Dehydrogenation of ethane to ethylene over a highly efficient Ga2O3/HZSM-5 catalyst in the presence of CO2

Dehydrogenation of ethane to ethylene in the presence of carbon dioxide was investigated over various gallium-based catalysts. Ga2O3/HZSM-5 catalysts show better stability than beta-Ga2O3, and the higher Si/Al ratio HZSM-5 supported gallium oxide catalysts are more resistant to deactivation. The Ga2O3/HZSM-5(97) catalyst exhibits both high activity and stability for dehydrogenation of ethane, with an ethane conversion of 15% and ethylene selectivity of 94% without any observable trend of deactivation in 70 h. The results of NH3-TPD and FT-IR spectra of adsorbed pyridine revealed that the enhancement of the catalyst stability with increasing Si/Al ratio of the support is caused by the decrease of the acidity of the catalysts, resulting in the suppression of the side reactions, such as cracking and oligomerization. The promoting effect of CO2 on the dehydrogenation reaction is attributed to the reverse water gas shift reaction. The catalyst stability is also enhanced by the introduction of CO2. (C) 2009 Elsevier B.V. All rights reserved.