Mechanism Study on Heterogeneous Fenton Catalytic Oxidation of NO Using PrGO as the Carrier

Abstract

In practical industry, the challenge of removing nitric oxide (NO) from flue gas at temperatures below 200°C persists. The heterogeneous Fenton reaction catalytic oxidation of NO offers an effective approach for achieving denitrification of flue gas at these low temperatures. Utilizing graphene oxide (GO) as the carrier, the Fenton catalyst demonstrates superior catalytic efficiency by effectively facilitating the reduction of Fe(III). Principle analysis shows that reducing GO and using partially reduced graphene oxide (PrGO) as a carrier can further improve catalytic efficiency and stability. Thus, the experimental and theoretical investigation of the mechanism of heterogeneous Fenton catalytic oxidation of NO using PrGO as the carrier is performed in detail in this paper. Experimental studies reveal that the partial reduction of GO significantly enhances catalytic efficiency, leading to an approximate 10% increase in denitrification efficiency at temperatures below 200°C. Furthermore, the catalytic activity of PrGO is observed to rise with increasing reduction degree. Quantum chemical calculations support these findings, showing that the heterogeneous Fenton reaction barrier on PrGO support lacking other oxygen-containing functional groups is significantly lower (34.1 kJ/mol) than that on PrGO support with epoxy, hydroxyl, and carboxy group (75–95 kJ/mol). This confirms the experimental results and underscores the effective enhancement of catalytic activity through GO reduction. Additional investigation employing natural hybrid orbit (NBO) analysis reveals that an increase in oxygen-containing functional groups leads to a decrease in the number of sp2 hybrid carbon atoms in the graphite ring, while the proportion of sp3 hybrid C─ O bonds increases. This disrupts the conjugated structure of the graphite ring, reduces electron mobility, and consequently decreases the conversion rate from ferrous iron to ferric iron, thereby reducing catalytic efficiency. The present study holds significant implications for advancing the development of heterogeneous Fenton reactions for the removal of flue gas pollutants.