Method for regulating and controlling propane catalytic performance and BTX yield

Abstract

The invention provides a method for regulating and controlling propane catalytic performance and BTX yield, which comprises the following specific steps: step S1, mixing a propane aromatization catalyst and quartz sand, filling the mixture into a reactor, and pretreating the catalyst; s2, providing a mixed raw material gas of propane and N2, and introducing the mixed raw material gas into the reactor filled with the mixture of the propane aromatization catalyst and the quartz sand in the step S1 under reaction conditions to carry out a propane aromatization reaction; according to the method, the catalyst is pretreated through one oxidizing or reducing gas or multiple oxidizing and reducing gases, and the reaction performance of the catalyst is tested, so that the optimal catalyst pretreatment mode is a pretreatment mode of oxidizing O2 and then reducing H2, the catalytic activity of the catalyst is improved, the propane aromatization performance and the BTX yield are further improved, and the cost is reduced. The method has high industrial value and economic value.

Description

Technical Field

[0001] The invention relates to the field of catalytic materials and efficient conversion and utilization of light aromatics, and in particular to a method for regulating propane catalytic performance and BTX yield. Background Art

[0002] Light aromatics (such as benzene, toluene, and xylene) are one of the most basic petrochemical raw materials. Aromatics are mainly derived from coal and oil. A variety of aromatics can be generated during coal distillation. With the rapid development of three major synthetic materials such as synthetic rubber, synthetic fiber, and synthetic resin, the demand for light aromatics has increased rapidly. In addition, light aromatics are also an important blending component of high-octane clean gasoline. Therefore, it is particularly important to develop new sources of aromatics and production technologies.

[0003] The reaction mechanism of propane aromatization is complex and involves multiple steps. First, propane molecules are adsorbed on the catalyst surface. Under the action of the metal active center, the C–C bond or C–H bond in the propane molecule breaks to generate small molecular products such as ethylene, propylene and hydrogen. The generated ethylene, propylene, etc. undergo polymerization reaction under the action of the catalyst acid site to form C 4 ~C 10 Olefins, these olefins are converted into corresponding dienes and alkanes through dehydrogenation reactions. Long-chain dienes undergo cyclization to form cyclic olefins such as cyclopentene and cyclohexene. This process requires the acidic sites of the catalyst to provide a suitable acidic environment to promote the reaction. Cyclic olefins such as cyclopentene and cyclohexene continue to undergo dehydrogenation reactions to form cyclic dienes. Cyclic dienes continue to dehydrogenate under the action of acidic sites, and eventually generate aromatic products such as benzene, toluene, and xylene. When the acidity of the active sites of the catalyst is too high, propane and its reaction intermediates may undergo deep dehydrogenation and polymerization reactions to generate highly unsaturated carbonaceous species. These carbonaceous species will gradually deposit on the catalyst surface to form carbon deposits. Carbon deposits will cover the active sites of the catalyst, block the pores of the catalyst, and make it difficult for reactants and products to adsorb and desorb on the catalyst surface, thereby reducing the activity and selectivity of the catalyst and shortening the service life of the catalyst. If the acidity of the catalyst is too strong, it may lead to an increase in side reactions such as excessive cracking, increase the content of low-carbon alkanes and olefins in the product, and reduce the selectivity of aromatics; if the acidity is too weak, the aromatization reaction rate will be slow and the aromatics yield will also be affected.

[0004] Therefore, developing a technology for improving the catalytic activity of propane aromatization catalyst and the yield of light aromatics in the propane aromatization reaction is an urgent problem to be solved. Summary of the invention

[0005] The object of the present invention is to provide a method for regulating the catalytic performance of propane and the yield of BTX by treating the catalyst with different oxidizing and / or reducing gases. By treating the catalyst with different oxidizing and / or reducing gases, the problem of low catalytic activity of the existing propane aromatization catalyst is solved, and the yield of light aromatics can be effectively improved.

[0006] Oxidizing atmosphere treatment will change the state of the active components of the catalyst, affecting the adsorption and activation of propane molecules; at the same time, it will change the properties of the catalyst carrier, thereby affecting the surface acidity. Reducing atmosphere treatment can reduce the oxidized active components to the metallic state, improve the activity of the catalyst, facilitate propane dehydrogenation and subsequent reactions, and provide suitable adsorption sites; it can also inhibit the formation of carbon deposits and extend the service life of the catalyst. Therefore, choosing a suitable atmosphere treatment method plays an important role in improving the catalytic performance of propane aromatization and increasing the yield of aromatics.

[0007] To achieve the above object, the present invention provides a method for regulating propane catalytic performance and BTX yield, and the specific steps are as follows:

[0008] Step S1, mixing a propane aromatization catalyst and quartz sand and loading the mixture into a reactor, and pretreating the catalyst, wherein the pretreatment is selected from one of oxidation pretreatment, reduction pretreatment, and redox pretreatment;

[0009] Step S2, providing propane and N 2 The mixed raw gas is introduced into the reactor filled with the propane aromatization catalyst and the quartz sand mixture in step S1 under reaction conditions to carry out propane aromatization reaction and test the catalytic performance.

[0010] Furthermore, the mass ratio of the propane aromatization catalyst to the quartz sand is 0.1-0.2 g:1-2 g.

[0011] Furthermore, the propane aromatization catalyst is selected from Ga-HZSM-5 catalyst or Ga 2 O 3 / One of the HZSM-5 catalysts.

[0012] Furthermore, the Ga content of the Ga-HZSM-5 catalyst is 1-2%, and the mass of the catalyst is 0.1-0.2 g.

[0013] Furthermore, the Ga 2 O 3 The Ga content of the HZSM-5 catalyst is 1-2%, and the mass of the catalyst is 0.1-0.2g.

[0014] Furthermore, the gas for oxidation pretreatment in step S1 is selected from CO 2 , one in the air.

[0015] Furthermore, the pre-reduction gas in step S1 is selected from H 2 One of the mixed gas of CO / Ar and CO / Ar.

[0016] Furthermore, the specific steps of the oxidation and / or reduction pretreatment in step S1 are as follows:

[0017] Step S11, Ga-HZSM-5 catalyst and Ga 2 O 3 / HZSM-5 catalysts are extruded and sieved to 40-60 meshes, 0.1-0.2g of the sieved catalyst is evenly mixed with 1-2g of quartz sand and then loaded into the constant temperature zone of a stainless steel fixed bed reactor with an inner diameter of 8mm; the 0.1-0.2g of the sieved catalyst is composed of Ga-HZSM-5 catalyst and Ga 2 O 3 / HZSM-5 catalyst is mixed in any proportion;

[0018] Step S12, the reactor is heated to 30-60 mL / min N 2 Raise the temperature to 550-600°C under atmosphere and keep the temperature constant;

[0019] Step S13, introducing 30 to 60 mL / min of different oxidizing and / or reducing gases into the reactor respectively, and subjecting the catalyst to oxidation and / or reduction treatment for 30 to 60 minutes.

[0020] Further, in step S2, propane and N 2 The volume ratio is 1~4:6~9.

[0021] Furthermore, the reaction conditions in step S2 include: the flow rate of the mixed feed gas flow is 20-50 mL / min, the reaction time is 3.5-6 h, and the reaction temperature is 550-600° C.

[0022] Compared with the prior art, the present invention is a processing method for regulating propane catalytic performance and BTX yield by changing the catalyst pretreatment atmosphere, pretreating the catalyst with an oxidizing or reducing gas or multiple oxidizing and reducing gases and testing its reaction performance, and obtaining the best catalyst pretreatment method is to firstly 2 After oxidation, H 2 The reduction pretreatment method improves the catalytic activity of the catalyst, thereby improving the propane aromatization performance and BTX yield, and has high industrial and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The propane conversion rate diagram of the Ga-HZSM-5 catalyst prepared in Examples 1-5 and Comparative Example 1 after being pretreated in different atmospheres;

[0024] Figure 2 The selectivity diagram of light aromatics of Ga-HZSM-5 catalysts prepared in Examples 1-5 and Comparative Example 1 after being pretreated in different atmospheres;

[0025] Figure 3 The light aromatics yields of the Ga-HZSM-5 catalysts prepared in Examples 1-5 and Comparative Example 1 after being pretreated in different atmospheres;

[0026] Figure 4 The Ga prepared in Examples 6-10 and Comparative Example 2 2 O 3 / Propane conversion diagram of HZSM-5 catalyst after pretreatment with different atmospheres;

[0027] Figure 5 The Ga prepared in Examples 6-10 and Comparative Example 2 2 O 3 / Light aromatics selectivity diagram of HZSM-5 catalyst after pretreatment with different atmospheres;

[0028] Figure 6 The Ga prepared in Examples 6-10 and Comparative Example 2 2 O 3 / The light aromatics yield of HZSM-5 catalyst after pretreatment with different atmospheres;

[0029] Figure 7 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 / SEM image of HZSM-5 catalyst;

[0030] Figure 8 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 HRTEM image and mapping image of / HZSM-5 catalyst;

[0031] Fig. 9 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 / XRD pattern of HZSM-5 catalyst. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0033] The technical solution of the present invention is further explained below in conjunction with implementation cases.

[0034] Example 1

[0035] This embodiment provides a method for regulating propane catalytic performance and BTX yield, including step S1 and step S2, and the specific steps are as follows:

[0036] Step S1: preparing a 1% Ga-HZSM-5 catalyst, the preparation method comprising the following steps:

[0037] Step S11, SiO 2 Measurement of water absorption:

[0038] Weigh three groups of 4.5g SiO 2 After drying in a 120°C blast oven for 12 h, the pretreated SiO 2 ,spare;

[0039] Weigh three groups of 4g pretreated SiO 2 Place them in eggplant-shaped flasks respectively. The eggplant-shaped flasks used have different masses. At this time, weigh the eggplant-shaped flasks and SiO 2 The total mass is 83.5g, 83.2g, and 52.008g (denoted as m 2 ).

[0040] Then deionized water was added dropwise, and the eggplant flask was shaken by hand at a rate of 60 rpm and a shaking time of 20 min. 2 When the adsorption saturation critical state is reached, stop adding dropwise. At this time, weigh the eggplant-shaped flask, SiO 2 The total mass of deionized water is 88.654g, 87.926g, and 56.558g (denoted as m 3 ),according to The water absorption rate c of the carrier was 6.8% as the average value obtained by measuring three times.

[0041] Step S12, preparing a gallium nitrate solution with a mass fraction of 1%:

[0042] SiO determined according to step S1 2 The volume of impregnation solution required for equal volume impregnation is calculated by the water absorption rate of 4g SiO 2 4.8 g of deionized water is needed), 0.242 g of gallium nitrate is dissolved in 4.8 g of deionized water to obtain a gallium nitrate solution with a mass fraction of 1%;

[0043] Step S13, preparing Ga by isovolumetric impregnation method 2 O 3 / SiO 2 As a silicon source:

[0044] 4 g of pre-treated SiO 2 Place it in an eggplant-shaped flask, and use a 50 ml pipette to evenly drop the 1% gallium nitrate solution prepared in step S12 onto the 4 g pretreated SiO 2 The eggplant-shaped flask was shaken by hand at a shaking rate of 60 rpm; the oscillation time was 20 min, and after standing for 24 h, it was placed in a 100°C oven to dry for 5 h. After drying, it was taken out and placed in a muffle furnace, and calcined at 500°C for 3 h to prepare Ga 2 O 3 / SiO 2 ;

[0045] Step S14, preparing Na-type ZSM-5 by hydrothermal method using tetrapropylammonium hydroxide / sodium hydroxide / silicon source / water:

[0046] Weigh 4.92 g of tetrapropylammonium hydroxide solution and 8.94 g of deionized water, mix and stir at room temperature for 0.5 h; then pour in 0.12 g of NaOH and stir again for 0.5 h; add 0.11 g of sodium aluminate to the solution and continue stirring at room temperature for 1 h; finally add the Ga prepared in step S13 2 O 3 / SiO 2 The silicon source was added and stirred for 12 hours to obtain a mixed solution; the mixed solution was poured into a hydrothermal reactor, and then placed in an oven for crystallization at 180°C for 24 hours; after the crystallization, the solution was centrifuged at a speed of 10000 rpm for 5 minutes and then placed in an oven at 80°C for drying for 5 hours. After drying, the solution was taken out and placed in a muffle furnace, and then calcined at 600°C for 6 hours to obtain a Na-type ZSM-5 molecular sieve;

[0047] Step S15, ion exchange, to prepare Ga-HZSM-5 catalyst:

[0048] Weigh the mass of Na-type ZSM-5 molecular sieve as 3g, place it in an eggplant-shaped flask, place the eggplant-shaped flask in a 90℃ oil bath, add 30ml of 1mol / l ammonium chloride solution to the eggplant-shaped flask for ion exchange and centrifugal drying, and obtain Ga-HZSM-5 catalyst. Perform ion exchange once, centrifugal drying once, centrifugal speed 10000 rpm, centrifugal 5min, centrifugal 3 times; after the ion exchange, place the clarified aqueous solution in an 80℃ oven for 2h, finally take it out after drying and place it in a muffle furnace, calcine at 600℃ for 6h, and obtain Ga-HZSM-5 catalyst.

[0049] Step S2: The Ga-HZSM-5 catalyst prepared in step S1 is used for a propane aromatization reaction and its performance is tested, which specifically includes the following steps:

[0050] 0.1 g of 40-60 mesh 1% Ga-HZSM-5 catalyst was uniformly mixed with 1 g of 40-60 mesh quartz sand and placed in a constant temperature zone of a stainless steel fixed bed reactor with an inner diameter of 8 mm for pretreatment. The pretreatment was specifically as follows: 2 The temperature was raised to 550°C in an atmosphere and oxidized at 550°C for 30 min in an air atmosphere at 30 mL / min. Then 20 mL / min of 40% C 3 H 8 / N 2 The mixed feed gas flow is contacted with a 1% Ga-HZSM-5 catalyst in a reactor to carry out an aromatization reaction at a reaction temperature of 600° C. and a reaction time of 5.5 h.

[0051] Example 2

[0052] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 1. The difference between this embodiment and Example 1 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550 °C under a 5% H atmosphere at 550 °C with a flow rate of 30 mL / min. 2 / Ar mixed gas (volume fraction) atmosphere for 30 min.

[0053] Example 3

[0054] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 1. The difference between this embodiment and Example 1 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550 °C under an atmosphere of 30 mL / min air at 550 °C for 30 min, and then the mixture was oxidized under an atmosphere of 30 mL / min N 2 The gas was purged for 5 min, followed by 5% H 2 / Ar mixed gas (volume fraction) atmosphere for 30 min.

[0055] Example 4

[0056] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 1. The difference between this embodiment and Example 1 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550 °C under a CO atmosphere and 30 mL / min CO 2 Oxidation under atmosphere for 30 min.

[0057] Example 5

[0058] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 1. The difference between this embodiment and Example 1 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550°C under an atmosphere of 5% CO / Ar and reduced at 550°C for 30 min at 30 mL / min.

[0059] Example 6

[0060] This embodiment provides a method for regulating propane catalytic performance and BTX yield, comprising step 1 and step 2;

[0061] Step 1: Preparation of 1% Ga 2 O 3 / HZSM-5 catalyst, the preparation method comprises the following steps:

[0062] Step 1.1, hydrothermally preparing Na-type ZSM-5 with tetrapropylammonium hydroxide / sodium hydroxide / silicon source / water, specifically comprising the following steps: weighing 4.92 g of tetrapropylammonium hydroxide solution and 8.94 g of deionized water, mixing, stirring at room temperature for 0.5 h; then pouring 0.12 g of NaOH, stirring again for 0.5 h; adding 0.11 g of sodium aluminate to the solution, stirring at room temperature for 1 h; finally adding the Ga prepared in step S13 of Example 1 2 O 3 / SiO 2 The silicon source is added and stirred for 12 hours to obtain a mixed solution; the mixed solution is poured into a hydrothermal reactor, and then placed in an oven for crystallization at 180°C for 24 hours; after the crystallization reaction is completed, the reactor is taken out of the oven, and the slurry after centrifugation is washed, dried and calcined at 600°C for 6 hours to obtain the Na-type ZSM-5 molecular sieve.

[0063] Step 1.2, carry out ion exchange in a 90°C oil bath with stirring, each time for 2 hours, for a total of 3 times. Specifically, the ion exchange is as follows: use a 1 mol / L ammonium chloride solution to carry out ammonium exchange on the Na-type ZSM-5 molecular sieve. 10 mL of ammonium chloride solution is required for 1 g of the catalyst. The ion exchange is performed once, and then centrifuged until the aqueous solution is clear and transparent, and then dried in an oven at 80°C for 2 hours. The ion exchange is repeated 3 times. Finally, after drying, the catalyst is taken out and placed in a muffle furnace, and calcined at 600°C for 6 hours to obtain a HZSM-5 catalyst.

[0064] Step 1.3, take the prepared HZSM-5 molecular sieve and place it in an eggplant-shaped flask. The water absorption rate of the HZSM-5 molecular sieve is determined by referring to the SiO 2Measurement of water absorption. According to the experimental determination of water absorption of HZSM-5 molecular sieve of 0.7%, 0.097g of gallium nitrate was dissolved in 0.56g of deionized water and evenly added to the HZSM-5 molecular sieve catalyst, and the mixture was shaken continuously at a rate of 60 rpm for 20 minutes to make it evenly mixed. The mixture was allowed to stand for 24 hours, dried for 5 hours, and then calcined in a muffle furnace at 600°C for 6 hours to obtain 1% Ga 2 O 3 / HZSM-5 catalyst.

[0065] Step 2: Ga prepared in step 1 2 O 3 The performance test of HZSM-5 catalyst used in propane aromatization reaction specifically includes the following steps:

[0066] 0.1g 40-60 mesh 1% Ga 2 O 3 The HZSM-5 catalyst was uniformly mixed with 1 g of quartz sand of 40-60 mesh and placed in a constant temperature zone of a stainless steel fixed bed reactor with an inner diameter of 8 mm for pretreatment. The pretreatment was specifically as follows: 2 The temperature was programmed to 550 °C under an atmosphere of 30 mL / min air at 550 °C for 30 min, with propane and N 2 The mixed feed gas flow was 20 mL / min 40% C 3 H 8 / N 2 The reaction was carried out by mixing the mixed feed gas flow with 1% Ga 2 O 3 / HZSM-5 catalyst was contacted to carry out aromatization reaction, the reaction temperature was 600°C, and the reaction time was 5.5h.

[0067] Example 7

[0068] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 6. The difference between this embodiment and Example 6 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550 °C under a 5% H atmosphere at 550 °C with a flow rate of 30 mL / min. 2 / Ar mixed gas (volume fraction) atmosphere for 30 min.

[0069] Example 8

[0070] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 6. The difference between this embodiment and Example 6 is that the pretreatment process is carried out at 30 mL / min N 2The temperature was programmed to 550 °C under an atmosphere of 30 mL / min air at 550 °C for 30 min, and then the mixture was oxidized under an atmosphere of 30 mL / min N 2 The gas was purged for 5 min, followed by 5% H 2 / Ar mixed gas (volume fraction) atmosphere for 30 min.

[0071] Example 9

[0072] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 6. The difference between this embodiment and Example 6 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550 °C under a CO atmosphere and 30 mL / min CO 2 Oxidation under atmosphere for 30 min.

[0073] Example 10

[0074] This embodiment also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 6. The difference between this embodiment and Example 6 is that the pretreatment process is carried out at 30 mL / min N 2 The temperature was programmed to 550°C under an atmosphere of 5% CO / Ar and reduced at 550°C for 30 min at 30 mL / min.

[0075] Comparative Example 1

[0076] This comparative example also provides a method for regulating the catalytic performance of propane and the yield of BTX. The specific method is referred to Example 1. The difference between this comparative example and Example 1 is that there is no step of oxidation at 550°C in an air atmosphere of 30 mL / min for 30 min. The pretreatment is specifically: 2 The temperature was raised to 550°C under the atmosphere, and then 20 mL / min of 40% C 3 H 8 / N 2 The mixed feed gas flow is contacted with a 1% Ga-HZSM-5 catalyst in a reactor to carry out an aromatization reaction at a reaction temperature of 600° C. and a reaction time of 5.5 h.

[0077] Comparative Example 2

[0078] This comparative example also provides a method for regulating propane catalytic performance and BTX yield. The specific method is referred to Example 6. The difference between this comparative example and Example 6 is that there is no step of oxidation at 550°C in 30 mL / min air atmosphere for 30 min. That is, the pretreatment is specifically: in 30 mL / min N 2The temperature was programmed to 550 °C under a propane and N atmosphere. 2 The mixed feed gas flow was 20 mL / min 40% C 3 H 8 / N 2 The reaction was carried out by mixing the mixed feed gas flow with 1% Ga 2 O 3 / HZSM-5 catalyst was contacted to carry out aromatization reaction, the reaction temperature was 600°C, and the reaction time was 5.5h.

[0079] The propane conversion rate is calculated from the mass of propane before and after the reaction, and the BTX selectivity is calculated by calculating the corresponding mass of each component. The specific calculation method is as follows:

[0080] The conversion rate is calculated as shown in formula (1.1):

[0081]

[0082] The product selectivity is calculated as shown in formula (1.2):

[0083]

[0084] Where m i is the mass of light aromatic hydrocarbons with carbon number i in the product, and i is the number of carbon atoms in the product.

[0085] The BTX yield is calculated as shown in formula (1.3):

[0086] Y=X·S×100% (1.3)

[0087] like Figures 1 to 3 As shown in Figure 2, compared with the untreated Ga-HZSM-5 catalyst, the conversion rate of propane by the Ga-HZSM-5 catalyst after oxidation pretreatment is greatly improved. 2 After oxidation, H 2 The reduction treatment method had the best effect, with the conversion rate up to 60%. The selectivity of Ga-HZSM-5 catalyst for BTX was greatly improved after being pretreated with different oxidizing or reducing gases, up to 45%. 2 Except for the Ga-HZSM-5 catalyst pretreated by reduction, which showed a slight decrease in the BTX yield, the other pretreated Ga-HZSM-5 catalysts showed a significant increase in the BTX yield. 2 After oxidation, H 2 The reduction treatment method has the best effect, with a maximum of 26%. Comprehensively considering the three indicators of propane conversion rate, BTX selectivity, and BTX yield, the first 2 After oxidation, H 2The catalyst pretreatment method of reduction has the greatest effect on improving catalyst performance. As the reaction time increases, the reaction activity of the catalysts after various pretreatments shows a decreasing trend. Considering various factors, the first 2 After oxidation, H 2 The reduced catalyst pretreatment method is the most active and stable.

[0088] like Figures 4 to 6 As shown, compared with the untreated Ga 2 O 3 / HZSM-5 catalyst, except for Ga after CO reduction 2 O 3 Except for a slight decrease in the conversion rate of propane over the pretreated Ga / HZSM-5 catalyst, the conversion rate of propane over the pretreated Ga 2 O 3 / HZSM-5 catalysts all improved the conversion of propane. 2 After oxidation, H 2 The reduction treatment method has the best effect, with the highest conversion rate reaching 46%. Combining the three indicators of propane conversion rate, BTX selectivity and BTX yield, the first O 2 After oxidation, H 2 The catalyst pretreatment method of reduction treatment has the greatest effect on improving catalyst performance. 2 After oxidation, H 2 The catalyst pretreatment method of reduction has the greatest effect on improving the propane catalytic performance and BTX yield. And as the reaction time increases, the difference between the initial conversion rate and the final conversion rate is small, which shows that the catalyst has good stability and slow deactivation rate.

[0089] Figure 7 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 / HZSM-5 catalyst SEM image; Ga-HZSM-5 catalyst SEM image as shown Figure 7 (a),Ga 2 O 3 SEM images of the / HZSM-5 catalyst are shown in Figure 7 (b) The SEM test was performed using a Zeiss SUPRA 55 scanning electron microscope produced by Zeiss of Germany. The sample morphology was tested at an operating voltage of 20 kV. The sample was sprayed with gold before the test. Figure 7 It can be seen that the surface of Ga-HZSM-5 catalyst particles is uneven, showing the morphology of rod-like structure aggregates. 2 O 3 The surface of the HZSM-5 catalyst particles is uneven, showing the morphology of nanoparticle aggregates.

[0090] Figure 8 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 HRTEM images and Mapping images of Ga-HZSM-5 catalysts; HRTEM images and Mapping images of Ga-HZSM-5 catalysts are shown in Figure 8 (a),Ga 2 O 3 HRTEM image and mapping image of / HZSM-5 catalyst are shown in Figure 8 (b) Transmission electron microscopy (TEM) and surface scanning (mapping) were performed using the FEI Talos F200X produced by Thermo Fisher Scientific. The operating voltage was 200 kV. Figure 8 It can be seen that the Si and Al elements of the two catalysts are evenly distributed. However, the Ga element distribution of the Ga-HZSM-5 catalyst is obviously better than that of the Ga 2 O 3 / HZSM-5 dispersion.

[0091] Fig. 9 The Ga-HZSM-5 catalyst prepared in Example 1 and Example 6 and the Ga 2 O 3 XRD patterns of / HZSM-5 catalysts. X-ray diffraction analysis (XRD) of the samples was performed using an Ultima IV X-ray diffractometer from Rigaku, Japan, with instrument parameters of 40 kV, 40 mA, Cu target, and Kα radiation. XRD patterns were collected in the 2θ range of 5 to 80° using a scan rate of 20° / min. Both catalysts were consistent with the ZSM-5 zeolite standard card (PDF#44-0003), indicating that the MFI structure was successfully synthesized, and no Ga was observed. 2 O 3 This may be because the Ga species is highly dispersed on the molecular sieve in a non-framework form, or it may be because the Ga content is too low to be detected. Fig. 9 It can be seen that the HZSM-5 catalyst shows typical MFI structural characteristic diffraction peaks, and the Ga-HZSM-5 (Si / Al=91) catalyst with the introduction of Ga species is basically consistent with the HZSM-5 diffraction pattern, with good crystallinity and no impurities, indicating that the introduction of Ga species will not change the skeleton structure of the molecular sieve.

[0092] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for regulating propane catalytic performance and BTX yield, characterized in that: The specific steps are as follows: Step S1, mixing a propane aromatization catalyst and quartz sand and loading the mixture into a reactor, and pretreating the catalyst, wherein the pretreatment is selected from one of oxidation pretreatment, reduction pretreatment, and redox pretreatment; Step S2, providing a mixed raw gas of propane and N2, and passing the mixed raw gas into the reactor filled with the propane aromatization catalyst and quartz sand mixture in step S1 under reaction conditions to carry out propane aromatization reaction.

2. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The mass ratio of propane aromatization catalyst to quartz sand is 0.1-0.2g:1-2g.

3. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The propane aromatization catalyst is selected from a Ga-HZSM-5 catalyst or a Ga2O3 / HZSM-5 catalyst.

4. The method for regulating propane catalytic performance and BTX yield according to claim 3, characterized in that: The Ga content of the Ga-HZSM-5 catalyst is 1-2%, and the mass of the catalyst is 0.1-0.2 g.

5. The method for regulating propane catalytic performance and BTX yield according to claim 3, characterized in that: The Ga2O3 / HZSM-5 catalyst has a Ga content of 1-2% and a catalyst mass of 0.1-0.2g.

6. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The gas for oxidation pretreatment in step S1 is selected from one of CO2 and air.

7. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The gas for reduction pretreatment in step S1 is selected from one of H2 / Ar mixed gas and CO / Ar mixed gas.

8. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The specific steps of oxidation and / or reduction pretreatment in step S1 are as follows: Step S11, extruding the Ga-HZSM-5 catalyst and the Ga2O3 / HZSM-5 catalyst respectively, sieving to 40-60 mesh, uniformly mixing 0.1-0.2 g of the sieved catalyst with 1-2 g of quartz sand, and then loading into the constant temperature zone of a stainless steel fixed bed reactor with an inner diameter of 8 mm; Step S12, heating the reactor to 550-600° C. in a N2 atmosphere at 30-60 mL / min, and maintaining the temperature constant; Step S13, introducing 30 to 60 mL / min of different oxidizing and / or reducing gases into the reactor respectively, and subjecting the catalyst to oxidation and / or reduction treatment for 30 to 60 minutes.

9. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The volume ratio of propane to N2 in step S2 is 1-4:6-9.

10. The method for regulating propane catalytic performance and BTX yield according to claim 1, characterized in that: The reaction conditions in step S2 include: the flow rate of the mixed feed gas flow is 20-50 mL / min, the reaction time is 3.5-6 h, and the reaction temperature is 550-600° C.

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