CN117942932A - 5A molecular sieve adsorbent and preparation method and application thereof - Google Patents
5A molecular sieve adsorbent and preparation method and application thereof Download PDFInfo
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 138
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 138
- 239000003463 adsorbent Substances 0.000 title claims abstract description 77
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000008188 pellet Substances 0.000 claims abstract description 86
- 239000011230 binding agent Substances 0.000 claims abstract description 48
- 238000000034 method Methods 0.000 claims abstract description 45
- 239000002131 composite material Substances 0.000 claims abstract description 39
- 238000001179 sorption measurement Methods 0.000 claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000011159 matrix material Substances 0.000 claims abstract description 26
- 239000000843 powder Substances 0.000 claims abstract description 26
- 238000001035 drying Methods 0.000 claims abstract description 16
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical group [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 13
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 13
- 239000011575 calcium Substances 0.000 claims abstract description 13
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 13
- 239000011734 sodium Substances 0.000 claims abstract description 13
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 13
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000004115 Sodium Silicate Substances 0.000 claims abstract description 10
- 229910052911 sodium silicate Inorganic materials 0.000 claims abstract description 10
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 238000000926 separation method Methods 0.000 claims abstract description 8
- 238000005406 washing Methods 0.000 claims abstract description 8
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 7
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 4
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 42
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 21
- 238000001354 calcination Methods 0.000 claims description 15
- 239000003795 chemical substances by application Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000009736 wetting Methods 0.000 claims description 6
- 239000013078 crystal Substances 0.000 claims description 5
- 230000000274 adsorptive effect Effects 0.000 claims description 3
- 239000012535 impurity Substances 0.000 abstract description 6
- 239000000126 substance Substances 0.000 abstract description 3
- 238000003912 environmental pollution Methods 0.000 abstract description 2
- 238000005096 rolling process Methods 0.000 description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 8
- 239000000463 material Substances 0.000 description 7
- 150000001335 aliphatic alkanes Chemical class 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000012752 auxiliary agent Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 2
- 239000005751 Copper oxide Substances 0.000 description 2
- 241000219782 Sesbania Species 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 150000003863 ammonium salts Chemical class 0.000 description 2
- 229910001424 calcium ion Inorganic materials 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 229910000431 copper oxide Inorganic materials 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 229910000480 nickel oxide Inorganic materials 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 2
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 2
- 239000003209 petroleum derivative Substances 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000009495 sugar coating Methods 0.000 description 2
- 239000005995 Aluminium silicate Substances 0.000 description 1
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical group O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Abstract
The invention relates to the technical field of chemical adsorption separation, and discloses a 5A molecular sieve adsorbent, a preparation method and application thereof. The preparation method comprises the following steps: (1) Performing ball forming on powder containing a 4A molecular sieve and a composite binder to obtain balls, and drying and roasting the balls to obtain matrix balls; (2) Prewetting the matrix pellets, and then performing calcium exchange to obtain 5A molecular sieve pellets; (3) Washing the 5A molecular sieve pellets with water, drying, and roasting to obtain a 5A molecular sieve adsorbent; wherein the composite binder is a mixture of sodium metaaluminate and sodium silicate and/or silicic acid, and the molar ratio of silicon to aluminum is 1.5-2.5. The binder prepared by the method has the advantages of low impurity content, small environmental pollution, large adsorption capacity, high strength and the like.
Description
Technical Field
The invention relates to the technical field of chemical adsorption separation, in particular to a 5A molecular sieve adsorbent, and a preparation method and application thereof.
Background
N-alkanes are important base chemicals for the production of detergents, chlorinated paraffins, plasticizers, and the like. The molecular diameter of normal alkane in petroleum products is smaller than 0.5nm, the molecular diameter of other isoparaffin, naphthene, arene and the like is larger than 0.5nm, the effective aperture of the 5A molecular sieve is 0.5nm, and the normal alkane can be adsorbed, while other hydrocarbons are prevented from entering the pore canal of the molecular sieve, and according to the adsorption characteristic, the normal alkane can be separated and adsorbed from the petroleum products by using the 5A molecular sieve as an adsorbent.
CN87105499a discloses a method for preparing a binder-free spherical a-type molecular sieve, which uses inorganic ammonium salt, inorganic acid and water glass as raw materials, uses an oil column forming method to prepare silica hydrogel pellets, carries out water washing, surfactant soaking, drying and roasting to prepare low-bulk silica pellets, mixes the silica pellets with sodium metaaluminate solution, carries out aging and crystallization at a certain temperature, enables the silica to be basically converted into a 4A molecular sieve, and then carries out calcium exchange to obtain a 5A molecular sieve. The process brings two major pollutions in the production process, ammonia nitrogen sewage which is difficult to treat is produced by using inorganic ammonium salt, COD of the sewage exceeds standard by using a surfactant, and thus the pollution treatment difficulty is high.
CN201310516673.8 discloses a 5A molecular sieve adsorbent, its preparation method and application, the method comprises: performing ball rolling molding on powder containing the 4A molecular sieve and the binder to obtain balls; and drying and roasting the pellets to obtain matrix pellets. The binder is kaolin, diatomite and the like, and the binder contains impurities such as ferric oxide, nickel oxide, copper oxide and the like, particularly has higher ferric oxide content, has certain catalytic activity, can cause a small amount of alkane to carry out cracking reaction or cause trace olefin in oil products to carry out superposition reaction during the adsorption and separation operation process, and has the risk of blocking part of molecular sieve pore channels and influencing the service life of the adsorbent.
Considering that the service period of the common adsorbent is more than 5 years, in order to ensure the long-period and high-efficiency operation of the adsorption separation device, a new binder with less impurities is necessary to be adopted, and the adsorbent with high strength, high adsorption capacity and long service life is obtained through optimization of the adsorbent forming method and the preparation process.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a preparation method of the 5A molecular sieve adsorbent, which has the advantages of low content of binder impurities, small environmental pollution, large adsorption capacity, high strength and the like.
In order to achieve the above object, an aspect of the present invention provides a method for preparing a 5A molecular sieve adsorbent, the method comprising:
(1) Performing ball forming on powder containing a 4A molecular sieve and a composite binder to obtain balls, and drying and roasting the balls to obtain matrix balls;
(2) Prewetting the matrix pellets, and then performing calcium exchange to obtain 5A molecular sieve pellets;
(3) Washing the 5A molecular sieve pellets with water, drying, and roasting to obtain a 5A molecular sieve adsorbent;
Wherein the composite binder is a mixture of sodium metaaluminate and sodium silicate and/or silicic acid, and the molar ratio of silicon to aluminum is 1.5-2.5.
Preferably, in the step (1), the silicon-aluminum molar ratio of the composite binder is 1.7-2.3.
Preferably, in step (1), the average crystallite diameter of the 4A molecular sieve is from 0.01 to 2.0. Mu.m, preferably from 0.5 to 0.9. Mu.m.
Preferably, in step (1), the methanol adsorption capacity of the 4A molecular sieve is 160-190mg/g, more preferably 180-190mg/g.
Preferably, in the step (1), the content of the 4A molecular sieve in the powder is 90-99.9 wt%, the content of the composite binder is 0.1-10 wt%, the content of the pore-forming agent is 0-7 wt%, more preferably, the content of the 4A molecular sieve in the powder is 90-99 wt%, the content of the composite binder is 0.1-9 wt%, and the content of the pore-forming agent is 0.1-7 wt%.
Preferably, in step (2), the pre-wetting is such that the water content of the pre-wetted matrix pellets is above 17 wt%, preferably 19-23 wt%.
Preferably, in step (3), the calcining comprises vacuum calcining the 5A molecular sieve pellets under vacuum- (10-100) kPa.
Preferably, in step (3), the calcination conditions are such that the water content of the calcined 5A molecular sieve pellets is less than 3.5 wt.%.
Preferably, in step (3), the roasting conditions include: the roasting temperature is 200-900 ℃, preferably 350-550 ℃; the vacuum degree of roasting is- (10-100) kPa, preferably- (80-95) kPa; the calcination time is 1 to 5 hours, preferably 2 to 3 hours.
In a second aspect, the present invention provides a 5A molecular sieve adsorbent prepared by the method of the first aspect described above.
Preferably, the 5A molecular sieve adsorbent has an n-hexane adsorption amount of 125mg/g or more, preferably 135mg/g or more.
In a third aspect the present invention provides the use of the 5A molecular sieve adsorbent of the second aspect described above in the adsorptive separation of normal paraffins, preferably normal hexane.
According to the technical scheme, the powder containing the 4A molecular sieve and the composite binder is subjected to ball forming, then is dried and roasted to obtain the matrix pellets, and then the matrix pellets are subjected to calcium exchange, drying and roasting after being pre-wetted, so that the 5A molecular sieve adsorbent prepared by the method has the advantages of large adsorption quantity of normal paraffins (such as normal hexane), high adsorption efficiency, good strength and the like. And furthermore, the method disclosed by the invention is simple in technological process, does not need to use a surfactant in the preparation process and has no emission of ammonia nitrogen wastewater, so that clean production is effectively realized. Therefore, the method is environment-friendly and is very suitable for industrial application.
The binder adopted by the invention has low impurity content, and is favorable for prolonging the service life of the adsorbent. In addition, the invention adopts the vacuum roasting activation mode, thereby further improving the adsorption capacity of the product.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a preparation method of a 5A molecular sieve adsorbent, which comprises the following steps:
(1) Performing ball forming on powder containing a 4A molecular sieve and a composite binder to obtain balls, and drying and roasting the balls to obtain matrix balls;
(2) Prewetting the matrix pellets, and then performing calcium exchange to obtain 5A molecular sieve pellets;
(3) Washing the 5A molecular sieve pellets with water, drying, and roasting to obtain a 5A molecular sieve adsorbent finished product;
Wherein the composite binder is a mixture of sodium metaaluminate and sodium silicate and/or silicic acid, and the silicon-aluminum molar ratio is 1.5-2.5.
According to the process of the present invention, the 4A molecular sieve may be used as the 4A molecular sieve typically used in the art for preparing 5A molecular sieve adsorbents.
According to the method of the present invention, the composite binder may be a mixture of sodium metaaluminate and sodium silicate, a mixture of sodium metaaluminate and silicic acid, or a mixture of sodium metaaluminate and sodium silicate and silicic acid. In addition, the content of impurities (e.g., iron oxide, nickel oxide, copper oxide, etc.) in the composite binder is preferably less than 90ppm.
From the viewpoint of further improving the adsorption performance of the obtained 5A molecular sieve adsorbent, the silica-alumina molar ratio of the composite binder is preferably 1.7 to 2.3.
The silica-alumina molar ratio of the composite binder may be, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, or 2.5.
The composite binder is preferably added in the form of an aqueous solution, preferably in which the total concentration of sodium metaaluminate and sodium silicate and/or silicic acid is 5 to 25% by weight, preferably 10 to 20% by weight.
According to the method of the invention, the aim of the invention can be achieved according to the technical scheme. On this basis, in order to further increase the normal paraffin adsorption amount of the prepared 5A molecular sieve adsorbent, the average crystal grain diameter of the 4A molecular sieve in the step (1) is preferably 0.01 to 2.0. Mu.m, and more preferably 0.5 to 0.9. Mu.m. The N-alkane adsorption capacity of the prepared 5A molecular sieve adsorbent can be improved by adopting the 4A molecular sieve with the average grain diameter to prepare the 5A molecular sieve adsorbent.
According to the process of the present invention, it is further preferred that the 4A molecular sieve of step (1) has a methanol adsorption of 160 to 190mg/g, more preferably 180 to 190mg/g.
According to the method of the present invention, preferably, the powder material containing the 4A molecular sieve and the composite binder in step (1) further contains an auxiliary agent (for example, may be a pore-forming agent), and the pore-forming agent is preferably one or more of lignin, sodium cellulose and sesbania powder. The pore-forming agent is added into the powder, so that the heap ratio of the 5A molecular sieve adsorbent can be adjusted, and the formation of secondary pores in the adsorbent is facilitated.
According to the method of the invention, the content of the 4A molecular sieve, the composite binder and the optional pore-forming agent in the powder is wide in the optional range. In a preferred embodiment of the present invention, the powder has a content of the 4A molecular sieve of 90 to 99.9 wt%, a content of the composite binder of 0.1 to 10 wt%, and a content of the pore-forming agent of 0 to 7 wt%. In another preferred embodiment of the present invention, the content of the 4A molecular sieve in the powder is 90 to 99 wt%, the content of the composite binder is 0.1 to 9 wt%, and the content of the pore-forming agent is 0.1 to 7 wt%. In the case of using the composite binder solution, the content of the composite binder is based on the weight of the composite binder solution.
In the present invention, the process for preparing the powder containing the 4A molecular sieve, the composite binder and the optional auxiliary agent may be carried out with reference to the existing 4A molecular sieve matrix pellet preparation method, for example, the 4A molecular sieve powder, the composite binder and the optional auxiliary agent powder may be mixed in a mixer (for example, a twin screw mixer) for 0.5 to 5 hours, preferably 2 to 3 hours. Those skilled in the art will appreciate that the present invention is not described herein.
The method for rolling ball forming of the powder containing the 4A molecular sieve, the composite binder and the optional auxiliary agent can be carried out by referring to the existing preparation method of the 4A molecular sieve matrix pellets, and can be carried out for example as follows: the powder containing the 4A molecular sieve, the composite binder and the optional auxiliary agent is fed into a ball-rolling pot (such as a sugar coating pot) and then the ball-rolling forming is carried out while adding water, wherein the preferable operation conditions in the ball-rolling pot comprise: the rotational speed is 30-40 r/min, the water adding speed is based on the water content of the total material of the rolling ball is increased by 2-6 wt% per hour, when the water content of the total material of the rolling ball reaches 45-50 wt%, the water adding is stopped, and then the rolling ball is continuously rotated to be molded for 1-5 hours, and the rotational speed is 40-100 r/min. For the present invention, it is preferable that the ball molding conditions are such that the particle diameter of the pellets obtained by ball molding is 0.1 to 0.7mm and the water content of the pellets is 43 to 45% by weight.
The drying and calcination of the pellets in step (1) according to the process of the present invention may be carried out using existing methods for forming 4A molecular sieve catalysts. Specifically, the drying in step (1) may be performed under the following conditions: the temperature is 80-150 ℃ and the time is 1-10 hours; preferably, the temperature is 100-130 ℃ for 1-5 hours. In addition, the firing may be performed under the following conditions: the temperature is 200-600 ℃ and the time is 1-5 hours; preferably, the temperature is 500-600 ℃ for 1-3 hours.
The object of the present invention can be achieved by ensuring that the matrix pellets are pre-wetted before being subjected to the calcium exchange according to the method of the present invention, and for the purpose of further increasing the normal alkane adsorption amount of the finally produced 5A molecular sieve adsorbent, it is preferable that the matrix pellets are pre-wetted in the step (2) under such conditions that the water content in the pre-wetted matrix pellets is 17 wt% or more, preferably 19 to 23 wt%.
According to the method of the invention, the pre-wetting method is not particularly required, the aim of the invention can be fulfilled as long as the water content in the pre-wetted matrix pellets is ensured to be more than 17 weight percent, and the existing pre-wetting method can be used for the invention. For the present invention, it is preferable that the pre-wetting in the step (2) is performed by pre-wetting the matrix pellets in a humidity environment for 1 to 10 hours, wherein the ambient humidity is preferably 10 to 100% rh, more preferably 70 to 80% rh. Wherein RH refers to relative humidity, and specifically refers to the percentage of the amount of water vapor contained in the air in the environment and the amount of saturated water vapor contained in the air under the same condition.
According to the method of the invention, the calcium exchange in the step (2) can be performed by referring to the existing 5A molecular sieve preparation method, and the final calcium exchange rate is required to be more than 80%.
According to the method of the invention, the container used for the calcium exchange is not particularly limited, and can be carried out in a kettle-type container or a column-type container, for example, and for the invention, the calcium exchange is preferably carried out in a column-type container.
According to the method of the present invention, the method of drying the 5A molecular sieve pellets in step (3) may be performed with reference to the existing 5A molecular sieve preparation method such that the water content of the 5A molecular sieve pellets is 17 wt% or less.
According to the method of the invention, the method for roasting the 5A molecular sieve pellets in the step (3) can be performed by referring to the existing preparation method of the 5A molecular sieve, however, the inventor of the invention finds that if the 5A molecular sieve pellets are roasted under a certain vacuum degree, the moisture separated out in the process of roasting the 5A molecular sieve pellets can be quickly taken away, so that the damage of high-temperature water vapor to the structure of the 5A molecular sieve can be effectively avoided, and the adsorption capacity of the adsorbent can be improved. Therefore, for the present invention, it is preferable that the 5A molecular sieve pellets in step (3) are subjected to vacuum calcination under vacuum degree- (10-100) kPa to activate dehydration, and more preferable that the conditions of the calcination are such that the water content of the 5A molecular sieve pellets after calcination is 3.5% by weight or less. For the present invention, the conditions for the calcination preferably include: the roasting temperature is 200-900 ℃, preferably 350-550 ℃; the vacuum degree of roasting is- (10-100) kPa, preferably- (80-95) kPa; the calcination time is 1 to 5 hours, preferably 2 to 3 hours.
The baking apparatus capable of satisfying the foregoing baking conditions may be, for example, a vacuum baking furnace or a vacuum oven. According to the method of the present invention, the present invention has no special requirement on the operating conditions of the roasting furnace, as long as the object of the present invention can be achieved.
In the present invention, the purpose of washing the 5A molecular sieve pellets in the step (3) is mainly to remove chloride ions by water washing, and as can be known by those skilled in the art, the present invention is not described herein, and the specific embodiments of the present invention are not emphasized.
In a second aspect, the invention provides a 5A molecular sieve adsorbent prepared by the method of the first aspect of the invention.
The 5A molecular sieve adsorbent prepared by the method has the n-hexane adsorption capacity of more than 125mg/g, preferably more than 135mg/g, for example 127-136mg/g.
In addition, the 5A molecular sieve adsorbent prepared by the method has a breakage rate of less than 9.1% under 250N.
The third party provides the application of the 5A molecular sieve adsorbent in the second aspect of the invention in the adsorption separation of normal paraffins, preferably in the adsorption of normal hexane.
In the present invention, the 5A molecular sieve adsorbent has an ignition loss of 5 wt% or less, preferably 2 to 4 wt% at 600 ℃.
In the invention, the water content of the 5A molecular sieve adsorbent is expressed by the ignition loss after 1.0 hour at 600 ℃, namely the ratio of the mass loss of the 5A molecular sieve adsorbent after ignition to the mass of the 5A molecular sieve adsorbent before ignition.
In the present invention, the diameter of the 5A molecular sieve adsorbent is preferably 0.1 to 0.7mm, more preferably 0.3 to 0.5mm.
In the invention, the adsorption quantity of the n-hexane is measured according to the industry standard Q/SH 349 551.
In the present invention, the calcium exchange rate refers to the percentage of sodium ions in the molecular sieve that are replaced by calcium ions, as measured by the industry standard Q/SH349550 method.
In the invention, the average grain diameter is measured by adopting a scanning electron microscope observation method.
In the invention, the method for measuring the strength of the adsorbent is shown in Chinese patent CN1261201C, and the lower the breaking rate is, the better the strength is, wherein the breaking rate is expressed under the pressure of 250N.
Example 1
(1) 200Kg of commercial 4A molecular sieve raw powder (the water content is 20 wt%, the average grain diameter is 0.7 mu m, the methanol adsorption amount is 185 mg/g), 10kg of sodium metaaluminate and sodium silicate composite binder solution (the total content of sodium metaaluminate and sodium silicate is 16 wt%, the silicon-aluminum molar ratio is 2), 5kg of sesbania powder pore-forming agent are put into a double-screw mixer to be mixed for 2 hours, 30kg of mixed material is taken out, the mixed material is put into a ball-rolling pot (sugar-coating pot) with the aperture of 1.0m, the ball-rolling forming is carried out to manufacture small balls (the operation conditions in the ball-rolling pot comprise that the rotating speed is controlled to be 35 r/min, the water adding speed is controlled to be 3-5 wt% based on the water content of the material per hour, when the final water content of the material reaches 45-50 wt%, then the rotating speed of the ball-rolling pot body is kept to be 50 r/min, the ball-rolling pot body is continuously rotated for 3-5 hours), when the ball length is 0.1-0.7mm, polishing treatment is carried out for 1-2 hours, and the ball-rolling forming sample with the water content of the ball sample of 0.43 mm is obtained; drying the pellets in an oven at 100 ℃ for 2 hours, roasting the pellets in a converter at 550 ℃ for 2 hours, and cooling the pellets to 20 ℃ to obtain the matrix pellets.
(2) Placing the matrix pellets in an environment with an air humidity of 70-80% RH so that the water content of the matrix pellets reaches 20% by weight; and then the prewetted matrix pellets are sent into a column reactor to be contacted with calcium chloride aqueous solution for calcium ion exchange, wherein the concentration of the calcium chloride aqueous solution is 0.5mol/L, the volume ratio of the calcium chloride aqueous solution to the 4A molecular sieve matrix pellets is 2, the contact time is 3.5 hours, the contact temperature is 95 ℃, and finally the calcium exchange rate of the 4A molecular sieve matrix pellets reaches 90 percent, so that the 5A molecular sieve pellets are obtained.
(3) Then washing the 5A molecular sieve pellets to remove chloride ions, and drying to reduce the water content of the 5A molecular sieve pellets to below 18 weight percent; finally, the mixture is put into a vacuum activation furnace (self-made by Nanjing catalyst Co., ltd.) for roasting to activate and dehydrate (wherein the volume of the vacuum furnace is controlled to be 1.2m 3, the temperature is 500 ℃, the vacuum degree is-90 kPa, and the roasting time is 2 hours), and the 5A molecular sieve microsphere adsorbent (the water content is reduced to be below 3.0 wt%, and the related properties such as the adsorption amount of n-hexane and the like are shown in Table 1) is obtained.
Example 2
Pellets of a 5A molecular sieve adsorbent were produced in the same manner as in example 1 except that the average crystal grain diameter of the 4A molecular sieve raw powder used in step (1) was 1.2 μm (water content: 20% by weight, methanol adsorption amount: 181 mg/g), and the other conditions were the same, to obtain 5A molecular sieve pellets adsorbent (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
Example 3
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1 except that the 4A molecular sieve raw powder used in step (1) had an average crystal grain diameter of 0.6 μm (water content: 21% by weight, methanol adsorption amount: 181 mg/g), and the substrate pellets were pre-wetted in step (2) under such conditions that the water content of the pre-wetted substrate pellets was 18% by weight, and the remaining conditions were the same, to obtain 5A molecular sieve pellet adsorbents (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
Example 4
Pellets of a 5A molecular sieve adsorbent were produced in the same manner as in example 1 except that the average crystal grain diameter of the 4A molecular sieve raw powder used in step (1) was 1.7 μm (water content: 21% by weight, methanol adsorption amount: 181 mg/g), and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
Example 5
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1 except that 7kg of the composite binder was used in step (1) and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Example 6
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 1.7, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Example 7
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 2.3, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Example 8
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 1.5, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Example 9
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 2.5, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Comparative example 1
Pellets of the 5A molecular sieve adsorbent were prepared as in example 1, except that the ion exchange was directly performed without prewetting in step (2), and the other conditions were the same, to obtain the 5A molecular sieve pellet adsorbent (the relevant properties such as the amount of n-hexane adsorbed are shown in Table 1).
Comparative example 2
Pellets of a 5A molecular sieve adsorbent were prepared as in example 1, except that the binder used in step (1) was sodium silicate alone, and the other conditions were the same, to give pellets of a 5A molecular sieve adsorbent (the relevant properties such as n-hexane adsorption amounts are shown in Table 1).
Comparative example 3
Pellets of the 5A molecular sieve adsorbent were prepared as in example 1, except that the binder used in step (1) was sodium metaaluminate alone, and the other conditions were the same, to give pellets of the 5A molecular sieve adsorbent (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
Comparative example 4
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 1.2, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
Comparative example 5
Pellets of a 5A molecular sieve adsorbent were prepared in the same manner as in example 1, except that the silica-alumina molar ratio of the composite binder in step (1) was 2.8, and the other conditions were the same, to obtain pellets of a 5A molecular sieve adsorbent (the relevant properties such as n-hexane adsorption amount are shown in Table 1).
TABLE 1
As can be seen from the results in the table, the 5A molecular sieve adsorbent pellets prepared according to the method of the present invention have an n-hexane adsorption level of 125mg/g or more, preferably 134mg/g or more, which is much higher and much higher in strength than the 5A molecular sieve adsorbent pellets prepared in the comparative example, which is not according to the method of the present invention.
Therefore, the 5A molecular sieve adsorbent pellets prepared by the method are particularly suitable for being used as normal alkane adsorbents.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (10)
1. The preparation method of the 5A molecular sieve adsorbent is characterized by comprising the following steps:
(1) Performing ball forming on powder containing a 4A molecular sieve and a composite binder to obtain balls, and drying and roasting the balls to obtain matrix balls;
(2) Prewetting the matrix pellets, and then performing calcium exchange to obtain 5A molecular sieve pellets;
(3) Washing the 5A molecular sieve pellets with water, drying, and roasting to obtain a 5A molecular sieve adsorbent;
Wherein the composite binder is a mixture of sodium metaaluminate and sodium silicate and/or silicic acid, and the molar ratio of silicon to aluminum is 1.5-2.5.
2. The method according to claim 1, wherein in the step (1), the composite binder has a silicon to aluminum molar ratio of 1.7 to 2.3.
3. The production process according to claim 1, wherein in step (1), the average crystal grain diameter of the 4A molecular sieve is 0.01 to 2.0 μm, preferably 0.5 to 0.9 μm;
Preferably, the methanol adsorption capacity of the 4A molecular sieve is 160-190mg/g, more preferably 180-190mg/g.
4. The production method according to claim 1, wherein in the step (1), the content of the 4A molecular sieve in the powder is 90 to 99.9 wt%, the content of the composite binder is 0.1 to 10 wt%, the content of the pore-forming agent is 0 to 7 wt%, more preferably, the content of the 4A molecular sieve in the powder is 90 to 99 wt%, the content of the composite binder is 0.1 to 9 wt%, and the content of the pore-forming agent is 0.1 to 7 wt%.
5. A method of preparation according to any one of claims 1 to 3, wherein in step (2) the pre-wetting is such that the water content of the pre-wetted matrix pellets is 17% by weight or more, preferably 19-23% by weight.
6. The production process according to any one of claims 1 to 3, wherein in the step (3), the calcination comprises vacuum-calcining the 5A molecular sieve pellets under a vacuum degree of- (10 to 100) kPa;
Preferably, the calcination conditions are such that the water content of the calcined 5A molecular sieve pellets is below 3.5 wt.%.
7. The production method according to claim 6, wherein in the step (3), the conditions of calcination include: the roasting temperature is 200-900 ℃, preferably 350-550 ℃; the vacuum degree of roasting is- (10-100) kPa, preferably- (80-95) kPa; the calcination time is 1 to 5 hours, preferably 2 to 3 hours.
8. A 5A molecular sieve adsorbent prepared by the method of any one of claims 1-7.
9. The 5A molecular sieve adsorbent of claim 8, wherein the n-hexane adsorption amount of the 5A molecular sieve adsorbent is 125mg/g or more, preferably 135mg/g or more.
10. Use of the 5A molecular sieve adsorbent of claim 8 or 9 in the adsorptive separation of normal paraffins, preferably in the adsorptive separation of normal hexane.
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