Studies on the Surface Chemistry Based on Competitive Adsorption of NO_x-SO₂ onto a KOH Impregnated Activated Carbon in Excess O₂

Abstract

This study identifies surface chemistry characteristics based on competitive behavior in the simultaneous adsorption behavior of NOx (NO rich) and SO2 using KOH impregnated activated carbon (K-IAC) in excess O2. The NOx and SO2 adsorption on K-IAC occurred mainly through the acid-base reaction. The high surface area with many pores of activated carbon acted as storage places of oxide crystal produced from NOx and SO2 adsorption. KOH, an impregnant, provided the selective adsorption sites to NOx and SO2, enabling simultaneous adsorption. However, larger amounts of SO2, with higher adsorption affinity to K-IAC compared to NOx, were adsorbed in a NOx/SO2 coexistent atmosphere. Oxygen was chemisorbed to K-IAC, which enhanced the selective adsorptivity for NO. In binary-component adsorption of NOx and SO2 on K-IAC, oxide crystals such as KNO, (x = 2,3) and K2SOx (x = 3,4) were dominantly formed through two different adsorption mechanisms by chemical reacton. Depending on the extent that oxide crystals blocked pores, compositions of oxide crystals were distributed differently according to depth.

Effect of Coal Blending Methods with Different Excess Oxygen on Unburned Carbon and NOx Emissions in an Entrained Flow Reactor

“…The heterogeneous mechanisms of the catalytic effect that can be incorporated in numerical modeling are as follows: − First, NO is absorbed at the active sites of the char surface; the metal ions remove the O atom from the NO molecule, resulting in the formation of metal oxide and an N radical. The metal oxides are subsequently reduced into metal ions by the char.…”

Effects of Surface Features on Sulfur Dioxide Adsorption on Calcined NiAl Hydrotalcite-like Compounds

“…Many new strategies have been proposed. − However, the most popular and inexpensive method for SO 2 removal is the addition of selective sorbents with the fuel . The sorbents used frequently mainly include activated carbons, activated carbon fibers, and fly ash . SO 2 could be retained via physical adsorption in their small pores.…”

Interactions of NO2 with activated carbons modified with cerium, lanthanum and sodium chlorides

“…Those surface complexes, existing mainly on the outer surface can be considered as temporary entities leading to further chemical transformations or as new functional groups, depending on their stability and environmental conditions. To increase the adsorption efficiency via surface reactions, carbon can be impregnated with various species such as KOH [21,22], which react with NO 2 forming nitrates, or transition metals, such as copper, on which reduction could occur [10,12,[23][24][25]. These kinds of modifications follow the studies on inorganic materials, as, for example, on alumina, KOH impregnated alumina, MgO, Fe 2 O 3 or TiO 2 , which showed that chemisorption via nitrite and nitrate formation is the main adsorption/reactive adsorption mechanism on their surfaces [26].…”