The invention discloses an improved diesel hydrocracking catalyst and a preparing method thereof. Raw materials of the catalyst includes, by weight, 4-25% of
molecular sieve, 10-65% of gamma-Al2O3, 15-70% of
amorphous silica-
alumina, 9-40% of binder and 7-35% of active
metal oxide, the specific surface area of the catalyst is 220-450 m<2> / g, and the total pore volume is 0.30-0.73 cm<3> / g.
Molecular sieve with an template agent not removed is added in the process of preparing a
molecular sieve and aluminum
oxide composite material, NH4+ generated through aluminum salt and
ammonia water reaction exchanges with alkali Na+ for balancing negative charges of a
molecular sieve skeleton in a
mixed solution, the organic template agent and NH4+ in the molecular
sieve are simultaneously removed in the calcinations process,
ammonium exchange and template agent removal of the
zeolite molecular
sieve are completed in the process of preparing the
composite material, the step of individually conducting template agent removal and
ammonium exchange on the molecular
sieve, the template agent has the effects of supporting and protecting the molecular sieve pore structure, and the catalyst can obviously reduce the
condensation point of diesel fraction and increase the
cetane number of diesel on the premise of ensuring the high diesel yield.