Feng T, Vohs J M
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6393, USA.
J Phys Chem B. 2005 Feb 17;109(6):2120-7. doi: 10.1021/jp040165k.
The partial oxidation of methanol and ethanol on silica-supported vanadium oxide catalysts was studied using temperature-programmed desorption (TPD), Raman spectroscopy, and diffuse reflectance infrared spectroscopy (DRIFTS). Methanol TPD results for V2O5/SiO2 samples as a function of vanadia loading in conjunction with X-ray diffraction data and Raman spectra indicated that dispersed vanadia on silica agglomerates into vanadia crystallites during a CH3OH TPD experiment. For ethanol-dosed samples, agglomeration of the dispersed vanadia was less severe, and it was possible to measure the activation energy for the dehydrogenation of adsorbed ethoxides to produce CH3CHO. Assuming a preexponential factor of 10(13) s(-1), the activation energy for this reaction was estimated to be 132 kJ/mol. The results of this study further demonstrate that there is a relatively weak interaction between vanadia and silica and suggest that adsorbed methoxide species help facilitate agglomeration of dispersed vanadia.
采用程序升温脱附（TPD）、拉曼光谱和漫反射红外光谱（DRIFTS）研究了甲醇和乙醇在二氧化硅负载的钒氧化物催化剂上的部分氧化反应。结合X射线衍射数据和拉曼光谱，研究了V2O5/SiO2样品的甲醇TPD结果与钒负载量的关系，结果表明，在CH3OH TPD实验过程中，二氧化硅上分散的钒氧化物会团聚成钒氧化物微晶。对于乙醇负载的样品，分散的钒氧化物的团聚程度较轻，并且可以测量吸附的乙醇盐脱氢生成CH3CHO的活化能。假设指前因子为10(13) s(-1)，该反应的活化能估计为132 kJ/mol。本研究结果进一步表明，钒氧化物与二氧化硅之间存在相对较弱的相互作用，并表明吸附的甲氧基物种有助于促进分散的钒氧化物的团聚。
