PREPARATION AND CHARACTERIZATION OF MG-CONTAINING AFI AND CHABAZITE-TYPE MATERIALS

Magnesium aluminophosphate with AlPO4-5 and AlPO-34 (chabazite (CHA)-t ype) structures have been synthesized by hydrothermal methods using tr iethylamine or tetraethylammonium as template. Different compositions of gel and varying the magnesium, template, and,/or water contents hav e been employed. It can be observed that MgAPO-5 is obtained from gels with low magnesium or template content and/or high water content, How ever, if gels with high magnesium or template content are used, MgAPO- 34 (CHA-type) mostly is obtained. Characterization results, such as th ermogravimetric analysis, unit cell parameters, FT i.r. of pyridine ad sorbed, and t.p.d. of ammonia, indicate that Mg is incorporated into t he framework of the molecular sieve. In addition, Bronsted acid sites, with a strength similar to that of high silica zeolites, were observe d on MgAPO-5.