CN110694675A - Catalyst for efficiently synthesizing p-xylene by low-carbon hydrocarbon shape-selective aromatization - Google Patents
Catalyst for efficiently synthesizing p-xylene by low-carbon hydrocarbon shape-selective aromatization Download PDFInfo
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- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/405—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing rare earth elements, titanium, zirconium, hafnium, zinc, cadmium, mercury, gallium, indium, thallium, tin or lead
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- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
- B01J29/46—Iron group metals or copper
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
- C07C2/76—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen
- C07C2/82—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen oxidative coupling
- C07C2/84—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen oxidative coupling catalytic
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
- B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
- C07C2529/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11 containing iron group metals, noble metals or copper
- C07C2529/46—Iron group metals or copper
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
- C07C2529/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
A catalyst for high-efficiency synthesis of p-xylene by low-carbon hydrocarbon shape-selective aromatization comprises a short-pore HZSM-11 molecular sieve with a special shape, a binder and a modification auxiliary agent. Wherein the weight part ratio of the short-pore HZSM-11 molecular sieve with special morphology to the binder is 50-95 wt% and 5-50 wt%, respectively; the content of the modified auxiliary agent is 0.1-30 wt% of the total weight of the molecular sieve and the binder. The catalyst is prepared based on the molding of a short-pore HZSM-11 molecular sieve with a special morphology and the modification of at least one oxide auxiliary agent, and is applied to the reaction for producing p-xylene by low-carbon hydrocarbon aromatization. Compared with the prior catalyst technology, the catalyst of the invention is a short pore path shape selective catalyst, and particularly has high aromatization efficiency and can effectively inhibit benzene, toluene, o/m-xylene and C9+The generation of byproducts such as aromatic hydrocarbon and the like shows extremely high selectivity and yield of p-xylene.
Description
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to a catalyst for efficiently synthesizing paraxylene by low-carbon hydrocarbon shape-selective aromatization and an application method thereof.
Background
Para-xylene (PX) is one of the most demanding basic aromatic feedstocks today, and is oxidized to produce terephthalic acid, which can be further synthesized into important high molecular weight polyester fibers and plastics. In addition, it is widely used in the fields of medicines, agricultural chemicals, dyes, solvents, and the like. In recent years, with the continuous high-speed development of the polyester industry and the fine chemical industry, the demand for PX is rapidly increasing year by year. According to statistics, the annual PX demand in China currently reaches more than 2000 million tons, and about 1200 million tons need to be imported. The main commercial production methods are toluene disproportionation and xylene isomerization separation, which have the problems of low raw material utilization rate and low para-xylene yield, respectively. Therefore, developing new PX stimulation techniques is particularly important to solve the problem of insufficient long-term productivity.
C4～C6Lower hydrocarbon and hydrocarbon containing C4～C6The mixed hydrocarbon of low carbon hydrocarbon is the by-product of petrochemical and coal chemical industry, mainly produced in the production process of ethylene engineering, oil refining, coal chemical products, etc. Particularly, with the continuous and rapid development of modern coal chemical industry in recent years, the yield of low-carbon mixed hydrocarbon is rapidly increased. Besides a few hydrocarbon components extracted to be used as chemical raw materials, most of the low-carbon hydrocarbon components are used as cheap fuel for treatment in the form of mixture, and the waste of carbon and hydrogen resources is realized from the viewpoint of efficient and reasonable utilization of fossil energy. Therefore, how to convert these byproducts into high value-added chemicals has become a focus of attention. The synthesis route for converting the low-carbon hydrocarbon into the aromatic hydrocarbon through aromatization catalytic reaction not only can open up a new raw material source for the production of aromatic hydrocarbon chemicals such as paraxylene, but also can optimize and utilize light hydrocarbon resources and improve the economic benefit of enterprises, and is focused by people.
The aromatization of the low-carbon hydrocarbon is a complex process comprising the reaction steps of dehydrogenation, oligomerization, cyclization, hydrogen transfer and the like, and the development of a catalyst with excellent performance is crucial. The reported catalysts include two broad classes, namely metal supported and modified molecular sieve types. The latter type has higher aromatization efficiency due to the existence of surface acidity of the molecular sieve and the concerted catalysis of the molecular sieve and the active sites of the metal. The ten-membered-ring microporous molecular sieve has the channel size close to the molecular dynamic size of light aromatic hydrocarbon and is considered to be a molecular sieve catalytic material suitable for light hydrocarbon aromatization reaction. In particular, the aromatization efficiency can be obviously improved by adopting the modification of metal species of Zn, Ga, Ag, Mo, Ni and the like. However, C tends to be present in the aromatic product9+Aromatic hydrocarbons, o/m-xylene, benzene, toluene, etc., resulting in low selectivity and yield of p-xylene. For example, the patent CN109465022A discloses a Zn, Ga and Ni composite modified HZSM-5 molecular sieve, which is applied to aromatization reaction of light hydrocarbon byproduct in Fischer-Tropsch synthesis catalysis, although the total yield of aromatic hydrocarbon is remarkably improved to 58.1% at most, the yield of paraxylene is lower than 4%. In the light hydrocarbon aromatization technology using the metal modified HZSM-5 and the metal modified HMOR two-stage catalyst bed disclosed in the patent CN102030605A, the final total yield of the aromatic hydrocarbon can reach 53.85 percent at most, but the yield of the p-xylene is lower than 5.5 percent. In general, the technical economy of the light hydrocarbon aromatization conversion route is not high due to the generally low selectivity of high value-added products to the paraxylene, which hinders the wide-range industrial application thereof.
Disclosure of Invention
The invention aims to provide a catalyst for efficiently synthesizing paraxylene by low-carbon hydrocarbon shape-selective aromatization and an application method thereof, which are used for solving the problem of low selectivity of paraxylene in the existing low-carbon hydrocarbon aromatization catalytic reaction in the background technology.
In order to achieve the aim, the invention provides a catalyst for efficiently synthesizing paraxylene by low-carbon hydrocarbon shape-selective aromatization, which is characterized in that the composition of the catalyst comprises a short-pore HZSM-11 molecular sieve with a special shape, a binder and a modification auxiliary agent; wherein the weight part ratio of the short-pore HZSM-11 molecular sieve with special morphology to the binder is 50-95 wt% and 5-50 wt%, respectively; the content of the modified auxiliary agent is 0.1-30 wt% of the total weight of the molecular sieve and the binder.
In a specific embodiment, the short-pore HZSM-11 molecule with special morphology is selected from one or a mixture of two of nano flaky HZSM-11 with the flaky crystal thickness of 2-350 nm and nano needle-shaped HZSM-11 with the needle-shaped crystal section diameter of 2-450 nm.
In a specific embodiment, the special morphology short pore HZSM-11 molecular sieve has a silicon-aluminum atom molar ratio of 2-500.
In a particular embodiment, the binder is selected from alumina or silica.
In a specific embodiment, the modification aid is selected from oxides of one or more elements of lanthanum, silicon, calcium, boron, phosphorus, magnesium, nickel, copper, zinc, gallium, molybdenum, silver.
In a specific embodiment, the catalyst is in the form of a rod or sphere.
In one specific embodiment, the operating conditions for the catalyst to be applied to catalyze the shape-selective aromatization of lower hydrocarbons to paraxylene are as follows: the mass space velocity of the low-carbon hydrocarbon is 0.1-20 h-1The reaction pressure is 0.1-5 MPa, and the reaction temperature is 300-700 ℃.
In a specific embodiment, the lower hydrocarbon comprises C3～C6Alkanes and dilute hydrocarbons.
In a specific embodiment, the low-carbon hydrocarbon includes refinery gas, light gasoline, oil gas light hydrocarbon and light hydrocarbon by-produced in the process of making chemicals from coal, and the aromatization catalytic reaction applied to the catalyst adopts a fixed bed reactor, a moving bed reactor or a fluidized bed reactor.
Compared with the prior art, the invention has the following beneficial effects:
the invention is prepared based on the molding of short-hole HZSM-11 with special morphology and the modification of at least one oxide auxiliary agent. It is characterized in that the catalyst has high aromatization efficiency and can effectively inhibit benzene, toluene, o/m-xylene and C9+Aromatic hydrocarbon and other by-products are generated, and high selectivity and yield of p-xylene are shown.
The traditional metal modified ten-membered-ring microporous molecular sieve catalyzes the aromatization reaction process of the low-carbon hydrocarbonOn one hand, due to the existence of the acidity of the outer surface, the p-xylene generated by the reaction in the pore canal diffuses to the outer surface to generate deep alkylation and isomerization reactions to generate C9+Aromatic hydrocarbons and ortho/meta xylene by-products; on the other hand, because the aromatization active site is often a stronger acid center and the diffusion path of micropores in the traditional molecular sieve is longer, the diffusion residence time of the product p-xylene in the micropores is longer, the demethylation reaction is easy to generate toluene and benzene byproducts, and finally the selectivity of the p-xylene is very low. In the invention, at least one metal oxide is adopted to modify and modify the formed short-pore HZSM-11 molecular sieve with special morphology to obtain the catalyst, the active sites on the outer surface are selectively eliminated, simultaneously, the pore openings of the micropores are properly reduced, but the reactive sites in the pores are reserved, and the catalyst also has an obviously shorter reaction path of micropore diffusion in the crystal. The shape-selective micropore can realize the product shape-selective of the para-isomer of the xylene, and effectively prevent the para-xylene diffused in the shape-selective micropore from generating side reactions of isomerization and deep alkylation on the outer surface of the catalyst; the para-xylene molecules generated in the pores can be diffused away from the catalyst more quickly, the deep demethylation of the para-xylene molecules is effectively avoided to generate benzene and toluene, and the forward movement of reaction balance is promoted to improve the aromatization efficiency. Therefore, the low-carbon hydrocarbon shape-selective aromatization catalyst has higher selectivity and yield of p-xylene than the conventional catalyst, and can effectively improve the technical economy of the synthesis route.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below.
Detailed Description
The invention is described in detail below with reference to specific examples, but it can be implemented in many different ways as defined and covered by the claims.
Example 1
1) 10g of nano flaky HZSM-11 molecular sieve with 90nm of flaky crystal thickness and 7 of silicon-aluminum atom molar ratio and 10g of alumina binder are mixed, stirred uniformly, dropwise added with a proper amount of dilute nitric acid for kneading, extruded into strips, dried at room temperature and roasted for 1 hour at 500 ℃ to obtain the strip catalyst with the section diameter of 1.5 mm. And then excessively soaking the formed unmodified catalyst particles in a gallium nitrate aqueous solution with a certain concentration for 12 hours, determining the loading capacity of the gallium sesquioxide to be 2g according to the water absorption capacity and the solution concentration of the unmodified catalyst, drying the soaked sample at 120 ℃ for 6 hours, and roasting at 500 ℃ for 1 hour. Finally preparing the 10 wt% gallium trioxide modified nano-flake HZSM-11 molecular sieve catalyst.
2) 5g of the gallium sesquioxide modified nano-flake HZSM-11 molecular sieve catalyst is loaded into a miniature adiabatic fixed bed reactor with the inner diameter of 1.5cm, and zirconium oxide ceramic balls are respectively filled above and below a reaction bed layer; after the temperature is programmed to be raised to the reaction temperature of 420 ℃ for 90 minutes, reaction raw materials (the composition is shown in Table 1) are introduced, and the mass space velocity of the low-carbon hydrocarbon is kept at 4h-1The reaction pressure was 1.2 MPa. The low-carbon alkylation rate, the aromatic selectivity, the p-xylene selectivity and the p-xylene yield of the reaction are finally calculated by metering and gas chromatographic analysis of the catalytic reaction effluent liquid and the reaction tail gas, and the specific reaction results are shown in table 2.
Example 2
1) Weighing 19g of nano needle-shaped HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 500 and the needle-shaped crystal section diameter of 30nm, mixing with 1g of silicon oxide binder, rolling ball forming, airing at room temperature, and roasting at 500 ℃ for 1 hour to obtain spherical catalyst particles with the diameter of 1.5 mm. And then, respectively and excessively soaking the formed unmodified catalyst in a calcium nitrate aqueous solution, a lanthanum nitrate aqueous solution and an ammonium dihydrogen phosphate aqueous solution with certain concentrations for 12 hours in sequence, determining the loading amounts of calcium oxide, lanthanum oxide and phosphorus pentoxide to be 1.0g, 1.0g and 4.0g respectively according to the water absorption amount and the solution concentration of the unmodified catalyst, drying the soaked sample at 120 ℃ for 6 hours, and roasting at 500 ℃ for 1 hour. Finally, the nano needle-shaped HZSM-11 molecular sieve catalyst which is modified by compounding 5 wt% of calcium oxide, 5 wt% of lanthanum oxide and 20 wt% of phosphorus pentoxide is prepared.
2) 5g of the nano needle-shaped HZSM-11 modified by the calcium oxide, the lanthanum oxide and the phosphorus pentoxide in a composite wayThe sub-sieve catalyst is loaded into a micro moving bed reactor with the inner diameter of 1.5 cm; after the temperature is programmed to 700 ℃ after 120 minutes, the reaction raw material is introduced, and the mass space velocity of the low-carbon hydrocarbon is kept at 0.1h-1The reaction pressure was 0.1 MPa. The conversion rate of low-carbon hydrocarbon, the selectivity of aromatic hydrocarbon, the selectivity of p-xylene and the yield of p-xylene of the reaction are finally calculated by metering and gas chromatography analysis of the catalytic reaction effluent and the reaction tail gas, and the specific reaction results are shown in table 2.
Example 3
1) Weighing 8g of nano flaky HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 2 and the flaky crystal thickness of 350nm, mixing 8g of nano needle-shaped HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 40 and the needle-shaped crystal section diameter of 450nm, then adding 4g of silicon oxide binder, kneading, extruding into strips, drying at room temperature, and roasting at 500 ℃ for 1 hour to obtain strip catalyst particles with the section diameter of 1.5 mm. The molded unmodified catalyst particles obtained above were then excessively immersed in an aqueous solution of zinc nitrate of a certain concentration for 12 hours, the loading of zinc oxide was determined to be 0.04g by the water absorption of the unmodified catalyst and the solution concentration, and the immersed sample was dried at 120 ℃ for 6 hours and then calcined at 500 ℃ for 1 hour. Finally, 0.2 wt% of zinc oxide modified mixed molecular sieve (nano-flake HZSM-11 and nano-needle HZSM-11) catalyst is prepared.
2) 5g of the zinc oxide modified mixed molecular sieve catalyst is loaded into a miniature adiabatic fixed bed reactor with the inner diameter of 1.5cm, and zirconium oxide ceramic balls are respectively filled above and below a reaction bed layer; after the temperature is programmed to be increased to 300 ℃ after 90 minutes, the reaction raw materials are introduced, and the mass space velocity of the low-carbon hydrocarbon is kept at 20 hours-1The reaction pressure was 5 MPa. The conversion rate of low-carbon hydrocarbon, the selectivity of aromatic hydrocarbon, the selectivity of p-xylene and the yield of p-xylene of the reaction are finally calculated by metering and gas chromatography analysis of the catalytic reaction effluent and the reaction tail gas, and the specific reaction results are shown in table 2.
Example 4
1) Weighing 8g of nano flaky HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 150 and the flaky crystal thickness of 2nm, mixing 8g of nano needle-shaped HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 280 and the needle-shaped crystal section diameter of 2nm, then adding 4g of alumina binder, stirring and mixing uniformly, dropwise adding a proper amount of dilute nitric acid, kneading, extruding into strips, drying at room temperature, and roasting at 500 ℃ for 1 hour to obtain strip-shaped catalyst particles with the section diameter of 1.5 mm. And then, respectively and excessively soaking the formed unmodified catalyst particles in a nickel nitrate aqueous solution, a tetraethyl orthosilicate cyclohexane solution, a boric acid aqueous solution and a magnesium nitrate aqueous solution with certain concentrations for 12 hours in sequence, determining the loading amounts of nickel oxide, silicon dioxide, diboron trioxide and magnesium oxide to be 0.4g, 2.0g, 0.8g and 0.4g respectively according to the absorption amount and the solution concentration of the unmodified catalyst, drying the sample after each soaking at 120 ℃ for 6 hours, and roasting at 500 ℃ for 1 hour. Finally, the mixed molecular sieve (nano-flake HZSM-11 and nano-needle HZSM-11) catalyst modified by the combination of 2.0 wt% of nickel oxide, 10 wt% of silicon dioxide, 4 wt% of boron trioxide and 2.0 wt% of magnesium oxide is prepared.
2) 5g of the mixed molecular sieve catalyst compositely modified by the nickel oxide, the silicon dioxide, the boron trioxide and the magnesium oxide is filled into a miniature adiabatic fixed bed reactor with the inner diameter of 1.5cm, and zirconia ceramic balls are respectively filled above and below a reaction bed layer; after the temperature is programmed to 500 ℃ after 90 minutes, the reaction raw materials are introduced, and the mass space velocity of the low-carbon hydrocarbon is kept at 10h-1The reaction pressure was 3 MPa. The conversion rate of low-carbon hydrocarbon, the selectivity of aromatic hydrocarbon, the selectivity of p-xylene and the yield of p-xylene of the reaction are finally calculated by metering and gas chromatography analysis of the catalytic reaction effluent and the reaction tail gas, and the specific reaction results are shown in table 2.
Example 5
1) Weighing 9.5g of nano needle-shaped HZSM-11 molecular sieve with the silicon-aluminum atom molar ratio of 120 and the needle-shaped crystal section diameter of 10nm, mixing with 0.5g of silicon oxide binder and water to prepare slurry, performing spray drying to obtain microspherical catalyst particles with the outer diameter of 50-300 um, and then roasting at 500 ℃ for 1 hour. And then, the microsphere catalyst formed by spray drying is respectively and sequentially immersed in a copper nitrate aqueous solution, a silver nitrate aqueous solution, an ammonium molybdate aqueous solution and a polysiloxane solution with certain concentrations for 12 hours in an excessive way, the loading amounts of copper oxide, silver oxide, molybdenum oxide and silicon dioxide are respectively 0.2g, 0.1g, 0.5g and 1.1g determined by the liquid absorption amount and the solution concentration of the unmodified catalyst, and a sample after each immersion is dried at 120 ℃ for 6 hours and then calcined at 500 ℃ for 1 hour. Finally, the nano needle-shaped HZSM-11 molecular sieve catalyst modified by 2 wt% of copper oxide, 1 wt% of silver oxide, 5 wt% of molybdenum oxide and 11 wt% of silicon dioxide is prepared.
2) 5g of the copper oxide, silver oxide, molybdenum oxide and silicon dioxide composite modified nanometer acicular HZSM-11 molecular sieve catalyst is loaded into a micro fluidized bed reactor; after the temperature is programmed to 380 ℃ after 90 minutes, the reaction raw materials are introduced, and the mass airspeed of the low-carbon hydrocarbon is kept at 8 hours-1The reaction pressure was 0.8 MPa. The conversion rate of low-carbon hydrocarbon, the selectivity of aromatic hydrocarbon, the selectivity of p-xylene and the yield of p-xylene of the reaction are finally calculated by metering and gas chromatography analysis of the catalytic reaction effluent and the reaction tail gas, and the specific reaction results are shown in table 2.
Comparative examples
This embodiment is different from embodiment 4 in that: the conventional HZSM-5 molecular sieve with the silicon-aluminum atom molar ratio of 12.5 and the cubic grain size of 1.0um is used as the active component of the catalyst, and the composition, the component proportion, the preparation operation and the reaction evaluation conditions of the catalyst are the same as those of the example 4.
TABLE 1 Low carbon Hydrocarbon reaction feed composition
| Raw material components | Propane | Propylene (PA) | Butane | Butene (butylene) | Pentane (pentane) | Pentene and pentene composition | Hexane (C) | Hexene | Others |
| Content of Components (wt%) | 8.5 | 5.3 | 18.3 | 30.4 | 16.4 | 11.5 | 3.2 | 4.3 | 2.1 |
TABLE 2 catalytic reaction results of the examples
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions and substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (9)
1. The catalyst for efficiently synthesizing p-xylene through low-carbon hydrocarbon shape-selective aromatization is characterized by comprising a short-pore HZSM-11 molecular sieve with a special shape, a binder and a modification auxiliary agent; wherein the weight part ratio of the short-pore HZSM-11 molecular sieve with special morphology to the binder is 50-95 wt% and 5-50 wt%, respectively; the content of the modified auxiliary agent is 0.1-30 wt% of the total weight of the molecular sieve and the binder.
2. The catalyst according to claim 1, wherein the specially-shaped short-pore HZSM-11 molecule is selected from one or a mixture of a nano-flake HZSM-11 with a flake crystal thickness of 2-350 nm and a nano-needle HZSM-11 with a needle crystal section diameter of 2-450 nm.
3. The catalyst of claim 1, wherein the special morphology short pore HZSM-11 molecular sieve has a silicon to aluminum atom mole ratio of 2 to 500.
4. The catalyst of claim 1, wherein the binder is selected from alumina or silica.
5. The catalyst according to claim 1, wherein the modification promoter is selected from oxides of one or more elements selected from lanthanum, silicon, calcium, boron, phosphorus, magnesium, nickel, copper, zinc, gallium, molybdenum, and silver.
6. The catalyst of claim 1, wherein the catalyst is in the form of a rod or sphere.
7. The catalyst of claim 1, wherein the operating conditions of the catalyst applied to catalyze the shape-selective aromatization of lower hydrocarbons to paraxylene are as follows: the mass space velocity of the low-carbon hydrocarbon is 0.1-20 h-1The reaction pressure is 0.1-5 MPa, and the reaction temperature is 300-700 ℃.
8. The catalyst of claim 7, wherein the lower hydrocarbon is selected from the group consisting ofComprising C3～C6Alkanes and dilute hydrocarbons.
9. The catalyst of claim 1, wherein the low-carbon hydrocarbons comprise refinery gas, light gasoline, oil gas light hydrocarbons and light hydrocarbons byproduct from a coal chemical production process, and the aromatization catalytic reaction applied to the catalyst adopts a fixed bed reactor, a moving bed reactor or a fluidized bed reactor.
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| CN201911096983.2A CN110694675A (en) | 2019-11-11 | 2019-11-11 | Catalyst for efficiently synthesizing p-xylene by low-carbon hydrocarbon shape-selective aromatization |
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