Applied Catalysis A: General 241 (2003) 25–38 Ethylene conversion on activated carbon-supported NiMo catalysts: effect of the support Juan Matos, Jorge Laine ∗ Laboratorio de Fisicoqu´ ımica de Superficies, Centro de Qu´ ımica, Instituto Venezolano de Investigaciones Cient´ ıficas (IVIC), Apartado 21827, Caracas 1020-A, Venezuela Received 5 June 2002; received in revised form 26 July 2002; accepted 27 July 2002 Abstract The present work has been led to verify the influence of some physicochemical properties of carbon supports on the catalytic behaviour of hydrotreatment catalysts. The catalytic conversion of ethylene in presence of hydrogen was carried out at 300 ◦ C on Mo, Ni and NiMo catalysts supported on two different activated carbons (AC). The results were interpreted in terms of the hydrogenating/hydrogenolytic activity, catalytic stability and coking functions of catalysts. Changes observed both in activity and evolution of products as function of the final temperature of two reducing pretreatments indicate that H-type carbon-supported NiMo catalysts has much more tolerance to coke deposition and therefore they are less prone to suffer deactivations than catalysts based on L-type AC. The apparent rate constants and the initial rates of coke formation were estimated indirectly as an attempt to provide a better understanding the influence of chemical surface functionalities and of textural properties of AC. A correlation was found between these kinetic parameters of coke formation and the catalytic behaviour of catalysts. The results were compared with respect to a conventional alumina-supported NiMo catalyst indicating that using H-type AC as a support of hydrotreatment Ni-consisting catalysts we can be able to maintain high activities over longer periods of operation, at least, for the hydrogenation of simple insaturated hydrocarbons such as ethylene. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Activated carbon; Ethylene conversion; NiMo catalysts; Carbon deposition; Coking kinetics 1. Introduction The design of industrial catalysts for superior performance in certain applications and for the de- velopment of novel processes, requires a proper understanding of the catalyst surface structure and the various surface processes that can occur on the fresh catalysts during the catalytic reaction. One growing area in heterogeneous catalysis is the study of support/ ∗ Corresponding author. Fax: +58-2-504-1350. E-mail addresses: jmatos@quimica.ivic.ve (J. Matos), jlaine@quimica.ivic.ve (J. Laine). active phase interactions, since they can remarkably affect the catalytic behaviour of catalysts [1–27]. It is well known that alumina is the material most widely used by the industry for support precursor ox- ides of an element of group VIB (Mo or W) and an- other of group VIII (Ni or Co) in petroleum refining hydroprocessing applications such as hydrodesulfura- tion (HDS) and hydrodenitrogenation (HDN). Also, alumina-supported Ni-consisting catalysts are com- monly used in many industry processes such as hydro- genation, hydrogenolysis of hydrocarbons and steam reforming [11–27]. For these reasons, although much research has been reported on the characteristics and 0926-860X/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0926-860X(02)00427-1