Ultra-stable rare earth Y-type molecular sieve and preparation method thereof

Abstract

The invention provides an ultra-stable rare earth Y-type molecular sieve and a preparation method thereof. According to the method, a NaY molecular sieve is used as a raw material, then a rare earth exchange reaction and a dispersion pre-exchange reaction are carried out, and finally, ultra-stable roasting is carried out. The molecular sieve contains 1 to 20 wt% of rare earth oxide and no more than 1.2 wt% of sodium oxide, has a degree of crystallization of 51 to 69% and a cell parameter of 2.451 to 2.469 nm. Compared with the prior art, a rare earth ion of the molecular sieve prepared by using the method is positioned in a sodalite cage, which is embodied by no loss of the rare earth ion in the process of reverse exchange; meanwhile, the molecular sieve prepared by using the method has a particle size D (v, 0.5) of no more than 3.0 mu m and a particle size D (v, 0.9) of no more than 20 mu m. The molecular sieve is used as an active component of a catalytic cracking catalyst and has the characteristics of high heavy oil conversion capability and high yield of a high-value target product.

Description

technical field [0001] The invention relates to an ultra-stable rare earth Y-type molecular sieve and a preparation method thereof, in particular to an ultra-stable rare earth Y-type molecular sieve with improved cracking activity and particle dispersibility and a preparation method. technical background [0002] Catalytic cracking unit is an important secondary processing method for crude oil, and its comprehensive product distribution determines the economic benefits of the refinery. In recent years, with the intensification of the trend of heavy crude oil, FCC catalysts are required to have stronger heavy oil conversion capacity and high-value product selection. sex. As the main provider of the cracking activity of heavy oil cracking catalysts, Y-type molecular sieves with high cracking activity and high activity stability have always been the core technical subject of research in the field of catalysis. [0003] On how to improve the cracking activity and activity stabi...

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Problems solved by technology

In the modification method involved in this patent, a solution containing ammonium ions needs to be added, the purpose of which is to reduce the sodium oxide content in the molecular sieve or reduce the damage to the molecular sieve structure by acid gas during the roasting process, but this technology has the following technical defects: 1) preparation A large amount of ammonium ions are added during the process, and ammonium ions eventually enter the atmosphere or sewage, increasing ammonia nitrogen pollution and pollution control costs; 2) This patented method cannot effectively solve the problem of molecular sieve particle agglomeration, which reduces the specific surface and pore volume of molecular sieves , increasing the pore resistance of the molecular sieve exchange process, making it difficult to accurately locate and quantify the modified elements in the molecular sieve cage; Rare earth ions are introduced by means of ion exchange. During the exchange process, there is a competitive reaction between ammonium ions and rare earth ions. Ammonium ions will preferentially occupy the positions of rare earth ions, which increases the resistance of rare earth ions to enter the molecular sieve cage and reduces the resistance of rare earth ions. Utilization

In this technology, the rare earth modification uses the "cross-baking" product as the raw material for the second exchange modification. After the molecular sieve undergoes "cross-baking", the unit cell shrinks, and the aluminum fragments inside the channels block the channels, increasing the rare earth ions. Exchange resistance, making it difficult for rare earth ions to locate accurately in the sodalite cage

[0009] The Y-type molecular sieve modification methods provided by the above patents do not specify the precise positioning of rare earth ions, resulting in the activity stability and structural stability of the Y-type molecular sieve prepared by the prior art cannot adapt to the heavy and inferior raw material oil development trend

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