Alkene separation adsorbent and its preparation method

Abstract

The present invention provides an alkene-alkane separation adsorbent and a preparation method thereof. The preparation method comprises the following steps: Step S1, stirring and mixing raw materials including an aluminum source, a silicon source and water, then adjusting the pH value and performing two-stage hydrothermal crystallization treatment in sequence to obtain seeds; Step S2, subjecting the seeds to aging treatment and hydrothermal crystallization treatment in sequence to obtain 13X molecular sieve; and Step S3, mixing the 13X molecular sieve and an aqueous solution of a silicon source, then performing hydrothermal reaction, first calcination treatment, zinc deposition treatment, reduction treatment and second calcination treatment in sequence to obtain the alkene-alkane separation adsorbent. The alkene-alkane separation adsorbent prepared in this application has high selectivity, high adsorption capacity and easy regeneration performance.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular sieve separation adsorbents, and in particular, to an alkene-alkane separation adsorbent and a preparation method thereof. Background Art

[0002] As important chemical raw materials, olefins play an important role in the synthesis of rubber, plastics and other chemical products. Olefins usually coexist with alkanes in petrochemical products, and the effective separation of olefins and alkanes is a key step in the chemical production process. At present, the adsorption separation method is widely used in the separation of olefins and alkanes due to its low energy consumption, simple operation and other advantages. 13X molecular sieve is regarded as a promising alkene-alkane separation adsorbent due to its excellent adsorption performance and thermal stability. However, there is still room for improvement in the specificity and adsorption capacity of traditional 13X molecular sieve in the separation of olefins and alkanes. Summary of the Invention

[0003] The main object of the present invention is to provide an alkene-alkane separation adsorbent and a preparation method thereof, so as to solve the problem that the selectivity and separation efficiency of 13X molecular sieve in the separation of olefins and alkanes are relatively low in the prior art.

[0004] To achieve the above object, according to one aspect of the present invention, there is provided a preparation method of an alkene-alkane separation adsorbent, the preparation method comprising the following steps: Step S1, stirring and mixing raw materials including an aluminum source, a silicon source and water to obtain a mixture, and sequentially adjusting the pH value and performing two-stage hydrothermal crystallization treatment on the mixture to obtain seeds; Step S2, subjecting the seeds to aging treatment and hydrothermal crystallization treatment in sequence to obtain 13X molecular sieve; and Step S3, mixing the 13X molecular sieve and an aqueous solution of a silicon source, and then performing hydrothermal reaction, first calcination treatment, zinc deposition treatment, reduction treatment and second calcination treatment in sequence to obtain an alkene-alkane separation adsorbent.

[0005] Further, in the above step S1, the pH value is 8.5-12.5, preferably 11.8-12.2; and / or, the stirring and mixing rate is 200-800 rpm; and / or, the stirring and mixing temperature is 20-100 °C; and / or, the stirring and mixing time is 0.1-24 h.

[0006] Further, in the above step S1, the two-stage hydrothermal crystallization treatment includes a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment carried out in sequence. Among them, the temperature of the first-stage hydrothermal crystallization treatment is 20 to 60°C; and / or, the time of the first-stage hydrothermal crystallization treatment is 4 to 24 h; further, preferably, the temperature of the first-stage hydrothermal crystallization treatment is 35 to 45°C; and / or, the time of the first-stage hydrothermal crystallization treatment is 11 to 13 h; and / or, the temperature of the second-stage hydrothermal crystallization treatment is 80 to 120°C; and / or, the time of the second-stage hydrothermal crystallization treatment is 6 to 48 h; further, preferably, the temperature of the second-stage hydrothermal crystallization treatment is 90 to 100°C; and / or, the time of the second-stage hydrothermal crystallization treatment is 22 to 26 h; preferably, the temperature of the second-stage hydrothermal crystallization treatment is 50 to 60°C higher than the temperature of the first-stage hydrothermal crystallization treatment.

[0007] Further, in the above step S1, the silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate, and silicon powder; and / or, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate, and aluminum nitrate.

[0008] Further, in the above step S1, the seed crystal contains SiO 2 , Al 2 O 3 , Na 2 O and H 2 O. Among them, the molar ratio of SiO 2 to Al 2 O 3 is 0.01 to 6:1, and the molar ratio of Na 2 O, H 2 O to SiO 2 is 0.01 to 4.0:1.0 to 50.0:1.

[0009] Further, in the above step S2, the aging treatment is to add the seed crystal to polyvinylpyrrolidone and / or polyvinyl alcohol for aging; and / or, the temperature of the aging treatment is 20 to 100°C; and / or, the time of the aging treatment is 0.1 to 24 h; and / or, the temperature of the hydrothermal crystallization treatment is 60 to 105°C, and the time of the hydrothermal crystallization treatment is 0.1 to 36 h.

[0010] Further, in the above step S2, the 13X molecular sieve contains silicon and aluminum elements, and the molar ratio of silicon and aluminum elements is 2.2 to 2.9:1; and / or, the pore volume of the 13X molecular sieve is 0.3 to 0.5 cm 3 / g; and / or, the specific surface area of the 13X molecular sieve is 700 to 950 m 2 / g.

[0011] Further, in the above step S3, the mass ratio of the 13X molecular sieve to the volume of the silicon source aqueous solution is 50-100 g / L; and / or, the volume concentration of the silicon source aqueous solution is 0.5-10%.

[0012] Further, in the above step S3, the temperature of the hydrothermal reaction is 60-80 °C; and / or, the time of the hydrothermal reaction is 6-10 h; and / or, the temperature of the first calcination treatment is 550-800 °C; and / or, the time of the first calcination treatment is 3-10 h; and / or, the temperature of the second calcination treatment is 500-800 °C, and the time of the second calcination treatment is 4-10 h; and / or, the temperature of the zinc deposition treatment is 20-30 °C; and / or, the time of the zinc deposition treatment is 20-24 h; and / or, the temperature of the reduction treatment is 20-30 °C; and / or, the time of the reduction treatment is 10-12 h.

[0013] According to another aspect of the present invention, an alkene / alkane separation adsorbent is provided, and the alkene / alkane separation adsorbent is prepared by the foregoing preparation method.

[0014] Applying the technical solution of the present application, in steps S1 and S2, by controlling the pH value, crystallization temperature, raw material ratio, and two-stage crystallization process, a 13X molecular sieve with a high silica-alumina ratio, excellent specific surface area, and pore volume is prepared. The 13X molecular sieve is subjected to a series of hydrothermal reactions, first calcination treatment, zinc deposition treatment, reduction treatment, and second calcination treatment to prepare an alkene / alkane separation adsorbent with optimized structure and high activity. Therefore, the alkene / alkane separation adsorbent prepared by the present application has high selectivity, high adsorption capacity, and easy regeneration performance. Specific Embodiments

[0015] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0016] As analyzed in the background art of the present application, there is a problem in the prior art that the selectivity and separation efficiency of the 13X molecular sieve in the separation of olefins and alkanes are relatively low. To solve this problem, the present application provides an alkene / alkane separation adsorbent and a preparation method thereof.

[0017] In a typical embodiment of the present application, a method for preparing an alkene separation adsorbent is provided. The preparation method includes the following steps: Step S1, stirring and mixing raw materials including an aluminum source, a silicon source, and water to obtain a mixture, and sequentially adjusting the pH value and performing two-stage hydrothermal crystallization treatment on the mixture to obtain seeds; Step S2, subjecting the seeds to aging treatment and hydrothermal crystallization treatment in sequence to obtain 13X molecular sieve; and Step S3, mixing the 13X molecular sieve and an aqueous solution of a silicon source, and then performing hydrothermal reaction, first calcination treatment, zinc deposition treatment, reduction treatment, and second calcination treatment in sequence to obtain the alkene separation adsorbent.

[0018] In Step S1 and Step S2, by controlling the pH value, crystallization temperature, raw material ratio, and two-stage crystallization process, 13X molecular sieve with a high silicon-aluminum ratio, excellent specific surface area, and pore volume is prepared. By subjecting the 13X molecular sieve to a series of hydrothermal reaction, first calcination treatment, zinc deposition treatment, reduction treatment, and second calcination treatment, an alkene separation adsorbent with optimized structure and high activity is prepared. Therefore, the alkene separation adsorbent prepared in the present application has high selectivity, high adsorption capacity, and easy regeneration performance.

[0019] In order to promote the formation of 13X molecular sieve crystals, in an embodiment of the present application, preferably in the above Step S1, the pH value is 8.5 to 12.5, preferably 11.8 to 12.2; and / or, the stirring and mixing rate is 200 to 800 rpm; and / or, the stirring and mixing temperature is 20 to 100 °C; and / or, the stirring and mixing time is 0.1 to 24 h.

[0020] In order to improve the crystallization degree of the 13X molecular sieve, in an embodiment of the present application, preferably in the above Step S1, the two-stage hydrothermal crystallization treatment includes a first-stage hydrothermal crystallization treatment and a second-stage hydrothermal crystallization treatment performed in sequence. Among them, the temperature of the first-stage hydrothermal crystallization treatment is 20 to 60 °C; and / or, the time of the first-stage hydrothermal crystallization treatment is 4 to 24 h; further preferably, the temperature of the first-stage hydrothermal crystallization treatment is 35 to 45 °C; and / or, the time of the first-stage hydrothermal crystallization treatment is 11 to 13 h; and / or, the temperature of the second-stage hydrothermal crystallization treatment is 80 to 120 °C; and / or, the time of the second-stage hydrothermal crystallization treatment is 6 to 48 h; further preferably, the temperature of the second-stage hydrothermal crystallization treatment is 90 to 100 °C; and / or, the time of the second-stage hydrothermal crystallization treatment is 22 to 26 h; preferably, the temperature of the second-stage hydrothermal crystallization treatment is 50 to 60 °C higher than the temperature of the first-stage hydrothermal crystallization treatment; further preferably, the temperature of the first-stage hydrothermal crystallization treatment is 40 °C, and / or the time of the first-stage hydrothermal crystallization treatment is 12 h; the temperature of the second-stage hydrothermal crystallization treatment is 95 °C, and / or the time of the second-stage hydrothermal crystallization treatment is 24 h.

[0021] In addition, in order to further improve the mixing effect of the aluminum source, silicon source and water, the specific steps of preferably stirring and mixing the above raw materials of the aluminum source, silicon source and water include: stirring and mixing the silicon source and water, the temperature of the stirring and mixing is 20-60°C, the time of the stirring and mixing is 0.1-12 h, the rotation speed of the stirring and mixing is 200-800 rpm, to obtain a silicon-containing solution, and the concentration of the silicon-containing solution is 28%-99 wt%; stirring and mixing the aluminum source and water, the temperature of the stirring and mixing is 20-60°C, the time of the stirring and mixing is 0.1-12 h, the rotation speed of the stirring and mixing is 200-800 rpm, to obtain an aluminum-containing solution, and the concentration of the aluminum-containing solution is 28%-99 wt%, and after stirring and mixing the silicon-containing solution and the aluminum-containing solution, the pH value is adjusted successively.

[0022] Preferably, the above method for adjusting the pH value is to slowly add a solid base or an aqueous solution of a base to the mixed gel; preferably, the base is sodium hydroxide and / or potassium hydroxide. Preferably, after the hydrothermal crystallization treatment in the above step S2, the reaction product needs to be filtered and washed until neutral, and then dried at 80-120°C until there is no obvious weight loss to obtain 13X molecular sieve.

[0023] In one embodiment of the present application, in the above step S1, the silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate and silicon powder; and / or, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

[0024] Preferably, controlling the types of the silicon source and the aluminum source within the above range helps to enrich the material selectivity and reduce the cost of preparing the seed crystal.

[0025] In order to promote the formation of the 13X molecular sieve framework structure and improve its stability, in one embodiment of the present application, preferably, in the above step S1, the seed crystal contains SiO 2 , Al 2 O 3 , Na 2 O and H 2 O, wherein the molar ratio of SiO 2 to Al 2 O 3 is 0.01-6:1, and the molar ratio of Na 2 O, H 2 O to SiO 2 is 0.01-4.0:1.0-50.0:1.

[0026] To further promote the smooth formation of the 13X molecular sieve structure, in one embodiment of the present application, preferably in the above step S2, the aging treatment is to add the seed crystal into polyvinylpyrrolidone and / or polyvinyl alcohol for aging; and / or, the temperature of the aging treatment is 20-100 °C; and / or, the time of the aging treatment is 0.1-24 h; and / or, the temperature of the hydrothermal crystallization treatment is 60-105 °C, and the time of the hydrothermal crystallization treatment is 0.1-36 h.

[0027] Since polyvinylpyrrolidone and / or polyvinyl alcohol can be used as structure-directing agents and crystal growth regulators, aging under the above conditions helps to further assist crystallization, optimize the crystal form, and significantly improve the structural stability of the obtained molecular sieve.

[0028] In addition, preferably the aging process is carried out under stirring.

[0029] In one embodiment of the present application, in the above step S2, the 13X molecular sieve contains silicon and aluminum elements, and the molar ratio of silicon to aluminum elements is 2.2-2.9:1; and / or, the pore volume of the 13X molecular sieve is 0.3-0.5 cm 3 / g; and / or, the specific surface area of the 13X molecular sieve is 700-950 m 2 / g.

[0030] Preferably, the 13X molecular sieve prepared by steps S1 and S2 of the present application has the above properties. Among them, preferably the molar ratio of silicon to aluminum elements within the above range helps to improve the utilization rate of the silicon source in the raw materials; preferably the pore volume and specific surface area of the 13X molecular sieve are within the above ranges, which helps to provide more adsorption sites for the separation process of alkanes and alkenes and is beneficial to improving the flow and diffusion performance of alkane molecules and alkene molecules inside the molecular sieve.

[0031] To improve the preparation effect and efficiency of the alkene-alkane separation adsorbent, in one embodiment of the present application, preferably in the above step S3, the mass ratio of the 13X molecular sieve to the volume of the silicon source aqueous solution is 50-100 g / L; and / or, the volume concentration of the silicon source aqueous solution is 0.5-10%.

[0032] In order to further improve the selectivity and separation efficiency of the alkene-alkane separation adsorbent, in one embodiment of the present application, preferably in the above step S3, the temperature of the hydrothermal reaction is 60-80 °C; and / or, the time of the hydrothermal reaction is 6-10 h; and / or, the temperature of the first calcination treatment is 550-800 °C; and / or, the time of the first calcination treatment is 3-10 h; and / or, the temperature of the second calcination treatment is 500-800 °C, and the time of the second calcination treatment is 4-10 h; and / or, the temperature of the zinc deposition treatment is 20-30 °C; and / or, the time of the zinc deposition treatment is 20-24 h; and / or, the temperature of the reduction treatment is 20-30 °C; and / or, the time of the reduction treatment is 10-12 h.

[0033] In order to further improve the preparation efficiency of the alkene-alkane separation adsorbent, in one embodiment of the present application, preferably in the above step S3, after mixing 13X molecular sieve and the silicon source aqueous solution, a second hydrothermal reaction and a first calcination treatment are carried out in sequence. The product after the first calcination treatment is put into a zinc-containing solution for zinc deposition treatment, and the product after the zinc deposition treatment is put into a reduction solution for reduction treatment; the product after the reduction treatment is subjected to a second calcination treatment to obtain the alkene-alkane separation adsorbent.

[0034] The above zinc-containing solution is a zinc nitrate solution; the reduction solution is a sodium borohydride solution; the solute in the silicon source aqueous solution is selected from any one or more of silica sol, tetraethyl orthosilicate and silicon powder. Preferably, the concentration of the above zinc-containing solution is 50-60 g / L, and / or the concentration of the reduction solution is 20-30 g / L;

[0035] In another typical embodiment of the present application, an alkene-alkane separation adsorbent is provided, and the alkene-alkane separation adsorbent is prepared by the aforementioned preparation method.

[0036] The alkene-alkane separation adsorbent obtained by the preparation method of the present application has high activity, high selectivity, high adsorption capacity, high diffusion performance and easy regeneration performance. Applying the alkene-alkane separation adsorbent to the separation of olefins and alkanes helps to improve the separation efficiency of olefins and alkanes.

[0037] The beneficial effects of the present application will be further described below in conjunction with embodiments.

[0038] Example 1

[0039] (1) Dissolve 21.0 g of silica sol (mass fraction 30%) in 36.0 g of deionized water, and after pre-treating at 25 °C for 1 hour in a sealed reactor, obtain a silicon-containing material; dissolve 24 g of aluminum sulfate in 18.0 g of deionized water, and stir at 25 °C for 1 h to obtain an aluminum-containing material; slowly add the aluminum-containing material dropwise to the silicon-containing material (the dropping rate is completed in 0.8 h), continue stirring at 60 °C for 8 h, and the stirring and mixing rate is 500 rpm to obtain a mixture gel; dissolve 6.74 g of sodium hydroxide in 36 g of deionized water dispersion and add it to the mixture gel until the pH value is 12 to obtain a gel slurrying solution, place it in a hydrothermal reactor, and perform two-stage temperature-controlled crystallization. The first-stage crystallization temperature is 40 °C and the time is 12 hours, and the second-stage crystallization temperature is 95 °C and the time is 24 hours to obtain 13X seeds (where the molar ratio of each component is: SiO 2 / Al 2 O 3 =1.5:1, Na 2 O / SiO 2 =1.6:1, H 2 O / SiO 2 =32:1).

[0040] (2) Mix the above 13X seeds with 1 g of polyvinyl alcohol, then continue stirring and aging at 70 °C for 15 h, then place it in a hydrothermal reactor, and perform final crystallization at a crystallization temperature of 105 °C for 16 h. Filter and wash the obtained product until the pH is 7, and dry at 90 °C to obtain 13X molecular sieve, where the molar ratio of silicon element and aluminum element in the 13X molecular sieve is 2.60:1; the pore volume of the 13X molecular sieve is 0.4603 cm 3 / g, and the specific surface area of the 13X molecular sieve is 879.2 m 2 / g.

[0041] (3) Take 50 g of 13X molecular sieve and put it into 1 L of tetraethyl orthosilicate aqueous solution with a volume ratio of 0.5% for mixing. Hydrothermally react the mixed solution at 60 °C for 6 hours. Filter, wash, and dry the reacted solution in sequence to obtain a solid. Calcinate the solid at 550 °C for 3 hours to obtain a calcined solid; dissolve 60 g of zinc nitrate in 1 L of deionized water to form a zinc nitrate aqueous solution, add 30 g of the calcined solid to the zinc nitrate aqueous solution to form a mixed solution, let the mixed solution stand for 24 hours, and then filter, wash, and dry the standing mixed solution in sequence to obtain a solid. Dissolve 30 g of NaBH 4 in 1 L of deionized water to form a NaBH 4 aqueous solution, and add 25 g of the solid to the NaBH 4In an aqueous solution, react for 12 hours. Filter, wash, and dry the reacted solution to obtain a solid. Finally, calcine the solid in an air atmosphere at 500 °C for 4 hours and vacuum dry it at room temperature for 24 hours to obtain an alkene separation adsorbent.

[0042] Example 2

[0043] The difference from Example 1 is that: (1) Dissolve 1 g of silicon powder in 18 g of deionized water, and pre-treat it at 25 °C for 1 hour in a closed reactor to obtain a silicon-containing material. At the same time, dissolve 12 g of aluminum nitrate in 18.0 g of deionized water and stir it at 35 °C for 1 hour to prepare an aluminum-containing material. Slowly add the prepared aluminum-containing material dropwise to the silicon-containing material (the dropping rate is completed in 0.6 h), and continue to stir at 50 °C for 6 hours to obtain a mixture gel; dissolve 2 g of sodium hydroxide in 36 g of deionized water to prepare a dispersion, and add it to the mixture gel until the pH value reaches 11.8 to obtain a gel slurrying solution, and then transfer it to a hydrothermal reactor to perform a two-stage temperature-controlled crystallization process: the first-stage crystallization temperature is set at 50 °C for 14 hours; the second-stage crystallization temperature is controlled at 100 °C for 18 hours to obtain 13X seeds (where the molar ratio of each component is: SiO 2 / Al 2 O 3 = 0.6:1, Na 2 O / SiO 2 = 3:1, H 2 O / SiO 2 = 20:1).

[0044] (2) Mix the above 13X seeds with 1 g of polyvinylpyrrolidone, age at 20 °C for 0.1 h, then perform hydrothermal crystallization at 60 °C for 0.1 h. Filter, wash the hydrothermal seeds to neutral, and dry them to constant weight at 80 °C to obtain 13X molecular sieve, where the molar ratio of silicon element and aluminum element in the 13X molecular sieve is 2.42:1; the pore volume of the 13X molecular sieve is 0.4449 cm 3 / g, and the specific surface area of the 13X molecular sieve is 871.6 m 2 / g.

[0045] (3) Take 50 g of 13X molecular sieve and put it into 1 L of an aqueous solution of tetraethyl orthosilicate with a volume ratio of 0.5%, and mix. Hydrothermally react the mixed solution at 60 °C for 6 hours. Filter, wash, and dry the reacted solution in sequence to obtain a solid. Calcinate the solid at 550 °C for 3 hours to obtain a calcined solid; dissolve 60 g of zinc nitrate in 1 L of deionized water to form an aqueous zinc nitrate solution, add 30 g of the calcined solid to the aqueous zinc nitrate solution to form a mixed solution, let the mixed solution stand for 24 hours, and then filter, wash, and dry the standing mixed solution in sequence to obtain a solid. Dissolve 30 g of NaBH 4 in 1 L of deionized water to form an NaBH 4 aqueous solution, add 25 g of the solid to the NaBH 4 aqueous solution, react for 12 hours, filter, wash, and dry the reacted solution to obtain a solid. Finally, calcinate the solid in an air atmosphere at 500 °C for 4 hours and vacuum dry at room temperature for 24 hours to obtain an alkene separation adsorbent.

[0046] Example 3

[0047] The difference from Example 1 is that: (1) Dissolve 0.17 g of silicon powder in 6 g of deionized water, and pre-treat it at 25 °C for 1 hour in a closed reaction kettle to obtain a silicon-containing material; at the same time, dissolve 12 g of aluminum nitrate in 18.0 g of deionized water and stir at 35 °C for 1 hour to prepare an aluminum-containing material solution. Slowly add the aluminum-containing material to the silicon-containing material (the dropping rate is completed in 1 h), and stir at 100 °C for 24 hours to obtain a mixture gel; dissolve 0.9 g of sodium hydroxide in 6 g of deionized water to prepare a dispersion, and add it to the mixture gel until the pH value is 12.5 to obtain a gelled slurried solution, and then transfer it to a hydrothermal reaction kettle for two-stage crystallization. First, crystallize at 60 °C for 24 hours, and then raise the temperature to 120 °C for a crystallization reaction of 48 hours to obtain 13X seeds (where the molar ratio of each component is: SiO 2 / Al 2 O 3 = 0.1:1, Na 2 O / SiO 2 = 4:1, H 2 O / SiO 2 = 1:1).

[0048] (2) Mix the above 13X seeds with 1 g of polyvinyl alcohol, age at 100 °C for 24 h, and then carry out hydrothermal crystallization treatment at 105 °C for 36 h. Filter, wash the hydrothermal seeds to neutral, and dry to constant weight at 120 °C to obtain 13X molecular sieve, where the molar ratio of silicon element and aluminum element in the 13X molecular sieve is 2.25:1; the pore volume of the 13X molecular sieve is 0.3743 cm3 / g, the specific surface area of the 13X molecular sieve is 790.2 m 2 / g, and finally an alkene separation adsorbent is obtained.

[0049] Example 4

[0050] The difference from Example 1 is that (1) 14.650 g of tetraethyl orthosilicate and 36 g of deionized water are mixed in a volume ratio of 1:1, and after pretreatment at 25 °C for 1 hour in a closed reaction kettle, a silicon-containing material is obtained. At the same time, 12 g of aluminum nitrate is dissolved in 18.0 g of deionized water and stirred at 35 °C for 1 hour to obtain an aluminum-containing material. Then, the aluminum-containing material is gradually added dropwise to the silicon-containing material (the dropping rate is completed in 0.5 hour), and the mixture is stirred at 20 °C for 0.1 hour to prepare a mixture gel; 0.56 g of sodium hydroxide is dissolved in 6 g of deionized water as a dispersion liquid, and slowly poured into the mixture gel until the pH value is 8.5 to obtain a gel slurrying solution, and then it is transferred to a hydrothermal reaction kettle for staged crystallization reaction: first, the crystallization temperature is set at 20 °C for 4 hours; then it is raised to 80 °C and the crystallization is maintained for 6 hours to obtain 13X seeds (where the molar ratio of each component is: SiO 2 / Al 2 O 3 = 2.5:1, Na 2 O / SiO 2 = 0.1:1, H 2 O / SiO 2 = 40:1), and finally an alkene separation adsorbent is obtained, where the molar ratio of silicon element to aluminum element in the 13X molecular sieve is 2.89:1; the pore volume of the 13X molecular sieve is 0.4002 cm 3 / g, and the specific surface area of the 13X molecular sieve is 804.3 m 2 / g.

[0051] Example 5

[0052] The difference from Example 1 is that the pH value is 11.8, and finally an alkene separation adsorbent is obtained.

[0053] Example 6

[0054] The difference from Example 1 is that the pH value is 12.2, and finally an alkene separation adsorbent is obtained.

[0055] Example 7

[0056] The difference from Example 1 is that the pH value is 8.5, and finally an alkene separation adsorbent is obtained.

[0057] Example 8

[0058] It is different from Example 1 in that the pH value is 12.5, and finally an alkane-alkene separation adsorbent is obtained.

[0059] Example 9

[0060] It is different from Example 1 in that the pH value is 13, and finally an alkane-alkene separation adsorbent is obtained.

[0061] Example 10

[0062] It is different from Example 1 in that the temperature of the first-stage hydrothermal crystallization treatment is 35 °C, the time of the first-stage hydrothermal crystallization treatment is 11 h, the temperature of the second-stage hydrothermal crystallization treatment is 90 °C, and the time of the second-stage hydrothermal crystallization treatment is 26 h. Finally, an alkane-alkene separation adsorbent is obtained.

[0063] Example 11

[0064] It is different from Example 1 in that the temperature of the first-stage hydrothermal crystallization treatment is 45 °C, the time of the first-stage hydrothermal crystallization treatment is 13 h, the temperature of the second-stage hydrothermal crystallization treatment is 100 °C, and the time of the second-stage hydrothermal crystallization treatment is 22 h. Finally, an alkane-alkene separation adsorbent is obtained.

[0065] Example 12

[0066] It is different from Example 1 in that the temperature of the first-stage hydrothermal crystallization treatment is 20 °C, the time of the first-stage hydrothermal crystallization treatment is 4 h, the temperature of the second-stage hydrothermal crystallization treatment is 80 °C, and the time of the second-stage hydrothermal crystallization treatment is 6 h. Finally, an alkane-alkene separation adsorbent is obtained.

[0067] Example 13

[0068] It is different from Example 1 in that the temperature of the first-stage hydrothermal crystallization treatment is 60 °C, the time of the first-stage hydrothermal crystallization treatment is 24 h, the temperature of the second-stage hydrothermal crystallization treatment is 120 °C, and the time of the second-stage hydrothermal crystallization treatment is 48 h. Finally, an alkane-alkene separation adsorbent is obtained.

[0069] Example 14

[0070] It is different from Example 1 in that the temperature of the first-stage hydrothermal crystallization treatment is 70 °C, the time of the first-stage hydrothermal crystallization treatment is 25 h, the temperature of the second-stage hydrothermal crystallization treatment is 130 °C, and the time of the second-stage hydrothermal crystallization treatment is 50 h. Finally, an alkane-alkene separation adsorbent is obtained.

[0071] Comparative Example 1

[0072] It is different from Example 1 in that the commonly used 13X molecular sieve on the market (Shimadzu SGLC Molecular Sieve 13X) is used for the preparation of the alkane-alkene separation adsorbent, and finally an alkane-alkene separation adsorbent is obtained.

[0073] Testing method

[0074] The alkene - alkane separation adsorbents obtained from the above - mentioned examples and comparative examples were subjected to a fixed - bed adsorption experiment: A mixture of alkenes and alkanes (including C6, C7, and C8 components, with an alkene content of 60%) was passed through a fixed - bed containing the adsorbent (the mass ratio of the adsorbent to the alkene - alkane mixture was 1:10), and the change in the concentration of the alkene - alkane mixture passing through the bed layer was monitored to determine the adsorption performance of the adsorbent for a specific alkene - alkane mixture. The results of the selectivity of alkenes and the purity of alkenes are shown in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] From the above description, it can be seen that the above - mentioned examples of the present invention have achieved the following technical effects:

[0079] In steps S1 and S2, by controlling the pH value, crystallization temperature, raw material ratio, and the two - stage crystallization process, a 13X molecular sieve with a high silica - alumina ratio, excellent specific surface area, and pore volume was prepared. By subjecting this 13X molecular sieve to a series of hydrothermal reactions, a first calcination treatment, a zinc deposition treatment, a reduction treatment, and a second calcination treatment, an alkene - alkane separation adsorbent with an optimized structure and high activity was prepared. Therefore, the alkene - alkane separation adsorbent prepared in this application has high selectivity, high adsorption capacity, and easy regeneration performance.

[0080] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing an alkane-alkene separation adsorbent, characterized in that: The preparation method comprises the following steps: Step S1, stirring and mixing raw materials including an aluminum source, a silicon source and water to obtain a mixture, and sequentially performing pH adjustment and two-stage hydrothermal crystallization treatment on the mixture to obtain seed crystals; Step S2, subjecting the seed crystals to an aging treatment and a hydrothermal crystallization treatment in sequence to obtain a 13X molecular sieve; and Step S3, mixing the 13X molecular sieve and the silicon source aqueous solution and sequentially performing a hydrothermal reaction, a first calcination treatment, a zinc deposition treatment, a reduction treatment, and a second calcination treatment to obtain an alkane-olefin separation adsorbent; In the step S1, the pH value is 8.5-12.5; the two-stage hydrothermal crystallization treatment includes a first stage hydrothermal crystallization treatment and a second stage hydrothermal crystallization treatment performed sequentially, wherein the temperature of the first stage hydrothermal crystallization treatment is 20-60° C. and the time is 4-24 hours; the temperature of the second stage hydrothermal crystallization treatment is 80-120° C. and the time is 6-48 hours; In the step S2, the aging treatment is to add the seed crystals to polyvinyl pyrrolidone and / or polyvinyl alcohol for aging; In step S3, the temperature of the first calcination treatment is 550-800°C, and the time is 3-10 hours; the temperature of the second calcination treatment is 500-800°C, and the time is 4-10 hours; the temperature of the zinc deposition treatment is 20-30°C, and the time is 20-24 hours; the temperature of the reduction treatment is 20-30°C, and the time is 10-12 hours.

2. The preparation method according to claim 1, characterized in that: In the step S1, the pH value is 11.8-12.2; and / or the stirring and mixing speed is 200-800 rpm; and / or the stirring and mixing temperature is 20-100° C.; and / or the stirring and mixing time is 0.1-24 h.

3. The preparation method according to claim 1 or 2, characterized in that: In step S1, the temperature of the first hydrothermal crystallization treatment is 35-45° C.; and / or the time of the first hydrothermal crystallization treatment is 11-13 hours; And / or, the temperature of the second hydrothermal crystallization treatment is 90-100° C.; and / or, the time of the second hydrothermal crystallization treatment is 22-26 hours.

4. The preparation method according to claim 3, characterized in that: In the step S1, the temperature of the second hydrothermal crystallization treatment is 50-60° C. higher than the temperature of the first hydrothermal crystallization treatment.

5. The preparation method according to claim 1 or 2, characterized in that: In the step S1, the silicon source is selected from any one or more of silica sol, tetraethyl orthosilicate and silicon powder; And / or, the aluminum source is selected from any one or more of sodium aluminate, pseudo-boehmite, aluminum sulfate and aluminum nitrate.

6. The preparation method according to claim 1 or 2, characterized in that: In the step S1, the seed crystal contains SiO2, Al2O3, Na2O and H2O, wherein the molar ratio of the SiO2 to the Al2O3 is 0.01-6:1, and the molar ratio of the Na2O, the H2O and the SiO2 is 0.01-4.0:1.0-50.0:

1.

7. The preparation method according to claim 1 or 2, characterized in that: In step S2, the temperature of the aging treatment is 20-100°C; and / or, the time of the aging treatment is 0.1-24h; and / or, the temperature of the hydrothermal crystallization treatment is 60-105°C, and the time of the hydrothermal crystallization treatment is 0.1-36h.

8. The preparation method according to claim 1 or 2, characterized in that: In step S2, the 13X molecular sieve contains silicon and aluminum, and the molar ratio of the silicon to the aluminum is 2.2-2.9:1; and / or the pore volume of the 13X molecular sieve is 0.3-0.5 cm 3 / g; and / or, the specific surface area of ​​the 13X molecular sieve is 700-950m 2 / g.

9. The preparation method according to claim 1 or 2, characterized in that: In the step S3, the ratio of the mass of the 13X molecular sieve to the volume of the silicon source aqueous solution is 50-100 g / L; and / or the volume concentration of the silicon source aqueous solution is 0.5-10%.

10. The preparation method according to claim 1 or 2, characterized in that: In step S3, the temperature of the hydrothermal reaction is 60-80° C.; and / or the time of the hydrothermal reaction is 6-10 hours.

11. An alkane-alkene separation adsorbent, characterized in that: The alkane-olefin separation adsorbent is prepared by the preparation method according to any one of claims 1 to 10.

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