Oxidative reforming of ethanol

Steam and oxidative reforming of ethanol and methane were tested through a two-step process, in which the multitube was coupled to a traditional reformer operating at high temperature. The experimental apparatus is shown in Figure 13.45 [82,84,86,103-105]. Such a process maximized the reaction yield and reduced the permeation area required for separating the hydrogen produced [75,106]. 

Oxidative Steam Reforming (OSR) / Autothermal Reforming of Ethanol... 

Oxidative steam reforming/autothermal reforming of ethanol... 

Fig. 11 Free energy changes in the oxidative steam reforming/autothermal reforming of ethanol, acetaldehyde and methane.

Fig. 12 Thermodynamic equilibrium compositions on dry basis for the oxidative steam reforming of ethanol. All species are in gas phase. Initial concentrations of CO, CH4, CH3CHO are taken as zero in the calculation.

Table 7 References on oxidative steam reforming (OSR) and autothermal reforming of ethanol for hydrogen production... 

Scheme 6 Proposed reaction pathway for the oxidative steam reforming/ autothermal reforming of ethanol. The dehydration into ethylene intermediate followed by ethylene reforming are not shown. 

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. 

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 2.29. H2 and CO selectivities in the oxidative steam reforming/autothermal reforming of ethanol over selected catalysts. Data reported at complete conversion of ethanol and obtained using 02/EtOH = 0.36, H20/EtOH = 2.28, and P = I atm and calculated by including CH4 (solid lines) and excluding CH4 (broken lines) in the calculations. Catalysts (a) Pd/ZnO, (b) NiRh/Ce02, (c) Ru/A1203,...

Kugai, J., Subramani, V., Song, C., Engelhard, M.H., and Chin, Y.-H. Effects of nanocrystalline Ce02 supports on the properties and performance of Ni-Rh bimetallic catalyst for oxidative steam reforming of ethanol. Journal of Catalysis, 2006, 238 (2), 430. 

Fierro, V., Klouz, V., Akdim, O., and Mirodatos, C. Oxidative reforming of biomass derived ethanol for hydrogen production in fuel cell applications. Catalysis Today, 2002, 75 (1—4), 141. 

Velu, S., Satoh, N., Gopinath, C.S., and Suzuki, K. Oxidative reforming of bio-ethanol over CuNiZnAl mixed oxide catalysts for hydrogen production. Catalysis Letters, 2002, 82, 145. 

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