CN107008499B - Combined catalyst and method for converting terpenoids to aromatic hydrocarbons - Google Patents

Abstract

The invention provides a combined catalyst and method capable of converting terpenoids into aromatic hydrocarbons. The combined catalyst capable of converting terpenoids into aromatic hydrocarbons is characterized in that it contains at least one of superacids and polybasic heteropolyacids. The combined catalyst is easier to prepare and lower in cost. When using this catalyst, the reaction conditions are milder, and the conversion rate and selectivity are high, which can solve the problem of low reaction efficiency, expensive catalyst, and reaction problems in the existing conversion from terpenoids to aromatic hydrocarbons. Harsh conditions and other defects provide a green, cheap and efficient way for the conversion of terpenoids into aromatic hydrocarbons.

Description

Combined catalyst and method for converting terpenoids to aromatic hydrocarbons

technical field

The invention relates to a combined catalyst and method capable of converting terpenoids into aromatic hydrocarbons.

Background technique

Aromatic hydrocarbons are important raw materials of organic chemical industry, mainly derived from non-renewable resources such as coal, tar and petroleum. Seeking to produce aromatic hydrocarbons from renewable resources is very necessary for energy saving and emission reduction, as well as reducing the industry's dependence on petroleum resources. Terpenoids are important renewable biomass resources, widely distributed in nature, with diverse structures and abundant reserves. Converting renewable terpenoids into aromatic hydrocarbons through catalytic reforming and oxidation reactions is a new approach for biomass conversion.

As early as 1938, Palmer et al. used Cu-Ni alloy as a reforming catalyst to disproportionate monocyclic terpene at 170-190°C to obtain p-cymene and p-menthane, which can be separated by distillation ( US Patent 2211432). Since then, most of the related studies have used transitions or their compounds as catalysts, and the reaction conditions are mostly harsh. For example, in 2010, Leita et al. used a Pd catalyst supported on γ-Al ₂ O ₃ to convert eucalyptol into p-cymene under the conditions of O ₂ , Ar mixed gas, and 250-350°C (WO2011/006183 ), but the raw materials for preparing this catalyst are more expensive, and the catalytic reaction conditions are also harsher.

It can be seen that the existing methods for converting terpenoids into aromatic hydrocarbons are limited, the required catalysts are relatively expensive, and the reaction conditions are harsh, so there is much room for improvement.

Contents of the invention

The object of the present invention is to provide a catalyst capable of converting terpenoids into aromatic hydrocarbons under mild conditions and to provide a method for converting terpenoids into aromatic hydrocarbons using the catalyst.

In order to achieve the above object, the present invention provides a combined catalyst capable of converting terpenoids into aromatic hydrocarbons, which is characterized in that it contains at least one of superacids and polybasic heteropolyacids.

Preferably, the superacid is trifluoromethanesulfonic acid (CF ₃ SO ₃ H, or HOTf) or bistrifluoromethanesulfonimide [(CF ₃ SO ₂ ) ₂ NH, or Tf ₂ NH].

Preferably, the polybasic heteropolyacid contains at least two of phosphorus, vanadium, molybdenum and tungsten.

Preferably, the polybasic heteropolyacid is H ₄ [PMo ₁₁ VO ₄₀ ], H ₅ [PMo ₁₀ V ₂ O ₄₀ ] or H ₆ [PMo ₉ V ₃ O ₄₀ ].

More preferably, the polybasic heteropolyacid is H ₄ [PMo ₁₁ VO ₄₀ ].

Preferably, the molar ratio of the superacid to the polybasic heteropolyacid is 0-25:1.

The present invention also provides a method for converting terpenoids into aromatic hydrocarbons, which is characterized in that it comprises: adding the reaction substrate terpenoids, the above-mentioned catalyst and solvent into a reaction vessel, introducing oxygen as an oxidizing agent, and converting the terpenoids Compounds are converted to aromatic hydrocarbons at a temperature of 50-80°C.

Preferably, the molar ratio of the terpenoids to the super acid is 100:0-15.

Preferably, additives are also added into the reaction vessel.

Preferably, tetraethylene glycol dimethyl ether is added as an additive in the reaction vessel, and the molar ratio of terpenoids to tetraethylene glycol dimethyl ether is 100:0-15.

Preferably, the terpenoids are eucalyptol, 1,4-cineole, terpineol, terpene-4-ol, γ-terpinolene, terpinolene or limonene.

Preferably, the aromatic hydrocarbon is p-cymene.

Preferably, the solvent is 1,2-dichloroethane or diethyl carbonate.

Compared with prior art, the beneficial effect of the present invention is:

The combined catalyst is easier to prepare and lower in cost. When using this catalyst, the reaction conditions are milder, and the conversion rate and selectivity are high, which can solve the problem of low reaction efficiency, expensive catalyst, and reaction problems in the existing conversion from terpenoids to aromatic hydrocarbons. Harsh conditions and other defects provide a green, cheap and efficient way for the conversion of terpenoids into aromatic hydrocarbons.

Description of drawings

Fig. 1 is the NMR spectrum of the initial mixed liquid liquid of reaction in embodiment 1;

Fig. 2 is the nuclear magnetic spectrum of reaction mixture liquid when embodiment 1 reacts 6 hours;

Fig. 3 is a structure diagram of substrates in Examples 1-38.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also belong to the scope defined by the appended claims of the present application.

Examples 1-30 use eucalyptol as a substrate as a template reaction to screen out the best reaction conditions. Examples 31-37 performed substrate expansion. All reactions in embodiment 1-30 are all with oxygen balloon as oxygen source, and 1,1,2,2-tetrachloroethane is as the NMR productive rate that internal standard survey calculates, and reaction substrate consumption is 2.5mmol, and reaction time is average for 6 hours. The molar percentages of each embodiment are based on the reaction substrate.

Example 1-3

A kind of method that terpenoids are converted into aromatic hydrocarbons, concrete steps are: in flask, add the mixture of reaction substrate eucalyptol, superacid HOTf and the polybasic heteropolyacid shown in table 1 (as oxidative dehydrogenation reaction catalyst), additives and solvents, feed oxygen as an oxidizing agent, and the oxygen flow rate is 1.0mL/min, and the reaction substrate eucalyptol is converted into aromatic hydrocarbon p-cymene under the condition that the temperature is constant at 70°C. Wherein, the dosage of HOTf is 5mol%, the dosage of polybasic heteropolyacid is 1mol%, the additive is tetraethylene glycol dimethyl ether, the dosage is 3mol%, the solvent is 5mL 1,2-dichloroethane, and the reaction time is 6 hours.

The product was analyzed by 500MHz liquid NMR spectrometer.

NMR spectrum of raw material eucalyptol: ¹ H NMR (500MHz, CDCl ₃ ) δ2.06-1.98 (m, 2H), 1.69-1.63 (m, 2H), 1.54-1.45 (m, 4H), 1.41 ( d, J=1.1 Hz, 1H), 1.24(s, 6H), 1.05(s, 3H). The NMR spectrum of the product p-cymene: ¹ H NMR (500MHz, CDCl ₃ ) δ7.14-7.09(m, 4H), 2.87(dt, J=13.8, 6.9Hz, 1H), 2.32(s, 3H ), 1.23 (d, J=6.9Hz, 6H). NMR spectrum of internal standard 1,1,2,2-tetrachloroethane: ¹ H NMR (500 MHz, CDCl ₃ ) δ5.96 (s, 2H).

Table 1: Experimental parameters for variation of heteropolyacid composition

Example Heteropoly acid catalyst (1mol%) p-Cymene (%) 1 H₄[PMo₁₁VO₄₀] 79 2 H₅[PMo₁₀V₂O₄₀] 66 3 H₆[PMo₉V₃O₄₀] 59

For Examples 1-3, it can be concluded that the catalytic activity of the H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid catalyst is the best.

Example of the method for calculating the product p-cymene by liquid NMR:

Before the reaction starts to heat, the initial mixture of the reaction system is sampled for NMR measurement (NMR spectrum as shown in Figure 1). After reacting for 6 hours, the reaction mixture was taken again for NMR measurement (NMR spectrum is shown in Figure 2). Taking internal standard 1,1,2,2-tetrachloroethane as benchmark, the content of eucalyptol can be determined by the methyl signal on the eucalyptol by Fig. The methine hydrogen signal determines the exact amount of product. Can calculate thus when reacting 6 hours, the productive rate of p-cymene is:

0.96÷(3.64÷3)×100%=79%.

Example 4-12

Similar to Example 1, the difference is that the proportions of HOTf and H ₄ [PMo11VO40] heteropolyacid catalyst and tetraethylene glycol dimethyl ether are different, as shown in Table 2 for details. Under the condition of fixed temperature and solvent, the change of product yield caused by the change of ratio of HOTf and H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid catalyst was studied.

Table 2: Experimental parameters for the ratio change of the two catalysts

Examples 1-12 give the optimal catalyst H ₄ [PMo ₁₁ VO ₄₀ ] and the optimal ratio of the product to be obtained economically and efficiently under the co-catalysis of it and HOTf.

Examples 13-16

Similar to Example 1, the difference is that the reaction temperature is different, as shown in Table 3. Using temperature as a single factor variable, studies were carried out at a catalyst ratio of 5 mol% HOTf and 0.5 mol% H ₄ [PMo ₁₁ VO ₄₀ ].

Table 3: Experimental parameters for temperature variation

Example temperature(℃) p-Cymene (%) 13 50 3 14 60 44 15 70 78 16 80 50

Examples 17-30

Similar to Example 1, the difference is that the solvents are different, as shown in Table 4. Solvent type was used as a single variable to screen for suitable reaction solvents.

Table 4: Experimental parameters for varying solvent types

From the above-mentioned Examples 17-30, the screening of solvents can be concluded that 1,2-dichloroethane and diethyl carbonate can be used as solvents to obtain the best product yield. Wherein in Examples 27 and 28, no additive tetraethylene glycol dimethyl ether was added, and the yield was obviously better than that of adding additives. Comparing the two solvents, diethyl carbonate is weaker in toxicity and more friendly to the environment. It is considered as a green solvent and has good reactivity. Therefore, diethyl carbonate is used as a solvent for more study of terpenoids.

Example 31

Conversion of eucalyptol to p-cymene

22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mol), 3L diethyl carbonate, 11mL trifluoromethanesulfonic acid (0.125 mol), 418mL eucalyptol (2.5 mol) were successively added into a 10L flask , feed oxygen as an oxidant, the oxygen flow rate is (0.78L/min), stir at 70°C for 6 hours, convert eucalyptol into p-cymene, and separate the product by distillation under reduced pressure. The quality of the isolated product was 232.3 g, and the yield was 69%.

Example 32

1,4-Cineole is converted to p-cymene:

22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mol), 3L diethyl carbonate, 11mL trifluoromethanesulfonic acid (0.125 mol), 435mL 1,4-cineole (2.5 mol), feed oxygen as an oxidant, the oxygen flow rate is (0.78L/min), stir at 70°C for 6 hours, convert 1,4-cineole into p-cymene, and separate the product by distillation under reduced pressure. The quality of the isolated product was 279.5 g, and the yield was 83%.

Example 33

Conversion of terpineol to p-cymene:

22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mol), 3L diethyl carbonate, 11mL trifluoromethanesulfonic acid (0.125 mol), 412mL terpineol (2.5 mol), Oxygen was introduced as an oxidizing agent, the oxygen flow rate was (0.78 L/min), stirred at 70° C. for 6 hours, terpineol was converted into p-cymene, and the product was obtained by distillation under reduced pressure. The quality of the isolated product was 242.6 g, and the yield was 72%.

Example 34

Conversion of terpene-4-ol to p-cymene:

22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mol), 3L diethyl carbonate, 11mL trifluoromethanesulfonic acid (0.125 mol), 415mL terpene-4-ol (2.5 mol), feed oxygen as an oxidant, the oxygen flow rate is (0.78L/min), stir at 70°C for 6 hours, convert terpene-4-ol into p-cymene, and separate the product by distillation under reduced pressure. The mass of the isolated product was 241.9 g, and the yield was 72%.

Example 35

Conversion of γ-terpinene to p-cymene:

Add 22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mole) successively in 10L flask, 3L diethyl carbonate, 401mL gamma-terpinene (2.5 mole), feed oxygen as oxidant, oxygen flow rate is ( 0.78L/min), stirred at 70°C for 6 hours, converted γ-terpinene into p-cymene, and separated by distillation under reduced pressure to obtain the product. The quality of the isolated product was 292.4 g, and the yield was 87%.

Example 36

Conversion of terpinolene to p-cymene:

22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 moles), 3L diethyl carbonate, 396mL terpinolene (2.5 moles) were added successively in a 10L flask, and oxygen was fed as oxidant, and the oxygen flow rate was ( 0.78L/min), stirred at 70°C for 6 hours, converted terpinolene into p-cymene, and separated by distillation under reduced pressure to obtain the product. The quality of the isolated product was 238.2 g, and the yield was 71%.

Example 37

Conversion of limonene to p-cymene:

Add 22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mole) successively in 10L flask, 3L diethyl carbonate, 404mL limonene (2.5 mole), feed oxygen as oxygenant, oxygen flow rate is (0.78L/ min), stirred at 70°C for 6 hours, converted limonene into p-cymene, and separated by distillation under reduced pressure to obtain the product. The quality of the isolated product was 265.1 g, and the yield was 79%.

Example 38

Conversion of eucalyptol to p-cymene

Add 22.275g H ₄ [PMo ₁₁ VO ₄₀ ] heteropolyacid (0.0125 mol), 3L diethyl carbonate, 35.1g bistrifluoromethanesulfonimide (0.125 mol), 418mL eucalyptol in a 10L flask (2.5 moles), feed oxygen as oxidizing agent, oxygen flow rate is (0.78L/min), 70 ℃ of stirring 6 hours, eucalyptol alcohol is converted into p-cymene, and vacuum distillation separates and obtains product. The quality of the isolated product was 245.0 g, and the yield was 73%.

The substrates in Examples 1-38 are shown in Figure 3.

Claims (6)

1. a combination catalyst that can convert terpenoids into aromatic hydrocarbons, is characterized in that, comprises superacid and polybasic heteropolyacid, and described superacid is trifluoromethanesulfonic acid or two trifluoromethanesulfonimides , the polybasic heteropoly acid is H ₄ [PMo ₁₁ VO ₄₀ ], H ₅ [PMo ₁₀ V ₂ O ₄₀ ] or H ₆ [PMo ₉ V ₃ O ₄₀ ]. 2. The combined catalyst capable of converting terpenoids into aromatic hydrocarbons as claimed in claim 1, characterized in that, said polybasic heteropolyacid contains at least two of phosphorus, vanadium, molybdenum and tungsten. 3 . The combined catalyst capable of converting terpenoids into aromatic hydrocarbons as claimed in claim 1 , wherein the molar ratio of the superacid to the polybasic heteropolyacid is 0 to 25:1, excluding 0. 4 . 4. a method that terpenoids are converted into aromatic hydrocarbons, is characterized in that, comprises: in reaction vessel, add reaction substrate terpenoids, catalyst and solvent described in any one of claim 1-3, by Oxygen is introduced as an oxidant to convert terpenoids into aromatic hydrocarbons at a temperature of 50-80°C. 5 . The method for converting terpenoids into aromatic hydrocarbons as claimed in claim 4 , wherein the molar ratio of the terpenoids to the super acid is 100:0-15. 6. the method that terpenoids are converted into aromatic hydrocarbons as claimed in claim 4, is characterized in that, described terpenoids are eucalyptol, 1,4-cineole, terpineol, terpene- 4-ol, gamma-terpinolene, terpinolene or limonene.