Application of in-situ temperature programmed techniques to catalytic oxidation reactions on conducting mixed oxides
- 122 Downloads
A test bed for development of catalysts in a temperature programmed reactor is described. The effluent species are monitored in real time. Such data are collected into spreadsheet arrays which can be interrogated to yield kinetic data. An appropriate reactor design can therefore proceed directly from laboratory measurements to generate whole plant simulation analysis and commercial evaluation. For the oxidative coupling of methane, the hydrocarbon to oxygen ratio in the feed is of particular importance since the state of oxidation plays a significant role in determining the selectivity of the catalyst to the optimum product distribution. Homogeneous gas phase reactions may also occur at high temperatures, hence the reactor volume both upstream and downstream of the catalyst must also be considered.
The stability of the catalyst under reactor conditions can be further assessed by following temperature programmed, thermal gravimetric and differential thermal analyses in diverse oxidizing, reducing or reaction atmospheres. Temperature programmed AC electrical measurements also give further insight into changes in the catalyst both at the surface and in the bulk as chemical reactions proceed. Examples of these techniques on a variety of mixed oxides such as Li-Ni-Co-O, La-Sr-Co-Fe-O and K-β′' alumina are presented.
KeywordsDifferential Thermal Analysis Mixed Oxide Catalytic Oxidation Product Distribution Simulation Analysis
Unable to display preview. Download preview PDF.
- J. Haber, “Mechanism of Heterogeneous Catalytic Oxidation” in Catalytic Oxidation, Principles and Applications, ed. R.A. Sheldon and R.A van Santen, 1995, World Scientific, Singapore, p 17.Google Scholar
- J. Haber, ACS Symp. Ser.638, 20 (1996).Google Scholar
- S.T. Oyama, ACS Symp. Ser.638, 2 (1996).Google Scholar
- Z. Zhang, X.E. Verykios and M. Baerns, Catal. Rev.-Sc. Eng.36, 507 (1994).Google Scholar
- J-L. Dubois and C. J. Cameron, Applied Catal.67, 49 (1990).Google Scholar
- D. Qin, A. Ovenston, A. Villar and J.R. Walls, ACS Symp. Ser.638, 95 (1996).Google Scholar
- M. Caldararu, A. Ovenston and J.R. Walls, Appl. Cat. A, 1997, in press.Google Scholar
- G. Schäfer and F. Aldinger, Ceramic Forum Int.73, 109 (1996).Google Scholar
- F. Martín-Jiméniz, J.M. Blasco, L.J. Alemany, M.A. Banares, M. Faraldos, M.A. Peña and J.L.G. Fierro, Catal. Lett.33, 279 (1995).Google Scholar
- X. Bao, M. Muhler, R. Schlögl and G. Ertl, Catal. Lett.32, 185 (1995).Google Scholar
- Y. Tong and J.H. Lunsford, J.Chem. Soc., Chem. Commun. 792 (1990).Google Scholar
- A. Ovenston, D. Qin and J.R. Walls, J.Mater.Sci.30, 2496 (1995).Google Scholar
- G.B. Marin, “High Temperature Oxidation Processes: Oxidative Coupling of Methane” in Catalytic Oxidation, Principles and Applications, ed. R.A. Sheldon and R.A. van Santen, 1995, World Scientific, Singapore. p 119.Google Scholar
- Y.S. Ling and Y. Zeng, J. Catal.164, 220 (1996).Google Scholar
- K. Omata, O. Yamazake, K. Tomita and K. Fujimoto, J. Chem. Soc., Chem. Commun., 1647 (1994).Google Scholar