The difference between pseudo-boehmite and boehmite

The difference between pseudo-boehmite and boehmite：

Pseudo-boehmite has the same molecular formula (AlOOH) as boehmite, and they are different crystal forms of alumina monohydrate. The reason why it is called pseudo-boehmite is because pseudo-boehmite is a kind of boehmite with incomplete crystals, they have very similar XRD patterns, the positions of the main diffraction peaks of the two are almost the same, the difference is Only the intensity of the diffraction peaks is different, so compared with pseudo-boehmite, boehmite is only larger in grain size, higher in crystallinity and more complete in crystallinity.

The research shows that there is no clear dividing line between the two, and it is usually more appropriate to use the average grain size as the main criterion to divide boehmite and pseudo-boehmite. The product with an average grain size of less than 10nm is regarded as pseudo-boehmite; the product larger than 50nm is regarded as boehmite; when it is 10-50nm, it is regarded as the intermediate product of boehmite and pseudo-boehmite, Intermediate products can also be classified as pseudo-boehmite.

In summary, the differences between the two are as follows:

(1) Pseudo-boehmite is an aggregation of amorphous substances with only weak diffraction peaks; boehmite has a good crystal structure and sharp diffraction peaks.

(2) Pseudo-boehmite has higher specific surface area and larger pore volume than boehmite. The specific surface area of pseudo-boehmite gradually decreased with the increase of temperature, and the specific surface area of boehmite first increased and then decreased with the increase of temperature.