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

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 180celcius 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 (O-alpha) 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. H-2-TPR results suggested that Mn/ACMS (35%) catalyst had much higher H-2 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.

Automated summary

The study introduced a new strategy for the high value utilization of waste straw by preparing a Mn-doped carbon/mesoporous silica composite catalyst, which demonstrated high catalytic activity and redox performance for low-temperature denitration. The results showed significant improvements in NO conversion rate, surface acidity, and H-2 consumption compared to traditional activated carbon and mesoporous silica catalysts.