A rare earth ultra-stable Y-type molecular sieve and its preparation method

Abstract

The invention relates to a high-dispersion rare-earth ultrastable Y-type molecular sieve and a preparation method thereof, and in particular to a modified molecular sieve for preparation of a catalytic cracking catalyst and a preparation method thereof. Since the NaY molecular sieve in the invention is pretreated, the physical and chemical properties such as degree of crystallinity, dispersibility and stability of the zeolite NaY can be improved significantly. Compared with the ultrastable molecular sieve with the same rare earth content prepared by a conventional method, the rare-earth ultrastable Y-type molecular sieve prepared by the two exchange and two calcination method disclosed by the invention has the characteristics of low rare earth content, good dispersibility and stability, low coke yield and strong heavy oil conversion ability; and the has the process is simple, low in cost and pollution-free.

Description

technical field [0001] The invention relates to a highly dispersed rare earth ultra-stable Y-type molecular sieve and a preparation method thereof, in particular to a modified molecular sieve used for preparing catalytic cracking (FCC) catalysts and a preparation method thereof. Background technique [0002] Rare earth Y-type molecular sieve is one of the main active components of FCC catalysts. Its precursor is NaY molecular sieve, and its physical and chemical properties significantly affect the catalytic characteristics of the active component. [0003] The hydrothermal synthesis process of the precursor NaY molecular sieve is a very complicated process. The NaY molecular sieve crystallization system contains not only small NaY molecular sieve crystal particles, but also inorganic salt ions, as well as a large number of sols and gels. After the hydrothermal crystallization of NaY molecular sieve is completed, the inorganic salt ions and colloids in the molecular sieve ar...

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Problems solved by technology

The preparation process of the molecular sieve is complicated, the cost is high, and the raw materials have certain toxic effects on the human body and the environment

[0012] Chinese patent CN1629258 discloses a preparation method of a rare earth ultra-stable Y-type molecular sieve. In this method, NaY molecular sieve and an aqueous solution containing 6-94 wt% ammonium salt are subjected to conditions of normal pressure and a temperature greater than 90°C to not greater than the boiling point of the ammonium salt aqueous solution. Next, according to the weight ratio of ammonium salt and molecular sieve 0.1 to 24, contact twice or more to make the Na in the molecular sieve 2 The O content is reduced to below 1.5wt%, and then an aqueous solution with a rare earth salt content of 2 to 10wt% is used to contact the molecular sieve at 70°C to 95°C, so that the rare earth content in the molecular sieve is 0.5 to 18wt% (in RE 2 o 3 In the preparation process of the molecular sieve, multiple ammonium salt exchanges are required, the preparation process is cumbersome, the ammonia nitrogen pollution is serious, and the cost is high

[0014] From the point of view of the prior art, since the NaY molecular sieve crystallization slurry prepared by the hydrothermal method contains a large amount of unreacted amorphous colloids, the colloids cannot be effectively removed in the subsequent separation process, resulting in the low crystallinity of the prepared NaY molecular sieves. Poor stability and dispersibility

In the existing molecular sieve exchange process, there is a competitive exchange between rare earth ions and ammonium ions, the utilization efficiency of rare earth ions is low, the crystallinity of molecular sieves is low, and the retention rate is poor

The preparation process of rare earth Y-type molecular sieve is complicated, the cost is high, and it is mostly synthesized from environmentally polluting raw materials, which has adverse effects on the environment and human body, and the existing methods do not have the function of improving the dispersion of molecular sieves

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