A kind of ferrierite molecular sieve and its preparation method and application

Abstract

The invention provides a ferrierite molecular sieve, a preparation method thereof and an application. The preparation method includes the steps: mixing silicon sources, alkalinity conditioning agents, aluminum sources, template agents and water to form uniform sol; controlling the molar ratio of SiO2, Al2O3, R, Na2O to H2O to be 1.0:(0.005-0.10):(0.05-1.2):(0.03-0.50):(5.0-100.0), and enabling a pH (potential of hydrogen) value to be lower than 12.8; performing pre-crystallization, crystallization, drying and calcination to obtain molecular sieve raw powder; performing acid treatment on the obtained molecular sieve raw powder; mixing the molecular sieve raw powder, the template agents and the water or further mixing the molecular sieve raw powder, the template agents, the water and the silicon sources to form water solution; performing water-heat treatment, drying and calcination to obtain the ferrierite molecular sieve. R is the template agents. The prepared ferrierite molecular sieve is high in relative crystallinity and silica alumina ratio, large in specific surface area and crystal particle and adjustable in acidity and has excellent selectivity and stability when being applied to linear-chain olefin skeletal isomerization reaction.

Description

technical field [0001] The invention relates to a ferrierite molecular sieve (FER) and its preparation method and application, belonging to the field of ferrierite molecular sieve modification. Background technique [0002] US4016245 announced the synthesis of ferrierite molecular sieve for the first time. The basic structural unit of ferrierite molecular sieve is a five-membered ring, and the five-membered ring is cleverly connected by a ten-membered ring and a six-membered ring. The structural feature of ferrierite is composed of a two-dimensional pore system composed of a ten-membered ring with a dimension of 0.42×0.54nm and an eight-membered ring with a dimension of 0.35×0.48nm. The average pore diameter is 0.6nm, which belongs to the orthorhombic crystal system. [0003] Ferrierite has been widely used in the reaction processes of aromatics alkylation, olefin oligomerization, xylene isomerization, reforming liquid and naphtha modification, and fuel oil pour point reduct...

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Problems solved by technology

However, the molecular sieve obtained from this case has low selectivity and poor stability in the skeletal isomerization reaction of linear olefins.

[0005] CN1491888A discloses a method for synthesizing ferrierite with pyridine as template agent, although the molecular sieve synthesized in this case has the advantages of high silicon-alumina ratio and large specific surface area, but similarly, the molecular sieve obtained in this case has the advantage of being in the linear olefin Low selectivity and poor stability in skeletal isomerization reactions

[0007] The main problems existing in the above-mentioned existing ferrierite synthesis method or its modification technology are: the obtained molecular sieve has low selectivity and poor stability in the linear olefin skeletal isomerization reaction

[0008] CN103058222B discloses a method for preparing ZSM-35 molecular sieve. The main feature of the method is that the ZSM-35 molecular sieve is treated with alkali to prepare a structure-directing agent, and the directing agent is added to the silica-alumina gel, and after hydrothermal crystallization The ZSM-35 molecular sieve was prepared, which has a high degree of crystallinity and effectively avoids the generation of miscellaneous crystals. Although the synthesized ZSM-35 molecular sieve has a large grain size, the crystallization process requires a directing agent, and the case did not provide The field of use of this material

[0009] CN104418357B discloses a method for preparing small-grain ZSM-35 molecular sieves. The main feature of the method is that a molecular sieve with a length of 200nm to 600nm and a thickness of 100nm is synthesized without adding organic additives or inorganic guiding agents other than templates in the raw materials. However, the disadvantage of this method is that it also requires seed orientation, and as a material, it does not specify the field of use

CN104495869B discloses a method for preparing ZSM-35 molecular sieve. The main feature of the method is to mix the silicon source, aluminum source, alkali source, templating agent and water uniformly, and crystallize at 15-80°C for 5-30 hours. Continue crystallization at 150-200°C for 10-30 hours, use ethylenediamine as a template, and control the synthesis of small-grain ZSM-35 molecular sieves through two-stage crystallization, the minimum size of which can reach 0.5 μm. The amount of template used in this method Large, complex process, long crystallization time, and does not provide the application field of the material

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