Comparative catalytic performance of microreactor and fixed-bed reactor for H2 production from partial oxidation of dimethyl ether

Abstract

Stainless-steel mesh supported catalyst microreactor was fabricated and its catalytic efficiency was compared with that of fixed-bed reactor for H2 production from partial oxidation of dimethyl ether (DME). The microreactor system (stainless steel mesh/γ-Al2O3/Ni-Mg spinel) sustained 100 % DME conversion with H2 selectivity above 75 % after 25 h time on stream at 600 °C. In contrast, the fixed-bed reactor (γ-Al2O3 balls/Ni-Mg spinel) initially, showed 100 % DME conversion but within 10–15 h, both conversion and H2 selectivity declined-falling to 60 % and 40 %, respectively by 100 h time on stream. Better catalytic efficiency of microreactor than that of fixed-bed reactor considered due to better heat and mass transfer properties of stacked stainless steel mesh supported catalysts as well as formation of carbon nanofibers (CNFs) carrying Ni particles on their tips during partial oxidation of dimethyl ether (DME). These CNFs were considered to enhance heat transfer in mesh-supported catalysts along with Ni active sites, contributing to stable catalytic performance. Alternatively, in fixed-bed reactor, formation of carbon nanofibers (CNFs) on catalysts surface caused deterioration by covering the active sites of Ni-Mg spinel catalysts and consequently, poor performance was obtained during long-term stability test. Moreover, tortuosity properties of stainless steel mesh supported catalysts enabled better mixing of reactants through narrow porous microstructures that resulted in a turbulent flow and caused the stable performance of the microreactor.