Green preparation method of high silica-alumina ratio hydrogenous molecular sieve

Abstract

The invention relates to the technical field of molecular sieve preparation, and discloses a green preparation method of a high silica-alumina ratio hydrogenous molecular sieve, comprising the following steps: mixing and crystallizing a silicon source with Na2O less than 100ppm, an aluminum source, water and hexamethonium hydroxide, then cooling, and performing suction filtration to obtain an EU-1molecular sieve semi-finished product and molecular sieve crystallization mother liquor, and drying and roasting the EU-1 molecular sieve semi-finished product to obtain the hydrogenous EU-1 molecular sieve. According to the invention, in a sodium-free system, a hydrogenous zeolite molecular sieve is obtained by high temperature roasting at 400-600 DEG C, production process steps are reduced, water consumption and energy consumption are saved, and production time is saved; compared with a sodium-containing ion synthesis system, in the system, low-positive-charge-density quaternary ammonium cation is easier to match with a high silica-alumina molecular sieve framework with low negative charge, and a molecular sieve with high silica-alumina ratio phase region SiO2 / Al2O3 being equal to 100-500 and sodium oxide content being lower than 500ppm is synthesized.

Description

technical field [0001] The invention relates to the technical field of molecular sieve preparation, in particular to a green preparation method of a high silicon-aluminum ratio hydrogen type molecular sieve. Background technique [0002] Zeolite molecular sieve is a kind of aluminosilicate crystal, which is widely used in adsorption, catalysis and ion exchange due to its unique pore structure, suitable acid distribution, good thermal and hydrothermal stability, and ultra-high specific surface area. field. In recent years, with the increasingly severe environmental pressure, how to make green and efficient production has become the first task of all walks of life. Among them, the chemical industry, as the main polluting industry of wastewater, waste gas and waste, has become a concern of the government and relevant researchers. [0003] There are many synthesis methods of zeolite molecular sieves: mainly hydrothermal synthesis, steam phase inversion, solvent-free synthesis,...

AI Technical Summary

Problems solved by technology

At present, the synthesis of zeolite molecular sieves mainly includes water source, alkali source, template agent, silicon source and aluminum source. Among them, the alkali source generally adopts inorganic alkali such as sodium hydroxide, and most of the silicon and aluminum sources use low-cost raw materials with high sodium ions. Synthetic products It is a sodium zeolite, but the molecular sieve catalyst, as an active component of an acid-catalyzed mechanism, needs to undergo an ion exchange step, which is time-consuming, energy-consuming, and water-consuming; the patent (CN 103626200A) proposes a one-step synthesis of hydrogen-type EUO by a sodium-free method The method of zeolite has few ion exchange steps, the method is simple, and has the disadvantages of reducing energy consumption, saving time, and less waste water.

Most of the molecular sieve templates are relatively cheap bromine or chlorine-containing quaternary ammonium salts. If the mother liquor of the system is recycled, it will inevitably lead to the enrichment of inorganic salts such as sodium bromide, which will destroy the charge balance of the molecular sieve synthesis system and make recycling route failed

[0004] So far, EU-1 molecular sieves have reported high silicon-aluminum ratio (SiO 2 / Al 2 o 3 =100-300), Xu et al. (Xu Q, Gong Y, Xu W, et al. Synthesis of high-silica EU-1 zeolite in the presence of hexamethonium ions: a seeded approach for inhibiting ZSM-48[J]. Journal of Colloid & Interface Science, 2011, 358(1):252-260.) reported that the pure-phase EU-1 molecular sieve with a silicon-aluminum specific phase region of 50-1800 was synthesized by using the seed crystal method to reduce the activation energy of nucleation, but this method was expensive Seed, high cost; Li et al. (LiX, Liu X, Zhang Y, et al. Controllable synthesis of EU-1 molecular sieve with high SiO 2 / Al 2 o 3 , ratios in thermodynamic stable sol system[J]. Journal of Porous Materials, 2016, 23(6):1-9.) A high-silicon-aluminum phase zone EU-1 was synthesized using common tetraethylammonium hydroxide as an alkali source Molecular sieve, but tetraethylammonium hydroxide is only used as alkali source in this method, which introduces the second organic matter in the synthesis system, which is not conducive to environmental protection and economic cost

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