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

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Año: 2009 vol. 48 p. 1090 - 1095

0888-5885

Industrial-scale ethylene production using a novel membrane multitubular reactor for the ethane oxidativedehydrogenation process over a Ni-Nb-O catalyst is proposed. A theoretical study was performed by means of a pseudohomogeneous model of the tube and shell sides. The feasibility and convenience of using this novel design, as well as the influence of the main operating variables on the reactor performance, were analyzed. The introduction of the membrane leads to lower oxygen partial pressures inside the catalyst tubes when compared with a conventional multitubular reactor. This leads to very good ethylene selectivities, good temperature control as a result of lower heat generation rates, and reasonable production rates. The reactor performance appears to be highly affected by the balance between the rate of oxygen consumption by the chemical reaction and its rate of permeation through the membrane. Under certain operating conditions leading to lower reaction rates, an undesired accumulation of oxygen inside the tubes is observed. A minimum amount of O2 injected at the tube mouth appears beneficial to overcoming this accumulation phenomenon. The membrane reactor shows a nonconve tional inverse parametric sensitivity with respect to the inlet temperature. When the reactor is operated at conditions where the reaction is controlled by the permeation flow of O2 through the membrane, it is possible to reach high selectivities to ethylene, significant ethane conversions, and mild temperature profiles.-Nb-O catalyst is proposed. A theoretical study was performed by means of a pseudohomogeneous model of the tube and shell sides. The feasibility and convenience of using this novel design, as well as the influence of the main operating variables on the reactor performance, were analyzed. The introduction of the membrane leads to lower oxygen partial pressures inside the catalyst tubes when compared with a conventional multitubular reactor. This leads to very good ethylene selectivities, good temperature control as a result of lower heat generation rates, and reasonable production rates. The reactor performance appears to be highly affected by the balance between the rate of oxygen consumption by the chemical reaction and its rate of permeation through the membrane. Under certain operating conditions leading to lower reaction rates, an undesired accumulation of oxygen inside the tubes is observed. A minimum amount of O2 injected at the tube mouth appears beneficial to overcoming this accumulation phenomenon. The membrane reactor shows a nonconve tional inverse parametric sensitivity with respect to the inlet temperature. When the reactor is operated at conditions where the reaction is controlled by the permeation flow of O2 through the membrane, it is possible to reach high selectivities to ethylene, significant ethane conversions, and mild temperature profiles.