OP-II-3

PP-II-56MODELING OF CATALYTIC MICROREACTORSFOR NAPHTHA STEAM REFORMINGMustafa Karakaya, Ahmet K. AvciDepartment of Chemical Engineering, Bogazici University, Bebek 34342,Istanbul, Turkey, avciahme@boun.edu.trThis study involves comparison of two microreactor configurations, the multipleadiabatic bed (MAB) and the microchannel reactors, to produce hydrogen needed todrive a 2-kW PEM fuel cell. In the MAB system, composed of adiabatic catalyticpacked beds and microchannel heat exchangers interconnected to each other,hydrogen is produced via steam reforming (SR) of n-heptane, model compound fornaphtha, in a number of adiabatic reactors packed with a Ni-based catalyst. Heatrequirement of endothermic SR is supplied by exothermic combustion of methanerunning in a separate array of adiabatic reactors packed with a Pt-based catalyst.Heat transfer between the two reactions is achieved in microchannel heatexchangers that connect the effluent streams of the combustion and reforming beds.Upon heat exchange the streams are fed to the successive adiabatic beds and thereaction-heat exchange cycle is repeated until the desired amount of hydrogen isproduced [1,2].The second configuration, microchannel reactor, has parallel, identical channelswith dimensions in the sub-millimeter range and is characterized by laminar flowconditions. The microchannel reactor design in this study involves n-heptane SR inchannels whose walls are coated by a Ni-based catalyst. Heat needed to drive SR issupplied by methane combustion running in parallel channels coated with a Pt-basedcatalyst. Sets of parallel, straight channels, all of which have identical square crosssections,are etched on metallic plates and coated with either a Ni- or Pt-basedcatalyst. The plates are then bonded on top of each other so as to form an alternatingstack of endothermic and exothermic channels. Heat transfer between the channelsof the same plate is assumed to be negligible, allowing the multichannel system to becharacterized by a representative unit involving a single pair of exothermic andendothermic channels separated by a metallic wall. The system operates at steadystate and counter-current flow of reactive streams is considered.The representative microchannel unit is modeled by 2D continuity, momentum,energy conservation and species mass transport equations for the fluid and catalytic435