The Steam Reforming of Hydrocarbons

This chapter is concerned with the work reported in the literature on the steam reforming df hydrocarbons which has been done since 1974 when the earlier review by Ross was written. For continuity some reference has had to be made to research covered in that review and some work before 1974 not described there is included here. Hydrocarbon steam reforming is still a process of major importance for the manufacture of hydrogen, synthesis gases, and town gas and, in the last five years, for the production of substitute natural gas. The study of reactions between hydrocarbon and steam on catalytic surfaces has continued to be an area of interest, throwing light on the mechanism of hydrocarbon decomposition and on the properties, of metal surfaces. 

After a short review of recent process developments, the most important work on the formulation and performance of reforming catalysts, and then on the mechanism and kinetics of hydrocarbon-steam reactions, is described. The reactivity of different hydrocarbons and the reforming of higher boiling point hydrocarbons is considered. The next section deals with carbon formation and finally relevant patents filed since 1973 are briefly described. 

The following reactions will be referred to in this review. The hydrocarbon-decomposition reactions producing H2, CO, CO2, and CH4 may be  

The products of these endothermic reactions, which are not necessarily primary products, can be equilibrated by the water-gas shift reaction (4) and methane-steam reactions (5) and (6)  

Ross in Surface and Defect Properties of Solids , ed. M. W. Roberts and J. M. Thomas (Specialist Periodical Reports), The Chemical Society, London, 1974, Vol. 4, p. 34. 

---

In the production of hydrogen by the steam reforming of hydrocarbons, the classic water-gas reaction is used to convert CO in the gases leaving the reforming furnace to hydrogen, in a shift converter. 

The results for the effect of alkali are interesting in connection with the type of catalysts which have been used commercially for the steam reforming of hydrocarbons.2 64 The original commercial materials were carefully... 

The steam reforming of hydrocarbons is in principle a reduction of water with the carbon of the organic starting material. In the case ofmethane, / of the hydrogen is supplied by water. This share increases with the higher hydrocarbons. Other reactions that proceed at the same time as the reforming... 

Dihydrogen is an important industrial chemical, mostly made from the steam reforming of hydrocarbons from petroleum and natural gas. The simplest of these reactions,... 

Induction period of coking in the steam reforming of hydrocarbons... 

The length of the induction period is affected by all the same factors which affect the coking rate of nickel catalysts in the steam reforming of hydrocarbons. A high dispersion of nickel, an increase in MgO content in the support or a small additive of a promoter all cause a prolongation of the induction time. 

Hydrogen is also manufactured industrially by direct electrolysis of H20, HF, and 22 to 25 percent hydrochloric acid (HC1). However, the hydrogen produced by electrolysis accounts for a small percentage of the total H2 production (see Table 22.7). In contrast to the steam reforming of hydrocarbons, the hydrogen from electrolysis is very pure (>99 vol%) which eliminates the costly purification steps. 

Dihydrogen (bp 20.28 K) is a colorless, odorless gas virtually insoluble in water. It is made industrially by the steam reforming of hydrocarbons, notably methane... 

The general overall reaction for the steam reforming of hydrocarbons can be formulated as (40) ... 

Clarke, S., Dicks, A., Pointon, K., Smith, T., Swann, A. (1997). Catalytic aspects of the steam reforming of hydrocarbons in internal reformiing fuel cells. Catalysis Today 38,411-423. 

The steam reforming of hydrocarbon feedstocks is a common industrial process which produces hydrogen for use in methanol or ammonia synthesis. A variety of hydrocarbons, e.g. natural gas or naphthas, can be used as the reactant in the steam reforming process, This use of a variety of reactant feed types places considerable demands upon the catalyst manufacturer since all hydrocarbons have different reactivities and, most importantly, disparate tendencies to generate carbonaceous deposits, ICI produce a range of catalysts for use with a number of hydrocarbon reactants. For the reforming of heavy naphtha feedstocks, which show a considerable propensity for carbon deposition, ICI provides a potassium promoted nickel based catalyst (ref 1). The object of this paper is to describe the mechanism by which alkali provides resistance to carbon formation in nickel catalysts. 

Carbon formation and catalyst deactivation have also been observed in the SRE. Approaches similar to those discussed above for the steam reforming of hydrocarbons are also employed to suppress the carbon formation in ethanol reforming as well.1 7... 

Borowiecki, T., Golebiowski, A., and Stasinska, B. Effects of small Mo03 additions on the properties of nickel catalysts for the steam reforming of hydrocarbons. Applied Catalysis. A, General, 1997, 153 (1-2), 141. 

One of the most important reactions to produce syn-gas is the steam reforming of hydrocarbons. The reactions involved in this process are the following ... 

Iron, nickel, cobalt, and their alloys are the most studied metals for the catalytic growth of CNFs or CNTs. The readiness of these metals to produce metal-carbon solid solutions and to form metastable carbides in the appropriate reaction temperature range should be an important factor to take into account for the comprehension of their reactivity. The different carbon species formed depending on the temperature range employed in the steam reforming of hydrocarbons on nickel catalysts have been discussed [29] and consist of ... 

Synthesis gas, primarily methane and hydrogen, produced by the steam reforming of hydrocarbons still contains about 0.5 mol% CO2 after... 

The origins, type, form, and reactivity of surface carbonaceous deposits, formed during the steam reforming of hydrocarbons, was the subject of a paper by Jackson et al Pulses of [14-C]labelled aromatic or aliphatic... 

As long-chain hydrocarbons are more reactive than CH4, the steam reforming reaction of liquid hydrocarbons is less endothermic than CH4. Since aromatics are more stable than paraffins, their reactivity towards steam approaches that of GH4. For many years, nickel has been the most suitable metal for the steam reforming of hydrocarbons, because the TOF values for the reaction are very... 

The steam reforming of hydrocarbons such as diesel has been demonstrated in MSRs whose mechanical stability has been proven at high temperature (750-850 °C). Most of the configurations consist of co-current flow diesel steam reforming combined with combustion of fuel cell anode and/or cathode off-gas surrogate. Full conversion was obtained in all cases. Power equivalent of these systems varied between 2-5 kW thermal energy of the hydrogen produced and 10 kW thermal input of the diesel feed [4,73]. However, the most advanced... 

---