Polycyclic high-energy fuel and preparation method thereof

Abstract

The invention relates to a polycyclic high-energy fuel and a preparation method thereof. The preparation method of the polycyclic high-energy fuel comprises the following steps: by taking water as a solvent, under the combined action of a metal catalyst and a solid acid catalyst, enabling a lignin-derived phenolic compound to react in a hydrogen atmosphere, so as to obtain the polycyclic high-energy fuel. According to the method disclosed by the invention, water is taken as a solvent, and metal and solid acid are taken as catalysts, so that the lignin-derived phenolic compound is efficiently converted into the polycyclic high-energy fuel, and the yield of the polycyclic high-energy fuel is relatively high. And water is used as a solvent, the method is green and environment-friendly, the polycyclic high-energy fuel and water are in a two-phase system, and separation and purification of the product polycyclic high-energy fuel are facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of chemical engineering, and in particular to a polycyclic high-energy fuel and a preparation method thereof. Background Art

[0002] The synthesis process of traditional high-energy fuels relies on fossil energy such as petroleum and coal, which aggravates environmental pollution and energy depletion. The main components of high-energy fuels are polycyclic alkanes, and their green direction is mainly to use biomass energy as reaction raw materials. Among biomass energy, only lignin has an aromatic ring as the skeleton, which is an ideal raw material for synthesizing polycyclic alkanes. Phenol, guaiacol and 2,6-dimethoxyphenol are all basic components of lignin pyrolysis products. Among them, phenol has the simplest structure and is a commonly used phenolic model compound. However, in real lignin pyrolysis oil, the content of phenol is relatively small, and more of it is guaiacol, 2,6-dimethoxyphenol and its derivatives with complex structures. However, the current synthesis of high-energy fuels using guaiacol and more complex phenolic compounds as raw materials has the problem of low yield. Summary of the invention

[0003] In view of this, an embodiment of the present application provides a method for preparing a polycyclic high-energy fuel, which solves the problem of low yield of bio-based high-energy fuel in the prior art.

[0004] The first aspect of the present invention provides a method for preparing a polycyclic high-energy fuel, the method comprising:

[0005] Using water as solvent, under the joint action of a metal catalyst and a solid acid catalyst, lignin-derived phenolic compounds are reacted in a hydrogen atmosphere to obtain the polycyclic high-energy fuel.

[0006] Further, the metal catalyst comprises a supported metal catalyst, the supported metal catalyst comprises a metal active site and a carrier, and the metal active site is supported on the carrier;

[0007] Preferably, the metal active site comprises at least one of Pd, Pt, Ru and Rh, and the support comprises a porous material;

[0008] Preferably, the carrier comprises at least one of activated carbon, carbon nanotubes and mesoporous silica.

[0009] Furthermore, based on the total mass of the supported metal catalyst, the content of the metal active sites is 0.1%-10%.

[0010] Further, the solid acid catalyst comprises a zeolite molecular sieve having at least one structure of BETA, FAU and MWW;

[0011] Preferably, the solid acid catalyst includes at least one of Hβ, HY, USY, HX, MCM-22 and SSZ-25.

[0012] Furthermore, the mass ratio of the lignin-derived phenolic compound, the mass of the metal catalyst, the mass of the solid acid catalyst and water is (2-50):(0.02-0.5):(1-15):(6-120).

[0013] Furthermore, the structural formula of the lignin-derived phenolic compound includes at least one of formula (1) to formula (3):

[0014]

[0015] Among them, R1 includes H, C n H 2n+1 , C n+1 H 2n+1 and (CH2) n-1 One of CHO, wherein n is an integer greater than or equal to 1 and not more than 3.

[0016] Further, the lignin-derived phenolic compound includes at least one of phenol, guaiacol, 2,6-dimethoxyphenol, vanillin, vanillone, gingerone, 4-ethylphenol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol, 4-acetoneguaiacol, 4-methyl-2,6-dimethoxyphenol, 2-methoxy-4-propylphenol, 4-hydroxy-3,5-dimethoxyacetophenone, syringaldehyde, eugenol, isoeugenol and 4-propylguaiacol.

[0017] Further, the reaction is carried out under stirring conditions, and the pressure of the reaction is 5-7MPa;

[0018] Preferably, water is used as solvent, and under the combined action of a metal catalyst and a solid acid catalyst, the lignin-derived phenolic compound is reacted at 110-240° C. in a hydrogen atmosphere for 2-48 hours, and then the temperature is raised to 240-300° C. for further reaction for 2-48 hours.

[0019] Furthermore, before the reaction, air in the solvent is replaced.

[0020] The second aspect of the present invention provides a polycyclic high-energy fuel prepared by the above-mentioned preparation method, wherein the structural formula of the polycyclic high-energy fuel includes at least one of formula (4) to formula (11):

[0021]

[0022] R2 includes H and / or C nH 2n+1 , n is an integer greater than or equal to 1 and not more than 3.

[0023] The present invention uses phenolic compounds as raw materials, which are selectively hydrogenated under the action of a metal catalyst to generate a cyclic alcohol intermediate, and the cyclic alcohol and phenols undergo an alkylation reaction under the action of the acidic site of a solid acid catalyst to obtain a polycyclic skeleton, and finally the metal catalyst and the acidic site in the solid acid catalyst synergistically catalyze a hydrogenation deoxygenation reaction to generate saturated polycyclic alkanes. Therefore, the metal catalyst and the solid acid catalyst are used as catalysts to achieve efficient conversion of lignin-derived phenolic compounds into polycyclic high-energy fuels, and the yield of polycyclic high-energy fuels is high. In addition, water is used as a solvent, which is green and environmentally friendly. On the surface of the solid acid catalyst, water can become a proton donor / acceptor, and hydronium ions H3O + It can serve as the active site of the reaction. In addition, the presence of the water phase makes the polycyclic high-energy fuel and water a two-phase system, which is beneficial to the separation and purification of the product polycyclic high-energy fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The results of substrate conversion and selectivity of polycyclic high-energy fuels in the process of preparing polycyclic high-energy fuels in Examples 1-3 and Comparative Examples 1-3 are shown. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] In addition, in order to better illustrate the present application, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In some examples, methods and means well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present application.

[0027] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0028] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0029] The first aspect of the present invention provides a method for preparing a polycyclic high-energy fuel, the method comprising:

[0030] Using water as solvent, under the joint action of a metal catalyst and a solid acid catalyst, lignin-derived phenolic compounds are reacted in a hydrogen atmosphere to obtain the polycyclic high-energy fuel.

[0031] The present invention uses phenolic compounds as raw materials, which are selectively hydrogenated under the action of a metal catalyst to generate a cyclic alcohol intermediate, and the cyclic alcohol and phenols undergo an alkylation reaction under the action of the acidic site of a solid acid catalyst to obtain a polycyclic skeleton, and finally the metal catalyst and the acidic site in the solid acid catalyst synergistically catalyze a hydrogenation deoxygenation reaction to generate saturated polycyclic alkanes. Therefore, metal and solid acid are used as catalysts to achieve efficient conversion of lignin-derived phenolic compounds into polycyclic high-energy fuels, and the yield of polycyclic high-energy fuels is high. In addition, water is used as a solvent, which is green and environmentally friendly. On the surface of the solid acid catalyst, water can become a proton donor / acceptor, and hydronium ions H3O + It can serve as the active site of the reaction. In addition, the presence of the water phase makes the polycyclic high-energy fuel and water a two-phase system, which is beneficial to the separation and purification of the product polycyclic high-energy fuel.

[0032] In one embodiment, the metal catalyst comprises a supported metal catalyst, wherein the supported metal catalyst comprises a metal active site and a support, wherein the metal active site is supported on the support.

[0033] In one embodiment, the metal active site includes at least one of Pd, Pt, Ru and Rh, the support includes a porous material, and the support includes at least one of activated carbon, carbon nanotubes and mesoporous silica. Thus, the supported metal catalyst has excellent hydroalkylation effect.

[0034] In one embodiment, the content of the metal active sites is 0.1%-10% based on the total mass of the supported metal catalyst.

[0035] In one embodiment, the solid acid catalyst includes a zeolite molecular sieve having at least one structure of BETA, FAU and MWW. Thus, the solid acid catalyst has excellent hydrodeoxygenation effect; by using the above-mentioned zeolite molecular sieve with larger micropore diameter as a catalyst, on the one hand, it is conducive to the diffusion and mass transfer of lignin-derived phenolic compounds with larger molecular size and polycyclic oxygen-containing compounds (including cyclic alcohol intermediates, polycyclic skeletons, etc.) inside the molecular sieve pores, increasing their contact probability with acidic sites, and on the other hand, it is conducive to the diffusion of saturated polycyclic alkanes from the molecular sieve pores, promoting the forward reaction, thereby decomposing the problem of low polycyclic alkanes fuel yield.

[0036] In one embodiment, the solid acid catalyst includes at least one of Hβ, HY, USY, HX, MCM-22 and SSZ-25.

[0037] In one embodiment, the mass ratio of the lignin-derived phenolic compound, the mass of the metal catalyst, the mass of the solid acid catalyst and water is (2-50): (0.02-0.5): (1-15): (6-120). Relative to the above ratio range, when the content of the lignin-derived phenolic compound is low, the reaction substrate tends to be directly hydrodeoxygenated to obtain a monocyclic product, and the selectivity of the alkylation product is low; when the content of the lignin-derived phenolic compound is high, the concentration of the metal and the solid acid is not enough to promote the rapid reaction, resulting in a very low conversion rate of the substrate, thereby making the yield of the alkylation product low; when the content of the metal catalyst is low, it is not possible to obtain enough alcohol intermediates for alkylation reaction; when the content of the metal catalyst is high, the reaction is more inclined to excessive hydrodeoxygenation to obtain a monocyclic product; when the content of the solid acid catalyst is low, the amount of acid provided is insufficient to cause all alcohol intermediates to undergo alkylation reaction, resulting in a low selectivity for polycyclic products; when the content of the solid acid catalyst is high, it will also promote the deoxygenation reaction of the intermediate, and thus be more inclined to obtain a monocyclic alkane byproduct.

[0038] In one embodiment, the structural formula of the lignin-derived phenolic compound includes at least one of formula (1) to formula (3):

[0039]

[0040] Among them, R1 includes H, C n H 2n+1 , C n+1 H 2n+1 and (CH2) n-1 One of CHO, wherein n is an integer greater than or equal to 1 and not more than 3.

[0041] In one embodiment, the lignin-derived phenolic compound includes at least one of phenol, guaiacol, 2,6-dimethoxyphenol, vanillin, vanillone, gingerone, 4-ethylphenol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol, 4-acetoneguaiacol, 4-methyl-2,6-dimethoxyphenol, 2-methoxy-4-propylphenol, 4-hydroxy-3,5-dimethoxyacetophenone, syringaldehyde, eugenol, isoeugenol and 4-propylguaiacol.

[0042] In one embodiment, taking guaiacol as a reactant, the hydroalkylation reaction route to obtain a bicyclic product is as follows:

[0043]

[0044] In one embodiment, the reaction is carried out under stirring conditions and the reaction pressure is 5-7 MPa.

[0045] In one embodiment, water is used as a solvent, and under the combined action of a metal catalyst and a solid acid catalyst, a lignin-derived phenolic compound is reacted in a hydrogen atmosphere at a temperature of 110-240° C. (for example, 110° C., 150° C., 200° C., 220° C., or 240° C., etc.) for 2-48 hours (for example, 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, or 48 hours, etc.), and then the temperature is raised to 240-300° C. (for example, 240° C., 260° C., 280° C., or 300° C., etc.) and the reaction is continued for 2-48 hours (for example, 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, or 48 hours, etc.). Therefore, the above reaction includes two stages, the first stage is a hydroalkylation reaction, and the second stage is a hydrodeoxygenation reaction, which is conducive to obtaining a high-yield polycyclic high-energy fuel.

[0046] In one embodiment, the air in the solvent is replaced before the reaction, thereby avoiding interference of air on the reaction, reducing the probability of side reactions, and further improving the yield of polycyclic high-energy fuel.

[0047] The second aspect of the present invention provides a polycyclic high-energy fuel prepared by the above-mentioned preparation method, wherein the structural formula of the polycyclic high-energy fuel includes at least one of formula (4) to formula (11):

[0048]

[0049]

[0050] R2 includes H and / or C n H 2n+1 , n is an integer greater than or equal to 1 and not more than 3.

[0051] It can be understood that the polycyclic high-energy fuel may include one of formula (4) to formula (11), or may include two or more of formula (4) to formula (11). The density of the polycyclic high-energy fuel prepared using the compound represented by formula (2) as the raw material is 0.921 g / mL, and the calorific value is 42.98 MJ / kg; the density of the polycyclic high-energy fuel prepared using the compound represented by formula (1), the compound represented by formula (2) and the compound represented by formula (3) as the raw material is 0.910 g / mL, and the calorific value is 43.70 MJ / kg.

[0052] The present invention is further described below in conjunction with specific examples. It should be noted that the following examples are only used to explain the present invention and are not to be construed as limiting the present invention.

[0053] Example 1

[0054] The method for preparing the multi-ring high-energy fuel comprises the following steps:

[0055] 2.4 g of guaiacol, 12 g of water, 0.024 g of 5% Pd / C and 1.2 g of Hβ catalyst were added into a batch reactor. The air in the reactor was replaced by nitrogen and then filled with hydrogen. The magnetic stirring (800 rpm) was turned on and the temperature was programmed to rise to 200° C. (stage 1 temperature). The hydrogen pressure was maintained at 5 MPa. After reacting for 4 hours (stage 1), the temperature was raised to 260° C. (stage 2 temperature) and reacted for 4 hours (stage 2 time). The temperature was then lowered to room temperature. The obtained products were separated and qualitatively and quantitatively analyzed by gas chromatography-mass spectrometry and gas chromatography. The conversion rate of guaiacol was 97.6%, the selectivity of the product (polycyclic high-energy fuel) was 84.8%, and the yield was 82.7%.

[0056] Embodiment 2-9

[0057] The preparation methods of polycyclic high-energy fuels in Examples 2-9 are basically the same as those in Example 1, except for the selection of types and amounts of lignin-derived phenolic compounds (substrates), metal catalysts and solid acid catalysts, and the selection of parameters such as reaction temperature, reaction time, and hydrogen pressure, as shown in Table 1 below.

[0058] Table 1

[0059]

[0060]

[0061] Example 10

[0062] The composition of the lignin-derived phenolic compounds in this example is shown in Table 2 below:

[0063] Table 2

[0064]

[0065]

[0066] The composition of lignin-derived phenolic compounds in Table 2 simulated lignin pyrolysis oil as the reaction substrate.

[0067] The preparation method of the polycyclic high-energy fuel in this embodiment is basically the same as that in Embodiment 1, except that the lignin-derived phenolic compounds in Table 2 are used as substrates, and the types and amounts of metal catalysts and solid acid catalysts, reaction temperature, reaction time, hydrogen pressure and other parameters are selected as shown in Table 3 below:

[0068] Table 3

[0069]

[0070] From the above results, it can be seen that the synergistic system of metal catalysts and solid acid catalysts can well catalyze the hydroalkylation reaction of lignin-derived phenols such as phenol and guaiacol in the aqueous phase. The conversion rate of phenols such as guaiacol exceeds 95%, the selectivity of bicyclic and polycyclic products exceeds 75%, and the highest yield reaches 82.7%.

[0071] Comparative Example 1

[0072] The preparation method of the polycyclic high-energy fuel in this comparative example is basically the same as that in Example 1, except that the amount of the metal catalyst added is replaced by half of the original amount. In this comparative example, the substrate conversion rate is 32.7%, and the yield of the polycyclic high-energy fuel is 8.9%.

[0073] Comparative Example 2

[0074] The preparation method of the polycyclic high-energy fuel in this comparative example is basically the same as that in Example 1, except that the first-stage alkylation temperature is replaced with 100° C. In this comparative example, the substrate conversion rate is 10.6%, and the yield of the polycyclic high-energy fuel is 0.0%.

[0075] Comparative Example 3

[0076] The preparation method of the polycyclic high-energy fuel in this comparative example is basically the same as that in Example 1, except that the zeolite molecular sieve is replaced by HZSM-5. In this comparative example, the substrate conversion rate is 86.7%, and the yield of the polycyclic high-energy fuel is 0.8%.

[0077] The results of substrate conversion and selectivity of polycyclic high-energy fuels in the process of preparing polycyclic high-energy fuels in Examples 1-3 and Comparative Examples 1-3 are as follows: Figure 1 As shown, it can be seen that the effects of Examples 1 to 3 are much better than those of Comparative Examples 1 to 3. It can be seen that the amount of metal catalyst and the type of zeolite molecular sieve play a key role in the selectivity of polycyclic high-energy fuels and the conversion rate of substrates.

[0078] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0079] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for preparing a polycyclic high-energy fuel, characterized in that: include: Using water as solvent, under the joint action of a metal catalyst and a solid acid catalyst, lignin-derived phenolic compounds are reacted in a hydrogen atmosphere to obtain the polycyclic high-energy fuel.

2. The preparation method according to claim 1, characterized in that: The metal catalyst comprises a supported metal catalyst, wherein the supported metal catalyst comprises a metal active site and a carrier, wherein the metal active site is supported on the carrier; Preferably, the metal active site comprises at least one of Pd, Pt, Ru and Rh, and the support comprises a porous material; Preferably, the carrier comprises at least one of activated carbon, carbon nanotubes and mesoporous silica.

3. The preparation method according to claim 2, characterized in that: Based on the total mass of the supported metal catalyst, the content of the metal active sites is 0.1%-10%.

4. The preparation method according to claim 1, characterized in that: The solid acid catalyst comprises a zeolite molecular sieve having at least one structure of BETA, FAU and MWW; Preferably, the solid acid catalyst includes at least one of Hβ, HY, USY, HX, MCM-22 and SSZ-25.

5. The preparation method according to claim 1, characterized in that: The mass ratio of the lignin-derived phenolic compound, the mass of the metal catalyst, the mass of the solid acid catalyst and water is (2-50):(0.02-0.5):(1-15):(6-120).

6. The preparation method according to claim 1, characterized in that: The structural formula of the lignin-derived phenolic compound includes at least one of formula (1) to formula (3): Among them, R1 includes H, C n H 2n+1 , C n+1 H 2n+1 and (CH2) n-1 One of CHO, wherein n is an integer greater than or equal to 1 and not more than 3.

7. The preparation method according to claim 6, characterized in that: At least one of phenol, guaiacol, 2,6-dimethoxyphenol, vanillin, vanillone, gingerone, 4-ethylphenol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, 4-vinylguaiacol, 4-acetoneguaiacol, 4-methyl-2,6-dimethoxyphenol, 2-methoxy-4-propylphenol, 4-hydroxy-3,5-dimethoxyacetophenone, syringaldehyde, eugenol, isoeugenol and 4-propylguaiacol.

8. The preparation method according to claim 1, characterized in that: The reaction is carried out under stirring conditions, and the reaction pressure is 5-7MPa; Preferably, water is used as solvent, and under the combined action of a metal catalyst and a solid acid catalyst, the lignin-derived phenolic compound is reacted at 110-240° C. in a hydrogen atmosphere for 2-48 hours, and then the temperature is raised to 240-300° C. for further reaction for 2-48 hours.

9. The preparation method according to claim 1, characterized in that: Prior to the reaction, air in the solvent was replaced.

10. A multi-ring high-energy fuel prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The structural formula of the multi-ring high-energy fuel includes at least one of formula (4) to formula (11): R2 includes H and / or C n H 2n+1 , n is an integer greater than or equal to 1 and not more than 3.

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