抄録
The dovelopment of high-temperature desulfurizing absorbent-typedenitrification catalysts for the simultaneous removal of H25 and NH3 were investigate to contribute to the abatement of SQx·Ox emission in the multi-step fluidized bed coal combustion and coal gasification combined cycle electric powerplants.
The desulfurizing absorbent-type denitrification catalysts prepared, were composed of multi-components (active catalyst for NH3 decomposition, desulfurizing absorbent for H2S, and sup-portmaterial). Fe was used as a catalyst for decomposition of NH3 to H2 and N2, BaO andCaO as absorbents forH2S, and Al2O3, TiO2, SiO2, and MgO as supports. Inlet reaction gases were mixtures of various composition of H2S (0, 600ppm), COS (0, 500Ppm), SO2 (0, 500ppm), NH3 (0, 500ppm), HCN (0, 500ppm), NO (0, 500ppm), H2 (0, 2.5%), CO (0-10%), CO2 (0-5%), H2O (0-10%) and N2 balanced. The experiments were carried out using a flow type packed bed reactor under atmospheric pressure at700-950°C.
The main results obtained are as follows:
1) The catalysts containingBaO have considerably higher reactivity with H2S than the catalysts containingCaO.
2) BaO andCaO form the compound-metal oxides with Al2O3, TiO2 and SiO2, except MgO.
3) In a series of catalysts containing the same kinds of desulfurizing absorbent and support, the catalysts where absorbent/support mole ratio is nearly equal to the composition of the compound-metal oxide, give the highest activity for NH3 decomposition, respectively.
4) ExcessBaO freed from the compound-metal oxides give higher reactivity withH2S, but the coexistence of support is required for both the elevation of catalytic activity for NH3 decomposition and the regeneration stability ofcatalysts.
5) 5wt%Fe/ [BaO (70mol%)-Al2O3 (30mol%)] is the most preferable catalyst for not only the simultaneous removal H2S (COS) and NH3, but the regeneration stability of catalysts.
6) The suitable regeneration procedure is to oxidize BaSformed to BaSO4 with H2O (8.5%)-O2 (18.5%)-N2 at 800°C, and then to convert BaSO4 to BaO (BaCO3) with H2 (5%)-CO2 (33.3%)-H2O (33.3%)-N2 at 800°C.
