Figure 5 . (a) Illustration of desulfurization process of
sorbent Zn@MnOx /PCNFs. (b) Breakthrough curves,
(c) sulfur capacities of sorbents MnOx /CNFs,
MnOx /0PCNFs, MnOx /24PCNFs
and Zn@MnOx /24PCNFs. (d) Utilization rates of
active components of sorbents MnOx /24PCNFs and
Zn@MnOx /24PCNFs.
Based on the above analyses, the process of H2S removal
upon sorbents MnOx /24PCNFs and
Zn@MnOx /24PCNFs was proposed as the reactions and
illustration graph displayed (Figure. 5a) .
2MnO2 + H2S → 2MnO + H2O
+ SO2 (1)
3Mn3O4 + H2S → 9MnO +
H2O + SO2 (2)
MnO + H2S → MnS + H2O (3)
MnO2 + 2H2S → MnS2 +
H2O (4)
ZnO + H2S → ZnS +
H2O (5)
ZnMnO3 + 2H2S + H2 → ZnS
+ MnS + 3H2O (6)
The desulfurization performance of MnOx /CNFs,
MnOx /XPCNFs and
ZnY@MnOx /24PCNFs sorbents was also tested to
uncover the influential factors behind the sorbent performance (Figure.
5b). Figure. S18a and b showed the breakthrough curves and the total
sulfur capacities at the detection point of 900 ppm. The breakthrough
sulfur capacities of various sorbents were ranked in the following
order: Zn3@MnOx /24PCNF >
Zn2@MnOx /24PCNF >
Zn@MnOx /24PCNF >
MnOx /32PCNFs >
MnOx /24PCNFs >
MnOx /16PCNFs >
Zn0@MnOx /24PCNFs >
MnOx /8PCNFs >
MnOx /CNFs >
MnOx /0PCNFs, which was consistent with the
content order of active components in different sorbents. As shown in
Figure. 5b and c, the breakthrough sulfur capacity of
MnOx /24PCNFs sorbent (6.51 g S 100
g-1 sorbent) was 2.3 and 2.8 times higher than that of
the sorbents MnOx /CNFs and
MnOx /0PCNFs, respectively, which was also in the
same trend with the content of Mn2+ loaded on the
corresponding sorbents. This phenomenon is mainly attributed to the
different structure types of the sorbents, of which the effect of
massive micro-pores within supporter 0PCNFs exceeded that of its high
specific surface area. In contrast, the meso- and macro-pores within
supporter 24PCNFs contributed greatly to the improvements in loading
content and desulfurization performance of the sorbent
MnOx /24PCNFs.
After the ZnO nanoparticles anchored on
MnOx /24PCNFs via hydrothermal reaction, the
sulfur capacity of sorbents ZnY@MnOx /24PCNFs all
increased. Although the sulfur capacity of
Zn2@MnOx /24PCNFs and
Zn3@MnOx /24PCNFs was higher than that of
Zn@MnOx /24PCNFs (9.63 g S 100
g-1 sorbent), but their utilization rates of active
components were far behind due to ZnO nanowires were not fully
participated in desulfurization. More important, the total utilization
of active components increased from 46% of
MnOx /24PCNFs to 73% of
Zn@MnOx /24PCNFs (Figure. 5d). These results
indicate that the introduction of ZnO not only increased the sulfur
capacity, but also improves the total utilization of active components.
Among them, the utilization of ZnO was up to 117%, owing the uniform
dispersion of ZnO on the surface of MnOx /24PCNFs.