Assessment and optimization of the mass-transfer limitation in a metal foam methanol microreformer

Abstract

The performances of a methanol steam microreformer, constructed of CuZn metal foam coated by CuZnAlZr catalyst, were compared with those of a conventional packed-bed reactor. By variation of temperature, catalyst thickness and superficial velocity, the external and internal mass transfer in the microreformer was investigated. The external mass transfer can be ignored due to the high mass transfer coefficient of the metal foam. The internal diffusion resistance of the catalyst depends on the calcination temperature and catalyst/Al2O3 binder ratio of catalyst layer over metal foam, due to the development of catalyst pores. With optimum preparation conditions, the critical thickness to eliminate internal mass transfer limitation is about 8 μm. The improved external and internal mass transfer resulted in a methanol conversion increase of about 10% in microreformer compared with packed-bed.