The influence of interaction between palladium and indium on the activity of Pd–In/Al 2O 3 catalysts in reduction of nitrates and nitrites

Abstract

The influence of indium addition on the catalytic properties of palladium catalysts supported on Al 2O 3 in the reaction of nitrates reduction to nitrogen was studied. It was found that indium did not show any activity by itself, but acted as a “promoter” for the catalytic activity of monometallic Pd/Al 2O 3 catalysts. The X-ray diffraction (XRD) and Time-of-flight secondary ion mass spectrometry (ToF-SIMS) studies proved the existence of intermetallic interactions between Pd and In, which probably modified activity and selectivity of bimetallic catalysts in this reaction. The ToF-SIMS technique showed the presence of intermetallic compounds in all the studied bimetallic systems, which could not be proved by XRD measurements in the case of the systems with a small amount of indium.