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CN-121990592-A - SSZ-13 molecular sieve and preparation method and application thereof

CN121990592ACN 121990592 ACN121990592 ACN 121990592ACN-121990592-A

Abstract

The invention relates to the field of molecular sieve preparation, and discloses an SSZ-13 molecular sieve, a preparation method and application thereof. The preparation method comprises the following steps of 1) carrying out a first crystallization reaction on a first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent and water to obtain a potassium type accelerator, and 2) carrying out a second crystallization reaction on a mixture containing a second aluminum source, a second silicon source, an alkali source, the organic template agent, water and the potassium type accelerator to obtain a crystallization product, wherein the molar ratio of SiO 2 ：Al 2 O 3 ：K 2 O：R：H 2 O in the potassium type accelerator is 1:0.1-0.4:0.6-1.5:0.02-0.15:60-140, and R is the organic template agent. The method can stably realize the production of the SSZ-13 molecular sieve, the prepared SSZ-13 molecular sieve has relatively dispersed micron-sized crystals which are nearly regular hexahedral, and the catalyst prepared by the molecular sieve has excellent catalytic activity and good hydrothermal stability.

Inventors

  • CUI KAI
  • LI KEZHI
  • HAN SHUAI
  • REN JING
  • YANG ZHENYU
  • YANG LIU

Assignees

  • 中国石油化工股份有限公司
  • 中国石化催化剂有限公司

Dates

Publication Date
20260508
Application Date
20241101

Claims (10)

  1. 1. A method for preparing an SSZ-13 molecular sieve, which is characterized by comprising the following steps: 1) Carrying out a first crystallization reaction on a first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent and water to obtain a potassium type accelerator; 2) Performing a second crystallization reaction on a mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water and the potassium accelerator to obtain a crystallization product, Wherein, in the potassium type accelerator, the molar ratio of SiO 2 ：Al 2 O 3 ：K 2 O：R：H 2 O is 1:0.1-0.4:0.6-1.5:0.02-0.15:60-140, and R is an organic template agent.
  2. 2. The production method according to claim 1, wherein in step 2), a second mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, and water is contacted with the potassium-type accelerator to perform the second crystallization reaction; Preferably, in the potassium type accelerator, the molar ratio of SiO 2 ：Al 2 O 3 ：K 2 O：R：H 2 O is 1:0.1-0.3:0.6-1.2:0.02-0.10:60-120, and R is an organic template agent; Preferably, the molar ratio of the second silicon source calculated as SiO 2 , the second aluminum source calculated as Al 2 O 3 , the alkali source calculated as metal oxide, the organic template R and H 2 O in the second mixture is 1:0.02-0.17:0.05-0.5:0.01-0.15:5-90, more preferably 1:0.04-0.08:0.2-0.4:0.04-0.05:30-40; Preferably, in step 2), the potassium-type promoter is used in an amount of 0.02 to 1% by weight, more preferably 0.05 to 0.1% by weight, of the second mixture.
  3. 3. The production method according to claim 1, wherein in step 1), the first crystallization reaction is a dynamic crystallization reaction; Preferably, the conditions of the first crystallization reaction comprise 20-120 ℃ of temperature, 5-50h of time and 50-500rpm of rotating speed; preferably, the conditions of the first crystallization reaction include a reaction at a rotation speed of 100-300rpm at 30-90 ℃ for 2-30 hours followed by a reaction at 90-150 ℃ for 0.2-10 hours; more preferably, the conditions of the first crystallization reaction include a reaction at a rotation speed of 150 to 200rpm at 40 to 80 ℃ for 5 to 30 hours and a reaction at 90 to 120 ℃ for 0.5 to 4 hours.
  4. 4. The process according to claim 1, wherein in step 2), the conditions of the second crystallization reaction include a temperature of 100 to 220 ℃ for a time of 5 to 144 hours; preferably, the conditions of the second crystallization reaction comprise a temperature of 120-180 ℃ and a crystallization time of 24-96 hours; Preferably, the second crystallization reaction is a static crystallization reaction.
  5. 5. The production method according to any one of claims 1 to 4, wherein the method further comprises: Drying and roasting the crystallized product obtained in the step 2); preferably, the drying conditions include a temperature of 50-150 ℃ for 8-24 hours; preferably, the roasting condition comprises a temperature of 400-700 ℃ and a time of 2-10h.
  6. 6. The production method according to any one of claims 1 to 4, wherein the first aluminum source is selected from aluminum hydroxide and/or aluminum sulfate; preferably, the first silicon source is selected from one or more of silica sol, white carbon black and amorphous silica; preferably, the potassium source is selected from one or more of potassium hydroxide, potassium sulfate, potassium chloride and potassium nitrate; Preferably, the organic template is selected from one or more of N, N, N trimethyl 1 adamantylammonium hydroxide, benzyltrimethylammonium hydroxide, N, N, N dimethylethylcyclohexylammonium bromide, tetraethylammonium hydroxide, tetramethylammonium hydroxide and choline chloride, more preferably N, N, N trimethyl 1 adamantylammonium hydroxide; Preferably, the second aluminum source is selected from one or more of aluminum hydroxide, aluminum sulfate, sodium metaaluminate, and aluminum oxide; Preferably, the second silicon source is selected from one or more of silica sol, white carbon black, water glass, sodium silicate, potassium silicate and amorphous silica; Preferably, the alkali source is selected from sodium hydroxide and/or potassium hydroxide.
  7. 7. An SSZ-13 molecular sieve, wherein the SSZ-13 molecular sieve is prepared by the method of any one of claims 1-6.
  8. 8. The SSZ-13 molecular sieve of claim 7, wherein the crystallites of the SSZ-13 molecular sieve have a near-regular hexahedral structure and the crystallite size of the SSZ-13 molecular sieve is 0.5-1.5 μιη, preferably 0.8-1.2 μιη; Preferably, the SSZ-13 molecular sieve has a silica to alumina ratio of 9-25:1, more preferably 14-22:1; Preferably, the SSZ-13 molecular sieve has a crystallinity of 98 to 106%, more preferably 104 to 106%.
  9. 9. A Cu-SSZ-13 molecular sieve catalyst, wherein said Cu-SSZ-13 molecular sieve catalyst comprises an SSZ-13 molecular sieve of claim 7 or 8.
  10. 10. Use of the SSZ-13 molecular sieve of claim 7 or 8 or the Cu-SSZ-13 molecular sieve catalyst of claim 9 in denitration.

Description

SSZ-13 molecular sieve and preparation method and application thereof Technical Field The invention relates to the field of molecular sieve preparation, in particular to an SSZ-13 molecular sieve, and a preparation method and application thereof. Background With the rapid development of economy, NO x emissions have also increased at an unprecedented rate. Nitrogen oxides (NO x) from both mobile and stationary sources present a series of environmental problems, such as the oxidative conversion of NO x to nitric acid in the atmosphere, which is one of the causes of acid rain, photochemical reactions between NO x and other contaminants in the atmosphere, which can cause photochemical smog pollution, and NO x can also reduce ozone in the stratosphere, which can increase the amount of ultraviolet radiation reaching the earth. In addition, NO x can enter the deep part of the lung of the human body through breathing, so that diseases such as bronchitis or emphysema and the like are caused, and the human body health is endangered. The problem of disposal of NO x is urgent. Among them, ammonia selective catalytic reduction NO x(NH3 -SCR) technology is an effective NO x removal technology. Commercial V 2O5-WO3/TiO2 catalysts have been widely used for fixed source denitration and exhibit excellent NO x removal efficiency in the medium temperature range (300-400 ℃). However, the catalyst exhibits some drawbacks such as low high temperature selectivity, narrow operating temperature range, and toxicity of vanadium. SSZ-13 molecular sieve is widely applied in NO x removal (especially diesel vehicle denitration) because of the advantages of large specific surface area, rich ion exchange sites, strong surface acid sites, molecular shape selective effect and the like. SSZ-13 molecular sieves were initially prepared by hydrothermal synthesis from the American chemist Zones in the mid-80 s of the 20 th century, and numerous studies were then carried out to optimize the improved SSZ-13 molecular sieve synthesis process, but so far, enterprises capable of mass production of SSZ-13 molecular sieve raw powders were extremely rare, mainly because the crystal form of SSZ-13 molecular sieves was difficult to control, and further metal-supported SSZ-13 catalysts were difficult to achieve a balance of activity and stability, for example, cu-SSZ-13 catalysts which are generally excellent in activity had a problem of poor hydrothermal stability in most cases. In this regard, huawang Zhao and the like synthesize the SSZ-13 molecular sieve by taking the SAPO-34 microcrystal as a seed crystal, thereby further preparing the Cu-SSZ-13 catalyst, and compared with a product synthesized by taking the SSZ-13 microcrystal as a seed crystal, the hydrothermal stability of the obtained catalyst is obviously improved (Journal of Catalysis 377 (2019): 218-223, DOI: 10.1016/j.jcat.2019.07.023), and further, for example, yunzheng Wang and the like adopt the SAPO-18 microcrystal as the seed crystal to increase the aluminum pair content in the SSZ-13 molecular sieve with a low silicon-aluminum ratio based on an RNA transcription mechanism, thereby effectively improving the hydrothermal stability of the Cu-SSZ-13 catalyst (Angewande 62 (2023): e202306174, DOI: 10.1002/anie.2023067174). However, both of the above methods use phosphorus-containing seed crystals, which tends to cause a significant increase in the difficulty of treating the production wastewater. In addition, in the prior art, innovative methods such as a mixed template method are also used for preparing the SSZ-13 molecular sieve, but the mixed template agent has not yet realized industrial production, and the combination of multiple template agents is unfavorable for the subsequent mother liquor recycling, so that the method is not suitable for large-scale industrial production. On the other hand, the SSZ-13 molecular sieve reported by the current research work is mostly nano-scale agglomerated irregular crystal particles, the structure and the performance of the molecular sieve are unstable, and the service application prospect is not clear. Based on the current situation, the development of an SSZ-13 molecular sieve with excellent activity and good hydrothermal stability is an important task to be completed currently and urgently. Disclosure of Invention The invention aims to overcome the problem that the activity and the hydrothermal stability of an SSZ-13 molecular sieve are difficult to combine in the prior art, and provides an improved preparation method of the SSZ-13 molecular sieve, wherein substances such as phosphorus and the like which obviously increase the wastewater treatment difficulty are not required to be introduced, and a combined template agent with complex components is not required to be used, so that the SSZ-13 molecular sieve can be stably produced, and the prepared SSZ-13 molecular sieve has relatively dispersed micron-sized crystals which are nearly hexahedral, and t