Method for preparing n-propylbenzene by taking n-nonane as raw material

Abstract

The invention provides a method for preparing n-propylbenzene by taking n-nonane as a raw material, and relates to the technical field of organic synthesis. The method comprises the following steps: carrying out aromatization reaction on gaseous n-nonane under the action of a catalyst to obtain n-propylbenzene; the catalyst comprises a molecular sieve and metal components loaded in a molecular sieve crystal, the metal components comprise a main metal and an auxiliary metal, the main metal comprises one or more of Pd, Pt and Rh, the auxiliary metal comprises one or more of Ag, Sn, Re and Zn, and the main metal and the auxiliary metal form an alloy sub-nanocluster. According to the method, high-selectivity preparation of the n-propylbenzene is realized by utilizing the low-price n-nonane, so that the low-value n-nonane is converted into the high-value n-propylbenzene in a high-selectivity manner, and a new way is opened up for efficient preparation of the n-propylbenzene. Results of the embodiment show that by adopting the method for preparing the n-propylbenzene, the conversion rate of the n-nonane is more than 80%, and the selectivity of the n-propylbenzene is more than 75%.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for preparing n-propylbenzene by using n-nonane as a raw material. Background Art

[0002] As an important aromatic hydrocarbon compound, n-propylbenzene's unique physical and chemical properties have demonstrated significant application value in numerous cutting-edge scientific fields. Recent systematic research has demonstrated breakthrough progress in the innovative application of this compound in materials engineering, energy storage, and biomedicine.

[0003] Currently, the main methods for producing n-propylbenzene include Friedel-Crafts alkylation, Clemmensen reduction, Grignard reagent, and alkylation of benzene with propylene. However, these methods suffer from expensive raw materials, resulting in high production costs for n-propylbenzene and limiting its widespread commercial application. Developing novel reaction pathways for the highly selective production of n-propylbenzene has significant research and practical value. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a method for preparing n-propylbenzene using n-nonane as a raw material. The present invention uses inexpensive n-nonane as a raw material to achieve highly selective preparation of n-propylbenzene, thereby reducing the production cost of n-propylbenzene.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing n-propylbenzene using n-nonane as a raw material, comprising the following steps:

[0007] The gaseous n-nonane is subjected to aromatization reaction under the action of a catalyst to obtain n-propylbenzene;

[0008] The catalyst includes a molecular sieve and a metal component loaded inside the molecular sieve crystals, the metal component includes a main metal and an auxiliary metal, the main metal includes one or more of Pd, Pt and Rh, the auxiliary metal includes one or more of Ag, Sn, Re and Zn, and the main metal and the auxiliary metal form alloy sub-nanoclusters.

[0009] Preferably, the molecular sieve comprises ZSM-5, Silicalite-1 or Beta molecular sieve.

[0010] Preferably, the mass percentage of the main metal and the auxiliary metal in the catalyst relative to the molecular sieve is independently 0.2-5%.

[0011] Preferably, the preparation method of the catalyst comprises the following steps:

[0012] Mixing a silicon / aluminum source, a template, water and sodium hydroxide to obtain a molecular sieve mother solution; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source;

[0013] Mixing the soluble precursor salt of the main metal, the soluble precursor salt of the co-metal, water and an organic amine ligand to obtain a metal complex solution;

[0014] The molecular sieve mother solution, the metal complex solution and ammonium chloride are mixed for hydrothermal crystallization, and the obtained crystallized product is sequentially calcined and reduced with hydrogen to obtain the catalyst.

[0015] Preferably, the silicon source includes silica sol and / or tetraethyl orthosilicate; the aluminum source includes one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate and sodium aluminate; and the template includes one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and triethylamine.

[0016] Preferably, the organic amine ligand includes one or more of dimethylethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine and 1,6-hexanediamine.

[0017] Preferably, the hydrothermal crystallization temperature is 150-180° C., and the time is 24-96 hours.

[0018] Preferably, the calcination temperature is 500-600° C., and the time is 3-5 h; the hydrogen reduction temperature is 500-550° C., and the time is 2-8 h.

[0019] Preferably, the aromatization reaction is carried out in a fixed bed reactor.

[0020] Preferably, the aromatization reaction temperature is 480-550°C, the pressure is 0.1-1.0 MPa, and the mass space velocity is 0.5-4 h -1 .

[0021] The present invention provides a method for preparing n-propylbenzene using n-nonane as a raw material, comprising the following steps: aromatizing gaseous n-nonane under the action of a catalyst to obtain n-propylbenzene; the catalyst comprises a molecular sieve and a metal component loaded inside the molecular sieve crystal, the metal component comprising a main metal and a co-metal, the main metal comprising one or more of Pd, Pt and Rh, the co-metal comprising one or more of Ag, Sn, Re and Zn, the main metal and the co-metal forming an alloy sub-nano cluster. In the present invention, the main metal (active metal) and the co-metal in the catalyst form an alloy sub-nano cluster, which is located inside the molecular sieve crystal and can catalyze the dehydrogenation of n-nonane to produce nonene, which undergoes cyclization and intracyclic dehydrogenation in the confined pores of the molecular sieve to produce n-propylbenzene with high selectivity. The present invention utilizes low-priced n-nonane to achieve highly selective preparation of n-propylbenzene, thereby converting low-value n-nonane into high-value n-propylbenzene with high selectivity, opening up a new approach for the efficient preparation of n-propylbenzene.

[0022] The results of the examples show that when n-propylbenzene is prepared by the method of the present invention, the conversion rate of n-nonane is greater than 80%, the selectivity of n-propylbenzene is greater than 75%, and the selectivity of total aromatics is greater than 83%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Pt prepared in Example 1 1.0 Ag 1.0 / Transmission electron microscopy image of ZSM-5 catalyst;

[0024] Figure 2 Pt prepared in Example 1 1.0 Ag 1.0 / Chart showing the catalytic effect of ZSM-5 catalyst in the aromatization reaction of n-nonane. DETAILED DESCRIPTION

[0025] The present invention provides a method for preparing n-propylbenzene using n-nonane as a raw material, comprising the following steps:

[0026] The gaseous n-nonane is subjected to aromatization reaction under the action of a catalyst to obtain n-propylbenzene;

[0027] The catalyst includes a molecular sieve and a metal component loaded inside the molecular sieve crystals, the metal component includes a main metal and an auxiliary metal, the main metal includes one or more of Pd, Pt and Rh, the auxiliary metal includes one or more of Ag, Sn, Re and Zn, and the main metal and the auxiliary metal form alloy sub-nanoclusters.

[0028] First, the catalyst will be described.

[0029] In the present invention, the catalyst comprises a molecular sieve and a metal component supported within the molecular sieve crystals. In the present invention, the molecular sieve preferably comprises ZSM-5, Silicalite-1, or Beta molecular sieve, which has a suitable microporous structure and confined environment, facilitating the aromatization reaction.

[0030] In the present invention, the metal component includes a main metal and a co-metal, the main metal includes one or more of Pd, Pt and Rh, and the co-metal includes one or more of Ag, Sn, Re (rhenium) and Zn; in an embodiment of the present invention, the main metal is Rh and the co-metal is Zn; or, the main metal is Pt and the co-metal is Ag or Re, preferably Ag. In the present invention, the main metal and the co-metal form alloy sub-nanoclusters, and the grain size of the alloy sub-nanoclusters is preferably 0.3 to 0.5 nm. The present invention uses the alloy sub-nanoclusters formed by the above-mentioned main metal and co-metal as the metal component of the catalyst, which can reduce the reaction energy barrier and improve the selectivity of the aromatic hydrocarbon n-propylbenzene and the stability of the catalyst.

[0031] In the present invention, the mass percentage of the primary metal and the co-metal relative to the molecular sieve in the catalyst is preferably independently 0.2-5%, and can be independently 0.3%, 0.5%, 1%, 1.5%, 2%, 3%, or 4%. Controlling the mass percentages of the primary metal and the co-metal within the above ranges facilitates the formation of a specific alloy structure and alloy ratio, thereby improving the activity and stability of the catalyst.

[0032] Compared to n-octane, n-nonane has a longer carbon chain and is more susceptible to high-temperature cracking reactions. Therefore, the selection of molecular sieve acidity and co-metal is significantly different from that of n-octane. The present invention utilizes a specific co-metal, supplemented by a molecular sieve with a high silicon-to-aluminum ratio (low acidity), to enhance the electron-donating capacity of the co-metal, reduce the cracking activity of n-nonane, and improve n-propylbenzene selectivity.

[0033] In the present invention, the preparation method of the catalyst preferably comprises the following steps:

[0034] Mixing a silicon / aluminum source, a template, water and sodium hydroxide to obtain a molecular sieve mother solution; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source;

[0035] Mixing the soluble precursor salt of the main metal, the soluble precursor salt of the co-metal, water and an organic amine ligand to obtain a metal complex solution;

[0036] The molecular sieve mother solution, the metal complex solution and ammonium chloride are mixed for hydrothermal crystallization, and the obtained crystallized product is sequentially calcined and reduced with hydrogen to obtain the catalyst.

[0037] In the present invention, unless otherwise specified, all raw materials involved are commercially available products well known in the art.

[0038] The present invention comprises mixing a silicon / aluminum source, a template, water, and sodium hydroxide to obtain a molecular sieve mother liquor; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source. In the present invention, the silicon source preferably comprises silica sol and / or tetraethyl orthosilicate (TEOS); the aluminum source preferably comprises one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate, and sodium metaaluminate; and the template preferably comprises one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and triethylamine.

[0039] In the present invention, the mass of the template is preferably 25% of the total mass of the template and water. In the present invention, when the silicon / aluminum source is a silicon source and an aluminum source, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is preferably greater than 80, the molar ratio of the template to the silicon source is preferably (0.1-0.4):1, and the molar ratio of sodium hydroxide to the silicon source is preferably (0.03-0.25):1. In the present invention, when the molecular sieve in the catalyst is a ZSM-5 molecular sieve, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is further preferably greater than 150, and can be 450-800, the molar ratio of the template to the silicon source is further preferably (0.1-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is further preferably (0.1-0.2):1; when the molecular sieve in the catalyst is a Beta molecular sieve, the molar ratio of the silicon source to the aluminum source in the molecular sieve mother liquor is further preferably greater than 100, and can be 300-400, the molar ratio of the template to the silicon source is further preferably (0.15-0.3):1, and the molar ratio of sodium hydroxide to the silicon source is further preferably (0.15-0.2):1. In the present invention, when the silicon / aluminum source is a silicon source, the molar ratio of the template to the silicon source in the molecular sieve mother liquor is preferably (0.1-0.4):1, and the molar ratio of sodium hydroxide to the silicon source is preferably (0.03-0.2):1. When the molecular sieve in the catalyst is a Silicalite-1 molecular sieve, the molar ratio of the template to the silicon source in the molecular sieve mother liquor is further preferably (0.25-0.4):1, and the molar ratio of sodium hydroxide to the silicon source is further preferably (0.1-0.2):1. When calculating the above molar ratios, the silicon source is calculated as SiO2, the aluminum source is calculated as Al, and the sodium hydroxide is calculated as Na.

[0040] In the present invention, the method of mixing the silicon / aluminum source, template, water and sodium hydroxide is preferably: mixing the template and water to obtain a template aqueous solution; adding the silicon / aluminum source to the template aqueous solution, stirring evenly, and then adding sodium hydroxide thereto and stirring evenly.

[0041] The present invention mixes a soluble precursor salt of the primary metal, a soluble precursor salt of the co-metal, water, and an organic amine ligand to obtain a metal complex solution. The present invention has no particular requirements for the types of the soluble precursor salt of the primary metal and the soluble precursor salt of the co-metal; these salts may be chlorates, chlorides, nitrates, or the like of the primary and co-metals. The organic amine ligand preferably includes one or more of dimethylethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, and 1,6-hexanediamine.

[0042] In the present invention, the mass of the primary metal element and the co-metal element in the metal complex solution is preferably 0.2-5% of the mass of the silicon source in the molecular sieve mother solution, and can be 0.3%, 0.5%, 1%, 1.5%, 2%, 3% or 4% of the mass of the silicon source in SiO2. In the present invention, the mass of the organic amine ligand is preferably 10-20 times the total mass of the primary metal element and the co-metal element.

[0043] In the present invention, the method of mixing the soluble precursor salt of the main metal, the soluble precursor salt of the auxiliary metal, water and the organic amine ligand is preferably: dissolving the soluble precursor salt of the main metal and the soluble precursor salt of the auxiliary metal in water, adding the organic amine ligand to the obtained mixed metal salt solution, and stirring evenly.

[0044] After obtaining the molecular sieve mother liquid and the metal complex solution, the present invention mixes the molecular sieve mother liquid, the metal complex solution and ammonium chloride for hydrothermal crystallization, and sequentially calcines and hydrogen reduces the obtained crystallized product to obtain the catalyst.

[0045] The present invention introduces metal elements in the form of metal complexes, facilitating the metal's entry into the molecular sieve crystals during crystallization. In the present invention, the molar ratio of ammonium chloride to the silicon source in the molecular sieve mother liquor is preferably (0.04-0.5):1, and may be 0.1:1, 0.2:1, or 0.3:1, with the silicon source being calculated as SiO2. The role of the ammonium chloride is to regulate the crystallization rate of the molecular sieve and the placement of the metal component, making it easier for the main metal to enter the micropores of the molecular sieve.

[0046] In the present invention, in the mixed solution obtained by mixing the molecular sieve mother liquor, the metal complex solution and ammonium chloride, the molar ratio of water to the silicon source is preferably greater than 18; when the molecular sieve in the catalyst is a ZSM-5 molecular sieve, the molar ratio of water to the silicon source in the mixed solution is further preferably greater than or equal to 21, and can be 21 to 24; when the molecular sieve in the catalyst is a Beta molecular sieve, the molar ratio of water to the silicon source in the mixed solution is further preferably greater than or equal to 20, and can be 20 to 21; when the molecular sieve in the catalyst is a Silicalite-1 molecular sieve, the molar ratio of water to the silicon source in the mixed solution is further preferably greater than or equal to 23, and can be 23 to 24; the silicon source is calculated as SiO2.

[0047] In the present invention, the method of mixing the molecular sieve mother liquor, the metal complex solution and ammonium chloride is preferably: adding the metal complex solution dropwise to the molecular sieve mother liquor, stirring evenly, and then adding ammonium chloride thereto, stirring evenly.

[0048] In the present invention, the temperature of the hydrothermal crystallization is preferably 150 to 180° C., and may be 150, 160, 170, or 180° C., and the time is preferably 24 to 96 hours, and may be 24, 36, 48, 72, or 96 hours. In the present invention, the crystallization reaction of the molecular sieve mainly occurs during the hydrothermal crystallization process. After the hydrothermal crystallization is completed, the resulting crystallization reaction solution is preferably filtered, solid-phase washed, and dried in sequence to obtain a crystallized product.

[0049] In the present invention, the calcination temperature is preferably 500-600°C, and can be 550 or 560°C. The calcination time is preferably 3-5 hours, and can be 3, 4, or 5 hours. The calcination is preferably carried out in air. During the calcination process, the template in the molecular sieve pores is removed, moisture is removed, and a high-temperature solid-state crystallization reaction of the molecular sieve occurs. Simultaneously, during the calcination process, the organic amine ligand undergoes decomposition and oxidation reactions to generate nitrogen oxides, the metal ions become oxides and are stored inside the molecular sieve crystals, and the ammonium chloride undergoes a decomposition reaction to form ammonia and hydrochloric acid, which enter the gas phase.

[0050] In the present invention, the temperature of the hydrogen reduction is preferably 500-550°C, and may be 510, 520, 530, 540, or 550°C. The temperature is preferably constant, and the heating rate from room temperature to the hydrogen reduction temperature is preferably 2-5°C / min. The hydrogen reduction time is preferably 2-8 hours, and may be 2, 3, 4, 5, or 8 hours. The hydrogen reduction is preferably carried out in a pure hydrogen atmosphere. During the hydrogen reduction process, the metal oxide inside the molecular sieve crystals is reduced to an alloy.

[0051] The present invention adopts a one-step direct synthesis method (i.e., mixing various raw materials and subjecting them to hydrothermal crystallization) to prepare the catalyst, which has a simple process, low cost, and is easy to scale up industrially.

[0052] In the present invention, the catalyst exhibits high activity and excellent stability. It can utilize inexpensive n-nonane to undergo dehydrogenation and cyclization (i.e., aromatization) within the micropores of the molecular sieve to produce n-propylbenzene, achieving highly selective production of n-propylbenzene. Example results demonstrate that in the reaction of n-nonane to produce n-propylbenzene, the catalyst exhibits high stability and selectivity, with a service life of over 850 hours.

[0053] The following describes a method for preparing n-propylbenzene using n-nonane as a raw material.

[0054] The present invention has no particular requirements for the source of the n-nonane; any source familiar to those skilled in the art (e.g., n-nonane extracted from naphtha) may be used. In the present invention, the gaseous n-nonane can be obtained by vaporizing the n-nonane. In the present invention, the aromatization reaction is preferably carried out in a fixed-bed reactor, i.e., the catalyst is loaded into the fixed-bed reactor, and the vaporized n-nonane enters the fixed-bed reactor for the aromatization reaction.

[0055] In the present invention, the temperature of the aromatization reaction is preferably 480-550°C, and may be 500, 510, 520 or 530°C; the pressure is preferably 0.1-1.0 MPa, and may be 0.1, 0.2, 0.3, 0.4, 0.5 or 1.0 MPa; and the mass space velocity is preferably 0.5-4 h -1 , which can be 1, 2, 3 or 4 hours -1 .

[0056] The present invention converts low-value n-nonane into high-value n-propylbenzene with high selectivity, thus opening up a new approach for the efficient preparation of n-propylbenzene.

[0057] In order to further illustrate the present invention, the method for preparing n-propylbenzene using n-nonane as a raw material provided by the present invention is described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] (a) 22.4 g of silica sol (30% by mass silica) and 0.03 g of aluminum nitrate were added to 24.0 g of a 25 wt% aqueous solution of tetrapropylammonium hydroxide, stirred until uniform, and then 0.8 g of sodium hydroxide was added. The mixture was stirred until uniform and then used.

[0060] (b) 0.180 g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.1066 g of silver nitrate (silver content 63.5%) were dissolved in 10 g of water, 2.5 g of dimethylethylenediamine was added thereto, and the mixture was stirred to form a transparent solution;

[0061] (c) adding the solution obtained in (b) dropwise to the mixed solution obtained in (a), stirring uniformly, and then adding 1.0 g of ammonium chloride, stirring uniformly;

[0062] (d) The sol obtained in (c) was transferred to a 100 mL crystallization reactor and crystallized at 170°C for 72 h, filtered, washed, dried at 100°C for 4 h, and then calcined at 560°C in air for 5 h. Before use, it was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 5°C / min from room temperature to 550°C and then reduced at constant temperature for 2 h to obtain Pt 1.0 Ag 1.0 / ZSM-5 finished catalyst (ie, the mass percentages of Pt and Ag in the catalyst relative to the ZSM-5 molecular sieve carrier are 1.0%, respectively).

[0063] Figure 1 Pt 1.0 Ag 1.0 / Transmission electron microscopy image of the ZSM-5 catalyst shows that the metal is evenly dispersed inside the crystals of the molecular sieve, forming sub-nanoclusters with a grain size of 0.3 to 0.5 nm.

[0064] Pt 1.0 Ag 1.0 / ZSM-5 catalyst was used for aromatization of n-nonane to produce n-propylbenzene. 1.0 Ag 1.0 The reaction was started by introducing the reaction raw material (gaseous n-nonane) into the ZSM-5 catalyst. The reaction conditions were: catalyst loading 2 g, reaction temperature 530 ° C, reaction pressure 0.3 MPa, reaction mass space velocity 2 h -1 Specific catalytic effect see Figure 2 and Table 1.

[0065] Depend on Figure 2 As can be seen from Table 1, the catalyst maintained good stability within 1100 h in the reaction of n-nonane to n-propylbenzene. The catalyst had excellent activity and high aromatics selectivity: the n-nonane conversion rate remained above 90%, the aromatics selectivity (in addition to n-propylbenzene, there were also by-products such as methylethylbenzene, ethylbenzene and toluene) was >80%, and the average n-propylbenzene selectivity was 76.6%.

[0066] Example 2

[0067] (a) 20.8 g of ethyl orthosilicate was added to 30.0 g of a 25 wt% aqueous solution of tetrapropylammonium hydroxide, stirred, and then 0.7 g of sodium hydroxide was added. The mixture was stirred for further use.

[0068] (b) 0.16 g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.188 g of ammonium perrhenate (rhenium content 64%) were dissolved in 20 g of water, 2.5 g of 1,4-butanediamine was added thereto, and the mixture was stirred to form a transparent solution;

[0069] (c) adding the solution obtained in (b) dropwise to the mixed solution obtained in (a), stirring uniformly, and then adding 0.85 g of ammonium chloride, stirring uniformly;

[0070] (d) The sol obtained in (c) was transferred to a 100 mL crystallization reactor and crystallized at 170 °C for 48 h, filtered, washed, dried at 100 °C for 4 h, and then calcined at 560 °C in air for 4 h. Before use, it was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 2 °C / min from room temperature to 550 °C and reduced at constant temperature for 3 h to obtain Pt 1.0 Re 2.0 / silicalite-1 finished catalyst (i.e., the mass percentage of Pt in the catalyst relative to the silicalite-1 molecular sieve carrier is 1.0%, and the mass percentage of Re relative to the silicalite-1 molecular sieve carrier is 2.0%).

[0071] Pt 1.0 Re 2.0 / silicalite-1 catalyst was used for the aromatization of n-nonane to produce n-propylbenzene. 1.0 Re 2.0 The reaction was started by introducing the raw material (gaseous n-nonane) into the silicalite-1 catalyst. The reaction conditions were: catalyst loading 2 g, reaction temperature 550 ° C, reaction pressure 0.5 MPa, reaction mass space velocity 2 h -1 The specific catalytic effects are shown in Table 1.

[0072] Example 3

[0073] (a) 20.8 g of silica sol (30% by mass silica) and 0.050 g of aluminum sulfate were added to 12.0 g of a 25 wt% aqueous solution of tetraethylammonium hydroxide, stirred, and then 0.7 g of sodium hydroxide was added. The mixture was stirred for further use.

[0074] (b) 0.084 g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.147 g of silver nitrate (silver content 63.5%) were dissolved in 15 g of water, 2.5 g of 1,4-butanediamine was added thereto, and the mixture was stirred to form a transparent solution;

[0075] (c) The solution obtained in (b) was added dropwise to the mixed solution obtained in (a), and stirred evenly. Then, 1.25 g of ammonium chloride was added and stirred evenly.

[0076] (d) The sol obtained in (c) was transferred to a 100 mL crystallization kettle and crystallized at 150 °C for 96 h, filtered, washed, dried at 100 °C for 4 h, and then calcined at 560 °C in air for 4 h. Before use, it was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 2 °C / min from room temperature to 550 °C and reduced at constant temperature for 4 h to obtain Pt 0.5 Ag 1.5 / Beta finished catalyst (i.e., the mass percentages of Pt and Ag in the catalyst relative to the Beta molecular sieve carrier are 0.5% and 1.5%, respectively).

[0077] Pt 0.5 Ag 1.5 / Beta catalyst was used in the aromatization reaction of n-nonane to produce n-propylbenzene. 0.5 Ag 1.5 The reaction was started by introducing the raw material (gaseous n-nonane) into the Beta catalyst. The reaction conditions were: catalyst loading 2 g, reaction temperature 530 ° C, reaction pressure normal pressure (0.1 MPa), reaction mass space velocity 1 h -1 The specific catalytic effects are shown in Table 1.

[0078] Example 4

[0079] (a) 22.4 g of silica sol (30% by mass silica fraction) and 0.02 g of sodium metaaluminate were added to 24.0 g of a 25 wt% aqueous solution of tetrapropylammonium hydroxide, stirred, and then 0.4 g of sodium hydroxide was added. The mixture was stirred for further use.

[0080] (b) 0.050 g of rhodium chloride trihydrate (rhodium content 40%) and 0.616 g of zinc nitrate hexahydrate (zinc content 21.8%) were dissolved in 15 g of water, 1.8 g of 1,3-propylenediamine was added thereto, and the mixture was stirred to form a clear solution;

[0081] (c) adding the solution obtained in (b) dropwise to the mixed solution obtained in (a), stirring uniformly, and then adding 0.8 g of ammonium chloride and stirring uniformly;

[0082] (d) The sol obtained in (c) was transferred to a 100 mL crystallization kettle and crystallized at 170°C for 48 h. It was filtered, washed, dried at 100°C for 4 h, and then calcined at 560°C in air for 4 h. Before use, it was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 2°C / min from room temperature to 550°C and reduced at constant temperature for 2 h to obtain Rh0.3 Zn 2.0 / ZSM-5 finished catalyst (ie, the mass percentages of Rh and Zn in the catalyst relative to the ZSM-5 molecular sieve carrier are 0.3% and 2.0%, respectively).

[0083] Rh 0.3 Zn 2.0 / ZSM-5 catalyst was used for aromatization of n-nonane to produce n-propylbenzene, and Rh 0.3 Zn 2.0 The reaction was started by introducing the reaction raw material (gaseous n-nonane) into the ZSM-5 catalyst. The reaction conditions were: catalyst loading 2 g, reaction temperature 500 ° C, reaction pressure 0.3 MPa, reaction mass space velocity 4 h -1 The specific catalytic effects are shown in Table 1.

[0084] Table 1 Catalytic effect of catalysts in Examples 1 to 4 for aromatization of n-nonane

[0085] Example Reaction life (h) Average conversion rate (%) Average aromatic selectivity (%) Average n-propylbenzene selectivity (%) 1 1100 92.7％ 84.8 76.6 2 1000 88.3％ 83.7 77.3 3 980 85.7％ 83.8 77.1 4 850 82.8％ 87.1 76.7

[0086] Comparative Example 1

[0087] The Pt prepared in Example 1 1.0 Ag 1.0 The ZSM-5 catalyst was used for the aromatization reaction of n-octane to produce ethylbenzene, except that n-nonane in Example 1 was replaced by n-octane, and the rest was the same as Example 1. The catalytic effect of Comparative Example 1 is shown in Table 2.

[0088] Table 2 Catalytic effect of the catalyst in Example 1 for n-octane aromatization reaction

[0089] Comparative Example Reaction life (h) Average conversion rate (%) Average aromatic selectivity (%) Average ethylbenzene selectivity (%) 1 280 52.7％ 54.8 28.6

[0090] Comparative Example 2

[0091] Pt was prepared by impregnation method 1.0 Ag 1.0 / ZSM-5 catalyst, the preparation method is as follows:

[0092] (a) 22.4 g of silica sol (30% by mass silica) and 0.03 g of aluminum nitrate were added to 24.0 g of a 25 wt% aqueous solution of tetrapropylammonium hydroxide, stirred until uniform, and then 0.8 g of sodium hydroxide was added. The mixture was stirred until uniform and then used.

[0093] (b) The sol obtained in (a) was transferred to a 100 mL crystallization kettle, crystallized at 170°C for 72 h, filtered, washed, and calcined at 560°C in air for 5 h before use;

[0094] (c) 0.180g of chloroplatinic acid hexahydrate (platinum content 37.5%) and 0.1066g of silver nitrate (silver content 63.5%) were dissolved in 10g of water, 2.5g of dimethylethylenediamine was added, and the mixture was stirred to form a transparent solution; the solution was impregnated into the sample obtained in (b), allowed to stand for 12h, dried at 100℃ for 5h, and calcined at 560℃ in air for 5h. Before use, the sample was activated by online reduction in a pure hydrogen atmosphere at a heating rate of 5℃ / min from room temperature to 550℃ and then reduced at constant temperature for 2h to obtain an impregnated Pt 1.0 Ag 1.0 / ZSM-5 finished catalyst (ie, the mass percentages of Pt and Ag in the catalyst relative to the ZSM-5 molecular sieve carrier are 1.0% respectively).

[0095] The Pt prepared by the impregnation method in Comparative Example 2 1.0 Ag 1.0 The / ZSM-5 catalyst was used for the aromatization reaction of n-nonane to prepare n-propylbenzene. The reaction conditions were the same as in Example 1. The catalytic effects are shown in Table 3.

[0096] Table 3 Comparative Example 2 Catalyst Pt 1.0 Ag 1.0 / Catalytic Effect of ZSM-5 on Aromatization of n-Nonane

[0097] Comparative Example Reaction life (h) Average conversion rate (%) Average aromatic selectivity (%) Average n-propylbenzene selectivity (%) 2 150 31.5％ 34.7 18.4

[0098] Comparative Example 3

[0099] The catalyst was obtained by omitting the ammonium chloride in Example 1 and remaining the same as in Example 1.

[0100] The catalyst obtained in Comparative Example 3 was used for the aromatization reaction of n-nonane to prepare n-propylbenzene. The reaction conditions were the same as those in Example 1. The catalytic effects are shown in Table 4.

[0101] Table 4 Catalytic effect of the catalyst of Comparative Example 3 for aromatization of n-nonane

[0102] Comparative Example Reaction life (h) Average conversion rate (%) Average aromatic selectivity (%) Average n-propylbenzene selectivity (%) 3 650 73.6％ 74.3 58.1

[0103] It can be seen from the above examples that the catalyst of the present invention has high activity and good stability, and the present invention achieves the high-selectivity conversion of low-value n-nonane into high-value n-propylbenzene.

[0104] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing n-propylbenzene using n-nonane as raw material, characterized in that: The following steps are involved: The gaseous n-nonane is subjected to aromatization reaction under the action of a catalyst to obtain n-propylbenzene; The catalyst includes a molecular sieve and a metal component loaded inside the molecular sieve crystals, the metal component includes a main metal and an auxiliary metal, the main metal includes one or more of Pd, Pt and Rh, the auxiliary metal includes one or more of Ag, Sn, Re and Zn, and the main metal and the auxiliary metal form alloy sub-nanoclusters.

2. The method according to claim 1, characterized in that The molecular sieve includes ZSM-5, Silicalite-1 or Beta molecular sieve.

3. The method according to claim 1, characterized in that The mass percentage of the main metal and the auxiliary metal in the catalyst relative to the molecular sieve is independently 0.2-5%.

4. The method according to claim 1 or 3, characterized in that The preparation method of the catalyst comprises the following steps: Mixing a silicon / aluminum source, a template, water and sodium hydroxide to obtain a molecular sieve mother solution; the silicon / aluminum source is a silicon source or a silicon source and an aluminum source; Mixing the soluble precursor salt of the main metal, the soluble precursor salt of the co-metal, water and an organic amine ligand to obtain a metal complex solution; The molecular sieve mother solution, the metal complex solution and ammonium chloride are mixed for hydrothermal crystallization, and the obtained crystallized product is sequentially calcined and reduced with hydrogen to obtain the catalyst.

5. The method according to claim 4, characterized in that The silicon source includes silica sol and / or tetraethyl orthosilicate; the aluminum source includes one or more of aluminum nitrate, aluminum hydroxide, aluminum sulfate and sodium metaaluminate; and the template includes one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and triethylamine.

6. The method according to claim 4, characterized in that The organic amine ligand includes one or more of dimethylethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine and 1,6-hexanediamine.

7. The method according to claim 4, characterized in that The temperature of the hydrothermal crystallization is 150-180° C., and the time is 24-96 hours.

8. The method according to claim 4, characterized in that The calcination temperature is 500-600° C., and the time is 3-5 hours; the hydrogen reduction temperature is 500-550° C., and the time is 2-8 hours.

9. The method according to claim 1, characterized in that The aromatization reaction is carried out in a fixed bed reactor.

10. The method according to claim 1 or 9, characterized in that The aromatization reaction temperature is 480-550° C., the pressure is 0.1-1.0 MPa, and the mass space velocity is 0.5-4 h -1 .

Images