Waste straw derived Mn-doped carbon/mesoporous silica catalyst for enhanced low-temperature SCR of NO

• Published in: Waste management (Elmsford) 2021-12, Vol.136, p.28-35
• Main Authors: Gong, Zheng, Wang, Bangda, Chen, Wenhua, Ma, Shenggui, Jiang, Wenju, Jiang, Xia
• Format: Article
• Language: English
• Subjects: acidity; Activated carbon; catalysts; catalytic activity; Denitration; Low-temperature NH3-SCR; Mesoporous silica; nanoparticles; oxygen; porous media; silica; silicon; straw; Straw waste treatment; waste management
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2021.09.035

[Display omitted] •Carbon/mesoporous silica composite was successfully prepared from waste straw.•The composite catalyst has much higher NO conversion rate.•The acidity and redox properties of the composite catalyst were greatly improved. This work proposed a new strategy for the high value utilization of waste straw, in which a Mn-doped carbon/mesoporous silica composite catalyst was prepared by simultaneous utilization of carbon and silicon source from straw for low-temperature denitration. The results showed that the NO conversion rate reached 93% at 180℃ for the composite catalyst with Si/C mass ratio of 35% (Mn/ACMS (35%)). This was significantly higher than those of the activated carbon catalyst (Mn/AC) and mesoporous silica catalyst (Mn/MS), i.e., 58% and 50%, respectively. The SEM images showed that mesoporous silica nanoparticles were dispersed evenly on the carbon surface to form composite materials. XPS results indicated that Mn/ACMS (35%) catalyst showed higher content of chemically adsorbed oxygen (Oα) and Mn4+ (54.67% and 46.81%) than Mn/AC catalyst (34.38% and 17.49%) and Mn/MS catalyst (32.71% and 30.18%), which was responsible for the improved catalytic activity. Moreover, NH3-TPD results revealed that Mn/ACMS (35%) had high surface acidity of 6.47 mmol·g−1, significantly higher than Mn/AC catalyst of 1.51 mmol·g−1, which was beneficial for adsorbing NH3. H2-TPR results suggested that Mn/ACMS (35%) catalyst had much higher H2 consumption of 1.32 mmol·g−1 than Mn/AC and Mn/MS catalyst, suggesting better redox performance. The results demonstrated that the straw derived Mn-doped carbon/mesoporous silica composite catalyst can be a potential material for low-temperature denitration.