A Comparative Study for Synthesis of SAPO-34 by Different Templates; TEAOH and Morpholine

Synthesis of the SAPO-34 molecular sieve by hydrothermal crystallization method and using two kinds of templates; TEAOH, morpholine and their combination has been studied. Three different samples were prepared by different molar ratios of templates to figure out the effect of the mentioned templates on the size, uniformity and crystallinity of the product. One of the samples was made by pure TEAOH. Another one made by pure morpholine, and the last one was prepared by a mixture of equal molar ratios of morpholine and TEAOH. The synthesized molecular sieves were characterized by XRD, SEM, EDX and BET techniques. The results confirmed formation of the SAPO-34 by pure morpholine with average particle size of 1.5-10 μm, whereas the average size of the particles formed by pure TEAOH was 1.5-3 μm. The sample synthesized by the combination of TEAOH, and morpholine represented the best quality of the product according to the crystallinity and size uniformity with the average particles size of 1.0 μm. This sample was examined in MTO reaction at 673 K and feed WHSV of 8.7 h-1 to verify its performance in this process. The selectivity and yield of light olefins were attained for this sample. The selectivity to light olefins was about 1.8.