Novel Low-Cost Simultaneous Removal of NO and SO₂ with ·OH from Decomposition of H₂O₂ Catalyzed by Alkali-Magnetic Modified Fly Ash

Abstract

An iron-based catalyst with excellent performance and low price was used for simultaneous removal of SO2 and NO x in a typical Fenton system. The catalyst was developed from fly ash of pulverized coal furnace by alkali-magnetic modification process. In other words, the raw fly ash was first modified by Ca­(OH)2, which destroyed the vitreous shell and made the internal substances such as Al2O3, SiO2, and Fe2O3 dissolve out gradually, and then separated magnetically and roasted, and the high magnetic Fe2O3 content of high reactivity was obtained. In the fixed bed experimental system, an ultrasonic nebulizer was adopted to atomize hydrogen peroxide which can reduce the particle size of hydrogen peroxide and shorten the gasification time greatly. Effects of the concentration of hydrogen peroxide, reaction temperature, iron oxide content, and initial concentration of SO2 and NO x on the collaborative removal efficiencies were investigated. Under low hydrogen peroxide concentration (1 mol/L) and flow rate (0.03 mL/min), 100% desulfurization efficiency and 90% denitrification efficiency can be achieved using hydrogen peroxide catalyzed by the modified fly ash. The catalytic mechanism and reaction mechanism were analyzed by XRF, XRD, ESR, SEM, BET, and XPS.

Partial Oxidation of NO by H2O2 and afterward Reduction by NH3-Selective Catalytic Reduction: An Efficient Method for NO Removal

“…It is clearly found that the NO conversion was noticeably enhanced with the increasing molar ratio of H 2 O 2 /NO. In addition, the NO conversion drops with the increasing temperature, which is attributed to the faster consumption of the generated active OH radicals by reacting with each other at higher temperatures. − Nevertheless, H 2 O 2 can efficiently oxidize NO to NO 2 in low temperatures (200–280 °C), which is promising to enhance the SCR reaction at low temperatures. For efficient removal of NO x , the NO oxidation rate should be controlled below 50% because the reaction of excessive NO 2 with NH 3 is significantly slow when NO is absent .…”

Modified Fe-Rich Palygorskite as an Efficient and Low-Cost Heterogeneous Fenton Catalyst for NOx and SO2 Removal

“…As for L-ATP1, the removal efficiency was as high as 88.6%. The results indicated that the NO x removal efficiency can be greatly improved by increasing Fe content because H 2 O 2 can be catalyzed by FeOx to generate strong oxidizing radicals such as hydroxyl radicals ( • OH) and superoxide anions ( • OOH), which could oxidize NO to more soluble NO 2 or HNO 2 . − However, when the catalyst was L-ATP2, the removal efficiency slightly decreased to 81.9%. According to BET results (Table S3), with further increasing the Fe content, the porosity and specific surface area of ATP decreased, which result in the destruction of the pore structure .…”

Green and Moderate Activation of Coal Fly Ash and Its Application in Selective Catalytic Reduction of NO with NH3

“…Zhang et al presented a feasible method to synthesize the Mn–Fe/bentonite-CFA SCR catalyst, in which the ideal mass ratio of bentonite to CFA was established as 4:1, and 6% of starch was added as the pore-forming materials. Yang et al stated that the integration of Ca­(OH) 2 and magnetic modification could be used to destroy the molten shell over the CFAs, which favored the dissolution of internal substances and improved the molding capacity of CFA-based carriers. In comparison with other additives, titanium dioxide was superior in its large specific surface area and abundant acid sites .…”