Preparation of hydrocracking catalyst

Hydrocracking catalyst is composed of hydrogenated metal components and acidic carrier, carrier is generally amorphous aluminum silicate, zeolite molecular sieve add amorphous aluminum silicate, zeolite molecular sieve add alumina.The preparation of hydrocracking catalyst consists of amorphous aluminum silicate and alumina, the addition of zeolite molecular sieve, the loading of hydrogenated metal components.

Preparation of amorphous aluminum silicate

The feedstock of amorphous aluminum silicate is aluminum chloride and sodium silicate solution, with ammonia water as precipitating agent. According to the adding method and order of the solution, it can be divided into three preparation processes: cogel method, silica sol method and step precipitation method.

The co-gumming method is to add dilute ammonia water to aluminum chloride solution at a certain speed under stirring. When pH=4, there is a thick point, stop feeding, continue stirring until it becomes a well-flowing slurry, add dilute water glass solution, adjust the pH value with ammonia water after adding, aging, washing, drying and calcination.

Silica sol method is to add sodium silicate solution to stirred nitric acid solution at a certain speed, so that pH＜2, make silica sol, add silica sol to aluminum chloride solution, make silica sol, then neutralize with ammonia water continuously into glue, aging washing, drying, calcination.

The multi-step precipitation method is to add dilute nitric acid at a certain speed in the stirred water glass, so that it is gelated in the alkaline, and continue to add acid to make part of the gelation, aging for a certain time, at the same time add aluminum chloride and ammonia water to precipitate aluminum on the silicon gel.It can also prepare aluminum solution or gel first, then add water glass to make silicon aluminum gel. In the preparation of aluminum silicate, it is essential to control the concentration, temperature and pH value at the time of precipitation.

The addition of zeolite molecular sieve can be added at the time of precipitation, can also be added to the slurry after precipitation, or mixed in the forming.