Challenges in the Steam Reforming Process

The steam reforming catalyst is very robust but is threatened by carbon deposition. As indicated in Fig. 8.1, several reactions may lead to carbon (graphite), which accumulates on the catalyst. In general the probability of carbon formation increases with decreasing oxidation potential, i.e. lower steam content (which may be desirable for economic reasons). The electron micrograph in Fig. 8.4 dramatically illustrates how carbon formation may disintegrate a catalyst and cause plugging of a reactor bed. 

This process of filament growth is closely related to the synthesis of single walled carbon nano-tubes. Here the aim is to selectively produce a single layer of carbon in a tube that is as long as possible. Owing to their extreme mechanical strength and interesting electronic behavior these materials have recently attracted substantial interest in materials science. 

It is important to note that the selectivity of sulfur-passivated catalysts towards steam reforming is greatly enhanced because carbon formation is effectively suppressed. The decrease in activity can to largely be compensated for by selecting inherently more active catalysts and by operating at higher temperatures. Unfortun- 

Cold-Nickel Alloy Catalysts for Steam Reforming 

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