To simplify the purification process of hot effluent gases produced by biomass and/or coal gasification, an integrated technique employing dual layer granular beds for the simultaneous removal of particulates and tar at high temperature (750-850 degrees C) has been proposed. Compared to the well studied process of particulate removal, investigations for the catalytic cracking of tar are inadequate. The present work conducted an experimental study of the catalytic cracking of tar based on two model compounds: toluene and methylnaphthalene. The experiments were conducted on a granular bed filter with an inner diameter of 40 mm and a height of 1000 mm. The catalytic cracking performances on an expanded perlite granule layer, an olivine granule layer, and a dual layer granular bed comprised of an upper layer of expanded perlite granules and a lower layer of olivine granules were investigated individually. It was found that the expanded perlite granule layer alone was effective for toluene cracking, and the efficiency was increased with increasing reaction temperature and gas residence time. The olivine granule layer provided excellent catalytic activity for toluene cracking. Furthermore, olivine granules exhibited significantly improved catalytic activity when calcinated at temperatures greater than 900 degrees C, or impregnated with NiO. The conversion efficiencies of toluene and methylnaphthalene attained values as great as 98.89% and 79.33%, respectively, at a temperature of 800 degrees C over a dual layer granular bed comprised of a 150 mm thick upper layer of expanded perlite granules and a 50 mm thick lower layer of 3 wt% NiO impregnated olivine granules. (C) 2016 Elsevier Ltd. All rights reserved.