CN-121974370-A - Synthetic method and application of high-silicon SSZ-13 molecular sieve

Abstract

The application discloses a synthesis method and application of a high-silicon SSZ-13 molecular sieve. The synthesis method comprises the steps of stirring a mixture containing an organic template agent, a silicon source, an aluminum source, inorganic salt/inorganic alkali and water to obtain gel, and crystallizing to obtain the high-silicon SSZ-13 molecular sieve, wherein the aluminum source is at least one of SAPO molecular sieves. By adopting the SAPO molecular sieve as an aluminum source, the SSZ-13 molecular sieve with high silicon-aluminum ratio can be synthesized, and Si/Al modulation in a wider range is realized. The catalyst is applied as a molecular sieve catalyst for preparing olefin (MTO) from methanol, and shows excellent performance in MTO reaction.

Inventors

• YANG MIAO
• WANG XINYI
• LIU TONGRUI
• LI BING
• WANG YE
• TIAN PENG
• LIU ZHONGMIN

Assignees

• 中国科学院大连化学物理研究所
• 榆林中科洁净能源创新研究院

Dates

Publication Date

20260505

Application Date

20241025

Claims (10)

1. 1. A method for synthesizing a high silicon SSZ-13 molecular sieve, which is characterized by comprising the following steps: stirring a mixture containing an organic template agent, a silicon source, an aluminum source, inorganic salt/inorganic alkali and water to obtain gel, and crystallizing to obtain the high-silicon SSZ-13 molecular sieve; the aluminum source is selected from at least one of SAPO molecular sieves; The molar ratio of the gel is as follows: SiO 2 ：Al 2 O 3 ：Na 2 O：R：H 2 O＝1：0.00083～0.035：0.03～0.10：0.03～0.22：5～20; Wherein, the silicon source is calculated by SiO 2 , the aluminum source is calculated by Al 2 O 3 , the inorganic salt/inorganic base is calculated by Na 2 O, and R refers to an organic template agent.
2. 2. The synthesis method according to claim 1, wherein the aluminum source is selected from at least one of SAPO-5 molecular sieve, SAPO-11 molecular sieve, SAPO-34 molecular sieve, SAPO-18 molecular sieve, DNL-6 molecular sieve.
3. 3. The synthesis method according to claim 1, wherein the organic template is at least one selected from the group consisting of N, N-trimethyl adamantane ammonium hydroxide, benzyl trimethyl ammonium hydroxide, tetraethylammonium hydroxide, choline, cu-tetraethylenepentamine; The silicon source is at least one selected from chromatographic column silica gel, tetraethoxysilane, silica sol, water glass and white carbon black; the inorganic salt/inorganic base is sodium chloride/sodium hydroxide.
4. 4. The synthesis method according to claim 1, wherein the crystallization condition is that the crystallization temperature is 140-170 ℃ and the crystallization time is 24-72 h; preferably, the crystallization is rotational crystallization.
5. 5. The synthesis method according to claim 1, wherein the gel is prepared by dissolving inorganic salt/inorganic base and organic template agent in water, mixing uniformly, adding silicon source, stirring, adding SAPO molecular sieve as aluminum source, and stirring.
6. 6. The method of claim 1, further comprising the steps of drying and calcining after crystallization.
7. 7. The synthesis method according to claim 1, wherein the silicon-aluminum ratio Si/Al of the high-silicon SSZ-13 molecular sieve is 20-300.
8. 8. The use of the high-silicon SSZ-13 molecular sieve synthesized by the synthesis method according to any one of claims 1-7 as an acid catalytic reaction catalyst.
9. 9. The method according to claim 8, wherein the high-silicon SSZ-13 molecular sieve is used as an acid catalyst after being subjected to ammonium exchange and roasting in sequence.
10. 10. The use according to claim 8, characterized in that it is applied in MTO catalytic reactions.

Description

Synthetic method and application of high-silicon SSZ-13 molecular sieve Technical Field The application relates to a synthesis method and application of a high-silicon SSZ-13 molecular sieve, belonging to the field of molecular sieve synthesis and catalysis. Background Molecular sieves are widely used in the fields of adsorption separation, ion exchange, industrial catalysis and the like due to the regular and ordered molecular scale pore channel structure, adjustable acid property, high specific surface area and adsorption capacity, cation exchange property, good shape selectivity of the pore channel, higher thermal stability and chemical stability and the like. SSZ-13 molecular sieves are microporous aluminosilicates with the CHA topology and were hydrothermally synthesized using N, N, N-trimethyl alkylammonium hydroxide (TMADaOH) as a templating agent as reported in 1985 by the chemist Zones et al (Zones S I. Zeolite SSZ-13and its method of preparation[P) of Chevron, U.S.A. The inside of the crystal is alternately connected by double six-membered rings and cha cages to form a specific three-dimensional pore canal structure, the pore canal size is 0.38nm multiplied by 0.38nm, the specific surface area is about 700cm 2/g, and the catalyst has excellent catalytic performance in the selective catalytic reduction of nitrogen oxides and the catalytic reaction of preparing low-carbon olefin (MTO) from methanol due to the specific pore canal structure and the larger specific surface area. For MTO reaction, SSZ-13 molecular sieve with higher acid content (low SiO 2/Al2O3 ratio) is easy to generate side reactions such as hydrogen transfer, so that the stability of the catalyst is always seriously affected, the selectivity of low-carbon olefin is reduced, and the synthesis of high-crystallinity high-silicon SSZ-13 molecular sieve is still a pursued goal. When SSZ-13 is synthesized by a traditional hydrothermal method, N, N, N-trimethyl adamantyl ammonium hydroxide is the most commonly used template agent, so that the use amount is large and the price is high. Meanwhile, even if the reaction time is prolonged or the silicon-aluminum feeding ratio is increased, the silicon-aluminum ratio of the product is still difficult to increase, and the product is often accompanied with mixed crystals and low solid yield. In order to make SSZ-13 molecular sieves better for use, researchers have conducted extensive research on the synthesis of SSZ-13 molecular sieves. The introduction of fluoride allows for modulation of the SSZ-13 molecular sieve silica to alumina ratio in the range of 20- +.. However, fluoride ions have serious environmental pollution, which limits the amplified synthesis production of high-silicon SSZ-13 molecular sieves, and high-silicon SSZ-13 (Hasna AJ, miyake K Kaito O, et al, microporous and Mesoporous Materials,2019,278,322-326) can be synthesized in a fluorine-free and seed crystal-free system by using a dry gel conversion method, but the method still has the problems of complex operation and the like. In recent years, an intergranular conversion method has also been developed to synthesize an SSZ-13 molecular sieve, i.e., to convert and synthesize the SSZ-13 molecular sieve in situ using other types of silicon-aluminum molecular sieves as silicon and aluminum sources. The chemical composition of the synthesized product of this process is strongly dependent on the starting molecular sieve. In order to raise the silicon-aluminum ratio of the product, the molecular sieve parent, such as Y-type zeolite, needs to be treated with high-temperature steam or acid (Martin N, moliner M, corma A.chemical Communications,2015,51 (49): 9965-9968) in advance to raise the silicon-aluminum ratio, and even so, the silicon-aluminum ratio of the SSZ-13 zeolite molecular sieve synthesized by the method is still limited to 2.5-16. Disclosure of Invention The application provides a method for synthesizing a high-silicon SSZ-13 molecular sieve and application thereof, wherein the SAPO molecular sieve is directly used as an aluminum source, the high-silicon CHA SSZ-13 molecular sieve can be synthesized in a wider phase region by adjusting the adding amount of the SAPO molecular sieve, the silicon-aluminum ratio and the solid phase yield are both obviously improved, and the high-silicon SSZ-13 molecular sieve shows excellent catalytic performance in catalyzing MTO reaction. According to a first aspect of the present application, a method for synthesizing a high silicon SSZ-13 molecular sieve is provided. A method for synthesizing a high silicon SSZ-13 molecular sieve, the method comprising: stirring a mixture containing an organic template agent, a silicon source, an aluminum source, inorganic salt/inorganic alkali and water to obtain gel, and crystallizing to obtain the high-silicon SSZ-13 molecular sieve; the aluminum source is selected from at least one of SAPO molecular sieves; The molar ratio of the gel is as follows: SiO2：