Methanol conversion to light olefins over sonochemically prepared SAPO-34 nanocatalyst

Methanol conversion to light olefins was investigated over sonochemically prepared SAPO-34 nanocatalyst (SONO-SAPO-34) with crystal sizes of about 50 nm and its catalytic properties were compared with those of 600 nm SAPO-34 catalyst synthesized hydrothermally (HT-SAPO-34). Both catalysts were used to elucidate the effect of crystallite size on their catalytic performance, especially in terms of life time. The product distribution over the two catalysts is almost the same, although their deactivation behaviors differ considerably. The HT-SAPO-34 catalyst with large crystals deactivates rapidly, while the SONO-SAPO-34 nanocatalyst retains its activity for a long time. This variation in catalytic deactivation according to the crystallite size of the SAPO-34 catalysts is attributed to the number of accessible cavities near their external surface and the diffusion limitation of the reactant and product molecules. (C) 2012 Elsevier Inc. All rights reserved.