Alkali Metal Deactivation on the Low Temperature Selective
Catalytic Reduction of NO<sub><i>x</i></sub> with NH<sub>3</sub> over MnO<sub><i>x</i></sub>‑CeO<sub>2</sub>: A Mechanism Study
Shangchao Xiong
Jingxia Weng
Yong Liao
Bo Li
Sijie Zou
Yang Geng
Xin Xiao
Nan Huang
Shijian Yang
10.1021/acs.jpcc.6b05175.s001
https://acs.figshare.com/articles/journal_contribution/Alkali_Metal_Deactivation_on_the_Low_Temperature_Selective_Catalytic_Reduction_of_NO_sub_i_x_i_sub_with_NH_sub_3_sub_over_MnO_sub_i_x_i_sub_CeO_sub_2_sub_A_Mechanism_Study/3484061
The
application of MnO<sub><i>x</i></sub>-CeO<sub>2</sub> as
the low temperature selective catalytic reduction (SCR) catalyst
to control NO<sub><i>x</i></sub> emission from coal-fired
power plants is extremely restricted due to the unrecoverable deactivation
by SO<sub>2</sub>. There is little SO<sub>2</sub> in the flue gas
from biomass-fired power plants, and the concentration of alkali metals
in the flue gas after the electrostatic precipitator is very low,
so the application of MnO<sub><i>x</i></sub>-CeO<sub>2</sub> may be possible to control NO<sub><i>x</i></sub> emission
from biomass-fired power plants. However, a very small amount of alkali
metals showed a seriously negative effect on NO reduction over MnO<sub><i>x</i></sub>-CeO<sub>2</sub> such that both NO<sub><i>x</i></sub> conversion and N<sub>2</sub> selectivity obviously
decreased. In this work, the mechanism of NO reduction over MnO<sub><i>x</i></sub>-CeO<sub>2</sub> and K-MnO<sub><i>x</i></sub>-CeO<sub>2</sub> was investigated by the transient reaction
study and the kinetic parameters of NO reduction were obtained from
the steady-state kinetic study. After comparison of the kinetic parameters,
the mechanism of potassium deactivation on NO reduction over MnO<sub><i>x</i></sub>-CeO<sub>2</sub> was discovered. The decrease
of the SCR activity of MnO<sub><i>x</i></sub>-CeO<sub>2</sub> after potassium deactivation was mainly attributed to the decrease
of acid site and Mn<sup>4+</sup> concentration on the surface, and
the increase of N<sub>2</sub>O selectivity was mainly related to the
occurrence of N<sub>2</sub>O formation over K-MnO<sub><i>x</i></sub>-CeO<sub>2</sub> through the Langmuir–Hinshelwood mechanism.
2016-07-01 00:00:00
Alkali Metal Deactivation
potassium deactivation
NH
N 2 O formation
CeO 2
x emission
alkali metals
SCR
N 2 selectivity
MnO x
N 2 O selectivity
flue gas