科研之友
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摘要
This work reports a kinetic study of C3H6 catalytic partial oxidation (CPO) over Rh/alpha-Al2O3. CPO and steam reforming experiments were carried out in an isothermal annular reactor and quantitatively analyzed by a mathematical model following both a molecular and a microkinetic description of the surface reactivity. The results showed that, in line with that of other hydrocarbons such as CH4 or C3H8, the CPO of C3H6 proceeds according to an indirect route, which entails total oxidation at a temperature as low as 200 degrees C, followed by steam reforming at a temperature higher than 450 degrees C. However, differently from C3H8, C3H6 revealed a strong affinity with the Rh surface, which results in peculiar kinetic features. On the one hand, the total oxidation of C3H6 was found to be active at a much lower temperature than what was observed with C3H8. On the other hand, in the absence of O-2, the strong adsorption of C3H6 results in carbon poisoning of the catalyst surface that inhibits steam reforming at temperatures below 450 degrees C. Lumped rate expressions for C3H6 total oxidation and steam reforming have been developed based on the observed kinetic dependences. Such kinetic expressions represent a simple engineering tool and extend an existing molecular kinetic scheme for the CPO of light hydrocarbons. In addition, O-2-assisted and O-2-free activation steps of C3H6 have been added to an existing C-1 microkinetic scheme. The simulations pointed out that the extended scheme nicely described the high activity of C3H6 in total oxidation and the poisoning effect on steam reforming, and the O/Rh interaction turned out to be the critical parameter to correctly describe the observed reaction orders.
- 出版日期2014-2-5
