The invention relates to a Fe
molecular sieve composite catalyst, which comprises an
active component Fe, a catalyst carrier Beta and a
mordenite. A preparation method comprises the following steps of: 1, performing
ion exchange on a Si / Al H-Beta
molecular sieve and FeCl2; 2, removing Cl ions in the solution, and
drying the obtained
filter cake and
roasting the
filter cake in a
muffle furnace to obtain the Fe / Beta
molecular sieve catalyst; 3, placing the Fe / Beta molecular
sieve catalyst in the water, adding the
mordenite, and
roasting the mixture to obtain the Fe / Beta / Mor molecular
sieve composite catalyst; 4, dissolving the Fe / Beta / Mor molecular
sieve into the de-ionized water, and adding concentrated
nitric acid to obtain
coating serum; and 5, dipping a
Cordierite honeycomb ceramic carrier in the serum, blowing a residual liquid, and after
drying the mixture in the shade,
drying and
roasting the mixture. The catalyst can efficiently purify
NOx in the
tail gas of a diesel vehicle, a lean-burning
gasoline car and a lean-burning
natural gas vehicle, and has the characteristics of environment protection and highly efficient catalytic activity.