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.