Chapter 10. Nanoparticles in the Water–Gas Shift Reaction and Steam Reforming Reactions

This chapter focuses on a discussion of the significance of metal particle size on catalyst activity and stability for the production of hydrogen as a clean energy carrier via reforming reactions, and in particular how the particle size can influence metal oxidation and carbon formation. Numerous catalysts based on noble metals such as rhodium, platinum, iridium, palladium and ruthenium, as well as on non-noble metals such as cobalt, nickel and copper, have been studied for methane reforming, steam reforming of ethanol and the water–gas shift reaction. The design of noble and non-noble metal nanoparticles as catalysts for the production of hydrogen at different operating conditions is analysed. Several reports are discussed taking into account how the catalytic activity of metal-based materials varies with respect to the particle size. In addition, the role of metal dispersion is related to the resistance to carbon deposition and oxidation of the reduced species under reaction conditions. Correlations between the specific activity and the metal nanoparticle size have been proposed. However, the catalytic activity and the selectivity to hydrogen are highly dependent on the metal–support interactions.