Method for deeply removing trace moisture in isopentane oil by using composite molecular sieve

Abstract

The invention discloses a method for deeply removing trace moisture in isopentane oil by using a composite molecular sieve, which comprises the following steps: under the conditions of temperature and pressure, enabling an isopentane oil raw material to flow through the composite molecular sieve to remove trace moisture in isopentane; the composite molecular sieve is formed by compounding and molding an ordered mesoporous molecular sieve and an A-type molecular sieve in a mass ratio of 1: (0.5-5). The isopentane oil is refined under the non-hydrogenation condition by adopting a multi-stage composite pore channel molecular sieve combination method, and the method has the advantages of simple process, low cost and convenience in operation, and can be used for industrial production of the isopentane foaming agent.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical industry, and in particular to a method for deeply removing trace water in isopentane oil by using a composite molecular sieve. Background Art

[0002] Isopentane is mainly used as a solvent for the production of linear low-density polyethylene and full-density polyethylene, a blowing agent for expandable polystyrene and polyurethane foam, etc. With the continuous advancement of polyethylene production technology, the requirements for the solvent isopentane are becoming higher and higher. The trace moisture requirements in isopentane oil usually depend on the specific application in which it is used. For example, in analytical chemistry, especially when using gas chromatography (GC), moisture in the solvent may affect the results of chromatographic analysis, so isopentane is usually required to be anhydrous or have a very low water content. In industrial production applications, such as solvents for synthetic polyethylene reactions, the presence of moisture may affect the activity of the catalyst or cause undesirable side reactions, so it is usually necessary to control the moisture content at a very low level.

[0003] Removing trace water from isopentane can improve the purity of isopentane, so that the purified isopentane can be used as a raw material for the processing of chemical products. In the prior art, trace water in isopentane oil is generally removed by a single type of molecular sieve, but when a single type of molecular sieve or dehydrating agent is used to remove water, there are problems such as low removal efficiency, low reuse rate and poor diffusion performance. Summary of the invention

[0004] The present invention aims to overcome the above-mentioned problems existing in the prior art when a single type of molecular sieve is used to remove water from isopentane oil, and provides a method for deeply removing trace water from isopentane oil by using a composite molecular sieve. The method adopts a multi-stage composite pore molecular sieve combination method to refine isopentane oil under non-hydrogenation conditions, and has the advantages of simple process, low cost and convenient operation, and can be used for the industrial production of isopentane foaming agent.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: under temperature and pressure conditions, allowing the isopentane oil raw material to flow through the composite molecular sieve to remove trace water from the isopentane; The composite molecular sieve is formed by compositely molding an ordered mesoporous molecular sieve and an A-type molecular sieve in a mass ratio of 1:0.5-5.

[0006] The present invention combines type A molecular sieve and ordered mesoporous molecular sieve to form a new composite molecular sieve for removing trace water in isopentane oil. The isopentane oil will diffuse rapidly on the ordered mesoporous molecular sieve first. The regular pore structure of the ordered mesoporous molecular sieve is more conducive to the rapid mass transfer of isopentane oil within the mesopore size range, reducing the diffusion resistance. Then the trace water entering the pores of the composite molecular sieve is adsorbed in the pores of the type A molecular sieve, and the isopentane oil with a larger diameter than the water molecule is separated from the molecular sieve pores, thereby purifying the isopentane oil. The ordered mesoporous molecular sieve and the type A molecular sieve cooperate with each other and selectively perform their respective functions, ultimately making the entire adsorption unit have very good water adsorption performance and stability. The present invention uses non-hydrogenation refining technology to process isopentane oil, so that it has the advantages of simple process, low cost and convenient operation, and can be used for the industrial production of isopentane foaming agent.

[0007] Preferably, the composite molding method of the composite molecular sieve is: mix the dried ordered mesoporous molecular sieve and type A molecular sieve for 15 to 30 minutes; add sesbania powder and water and continue mixing for 15 to 30 minutes; then add nitric acid solution and continue kneading for 20 to 40 minutes to obtain a mixture; extrude the mixture into strips, dry and roast to obtain the composite molecular sieve.

[0008] Preferably, the mass of the added sesbania powder is 0.5-2% of the mixture; the mass concentration of the added nitric acid solution is 5-30%, and the mass of the added nitric acid solution is 1-5% of the mixture.

[0009] Preferably, the composite molecular sieve after extrusion has a diameter of 1 to 3 mm and a length of 3 to 15 mm.

[0010] Preferably, the drying temperature is 110-130° C., and the drying time is 12-24 hours; the roasting temperature is 500-550° C., and the roasting time is 2-4 hours.

[0011] Preferably, the ordered mesoporous molecular sieve is one or two of SBA-15, MCM-41, and MCM-48; the pore size range of the ordered mesoporous molecular sieve is 2 to 8 nm.

[0012] Preferably, the type A molecular sieve is one or more of 3A, 4A and 5A molecular sieves.

[0013] Preferably, both ends of the composite molecular sieve are provided with inert fillers, and the inert fillers are inert glass beads and / or ceramic rings.

[0014] Preferably, before the isopentane oil feedstock flows through the composite molecular sieve, an inert gas is first passed through the composite molecular sieve to purge the composite molecular sieve.

[0015] Preferably, the inert gas is one of nitrogen, helium and argon, the purge temperature is 150-450° C., the purge flow rate of the inert gas is 80-200 mL / min, and the purge time is 0.5-5 h.

[0016] Preferably, the isopentane oil is isopentane or pentane isomer product obtained by distillation of a heavy naphtha reforming and hydrogenation unit.

[0017] Therefore, the present invention has the following beneficial effects: (1) The present invention uses a composite solid adsorbent composed of two molecular sieves, which can deeply remove trace amounts of water from isopentane oil and improve the quality of isopentane oil; the composite adsorbent has good adsorption performance and low isopentane loss; (2) Compared with traditional clay or existing molecular sieves, the composite molecular sieve loading used in the present invention can greatly increase the overall life of the molecular sieve for deep dehydration, without the need for frequent replacement; (3) The adsorbents used in the present invention, the ordered mesoporous molecular sieve and the type A molecular sieve, are both renewable, effectively avoiding the generation of solid waste and having little impact on the environment. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with specific implementation methods.

[0019] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0020] In each embodiment, the removal of trace water from isopentane oil is carried out in a fixed bed reactor, the inner diameter of the reaction tube is 1.5 cm, and the length is 75 cm. The water content of the reaction raw material isopentane oil is about 40-80 ppm.

[0021] Overall embodiment: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: under temperature and pressure conditions, allowing the isopentane oil raw material to flow through the composite molecular sieve to remove trace water from the isopentane; The composite molecular sieve is formed by compositely molding an ordered mesoporous molecular sieve and an A-type molecular sieve in a mass ratio of 1:0.5-5.

[0022] As a specific embodiment, the composite molding method of the composite molecular sieve is: mix the dried ordered mesoporous molecular sieve and type A molecular sieve for 15 to 30 minutes; add sesbania powder and water and continue mixing for 15 to 30 minutes; then add nitric acid solution and continue kneading for 20 to 40 minutes to obtain a mixture; extrude the mixture into strips, dry and roast to obtain the composite molecular sieve.

[0023] As a specific implementation, the mass of the added sesbania powder is 0.5-2% of the mixture; the mass concentration of the added nitric acid solution is 5-30%, and the mass of the added nitric acid solution is 1-5% of the mixture.

[0024] As a specific implementation, the diameter of the composite molecular sieve after extrusion is 1 to 3 mm, and the length is 3 to 15 mm.

[0025] As a specific implementation manner, the drying temperature is 110-130° C., and the drying time is 12-24 hours; the roasting temperature is 500-550° C., and the roasting time is 2-4 hours.

[0026] As a specific implementation, the ordered mesoporous molecular sieve is one or two of SBA-15, MCM-41, and MCM-48; the pore size range of the ordered mesoporous molecular sieve is 2 to 8 nm.

[0027] As a specific implementation, the type A molecular sieve is one or more of 3A, 4A and 5A molecular sieves.

[0028] As a specific implementation, both ends of the composite molecular sieve are provided with inert fillers, and the inert fillers are inert glass beads and / or ceramic rings.

[0029] As a specific implementation method, before the isopentane oil feedstock flows through the composite molecular sieve, an inert gas is first passed through the composite molecular sieve to purge it.

[0030] As a specific implementation, the inert gas is one of nitrogen, helium, and argon, the purge temperature is 150-450° C., the purge flow rate of the inert gas is 80-200 mL / min, and the purge time is 0.5-5 h.

[0031] As a specific implementation, the isopentane oil is the isopentane or pentane isomer product obtained after distillation of a heavy naphtha reforming and hydrogenation unit.

[0032] Embodiment 1: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-41 molecular sieve (pore size range of 2 to 8 nm) and 3A molecular sieve are mixed at a mass ratio of 1:5 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a composite molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 12 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0033] Embodiment 2: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-41 molecular sieve (pore size range of 2 to 8 nm) and 4A molecular sieve are mixed at a mass ratio of 1:2 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 110° C. for 24 hours and then calcined at 550° C. for 2 hours to obtain a composite molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 15 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0034] Embodiment 3: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-41 molecular sieve (pore size range of 2 to 8 nm) and 5A molecular sieve are mixed at a mass ratio of 1:1 for 20 minutes; after adding sesbania powder and water, the mixture is continued to be mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 130° C. for 12 hours, and then calcined at 500° C. for 4 hours to obtain a composite molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 20 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0035] Embodiment 4: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-41 molecular sieve (pore size range of 2 to 8 nm) and 3A molecular sieve are mixed at a mass ratio of 2:1 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a composite molecular sieve; (2) Inert glass beads were filled at the bottom of the reaction tube, and then 30 g of composite molecular sieve was weighed and loaded into the reaction tube, and then inert glass beads were filled to a height of 4 cm; after nitrogen was purged at 350 ° C for 3 h, the temperature was lowered to 160 ° C, and the atmosphere was switched to H2 to control the system pressure of the reaction system, and then the reaction pressure was controlled to 1.5 MPa, and then the mass space velocity was 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0036] Embodiment 5: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-48 molecular sieve (pore size range of 2 to 5 nm) and 5A molecular sieve are mixed at a mass ratio of 1:5 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 0.5% of the mixture, and the mass of the nitric acid solution added is 5% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a composite molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 20 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0037] Embodiment 6: A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available SBA-15 molecular sieve (pore size range of 2 to 6 nm) and 3A molecular sieve are mixed at a mass ratio of 1:5 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 2% of the mixture, and the mass of the nitric acid solution added is 1% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped composite molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a composite molecular sieve; (2) Inert glass beads were filled at the bottom of the reaction tube, and then 30 g of composite molecular sieve was weighed and loaded into the reaction tube, and then inert glass beads were filled to a height of 4 cm; after nitrogen was purged at 350 ° C for 3 h, the temperature was lowered to 160 ° C, and the atmosphere was switched to H2 to control the system pressure of the reaction system, and then the reaction pressure was controlled to 1.5 MPa, and then the mass space velocity was 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0038] Comparative Example 1 (filled with MCM-41 molecular sieve only): A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying commercially available MCM-41 molecular sieve (pore size range of 2-8 nm), sesbania powder and water are added and mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours and then calcined at 520° C. for 3 hours to obtain a molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 10 g of molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0039] Comparative Example 2 (filled with type A molecular sieve only): A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying commercially available 3A molecular sieve, add sesbania powder and water and mix for 20 minutes; then add nitric acid solution with a mass concentration of 20% and continue kneading for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped molecular sieve with a diameter of 1.5 mm and a length of 10 mm, dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 10 g of molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0040] Comparative Example 3 (using alumina molecular sieve instead of type A molecular sieve): A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available MCM-41 molecular sieve (pore size range of 2 to 8 nm) and alumina molecular sieve are mixed at a mass ratio of 1:5 for 20 minutes; after adding sesbania powder and water, the mixture is mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 12 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0041] Comparative Example 4 (using alumina molecular sieve instead of MCM-41 molecular sieve): A method for deeply removing trace water from isopentane oil by using a composite molecular sieve comprises the following steps: (1) After drying, commercially available alumina molecular sieve and 3A molecular sieve are mixed at a mass ratio of 1:5 for 20 minutes; after adding sesbania powder and water, the mixture is continued to be mixed for 20 minutes; then a nitric acid solution with a mass concentration of 20% is added and kneaded for 30 minutes to obtain a mixture; the mass of the sesbania powder added is 1% of the mixture, and the mass of the nitric acid solution added is 3% of the mixture; the mixture is extruded on an extruder to obtain a strip-shaped molecular sieve with a diameter of 1.5 mm and a length of 10 mm, which is dried at 120° C. for 12 hours, and then calcined at 520° C. for 3 hours to obtain a molecular sieve; (2) Fill the bottom of the reaction tube with inert glass beads, then weigh 12 g of composite molecular sieve, load it into the reaction tube, and then fill it with inert glass beads to a height of 4 cm; after nitrogen purging at 350°C for 3 h, cool to 160°C, switch the atmosphere to H2 to control the system pressure of the reaction system, and then control the reaction pressure to 1.5 MPa, and then at a mass space velocity of 1.0 h -1 The isopentane oil raw material was introduced into the reaction tube at an air velocity of , and the product at the outlet of the reaction tube was taken and its moisture content was analyzed using a Karl Fischer moisture tester. The test results are listed in Table 1.

[0042] Table 1: Water removal results from isopentane oil.

[0043] As can be seen from Table 1, in Examples 1 to 6, the composite molecular sieve was used to remove trace moisture in the isopentane oil, and the moisture content was maintained below 5 ppm after 90 days of continuous reaction.

[0044] In Comparative Example 1, only ordered mesoporous molecular sieve MCM-41 was used to remove moisture. Due to the low water adsorption capacity of MCM-41 molecular sieve, trace moisture in the isopentane oil could not be deeply removed. After 30 and 90 days of continuous reaction, the moisture content in the product was significantly improved compared with that in Example 1.

[0045] In Comparative Example 2, only type A molecular sieve was used to remove moisture. Since the isopentane molecules competed with the water molecules for diffusion inside the type A molecular sieve, some water molecules could not be adsorbed by the type A molecular sieve. After 90 days of continuous reaction, the moisture content in the product was significantly increased compared with that in Example 1.

[0046] In Comparative Example 3, a composite molecular sieve of MCM-41 molecular sieve and alumina molecular sieve was used to remove moisture. However, since their pore structure was not highly compatible with water molecules, the water removal effect was poor. After 90 days of continuous reaction, the moisture content in the product was significantly improved compared with that in Example 1.

[0047] In Comparative Example 4, a composite molecular sieve of alumina molecular sieve and type A molecular sieve was used to remove moisture. Since the diffusion of isopentane molecules in alumina and type A composite molecular sieve was hindered, the effect of adsorbing trace moisture was affected. After 90 days of continuous reaction, the moisture content in the product was also significantly improved compared with that in Example 1.

[0048] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for deeply removing trace water from isopentane oil using a composite molecular sieve, characterized in that: The method comprises the following steps: under temperature and pressure conditions, allowing the isopentane oil raw material to flow through a composite molecular sieve to remove trace water in the isopentane; The composite molecular sieve is formed by compositely molding an ordered mesoporous molecular sieve and an A-type molecular sieve in a mass ratio of 1:0.5-5.

2. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 1, characterized in that: The composite molding method of the composite molecular sieve is as follows: mixing the dried ordered mesoporous molecular sieve and type A molecular sieve for 15 to 30 minutes; adding sesbania powder and water and continuing to mix for 15 to 30 minutes; then adding nitric acid solution and continuing to knead for 20 to 40 minutes to obtain a mixture; extruding the mixture into strips, drying and roasting to obtain the composite molecular sieve.

3. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 2, characterized in that: The mass of the added sesbania powder is 0.5-2% of the mixture; the mass concentration of the added nitric acid solution is 5-30%, and the mass of the added nitric acid solution is 1-5% of the mixture.

4. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 2, characterized in that: The diameter of the composite molecular sieve after extrusion is 1~3mm and the length is 3~15mm.

5. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 2, characterized in that: The drying temperature is 110~130℃, and the drying time is 12~24h; the roasting temperature is 500~550℃, and the roasting time is 2~4h.

6. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 1 or 2, characterized in that: The ordered mesoporous molecular sieve is one or two of SBA-15, MCM-41 and MCM-48; the pore size range of the ordered mesoporous molecular sieve is 2-8 nm.

7. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 1 or 2, characterized in that: The type A molecular sieve is one or more of 3A, 4A and 5A molecular sieves.

8. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 1, characterized in that: Both ends of the composite molecular sieve are provided with inert fillers, which are inert glass beads and / or ceramic rings.

9. The method for removing trace water from isopentane oil by composite molecular sieve depth according to claim 1, characterized in that Before the pentane oil feedstock flows through the composite molecular sieve, the composite molecular sieve is first purged with an inert gas.

10. The method for deeply removing trace water from isopentane oil by using a composite molecular sieve according to claim 1, characterized in that: The isopentane oil is the isopentane or pentane isomer product obtained after distillation of a heavy naphtha reforming and hydrogenation unit.

Images