Am. Prakash et al., SYNTHESIS AND CHARACTERIZATION OF THE LARGE-PORE MOLECULAR-SIEVE SAPO-46, Journal of the Chemical Society. Faraday transactions, 91(6), 1995, pp. 1045-1050
Citations number
24
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
Synthesis of a novel large-pore SAPO-46 molecular sieve has been descr
ibed. The effect of the organic template (di-n-propylamine) and silica
concentration in the synthesis gel on the crystallinity and phase pur
ity of SAPO-46 was studied. Samples were characterized by X-ray diffra
ction (XRD), magic-angle spinning (MAS) NMR spectroscopy, FTIR spectro
scopy, thermal analysis (TG and DTA), chemical analysis, scanning elec
tron microscopy and EDAX microprobe analysis, SAPO-46 had a lower ther
mal stability than SAPO-5, SAPO-37 and MgAPO-36. Silicon substitution
for phosphorus at crystallographically distinct sites has been suggest
ed to cause the creation of two different silicon environments in SAPO
-46. The extent of silicon substitution was large and temperature-prog
rammed desorption (TPD) of ammonia has shown high concentration of ac
id sites. SAPO-46 showed high activity for alkylation of toluene with
methanol that was comparable with that of ZSM-5, but showed no para se
lectivity. However, as the reaction proceeded, para selectivity develo
ped due coking at the pore mouth.