Activity And Stability Study Of An Al₂O₃-Coatde Cordierite Honeycomb Supported CuO Catalyst For SCR Of No By NH₃

Coal is the main primary energy in China, the annual emission of nitrogen oxides(NOX)from fule gas increased rapidly, NOX has caused great harm to the ecological environment and human health. One of the available technologies that can effectively control the emission of nitrogen oxides is the selective catalytic reduction (SCR) of nitrogen oxides with ammonia. Currently, the most widely employed catalysts in the SCR process are V2O5/TiO2/honeycomb catalysts, which have an optimum temperature range of 350-450℃for reaction, with NO conversion of higher than 90%. At the same time, because of the high cost, the technology is only in the demonstration phase in China. Now, one of the most important directions is to develop a new inexpensive catalyst system to replace the V2O5/TiO2/honeycomb Relatively, CuO/Al2O3 catalyst is low-cost, and is reported to show good activities for SO2 adsorption and NO reduction by NH3 at 350-450℃. When used for removel of NO alone, the adsorption of SO2 can decreased NH3 over oxidation to NO. A12O3 coated-cordierite honeycomb supported with CuO, after being sulfated by SO2, exhibits high activities for selective catalytic reduction (SCR) of NO with NH3 at 350-450℃. To optimiza A12O3 coating methods can further improve the activities of the catalysts.Therefor, the attention of this work is to develop a honeycomb cordierite-based CuO/Al2O3, the activities and stabilities of such a catalyst were studied systematically. The main results are described in the following.(1) Use kinds of honeycomb cordierites which have already been coated with A12O3 and CeO2 (when used) as the carrier, then supported with CuO, after being sulfated by SO2, exhibits high activities for selective catalytic reduction (SCR) of NO with NH3 at 350-450℃, with NO convertion of about 95%. CuO was introduced on the ceramic samples by impregnation using a cupric nitrate solution, with a concentration range from 1%-2%.(2) CeO2, at sodium loading of 0.8% and 2.8%, both have little effects to the SCR activity, but it can affect the stability of the catalyst Significantly. After 400h's reaction, the catalyst of sodium loading of 2.8% shows good stability, with NO convertion always higher than 85%.(3) The activity of honeycomb CuO/Al203/cordierite to honeycomb V2O5/TiO2/cordierite and honeycomb CuO/Al2O3/cordierite to industrial V2O5/TiO2 catalysts is compared. Honeycomb CuO/Al2O3/cordierite catalyst shows high activities, with potential industrial application.(4) The stability of honeycomb CuO/Al2O3/cordierite is affected by gas hourly space velocity (GHSV).