Catalyst for preparing light aromatic hydrocarbon as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing light aromatic hydrocarbon as well as a preparation method and application of the catalyst. The catalyst comprises a metal oxide and a composite molecular sieve; the composite molecular sieve simultaneously comprises an eight-membered ring molecular sieve and a ten-membered ring molecular sieve; the acid amount of the weak acid of the eight-membered ring molecular sieve is 100-800 [mu] mol.g <-1 >, the acid amount of the strong acid of the eight-membered ring molecular sieve is 16-500 [mu] mol.g <-1 >, and the ratio of the acid amount of the weak acid to the acid amount of the strong acid is 1-6. The catalyst is applied to a reaction for preparing light aromatic hydrocarbon, and the selectivity of BTX in aromatic hydrocarbon is improved on the premise that the selectivity of total aromatic hydrocarbon is not reduced.

Description

Technical Field

[0001] The invention belongs to the field of light aromatic hydrocarbon catalysts, and in particular relates to a catalyst for preparing light aromatic hydrocarbons, a preparation method and an application thereof. Background Art

[0002] Synthesis gas is an important platform for producing chemicals instead of petroleum routes. It can be derived from natural gas, coal, biomass, etc. After different catalysts, synthesis gas can be used to produce oxygen-containing compounds, C 2 -C 4 Hydrocarbons, liquid fuels, aromatics and other basic chemicals with high added value. Among them, aromatic products, especially BTX, are raw materials for synthesizing styrene, polyamide resin, terephthalic acid, etc., which have important commercial value and have received widespread attention.

[0003] CN110368984A discloses an Fe-based catalyst and its preparation method and application in the one-step process of preparing aromatics from synthesis gas. The catalyst is composed of Fe-based spinel material, molecular sieve zeolite and metal oxide, wherein the content of Fe-based spinel is 9.95% to 79.95%, the zeolite molecular sieve is 20% to 90% and the oxide additive is 0.05% to 20%. The catalyst couples the synthesis gas to olefins and the olefin aromatization reaction to prepare aromatics, but its methane selectivity is relatively high, while the aromatics selectivity is relatively low, about 60%.

[0004] CN110201709A discloses a composite catalyst for directly producing high-value aromatics from synthesis gas. The catalyst is made by mechanically mixing metal oxides and nano HZSM-5 molecular sieves or metal-modified nano HZSM-5 molecular sieves; wherein the metal oxide is at least one of sodium, potassium, iron, and manganese oxides. The use of this catalyst can achieve the coupling of multi-stage reactions, effectively improve the driving force of intermediate reactions, increase the conversion efficiency of synthesis gas, reduce the occurrence of side reactions, and the CO conversion rate can reach 95%, but the selectivity of aromatics in organic products is low (<60%).

[0005] Although the prior art has been studied in the field of preparing aromatics from syngas, the selectivity of light aromatics (benzene, toluene, xylene, referred to as BTX) with large demand in the coupled system is low. Therefore, it is of great significance to further develop a catalyst with high activity and high BTX selectivity for preparing aromatics from syngas in one step. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a catalyst for preparing light aromatics, a preparation method and application thereof. The catalyst is applied to the reaction of preparing light aromatics from carbon oxides and hydrogen, and improves the selectivity of BTX in aromatics without reducing the selectivity of total aromatics.

[0007] The first aspect of the present invention provides a catalyst for preparing light aromatic hydrocarbons, the catalyst comprising a metal oxide and a composite molecular sieve; the composite molecular sieve comprises an eight-membered ring molecular sieve and a ten-membered ring molecular sieve; the eight-membered ring molecular sieve has a weak acid content of 100 to 800 μmol·g -1 , the amount of strong acid is 16~500μmol·g -1 , the ratio of weak acid amount / strong acid amount is 1 to 6.

[0008] According to the present invention, preferably, the amount of weak acid in the eight-membered ring molecular sieve is 100 to 800 μmol·g -1 , preferably 150 to 600 μmol·g -1 As a non-limiting example, the amount of weak acid can be 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800 μmol·g -1 Any value among others.

[0009] According to the present invention, preferably, the amount of strong acid in the eight-membered ring molecular sieve is 16 to 500 μmol·g -1 , preferably 50 to 400 μmol·g -1 As non-limiting examples, the amount of strong acid can be 16, 20, 60, 100, 150, 200, 250, 300, 350, 400, 450, 500 μmol·g -1 Any value among others.

[0010] According to the present invention, preferably, in the eight-membered ring molecular sieve, the ratio of weak acid amount / strong acid amount is 1 to 6, preferably 1 to 4. As a non-limiting example, the ratio of weak acid amount / strong acid amount can be any value of 1, 2, 3, 4, 5, 6, etc.

[0011] According to the present invention, the eight-membered ring molecular sieve comprises at least one of SAPO-18 and SAPO-17 molecular sieves. Preferably, the silicon-containing eight-membered ring molecular sieve SiO 2 / Al 2 O 3 The molar ratio is 0.2 to 1.8.

[0012] According to the present invention, the ten-membered ring molecular sieve has a two-dimensional (2D) or three-dimensional (3D) ten-membered ring channel, and more preferably is at least one of ZSM-5, ZSM-11, ZSM-12, MCM-22, Silicalite-1 and Silicalite-2.

[0013] According to the present invention, in the catalyst, the metal element of the metal oxide is selected from at least one of Cr, Zr, Mn, Ce, La, In, Ga and Zn; preferably at least one of Cr, Zr, Ce, Mn and Ga.

[0014] According to the present invention, in the catalyst, the mass ratio of the metal oxide to the molecular sieve is 0.05-10, preferably 1-5.

[0015] According to the present invention, in the catalyst, the mass ratio of the eight-membered molecular sieve to the ten-membered ring molecular sieve is 1:5 to 5:1.

[0016] The second aspect of the present invention provides a method for preparing the catalyst for preparing light aromatic hydrocarbons, comprising: mixing a composite molecular sieve and a metal oxide to obtain the catalyst.

[0017] According to the present invention, the mixing is a mechanical mixing method, preferably the following method is adopted, including: dispersing the metal oxide and the composite molecular sieve in a low-carbon alcohol solution, and ultrasonically treating, drying and calcining to obtain the catalyst.

[0018] According to the present invention, in the method for mixing composite molecular sieve and metal oxide, the low-carbon alcohol is an alcohol with less than six carbon atoms, preferably ethanol. The mass concentration of the low-carbon alcohol solution is 50% to 90%. The mass ratio of the low-carbon alcohol to the total mass of the metal oxide and the composite molecular sieve in step (1) is (1 to 10):1, preferably (2 to 5):1. The ultrasonic treatment conditions are as follows: the ultrasonic frequency is 10 to 40 kHz, the ultrasonic temperature is 30 to 50°C, and the ultrasonic time is 0.5 to 3 hours. The drying conditions are as follows: the drying temperature is 50 to 120°C, and the drying time is 2 to 12 hours. The roasting conditions are as follows: the roasting temperature is 400 to 600°C, and the roasting time is 3 to 8 hours.

[0019] According to the present invention, the acid treatment method of the octahedral molecular sieve can be adopted to soak the octahedral molecular sieve in an acid solution. The acid used can be at least one of nitric acid, oxalic acid and acetic acid, preferably acetic acid. The concentration of the acid solution is 0.1-3 mol / L. The mass ratio of the octahedral molecular sieve to the acid solution is 1:1-1:5. The acid treatment equipment is preferably a stainless steel pressure vessel lined with polytetrafluoroethylene. The pressure is not particularly limited and is autogenous pressure. The temperature of the acid treatment is 150-180°C and the time is 12-36h. The heating device can be an oven.

[0020] According to the present invention, in the preparation method of the catalyst for preparing light aromatic hydrocarbons, the metal oxide can be prepared by conventional methods, such as precipitation method, preferably co-precipitation. In the precipitation method, the metal source is a metal salt. Preferably, the metal salt is at least one of nitrate, acetate and sulfate. The precipitant includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate and ammonia water. In the precipitation method, the molar ratio of the metal source to the precipitant is 0.5-2. After the coprecipitation reaction, aging, drying and roasting steps can be performed to obtain the metal oxide. The aging conditions are: aging temperature of 40-80°C and aging time of 1-5h. The drying conditions are: drying temperature of 80-120°C and drying time of 8-12h. The roasting conditions are: roasting temperature of 400-600°C, roasting time of 1-4h, and roasting atmosphere of hydrogen and nitrogen mixed atmosphere, preferably the volume concentration of hydrogen in hydrogen and nitrogen mixed gas is 10%-30%.

[0021] The third aspect of the present invention provides the use of the catalyst in the reaction of preparing light aromatic hydrocarbons.

[0022] According to the present invention, in the application, the light aromatic hydrocarbons include at least one of benzene, toluene and xylene (BTX).

[0023] According to the present invention, in the application, the raw gas includes: carbon oxides and hydrogen. The carbon oxides include at least one of carbon monoxide and carbon dioxide, preferably carbon monoxide. The molar ratio of hydrogen to carbon oxides is 0.5 to 10:1, preferably 0.5 to 5:1.

[0024] According to the present invention, the reaction conditions are: reaction temperature 350-450°C, and / or, reaction pressure 1-10 MPa, and / or, the total volume space velocity of carbon oxides and hydrogen is 800-10000 h -1 The reaction device is a fixed bed.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The inventors have found that in the reaction of preparing light aromatics from carbon oxides and hydrogen, when using both eight-membered ring molecular sieves and ten-membered ring molecular sieves, the acid content of the eight-membered ring molecular sieve, especially the weak acid content and the strong acid content, is crucial to improving the selectivity of light aromatics. The inventors have further found that when the eight-membered ring weak acid content is 100-800 μmol·g -1 , the amount of strong acid is 16~500μmol·g -1When the ratio of weak acid amount to strong acid amount is 1 to 6, it is beneficial to convert active intermediates such as methoxy and methanol generated by carbon oxides and hydrogen on the surface of metal oxide to form olefins, desorb from the surface of molecular sieve, and avoid BTX generated in the pores of the ten-membered ring from further alkylation with active intermediates such as methoxy at the acidic sites on the outer surface of the ten-membered ring molecular sieve. It can significantly improve the selectivity of BTX in aromatics without reducing the selectivity of total aromatics.

[0027] 2. The preparation method of the present invention comprises: mixing a composite molecular sieve and a metal oxide to obtain the catalyst. The eight-membered ring molecular sieve needs to be treated with acid. By controlling the acid treatment conditions, the eight-membered ring molecular sieve has an appropriate acid distribution, which reduces the side reaction of hydrogenation of the intermediate at the acid site of the molecular sieve to generate alkanes. Further, in the preferred embodiment, SiO 2 / Al 2 O 3 The acid distribution can be adjusted by adjusting the molar ratio and acid treatment conditions.

[0028] 3. The catalyst of the present invention is applied to the reaction for preparing light aromatic hydrocarbons, and can significantly improve the selectivity of BTX in aromatic hydrocarbons without reducing the selectivity of total aromatic hydrocarbons. DETAILED DESCRIPTION

[0029] The present invention will be further described below through specific implementations. The embodiments are only partial conditions for processing to achieve this purpose, but the scope of the claims of the present invention is not limited by these embodiments.

[0030] In the present invention, NH 3 -TPD was used to determine the acidity and acid content of the sample. The test was carried out on a chemical adsorption instrument (Altamira AMI-3300). 100 mg of the catalyst was first heated from 30°C to 600°C at 10°C / min in a He atmosphere for 60 min, then cooled to 50°C and then heated with a 10% (by volume) NH 3 NH 3 、N 2 The mixed gas is adsorbed until saturated, and then switched back to He purge to remove the NH physically adsorbed on the surface. 3 Then the temperature was raised from 50°C to 600°C at 10°C / min, and TCD was used to detect NH 3 The concentration of NH 3 -In the TPD spectrum, the peaks at 100-250°C correspond to weak acid centers, and the peaks at 250-500°C correspond to strong acid centers. The acidity and acid amount are calculated based on the peak areas of the weak acid peak and the strong acid peak.

[0031] In the present invention, CO conversion, aromatics selectivity, and BTX / aromatics are all percentages calculated on a molar basis.

[0032] [Example 1]

[0033] Preparation of metal oxides:

[0034] MnO was prepared by precipitation method. 0.5 mol of manganese nitrate was weighed and dissolved in 1000 mL of distilled water, then 1.0 mol of sodium hydroxide was dissolved in 1000 mL of water, the two aqueous solutions were co-precipitated in parallel, aged at 80°C for 2 h, filtered and dried at 100°C for 12 h, and calcined at 500°C in an atmosphere of 10% hydrogen and nitrogen mixed gas for 1 h to obtain MnO oxide.

[0035] Preparation of ten-membered ring molecular sieve:

[0036] 0.27 g of aluminum isopropoxide was added to a solution containing 16.27 g of tetrapropylammonium hydroxide (25%) and 11.82 g of deionized water, and stirred at room temperature for 10 h. Then 13.89 g of tetraethyl orthosilicate was added to the mixed solution and stirred for 12 h. 5.01 g of urea was added to the above solution and then stirred for 1 h to form a molecular sieve mother solution. The composition (molar ratio) of the final reaction mixture was 1SiO 2 :0.01Al 2 O 3 :0.3TPAOH:20H 2 O: 1.25urea. The mother liquor was placed in a polytetrafluoroethylene-lined autoclave and hydrothermaled in an oven at 180°C for 48 hours. Centrifugal washing was performed until the supernatant was neutral, dried at 80°C for 12 hours, and calcined at 550°C for 5 hours to obtain ZSM-5 molecular sieve.

[0037] Preparation and acid treatment of eight-membered ring molecular sieves:

[0038] 27.4 g of boehmite (Al 2 O 3 , 74.6 wt%) was added to the 3 PO 4 The mixture was prepared by mixing 119.2 g of water (85 wt%) and stirring until it was homogeneous. Then, HCl solution (37 wt%), TEAOH (25 wt%) and silica sol were added, and the mixture was further stirred until it was homogeneous. The composition (molar ratio) of the final reaction mixture was 0.4 SiO 2 :0.33HCl:0.67(TEA) 2 O:Al 2 O 3 :P 2 O 5 :40H 2O. The reaction mixture was sealed in a stainless steel pressure vessel of polytetrafluoroethylene and heated in an oven at 170°C under autogenous pressure for 72h. The solid reaction product was recovered by filtration, washed with water, and dried at 100°C for 12h, and then heated to 550°C at 2°C / min and calcined for 5h to obtain SAPO-18 molecular sieve.

[0039] 10g SAPO-18 molecular sieve was placed in 10g acetic acid with a concentration of 1mol / L, sealed in a stainless steel pressure vessel with polytetrafluoroethylene, and heated in an oven at 160°C under autogenous pressure for 12h, and then centrifuged and washed to obtain low-acid SAPO-18 molecular sieve. The weak acid content of SAPO-18 molecular sieve is 407μmol·g -1 , the acidity of strong acid is 163μmol·g -1 , weak acid amount / strong acid amount = 2.5. SiO 2 / Al 2 O 3 The molar ratio is 0.4:1.

[0040] Preparation of catalyst:

[0041] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0042] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0043] [Example 2]

[0044] The preparation of MnO, ZSM-5 and SAPO-18 molecular sieves is the same as in Example 1. The acid treatment of SAPO-18 molecular sieve is the same as in Example 1.

[0045] Preparation of catalyst:

[0046] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of SAPO-18 molecular sieve were ground and mixed, and granulated to obtain the catalyst.

[0047] The catalyst was loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400° C. for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400° C., the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0048] [Example 3]

[0049] The preparation of MnO and ZSM-5 is the same as in Example 1.

[0050] Preparation and acid treatment of eight-membered ring molecular sieves:

[0051] 27.4 g of boehmite (Al 2 O 3 , 74.6 wt%) was added to the 3 PO 4 The mixture was prepared by mixing 119.2 g of water (85 wt%) and stirring until homogeneous. Then, HCl solution (37 wt%), TEAOH (25 wt%) and silica sol were added, and the mixture was further stirred until homogeneous. The composition (molar ratio) of the final reaction mixture was 0.8 SiO 2 :0.33HCl:0.67(TEA) 2 O:Al 2 O 3 :P 2 O 5 :40H 2 O. The reaction mixture was sealed in a stainless steel pressure vessel of polytetrafluoroethylene and heated in an oven at 170°C under autogenous pressure for 72h. The solid reaction product was recovered by filtration, washed with water, and dried at 100°C for 12h, and then heated to 550°C at 2°C / min and calcined for 5h to obtain SAPO-18 molecular sieve.

[0052] 10g SAPO-18 molecular sieve was placed in 10g acetic acid with a concentration of 1mol / L, sealed in a stainless steel pressure vessel with polytetrafluoroethylene, and heated in an oven at 160°C under autogenous pressure for 12h, and then centrifuged and washed to obtain low-acid SAPO-18 molecular sieve. The weak acid content of SAPO-18 molecular sieve is 400μmol·g -1 , the acid content of strong acid is 250 μmol·g -1 , weak acid amount / strong acid amount = 1.6. SiO 2 / Al 2 O 3 The molar ratio is 0.8:1.

[0053] Preparation of catalyst:

[0054] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0055] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0056] [Example 4]

[0057] The preparation of MnO and ZSM-5 is the same as in Example 1.

[0058] Preparation and acid treatment of eight-membered ring molecular sieves:

[0059] 27.4 g of boehmite (Al 2 O 3 , 74.6 wt%) was added to the 3 PO 4 The mixture was mixed with 119.2 g of water and stirred until homogeneous. Then, HCl solution (37 wt%), TEAOH (25 wt%) and silica sol were added and the mixture was further stirred until homogeneous. The composition (molar ratio) of the final reaction mixture was 1.5 SiO 2 :0.33HCl:0.67(TEA) 2 O:Al 2 O 3 :P 2 O 5 :40H 2 O. The reaction mixture was sealed in a stainless steel pressure vessel of polytetrafluoroethylene and heated in an oven at 170°C under autogenous pressure for 72h. The solid reaction product was recovered by filtration, washed with water, and dried at 100°C for 12h, and then heated to 550°C at 2°C / min and calcined for 5h to obtain SAPO-18 molecular sieve.

[0060] 10g SAPO-18 molecular sieve was placed in 10g acetic acid with a concentration of 1mol / L, sealed in a stainless steel pressure vessel with polytetrafluoroethylene, and heated in an oven at 160°C under autogenous pressure for 12h, and then centrifuged and washed to obtain low-acid SAPO-18 molecular sieve. The weak acid content of SAPO-18 molecular sieve is 400μmol·g -1 , the acidity of strong acid is 384μmol·g -1 , weak acid amount / strong acid amount = 1.04. SiO 2 / Al 2 O 3 The molar ratio is 1.5:1.

[0061] Preparation of catalyst:

[0062] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0063] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0064] [Example 5]

[0065] The preparation of MnO, ZSM-5 and SAPO-18 molecular sieves is the same as in Example 1.

[0066] The acid treatment of SAPO-18 molecular sieve is:

[0067] 10g SAPO-18 molecular sieve was placed in 10g acetic acid with a concentration of 0.1mol / L, sealed in a stainless steel pressure vessel with polytetrafluoroethylene, and heated in an oven at 180℃ under autogenous pressure for 30h, and then centrifuged and washed to obtain low-acid SAPO-18 molecular sieve. The weak acid content of SAPO-18 molecular sieve is 540μmol·g -1 , the acidity of strong acid is 142μmol·g -1 , weak acid amount / strong acid amount = 3.8.

[0068] The preparation and molding of the catalyst are the same as in Example 1.

[0069] The testing conditions of the catalyst are the same as those in Example 1.

[0070] The activity evaluation results are shown in Table 1.

[0071] [Example 6]

[0072] Preparation of Cr by precipitation method 2 O 3 Oxide. Weigh 0.5 mol of chromium nitrate and dissolve it in 1000 mL of distilled water, then dissolve 1.0 mol of sodium hydroxide in 1000 mL of water, co-precipitate the two aqueous solutions, age at 80°C for 2 hours, filter and dry at 100°C for 12 hours, and calcine at 500°C in a 10% hydrogen / nitrogen mixed gas atmosphere for 1 hour to obtain Cr 2 O 3 Oxide.

[0073] The preparation of ZSM-5 and SAPO-18 molecular sieves is the same as in Example 1. The acid treatment of SAPO-18 molecular sieve is the same as in Example 1.

[0074] Preparation of catalyst:

[0075] 1.0 g of the prepared Cr 2 O 3 The oxide and 0.5g ZSM-5 and 0.5g SAPO-18 molecular sieve were added to 5g ethanol solution with a mass concentration of 80%, ultrasonicated at an ultrasonic frequency of 10kHz and an ultrasonic water bath temperature of 60°C for 2h, dried at 80°C for 12h, and calcined at 500°C for 1h to obtain a catalyst for preparing light aromatics.

[0076] The testing conditions of the catalyst are the same as those in Example 1.

[0077] The activity evaluation results are shown in Table 1.

[0078] [Example 7]

[0079] Preparation of metal oxides:

[0080] GaMn oxide was prepared by precipitation method. 0.47 mol of manganese nitrate and 0.03 mol of gallium nitrate were weighed and dissolved in 1000 mL of distilled water, and then 1.0 mol of sodium hydroxide was dissolved in 1000 mL of water. The two aqueous solutions were co-precipitated in parallel, aged at 80°C for 2 h, filtered, dried at 100°C for 12 h, and calcined at 500°C in an atmosphere of 10% hydrogen and nitrogen mixed gas for 1 h to obtain GaMn oxide.

[0081] The preparation of ZSM-5 and SAPO-18 molecular sieves is the same as in Example 1. The acid treatment of SAPO-18 molecular sieve is the same as in Example 1.

[0082] Preparation of catalyst:

[0083] 1.0 g of the prepared GaMn oxide, 0.5 g of ZSM-5 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0084] The testing conditions of the catalyst are the same as those in Example 1.

[0085] The activity evaluation results are shown in Table 1.

[0086] [Example 8]

[0087] The preparation of MnO and SAPO-18 molecular sieve is the same as in Example 1. The acid treatment of SAPO-18 molecular sieve is the same as in Example 1.

[0088] Preparation of ten-membered ring molecular sieve:

[0089] 33.05g silica sol, 1.16g tetrabutylammonium bromide, and 20g deionized water were added to a beaker and mixed to form solution I. 2.26g aluminum sulfate, 2.54g sodium hydroxide, and 20g deionized water were added to form a uniform solution II. Under constant stirring, solution II was slowly added to solution I and continued to stir for 8 hours until uniform. The molar ratio of the obtained reaction mixture was 9.0Na 2 O:1.0Al 2 O 3 :100SiO 2 :0.53(TBA) 2 O:1300H 2 O. The obtained initial gel was transferred to a reactor with a polytetrafluoroethylene liner, sealed and placed in a hydrothermal synthesis oven, and crystallized by a two-stage method of first low temperature and then high temperature, that is, first at 90°C for 24 hours, then heated to 170°C and continued to be kept at the same temperature for 24 hours. After the reactor was cooled, the solid was separated from the mother liquor, and the solid was washed with deionized water to neutrality, dried at 120°C in air, and calcined at 550°C for 5 hours after 3 ammonium exchanges to obtain ZSM-11 molecular sieve.

[0090] Preparation of catalyst:

[0091] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-11 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0092] The testing conditions of the catalyst are the same as those in Example 1.

[0093] The activity evaluation results are shown in Table 1.

[0094] [Example 9]

[0095] The preparation of MnO and SAPO-18 molecular sieve is the same as in Example 1. The acid treatment of SAPO-18 molecular sieve is the same as in Example 1.

[0096] ZSM-12 with Si / Al (atomic ratio) of 50 was purchased from the Catalyst Factory of Nankai University.

[0097] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-12 and 0.5 g of SAPO-18 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0098] The testing conditions of the catalyst are the same as those in Example 1.

[0099] The activity evaluation results are shown in Table 1.

[0100] [Comparative Example 1]

[0101] The preparation of MnO is the same as in Example 1. The preparation of ZSM-5 is the same as in Example 1.

[0102] 1.0 g of the prepared MnO oxide and 1.0 g of ZSM-5 were placed in 5 g of 80% ethanol solution, ultrasonicated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60° C. for 2 h, dried at 80° C. for 12 h, and calcined at 500° C. for 1 h to obtain a catalyst for preparing light aromatics.

[0103] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0104] [Comparative Example 2]

[0105] The preparation of MnO was the same as in Example 1. The preparation and acid treatment of SAPO-18 molecular sieve were the same as in Example 1.

[0106] 1.0 g of the prepared MnO oxide and 1.0 g of SAPO-18 were added to 5 g of 80% ethanol solution, ultrasonicated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60° C. for 2 h, dried at 80° C. for 12 h, and calcined at 500° C. for 1 h to obtain a catalyst for preparing light aromatics.

[0107] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0108] [Comparative Example 3]

[0109] The preparation of MnO is the same as in Example 1. The preparation of ZSM-5 is the same as in Example 1.

[0110] SSZ-13 was produced by Nankai University Catalyst Factory, with a Si / Al molar ratio of 25. The weak acid content was 240 μmol·g -1 , the acid content of strong acid is 570μmol·g -1 , weak acid amount / strong acid amount = 0.42.

[0111] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of SSZ-13 molecular sieve were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0112] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0113] [Comparative Example 4]

[0114] The preparation of MnO is the same as in Example 1.

[0115] The preparation of ZSM-11 is the same as in Example 8.

[0116] The preparation of ZSM-5 is the same as in Example 1.

[0117] 1.0 g of the prepared MnO oxide, 0.5 g of ZSM-5 and 0.5 g of ZSM-11 molecular sieves were placed in 5 g of 80% ethanol solution, ultrasonically treated at an ultrasonic frequency of 10 kHz and an ultrasonic water bath temperature of 60°C for 2 h, dried at 80°C for 12 h, and calcined at 500°C for 1 h to obtain a catalyst for preparing light aromatics.

[0118] The obtained catalyst was granulated and loaded into a quartz reaction tube with an inner diameter of 6 mm. Before the reaction, it was reduced with hydrogen at 400°C for 3 hours. After the reduction was completed, the raw gas (n hydrogen: n carbon monoxide = 50:50) was introduced into the reaction tube and entered the catalyst bed for reaction. The reaction temperature was 400°C, the reaction system pressure was 5 MPa, and the volume space velocity of the raw gas was 2000 h -1 The syngas to aromatics reaction was carried out under the following conditions. The activity evaluation results are shown in Table 1.

[0119] [Comparative Example 5]

[0120] The preparation of MnO, ZSM-5, and SAPO-18 molecular sieves is the same as in Example 1. The difference is that the SAPO-18 molecular sieve is not acid-treated. The weak acid amount of the SAPO-18 molecular sieve in this example is 1230 μmol·g -1 , the acidity of strong acid is 182μmol·g -1 , weak acid amount / strong acid amount = 6.8.

[0121] The preparation and molding of the catalyst are the same as in Example 1.

[0122] The testing conditions of the catalyst are the same as those in Example 1.

[0123] The activity evaluation results are shown in Table 1.

[0124] Table 1

[0125]

[0126]

[0127] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst for preparing light aromatic hydrocarbons, comprising a metal oxide and a composite molecular sieve; the composite molecular sieve comprises an eight-membered ring molecular sieve and a ten-membered ring molecular sieve; the eight-membered ring molecular sieve has a weak acid content of 100 to 800 μmol·g -1 , the amount of strong acid is 16~500μmol·g -1 , the ratio of weak acid amount / strong acid amount is 1 to 6.

2. The catalyst according to claim 1, characterized in that In the eight-membered ring molecular sieve, the amount of weak acid is 150 to 600 μmol·g -1 , the amount of strong acid is 50~400μmol·g -1 , the ratio of weak acid amount / strong acid amount is 1 to 4.

3. The catalyst according to claim 1, characterized in that The eight-membered ring molecular sieve includes at least one of SAPO-18 and SAPO-17 molecular sieves.

4. The catalyst according to claim 1, characterized in that The ten-membered ring molecular sieve is at least one of ZSM-5, ZSM-11, ZSM-12, MCM-22, Silicalite-1 and Silicalite-2; and / or the mass ratio of the eight-membered molecular sieve to the ten-membered ring molecular sieve is 1:5 to 5:

1.

5. The catalyst according to claim 1, characterized in that The metal element of the metal oxide is selected from at least one of Cr, Zr, Mn, Ce, La, In, Ga and Zn; preferably at least one of Cr, Zr, Ce, Mn and Ga; and / or the mass ratio of the metal oxide to the molecular sieve is 0.05 to 10, preferably 1 to 5.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising: The composite molecular sieve and the metal oxide are mixed to obtain the catalyst.

7. The preparation method according to claim 6, characterized in that: The mixing is a mechanical mixing method; preferably, the following method is adopted, including: dispersing the metal oxide and the composite molecular sieve in a low-carbon alcohol solution, and ultrasonically treating, drying and calcining to obtain the catalyst.

8. The preparation method according to claim 6, characterized in that: The eight-membered ring molecular sieve needs to be treated with acid; preferably, the temperature of the acid treatment is 150 to 180° C. and the time is 12 to 36 hours.

9. The preparation method according to claim 8, characterized in that: The acid used includes at least one of nitric acid, oxalic acid and acetic acid, preferably acetic acid; further, the concentration of the acid solution is 0.1-3 mol / L.

10. Use of the catalyst according to any one of claims 1 to 5 or the catalyst prepared by the preparation method according to any one of claims 6 to 9 in the reaction of preparing light aromatic hydrocarbons.

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