NO{sub 2} and NO adsorption properties of KOH-treated {gamma}-alumina
- Univ. of Florida, Gainesville, FL (United States)
A method to control nitrogen oxide (NO{sub x}) emissions from combustion sources by adsorption of NO{sub 2} and NO on {gamma}-alumina before and after KOH treatments has been evaluated. Compared to previously studied sorbents consisting of magnesium-oxide-coated vermiculite, untreated {gamma}-alumina exhibits a 6-fold increase in activity in tubular flow system tests. XPS analyses of the adsorbent surfaces before and after exposure to NO{sub x} indicate that potassium influences the NO{sub x}-sorption process. Subsequent treatment of {gamma}-alumina with KOH by impregnation or precipitation improves the adsorptive properties of {gamma}-alumina toward both NO{sub 2} and NO, with the precipitated samples performing better than impregnated samples. This research confirms previous findings that sorption of 3 mol of NO{sub 2} on {gamma}-alumina results in the catalytic formation of 1 mol of NO. However, treatment with KOH delays and reduces the formation of NO while increasing 5-fold the amount of NO{sub 2} adsorbed. Formation of nitrate and nitrite species is observed by XPS analysis of KOH-precipitated {gamma}-alumina exposed to NO{sub x}. A 40% loss of BET surface area occurs due to KOH precipitation on {gamma}-alumina followed by a further 56% loss in surface area after saturation with NO{sub x}. The addition of water vapor (3 vol %) to the feed gas stream significantly enhances the adsorption properties of the KOH-treated {gamma}-alumina. Washing the {gamma}-alumina pellets exposed to NO{sub x} with water essentially removes all of the potassium nitrates and nitrites formed. This harmless solution can be disposed of safely or used as fertilizer, and the pellets can be regenerated.
- OSTI ID:
- 659062
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 37, Issue 8; Other Information: PBD: Aug 1998
- Country of Publication:
- United States
- Language:
- English
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