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Theoretical study of the Ga/SAPO-11 catalyst: Extra-framework gallium species and n-butane transformation

Abstract:

Calculations to study the interaction of Ga+, [GaO]+ and Ga2O with a Brönsted acid site of a SAPO-11 silicoaluminophospates were carried out using the semiempirical MSINDO approach. The SAPO-11 structure was modeled by a ring of 10 tetrahedrons and 3 rings of 10 tetrahedrons system. The calculations show that the formation of [HGaOH] + and [GaH2]+ species by reduction with H 2 are thermodynamically favored. The transformation of [HGaOH] + into Ga+ and water is highly endothermic. The Ga 2O react with the Brönsted acid site to produce anchored species, which can be reduced by molecular hydrogen to give [Ga(GaH)(OH)] and [GaOGaH2]. The Ga+ and Ga2O reactions with n-butane to produces butenes are all endothermic. © 2005 Elsevier B.V. All rights reserved.