A process for the preparation of an alkenyl adsorbent from spent catalyst

Abstract

This invention discloses a method for preparing an alkane-alkene separation adsorbent from spent catalyst. Based on 13X molecular sieve, the method involves hydrothermal reaction, zinc source solution treatment, reduction reaction, and calcination to prepare an alkane-alkene separation adsorbent with optimized structure and high activity. Furthermore, a method for preparing 13X molecular sieve is proposed. This method first involves slowly adding aluminum-containing materials to silicon-containing materials and stirring to form a gel-like mixture. After adjusting the pH, the mixture undergoes segmented hydrothermal crystallization to obtain a crystallized product. The spent catalyst is then subjected to aluminum and silicon dissolution treatments to obtain a silicon-rich liquid and an aluminum-rich liquid. These two liquids are mixed to obtain a gel-like mother liquor. The crystallized product is added to this mother liquor, and after aging and hydrothermal crystallization, the 13X molecular sieve is finally obtained. The adsorbent prepared by this invention exhibits high selectivity, high adsorption capacity, and easy regeneration, providing a novel and efficient solution for the efficient separation of alkane-alkene and alkane-alkane mixtures.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis, specifically relating to a method for preparing alkane adsorbents from spent catalysts. Background Technology

[0002] Alkanes and alkenes are important chemical raw materials, playing a crucial role in the synthesis of rubber, plastics, and other chemical products. Alkanes and alkenes often coexist in petrochemical products, and their effective separation is a key step in chemical production. Currently, adsorption methods are widely used for alkane and alkene separation due to their low energy consumption and ease of operation. 13X molecular sieves are considered a promising adsorbent for alkane and alkene separation due to their excellent adsorption performance and thermal stability. However, there is still room for improvement in the specificity and adsorption capacity of traditional 13X molecular sieves for alkane and alkene separation. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for preparing alkane and olefin adsorbents from spent catalysts:

[0004] A method for preparing alkane adsorbents from spent catalysts, characterized by: subjecting a 13X molecular sieve to a hydrothermal reaction with a certain silicon source solution; calcining the molecular sieve after the hydrothermal reaction; immersing the calcined molecular sieve in a zinc source solution; filtering, washing, and drying the sieve; reacting the molecular sieve with a reducing agent solution, wherein the reducing agent is sodium borohydride (NaBH4) dissolved in deionized water; filtering, washing, and drying the reacted molecular sieve again; subjecting the molecular sieve to a final calcination treatment; and vacuum drying the calcined molecular sieve at room temperature to obtain the alkane adsorbent.

[0005] The preparation method of the 13X molecular sieve of the present invention includes the following:

[0006] (1) A silicon source and water are mixed evenly to obtain a silicon-containing material, and an aluminum source and water are mixed evenly to obtain an aluminum-containing material;

[0007] (2) The aluminum-containing material is slowly added to the silicon-containing material and stirred for a period of time to obtain a mixture gel. The pH value of the mixture gel is adjusted to 8.5-12.5, and then a two-stage hydrothermal crystallization treatment is carried out to obtain the crystallized product.

[0008] (3) The material containing molecular sieve is subjected to aluminum and silicon dissolution treatment to obtain silicon-rich liquid and aluminum-rich liquid, and the two are mixed to obtain gel-like mother liquor.

[0009] (4) The crystallized product of step (2) is added to the gel mother liquor of step (3) for aging treatment, and then hydrothermal crystallization treatment is carried out. The reaction product is filtered, washed, and then dried to obtain 13X molecular sieve.

[0010] In the method of this invention, the silicon source in step (1) is selected from one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica. The mixing process of the silicon source and water is generally carried out at 20-60°C for 0.1-12 hours, with the stirring speed maintained at 200-800 rpm, to obtain a silicon-containing material, the concentration of which is generally 28%-99 wt%.

[0011] In the method of this invention, the aluminum source in step (1) is selected from one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate. The mixing process of the aluminum source and water is generally carried out at 20-60°C for 0.1-12 hours, and the stirring speed is preferably 200-800 rpm, to obtain an aluminum-containing material with a concentration of 15%-99% wt%.

[0012] In the method of the present invention, the stirring conditions described in step (2) are generally stirred at 20 to 100°C for 0.1 to 24 hours to obtain a mixture gel.

[0013] In the method of the present invention, the pH adjustment method described in step (2) can be achieved by slowly adding a solid alkali or an aqueous solution of alkali to the gel solution A. Preferably, the pH value is 11.9-12.1.

[0014] In the method of this invention, the two-stage crystallization conditions in step (2) are as follows: the first-stage crystallization temperature is 20–60°C, and the crystallization time is 4–24 h; the second-stage crystallization temperature is 80–120°C, and the crystallization time is 6–48 h; crystallization is generally carried out in a hydrothermal reactor; the second stage is 20°C higher than the first stage.

[0015] In the method of the present invention, the molar ratios of the components in the crystallized product obtained in step (2) are SiO2 / Al2O3 = (0.1~2.5):1, Na2O / SiO2 = (0.1~4.0):1, and H2O / SiO2 = (1.0~40.0):1.

[0016] By precisely controlling the pH, the temperature and time of the two-stage crystallization, and the raw material ratio, the synergistic effect can be used to regulate the pore volume and specific surface area, and molecular sieves with suitable pore volume and specific surface area can be prepared as needed.

[0017] In the method of the present invention, the molecular sieve-containing material in step (3) is selected from one or more of the following: waste Z-5 molecular sieve catalyst, waste MTO catalyst, waste molecular sieve adsorbent, fly ash, waste FCC catalyst, and waste VOC adsorbent.

[0018] In the method of the present invention, the aluminum dissolution and silicon dissolution processes in step (3) are as follows: the molecular sieve material is ground to a sample of less than 200 mesh, mixed with NaCO3 at a mass ratio of 1:0.5 to 1:5, and calcined at 550-800℃ for 60-120 min. Then, the calcined product is dissolved and filtered with a monobasic acid of 10%-35% by mass to obtain an aluminum-rich liquid. The residue obtained is mixed with NaOH:H2O at a mass ratio of 1.5-100:40-60:50-400, stirred and mixed evenly, and filtered to obtain a silicon-rich liquid. Finally, the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor. The molar ratio of each component in the gel-like mother liquor is: SiO2 / Al2O3 = 0.5-6.0:1, Na2O / SiO2 = 0.5-6.0:1, H2O / SiO2 = 10-100:1.

[0019] In the method of the present invention, the amount of crystallized product added in step (4) accounts for 5wt%-20wt% of the gel mother liquor.

[0020] In the method of the present invention, the aging conditions in step (4) are: aging temperature of 20 to 100°C, aging time of 0.1 to 24 hours, and the aging process is generally carried out under stirring conditions.

[0021] In the method of the present invention, the hydrothermal crystallization conditions in step (4) are: crystallization temperature of 60-105℃ and crystallization time of 0.1-36h.

[0022] In the method of the present invention, step (4) involves filtering and washing the reaction product until it is neutral, and then drying it at 80-120°C until there is no significant weight loss to obtain 13X molecular sieve.

[0023] The preferred pH value is 11.8-12.2. For the two-stage crystallization, the preferred temperature for the first stage is 35-45℃, and the preferred time is 11-13 hours; the preferred temperature for the second stage is 90-100℃, and the preferred time is 22-26 hours. The temperature of the second stage is 50-60℃ higher than that of the first stage. The molar ratio of the raw materials is SiO2 / Al2O3.

[0024] =(4.6-5.0):1, Na2O / SiO2=(1.8-2.0):1, H2O / SiO2=40-50:1,

[0025] Long-term experiments have shown that by precisely controlling the pH, crystallization temperature, and raw material ratio, with a pH of 12, a first-stage crystallization temperature of 40℃ for 12 hours, a second-stage crystallization temperature of 95℃ for 24 hours, and SiO2 / Al2O3 = 4.7:1, Na2O / SiO2 = 1.95:1, and H2O / SiO2 = 44:1, these ratios can be used to control the uniform arrangement of pores, the specific surface area, and the pore capacity, thus preparing a high-performance molecular sieve.

[0026] The beneficial effects of this invention are as follows:

[0027] The 13X molecular sieve prepared by this invention has the following properties: a silica-to-alumina ratio of 2.2–2.9 and a pore volume of 0.3 cm³. 3 / g~0.5cm 3 / g, specific surface area 700m² 2 / g~950m 2 / g. The 13X molecular sieve prepared by this invention has a high silicon-to-aluminum ratio, high silicon source utilization, and good selectivity. It can be controlled according to different adsorbed molecules, providing more adsorption sites, introducing mesoporous channels, and increasing the pore volume inside the molecular sieve crystal, thereby significantly reducing the carbon deposition rate of the molecular sieve and improving the diffusion performance of the adsorbent. The alkane-alkene separation adsorbent prepared from this molecular sieve has high selectivity and high adsorption capacity, and can effectively separate alkanes and alkanes mixtures. Detailed Implementation

[0028] The present invention will be described in detail below through embodiments. Each embodiment only lists key technical indicators, but the present invention is not limited to these embodiments.

[0029] Preparation of alkane-alkene separation adsorbent:

[0030] 50 g of 13X molecular sieve was placed in a solution containing 1 L of 0.5% (v / v) tetraethyl orthosilicate (TEOS, 5 mL TEOS added to 995 mL of deionized water) and hydrothermally reacted at 60 °C for 6 hours. The treated molecular sieve was then calcined at 550 °C for 3 hours. 36.16 g of zinc nitrate was dissolved in 1 L of deionized water to form a solution, and the calcined molecular sieve was immersed in this solution for 18 hours. Then, it was filtered, washed, and dried. 11.4 g of NaBH4 was dissolved in 1 L of deionized water to form a solution, and the dried molecular sieve solution was added to the solution and reacted for 6 hours. It was then filtered, washed, and dried again. Finally, the dried molecular sieve was calcined at 500 °C in air for 4 hours. It was then vacuum dried at room temperature for 24 hours to obtain the final alkane adsorbent.

[0031] Preparation of 13X molecular sieve:

[0032] Example 1:

[0033] 21.0 g of silica sol (30% by mass) was dissolved in 36.0 g of deionized water and pretreated in a sealed reactor at 25 °C and 500 rpm for 1 hour to obtain a dispersed aqueous solution of the silicon source. 24 g of aluminum sulfate was dissolved in 18.0 g of deionized water and stirred at 25 °C and 500 rpm for 1 hour to obtain a dispersed aqueous solution of the aluminum source. The aqueous solution of the aluminum source was slowly added dropwise to the aqueous solution of the silicon source, and stirring was continued at 60 °C for 8 hours to obtain a gel solution. 6.74 g of sodium hydroxide was dissolved in 36 g of deionized water dispersion and added to the gel solution, maintaining the pH at 12.2. The resulting gel solution was placed in a hydrothermal reactor for two-stage temperature-controlled crystallization: the first stage crystallization was at 40 °C for 12 hours, and the second stage crystallization was at 95 °C for 24 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution. Waste Z-5 molecular sieve catalyst was mixed with NaCO3 at a mass ratio of 1:1 and calcined at 700℃ for 90 min. The calcined product was then dissolved with a 20% monobasic acid and filtered to obtain an aluminum-rich liquid and an aluminum-dissolving filter residue. The aluminum-dissolving filter residue was mixed with NaOH and H2O at a mass ratio of 50:50:200 and filtered to obtain a silicon-rich liquid. The silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor. Seed crystals of a certain mass ratio were added to the gel-like mother liquor, and then aging and crystallization treatments were carried out sequentially. The aging temperature was 60℃ for 12 h, and the crystallization temperature was 80℃ for 18 h. After drying, 13X molecular sieve was obtained.

[0034] Example 2: 1g of silicon powder was dissolved in 18g of deionized water and pretreated in a sealed reactor at 25°C and 500rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35°C and 500rpm for 1 hour to prepare an aluminum source dispersed phase aqueous solution. The prepared aluminum source aqueous solution was slowly added dropwise to the silicon source aqueous solution, and stirring was continued at 50°C for 6 hours to obtain a gel solution. 2g of sodium hydroxide was dissolved in 36g of deionized water to prepare a dispersion, which was slowly added to the gel solution, controlling the pH value at 11.8. The mixed gel solution was then transferred to a hydrothermal reactor for a two-stage temperature-controlled crystallization process: the first stage crystallization temperature was set at 50°C for 14 hours; the second stage crystallization temperature was controlled at 100°C for 18 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution. Waste Z-5 molecular sieve catalyst was mixed with NaCO3 at a mass ratio of 1:1 and calcined at 700℃ for 90 min. The calcined product was then dissolved with a 20% monobasic acid and filtered to obtain an aluminum-rich liquid and an aluminum-dissolving filter residue. The aluminum-dissolving filter residue was mixed with NaOH and H2O at a mass ratio of 50:50:200 and filtered to obtain a silicon-rich liquid. The silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor. Seed crystals of a certain mass ratio were added to the gel-like mother liquor, and then aging and crystallization treatments were carried out sequentially. The aging temperature was 60℃ for 12 h, and the crystallization temperature was 80℃ for 18 h. After drying, 13X molecular sieve was obtained.

[0035] Example 3: 0.17g of silicon powder was dissolved in 6g of deionized water and pretreated in a sealed reactor at 25°C and 200rpm for 1 hour to obtain an aqueous dispersion of the silicon source. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35°C and 200rpm for 1 hour to prepare an aqueous dispersion of the aluminum source. The aluminum source solution was slowly added to the silicon source solution and stirred at 100°C for 24 hours to obtain a gel solution. 0.9g of sodium hydroxide was dissolved in 6g of deionized water to prepare a dispersion, which was then slowly added to gel solution E, adjusting the pH to 12.5. The prepared gel was then poured into a hydrothermal reactor for two-stage crystallization: first, crystallization was carried out at 60°C for 24 hours, and then the temperature was increased to 120°C for 48 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution. Waste FCC catalyst was mixed with NaCO3 at a mass ratio of 1:0.5 and calcined at 550℃ for 120 min. The calcined product was then dissolved with a 10% monobasic acid and filtered to obtain an aluminum-rich liquid and an aluminum-dissolving filter residue. The aluminum-dissolving filter residue was mixed with NaOH and H2O at a mass ratio of 2:40:50 and filtered to obtain a silicon-rich liquid. The silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor. Seed crystals of a certain mass ratio were added to the gel-like mother liquor, and then aging and crystallization treatments were carried out sequentially. The aging temperature was 20℃ for 24 h, and the crystallization temperature was 60℃ for 36 h. After drying, 13X molecular sieve was obtained.

[0036] Example 4: 14.65g of tetraethyl orthosilicate and 36g of deionized water were mixed and pretreated in a sealed reactor at 25°C and 800rpm for 1 hour to obtain a silicon source dispersed phase aqueous solution. 12g of aluminum nitrate was dissolved in 18.0g of deionized water and stirred at 35°C and 800rpm for 1 hour to obtain an aluminum source dispersed phase aqueous solution. The aluminum source solution was gradually added dropwise to the silicon source solution and stirred at 20°C for 0.1 hours to prepare a gel solution. 0.56g of sodium hydroxide was dissolved in 6g of deionized water as a dispersion and slowly poured into the gel solution, maintaining a pH of 8.5. The prepared gel was introduced into a hydrothermal reactor to perform a segmented crystallization reaction: first, the crystallization temperature was set at 20°C and maintained for 4 hours; then, it was increased to 80°C and maintained for 6 hours. Deionized water was added as needed during the crystallization process to obtain a seed crystal solution. Waste molecular sieve adsorbent was mixed with NaCO3 at a mass ratio of 1:1:5 and calcined at 800℃ for 60 min. The calcined product was then dissolved with a 35% monobasic acid and filtered to obtain an aluminum-rich liquid and an aluminum-dissolving filter residue. The aluminum-dissolving filter residue was mixed with NaOH and H2O at a mass ratio of 100:60:400 and filtered to obtain a silicon-rich liquid. The silicon-rich liquid and the aluminum-rich liquid were mixed to obtain a gel-like mother liquor. Seed crystals of a certain mass ratio were added to the gel-like mother liquor, and then aging and crystallization treatments were carried out sequentially. The aging temperature was 100℃ and the time was 0.1 h. The crystallization temperature was 105℃ and the time was 0.1 h. After drying, 13X molecular sieve was obtained.

[0037] Test method:

[0038] Molar ratio: X-ray fluorescence spectroscopy (XRF) analysis

[0039] Silicon-to-aluminum ratio: X-ray fluorescence spectroscopy (XRF) analysis

[0040] Kong Rong: BET Test Method

[0041] Specific surface area: BET test method

[0042] Adsorption performance: Fixed-bed adsorption experiment: An alkane-alkene mixture is passed through a fixed bed containing an adsorbent, and the concentration change of the alkane-alkene mixture passing through the bed is monitored to determine the adsorption performance of the adsorbent for a specific alkane-alkene mixture.

[0043]

[0044] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing alkane adsorbents from spent catalysts, characterized in that: 13X molecular sieve was subjected to a hydrothermal reaction with a certain silicon source solution. The molecular sieve after the hydrothermal reaction was calcined. The calcined molecular sieve was then immersed in a zinc source solution, filtered, washed, and dried. The molecular sieve was then reacted with a reducing agent solution, wherein the reducing agent was a sodium borohydride (NaBH4) solution. The reacted molecular sieve was filtered, washed, and dried again. The molecular sieve was then subjected to a final calcination treatment. The calcined molecular sieve was then vacuum dried at room temperature to obtain an alkene adsorbent. The preparation method of the 13X molecular sieve is as follows: (1) a silicon source and water are mixed evenly to obtain a silicon-containing material, and an aluminum source and water are mixed evenly to obtain an aluminum-containing material; (2) the aluminum-containing material is slowly added dropwise to the silicon-containing material, and the mixture is stirred for a period of time to obtain a mixture gel. The pH value of the mixture gel is adjusted to 8.5-12.5, and then a two-stage hydrothermal crystallization treatment is performed to obtain a crystallization product; (3) the molecular sieve-containing material is subjected to aluminum dissolution and silicon dissolution treatment to obtain a silicon-rich liquid and an aluminum-rich liquid. The two are mixed to obtain a gel-like mother liquor; (4) the crystallization product of step (2) is added to the gel-like mother liquor of step (3) for aging treatment, and then hydrothermal crystallization treatment is performed. The reaction product is filtered, washed, and then dried to obtain the 13X molecular sieve. The molecular sieve-containing material mentioned in step (3) is selected from one or more of the following: waste MTO catalyst, waste molecular sieve adsorbent, waste FCC catalyst, and waste VOC adsorbent; 13X molecular sieve has the following properties: a silica-to-alumina ratio of 2.2–2.9, and a pore volume of 0.3 cm³. 3 / g~0.5 cm 3 / g, specific surface area 700m² 2 / g~950 m 2 / g.

2. The method according to claim 1, characterized in that: The silicon source mentioned in step (1) is selected from one or more of silica sol, tetraethyl orthosilicate, coarse-porous silica gel, silica powder, fly ash, and silica. The aluminum source is selected from one or more of sodium aluminate, boehmite, aluminum sulfate, and aluminum nitrate.

3. The method according to claim 1, characterized in that: The stirring conditions described in step (2) are stirred at 20~100℃ for 0.1~24h to obtain a mixture gel.

4. The method according to claim 1, characterized in that: The molar ratios of the components in the crystallized product obtained in step (2) are SiO2 / Al2O3 = (0.1~2.5):1, Na2O / SiO2 = (0.1~4.0):1, and H2O / SiO2 = (1.0~40.0):

1.

5. The method according to claim 1, characterized in that: The aluminum and silicon dissolution processes described in step (3) are as follows: The molecular sieve material is ground to a sample below 200 mesh, mixed with NaCO3 at a mass ratio of 1:0.5~1:5, and calcined at 550-800℃ for 60-120 min. Then, the calcined product is dissolved and filtered with a monobasic acid with a mass fraction of 10%-35% to obtain an aluminum-rich liquid. The residue is mixed with NaOH:H2O at a mass ratio of 2-100:40-60:50-400, stirred and mixed evenly, and filtered to obtain a silicon-rich liquid. Finally, the silicon-rich liquid and the aluminum-rich liquid are mixed to obtain a gel-like mother liquor. The molar ratio of each component in the gel-like mother liquor is: SiO2 / Al2O3=0.5~6.0:1, Na2O / SiO2=0.5~6.0:1, H2O / SiO2=10~100:

1.

6. The method according to claim 1, characterized in that: The amount of crystallized product added in step (4) is 5wt%-20wt% of the gel-like mother liquor; The aging conditions described in step (4) are: aging temperature of 20~100℃, aging time of 0.1~24h, and the aging process is carried out under stirring conditions.

7. The method according to claim 1, characterized in that: The hydrothermal crystallization conditions described in step (4) are: crystallization temperature of 60-105℃ and crystallization time of 0.1-36h.

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