Trimethylgallium (TMGa) was loaded by chem. vapor deposition (CVD) on two different zeolites, H-ZSM5 and H-MOR. The interaction of TMGa on zeolite acid sites and the effect of redn. and oxidn. treatments were characterized by ICP, XPS, FT-IR and 71Ga NMR. The capacity of dissociatively adsorption of H2 and D2 and the resultant HD desorption was analyzed by H2-D2 exchange reaction. The oxidn. and specially the redn. treatment provoke the migration and redistribution thought zeolite crystals. FT-IR results show that TMGa reacts with both silanol and sterically accessible Bronsted acid sites. 71Ga NMR spectra show that Ga is presents in two different geometries: octahedral and Ga compensating the neg. charged Al from the framework zeolite structure. Hydrogen pretreatment of both zeolites has a pos. effect on the distribution of Ga. However, Ga species obtained were less active for H2-D2 exchange than the Ga species obtained after oxidn.
|Name||Studies in Surface Science and Catalysis|
|Conference||conference; International FEZA conference ; 2 (Taormina) : 2002.09.01-05; 2002-09-01; 2002-09-05|
|Period||1/09/02 → 5/09/02|
|Other||International FEZA conference ; 2 (Taormina) : 2002.09.01-05|