Process for preparing high silica y-zeolites using waste silica sources

Abstract

Disclosed is a process for preparing a high silica Y-zeolite by utilizing a waste silica source. The method comprises the following steps: preparing a dilute nucleating agent, and preparing a thick nucleating agent by mixing sodium silicate, sodium aluminate, deionized water and sodium hydroxide. Furthermore, an aluminosilicate gel is prepared by mixing the dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water and the thick nucleating agent, and then the aluminosilicate gel is crystallized, filtered and washed to obtain a Y-zeolite filter cake. The Y-zeolite is ammonium exchanged, dried and calcined to obtain a high silica Y-zeolite.

Description

Technical Field

[0001] The present disclosure generally relates to high silica Y-zeolite and methods for preparing the same. In particular, the present disclosure relates to methods for preparing high silica Y-zeolite using spent silica sources. Background Art

[0002] Synthetic Y-zeolite has been used as a key active component of fluid catalytic cracking catalysts for more than 50 years. In the synthesis method of Y-zeolite / 13X zeolite, silica, alumina and sodium hydroxide sources are used. In the synthesis step, alumina is almost completely consumed, while most of the silica is still unused. This unconsumed silica enters the mother liquor. This silica-rich mother liquor can be used as a silica source for synthesizing high-silicon Y-zeolite. This will help solve environmental pollution problems and reduce the synthesis cost of Y-zeolite.

[0003] US3898319A discloses a method for preparing zeolite Y, wherein the method utilizes solid reactive silica derived from the waste liquor of a previous zeolite synthesis reaction. The synthesis is accomplished by supplementing the waste liquor with sodium silicate and chemically precipitating the silica with carbon dioxide under special conditions.

[0004] US 4164551A discloses a process for preparing Y-zeolite, wherein a zeolite crystallization mother liquor containing excess silicate is combined with an acidic aluminum salt to obtain a precipitated silica-alumina hydrogel.

[0005] US20040053773A1 discloses a method for eliminating unwanted excess silicon dioxide and sodium salts from the mother liquor obtained after molecular sieve separation, and paves the way for complete recovery of the mother liquor. Sodium hydroxide is neutralized using a dilute mineral acid until the final pH value of the acid mother liquor is in the range of 9 to 12.5 at a low temperature in the range of 5 to 25°C. This results in the enrichment of silicon dioxide and the reduction of the amount of unwanted sodium salts and sodium salts in the mother liquor.

[0006] The amount of silica and sodium salt present in the spent mother liquor is high, which needs to be neutralized before treatment. If it is discarded without treatment, it may cause environmental pollution. Therefore, it is necessary to recover and reuse the unconverted silica and sodium salt in the spent zeolite mother liquor. Therefore, the present invention provides a solution to this problem by utilizing the spent zeolite mother liquor as a source of silica for synthesizing high-siliceous Y-zeolite. Summary of the invention

[0007] The present disclosure relates to high silica Y-zeolite. The present invention particularly relates to a method for preparing high silica Y-zeolite by utilizing spent zeolite mother liquor, wherein the zeolite mother liquor may be a mother liquor from Y zeolite synthesis or a mother liquor from 13X zeolite synthesis or a mother liquor from zeolite 4A synthesis. The method comprises the step of preparing a dilute nucleating agent by aging the zeolite mother liquor at a temperature in the range of 40-50°C for 24-36 hours. A dense nucleating agent is then prepared by mixing sodium silicate, sodium aluminate, sodium hydroxide and deionized water and aging at a temperature in the range of 35-45°C for 20-24 hours.

[0008] Then, an aluminosilicate gel is prepared by mixing a dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water, and a dense nucleating agent, and the aluminosilicate gel is crystallized at a temperature in the range of 100-110° C. for 20-24 hours, filtered and washed to obtain a Y-zeolite filter cake. Subsequently, the Y-zeolite filter cake is dried at 100-110° C. for 5 hours, and then ammonium ion exchange is performed, and then calcined at 500-550° C. for 3 hours to obtain a high silica Y-zeolite. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like numerals represent like parts throughout the several views, wherein:

[0010] Figure 1 A process flow diagram for preparing high silica Y-zeolite using a spent silica source is illustrated. DETAILED DESCRIPTION

[0011] The present disclosure solves the shortcomings of the prior art and provides a method for preparing high silica Y-zeolite using a waste silica source. In some embodiments, the method provides for the recovery and reuse of waste silica sources, reducing environmental pollution by utilizing waste silica as a silica source for synthesizing high silica Y-zeolite.

[0012] For the purpose of promoting understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the accompanying drawings, and specific language will be used to describe the embodiments. However, it should be understood that the scope of the present disclosure is not intended to be limited thereby, and such changes and further modifications in the illustrated system and such further applications of the principles of the present disclosure illustrated therein are considered to be conventionally expected by those skilled in the art to which the present disclosure relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those of ordinary skill in the art to which the present disclosure belongs. The systems, methods and examples provided herein are illustrative only and are not intended to be limiting.

[0013] Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and / or materials cited in these publications.

[0014] It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context dictates otherwise. Thus, for example, reference to "a compound" includes a plurality of such compounds, reference to "the step" includes reference to one or more steps and equivalents thereof known to those skilled in the art, and so forth.

[0015] As used herein, the term "some" is defined as "none, or one, or more than one, or all." Thus, the terms "none," "one," "more than one," "more than one but not all," or "all" are within the definition of "some." The term "some embodiments" may mean no embodiments, or one embodiment, multiple embodiments, or all embodiments. Thus, the term "some embodiments" is defined to mean "no embodiments, or one embodiment, or more than one embodiments, or all embodiments."

[0016] The terms and structures used herein are used to describe, teach, and illustrate some embodiments and specific features and elements thereof, and are not intended to restrict, define, or reduce the spirit and scope of the claims or their equivalents.

[0017] More specifically, any term used herein, such as, but not limited to, "including," "comprising," "having," "consisting of," and grammatical variations thereof, is inclusive or open-ended and does not exclude additional, uncited elements or method steps. The specification will be understood to also include embodiments having the transition phrases "consisting of" or "consisting essentially of" in place of the transition phrase "comprising." The transition phrase "consisting of" excludes any element, step, or ingredient not specified in the claim, except for impurities associated therewith. The transition phrase "consisting essentially of" limits the scope of the claim to the disclosed specified materials or steps claimed "and those that do not materially affect the basic and novel characteristic(s)."

[0018] Regardless of whether a particular feature or element is limited to only one use, it is still referred to as "one or more features" or "one or more elements" or "at least one feature" or "at least one element" in either manner. In addition, the use of the term "one or more" or "at least one" feature or element does not exclude the absence of any such feature or element, unless otherwise specified by limiting language such as "one or more is required." or "one or more elements are required."

[0019] As used herein, the term "about" is used to indicate a degree of variation or tolerance in a numerical or quantitative value. It means that the disclosed value is not intended to be strictly limited and may vary by plus or minus 5% without departing from the scope of the invention.

[0020] Unless otherwise defined, all terms used herein, especially any technical and / or scientific terms, may be considered to have the same meaning as commonly understood by one of ordinary skill in the art.

[0021] Reference is made herein to some "embodiments". It should be understood that an embodiment is an example of a possible implementation of any feature and / or element presented in the appended claims. Some embodiments have been described for the purpose of illustrating one or more potential ways in which a particular feature and / or element of the appended claims satisfies the requirements of uniqueness, usefulness, and non-obviousness.

[0022] The use of phrases and / or terms such as, but not limited to, "a first embodiment", "a further embodiment", "an alternative embodiment", "an embodiment", "an embodiment", "an embodiment", "some embodiments", "other embodiments", "a further embodiment", "a further embodiment", "an additional embodiment" or variations thereof do not necessarily refer to the same embodiment. Unless otherwise specified, one or more particular features and / or elements described in conjunction with one or more embodiments may be found in one embodiment, or may be found in more than one embodiment, or may be found in all embodiments, or may not be found in any embodiment. Although one or more features and / or elements may be described herein only in the context of a single embodiment, or alternatively in the context of more than one embodiment, or further alternatively in the context of all embodiments, the features and / or elements may alternatively be provided individually or in any appropriate combination, or may not be provided at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be implemented as present together in the context of a single embodiment.

[0023] As used herein, the term "waste" refers to material that is undesirable or unusable.

[0024] As used herein, the terms "means" and "method" are used interchangeably.

[0025] The present disclosure discloses a method for preparing high silica Y-zeolite by utilizing a spent silica source.

[0026] In some embodiments, the method includes preparing a dilute nucleating agent, preparing a dense nucleating agent; preparing an aluminosilicate gel by mixing the dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water and the dense nucleating agent; and crystallizing the aluminosilicate gel to obtain a high silica Y-zeolite.

[0027] The process of the present disclosure provides a high silica Y-zeolite that can be prepared by utilizing a spent silica source.

[0028] The present disclosure discloses a method for preparing high silica Y-zeolite by utilizing a spent silica source, wherein the method comprises the following steps: a) preparing a dilute nucleating agent by aging the spent silica source at a temperature in the range of 40-50°C for 24-36 hours; b) preparing a dense nucleating agent by mixing sodium silicate, sodium aluminate, sodium hydroxide and deionized water, and then aging at a temperature in the range of 35-45°C for 20-24 hours; c) preparing an aluminosilicate gel by mixing the dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water and the dense nucleating agent; d) crystallizing the aluminosilicate gel obtained from step c) at a temperature in the range of 100-110°C for 20-24 hours, filtering and washing to obtain a Y-zeolite filter cake, drying the Y-zeolite filter cake at 100°C-110°C for 5 hours, removing sodium by ammonium exchange, and then obtaining a high silica Y-zeolite by calcining at 500°C-550°C for 3 hours.

[0029] In an embodiment of the present invention, the method is provided wherein the spent silica source is aged at 40-50°C for 24-36 hours.

[0030] In another embodiment, wherein the spent silica source is aged at 40-50°C for 24-36 hours.

[0031] In a preferred embodiment, the spent silica source is aged at 42-48°C for 25-35 hours.

[0032] In another embodiment of the present invention, the process is provided wherein the spent silica source is selected from the group consisting of Y-zeolite mother liquor, 13X zeolite mother liquor and zeolite 4A mother liquor.

[0033] In a preferred embodiment of the present invention, the process is provided wherein the spent silica source is selected from the group consisting of Y zeolite mother liquor and 13X zeolite mother liquor.

[0034] In another embodiment of the present invention, the method is provided wherein the spent silica source consists of 1-10 SiO2 / SO4.

[0035] In a preferred embodiment of the present invention, the method is provided wherein the spent silica source has a SiO2 / SO4 ratio of 3-6.

[0036] In yet another embodiment of the present invention, the method is provided wherein the spent silica source consists of SiO2 / Na2O in the range of 1-5.

[0037] In a preferred embodiment of the present invention, the method is provided wherein the spent silica source consists of 1-3 SiO2 / Na2O.

[0038] In yet another embodiment of the present invention, there is provided the method, wherein the condensed nucleating agent is prepared by mixing sodium aluminate and sodium hydroxide in deionized water to obtain a first solution, mixing sodium silicate in deionized water to obtain a second solution, mixing the first solution and the second solution and aging the obtained solution at 35-45° C. for 20-24 hours.

[0039] In still another embodiment of the present invention, there is provided the process, wherein the aluminosilicate gel is prepared by mixing a dilute nucleating agent, sodium, adding aluminum sulfate solution, deionized water and a dense nucleating agent.

[0040] In another embodiment of the present invention, the method is provided, wherein the composition of the aluminosilicate gel is SiO2:Na2O:Al2O3:SO4:H2O in a ratio of 7-20:2-10:1:0-5:200-400.

[0041] In a preferred embodiment of the present invention, the method is provided wherein the composition of the aluminosilicate gel is SiO2:Na2O:Al2O3:SO4:H2O in a ratio of 10-15:5-10:1:0-2:200-300.

[0042] In yet another embodiment of the present invention, crystallization of aluminosilicate gel is carried out at a temperature in the range of 100-110°C for 20-24 hours, filtered and washed to obtain a Y-zeolite filter cake, the Y-zeolite cake is dried at 100-110°C for 5 hours, ammonium exchanged to remove sodium, and then calcined at 500-550°C for 3 hours to obtain high silica Y-zeolite.

[0043] In yet another embodiment of the present invention, there is provided the method, wherein the ammonium ion exchange is performed using an ammonium salt selected from ammonium nitrate, ammonium sulfate, ammonium chloride or a combination thereof.

[0044] In an embodiment of the present invention, the process is provided wherein the Y-zeolite has a molecular weight of 900-950 m 2 / g of surface area.

[0045] In yet another embodiment of the present invention, the process is provided, wherein the high silica Y-zeolite has a unit cell size of 24.55-24.65 angstroms.

[0046] In yet another embodiment of the present invention, the process is provided wherein the high silica Y-zeolite has a SiO2 / Al2O3 framework of 5-7.

[0047] In an exemplary and non-limiting embodiment, Figure 1 , a method for preparing high silica Y-zeolite by utilizing a spent silica source is described. A dilute nucleating agent is prepared by aging the spent silica source in a container (100) at a temperature in the range of 40-50°C for 24-36 hours. A dense nucleating agent is prepared by mixing sodium silicate, sodium aluminate, sodium hydroxide, and deionized water in a container (200) and aging at a temperature in the range of 35-45°C for 20-24 hours. An aluminosilicate gel is prepared by mixing the dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water, and the dense nucleating agent in a container (300) using an agitator (310). The aluminosilicate gel is crystallized in an autoclave (400) at a temperature in the range of 100-110°C for 20-24 hours, filtered and washed in a centrifugal filtration unit (500) to obtain a Y-zeolite filter cake, the Y-zeolite filter cake is dried in an air oven (600) at 100-110°C for 5 hours, ammonium exchanged in a container (700) to remove sodium, dried in an air oven (800) at 100-110°C, and then calcined in a muffle furnace (900) at 500-550°C for 3 hours to obtain a high silica Y-zeolite.

[0048] Example:

[0049] The present disclosure is further illustrated by reference to the following examples, which are for illustrative purposes only and do not limit the scope of the present disclosure in any way. These examples are not intended to include all aspects of the subject matter disclosed herein, but rather to illustrate representative features, methods, compositions and results. These examples are not intended to exclude equivalents and variants of the present disclosure, which are apparent to those skilled in the art.

[0050] Example 1: Preparation of a thickening nucleating agent

[0051] 12 g of sodium aluminate was dissolved in 70 g of deionized water under stirring. 25.6 g of sodium hydroxide was dissolved in the sodium aluminate solution, named solution 1. 112 g of sodium silicate was dispersed in 75 g of deionized water under stirring, named solution 2. Solution 1 was added to solution 2 under vigorous stirring. After stirring, the thickened nucleating agent was aged at 35°C for 24 hours.

[0052] Example 2: Preparation of dilute nucleating agent

[0053] Preparation of dilute nucleating agent from spent silica source, wherein the spent silica source used was Y-zeolite mother liquor / 13X zeolite mother liquor. 875 g of Y-zeolite mother liquor was aged at 45° C. for 30 hours to obtain the dilute nucleating agent.

[0054] Example 3: Preparation of high silica Y-zeolite

[0055] 875 g of dilute nucleating agent was added to 357 g of sodium silicate and diluted with 100 g of deionized water. 269 g of thick nucleating agent was added to the solution and the solution was stirred vigorously. 257 g of aluminum sulfate was dissolved in 500 g of deionized water under stirring until a clear solution was prepared. The aluminum sulfate solution was added dropwise to the solution prepared above under stirring. The solution was kept under vigorous stirring for 30 minutes. The prepared aluminosilicate was crystallized at 105 ° C for 24 hours. After the crystallization was completed, the zeolite was filtered and washed. The Y-zeolite filter cake obtained was dried at 100-110 ° C for 5 hours. After drying, the obtained Y zeolite was exchanged for ammonium ions 4 times using a 5 wt % ammonium sulfate solution. The sample was filtered, washed and dried at 100-110 ° C for 5 hours, and the obtained Y zeolite was calcined at 500 ° C for 3 hours. The obtained Y zeolite was named HSY-zeolite. The steaming of the HSY-zeolite sample was carried out at 810 ° C for 5 hours. The steamed powder was named HSY-zeolite-St.

[0056] Comparative Example 1: Preparation of HY-zeolite-St.

[0057] 87.5 g of aluminum sulfate was dissolved in 500 g of deionized water under stirring to prepare a transparent aluminum sulfate solution. 73.5 g of sodium aluminate was dissolved in 300 g of deionized water.

[0058] 741 g of sodium silicate was dissolved in 100 g of deionized water under stirring to prepare a silica solution. First, the sodium aluminate solution was added dropwise to the silica solution, and then an aluminum sulfate solution was added to the solution to prepare an aluminosilicate gel.

[0059] 269 ​​gm of the thick nucleating agent prepared in Example 1 was added to the aluminosilicate gel. The solution was kept under vigorous stirring for 30 minutes. The prepared aluminosilicate was crystallized at 105°C for 24 hours. After the crystallization was completed, the zeolite was filtered and washed. The Y-zeolite filter cake obtained was dried at 100-110°C for 5 hours. After drying, the obtained Y zeolite was ammonium ion exchanged four times using 5 wt% ammonium sulfate solution. The sample was filtered, washed and dried at 100-110°C for 5 hours, and the obtained Y zeolite was calcined at 500°C for 3 hours. The obtained Y zeolite was named HY-zeolite. Steaming of the HY-zeolite sample was carried out at 810°C for 5 hours. The steamed powder was named HY-zeolite-St.

[0060] Comparative Example 2: Preparation of HCY-zeolite-St

[0061] Commercial NaY zeolite was ion exchanged four times using 5 wt% ammonium sulfate solution. The sample was filtered, washed and dried at 100-110°C for 5 hours, the dried zeolite obtained was calcined at 500°C, and the Y zeolite obtained was named HCY-zeolite. The steaming of the HCY-zeolite sample was carried out at 810°C for 5 hours. The steamed powder sample was named HCY-zeolite-St.

[0062] Table 1: Structural characteristics of Y-zeolite samples

[0063]

[0064] Embodiment 4:

[0065] The cracking performance of steamed Y-zeolite was tested in a fixed bed reactor. The amount of catalyst used was 5 g, the decane feed rate was about 2 g / min, the injection time was 30 seconds, the reaction temperature was maintained at about 500°C, and the reaction pressure was 1 kg / cm 2 g, the regeneration temperature was maintained at about 700° C. The catalytic cracking performance of steamed Y-zeolites: HY-zeolite-St, HCY-zeolite-St and HSY-zeolite-St was evaluated using n-decane as feed. Table 2 lists the conversion and product yields obtained using different Y-zeolites in various examples.

[0066] Table 2: Evaluation of catalytic cracking performance of Y-zeolite in a fixed bed reactor

[0067]

[0068] Advantages of the present invention:

[0069] The advantages of the present invention over the prior art are that the Y-zeolite prepared using a waste silica source increases the ratio of silica to alumina in the Y-zeolite, and thus improves the LPG selectivity and the light olefin selectivity. It reduces environmental pollution and reduces the preparation cost of high silica Y-zeolite.

Claims

1. A method for preparing high silica Y-zeolite using a waste silica source, wherein the method comprises the following steps: a. preparing a dilute nucleating agent by aging a spent silica source at a temperature in the range of 40-50 ° C for 24-36 hours; b. A thick nucleating agent is prepared by mixing sodium silicate, sodium aluminate, sodium hydroxide and deionized water, and then aging at a temperature in the range of 35-45 ° C for 20-24 hours; c. preparing an aluminosilicate gel by mixing a dilute nucleating agent with sodium silicate, aluminum sulfate, deionized water and a thick nucleating agent; and d. Crystallize the aluminosilicate gel obtained from step c) at a temperature in the range of 100-110°C for 20-24 hours, filter and wash to obtain a Y-zeolite filter cake, dry the Y-zeolite filter cake at 100-110°C for 5 hours, ammonium exchange to remove sodium, and then calcine at 500-550°C for 3 hours to obtain a high silica Y-zeolite.

2. The method of claim 1, wherein the spent silica source is aged at 42-48°C for 25-35 hours.

3. The method of claims 1-2, wherein the spent silica source is selected from the group consisting of Y-zeolite mother liquor, 13X zeolite mother liquor and zeolite 4A mother liquor.

4. The method of claim 3, wherein the spent silica source is selected from the group consisting of Y-zeolite mother liquor and 13X zeolite mother liquor.

5. The method of claims 1-3, wherein the spent silica source consists of a SiO2 / SO4 molar ratio of 1-10.

6. The method of claim 5, wherein the spent silica source consists of a SiO2 / SO4 molar ratio of 3-6.

7. The method of claims 1-3, wherein the spent silica source consists of a SiO2 / Na2O molar ratio of 1-5.

8. The method of claim 7, wherein the SiO2 / Na2O of the spent silica source is 1-3.

9. The method according to claim 1, wherein the molar composition of the aluminosilicate gel is SiO2:Na2O:Al2O3:SO4:H2O in a ratio of 7-20:2-10:1:0-5:200-400.

10. The method according to claim 9, wherein the molar composition of the aluminosilicate gel is SiO2:Na2O:Al2O3:SO4:H2O in a ratio of 10-15:5-10:1:0-2:200-300.

11. The method according to claim 1, wherein the high silica Y-zeolite has a silica content of 900-950 m 2 / g of surface area.

12. The method of claim 1, wherein the high silica Y-zeolite has a unit cell size of 24.55-24.65 angstroms.

13. The method of claim 1, wherein the high silica Y-zeolite has a SiO2 / Al2O3 framework of 5-7.

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