Method for preparing mordenite molecular sieve from waste Y molecular sieve

Abstract

The invention discloses a method for preparing a mordenite molecular sieve from a waste Y molecular sieve, and belongs to the technical field of molecular sieve preparation. According to the method, the waste Y molecular sieve is adopted as a direct silicon-aluminum source, a proper template agent and a proper alkali source are added, the pH value of a reaction solution is strictly regulated and controlled, and reaction conditions are controlled, so that the waste Y molecular sieve is successfully converted to prepare the mordenite molecular sieve with a hierarchical pore structure, resource utilization of the waste Y molecular sieve is realized, the production cost is reduced, and the environmental pollution is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve catalyst preparation, and specifically relates to a method for preparing mordenite molecular sieve by using waste Y molecular sieve as raw material through a specific conversion process. Background Art

[0002] Y molecular sieve and mordenite molecular sieve are two types of molecular sieves widely used in the oil refining and petrochemical industries. Y molecular sieve is an octahedral zeolite cage surrounded by a β cage and a hexagonal column cage. The basic structure of the skeleton is composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron. It has a large supercage cavity and a three-dimensional twelve-ring pore system. It is used in hydrogenation catalysis, oil cracking, FCC catalyst, high-efficiency adsorption separation, and environmental protection. It is also widely used. However, as the use time increases, Y molecular sieve may be deactivated due to carbon deposition, poisoning, etc., resulting in a large amount of waste Y molecular sieve.

[0003] Mordenite has good thermal and hydrothermal stability, and its unique pores give it excellent catalytic and adsorption properties. Mordenite is mainly used in the field of heterogeneous catalysis, such as toluene disproportionation, catalytic cracking, hydrocracking, superposition deolefination, alcohol amination, aromatic alkylation, etc. It is also often used as an adsorbent for the separation of gas or liquid mixtures. Therefore, converting discarded Y molecular sieves into mordenite not only solves the problem of handling industrial waste catalysts, but also realizes the reuse of resources, which has important economic value and social significance.

[0004] CN104276586B discloses a method for preparing mordenite, but the synthesis is too heavy and requires additional natural silica-alumina minerals, and the natural silica-alumina minerals need to be activated. CN109485064B discloses a method for preparing mordenite from waste MTP catalysts and the application of waste MTP catalysts, using waste MTP molecular sieve catalysts (SiO 2 / Al 2 O 3=4-14) as raw materials, and the carbon deposits in the catalyst are removed in advance by calcination for the preparation of mordenite. The MTP catalyst used in the MTP process is mainly the active component of ZSM-5 molecular sieve containing silicon and aluminum species. ZSM-5 molecular sieve is composed of straight channels composed of ten-membered rings and spiral channels composed of eight-membered rings. Y zeolite molecular sieve (also known as FAU type zeolite) is a zeolite with a three-dimensional twelve-membered ring channel structure, which is widely used in the field of petrochemical industry, such as being used as a catalyst and catalyst carrier in cracking, isomerization, hydrogenation and other reactions. The amount of Y molecular sieve catalyst used in industry is huge, and a large amount of waste Y molecular sieve catalyst will be generated every year. The treatment and reuse of waste Y type zeolite molecular sieve is an important environmental issue. At present, there is no public report on the method of converting waste Y molecular sieve catalyst into mordenite. Therefore, the development of a method for directly preparing mordenite molecular sieve using waste Y molecular sieve as raw material will not only help to realize the resource utilization of waste, but also reduce production costs and reduce environmental pollution. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing mordenite molecular sieve from waste Y molecular sieve, which uses waste Y molecular sieve as raw material and prepares mordenite molecular sieve with a multi-level pore structure through a specific conversion process.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: A method for preparing mordenite molecular sieve from waste Y molecular sieve, comprising the following steps: a) pre-treating the waste Y molecular sieve; b) mixing the pretreated waste Y molecular sieve with an alkali source and deionized water, and stirring; then adding a template, and stirring at a specific temperature to obtain a gel solution; c) placing the gel solution into a sealed container for hydrothermal crystallization to obtain Na-type mordenite molecular sieve; d) washing, drying, ion exchanging and calcining the Na-type mordenite molecular sieve to obtain a final product, the mordenite molecular sieve product.

[0007] Preferably, the method for pretreating the waste Y molecular sieve in step a) is: grinding the waste Y molecular sieve to make the crystal particle size less than 10 μm, and the silicon-aluminum ratio (SiO 2 / Al 2 O 3 ) is 5~100.

[0008] Preferably, the template agent in step (b) is one of piperazine, tetraethylammonium hydroxide, glycerol, ethylene glycol and polyethylene glycol, or a combination thereof.

[0009] Preferably, the alkali source in step (b) is sodium hydroxide or potassium hydroxide.

[0010] Preferably, in step (b), the pH of the gel solution is 13-14, and the reaction temperature is 40-60° C. and stirred for 1-4 h.

[0011] Preferably, in step (b), the molar ratio of template agent / waste Y molecular sieve is 1:2-20, and the molar ratio of waste Y molecular sieve / deionized water is 1:20-40.

[0012] Preferably, the hydrothermal crystallization reaction temperature is 140-220° C., and the crystallization time is 12-72 h.

[0013] Preferably, in step d), the calcination temperature is 500-550° C. and the calcination time is 3-6 h.

[0014] Beneficial effects of the present invention: (1) The present invention realizes the reuse of waste Y molecular sieves without adding new silicon and aluminum sources, thereby reducing the preparation cost of mordenite molecular sieves and the treatment cost of waste Y molecular sieves, realizing the resource utilization of waste and reducing environmental pollution.

[0015] (2) The preparation method of the present invention is simple, low-cost, and has high conversion efficiency. The prepared mordenite molecular sieve has good catalytic performance, realizing the conversion of low-value waste catalysts to high-value-added mordenite molecular sieves, with significant social and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD pattern of the mordenite molecular sieve prepared in Example 1; Figure 2 This is the SEM image of the mordenite molecular sieve prepared in Example 1. DETAILED DESCRIPTION

[0017] The following examples are only intended to illustrate the preferred technical solutions of the present invention and are not intended to limit the scope of the present invention in any form. For professionals in this field, the present invention has a high degree of flexibility and variability, allowing for a variety of adjustments and changes. The following will further illustrate the relevant contents of the present invention through specific implementation cases.

[0018] Example 1 A method for preparing mordenite molecular sieve from waste Y molecular sieve, comprising the following steps: a) grinding the waste Y molecular sieve to make the crystal particle size less than 10 μm, wherein the waste Y molecular sieve has a silicon-aluminum ratio (SiO 2 / Al 2 O 3 ) is 5; b) Weigh 0.40 g of NaOH and H 2 O 12 g, stirred to dissolve; added 2 g of ground discarded Y molecular sieve and stirred to mix, then added 3.56 g of template agent tetraethylammonium hydroxide, aged at 60 ° C for 4 h and adjusted the pH of the mixture to about 13; c) transferring the gel solution into an autoclave and crystallizing at 160 °C for 48 h to obtain Na-type mordenite; d) The product is washed, dried, calcined at 550°C for 5 h and subjected to ammonium ion exchange (80°C-5 h) to obtain H-type mordenite.

[0019] Example 2 A method for preparing mordenite molecular sieve from waste Y molecular sieve, comprising the following steps: a) grinding the waste Y molecular sieve to make the crystal particle size less than 10 μm, wherein the waste Y molecular sieve has a silicon-aluminum ratio (SiO 2 / Al 2 O 3 ) is 40; b) Weigh 2 g of ground waste Y molecular sieve, 0.50 g of NaOH and H 2 O 13 g, stirred for 30 min; then added 2 g ethylene glycol and 1.56 g tetraethylammonium hydroxide; sodium hydroxide was used to adjust the pH of the gel system to about 14, and a gel solution was obtained; c) the gel solution was placed in a high pressure reactor and crystallized at 180°C for 36 h to obtain Na-type mordenite; d) washing, drying, calcining (550°C-5 h) and exchanging ammonium ions (80°C-5 h) the above product to obtain H-type mordenite.

[0020] Example 3 A method for preparing mordenite molecular sieve from waste Y molecular sieve, comprising the following steps: a) grinding the waste Y molecular sieve to make the crystal particle size less than 10 μm, wherein the waste Y molecular sieve has a silicon-aluminum ratio (SiO 2 / Al 2 O 3 ) is 100; b) Weigh 2.42 g of ground waste Y molecular sieve and add it to an alkaline aqueous solution consisting of 0.24 g KOH and 12 g water, and stir vigorously for 30 min; then add 2.55 g tetraethylammonium hydroxide and 1.25 g polyethylene glycol, stir at 60 °C for 4 h, and adjust the pH of the mixture solution to about 13; c) The reaction mixture was then transferred to a reactor and crystallized at 210 °C for 72 h; d) The obtained solid is filtered, washed to a pH value between 7 and 8, and dried overnight; the obtained powder is calcined at 550°C for 5 h, and ammonium ions are exchanged to obtain H-type mordenite molecular sieve.

[0021] After testing, the sample prepared by the method of the present invention has a crystal phase consistent with the mordenite molecular sieve obtained by hydrothermal synthesis in the prior art (such as Figure 1 as shown).

[0022] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A method for preparing mordenite molecular sieve from waste Y molecular sieve, characterized in that: It includes the following steps: a) pre-treating the waste Y molecular sieve; b) mixing the pretreated waste Y molecular sieve with an alkali source and deionized water, and stirring; then adding a template, and stirring at a specific temperature to obtain a gel solution; c) placing the gel solution into a sealed container for hydrothermal crystallization to obtain Na-type mordenite molecular sieve; d) washing, drying, ion exchanging and calcining the Na-type mordenite molecular sieve to obtain a final product, the mordenite molecular sieve product.

2. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: The method for pretreating the waste Y molecular sieve in step a) is: grinding the waste Y molecular sieve to make the crystal particle size less than 10 μm, and the silicon-aluminum ratio (SiO2 / Al2O3) of the waste Y molecular sieve is 5-100.

3. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: In the step (b), the template agent is one of piperazine, tetraethylammonium hydroxide, glycerol, ethylene glycol and polyethylene glycol, or a combination thereof.

4. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: In the step (b), the alkali source is sodium hydroxide or potassium hydroxide.

5. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: In the step (b), the pH of the gel solution is 13-14, and the reaction temperature is 40-60° C. and stirred for 1-4 h.

6. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: In the step (b), the molar ratio of template agent / waste Y molecular sieve is 1:2-20, and the molar ratio of waste Y molecular sieve / deionized water is 1:20-40.

7. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: The hydrothermal crystallization reaction temperature is 140-220°C, and the crystallization time is 12-72 h.

8. The method for preparing mordenite molecular sieve from waste Y molecular sieve according to claim 1, characterized in that: In the step d), the calcination temperature is 500-550° C. and the calcination time is 3-6 h.

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