Small-grain NaY-type molecular sieve and preparation method thereof

Abstract

The invention discloses a small-grain NaY-type molecular sieve and a preparation method thereof. The small-grain aY-type molecular sieve has the following properties: the SiO2 / Al2O3 molar ratio is higher than 6.0 and no higher than 9.0; the grain average diameter is 200-700nm; the specific surface area is 800-1000m<2> / g; the pore volume is 0.30-0.45mL / g; the relative crystallinity degree is 90-130%; the lattice parameter is 2.460-2.470nm; the relative crystallinity degree after roasting for 3h under a temperature of 650 DEG C in air is higher than 90%; and the relative crystallinity degree after a water vapor hydrothermal treatment for 2h under a temperature of 700 DEG C is higher than 90%. The preparation method comprises the following steps: an amorphous silica-alumina precursor prepared with a specific carbonization method, a directing agent synthesized under low temperature, part of a silicon source, and the like are mixed under a low temperature, such that silica-alumina gel is prepared; and crystallization is carried out, such that the small-grain NaY-type molecular sieve is obtained. The small-grain NaY-type molecular sieve can be applied in a hydrocracking reaction, has has good cracking activity and product selectivity.

Description

technical field [0001] The invention relates to a Y-type molecular sieve and a preparation method thereof, in particular to a small-grain NaY-type molecular sieve and a preparation method thereof. Background technique [0002] Y-type molecular sieve is currently the most common cracking active component in the field of heavy oil cracking. The crystal grain is generally about 1000nm. After the reaction, the product is also difficult to diffuse out, so its cracking activity and selectivity of the target product are restricted. Compared with conventional Y-type molecular sieves, small-grain Y-type molecular sieves have a larger outer surface area and more active centers on the outer surface, which is conducive to improving the cracking capacity of macromolecular hydrocarbons, and thus has superior catalytic performance. At the same time, reducing the grain size of the Y-type molecular sieve can also improve the utilization rate of active sites on the inner surface. In general...

AI Technical Summary

Problems solved by technology

[0004] The method for preparing fine-grained Y-type molecular sieves proposed in CN1081425A is to precrystallize the NaY synthesis solution at 80°C to 180°C for 1 to 10 hours, then add the directing agent after cooling to room temperature, and then add the directing agent at 80°C to 100°C. Continue to crystallize for 5 to 25 hours, the process steps are more complicated and difficult to control, and the hydrothermal stability of the fine-grained Y-type molecular sieve obtained is poor

[0011] At present, during the preparation process of small-grain NaY molecular sieves in the existing method, silicon and aluminum are easily lost, the utilization rate of silicon is low, and the distribution of silicon and aluminum is not uniform, and agglomeration is easy to occur. Therefore, the existing method is still unable to prepare silicon-aluminum ratio. , and small crystal NaY molecular sieve with good thermal stability and hydrothermal stability

Images