Synthesis method and application of submicron X-type molecular sieve

Abstract

The invention relates to a synthesis method and an application of a submicron X-type molecular sieve. The molecular sieve takes a silica solution as a silicon source to prepare a crystallization director, water glass and sodium metaaluminate or aluminum hydroxide and sodium hydroxide are used to prepare a molecular sieve synthesis mother solution, the director is added into the mother solution to age the mother solution for a certain period of time, then a weak-polarity water-soluble dispersing agent is added into the mixture, the mixture is stirred uniformly, and the submicron X-type molecular sieve is obtained through microwave assistance and hydrothermal crystallization in a closed container. The X-type molecular sieve prepared through the method is small in grain size, the synthesis time is greatly shortened, and the production cost is lowered. The molecular sieve is applied to separation and adsorption of hydrocarbon, and particularly has a technical characteristic of removing in depth the oxygen-bearing impurities during the purification of olefin in a MTO (Methanol To Olefin) process, and the molecular sieve prepared through the method has the characteristics of large adsorption capacity and easiness in regeneration, and the method is applicable to industrial production.

Description

technical field [0001] The invention belongs to the technical field of molecular sieves, and in particular relates to a method for synthesizing a submicron X-type molecular sieve and its application. Background technique [0002] Because of its specific structure, X-type molecular sieves are widely used in industry, such as gas drying, adsorption separation and purification in air separation, wastewater treatment of heavy metal pollution, etc. How to control the performance of molecular sieves is always the focus of research and development. , SiO 2 / Al 2 o 3 Ratio, as an important influencing factor, first received widespread attention. Such as CN102417190A adopts active silicon source method to prepare SiO 2 / Al 2 o 3 For NaX-type zeolites smaller than 2.1, the active silicon source is prepared in advance and placed for 1 to 10 days, and then fed into the preparation. The preparation cycle is long and the process links are many, which is not conducive to industrial p...

AI Technical Summary

Problems solved by technology

Such as CN102417190A adopts active silicon source method to prepare SiO 2 / Al 2 o 3 For NaX-type zeolites smaller than 2.1, the active silicon source is prepared in advance and placed for 1 to 10 days, and then fed into the preparation. The preparation cycle is long and the process links are many, which is not conducive to industrial production.

CN1191199C prepares SiO by reducing the preparation temperature of the directing agent and the gelation temperature of the zeolite mother liquor 2 / Al 2 o 3 X-type zeolite greater than 2.4, CN1448338A uses low-temperature guiding agent and low-temperature aging method to prepare SiO 2 / Al 2 o 3 For X-type zeolites greater than 2.4, both require certain refrigeration equipment, which increases the preparation cost

In the field of adsorption and separation, diffusion is a more important issue. Under dynamic adsorption conditions, large-grained molecular sieves tend to have a significantly lower dynamic adsorption capacity than static adsorption due to their longer diffusion channels.

In order to meet a certain amount of adsorption, the method of increasing the relative amount of molecular sieve is often used in the adsorbent, but this leads to the accumulation of adsorption heat, which causes problems such as easy deactivation and frequent regeneration of the adsorbent.

Images