper salt solution for a second time, and then performs adsorption to obtain adsorbed TiO2.

[0036] In one embodiment of the present invention, the copper salt solution may be an aqueous solution of copper nitrate; the concentration of the copper salt solution may be 1.5~3 mg / mL.

[0037] In this invention, the mass of copper ions in the copper salt solution is 0.25~0.35% of the mass of TiO2 nanosheets, preferably 0.3%. Maintaining the mass relationship between copper ions and TiO2 nanosheets within this range ensures the formation of sufficient active sites while avoiding excessive loading that could lead to the formation of crystalline Cu.

[0038] In one embodiment of the present invention, the second mixing may involve dispersing TiO2 nanosheets in water and then adding a copper salt solution.

[0039] In this invention, the adsorption is preferably carried out under stirring, and the stirring rate is preferably 600-1000 r / min, more preferably 700-900 r / min; as one embodiment of this invention, the stirring rate can be 600 r / min, 700 r / min, 800 r / min, 900 r / min, or 1000 r / min. A stirring rate within the above range is beneficial for the adsorption of copper ions by TiO2 nanosheets.

[0040] In this invention, the adsorption time is preferably 10-15 hours, more preferably 11-13 hours; as one embodiment of this invention, the adsorption time can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, or 15 hours. An adsorption time within the above range is beneficial for the adsorption of copper ions by TiO2 nanosheets.

[0041] In one embodiment of the present invention, after adsorption, the product can be collected by filtration, and then washed to obtain adsorbed TiO2. The present invention does not particularly limit the specific operations of filtration and washing; conventional operations in the art can be used.

[0042] After obtaining the adsorbed TiO2, the present invention performs a reduction reaction on the adsorbed TiO2 to obtain a Cu / TiO2 composite material.

[0043] In this invention, the atmosphere for the reduction reaction is a mixture of hydrogen and argon, wherein the volume fraction of hydrogen in the hydrogen-argon mixture is preferably 1-3%, more preferably 2%. Using a hydrogen-argon mixture as a reducing atmosphere ensures uniform heating of the adsorbed TiO2, facilitating a stable reduction reaction. A hydrogen volume fraction within the above range is beneficial for the reduction and dispersion of copper, further enhancing the catalytic activity of the product.

[0044] In this invention, the temperature of the reduction reaction is 320~380℃, preferably 340~360℃; as one embodiment of this invention, the temperature of the reduction reaction can be 330℃, 340℃, 350℃, 360℃, or 370℃. Within the above temperature range, copper ions can be reduced to elemental copper while avoiding the reduction of titanium dioxide.

[0045] This invention, by defining the template agent and reaction medium, can obtain TiO2 nanosheets with high specific surface area and good catalytic pyrolysis activity. Using TiO2 nanosheets as the main body of the composite material increases the contact with polyethylene molecular chains, causing the polyethylene molecular chains to break. By in-situ loading Cu, abundant active sites are provided, and the energy barrier for CH chain breakage is lowered, promoting the dehydrogenation, hydrogen migration, and C=C protonation of polyethylene molecular chains. This improves the selectivity of catalytic pyrolysis at lower reaction temperatures, increases the content of hydrocarbons in the C18 range, and enhances economic value. By defining the mass relationship between copper ions and TiO2 nanosheets, sufficient active sites are ensured, while avoiding excessive loading that could lead to the formation of crystalline Cu.

[0046] The present invention also provides a Cu / TiO2 composite material prepared by the preparation method described in the above technical solution.

[0047] In one embodiment of the present invention, the total acid content of the Cu / TiO2 composite material can be 19~20 μmol / g, and the specific surface area can be 200~220 m². 2 g -1 At 350℃, the L / B acid ratio can be 5.9~6.15.

[0048] The Cu / TiO2 composite material provided by this invention can convert LDPE waste plastic into high-value-added liquid hydrocarbons at a lower temperature without the need for hydrogen or other additives.

[0049] The present invention also provides the application of the Cu / TiO2 composite material described above in the catalytic pyrolysis of polyethylene waste plastics into liquid hydrocarbons.

[0050] In this invention, the catalytic pyrolysis temperature is 340~360℃, preferably 350℃. The Cu / TiO2 composite material provided by this invention can catalytically pyrolyze polyethylene waste plastic into liquid hydrocarbons at a lower temperature, and does not require the use of auxiliary agents such as hydrogen, thus exhibiting higher economic efficiency.

[0051] As one embodiment of the present invention, the catalytic pyrolysis method can be as follows: the Cu / TiO2 composite material and LDPE waste plastic are added to a high-temperature and high-pressure reactor at a mass ratio of 1:5. After the filling is completed, nitrogen is used for purging, and catalytic pyrolysis is carried out by heating in a nitrogen atmosphere. The heating rate of the catalytic pyrolysis can be 5℃ / min. The catalytic pyrolysis time can be 10~15h or 12h.

[0052] In one embodiment of the present invention, the polyethylene can be linear low-density polyethylene, specifically mulch film, drip irrigation device, LDPE gloves, LDPE self-sealing bag and PP plastic cup.

[0053] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0054] Example 1 A method for preparing a Cu / TiO2 composite material, the specific steps of which are as follows: Add 6g of isopropyl titanate to 4.3g of concentrated hydrochloric acid (37%) solution and stir for 10min to obtain solution A; Dissolve 1g of P123 in 15g of anhydrous ethanol and stir magnetically for 30min to obtain solution B; Solution B was added to solution A and stirred for 60 minutes to obtain a mixture. Then, the mixture was mixed with ethylene glycol at a volume ratio of 1:8 and transferred to a reaction vessel. The mixture was kept at 150°C for 20 hours to carry out a solvothermal reaction. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was washed with distilled water and anhydrous ethanol. It was then dried at 80°C, and the white powder was collected, which is TiO2 nanosheets. 100 mg TiO2 nanosheets were dispersed in 100 mL of deionized water, and 0.5 mL of Cu(NO3)2·3H2O aqueous solution (2.28 mg / mL) was added. The mixture was adsorbed for 12 h under vigorous stirring at 1000 r / min, then filtered and washed. The mixture was then reduced at 350 °C for 1 h in a 2% H2 / Ar reducing atmosphere to obtain Cu / TiO2 composite material.

[0055] The total acid content of the prepared Cu / TiO2 composite material was 19.33 μmol / g (measured by pyridine infrared spectroscopy, Py-IR), and the specific surface area of ​​the Cu / TiO2 composite material was 211 m². 2 g -1 The L / B acid ratio at 350℃ is 6.04 (measured by Py-IR spectroscopy).

[0056] Comparative Example 1 A method for preparing two-dimensional TiO2 materials is the same as the method for preparing TiO2 nanosheets in Example 1.

[0057] The total acid content of the prepared two-dimensional TiO2 material was 15.64 μmol / g (measured by pyridine infrared spectroscopy, Py-IR), and the specific surface area of ​​the Cu / TiO2 composite material was 364.7 m². 2 g -1 The L / B acid ratio at 350℃ is 7.51 (measured by Py-IR spectroscopy).

[0058] Comparative Example 2 A method for preparing a Ni / TiO2 composite material, the specific steps are the same as in Example 1, except that a Ni(NO3)2·6H2O aqueous solution with a concentration of 2.97 mg / mL is used instead of a Cu(NO3)2·3H2O aqueous solution.

[0059] Comparative Example 3 A method for preparing Fe / TiO2 composite material, the specific steps are the same as in Example 1, except that a Fe(NO3)3·9H2O aqueous solution with a concentration of 4.30 mg / mL is used instead of a Cu(NO3)2·3H2O aqueous solution.

[0060] Comparative Example 4 A method for preparing a Co / TiO2 composite material, the specific steps are the same as in Example 1, except that a Co(NO3)2·6H2O aqueous solution with a concentration of 2.98 mg / mL is used instead of a Cu(NO3)2·3H2O aqueous solution.

[0061] Comparative Example 5 A method for preparing Ru / TiO2 composite material, the specific steps are the same as in Example 1, except that a RuCl3·3H2O aqueous solution with a concentration of 1.23 mg / mL is used instead of a Cu(NO3)2·3H2O aqueous solution.

[0062] Comparative Example 6 A method for preparing Cu / TiO2 composite material, the specific steps are the same as in Example 1, except that the concentration of Cu(NO3)2·3H2O aqueous solution is 0.76 mg / mL.

[0063] The total acid content of the prepared Cu / TiO2 composite material was 17.42 μmol / g (measured by pyridine infrared spectroscopy, Py-IR), and the specific surface area of ​​the Cu / TiO2 composite material was 216 m². 2 g -1 The L / B acid ratio at 350℃ is 6.22 (measured by Py-IR spectroscopy).

[0064] Comparative Example 7 A method for preparing Cu / TiO2 composite material, the specific steps are the same as in Example 1, except that the concentration of Cu(NO3)2·3H2O aqueous solution is 3.80 mg / mL.

[0065] The total acid content of the prepared Cu / TiO2 composite material was 16.51 μmol / g (measured by pyridine infrared spectroscopy, Py-IR), and the specific surface area of ​​the Cu / TiO2 composite material was 207 m². 2 g -1 The L / B acid ratio at 350℃ is 6.87 (measured by Py-IR spectroscopy).

[0066] Comparative Example 8 A method for preparing Cu / TiO2 composite material, the specific steps are the same as in Example 1, except that template agent F127 (polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer) is used instead of P123.

[0067] Test Example 1 The materials prepared in Example 1 and Comparative Examples 1-5 were tested using an X-ray diffractometer, and XRD patterns were obtained, as shown below. Figure 1 As shown.

[0068] from Figure 1It can be seen that the composite materials prepared in Example 1 and Comparative Examples 2-5 have the same diffraction peaks as the two-dimensional TiO2 prepared in Comparative Example 1, indicating that the supported metal species are in an amorphous state and have not agglomerated into particles.

[0069] Test Example 2 The materials prepared in Example 1 and Comparative Examples 1-5 were observed using a scanning electron microscope, and SEM images were obtained, as shown below. Figures 2-7 As shown.

[0070] from Figure 3 It can be seen that the two-dimensional TiO2 is a clustered thin film; from Figure 2 It can be seen that after loading Cu species, the morphology is still a stacked thin layer with no obvious change; Figures 4-7 It is also a stack of thin layers.

[0071] Application Example 1 Catalytic pyrolysis of LDPE waste plastic particles was carried out using the materials prepared in Example 1 and Comparative Examples 1-8 as catalysts: 1g of catalyst and 5g of commercially produced pure LDPE particles (commercially available product, used in Taobao commercial applications, by a fashion home furnishing manufacturer) were placed in a high-temperature and high-pressure reactor. Air was purged with nitrogen, and the temperature was increased to 350°C at a stirring rate of 300r / min and a heating rate of 5°C / min, and the reaction was carried out for 12h. The liquid product from the reaction was dissolved in n-hexane, and the type and carbon number distribution of hydrocarbons in the product were determined using GC-MS (Shimadzu). The results are as follows: Figures 8-16 As shown.

[0072] from Figures 8-16 It can be seen that the liquid products after catalytic pyrolysis of LDPE include alkanes, alkenes and aromatics, with carbon numbers ranging from C7 to C30 (a small amount of hydrocarbons with fewer than C7 are collected in gaseous form; the gaseous products were not analyzed in this invention; LDPE is almost completely converted after catalytic pyrolysis, so the conversion rate was not statistically analyzed in this invention).

[0073] contrast Figures 8-13 It can be seen that the Cu / TiO2 composite material prepared in Example 1 has the highest selectivity for hydrocarbons in the C18 range, with a selective liquid hydrocarbon content of 93% in the C18 range (based on all products of catalytic pyrolysis being 100%). The selective liquid hydrocarbon content in the C18 range of the materials prepared in Comparative Examples 1 to 5 is 52%, 67%, 65%, 69%, and 62%, respectively.

[0074] contrast Figure 8 and Figure 14 , Figure 15 It can be seen that the selective liquid hydrocarbon content in the C18 range of the materials prepared in Comparative Examples 6 and 7 is 74% and 82% respectively, which is significantly lower than that in Example 1.

[0075] contrast Figure 8 and Figure 16 It can be seen that the selective liquid hydrocarbon content in the C18 range of the material prepared in Comparative Example 8 is 37%; since there are 50% waxy products after catalytic pyrolysis, it indicates that the material prepared in Comparative Example 8 has a poor catalytic pyrolysis effect on LDPE at 350℃.

[0076] Application Example 2 The Cu / TiO2 composite material prepared in Example 1 was used as a catalyst for the catalytic pyrolysis of mulch film, drip irrigation tubes, LDPE gloves, LDPE self-sealing bags, and PP plastic cups. The parameters were the same as in Application Example 1, and the analysis results of the reaction products are as follows: Figures 17-21 As shown.

[0077] from Figures 17-21 It can be seen that the Cu / TiO2 composite material prepared in Example 1 catalytically pyrolyzes mulch film, drip irrigation tubes, LDPE gloves, LDPE self-sealing bags and PP plastic cups. The selective liquid hydrocarbon content in the C18 range is 92%, 94%, 87%, 90% and 92% respectively, which is close to that of pure LDPE plastic particles.

[0078] As can be seen from the above embodiments, the Cu / TiO2 composite material prepared by the present invention can convert LDPE waste plastic into liquid hydrocarbons at 350℃. The hydrocarbon content is high in the C18 range and has good economic value.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a Cu / TiO2 composite material, characterized in that, Includes the following steps: The titanium source, P123, acid regulator and ethylene glycol were mixed to obtain a precursor solution; The precursor solution was subjected to a solvothermal reaction to obtain TiO2 nanosheets; The TiO2 nanosheets were mixed with a copper salt solution for adsorption to obtain adsorbed TiO2; the mass of copper ions in the copper salt solution was 0.25~0.35% of the mass of the TiO2 nanosheets. The adsorbed TiO2 is reduced to obtain a Cu / TiO2 composite material; the reduction atmosphere is a mixture of hydrogen and argon; the reduction temperature is 320~380℃.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the titanium source to P123 is (5~7):

1.

3. The preparation method according to claim 1, characterized in that, The acid regulator includes nitric acid or hydrochloric acid.

4. The preparation method according to claim 1 or 3, characterized in that, The pH value of the precursor solution is 0.1~0.

5.

5. The preparation method according to claim 1, characterized in that, The ratio of the amount of titanium source to ethylene glycol is 1g:(25~45)mL.

6. The preparation method according to claim 1, characterized in that, The solvothermal reaction is carried out at a temperature of 140~160℃ for a time of 16~24h.

7. The preparation method according to claim 1, characterized in that, The adsorption is carried out under stirring at a speed of 600-1000 r / min; the adsorption time is 10-15 h.

8. The preparation method according to claim 1, characterized in that, The volume fraction of hydrogen in the hydrogen-argon mixture is 1-3%; the reduction time is 40-80 min.

9. The Cu / TiO2 composite material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the Cu / TiO2 composite material according to claim 9 or the Cu / TiO2 composite material prepared by the preparation method according to any one of claims 1 to 8 in the catalytic pyrolysis of polyethylene waste plastics into liquid hydrocarbons, characterized in that, The temperature of the catalytic pyrolysis is 340~360℃.

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