Preparation method of nanometer stepped hole mordenite molecular sieve

Abstract

The invention discloses a preparation method of a nanometer stepped hole mordenite molecular sieve. The method comprises the following steps: dissolving sodium hydroxide in water and then adding a silicon source at room temperature to stir for 0.5-1.5 h to obtain alkaline silicon source solution; adding an aluminum source dissolved by using the water into the alkaline silicon source solution, stirring for 1 h at the room temperature to form uniform silicon and aluminum mixed solution, adding a mesoporous soft template (R) for 1 h, then adding a seed crystal (M) and stirring for 1 h to form a gel mixture, and then dynamically crystallizing at 100-180 DEG C for 12-96 h; cooling, performing extraction filtration and washing the product after crystallization until pH is about 7, drying at 100 DEG C for 12 h, roasting at the constant temperature of 110 DEG C for 3 h and then rising temperature to 500 DEG C to roast for 3 h to obtain a nanometer stepped hole mordenite product. The mordenite molecular sieve prepared by the invention has the typical nanometer stepped hole characteristic, and the hydrodealkylation performance of the Pt / MOR catalyst loaded with the sieve as a carrier is obviously improved.

Description

technical field [0001] The invention relates to a preparation method of a nanometer graded hole mordenite molecular sieve, in particular, using a mesoporous soft template agent to hydrothermally synthesize the nanometer graded hole mordenite molecular sieve in one step. Background technique [0002] Nanoparticles refer to particles with a size ranging from 1 to 100 nm. Nano zeolite molecular sieves have a larger outer surface area and more pores exposed to the outside. Molecular sieves with a pore size between 2 and 50 nm are called mesoporous molecular sieves. [0003] Mordenite (MOR) is a microporous aluminum silicate molecular sieve with uniform pore size, good acid resistance and heat resistance. Therefore, MOR molecular sieve has been widely used in hydrocracking, isomerization, alkylation and Catalysts for processes such as reforming and also for the separation of gas or liquid mixtures. The ideal unit cell composition of MOR molecular sieve is Na 8 Al 8 Si 40 o ...

AI Technical Summary

Problems solved by technology

[0004] The preparation of nano-sized mordenite (MOR) molecular sieves has been reported. In Chinese patent CN1837046A, Xing Shujian et al. used mordenite as a crystal seed and prepared nano-sized mordenite molecular sieves by segmental crystallization, but the synthesis steps were relatively cumbersome.

Beatriz et al. synthesized a nano needle-like mordenite molecular sieve with a grain width of 63nm and a length of 24nm, but it required a long crystallization time

CN103601213A invented a method for preparing nano flake clustered mordenite molecular sieve, the preparation method has low cost and low environmental pollution, but the silicon-aluminum ratio of the synthesized molecular sieve is low

However, this study uses a multi-stage variable temperature and multi-component soft template agent, which is complicated to operate, which greatly increases the production cost of mordenite, and is not suitable for industrialization (Wang Qiao, Liu Xianling, Wang Lei, etc. Synthesis and characterization of mordenite with mesoporous structure[ J]. Journal of Silicates, 2012,40(3):425-431.)

CN103482645A discloses a method for preparing hierarchically porous nano-mordenite molecular sieves using surfactants as soft templates. The method utilizes novel cationic surfactants as soft templates to hydrothermally synthesize hierarchically porous nano-mordenite molecular sieves, but the synthesized The mordenite has more miscellaneous peaks

Because the larger water-to-silicon ratio reduces the concentration of the crystallization solution, which is not conducive to the generation of small-grain MOR, and no seed crystals are added, the crystal grains synthesized by this method are needle-shaped and large in size (50~ 100nm) and relatively small specific surface area

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