Catalysts for the reduction of nitrogen oxides

摘要

A zeolite-supported catalyst, for selective NOx redn. by hydrocarbons, contains Ga and Ag (pref. in amounts 0.1-10 wt.%), the zeolite having a Si/Al atomic ratio of greater than 2, pref. greater than 4. Also claimed are (i) prepn. of the above catalyst, in which the zeolite is treated with a Ga-contg. soln. and with an Ag-contg. soln. to achieve impregnation or exchange; and (ii) a process for NOx redn., in the presence of the above catalyst, involving selective redn. of the NOx content of a gas mixt. by hydrocarbons at 100-600 degrees C..