Simulation of a membrane reactor for the catalytic oxydehydrogenation of ethane

M.L. RODRIGUEZ; D.E. ARDISSONE; E. HERACLEOUS; A. A. LEMONIDOU; E. LÓPEZ; M. N. PEDERNERA; D.O. BORIO

Ixtapa-Zihuatanejo, MEXICO

Congreso; Mexican Congress on Chemical Reaction Engineering - MCCRE 2008; 2008

The ethane oxidative dehydrogenation (ODH) appears as the most promising alternative to the conventional process of thermal cracking (pyrolysis) of naphtha or ethane for industrial ethylene production. The ODH reaction is carried out in the presence of a suitable catalyst, competing with the undesired complete combustions of ethane and ethylene. Contrary to the highly endothermic and equilibrium-limited thermal cracking process, in the ODH process the reactions are irreversible and exothermic. Ethane ODH has been studied over a wide range of catalytic materials [1,2]. Recently, Heracleous and Lemonidou [3,4] reported the development of bulk Ni-Nb-O mixed oxides as both highly active and selective catalytic materials for the desired reaction. Multitubular reactors are commonly used in industry to carry out these exothermic processes, focusing on the control of the reaction temperature as a key factor to maintain good selectivity levels [5]. An attractive alternative to these fixed-bed reactors is the use of a membrane reactor to axially distribute the oxygen injection in the reaction media (see Fig. 1). As reported by Heracleous and Lemonidou [3,4], lower oxygen partial pressures increase the selectivity, decreasing the generated heat and increasing the ethylene yield. The oxygen distribution also allows better heat management, as it leads to a diminution of the local reaction rates and, consequently, of the rate of heat generation. Furthermore, in the case of flammable mixtures, as in this case, the oxygen distribution through the membrane prevents the local generation of dangerous concentrations and allows operation under normally prohibitive reaction mixture concentrations. [1] M.A. Banares, Catal. Today, 51 (1999) 319. [2] T. Blasco, J.M. Lopez-Nieto, Appl. Catal. A., 157 (1997) 117. [3] E. Heracleous, A.A. Lemonidou, J. Catal., 237 (2006) 162. [4] E. Heracleous, A.A. Lemonidou, J. Catal., 237 (2006) 175. [5] P. Arpentinier, F. Cavani, F. Trifiro “The Technol. of Catalytic Oxidations”, Technip, Paris, 2001.