抄録
A dry method to remove simultaneously SOx and NOx with CuO-Al2O3-TiO2 was investigated. This method is based on the principle that SOx can be removed by the sulfation with CuO (SO2+ (1/2) O2+CuO-CuSO4, SO3+CuO→CuSO4) and NOx removed by the catalytic reduction with NH3 (NO+NH3+ (1/4) O2→N2+ (3/2) H2O, NO2+ (4/3) NH3→ (7/6) N2+2H2O, NO+NO2+2NH3→2N2+3H2O) over CuSO4 formed. Thus, the most important problem for practical use of this process is to develop a technique to regenerate repeatedly the-catalyst employed. The experiment for removal of SOx and NOx was carried out using a flow type packed bed reactor under atmospheric pressure at 350°C. The inlet gas was 1000ppm SO2-500ppm NO-667ppm NH3-5%O2-10%H2O-N2. The metal oxides were prepared by the coprecipitation from CuSO4, TiCl4 aq. etc. with NH3 aq., The examinations for regeneration were carried out by reduction with NH3, etc. or by thermal decomposition. The third components added to CuO-TiO2 as an improvement agent were Al2O3, SiO2, Fe2O3 or V2O5. The following results were obtained: 1) 40-50mol%CuO-60-50mol%TiO2 was suitable for only a SOx absorbents. The regeneration of these solids was possible by mild reduction (CuSO4→Cu3N) with NH3-H2O mixture (1% NH3-7.4% H2O-N2) at 400°C, and then by mild oxidation (Cu3N-CuO) with O2-H2O mixture (5% O2-10% H2O-N2) at 350°C. 2) 40mol%CuO-20mol% Al2O3-40mol% TiO2 was the metal oxides of the most preferable composition for the dry simultaneous removal of SOx and NOx. This regeneration was carried out sufficiently by the reduction (CuSO4→Cu3N) with 20% NH3-7.4% H2O-N2 at 400°C, and then by the oxidation (Cu3N→CuO) with 5% O2-10% H2O-N2 at 350°C.
