What Are The Differences Between Activated Alumina And Molecular Sieves

First, structural differences

The molecular formula of activated alumina is: al2o3-x (OH) 2x, 0 <x <0.8. The pore structure distribution of activated alumina is relatively disordered, and the pore size distribution ratio is generally: micropores, mesopores and macropores. The pore distribution of activated alumina is uneven.

But molecular sieves are different. Molecular sieve: (m) 2 / no · Al2O3 · xsio2 · ph2o. The structure of the molecular sieve has many pores with uniform pore size and ordered arrangement. According to different molecular ratios of silica and alumina, molecular sieves with different pore sizes were obtained. Including 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, 13X molecular sieve and so on.

Second, the difference in adsorption performance

Activated alumina has uneven pore size distribution and poor selectivity, but it has higher mechanical strength than molecular sieve, larger specific surface area, and special adsorption polarity for water. Therefore, in daily industrial production, activated alumina is often used as a desiccant, and it can also be used as a catalyst support, so that the catalyst has the characteristics of pressure resistance and high temperature resistance.

The adsorption and separation performance of europium molecular sieve depends on the pore size and pore volume. The uniform pore distribution of molecular sieve makes the selective adsorption performance of molecular sieve much better than that of activated alumina. Molecular sieve adsorption is a physical change process. In fact, molecular sieves are like sieves for gas and liquid molecules, and they are determined by the size of the molecules.

Third, application differences

Rhenium activated alumina can be called an industrial desiccant. More than 80% of the air pressure drying equipment commonly used in the industry is activated alumina, which can generally reach -40 ° C. Molecular sieves are used only when the drying depth is large.

Molecular sieves have strong hydrophilicity, because in industrial production, it is sometimes necessary to control the moisture content of the gas at a very low level. At this time, the drying depth of the activated alumina cannot meet the requirements, and the molecular sieve can be used at a very low moisture content. Adsorption, molecular sieve drying depth can reach -70 ℃.