Chapter 4 - Steam Reforming for Fuel Cells

Abstract

This chapter deals with steam reforming. Steam reforming of hydrocarbons is a well-established process for the petrochemical industry and for refineries. The mechanism is understood at the atomic scale on the basis of recent fundamental studies including DFT calculations. The steam reforming of higher hydrocarbons is irreversible at the industrial reforming conditions. Steam reforming catalysts are typically based on nickel. The catalyst must ensure equal distribution of flow between the tubes in a tubular reformer and across the catalyst bed in an adiabatic reformer. It should be mechanically stable under all process conditions as well as conditions during start-up and shutdown of the reformer. Also, the shape of the catalyst pellet should be optimized to achieve maximum activity with minimum pressure drop. In order to fulfill the above-mentioned requirements to the catalyst, the particles are usually made of ceramic material of cylindrical shape with one or more internal holes. It is possible to steam-reform heavy distillates, provided they have been desulfurized. If not, sulfur accumulates on the pre-reformer catalyst and the sulfur capacity of the catalyst determines the life of the catalyst. Methanol and DME are easily converted by steam reforming, whereas it remains a challenge to find a stable catalyst for conversion of ethanol. The development of multichannel reformers has resulted in a significant process intensification contributing to low system costs.