SO2 adsorption on type y zeolite synthesized from coal fly ash

Abstract

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, N2 adsorption and scanning electron microscopy. Its behaviour in SO2 removal at 100ºC, 0%-6% H2O (v/v), 5% O2 (v/v), 1000 ppmv SO2 and spatial velocity of 1015 h-1 was evaluated. The obtained results show that SO2 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 H2SO4 formation, as the CaSO4 detected in exhausted samples by XRD and FTIR analysis indicates. The formed H2SO4 produces a severe alteration in the zeolite structure that is responsible for its decreasing activity along several cycles adsorption-desorption.