Method for synthesizing large-grain and highly-dispersed 4A zeolite

Abstract

The invention discloses a method for synthesizing large-grain and highly-dispersed 4A zeolite. The method comprises the following steps of: preparing materials, gelatinizing, crystallizing, washing, and drying. In order to synthesize the large-grain and highly-dispersed 4A zeolite, a certain silicon-to-aluminum ratio is kept, a water-to-sodium ratio is properly increased, and a relatively low sodium-to-silicon ratio is controlled in the aspect of a raw material ratio; in order to ensure that grains are large and uniform, N-atom-containing organic alkali or an anionic surfactant is properly added into ingredients; in order to synthesize a 4A molecular sieve with large grains and high dispersibility, two-section crystallization is adopted, the first section is dynamic crystallization, the temperature is controlled to be between 70 and 85 DEG C to control the number of grain seeds and achieve a high dispersion degree among the seeds, and the second section is static crystallization to create conditions for grain growth only; and a certain amount of builder is added at the late stage of washing, so that the pH value of raw powder of the molecular sieve can be reduced, and bonded ions can be neutralized due to weak acidity and enter a solution to meet the requirement of dispersibility.

Description

technical field [0001] The invention relates to a method for synthesizing 4A zeolite in the chemical industry, in particular to a method for synthesizing large-grain and highly dispersed 4A zeolite. Background technique [0002] In addition to existing in nature, 4A zeolite is the oldest, most used and most mature artificial synthetic molecular sieve. Now the general 4A molecular sieve grains are between 1μm and 5μm. In addition to being replaced with 3A and 5A, it is also widely used in drying, coating and plastic modification. When it is applied in the form of activated powder, it is affected by too small crystal grains and poor dispersion. Too small crystal grains have poor thermal stability, which is not suitable for high-temperature operation in the application process and affects its adsorption performance. However, the small crystal grains in the synthesis process will also form a large number of crystal grains to bond with each other, and the dispersion is not good,...

AI Technical Summary

Problems solved by technology

When it is applied in the form of activated powder, it is affected by too small crystal grains and poor dispersion. Too small crystal grains have poor thermal stability, which is not suitable for high-temperature operation in the application process and affects its adsorption performance. However, the small crystal grains in the synthesis process will also form a large number of crystal grains to bond with each other, and the dispersion is not good, which affects the dispersion during use.

The most direct manifestation is: although the crystal grains are not large, the value of dv50 in the particle size distribution test is far greater than the grain size, making it difficult for manufacturers to accept

If the activated powder with bonding phenomenon is mechanically crushed, the crystal grains will be destroyed, making the powder irregular in shape, and also affecting its use effect