STEAM REFORMING OF HYDROCARBONS.

The object of this chapter is to review critically the literature on the steam reforming of hydrocarbons. The thermodynamics of reactions are discussed; the production of CO, CO//2, and H//2 is favored at high temperatures whereas CH//4 production is favored at lower temperatures. Two distinct uses of the process are therefore encountered: (i) the high temperature process ( greater than ca. 1000 K), for the manufacture of H//2 or CO-H//2 mixtures; and (ii) the production of methane-rich gases either as a Towns' Gas or as Substitute Natural Gas, carried out at lower temperatures less than ca. 800 K). These two uses require distinctly different types of catalyst, the first requiring a much more robust material than the second. The development of these processes and the formulation of the catalysts are discussed, together with some ideas on the nature of the active sites. A section is concerned with the mechanism of the reaction and an attempt is made there to relate investigations of its selectivity to the results of kinetic measurements and also to detailed mechanistic studies. Finally, the paper deals briefly with poisoning of steam reforming catalysts, with the technically important problem of carbon deposition (coking), and with catalyst sintering.