SO2 ADSORPTION ON TYPE Y ZEOLITE SYNTHESIZED FROM COAL FLY ASH

Ca- exchanged zeolite Y was prepared using coal combustion fly ash as a source of silica . This zeolite was characterized by chemical analysis, X-ray diffraction, N 2 adsorption and scanning electron microscopy. Its behaviour in SO 2 removal at 100oC, 0%-6% H 2 O (v/v), 5% O 2 (v/v), 1000 ppmv SO 2 and spatial velocity of 1015 h -1 was evaluated. The obtained results show that SO 2 removal capacity of fresh samples is high, decreasing to an almost constant value after some cycles of adsorption/desorption in absence of water in the gas stream. In presence of water the adsorption proceeds via H 2 SO 4 formation, as the CaSO 4 detected in exhausted samples by XRD and FTIR analysis indicates. The formed H 2 SO 4 produces a severe alteration in the zeolite structure that is responsible for its decreasing activity along several cycles adsorption-desorption.