Method for preparing alpha-terpinyl methyl ether from waste tire pyrolytic oil

Abstract

The invention provides a method for preparing alpha-terpinyl methyl ether from waste tire pyrolytic oil. The method comprises the following steps: firstly, fractionating the waste tire pyrolytic oil to obtain a limonene-enriched fraction, and carrying out catalytic alkoxylation on limonene in the fraction by using a heteropolyacid-loaded molecular sieve catalyst to obtain alpha-terpinyl methyl ether. According to different boiling points of alpha-terpinyl methyl ether and p-cymene and other aromatic hydrocarbon substances, separation and recovery of alpha-terpinyl methyl ether and other aromatic hydrocarbons can be realized through reduced pressure distillation. The method is characterized in that the alpha-terpinyl methyl ether is prepared from the waste tire pyrolytic oil, and the problem that limonene and p-cymene are difficult to separate and utilize due to similar physicochemical properties is solved. The prepared alpha-terpinyl methyl ether has wide application in industry, the value of the alpha-terpinyl methyl ether is equal to or higher than that of limonene, the alkoxylation reaction condition is mild, the subsequent separation process is simple and controllable, and a new thought can be provided for resource utilization of waste tire pyrolytic oil.

Description

Technical Field

[0001] The invention belongs to the field of high-value utilization and resource recovery of waste tires, and more specifically, relates to a method for preparing alpha-pinene methyl ether by using waste tire pyrolysis oil as a raw material. Background Art

[0002] With the development of science and technology and the improvement of living standards, the number of cars has increased year by year, and the "black pollution" problem caused by waste tires has become increasingly serious. Pyrolysis is an effective way to realize the resource utilization and harmlessness of waste tires. It is one of the main products of waste tire pyrolysis and can be used as a fuel substitute. Pyrolysis oil is rich in high-value compounds such as limonene and para-cymene. If it is directly burned, it will inevitably cause a lot of resource waste. Therefore, it needs to be separated before it can be used. However, the physical and chemical properties of limonene and para-cymene are very similar (boiling points are around 176°C). It is impossible to obtain high-purity limonene simply through distillation, resulting in the inability to further utilize limonene.

[0003] Terpenes can react with fatty alcohols to form terpene ethers under acid catalysis. Terpene ethers are generally colorless or light yellow liquids, insoluble in water, and soluble in most organic solvents. Terpene ethers have a unique and long-lasting aroma, so they are often used in the daily chemical industry, such as the manufacture of perfumes, cosmetics, and air fresheners. Some terpene ethers also have antibacterial, anti-inflammatory, or antioxidant properties, and can be used to treat various infections, skin diseases, respiratory diseases, etc. Limonene can react with methanol to form α-pinene methyl ether through alkoxylation. The boiling point of α-pinene methyl ether (about 200°C) is quite different from that of para-cymene, and can be separated by distillation. The preparation of α-pinene methyl ether from waste tire pyrolysis oil can not only realize the recycling of limonene, but also help improve the economy and resource utilization of waste tire pyrolysis oil. Summary of the invention

[0004] Aiming at the problem that limonene and p-cymene are difficult to separate in waste tire pyrolysis oil, the present invention proposes a method for preparing α-pinene methyl ether by using waste tire pyrolysis oil, which converts limonene in tire pyrolysis oil into high-value α-pinene methyl ether, improves the economy and resource utilization of tire pyrolysis oil, and α-pinene methyl ether has a large difference in boiling point from other interfering components such as p-cymene, and can be directly separated from the raw material by distillation. In addition, the aromatic hydrocarbon components in the pyrolysis oil do not participate in the alkoxylation reaction process, and a fraction rich in aromatic hydrocarbons can be obtained after the reaction, which can be further utilized.

[0005] The technical scheme adopted by the present invention is as follows: first, the tire pyrolysis oil is fractionated to collect the fraction with a boiling point between 160-180°C, which contains more limonene and p-cymene. The fraction rich in limonene and p-cymene is pretreated to remove some heteroatom compounds and water, the pretreated oil sample is mixed with methanol, a molecular sieve catalyst loaded with heteropolyacid is added, and the mixture is placed in a water bath and heated to 40-70°C and stirred, and the alkoxylation reaction time is 1-5h. After the reaction is completed, the catalyst is centrifuged and the oil sample is rotary evaporated at 75°C to remove excess methanol. The reacted oil sample is subjected to reduced pressure distillation, with a cutting temperature of 70-80°C, and the obtained distillate is a fraction rich in aromatic hydrocarbons, and the bottoms are a fraction rich in α-pine oil methyl ether.

[0006] Furthermore, the pretreatment of the fraction rich in limonene and p-cymene according to the present invention specifically comprises the following steps: the fraction rich in limonene and p-cymene is mixed with an equal mass of polyethylene glycol and extracted 2-4 times, each time for 8-12 minutes, after extraction, the upper layer liquid is poured out, excess anhydrous Na2SO4 is added and the mouth is sealed to remove water. Preferably, the extraction times are 3 times, each time for 10 minutes.

[0007] Furthermore, the amount of methanol added in the present invention is based on the content of limonene in the sample, and the mass ratio of limonene to methanol is 1:1-1:4. Preferably, the mass ratio of limonene to methanol is 1:3, that is, if the sample contains 1g of limonene, the amount of methanol added is 3g.

[0008] Further, the molecular sieve catalyst loaded with heteropoly acid of the present invention is specifically prepared as follows: the molecular sieve is calcined in a muffle furnace at 550° C. for 4 hours to remove the template before use. 0.5-2.5 g of heteropoly acid is dissolved in 100 mL of deionized water. 5 g of molecular sieve is added and stirred at 30° C. for 8 hours to impregnate it, and then the water is evaporated at 90° C., dried in an oven at 105° C. overnight, and finally calcined at 300° C. for 4 hours in a muffle furnace to obtain a molecular sieve catalyst with a heteropoly acid loading of 10-50 wt.%. Preferably, Hβ molecular sieve (Si / Al=25) is used as a catalyst carrier, and the heteropoly acid is phosphotungstic acid (HPW) with a loading of 40 wt.%.

[0009] Furthermore, the amount of catalyst added to the Hβ molecular sieve loaded with heteropolyacid of the present invention is based on the content of limonene in the sample, and the amount of catalyst added is 10-50% of the mass of limonene in the sample. Preferably, the amount of catalyst added is 30% of the mass of limonene in the sample, that is, if the sample contains 1g of limonene, the amount of catalyst added is 0.3g.

[0010] Furthermore, the water bath heating temperature of the present invention is 60°C.

[0011] Furthermore, the cutting temperature is preferably 75°C.

[0012] Compared with the prior art, the beneficial effects of the solution of the present invention are as follows:

[0013] (1) The physical and chemical properties of limonene and p-cymene in waste tire pyrolysis oil are very similar, making it difficult to effectively separate them by traditional separation methods, thus limiting their further utilization in various fields. However, after in-depth research, it was found that if the limonene in the pyrolysis oil is converted into α-pinene methyl ether, the boiling point of this conversion product will be significantly different from that of p-cymene. Based on this discovery, we proposed an innovative separation strategy: using vacuum distillation technology, α-pinene methyl ether and p-cymene can be efficiently separated. This method not only solves the technical bottleneck of the difficulty in separating and utilizing limonene and p-cymene in waste tire pyrolysis oil, but also opens up a new way for the high-value utilization of waste tire resources, which is of great significance for promoting circular economy and sustainable development.

[0014] (2) The alkoxylation reaction conditions provided by the present invention are specially designed to be carried out under normal pressure and 60°C. Compared with the traditional high temperature and high pressure reaction environment, this condition is particularly mild, greatly reducing the requirements for production equipment, thereby helping to reduce energy consumption and costs in the production process. More importantly, the present invention uses a Hβ molecular sieve loaded with heteropolyacid as a catalyst, which exhibits high selectivity in the synthesis reaction of α-pinene methyl ether, ensuring the efficient generation of the target product. In addition, the catalyst also has good recyclability, which is convenient for recycling in the production process and reduces the consumption of the catalyst. Compared with traditional liquid acid catalysts, the catalyst has significant environmental friendliness and will not cause pollution to the environment. More importantly, after regeneration treatment, the catalytic performance of the catalyst is still stable, and it can continue to maintain efficient catalytic activity, which fully meets the development requirements of green chemistry and provides strong technical support for promoting the green development of the chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The GC-MS spectra of the oil samples before and after the alkoxylation reaction are shown in Figure 2. 160-180℃ For oil samples enriched with limonene, E-TPO 160-180℃ For pre-treated oil samples, RE-TPO 160-180℃ This is the oil sample after alkoxylation reaction. DETAILED DESCRIPTION

[0016] The present method is further described below by specific examples and comparative examples, but the present invention is not limited thereby. The following non-limiting examples can enable ordinary technicians in the field to understand the present invention more comprehensively, but do not limit the present invention in any way.

[0017] The test methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0018] Hβ molecular sieve (Si / Al=25) was used as the catalyst carrier, and was calcined in a muffle furnace at 550°C for 4h to remove the template before use. 2.0g of phosphotungstic acid (HPW) was dissolved in 100mL of deionized water, 5g of Hβ molecular sieve was added and stirred at 30°C for 8h to impregnate, and then the water was evaporated at 90°C and dried in an oven at 105°C overnight, and finally calcined at 300°C in a muffle furnace for 4h to obtain Hβ molecular sieve (40HPW / Hβ) with a phosphotungstic acid loading of 40wt.%.

[0019] Example 1

[0020] The method for preparing α-pinene methyl ether from waste tire pyrolysis oil provided in this example comprises the following steps:

[0021] (1) The waste tire pyrolysis oil is fractionated to obtain a fraction with a boiling point between 160 and 180° C., which is a limonene and p-cymene-enriched fraction.

[0022] (2) Add a certain amount of limonene and p-cymene enriched fractions to a beaker, and then add an equal volume of polyethylene glycol (PEG-600) for extraction. Repeat the extraction three times, each time for 10 minutes, pour out the upper liquid and add excess Na2SO4 to remove water, and filter to obtain the pretreated oil sample after dehydration. In this embodiment, the contents of limonene and aromatic hydrocarbons in the pretreated oil sample are 14.54% and 48.02%, respectively.

[0023] (3) Considering that other olefins in the oil sample may also undergo alkoxylation, the amount of methanol and catalyst added was appropriately increased. 8g of pretreated oil sample (containing about 1.10g of limonene), 4g of methanol and 0.4g of catalyst 40HPW / Hβ were added to the reactor in sequence, and the reaction was stirred at 60°C for 5h. After the reaction was completed, the catalyst was separated by centrifugation, and the oil sample was evaporated at 75°C to remove excess methanol. The conversion rate of limonene in the oil sample was 83.01% by gas chromatography, and the yield of the main product α-pinene methyl ether was 65.31%.

[0024] (4) The oil sample after the reaction in step (3) is subjected to reduced pressure distillation with a cutting temperature of 75° C. The distillate is a fraction enriched in aromatic hydrocarbons, wherein the content of aromatic hydrocarbons is 74.06%, and the bottom residue is a fraction enriched in terpene ethers, wherein the content of α-pinene methyl ether is 56.04%.

[0025] Comparative Example 1

[0026] 2g of tire pyrolysis oil model compound (containing 1g of limonene and 1g of para-cymene), 3g of methanol and 0.3g of unloaded Hβ molecular sieve catalyst were added to the reactor in sequence. The reaction was stirred at 60°C for 5h, and the catalyst was removed by centrifugation after the reaction. According to gas chromatography, the conversion rate of limonene was 50.30%, and the yield of the main product α-pinene methyl ether was 36.29%.

[0027] Comparative Example 2

[0028] 2g of tire pyrolysis oil model compound (containing 1g of limonene and 1g of para-cymene), 3g of methanol and 0.3g of Hβ molecular sieve catalyst 20HPW / Hβ with a phosphotungstic acid loading of 20wt.% were added to the reactor in sequence. The reaction was stirred at 60°C for 5h, and the catalyst was removed by centrifugation after the reaction. According to gas chromatography, the conversion rate of limonene was 82.55%, and the yield of the main product α-pinene methyl ether was 60.92%.

[0029] Comparative Example 3

[0030] 2g of tire pyrolysis oil model compound (containing 1g of limonene and 1g of para-cymene), 3g of methanol and 0.3g of catalyst 40HPW / Hβ were added to the reactor in sequence. The reaction was stirred at 70°C for 5h, and the catalyst was removed by centrifugation after the reaction. According to gas chromatography, the conversion rate of limonene was 82.25%, and the yield of the main product α-pinene methyl ether was 58.11%.

[0031] Comparative Example 4

[0032] 2g of tire pyrolysis oil model compound (containing 1g of limonene and 1g of para-cymene), 1g of methanol and 0.3g of catalyst 40HPW / Hβ were added to the reactor in sequence. The reaction was stirred at 60°C for 5h, and the catalyst was removed by centrifugation after the reaction. According to gas chromatography, the conversion rate of limonene was 75.82%, and the yield of the main product α-pinene methyl ether was 53.90%.

[0033] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing α-pinene methyl ether from waste tire pyrolysis oil, characterized in that: The preparation steps are as follows: first, waste tire pyrolysis oil is fractionated to obtain a fraction with a boiling point between 160 and 180°C, the fraction is pretreated to remove some impurities and water, a certain amount of methanol and a molecular sieve catalyst loaded with heteropoly acid are added, the fraction is placed in a water bath and heated to 40-70°C and stirred, and the reaction time is 1-5 hours; after the reaction is completed, the catalyst is separated by centrifugation; the oil sample after the reaction is subjected to reduced pressure distillation with a cutting temperature of 70-80°C, the distillate obtained is a fraction rich in aromatic hydrocarbons, and the bottoms are a fraction rich in α-pine oil methyl ether.

2. The method according to claim 1, characterized in that The specific steps of pretreatment of the fraction rich in limonene and p-cymene are: mixing the fraction rich in limonene and p-cymene with an equal volume of polyethylene glycol and extracting it 2-4 times, each time for 8-12 minutes, pouring out the upper liquid after extraction, adding excessive anhydrous Na2SO4 and sealing it to remove water, and obtaining the pretreated oil sample after filtering.

3. The method according to claim 1, characterized in that The amount of methanol added is based on the mass of limonene in the sample, and the mass ratio of limonene to methanol is 1:1-1:

4.

4. The method according to claim 3, characterized in that The mass ratio of limonene to methanol is 1:

3.

5. The method according to claim 1, characterized in that The specific preparation steps of the molecular sieve catalyst loaded with heteropoly acid are as follows: before use, the molecular sieve is calcined at 550° C. for 4 hours in a muffle furnace to remove the template; 0.5-2.5 g of heteropoly acid is dissolved in 100 mL of deionized water, 5 g of molecular sieve is added and stirred at 30° C. for 8 hours to impregnate it, then the water is evaporated at 90° C. and dried at 105° C. overnight, and finally calcined at 300° C. for 4 hours in a muffle furnace to obtain a molecular sieve catalyst with a heteropoly acid loading of 10-50 wt.%.

6. The method according to claim 5, characterized in that The molecular sieve is Hβ molecular sieve (Si / Al=25), the heteropoly acid is phosphotungstic acid, and the loading amount is 40wt.%.

7. The method according to claim 1, characterized in that The amount of the catalyst added is 10-50% of the mass of the limonene in the sample.

8. The method according to claim 7, characterized in that The amount of catalyst added is 30% of the mass of limonene in the sample.

9. The method according to claim 1, characterized in that: The water bath heating temperature is 60°C.

10. The method according to claim 1, characterized in that The cutting temperature is 75°C.

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