Oxygen and Nitrous Oxide as Oxidants: Implications for Ethane Oxidative Dehydrogenation over Silica−Titania-Supported Molybdenum
Oxygen and Nitrous Oxide as Oxidants: Implications for Ethane Oxidative Dehydrogenation over Silica−Titania-Supported Molybdenum
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DOI：
10.1021/jp810664u
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发表时间：
2009-05
影响因子：
3.7
通讯作者：
M. P. Woods;Burcu Mirkelamoglu;U. Ozkan
中科院分区：
文献类型：
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作者：
M. P. Woods;Burcu Mirkelamoglu;U. Ozkan
使用O2或N2 O作为氧化剂测试10%Mo/Si-Ti催化剂的乙烷氧化脱氢（ODH）活性。在0.46至1.0 mg min/cm−3的接触时间下测试乙烷ODH活性。N2 O在给定的乙烷转化率下给出上级乙烯选择性，在所有测试的接触时间下都优于氧。当使用N2 O作为氧化剂时，乙烯选择性随着接触时间以慢得多的速率降低。X射线光电子能谱（XPS）实验表明，在乙烷ODH过程中，使用O2，催化剂中的钼被完全氧化为Mo（VI），而还原状态下降到平均+5.8时，使用N2 O作为氧化剂。在不同升温速率下对预还原的10%Mo/Si-Ti进行了程序升温氧化实验。当使用N2 O时再氧化的活化能为98 kJ/mol，而O2的活化能为41 kJ/mol，导致当O2是氧化剂时再氧化速率快至少1700倍。这种差异在利率帐户f.
A 10% Mo/Si−Ti catalyst was tested for ethane oxidative dehydrogenation (ODH) activity using either O2 or N2O as the oxidant. Ethane ODH activity was tested at contact times varying from 0.46 to 1.0 mg min/cm−3. N2O gives superior ethylene selectivities at a given ethane conversion outperforming oxygen at all contact times tested. Ethylene selectivities decrease with contact time at a far slower rate when using N2O as the oxidant. X-ray photoelectron spectroscopy (XPS) experiments demonstrate that molybdenum in the catalyst is fully oxidized to Mo(VI) during ethane ODH using O2, whereas the reduction state decreases to an average of +5.8 when using N2O as the oxidant. Temperature-programmed oxidation experiments of pre-reduced 10% Mo/Si−Ti were carried out at different temperature ramp rates. The activation energy of re-oxidation when using N2O is 98 kJ/mol, whereas that of O2 is 41 kJ/mol leading to a re-oxidation rate at least 1700 times faster when O2 is the oxidant. This difference in rates accounts f...