Conversion of CaTi1–xMnxO3–δ-Based Photocatalyst for Photocatalytic Reduction of NO via Structure-Reforming of Ti-Bearing Blast Furnace Slag

摘要

In this work, a novel low-cost and robust approach is developed to covert Ti-bearing blast furnace slag (Ti-slag) to the main feed stock of photoassisted NH_(3) selective catalytic reduction (Photo NH_(3)-SCR) of NO with high performance. The CaTi_(1–x )Mn_(x )O_(3?δ) catalyst was directly extracted from the Ti-bearing slag with MnO_(2) in situ modification and Na_(2)CO_(3) reformation followed by dilute hydrochloric acid leaching and water washing. Various methods were employed to characterize the structure changes of the slag in the preparation processes of MnO_(2) in situ doping, Na_(2)CO_(3) reforming, and leaching. Mn element can be incorporated into the perovskite CaTiO_(3) with 0.16 to 1.79 wt % depending on the amount of MnO_(2) added in Ti-slag at 1500 °C. It is interesting to note that the amount of Mn incorporated into the perovskite decreases remarkably with increasing the additional amount of MnO_(2) in the in situ doped modification, which reaches a maximum of 9.54 wt % for the reformed slag of 5 wt % MnO_(2) addition. Moreover, most of the Si has been transferred to the sodium aluminum oxide instead of diopside, which is easily removed in the following leaching stage. Further semiquant crystalline analysis shows that there is 99 wt % of perovsvkite CaTi_(1–x )Mn_(x )O_(3?δ) with 1 wt % hexamagnesium manganese(IV) oxide in the slag after leaching with 5 wt % MnO_(2) addition, and the catalyst shows more than 93% NO removal efficiency at 300 °C in photoassisted NH_(3)-SCR performance. The present study proposes a new route for the high value-added recycling of silicate minerals and wastes via structure-reforming with in situ optimization of secondary resources.