Mercury emission
is an important issue during chemical looping
combustion (CLC) of coal. The aim of this work is to explore the effects
of different flue gas components (e.g., HCl, NO, SO
2
, and
CO
2
) on mercury transformation in the flue gas cooling
process. A two-stage simulation method is used to reveal the reaction
mechanism of these gases affecting elemental mercury (Hg
0
) oxidation. Furthermore, using this method, Hg
0
oxidation
by eight oxygen carriers (Co
3
O
4
, CaSO
4
, CeO
2
, Fe
2
O
3
, Al
2
O
3
, Mn
2
O
3
, SiO
2
, and CuO) commonly
used in CLC are investigated and their Hg
0
oxidation efficiencies
were compared with the existing experimental results. The results
show that HCl, NO, and CO
2
promote Hg
0
oxidation
during flue gas cooling, while SO
2
inhibits Hg
0
oxidation. The stronger the oxygen release capacity of oxygen carriers,
the higher the oxidation efficiency of Hg
0
becomes. The
order of Hg
0
removal efficiency from high to low is Co
3
O
4
, CuO, Mn
2
O
3
, CaSO
4
, Fe
2
O
3
, CeO
2
, Al
2
O
3
, and SiO
2
, and this sequence is in good
agreement with the existing experimental results. Different flue gas
components directly or indirectly affect the O
2
content,
thus affecting the content of gaseous oxidized mercury (Hg
2+
). Different oxygen carriers have different oxygen release capacities
and different Hg
0
oxidation efficiencies. Therefore, O
2
is the core species affecting the mercury transformation
in CLC.
