Sb-loaded MnOx/TiO2/CNTs catalysts for selective catalytic reduction of NOx: insight to the SO2 and H2O tolerance

Abstract

Purpose

This paper aims to synthesize and test Mn-Sb/TiO₂-CNT catalysts with different Sb/Mn molar ratios to be used in NH₃-SCR reaction.

Design/methodology/approach

A series of Sb-loaded carbon nanotubes (CNTs)-based Mn/TiO₂ catalysts were prepared by the incipient wetness co-impregnation method and tested for the selective catalytic reduction (SCR) of NOx with NH₃.

Findings

The Sb-loaded Mn/TiO₂-CNTs catalyst outperformed other catalysts and presented the highest activity in the temperature regime of 100–400°C. The catalyst loaded with Sb also showed good SO₂ and H₂O resistance and exhibited better thermal stability. A stepwise study of SO₂ addition evidenced that Mn-Sb/TiO₂-CNTs catalyst exhibited better SO₂ resistance than the base catalyst Mn/TiO₂, where the Sb doping greatly inhibited the sulphating of active phase of the catalyst.

Originality/value

In Sb-loaded catalysts, the formed SOx species fused with SbOx instead of MnOx. This favoured interaction of SO₂ with SbOx successfully prevents the MnOx from being sulphated by SO₂ which substantially improves the SO₂ tolerance of Sb-loaded catalysts.