| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 148795 | Chemical Engineering Journal | 2013 | 8 Pages |
Catalytic conversion of i-butane over Zn-modified HZSM-5 catalyst was systematically investigated at different reaction pressures. A special fixed-bed reactor involving a vacuum unit which could modulate reaction pressure from subatmospheric to positive pressure was used. Results show that reaction pressure can change the initial activation and subsequent reaction paths of i-butane over Zn/HZSM-5 catalyst. At subatmospheric pressure, the decrease in reaction pressure favors the dehydrogenation of i-butane, meanwhile inhibits both the cracking of i-butane and the secondary reactions such as the oligomerization, cracking and aromatization. Consequently, the selectivities to the undesired by-products (methane and ethane) are notably abated, and the selectivities to the desired products (ethylene, propylene and aromatics) significantly increase. Although space velocity affects the reaction paths for i-butane conversion, the change in reaction pressure has a more profound effect on the reaction paths.
Graphical abstractReaction pressure is a key factor for i-butane conversion paths over Zn/HZSM-5. At subatmospheric pressure, it effectively inhibits the cracking of i-butane to by-products (methane and ethane), but promotes the dehydrogenation of i-butane to desired products (ethylene, propylene, butenes and BTX). At subatmospheric pressures, the reaction is controlled by kinetic, however at positive pressures it is controlled by thermodynamic.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights• Special fixed-bed reactor adjusts reaction pressure from vacuum to positive pressure. • A decrease in reaction pressure changes i-butane conversion paths on Zn/HZSM-5. • The cracking activation of i-butane decreases with reaction pressure. • The dehydrogenation of i-butane increases with the decrease of reaction pressure. • The selectivity to desired products increases with the decrease of reaction pressure.
