LAUSR

Abstract In order to correlate the physicochemical properties of carbon-covered alumina (CCA) materials with their catalytic performance for oxidative dehydrogenation of ethylbenzene with CO 2 (CO 2 -ODEB), a series of CCA materials with diverse carbon contents (8.7–31.3 wt%) and pyrolysis temperatures (600–800 °C), which were synthesized via an impregnation method followed by pyrolysis, were applied. These catalytic materials were characterized by TGA, N 2 physisorption, XRD, Raman spectroscopy and XPS techniques. It was found that the catalytic performance of these CCA materials highly depended on their physicochemical properties, and the optimum CCA catalyst exhibited much better catalytic stability than conventional hydroxyl carbon nanotubes. Below an optimum value of carbon content, the CCA catalyst preserved the main pore characteristics of the Al 2 O 3 support and its catalytic activity increased with the carbon content. Excessive carbon loading resulted in significant textural alterations and thereby decreased both the ethylbenzene conversion and styrene selectivity. On the other hand, high pyrolysis temperature was detrimental to the ordered graphitic structure of the carbon species within the Al 2 O 3 pore. The decreased ordered graphitic degree was found to be associated with the loss of the surface active carbonyl groups, consequently hampering the catalytic efficiency of the CCA catalyst.