Selective catalytic reduction by urea in a fluidized‐bed reactor

Abstract

The selective catalytic reduction (SCR) of NO x by urea as a reducing agent was carried out over fresh and sulfated CuO/γ -Al 2 O 3 catalysts in a fluidized-bed reactor. The optimum temperature ranges for NO reduction on the fresh and sulfated CuO/γ -Al 2 O 3 catalysts were 300-350• C and 400-450 • C, respectively. NO reduction with the sulfated CuO/γ -Al 2 O 3 catalyst was somewhat higher than that with the fresh CuO/γ -Al 2 O 3 catalyst. N 2 O formation increased with increasing reaction temperature. Ammonia (NH 3 ) slip increased with increasing gas velocity and decreased with increasing reaction temperature.

Novel Fluidized Bed Reactor for Integrated NOx Adsorption−Reduction with Hydrocarbons

“…For NH 3 -SCR of NO x , fluidized bed reactors have been used for NO x or simultaneous SO x /NO x removal by various SO 2 sorbents and NH 3 -or urea-SCR catalysts (Snip et al, 1996;Gao et al, 1996;Roh et al, 2003). Compared to conventional monolithic reactors, the catalyst loading is decreased, fly ash can easily pass through and the gas/solid contact efficiency is enhanced in the fluidized bed reactor.…”

The role of reaction kinetics and mass transfer in the selective catalytic reduction of NO with NH3 in monolithic reactors

“…They are among the most dangerous air pollutants, as they contribute to the greenhouse effect, participate in photochemical reactions that cause acid rain and the formation of troposphere ozone ('photochemical smog'), and have an important role in lakes and rivers eutrophication. In addition, they are harmful to human health, as they can damage the respiratory system …”

“…Metal oxide catalysts (oxides of copper, iron or vanadium, either unsupported or supported on alumina, silica or titania) are cheaper, and work well in the typical temperature range of industrial applications. One of the most common industrial SCR catalyst types is vanadium oxide, promoted by MoO 3 or WO 3 , and supported on titania (in the anatase form).…”