Method for preparing ZSM-34 and heteroatom substituted molecular sieve thereof by using crystal seed synthesis method

Abstract

The invention relates to a molecular sieve preparation method, in particular to a method for synthesizing a ZSM-35 molecular sieve by using a crystal seed method. The method comprises the following steps of: uniformly mixing deionized water and an aluminum source together, adding a potassium source and NaOH, adding white carbon black while stirring, continuously stirring until the solution is uniform and becomes silica-alumina gel, adding a ZSM-35 molecular sieve crystal seed into the silica-alumina gel, and stirring; placing the mixture in a reaction kettle, crystallizing for 3 hours to 5 days at 100-180 DEG C, or crystallizing for 1-10 days at 70-100 DEG C; filtering the product by suction, and drying to obtain the ZSM-34 molecular sieve. The method not only maintains good crystallinity and purity, but also has good catalytic reaction activity. The entire production process not only does not use any organic template agents, but also can greatly shorten crystallization time by using the crystal seed method. Thus, unnecessary loss in the production process is reduced, the product also has larger specific surface area, and the product has potential application value to certain important catalytic reactions. The inorganic raw materials adopted during product are all friendly to environment and cheap.

Description

technical field [0001] The invention belongs to a method for preparing molecular sieves, in particular to a method for preparing ZSM-34 and heteroatom-substituted molecular sieves by a seed crystal synthesis method. Background technique [0002] Because of its open structure and large surface area, molecular sieves are widely used in many fields, such as ion exchange, adsorption and separation, host-guest chemistry, etc., and have been widely used in petrochemical and fine chemical industries. Rubin et al first used ((CH 3 ) 3 NCH 2 CH 2 OH) as a template to synthesize ZSM-34 molecular sieve (USP4,086,186). ZSM-34 is a zeolite (8-membered ring Channels and 12-membered rings channels crossed) and erionite (three-dimensional 8-membered ring A symbiont of the channel). Because of its good catalytic activity and selectivity in the methanol conversion reaction (MTO), it has aroused great interest of researchers. [0003] Since the synthesis of ZSM-34 zeolite molecular ...

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Problems solved by technology

Recently, Xiao Fengshou and others successfully synthesized ZSM-34 (CN Patent No.200710056022.X.) using L-directing agent without organic template. Although the cost is reduced, it is necessary to prepare L-directing agent and aluminum sulfate solution. The disadvantage of longer crystallization time is a factor that must be considered in industrial applications

In addition, there are still few reports on the in situ synthesis of heteroatom-doped ZSM-34 molecular sieves without organic templates.

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