Activity and characterization studies in methanol reforming catalysis: copper and copper-zinc oxide catalysts and the role of nanomaterials

Hydrogen storage is a major barrier to commercialization of proton exchange membrane (PEM) fuel cell powered automobiles. The problem can be circumvented by storing a liquid hydrogen source and then using a reforming reaction to generate hydrogen onboard the vehicle. Methanol is the preferred liquid hydrogen source for onboard generation. Methanol steam reforming is a convenient way to generate large amounts of clean hydrogen at reasonable temperatures and atmospheric pressure. Cu and CuO-ZnO reforming catalysts on Al2O 3, ZrO2/Al2O3, and CeO2/Al 2O3 nanoparticle oxide supports were investigated in this work. These systems ranged from traditional impregnated CuO-ZnO/Al2O 3 to more complex CuO-ZnO on mixed nanoparticle ZrO2/Al 2O3 supports. Finally, binary CuO/ZrO2 systems were constructed using a reverse microemulsion procedure.;Detailed reaction studies were performed and kinetic reaction data was examined and compared to surface, structural and electronic characterization data in order to determine both structural and valence state information of the catalyst system before and after reaction. In all cases it was determined that a reasonable Cu surface area is necessary to catalyze the reforming reaction but that high Cu surface area is not the critical criterion for highly active reforming catalysts. It was shown that using nanoparticle Al2O 3 supports can greatly increase catalyst surface area but that Al 2O3 has a retarding effect on catalytic activity which partially offsets any benefits. Therefore it was concluded that Al2O 3 should only be used in relatively low concentrations or in conjunction with another oxide support.;It was determined that an electron deficient Cu species formed due to an interaction with the nanoparticle ZrO2 support which was highly beneficial for catalyst performance. This electron deficient Cu species promoted the methanol reforming reaction while also apparently suppressing CO production via the reverse water gas shift. This work demonstrates that the Cu-ZrO 2 synergy can be exploited by using binary reforming catalysts and is increased by using calcination temperatures above 300°C, despite a slight loss of Cu surface area at high calcinations temperatures.