C9 ALKYL-AROMATICS REACTIONS OVER NI (BI)/MOR CATALYSTS IN MILD CONDITIONS

摘要

These aromatics (such as benzene, toluene, and xylenes) are mainly provided in the refinery by the reforming unit through the hydrodealkylation (HDA) reaction which consumes hydrogen (1, 2). In petrochemistry, the demand for aromatics remains strong, and in this case, these operating conditions are adapted to produce high aromatic content. The refiners’ interest is therefore to control and to orientate these HAD reactions depending on the aromatic levels desired. Various catalysts are given in the literature (3, 4, 5) for the hydrodealkylation reactions. Commercial catalysts are usually Cr/Al2O3 catalysts. Nickel impregnated with mordenite or exchanged over dealuminated mordenite is the most popular catalyst and is used, for example, in the Tatoray and TransPlus commercial processes. Their synthesis methods are generally undisclosed. In the current paper, the main objective is to evaluate the role of metallic and acidic functions in the kinetics and the mechanisms of HDA of n-propylbenzene, (n-PB) used as a model molecule. For this purpose, in contrast with previous published results, this work was carried out under industrial conditions (573-793 K, 8 bars total pressure, H2/HC=6) over model catalysts. Close to the actual production conditions for catalyst future applications will have a critical impact. MOR-supported Ni and Bi catalysts were chosen to evaluate the effect of the metallic function on the aromatic distribution. Moreover, the acid and metal site density and strength distribution are both important and their proper balance is critical in determining the activity of these catalysts.