Pseudo-boehmite (PB) is the first crystal phase formed in the synthesis of aluminum hydroxide. The crystal phase is the same as the boehmite, but the crystal is incomplete and often exists in a colloidal state, so it is also called colloidal boehmite. The pseudo-boehmite is widely used as a carrier for catalytic cracking catalyst , and can function as an active matrix and a binder. The amount of addition and peptization directly affect the activity of the catalyst, pore volume and pore size distribution, wear index and other important indicators.
There are various preparation methods of pseudoboehmite. According to the source of the raw materials and the nature of the product, the gibbsite quick-release method, the aluminum alkoxide method, the aluminum salt neutralization method and the carbonization method can be divided . In China, the aluminum salt carbonization method is mainly used, that is, the CO2 is introduced into the NaAlO2 solution for precipitation, and the pseudo-boehmite of different crystal forms can be obtained by controlling different gelation temperatures and washing temperatures. At present, domestic heavy oil cracking catalysts generally use double aluminum-based binders, namely alumina sol and acidified pseudo-boehmite. The acidified pseudoboehmite as a catalyst for the preparation of a binder has the advantage of strong heavy oil cracking ability .
At present, the pseudo-boehmite used by a catalyst company often exhibits a large fluctuation in peptization performance, which is manifested by the fact that some batches of pseudo-boehmite have a large acid consumption during the peptization process, and the prepared catalyst has poor strength. . In order to find out the reason for the large difference in peptization performance, it is necessary to analyze its physical properties and correlate with peptization properties to establish new indicators to distinguish pseudo-boehmite with different peptization properties.