Multi-construction layered metal oxide and application thereof in hydro-conversion of polystyrene waste plastic pyrolytic oil

Abstract

According to the multi-construction layered metal oxide and the application thereof in hydro-conversion of the polystyrene waste plastic pyrolytic oil, the prepared multi-construction layered metal oxide serves as a catalyst and is fully mixed with the polystyrene waste plastic pyrolytic oil after being pretreated, and then the mixture is transferred into a reaction kettle; after sealing, filling hydrogen into the reaction kettle, controlling the reaction temperature to be 90-100 DEG C, and stirring to react for 6-12 hours; according to the invention, the multi-constructed NixAl-LDO is combined with the hydrogenation process, and the styrene conversion rate and ethylbenzene selectivity are improved by utilizing the combined action of the structural advantage of the multi-layer catalyst and the hydrogenation reaction.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of polystyrene waste plastic pyrolysis oil hydrogenation, and particularly relates to a multi-constructed layered metal oxide and application thereof as a catalyst for efficiently hydrogenating styrene in polystyrene waste plastic pyrolysis oil into ethylbenzene. BACKGROUND

[0002] Polystyrene (PS) is one of the five general-purpose plastics and is widely used in packaging, cushioning, food containers and building materials due to its excellent performance. However, its characteristics of high chemical stability and difficulty in natural degradation have led to a serious "white pollution" problem caused by a large amount of waste PS. The current mainstream disposal methods such as landfill and incineration have significant drawbacks: landfill occupies a large amount of land resources and shortens the service life of the landfill; incineration may release harmful substances such as NOx, SOx, COx and even carcinogenic polycyclic aromatic hydrocarbons, causing secondary environmental pollution and public health risks. These traditional disposal methods do not meet the sustainable development concept of green circular economy.

[0003] Under this background, chemical recycling methods, especially pyrolysis technology, are considered as the most promising way to deal with waste polystyrene. This technology can convert waste PS into pyrolysis oil by breaking the long polymer chain under high temperature and oxygen-free or limited oxygen conditions, realizing the transformation of waste into treasure. However, there is a core bottleneck in the direct utilization of polystyrene pyrolysis oil: the main component styrene monomer is extremely active in chemical properties and can easily self-polymerize during storage and transportation, leading to increased oil viscosity, deteriorated quality, and equipment and pipeline blockage, which greatly limits its high-value application.

[0004] In order to improve the stability and value of pyrolysis oil, selective hydrogenation is an ideal upgrading route. The goal is to convert unstable styrene into ethylbenzene which has stable properties and high market value. However, there are serious challenges in achieving this goal: when traditional hydrogenation catalysts (such as noble metal or ordinary non-noble metal catalysts) act on styrene, the reaction easily breaks through the ethylene group hydrogenation stage and further saturates the benzene ring to generate ethylcyclohexane and other low-value completely hydrogenated products. This not only increases hydrogen consumption, but also destroys the aromaticity of the target product and reduces the economy of the whole process; existing technologies usually require high reaction temperatures, which not only consumes high energy, but also may exacerbate catalyst coking and deactivation and side reactions. In addition, many high-performance catalytic systems rely on noble metals such as platinum and palladium, whose high cost restricts the application of this technology in large-scale industrial waste plastic treatment; pyrolysis oil has complex components and may contain heteroatom impurities and coke precursors, which easily lead to poisoning or coking of conventional catalysts, affecting their long-term operation stability and service life.

[0005] Therefore, developing a novel, efficient, and highly selective non-precious metal hydrogenation catalyst and a matching mild process that can accurately convert styrene in polystyrene pyrolysis oil into ethylbenzene, while effectively suppressing excessive hydrogenation and polymerization side reactions and possessing good anti-impurity capabilities, has become the key to promoting the chemical recycling technology of polystyrene waste plastics from the laboratory to industrial application, and is also a gap that urgently needs to be filled in this field. Summary of the Invention

[0006] This application provides a multi-layered metal oxide (Ni) x Al-LDO and its application in the highly selective hydrogenation conversion of styrene in polystyrene waste plastic pyrolysis oil, through the multi-constructed Ni x By combining Al-LDO with hydrogenation processes, the structural advantages of multilayer catalysts and the combined effect of hydrogenation reactions can be used to improve styrene conversion and ethylbenzene selectivity.

[0007] A method for preparing a multilayered metal oxide, comprising: (1) Under constant temperature conditions of 30-40℃, the mixture containing Ni 2+ And Al 3+ A mixed aqueous solution of nitrates was added dropwise to an aqueous solution of sodium carbonate, with continuous stirring during the addition and the pH of the reaction system maintained at 10.0 ± 0.3. After the addition was complete, the reaction was stirred for 6-12 hours to obtain a mixed solution. The resulting mixed solution was allowed to stand at room temperature for 10-12 hours, washed until neutral, dried, and then ground to obtain a monolayer Ni. x Al LDH intermediate product; (2) Take all the obtained monolayer Ni x The Al LDH intermediate was redispersed in the same sodium carbonate aqueous solution as in step (1); then, the same nitrate mixed aqueous solution as in step (1) was added dropwise to the sodium carbonate aqueous solution; the dropwise addition was performed as in step (1), and the resulting mixture was treated in the same way as in step (1) to obtain a bilayer Ni. x Al LDH intermediate product; (3) Regarding the obtained bilayer Ni x Al LDH intermediate, repeat step (2) until n layers of Ni are obtained. x AlLDH intermediate product; (4) The obtained n-layer Ni x The multilayered metal oxide is obtained by calcining and activating the Al LDH intermediate.

[0008] Several alternative methods are provided below, but they are not intended as additional limitations on the overall solution above. They are merely further additions or optimizations. Provided there are no technical or logical contradictions, each alternative method can be combined individually with respect to the overall solution above, or multiple alternative methods can be combined with each other.

[0009] Ni x In Al LDH, x represents the Ni content in the nitrate mixed aqueous solution. 2+ And Al 3+ The molar ratio, optionally, is that of Ni in the nitrate mixed aqueous solution. 2+ And Al 3+ The molar ratio is 1~2:1; the mixing ratio of the sodium carbonate aqueous solution and the nitrate mixed aqueous solution is based on the ratio of sodium carbonate to Ni. 2+ The molar ratio is 1:1.

[0010] Optionally, the Ni in the nitrate mixed aqueous solution 2+ The concentration is 0.2~0.4 M, Al 3+ The concentration of the nitrate mixed aqueous solution is 0.1~0.2M; the concentration of the sodium carbonate aqueous solution is 0.1~0.2M; the volume ratio of the nitrate mixed aqueous solution to the sodium carbonate aqueous solution is based on the ratio of sodium carbonate to Ni... 2+ The molar ratio is 1:1.

[0011] Furthermore, the Ni in the nitrate mixed aqueous solution 2+ The concentration was 0.4 M, Al 3+ The concentration of the sodium carbonate solution is 0.2 M; the concentration of the sodium carbonate aqueous solution is 0.2 M; the volume ratio of the nitrate mixed aqueous solution to the sodium carbonate aqueous solution is 1:2.

[0012] Optionally, n is 3 to 5.

[0013] Furthermore, the Ni in the nitrate mixed aqueous solution 2+ And Al 3+ The molar ratio is 1:1, 1.5:1 or 2:1; the most preferred ratio is 2:1, and n is 3.

[0014] Optionally, the dropping rate is 3-5 mL / min.

[0015] Furthermore, 50 mL of a mixed aqueous solution of nitrates containing 0.01-0.02 mol Ni(NO3)2·6H2O and 0.05-0.01 mol Al(NO3)3·9H2O is slowly added dropwise to 100 mL of an aqueous solution of sodium carbonate with a concentration of 0.01-0.02 mol at a rate of 3-5 mL / min.

[0016] Optional, the stirring speed is 800~1200 rpm.

[0017] Optionally, the pH of the mixture can be maintained by adding 1-2 mol / L NaOH solution during the dropwise addition process.

[0018] Optional, after grinding, pass through an 80-mesh sieve.

[0019] The “sodium carbonate aqueous solution that is the same as that in step (1)” mentioned in step (2) means that the concentration and volume of the sodium carbonate aqueous solution are the same as those in step (1); similarly, the “nitrate mixed aqueous solution that is the same as that in step (1)” means that the composition, concentration and volume of the nitrate mixed aqueous solution are the same as those in step (1).

[0020] Optionally, the calcination activation temperature in step (3) is 400~500℃ and the time is 4~6 hours.

[0021] This application also provides a multilayered metal oxide prepared by the aforementioned preparation method.

[0022] In this catalyst, Ni 2+ Ions are the main redox active centers, endowing the catalyst with excellent hydrogenation activity; Al 3+ The ions primarily function to stabilize the layered structure and enhance thermal stability. This multilayered Ni... x Al-LDO has a high specific surface area and abundant surface acid and base sites. At the same time, calcination produces highly dispersed active components, a multi-element metal coordination environment, and a large number of surface defects. These characteristics together enhance the adsorption and activation of styrene molecules, thus enabling it to have excellent styrene hydrogenation conversion ability under mild conditions.

[0023] This application also provides an application of the reconstituted layered metal oxide in the hydrogenation of styrene to ethylbenzene in polystyrene waste plastic pyrolysis oil.

[0024] This application also provides a method for hydrogenating styrene into ethylbenzene from polystyrene waste plastic pyrolysis oil, including: The multilayered metal oxide was used as a catalyst and pretreated before being thoroughly mixed with polystyrene waste plastic pyrolysis oil. The mixture was then transferred to a reactor, sealed, and hydrogen was introduced into the reactor. The reaction temperature was controlled at 95~105℃, and the reaction was stirred for 6~12 hours.

[0025] Optionally, the styrene content in the polystyrene waste plastic pyrolysis oil is 40-50% by mass; the amount of catalyst used is 0.25-1% of the mass of the polystyrene waste plastic pyrolysis oil.

[0026] Furthermore, the amount of catalyst used is 0.25~0.5% of the mass of polystyrene waste plastic pyrolysis oil; even further, the amount of catalyst used is 0.25% of the mass of polystyrene waste plastic pyrolysis oil.

[0027] Optionally, the catalyst pretreatment is as follows: the catalyst needs to undergo reduction treatment, heated to 450°C at 5°C / min in 10% H2 / Ar and held for 2 hours, and then used after cooling.

[0028] Optionally, the amount of hydrogen introduced is such that the hydrogen pressure inside the reactor is 3-5 MPa.

[0029] Optionally, the reaction temperature is 100°C.

[0030] The polystyrene waste plastic pyrolysis oil contains toluene (typically 1-3 μg / mL). The catalyst in this application has been verified to not interfere with the conversion of styrene to ethylbenzene; the toluene concentration remains essentially unchanged before and after the reaction. This demonstrates that the catalyst selectively activates only the vinyl double bonds of styrene and has no catalytic effect on saturated groups or stable benzene rings. Besides toluene, the pyrolysis oil also contains impurities such as polycyclic aromatic hydrocarbons, heteroatoms, and oligomers, but none of these have caused poisoning or coking deactivation of the catalyst in this application, proving that the catalyst has good resistance to impurities.

[0031] Compared with the prior art, this application has at least one of the following beneficial effects: (1) Directed conversion capability: Under the conditions of 100℃, 3-5MPa H2, and 600rpm, when treating PS pyrolysis oil containing 40%-50% styrene for 12 hours, the selectivity of commercial Pt / C catalysts for ethylbenzene is only 78%, while the multiple Ni-constructed catalysts of this invention achieve a higher selectivity. x Al-LDO catalysts can achieve 100% styrene conversion and 100% ethylbenzene selectivity.

[0032] (2) Multiple structures result in ultra-high exposure of active sites: The ordered stacked multilayer structure formed by the "multi-layer construction" process increases the specific surface area of ​​the catalyst by more than 40% compared with the single-layer structure, Ni² + Increased exposure of active sites significantly enhances the adsorption and activation capacity of styrene molecules, laying the structural foundation for low-temperature and efficient hydrogenation.

[0033] (3) Excellent overall performance of the catalyst: The Ni catalyst with multiple components has excellent overall performance. x Al-LDO catalysts not only have the advantages of high specific surface area and abundant acid-base sites, but also form highly dispersed active centers through calcination, which promotes the capture of styrene molecules.

[0034] (4) The catalyst of this application can accurately convert styrene in polystyrene pyrolysis oil into ethylbenzene, while effectively inhibiting excessive hydrogenation and polymerization side reactions, and has good anti-impurity ability. Attached Figure Description

[0035] Figure 1 Results of hydrogenation of polystyrene pyrolysis oil under NiAl-LDO catalysis with different Ni / Al molar ratios for multiple constructions ((a) concentration of BTX (monocyclic aromatic hydrocarbons); (b) pressure drop of H2; (c) conversion of styrene; (d) selectivity of ethylbenzene).

[0036] Figure 2 The results of hydrogenation of polystyrene pyrolysis oil under different dosages of the multi-component Ni2Al-LDO catalyst are shown in the figures (a) concentration of BTX; (b) pressure drop of H2; (c) conversion of styrene; and (d) selectivity of ethylbenzene.

[0037] Figure 3 This is a comparison of the mass spectra obtained in Example 2 with and without a catalyst.

[0038] Figure 4 The images show the detection results for Comparative Examples 1 to 3. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0041] The preparation of the catalyst includes: Base layer construction: Under constant temperature of 30-40℃, 40-60 mL of a mixed aqueous solution of nitrates containing 0.01-0.02 mol Ni(NO3)2·6H2O and 0.05-0.01 mol Al(NO3)3·9H2O is slowly added dropwise at a rate of 3-5 mL / min to 80-120 mL of an aqueous solution of 0.01-0.02 mol sodium carbonate. During the addition, the mixture is continuously stirred at 800-1200 rpm, and the pH of the mixture is maintained at 10.0±0.3 by adding 1~2 mol / L NaOH solution. After the addition is completed, the mixture is stirred for 6-12 hours to obtain the final mixture.

[0042] The resulting mixture was allowed to stand at room temperature for 10-12 hours, filtered, and the filter cake was washed with deionized water until the pH of the filtrate was 7. After drying, it was ground and passed through an 80-mesh sieve to obtain a monolayer Ni. x Al LDH intermediate.

[0043] Second layer construction: The resulting monolayer Ni x Al LDH was re-dispersed ultrasonically into 80-120 mL of a 0.01-0.02 mol sodium carbonate aqueous solution. Then, 40-60 mL of a nitrate aqueous solution containing 0.01-0.02 mol Ni(NO3)2·6H2O and 0.05-0.01 mol Al(NO3)3·9H2O was slowly added dropwise to the mixed solution at a rate of 3-5 mL / min. During the addition, the mixture was continuously stirred at 800-1200 rpm, and the pH of the mixture was maintained at 10.0±0.3 by adding 1-2 mol / L NaOH solution. After the addition was completed, the mixture was stirred for 6-12 hours to obtain the final mixture.

[0044] The resulting mixture was allowed to stand at room temperature for 10-12 hours, filtered, and the filter cake was washed with deionized water until the pH of the filtrate was 7. After drying, it was ground and passed through an 80-mesh sieve to obtain a double-layer Ni. x Al LDH intermediate.

[0045] Repeat the second layer construction steps up to the nth layer construction: The resulting n-1 layers of Ni xAl LDH was re-dispersed ultrasonically into 80-120 mL of a 0.01-0.02 mol sodium carbonate aqueous solution. Then, 40-60 mL of a nitrate aqueous solution containing 0.01-0.02 mol Ni(NO3)2·6H2O and 0.05-0.01 mol Al(NO3)3·9H2O was slowly added dropwise to the mixed solution at a rate of 3-5 mL / min. During the addition, the mixture was continuously stirred at 800-1200 rpm, and the pH of the mixture was maintained at 10.0±0.3 by adding 1-2 mol / L NaOH solution. After the addition was completed, the mixture was stirred for 6-12 hours to obtain the final mixture.

[0046] The resulting mixture was allowed to stand at room temperature for 10-12 hours, filtered, and the filter cake was washed with deionized water until the pH of the filtrate was 7. After drying, it was ground through an 80-mesh sieve to obtain n-layer Ni. x Al LDH intermediate.

[0047] Calcination and activation: Put n layers of Ni x Al LDH was placed in a muffle furnace and calcined at 400-500℃ for 4-6 hours, followed by natural cooling to obtain multiple Ni. x Al-LDO catalyst.

[0048] The following is a description using specific embodiments: The preparation process of the pyrolysis oil used in the following examples is as follows: Take 200 g of general-purpose polystyrene (GPPS) plastic and place it in a quartz reaction tube. Purge nitrogen gas at a rate of 30 mL / min as an inert atmosphere. Program the temperature up to 400 ℃ at a rate of 20 ℃ / min and hold it at a constant temperature for 60 min to allow GPPS to fully pyrolyze. After the gaseous pyrolysis product is cooled by a condensation system, the liquid product is collected as pyrolysis oil.

[0049] Example 1 Preparation and application of monolayer Ni2Al-LDO catalyst (reaction conditions: 100ml reactor, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0050] (1) Construction of the base layer (initial co-precipitation): 0.02 mol Ni(NO3)2·6H2O and 0.01 mol Al(NO3)3·9H2O were dissolved in 50 mL of deionized water and stirred for 1 h until completely dissolved to obtain a nitrate mixed solution; 0.02 mol sodium carbonate was dissolved in 100 mL of deionized water and stirred for 1 h until completely dissolved to obtain a sodium carbonate aqueous solution. 50 mL of nitrate mixture was slowly added dropwise to 100 mL of sodium carbonate aqueous solution at a rate of 1 mL / min. During the addition, the mixture was continuously stirred at 1000 rpm, and the pH of the mixture was maintained at 10.0 ± 0.3 by adding 2 mol / L NaOH solution. After the addition was completed, the mixture was stirred for 6.5 hours to obtain the final mixture. The resulting mixture was allowed to stand at room temperature for 12 hours, filtered, and the filter cake was washed 10 times with deionized water until the pH of the filtrate was 7. It was then dried at 60°C for 24 hours and ground through an 80-mesh sieve to obtain a monolayer Ni2Al LDH intermediate product.

[0051] (2) Calcination activation: Monolayer Ni2Al LDH was placed in a muffle furnace and calcined at 400℃ for 5 hours. After natural cooling, a monolayer Ni2Al-LDO catalyst was obtained.

[0052] (3) Catalyst performance evaluation Catalyst pretreatment: The catalyst needs to undergo reduction treatment by heating to 450°C at 5°C / min in 10% H2 / Ar and holding for 2 hours. It can be used after cooling.

[0053] Take 0.1g of the pretreated catalyst and add it to 20g of pyrolysis oil. Sonicate for 45min until fully mixed. After thorough mixing, add the mixture to a 100ml reactor, seal it, and purge with H2 to a pressure of 5MPa. React at 100℃ and 600rpm for 12 hours. Use the reaction without catalyst as a blank control.

[0054] After the reaction was completed, samples were taken and analyzed by gas chromatography-mass spectrometry (GC-MS). The concentration of styrene in the system was approximately 16.5 μg / mL, and the concentration of ethylbenzene was approximately 23.1 μg / mL. The styrene conversion rate was 66%, and the ethylbenzene selectivity was 72%. At the same time, the pressure drop of H2 was monitored by a pressure gauge, which showed that it was approximately 1.2 MPa.

[0055] Example 2 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 100ml reactor, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0056] (1) Same as step (1) in Example 1, prepare a monolayer Ni2Al LDH intermediate product.

[0057] (2) The obtained monolayer Ni2Al LDH intermediate was sonicated for 30 min and fully dispersed in 100 mL of sodium carbonate aqueous solution (0.02 mol sodium carbonate dissolved in 100 mL of deionized water and stirred for 1 h until completely dissolved); Then, 50 mL of a nitrate mixture (0.02 mol Ni(NO3)2·6H2O and 0.01 mol Al(NO3)3·9H2O dissolved in 50 mL of deionized water and stirred for 1 h until completely dissolved) was slowly added dropwise at a rate of 1 mL / min to the above sodium carbonate aqueous solution containing a monolayer of Ni2Al LDH. During the dropwise addition, the mixture was continuously stirred at 1000 rpm, while the pH of the mixture was maintained at 10.0 ± 0.3 by adding 2 mol / L NaOH solution dropwise. After the addition was completed, the mixture was stirred for another 6.5 hours to obtain the final mixture. The resulting mixture was allowed to stand at room temperature for 12 hours, filtered, and the filter cake was washed 10 times with deionized water until the pH of the filtrate was 7. It was then dried at 60°C for 24 hours and ground through an 80-mesh sieve to obtain a double-layer Ni2Al LDH intermediate product.

[0058] (3) Repeat step (2) on the obtained bilayer Ni2Al LDH intermediate to obtain a trilayer Ni2Al LDH intermediate.

[0059] (4) Calcination activation: The obtained three-layer Ni2Al LDH intermediate product was calcined at 400℃ for 5 hours to obtain a multi-layered Ni2Al-LDO catalyst.

[0060] (5) Catalyst performance evaluation The evaluation process is the same as in Example 1.

[0061] The results are as follows Figure 1 As shown, the test results indicate that the styrene concentration in the system is close to 0, the ethylbenzene concentration is approximately 42.3 μg / mL, and the toluene content remains essentially unchanged. Figure 1 (a)); styrene conversion rate 100% ( Figure 1 (c) ), ethylbenzene selectivity 87% ( Figure 1 In the middle (d), the H2 pressure drop was approximately 2.3 MPa. Figure 1 (b)

[0062] A comparison of mass spectra obtained with and without catalyst for the Ni2Al-LDO catalyst prepared in this embodiment is shown below. Figure 3 As shown, the baseline of the red spectrum in the figure is consistent with the baseline of the black spectrum. For easier comparison, the red spectrum has been moved upwards as a whole in the figure.

[0063] The typical product of excessive hydrogenation is the further hydrogenation of ethylbenzene to produce ethylcyclohexane, but from... Figure 3 Observations show that in the red spectrum after catalyst addition, a strong ethylbenzene characteristic peak appears only around 10 minutes, while the characteristic chromatographic peak of ethylcyclohexane is not observed (its retention time is usually significantly different from that of ethylbenzene, and there is no corresponding peak in the spectrum); at the same time, the styrene peak has basically disappeared (indicating that styrene has been converted). This indicates that the catalyst in this application selectively hydrogenates styrene to ethylbenzene without triggering excessive hydrogenation side reactions.

[0064] Styrene readily undergoes self-polymerization / thermal polymerization, generating polycyclic aromatic hydrocarbon (PAH) byproducts (corresponding to the PAH region around 30 minutes in the figure). Without a catalyst (black spectrum): this region shows distinct PAH characteristic peaks, indicating styrene polymerization products; while with a catalyst (red spectrum): the peak intensity in this region decreases significantly (almost to the baseline). This directly demonstrates that the catalyst of this application effectively suppresses the polymerization side reactions of styrene, avoiding the formation of PAH byproducts. Through the Figure 3 Observations revealed that the intensity and position of the toluene peak did not change significantly with or without the catalyst, indicating that the catalyst had no effect on toluene and did not initiate side reactions. Furthermore, in systems containing toluene and other impurities in the pyrolysis oil, the catalyst still achieved efficient styrene conversion (disappearance of the styrene peak) and highly selective ethylbenzene production, while suppressing polymerization side reactions. This demonstrates that the catalyst of this application maintains good activity and selectivity in systems where toluene is present.

[0065] Example 3 Multiple constructions Ni 1.5 Al-LDO catalyst preparation and application (reaction conditions: 100ml reaction vessel, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0066] The Ni / Al molar ratio was changed as follows: 0.015 mol Ni(NO3)2·6H2O and 0.01 mol Al(NO3)3·9H2O were dissolved in 50 mL of deionized water and stirred for 1 h until completely dissolved to obtain a nitrate mixed solution; 0.015 mol sodium carbonate was dissolved in 100 mL of deionized water and stirred for 1 h until completely dissolved to obtain a sodium carbonate aqueous solution.

[0067] The other operating procedures are the same as in Example 2.

[0068] The results are as follows Figure 1 As shown, the test results indicate that the styrene concentration in the system is close to 0, the ethylbenzene concentration is approximately 41.85 μg / mL, and the toluene content remains essentially unchanged. Figure 1(a)); styrene conversion rate 100% ( Figure 1 (c) ), ethylbenzene selectivity 86% ( Figure 1 (d), the H2 pressure drop is approximately 2.7 MPa ( Figure 1 (b)

[0069] Example 4 Preparation and application of multiple Ni1Al-LDO catalysts (reaction conditions: 100ml reactor, 20g pyrolysis oil (45% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0070] The Ni / Al molar ratio was changed as follows: 0.01 mol Ni(NO3)2·6H2O and 0.01 mol Al(NO3)3·9H2O were dissolved in 50 mL of deionized water and stirred for 1 h until completely dissolved to obtain a nitrate mixed solution; 0.01 mol sodium carbonate was dissolved in 100 mL of deionized water and stirred for 1 h until completely dissolved to obtain a sodium carbonate aqueous solution.

[0071] The other operating procedures are the same as in Example 2.

[0072] The results are as follows Figure 1 As shown, the test results indicate that the styrene concentration in the system was 3.2 μg / mL, the ethylbenzene concentration was approximately 41.8 μg / mL, and the toluene content remained essentially unchanged. Figure 1 (a)); styrene conversion rate 93% ( Figure 1 (c) ), ethylbenzene selectivity 100% ( Figure 1 In the middle (d), the H2 pressure drop was approximately 2.3 MPa. Figure 1 (b)

[0073] Example 5 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 100ml reactor, 20g pyrolysis oil (45.8% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.05g).

[0074] The catalyst was prepared in the same manner as in Example 2.

[0075] During the catalyst performance evaluation process, the catalyst dosage was changed to 0.05g, and other operations were the same as in Example 2.

[0076] The results are as follows Figure 2 As shown, the test results indicate that the concentration of styrene in the system is approximately 0 μg / mL, the concentration of toluene is approximately 2 μg / mL, and the concentration of ethylbenzene is approximately 45.5 μg / mL. Figure 2(a)); styrene conversion rate 100% ( Figure 2 (c) ), ethylbenzene selectivity 100% ( Figure 2 In the middle (d), the H2 pressure drop is approximately 2.5 MPa. Figure 2 (b)

[0077] Example 6 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 100ml reactor, 20g pyrolysis oil (45% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0078] The preparation and performance evaluation of the catalyst are the same as in Example 2.

[0079] The results are as follows Figure 2 As shown, the test results indicate that the concentration of styrene in the system is approximately 0 μg / mL, the concentration of toluene is approximately 3 μg / mL, and the concentration of ethylbenzene is approximately 42 μg / mL. Figure 2 (a)); styrene conversion rate 100% ( Figure 2 (c) ), ethylbenzene selectivity 87.5% ( Figure 2 In the middle (d), the H2 pressure drop was approximately 2.3 MPa. Figure 2 (b)

[0080] Example 7 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 100ml reactor, 20g pyrolysis oil (45% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.2g).

[0081] The catalyst was prepared in the same manner as in Example 2.

[0082] During the catalyst performance evaluation process, the catalyst dosage was changed to 0.2g, and other operations were the same as in Example 2.

[0083] The results are as follows Figure 2 As shown, the detection results indicate that the concentrations of styrene, toluene, and ethylbenzene in the system are approximately 2 μg / mL, 2 μg / mL, and 41 μg / mL, respectively. Figure 2 (a)); styrene conversion rate 95.6% ( Figure 2 (c) ), ethylbenzene selectivity 100% ( Figure 2 In the middle (d), the H2 pressure drop is approximately 2.5 MPa. Figure 2 (b)

[0084] Example 8 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 500ml reactor, 100g pyrolysis oil (45% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.5g) The catalyst was prepared in the same manner as in Example 2.

[0085] During the catalyst performance evaluation process, compared with Example 6, the pyrolysis oil and catalyst were scaled up proportionally, with 100g of pyrolysis oil and 0.5g of catalyst added, and other operations were the same as in Example 6.

[0086] The results are as follows Figure 2 As shown, the test results indicate that the styrene concentration in the system is close to 0, and the ethylbenzene concentration is approximately 40.95 μg / mL. Figure 2 (a)); styrene conversion rate 100% ( Figure 4 (c) ), ethylbenzene selectivity 91% ( Figure 4 In the middle (d), the H2 pressure drop was approximately 2.4 MPa. Figure 4 (b)

[0087] Example 9 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 500ml reactor, 100g pyrolysis oil, 100℃, 4MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.5g).

[0088] The catalyst was prepared in the same manner as in Example 2.

[0089] During the catalyst performance evaluation process, the H2 pressure was changed by 4 MPa, and other operations were the same as in Example 8.

[0090] The test results showed that the styrene concentration in the system was approximately 2.25 μg / mL, and the ethylbenzene concentration was approximately 40.05 μg / mL; the styrene conversion rate was 95%, the ethylbenzene selectivity was 93.7%, and the H2 pressure drop was approximately 1.9 MPa.

[0091] Example 10 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 500ml reactor, 100g pyrolysis oil, 100℃, 3MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.5g).

[0092] The catalyst was prepared in the same manner as in Example 2.

[0093] During the catalyst performance evaluation process, the H2 pressure was changed by 3 MPa, and other operations were the same as in Example 8.

[0094] The test results showed that the styrene concentration in the system was approximately 6.75 μg / mL, and the ethylbenzene concentration was approximately 35.05 μg / mL; the styrene conversion rate was 85%, the ethylbenzene selectivity was 91.6%, and the H2 pressure drop was approximately 1.5 MPa.

[0095] Example 11 Preparation and application of multiple Ni2Al-LDO catalysts (reaction conditions: 1000ml reactor, 200g pyrolysis oil, 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 1g).

[0096] The catalyst was prepared in the same manner as in Example 2.

[0097] During the catalyst performance evaluation process, the amount of pyrolysis oil and catalyst was scaled up proportionally based on Example 8 (200g pyrolysis oil, 1g catalyst), and other operations were the same as in Example 8.

[0098] The test results showed that the concentration of styrene in the system was about 3 μg / mL, the concentration of toluene was about 1.5 μg / mL, and the concentration of ethylbenzene was about 40.5 μg / mL; the styrene conversion rate was 93.4%, the ethylbenzene selectivity was 96.9%, and the H2 pressure drop was about 4.8 MPa.

[0099] The specific surface area, pore volume, and pore size of the catalyst samples were determined using a physical adsorption analyzer (Micromeritics ASAP2020PLUS1D88). Specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method, while pore size and pore volume were determined using the Barrett-Joyner-Halenda (BJH) and Hovath-Kawazoe (H–K) methods. The results are shown in Table 1.

[0100] Table 1 shows the Ni configurations with multiple structures. x Specific surface area (BET), pore size and pore volume of Al-LDO

[0101] Comparative Example 1 Preparation and application of Ni / Al2O3 (1:1) catalyst (reaction conditions: 100ml reaction vessel, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0102] Preparation method: Weigh 0.01 mol of nickel nitrate and 0.01 mol of alkaline γ-Al2O3, dissolve the nickel nitrate and γ-Al2O3 powders in 50 mL of deionized water, place the mixture in a 60℃ constant temperature water bath, and impregnate for 5 h with magnetic stirring at 650 r / min. Transfer the impregnation solution to an 80℃ oven and dry for 12 h until completely dry to obtain catalyst Ni / Al2O3 1:1.

[0103] Application of catalytic pyrolysis oil: Reaction conditions: 100ml reaction vessel, 20g pyrolysis oil, 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g.

[0104] The evaluation method is the same as in Example 1, and the results are as follows: Figure 4 As shown, the detection results indicate that the concentration of styrene in the system is approximately 1.8 μg / mL, the concentration of toluene is approximately 1.47 μg / mL, and the concentration of ethylbenzene is approximately 24.12 μg / mL. Figure 4 (a)); styrene conversion rate 95.59% ( Figure 4 (c) ), ethylbenzene selectivity 45.78% ( Figure 4 In the middle (d), the H2 pressure drop is approximately 2 MPa. Figure 4 (b)

[0105] Comparative Example 2 Preparation and application of Ni / Al2O3 (1.5:1) catalyst (reaction conditions: 100ml reaction vessel, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0106] Preparation method: Weigh 0.015 mol of nickel nitrate and 0.01 mol of alkaline γ-Al2O3, dissolve the nickel nitrate and γ-Al2O3 powders in 50 mL of deionized water, place the mixture in a 60℃ constant temperature water bath, and impregnate for 5 h with magnetic stirring at 650 r / min. Transfer the impregnation solution to an 80℃ oven and dry for 12 h until completely dry to obtain catalyst Ni / Al2O3 1.5:1.

[0107] Application of catalytic pyrolysis oil: Reaction conditions: 100ml reaction vessel, 20g pyrolysis oil, 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g.

[0108] The evaluation method is the same as in Example 1, and the results are as follows: Figure 4As shown, the detection results indicate that the concentration of styrene in the system is approximately 0 μg / mL, the concentration of toluene is approximately 1.36 μg / mL, and the concentration of ethylbenzene is approximately 26.12 μg / mL. Figure 4 (a)); styrene conversion rate 100% ( Figure 4 (c) ), ethylbenzene selectivity 48.58% ( Figure 4 In the middle (d), the H2 pressure drop was approximately 2.1 MPa. Figure 4 (b)

[0109] Comparative Example 3 Preparation and application of Ni / Al2O3 (2:1) catalyst (reaction conditions: 100ml reaction vessel, 20g pyrolysis oil (48.6% styrene), 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g).

[0110] Preparation method: Weigh 0.02 mol of nickel nitrate and 0.01 mol of alkaline γ-Al2O3, dissolve the nickel nitrate and γ-Al2O3 powders in 50 mL of deionized water, place the mixture in a 60℃ constant temperature water bath, and impregnate for 5 h with magnetic stirring at 650 r / min. Transfer the impregnation solution to an 80℃ oven and dry for 12 h until completely dry to obtain the catalyst Ni / Al2O3 2:1.

[0111] Application of catalytic pyrolysis oil: Reaction conditions: 100ml reaction vessel, 20g pyrolysis oil, 100℃, 5MPa H2, 600rpm, reaction time 12h, catalyst dosage 0.1g.

[0112] The evaluation method is the same as in Example 1, and the results are as follows: Figure 4 As shown, the detection results indicate that the concentration of styrene in the system is approximately 1.9 μg / mL, the concentration of toluene is approximately 2.67 μg / mL, and the concentration of ethylbenzene is approximately 39.93 μg / mL. ​ (a)); styrene conversion rate 95.42% ( ​ (c) ), ethylbenzene selectivity 85.80% ( ​ In the middle (d), the H2 pressure drop is approximately 2.5 MPa. ​ (b)

[0113] Results analysis: Performance differences between single-layer and multi-layer build-up processes: The results of Examples 1 and 2 show that the BET of monolayer Ni2Al-LDO is only 183 m² / g, with a styrene conversion rate of 65% and a selectivity of 72%. However, the dual-construction process increases the BET of Ni2Al-LDO to 217 m² / g (an increase of 18.6%), raises the conversion rate to 100%, and improves the selectivity to 87%, proving that the ordered stacked structure of multiple constructions is the core factor for achieving high conversion and high selectivity.

[0114] Ni / Al molar ratio alignment for multiple Ni constructions x Regulation of Al-LDO: Examples 2-4 (100ml reactor) show that when Ni / Al=2, the optimal balance between conversion (100%) and selectivity (87%) is achieved, and the H2 utilization efficiency is the highest (pressure drop 2.3MPa). When Ni / Al=1.5, although the conversion reaches 100%, the selectivity decreases slightly (86%) and H2 consumption increases (pressure drop 2.7MPa). When Ni / Al=1, the conversion drops to 92%, and although the selectivity increases to 93%, the overall efficiency decreases. Therefore, Ni / Al=2 is the optimal composition.

[0115] Catalyst dosage suitability: Examples 5-7 (100ml reactor) verified that when the pyrolysis oil was 20g, the Ni / Al=2 multi-component catalyst maintained high efficiency in the dosage range of 0.05-0.2g: 100% conversion and 100% selectivity were achieved at 0.05g, and the conversion rate was still 95.6% and the selectivity was 95.3% at 0.2g, which is suitable for the dosage requirements of different processing scales.

[0116] Large-scale adaptation of reaction conditions: Examples 8-11 show that the catalyst is stable and efficient in 100-1000ml reactors and 3-5MPa H2 range: 0.5g of catalyst in a 500ml reactor treats 100g of pyrolysis oil with a conversion rate of 85%-100%; 1g of catalyst in a 1000ml reactor treats 200g of pyrolysis oil with a conversion rate of over 93%, demonstrating potential suitability for industrial scale-up.

[0117] By comparison, it can be seen that the Ni prepared by the method of this application... xComparative experiments between Al-LDO catalysts and mature Ni / Al2O3 catalysts based on commercial Al2O3 supports show that the former exhibits superior overall performance: the former can directionally convert ethylbenzene, while in the latter Ni / Al2O3 catalyst, part of the styrene is converted to ethylbenzene, and the other part undergoes self-polymerization to form a high molecular weight polymer; the former maintains a stable ethylbenzene selectivity of over 85%, with performance fluctuations far less than the latter (selectivity is only around 45% when Ni / Al ratio is low); at the same time, the former has a more stable hydrogen pressure drop, better side reaction suppression effect, and can still maintain efficient and stable conversion and selectivity in systems containing impurities in pyrolysis oil, demonstrating outstanding comprehensive advantages.

[0118] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. Application of multi-constructed layered metal oxide in polystyrene waste plastic pyrolysis oil in the hydrogenation conversion of styrene to ethylbenzene, characterized in that, The preparation of the multi-constructed layered metal oxide comprises: (1) Under constant temperature conditions of 30-40°C, a mixed aqueous solution containing nitrate salts of Ni 2+ and Al 3+ is added dropwise to an aqueous solution of sodium carbonate, stirring is continuously maintained and the pH value of the reaction system is maintained at 10.0±0.3 during the dropwise addition; after the dropwise addition is completed, the reaction is continuously stirred for 6-12 hours to obtain a mixed solution; the obtained mixed solution is left to stand at room temperature for aging for 10-12 hours, then washed to neutral, dried, and ground to obtain a single-layer Ni x Al LDH intermediate product; (2) The obtained all single-layer Ni x The intermediate product of Al LDH is re-dispersed into the same sodium carbonate aqueous solution as in step (1); then the same nitrate mixed aqueous solution as in step (1) is added dropwise into the sodium carbonate aqueous solution; the operation in step (1) is synchronized during the dropwise addition process, and the obtained mixture is treated by the process in step (1) to obtain double-layer Ni x Al LDH intermediate product; (3) The obtained double-layer Ni x Al LDH intermediate product, repeat the operation of step (2) until n-layer Ni x Al LDH intermediate product; (4) the obtained n layers of Ni x The multiple-constructed layered metal oxide is obtained by calcining and activating the intermediate product of Al LDH. The application comprises: After the multi-constructed layered metal oxide is used as a catalyst and is pretreated, it is fully mixed with polystyrene waste plastic pyrolysis oil, then is transferred to a reaction kettle, hydrogen is filled into the reaction kettle after being sealed, the reaction temperature is controlled to be 90-100℃, and stirring reaction is carried out for 6-12h.

2. Use according to claim 1, characterized in that, The molar ratio of Ni 2+ and Al 3+ in the nitrate mixed aqueous solution is 1-2:1; the mixing ratio of the sodium carbonate aqueous solution and the nitrate mixed aqueous solution is calculated based on the molar ratio of sodium carbonate and Ni 2+ of 1:

1.

3. Use according to claim 1, characterized in that, Ni in nitrate mixed aqueous solution 2+ The concentration is 0.2~0.4 M, Al 3+ The concentration of the sodium carbonate solution is 0.1~0.2 M; the concentration of the sodium carbonate aqueous solution is 0.1~0.2 M; the volume ratio of the nitrate mixed aqueous solution to the sodium carbonate aqueous solution is based on the ratio of sodium carbonate to Ni 2+ The molar ratio is 1:

1.

4. Use according to claim 1, characterized in that, The temperature of the calcination activation is 400-500℃, and the time is 4-6h.

5. The use according to claim 1, characterized in that, The mass percentage content of styrene in the polystyrene waste plastic pyrolysis oil is 40-50%, and the amount of the catalyst is 0.25-1% of the mass of the polystyrene waste plastic pyrolysis oil.

6. Use according to claim 1, characterized in that, The filling amount of hydrogen is 3-5MPa of hydrogen pressure in the reaction kettle, and the reaction temperature is 100℃.

7. A method for the preparation of a multi-layered metal oxide build-up, characterized in that comprises: (1) Under constant temperature conditions of 30-40°C, a mixed aqueous solution containing nitrate salts of Ni 2+ and Al 3+ is added dropwise to an aqueous solution of sodium carbonate, stirring is continuously maintained and the pH value of the reaction system is maintained at 10.0±0.3 during the dropwise addition; after the dropwise addition is completed, the reaction is continuously stirred for 6-12 hours to obtain a mixed solution; the obtained mixed solution is left to stand at room temperature for aging for 10-12 hours, then washed to neutral, dried, and ground to obtain a single-layer Ni x Al LDH intermediate product; (2) The obtained all single-layer Ni x The intermediate product of Al LDH is re-dispersed into the same sodium carbonate aqueous solution as in step (1); then the same nitrate mixed aqueous solution as in step (1) is added dropwise into the sodium carbonate aqueous solution; the operation in step (1) is synchronized during the dropwise addition process, and the obtained mixture is treated by the process in step (1) to obtain double-layer Ni x Al LDH intermediate product; (3) The obtained double-layer Ni x Al LDH intermediate product, repeat the operation of step (2) until n-layer Ni x Al LDH intermediate product; (4) the obtained n layers of Ni x The multiple-constructed layered metal oxide is obtained by calcining and activating the intermediate product of Al LDH.

8. The preparation method according to claim 7, characterized in that, The molar ratio of Ni 2+ and Al 3+ in the nitrate mixed aqueous solution is 1-2:1; the mixing ratio of the sodium carbonate aqueous solution and the nitrate mixed aqueous solution is calculated based on the molar ratio of sodium carbonate and Ni 2+ of 1:

1.

9. The preparation method according to claim 7, characterized in that, Ni in nitrate mixed aqueous solution 2+ The concentration is 0.2~0.4 M, Al 3+ The concentration of the sodium carbonate solution is 0.1~0.2 M; the concentration of the sodium carbonate aqueous solution is 0.1~0.2 M; the volume ratio of the nitrate mixed aqueous solution to the sodium carbonate aqueous solution is based on the ratio of sodium carbonate to Ni 2+ The molar ratio is 1:

1.

10. The multi-constructed layered metal oxide prepared by the preparation method in any one of claims 7-9.

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