SURFACE-ACIDITY OF SAPO-34 SILICOALUMINOP HOSPHATE

The nature and the acidic site strength distribution of a SAPO-34 sili coaluminophosphate, which shows good behavior in the selective transfo rmation of methanol into light olefins, have been studied. The techniq ues used have been FTIR spectrophotometry and calorimetric titration o f adsorbed ammonia. The small diameter of the crystal channels hinders the use of organic bases. The acidic structure is mainly constituted of Bronsted sites, with a noticeable presence of Lewis sites. The site s are moderately acidic compared with those of a HZSM-5 zeolite.