A method for C4-C6 alkane conversion
The catalyst precursor prepared by spray drying and spheroidizing, combined with impregnation of precious metals and molecular sieves, solves the problem of low conversion rate of C4-C6 alkanes, and realizes efficient ethylene production and simple catalyst preparation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-26
- Publication Date
- 2026-05-26
AI Technical Summary
In existing technologies, the yields of C4-C6 alkanes converted into ethane, propane, and n-butane are low, resulting in low ethylene production efficiency. Furthermore, the catalyst preparation methods are complex and difficult to control.
Catalyst precursors were prepared by spray drying and spheroidizing. Highly efficient catalysts were then prepared by impregnation with noble metals and molecular sieves for the conversion of C4 to C6 alkanes. The reaction conditions were easily controlled, and the catalysts exhibited high catalytic activity and good stability.
It achieves efficient conversion of C4-C6 alkanes into high-quality cracking feedstock, improves ethylene production yield, and the catalyst is simple to prepare and easy to recycle, with mild reaction conditions.
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Abstract
Description
Technical Field
[0001] This application relates to a method for the conversion of C4 to C6 alkanes, belonging to the field of chemical engineering. Background Technology
[0002] Light olefins (including ethylene, propylene, and butene) are key basic chemical raw materials for the industrial production of plastics and other important chemicals. In commercial olefin production processes, olefin products are mainly obtained through the steam cracking of naphtha. Ethylene is the most in-demand basic chemical raw material, with 95% of the world's ethylene production using steam cracking. Domestic steam cracking capacity for ethylene production also exceeds 80% of the total ethylene production capacity. Steam cracking for ethylene production is a non-catalytic thermal process, and the ethylene yield is determined by the overall composition of the feedstock. The main feedstock for domestic steam cracking units is naphtha, but the ethylene yield from naphtha cracking is typically only around 30%, far lower than that of ethane (approximately 80%), propane (approximately 40%), and n-butane (approximately 40%). C4-C6 alkanes are important components of naphtha; converting them first to ethane, propane, and n-butane before feeding them into the steam cracking unit can significantly improve the ethylene yield.
[0003] Spherical catalysts have advantages such as good flowability, low wear, and convenient loading and unloading processes. Currently, the main methods for preparing spherical catalysts include: spray drying molding, spherical granulation, in-oil molding, and roll forming.
[0004] Rotational molding involves feeding powder, a suitable amount of water, or a binder into a slowly rotating container. The powder particles agglomerate under the action of capillaries and liquid bridges, forming micronuclei. Under the friction and rolling impact generated by the container's rotation, the powder layer continuously rotates and grows, eventually becoming spherical particles of a certain size and leaving the container. Rotational molding has a large processing capacity, requires less equipment investment, and has a high operating rate. Summary of the Invention
[0005] According to one aspect of this application, a method for the conversion of C4 to C6 alkanes is provided, characterized in that...
[0006] In a reactor, a raw material containing hydrogen and C4-C6 alkanes is contacted with a catalyst and reacted to obtain a product containing small molecule hydrocarbons.
[0007] The C4-C6 alkane is selected from at least one of n-butane, isobutane, n-pentane, isopentane, and 2,3-dimethylbutane;
[0008] The small molecule hydrocarbons are selected from at least one of ethane, propane, n-butane, and n-pentane;
[0009] The catalyst exhibits high catalytic performance, with high selectivity for high-quality pyrolysis feedstock in the product. At the same time, the catalyst has high stability, high catalytic activity, good selectivity, and is not easily deactivated.
[0010] The catalyst is prepared by the following steps:
[0011] (1) Clay and sol were mixed and spray-dried to obtain microspheres with a diameter of 1 to 50 μm;
[0012] (2) The microspheres were immersed in an aqueous solution containing a noble metal precursor, dried (I), calcined (I), and treated with a hydrogen atmosphere to obtain the catalyst precursor.
[0013] (3) The catalyst precursor, molecular sieve and additives are mixed, spheroidized, dried (II), calcined (II), and reduced to obtain the catalyst.
[0014] Optionally, the following steps are included:
[0015] (1) One or more of boehmite, kaolin, montmorillonite, activated clay, and attapulgite are mixed with silica sol, alumina sol, zircon sol, and titanium sol to form a slurry, and then microspheres are made by spray drying.
[0016] (2) The noble metal component precursor was loaded onto microspheres by impregnation, dried (I), calcined (I), and treated with H2 atmosphere at a certain temperature of 300-500℃ to obtain the catalyst precursor;
[0017] (3) The catalyst precursor, molecular sieve and additives are mixed evenly, and the mixture is spherically shaped, dried (II), calcined (II), and reduced to obtain the catalyst.
[0018] The clay is selected from at least one of boehmite, kaolin, montmorillonite, activated clay, and attapulgite.
[0019] The sol is selected from at least one of silica sol, aluminum sol, zirconium sol, and titanium sol;
[0020] The ratio of clay to solvent is 1 to 5:1.
[0021] The precious metal precursor is selected from soluble salts of platinum, palladium, and gold;
[0022] Specifically, the noble metal precursor is selected from at least one of chloroplatinic acid, tetraammineplatinum chloride, platinum nitrate, palladium nitrate, palladium chloride, ammonium chloropalladate, tetraammineplatinum chloride, gold chloride, and gold nitrate.
[0023] In the aqueous solution containing the noble metal precursor, the concentration of the noble metal precursor is 1-10 wt%.
[0024] The solid-liquid ratio of the microspheres to the aqueous solution containing the noble metal precursor is 0.1 to 0.5:1.
[0025] The temperature of the drying process I is 30–120°C;
[0026] The drying time for step I is 1–20 hours.
[0027] The temperature of the calcination I is 300–600°C;
[0028] The calcination time for step I is 1–10 hours.
[0029] The temperature for hydrogen atmosphere treatment is 300–500°C;
[0030] The hydrogen atmosphere treatment time is 1–10 hours.
[0031] The impregnation can be either equal-volume impregnation or excessive impregnation.
[0032] The molecular sieve is selected from at least one of ZSM-5 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, MOR molecular sieve, Y molecular sieve, and β molecular sieve.
[0033] The additive is selected from at least one of polyethylene glycol, polyvinyl alcohol, graphite, starch, sodium stearate, magnesium stearate, and guar gum.
[0034] The mass ratio of molecular sieve to additive in the catalyst precursor is 0.1 to 10:1.
[0035] During the ball rolling process, a molding auxiliary aqueous solution is sprayed. The solute in the molding auxiliary aqueous solution is at least one of trimethylhexadecylammonium chloride, hydrochloric acid, nitric acid, citric acid, tartaric acid, acetic acid, dodecyl phosphate, sodium dodecyl sulfonate and benzalkonium chloride palmitate, with a solute mass content of 0.5 to 2 wt%.
[0036] The temperature of the drying II process is 80–120°C;
[0037] The drying time for step II is 1–10 hours.
[0038] The temperature of calcination II is 300–600°C;
[0039] The roasting time for the second stage is 1 to 10 hours.
[0040] The reactor is a fixed-bed reactor, a fluidized-bed reactor, or a moving-bed reactor.
[0041] In the raw materials, the molar ratio of hydrogen to C4-C6 alkanes is 0.5-5:1;
[0042] The raw materials contain C4-C6 alkanes with a mass hourly space velocity (HHSV) of 0.1-10 h⁻¹. -1 ;
[0043] The reaction temperature is 200–500°C;
[0044] The reaction is carried out at a pressure of 0.1–3 MPa.
[0045] The beneficial effects that this application can produce include:
[0046] (1) The inventive point of this application is to provide a simple and efficient method for preparing a C4-C6 alkane conversion catalyst. The method involves the stepwise formation of an acidic component and a noble metal active component to obtain a low-carbon hydrocarbon conversion catalyst with high catalytic activity and strong stability. The preparation method is simple and the reaction conditions are easy to control.
[0047] (2) The method described in this application is simple and the reaction conditions are easy to control. It is a simple and efficient method for preparing a C4-C6 alkane conversion catalyst. Using this catalyst, isopentane conversion can be effectively catalyzed under mild conditions. The catalyst of this invention exhibits excellent reaction performance in the isopentane conversion reaction, including high isopentane conversion rate and high selectivity for high-quality steam cracking feedstocks (ethane, propane, n-butane, n-pentane), under mild reaction conditions. The operation is simple, and the catalyst is easy to prepare and recyclable. Detailed Implementation
[0048] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0049] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.
[0050] Example 1
[0051] (1) Weigh 30g of boehmite and mix it with an equal mass of silica sol to prepare a slurry. Then, spray dry the slurry to form microspheres of 10-50 micrometers.
[0052] (2) Chloroplatinic acid was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0053] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyethylene glycol, with a mass ratio of W:ZSM-5:polyethylene glycol = 1:1:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, 0.5 wt% citric acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110 °C overnight and then calcined at 550 °C for 3 h.
[0054] Example 2
[0055] (1) Weigh 30g of pseudoboehmite and mix it with an equal mass of zircon sol to prepare a mixed slurry. Then, by spray drying, the above slurry is made into microspheres of 10-50 micrometers;
[0056] (2) Tetraammineplatinum chloride was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0057] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyethylene glycol = 1:1:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, 0.5 wt% nitric acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110 °C overnight and then calcined at 550 °C for 3 h.
[0058] Example 3
[0059] (1) Weigh 30g of kaolin and mix it with an equal mass of zirconium sol to prepare a mixed slurry. Then, by spray drying, the above slurry is made into microspheres of 10-50 micrometers;
[0060] (2) Tetraammineplatinum chloride was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0061] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyvinyl alcohol = 1:1:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, a 0.5 wt% acetic acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110°C overnight and then calcined at 550°C for 3 hours.
[0062] Example 4
[0063] (1) Weigh 30g of kaolin and mix it with an equal mass of zirconium sol to prepare a mixed slurry. Then, by spray drying, the above slurry is made into microspheres of 10-50 micrometers;
[0064] (2) Tetraammineplatinum chloride was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0065] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyvinyl alcohol = 1:1:0.5. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, a 0.5 wt% acetic acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110°C overnight and then calcined at 550°C for 3 hours.
[0066] Example 5
[0067] (1) Weigh 30g of montmorillonite and mix it with an equal mass of titanium sol to prepare a slurry. Then, spray dry the slurry to form microspheres of 10-50 micrometers.
[0068] (2) Platinum nitrate was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0069] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyvinyl alcohol = 1:2:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, 0.5 wt% tartaric acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110°C overnight and then calcined at 550°C for 3 hours.
[0070] Example 6
[0071] (1) Weigh 30g of montmorillonite and mix it with an equal mass of titanium sol to prepare a slurry. Then, spray dry the slurry to form microspheres of 10-50 micrometers.
[0072] (2) Platinum nitrate was dissolved in water to prepare a precursor solution. Platinum was loaded onto the material obtained in (1) by excess impregnation, with a platinum loading of 2%. The obtained material was dried at 100°C for 5 hours and then calcined in air at 500°C for 2 hours. After calcination, the obtained material was treated in hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0073] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyvinyl alcohol = 1:2:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, 0.5 wt% tartaric acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110°C overnight and then calcined at 550°C for 3 hours.
[0074] Example 7
[0075] (1) Weigh 30g of activated clay and mix it with an equal mass of aluminum sol to prepare a mixed slurry. Then, spray dry the slurry to form microspheres of 10-50 micrometers.
[0076] (2) Palladium chloride was dissolved in water to prepare a precursor solution. Palladium was loaded onto the material obtained in (1) by excess impregnation, with a palladium loading of 2%. The obtained material was dried at 100°C for 5 hours, and then calcined at 500°C in air for 2 hours. After calcination, the obtained material was treated in a hydrogen atmosphere at 460°C for 2 hours to obtain material W;
[0077] (3) The material W obtained in (2) is mixed with a certain mass of ZSM-5 molecular sieve and polyvinyl alcohol, with a mass ratio of W:ZSM-5:polyvinyl alcohol = 1:2:1. The mixture is then formed into spherical materials with a diameter of 1.5 mm to 2.0 mm by ball rolling. During the ball rolling process, a 0.5 wt% citric acid aqueous solution is sprayed to assist in the forming. The resulting material is dried at 110°C overnight and then calcined at 550°C for 3 hours.
[0078] Example 8 Comparative Example 1
[0079] 30g of boehmite and an equal mass of water were weighed and mixed, and the resulting slurry was spray-dried to obtain microspheres. The microspheres were then mixed with an excess of chloroplatinic acid aqueous solution, with a platinum loading of 2%. The mixture was dried at 110℃ for 12 hours and calcined in air at 500℃ for 2 hours. Subsequently, the above material was mixed with ZSM-5 molecular sieve and water in a ratio of 1:1:0.5, and the mixture was ball-forming into spherical materials with a diameter of 1.5mm to 2.0mm. A 0.1wt% citric acid aqueous solution was sprayed during the ball-forming process. The resulting material was dried at 110℃ overnight and calcined at 550℃ for 3 hours.
[0080] Example 9 Comparative Example 2
[0081] 30g of pseudokaolin and an equal mass of water were mixed, and the resulting slurry was spray-dried to obtain microspheres. The microspheres were then mixed with an excess of a platinum tetraamminenitrate aqueous solution, with a platinum loading of 2%. The mixture was dried at 110℃ for 12 hours and calcined at 500℃ in air for 2 hours. Subsequently, the above material was mixed with ZSM-5 molecular sieve and water in a ratio of 1:1:0.5, and the mixture was ball-forming into spherical materials with a diameter of 1.5mm–2.0mm. A 0.1wt% acetic acid aqueous solution was sprayed during the ball-forming process. The resulting material was dried at 110℃ overnight and calcined at 550℃ for 3 hours.
[0082] Example 10 Evaluation of the catalyst's isopentane conversion activity
[0083] The C4-C6 alkane used in the catalyst evaluation was isopentane. The isopentane conversion catalytic performance of catalysts 1#-7# prepared in Examples 1-7 and the comparative catalyst was evaluated using a fixed-bed reactor with an inner diameter of 9 mm and a catalyst loading of 2 mL. After reduction with hydrogen, the catalyst was reacted with a feedstock containing isopentane and hydrogen. The products were analyzed online using an Agilent 7890A chromatograph. The catalyst activity was evaluated based on indicators such as isopentane conversion and selectivity for high-quality cracked feedstock. The calculation methods for each indicator are as follows:
[0084]
[0085] isopentane 进The mass flow rate (kg / h) of isopentane at the reactor inlet; isopentane 出 and (ethane + propane + n-butane) 出 The values represent the mass flow rates (kg / h) of isopentane and high-quality pyrolysis feedstock at the reactor outlet, respectively. Table 1 shows the catalysts and catalyst pretreatment conditions, reaction conditions, and isopentane reactivity of the catalysts in Examples 1–9.
[0086] Table 1. Pretreatment conditions, reaction conditions, and catalyst activity of Examples 1-8
[0087]
[0088]
[0089] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for converting C4-C6 alkanes, characterized in that, In a reactor, a raw material containing hydrogen and C4-C6 alkanes is contacted with a catalyst and reacted to obtain a product containing small molecule hydrocarbons. The C4-C6 alkane is selected from at least one of n-butane, isobutane, n-pentane, isopentane, and 2,3-dimethylbutane; The small molecule hydrocarbons are selected from at least one of ethane, propane, n-butane, and n-pentane; The catalyst is prepared by the following steps: (1) Clay and sol were mixed and spray-dried to obtain microspheres with a diameter of 1 to 50 μm; (2) The microspheres were immersed in an aqueous solution containing a noble metal precursor, dried (I), calcined (I), and treated with a hydrogen atmosphere to obtain the catalyst precursor. (3) The catalyst precursor, molecular sieve and additives are mixed, spheroidized, dried (II), calcined (II), and reduced to obtain the catalyst.
2. The method according to claim 1, characterized in that, The clay is selected from at least one of boehmite, kaolin, montmorillonite, activated clay, and attapulgite. The sol is selected from at least one of silica sol, aluminum sol, zirconium sol, and titanium sol; The ratio of clay to sol is 1 to 5:
1.
3. The method according to claim 1, characterized in that, The precious metal precursor is selected from soluble salts of platinum, palladium, and gold; In the aqueous solution containing the noble metal precursor, the concentration of the noble metal precursor is 1-10 wt%.
4. The method according to claim 1, characterized in that, The solid-liquid ratio of the microspheres to the aqueous solution containing the noble metal precursor is 0.1 to 0.5:
1.
5. The method according to claim 1, characterized in that, The temperature of the drying process I is 30–120°C; The drying time for step I is 1–20 hours; The temperature of the calcination I is 300–600°C; The roasting time for step I is 1 to 10 hours; The temperature for hydrogen atmosphere treatment is 300–500°C; The hydrogen atmosphere treatment time is 1 to 10 hours; The impregnation can be either equal-volume impregnation or excessive impregnation.
6. The method according to claim 1, characterized in that, The molecular sieve is selected from at least one of ZSM-5 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, MOR molecular sieve, Y molecular sieve, and β molecular sieve. The additive is selected from at least one of polyethylene glycol, polyvinyl alcohol, graphite, starch, sodium stearate, magnesium stearate, and guar gum.
7. The method according to claim 1, characterized in that, The mass ratio of molecular sieve to additive in the catalyst precursor is 0.1 to 10:
1.
8. The method according to claim 1, characterized in that, The temperature of the drying II process is 80–120°C; The drying time for step II is 1–10 hours; The temperature of calcination II is 300–600°C; The roasting time for the second stage is 1 to 10 hours.
9. The method according to claim 1, characterized in that, The reactor is a fixed-bed reactor, a fluidized-bed reactor, or a moving-bed reactor.
10. The method according to claim 1, characterized in that, In the raw materials, the molar ratio of hydrogen to C4-C6 alkanes is 0.5-5:1; The raw materials contain C4-C6 alkanes with a mass hourly space velocity (HHSV) of 0.1-10 h⁻¹. -1 ; The reaction temperature is 200–500°C; The reaction is carried out at a pressure of 0.1–3 MPa.