Patent ID: 8377413

Claim:
A method for preparing a mayenite-containing oxide, which comprises a firing step of heating a starting material containing at least one compound selected from the group consisting of a calcium aluminate, calcium oxide, aluminum oxide, a calcium compound which becomes calcium oxide by firing and an aluminum compound which becomes aluminum oxide by firing, and containing Ca atoms and Al atoms in a ratio such that, by molar ratio based on CaO and Al 2 O 3 , CaO:Al 2 O 3 is from 9:10 to 14:5, at a temperature of from 900 to 1,250° C. to obtain a fired powder, and a hydrogenation step of firing the fired powder at a temperature of at least 1,210° C. and lower than 1,350° C. in a hydrogen-containing gas having an oxygen partial pressure of at most 1,000 Pa to obtain a mayenite-containing oxide and having a hydride ion density of at least 1×10 18 /cm 3 .