Patent ID: 11918987
Assignee: WANHUA CHEMICAL GROUP CO., LTD.
Field: Chemical engineering (Chemistry)
Classification: CPC B  C  Y | IPC B  C

Claim 2:
3. The preparation method according to claim 2, wherein in step (2), calcination process conditions are: a calcination atmosphere is ammonia gas, and a two-stage temperature programming is adopted, in which in a first stage, a calcination temperature is 140° C. to 160° C., a calcination duration is 1 to 3 h, and a space velocity of the ammonia gas is 2 to 5 h−1, and in a second stage, a calcination temperature is 450° C. to 600° C., a calcination duration is 3 to 5 h, and a space velocity of the ammonia gas is 0.4 to 2−1.