MnOx supported on carbon nanotubes by different methods for the SCR of NO with NH3

Abstract

In order to modify the catalytic properties of MnOx via confinement within the channels of carbon nanotubes (CNTs), a series of MnOx catalysts supported by CNTs were prepared by different methods, in which MnOx was introduced on the outside surface only or on the inside and outside surface of CNTs. The catalysts showed different activity in SCR of NOx with NH3 in the temperature range of 80–300°C. The catalyst in which some MnOx was introduced into CNT channels exhibited higher NOx conversion than that in which all the MnOx was on the outside surface of CNTs. From the result of the activity test, it was indicated that the internal diffusion of molecules may not be the key influencing factor on the catalytic activity when the particle diameter was very smaller comparing with the tubes. In addition, the result of characterization showed that MnOx confined in the channels had better abilities of supplying oxygen and adsorbing NO which played an important role in the NH3-SCR, and it can partially be attributed to the electronic interaction between MnOx and the inner surface of nanotubes.