The invention relates to a preparation method of a catalyst, and concretely relates to a preparation method of a porous rod-shaped
spinel structured catalyst. The preparation method comprises the following steps: respectively preparing an A
type metal salt solution and a B
type metal salt solution by using deionized water; measuring the above two solutions, and uniformly mixing the two solutions under magnetic stirring to obtain a clarified dark blue solution; gradually adding an NH4(OH) solution to the above obtained
mixed solution, and adding
cetyltrimethylammonium chloride to water to form gel; preparing an
aqueous solution of hydrazine
hydrate, continuously heating the above stirred
mixed solution, and cooling the heated
mixed solution to
room temperature in order to obtain a green fluffy
solid product; washing the
solid product with deionized water and
anhydrous ethanol multiple times, and
drying the washed
solid product to obtain solid
powder; and transferring the solid
powder to a
quartz reactor, and heating and calcining the solid
powder to obtain fluffy powder. The catalyst solves the technical problem of unsatisfactory purification of PM in diesel car
tail gas.