Synthesis and Characterization of SAPO-56, a New member of silicoaluminophosphate

The molecular sieve SAPO-56 has been synthesized hydrothermally using N,N,N ' ,N ' -tetramethyl-1,6-dihexane as template. In the Al2O3-SiO2-P2O5 mediu m, phase diagram of SAPO-56 was obtained. Pure phase region of SAPO-56 appe ared in the range of 0.5 <n(SiO2)/n(M)<0.7(M =SiO2 + Al2O3 + P2O5), 0.15 <n (Al2O3)/n(M)<0.4 and 0.1 <n(P2O3)/n(M)<0.3. The effect of template amount o n the synthesis of SAPO-56 was also investigated. Provided that other compo sitions (Sit Al, P and H2O) was fixed, it presented pure SAPO-56 crystal in the ratios of n(TMHD)/n(P2O5)greater than or equal to2 The properties of S APO-56 were characterized by XRD, SEM TG-DTA, IR and adsorption technique w hich suggested that SAPO-56 had a good thermal stability and large water ad sorption capacity, In the methanol-to-olefins reaction, SAPO-56 catalyst ex hibited a high activity and selectivities to C-2, C-3 olefins.