Item

Abstract

In many industrial processes catalyst deactivation is caused by formation of carbonaceous deposits (“coke”) on the catalyst surface. Development of catalysts that are less prone to deactivation requires understanding the nature of the carbonaceous species and the formation routes. In situ spectroscopic methods could be very informative in this respect, as they give information about the state of the surface including adsorbates and allow correlations with catalytic performance.
Sulfated zirconia (SZ) materials are active catalysts for hydrocarbon transformation at low temperatures but often deactivate rapidly. Many authors suggested that the reason for the deactivation of SZ catalysts is the formation of “coke” at the active sites [1-3].
In our present work we sought to identify the surface species formed during n-butane isomerization on SZ catalysts by in situ UV–vis–NIR spectroscopy using three types of experiments: 1) Changes during reaction were monitored. 2) Deposits were transformed in a post-reaction treatment with different reactants. 3) Reference spectra were recorded. Specifically butene was adsorbed, which has been proposed as an intermediate in n-butane isomerization over SZ [4], but is also considered responsible for catalyst deactivation [5].
1. F.R. Chen, G. Coudurier, J. Joly, J.C. Védrine, J. Catal. 143 (1993) 616.
2. F. Garin, D. Andriamasinoro, A. Abdulsamad, J. Sommer, J. Catal. 131 (1991) 199.
3. R.A. Comelli, C.R. Vera, J.M. Parera, J. Catal. 151 (1995) 96.
4. V. Adeeva, H.-Y. Liu, B.-Q. Xu, W. Sachtler, Topics in Catalysis 6 (1998) 61.
5. Z. Hong, K. B. Fogash and J. A. Dumesic, Catal. Today 51 (1999) 269.