The steady state rates of ethene and diethyl ether formation in parallel ethanol dehydration reactions at 573 and 623 K are mechanistically and kinetically described by the same rate expression on different alumina materials (α-, γ-, and η-Al2O3), implying that alumina materials have similar surface sites under reaction environments. In situ chemical titration using pyridine as a titrant elucidates similar site densities (∼0.12 sites nm-2 and ∼0.07 sites nm-2 for ethene formation and ∼0.14 sites nm-2 and ∼0.09 sites nm-2 for diethyl ether formation on γ- and η-Al2O3, respectively) on γ- and η-Al2O3 indicating that similar surface features exist on both γ- and η-Al2O3. Pyridine-ethanol co-feed experiments show that pyridine inhibited the formation of ethene to a greater extent than diethyl ether suggesting that the two parallel dehydration reactions are not catalyzed by a common active site.
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We appreciate financial support from The Dow Chemical Company. We also acknowledge Dr. Donghun Kim for taking SEM images and Dr. Hsu Chiang and Joseph F. DeWilde for helpful technical discussions.
© 2016 The Royal Society of Chemistry.
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