Steam reforming of ethanol

Garcia, E. Y. Laborde, M. A., Hydrogen production by the steam reforming of ethanol Thermodynamic analysis. International Journal of Hydrogen Energy 1991,16(5), 307-312. 

Vasudeva, K. Mitra, N. Umasankar, P. Dhingra, S. C., Steam reforming of ethanol for hydrogen production. International Journal of Hydrogen Energy 1996,21(1), 13-18. 

Fishtik, I. Alexander, A. Datta, R. Geana, D., A thermodynamic analysis of hydrogen production by steam reforming of ethanol via response reactions. International Journal of Hydrogen Energy 2000,25, 31-45. 

Table 1 Non-noble metal-based catalysts employed in the steam reforming of ethanol (SRE) for hydrogen production... 

Thus, the thermodynamic analysis suggests that the steam reforming of ethanol into H2 and C02 is thermodynamically feasible above 200 °C. A mixture of H2, C02, CO and CH4 will be produced at lower temperatures, below 400 °C. The CH4 formed will be subsequently reformed into syngas at higher temperatures, above 650 °C. 

Fig. 7 Thermodynamic equilibrium compositions on dry basis for the steam reforming of ethanol. All species are in gas phase. Initial concentrations of CO, CH4, CH3CHO are taken as zero in the calculation.

Table 4 Selected best performing catalysts for the middle-, and high-temperature steam reforming of ethanol (SRE) reaction"...

Table 5 Kinetic data of the steam reforming of ethanol over various supported Ni catalysts...

Among three different reforming processes discussed above, the steam reforming of ethanol yields more H2 in the reformate, 6 moles per mole of ethanol converted because the process extracts about 3 moles of H2 from water. This makes the process more attractive in terms of power generation via fuel cells. Assuming only 60% efficiency of a fuel cell, an useful electrical work output of about 12 828 kJ could be obtained from 1 liter of ethanol via steam reforming, which is about 3 times higher... 

Fig. 14 Mechanistic model for the carbon scavenging activity of stable Ni/La203 catalyst employed in the steam reforming of ethanol for H2 production.67...

This review analyzed the chemistry involved, thermodynamics, catalysts used, reaction pathways and mechanisms of various reforming techniques reported for the conversion of ethanol into H2-rich gas. The known reforming processes are broadly classified into three categories, namely steam reforming of ethanol (SRE), partial oxidation of ethanol (POE) and oxidative steam reforming (OSR)/autothermal reforming of ethanol. All these reactions are thermodynamically favorable even at lower temperatures, above 200 °C. 

Steam Reforming of Ethanol Even though all the samples containing 20 wt.% or above of Ni exhibited similar activity and selectivity (Table 11.6), their stability over a 500 h duration run varied sample 6A, with 40% Ni and a Ce02/Zr02 ratio of 1 was the most stable. The Ce/Zr ratio has a marked effect on the catalytic stability of these materials. 

D. Srinivas, C. V. V. Satyanarayana, H. S. Poddar, and P. Ratnasamy, Structural studies on NiO-Ce02—Zr02 catalysts for steam reforming of ethanol, Appl. Catal. A General 246, 323—334 (2003). 

Cobalt-based catalysts are effective in the ethanol reformation to hydrogen. Many oxides have been used to prepare supported cobalt catalysts of low cobalt content (circa 1 wt%) by impregnation from a solution of Co2(CO)8 catalysts were used in the ethanol reformation as prepared [156]. The performance of the catalysts in the steam reforming of ethanol was related with the presence, under reaction conditions, of metallic (ferromagnetic) cobalt particles and oxidized cobalt species. An easy exchange between small metallic cobalt particles and oxidized cobalt species was found. Comparison of Co/ZnO catalysts prepared from Co2(CO)8 or from nitrate precursor indicated that the catalyst prepared from the carbonyl precursor was highly stable and more selective for the production of CO-free hydrogen... 

Ethanol can be converted directly to hydrogen through two main processes, steam reforming of ethanol (SRE) and partial oxidation of ethanol (POE). These two reforming techniques are described by the following equations ... 

Figure 6.5 Reaction pathways for steam reforming of ethanol.

Ethanol is a natural renewable product normally produced from biomass, which is an important factor for near-zero carbon dioxide (C02) emissions. It is accessible, easy to transport, ecofriendly, nontoxic, and it can be transformed by catalytic reactions into hydrogen, which is important for fuel cell fuel processing [151], Section 9.8.10 discusses different processes for hydrogen production by the steam-reforming of ethanol. 

Table 2.26. Non-Noble Metal-Based Catalysts Employed in the Steam Reforming of Ethanol (SRE) for Hydrogen Production... 

Table 2.28. Selected Best Performing Catalysts for the Low-Temperature Steam Reforming of Ethanol (SRE) Reaction1...

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