Reforming ethanol steam

Ethanol steam reforming (ESR), that is, the reaction between ethanol and water, yields CO, CO2, and H2 according to the following reactions  

However, other reactions may occur, either from ethanol alone or by reaction between ethanol and reaction products (e.g., CO, CO2, and H2), as for example  

Finally, products may react together, as for example the reactions between CO or CO2 and Hz, yielding CH4 (methanation reaction) or between two CO yielding CO2 and C (CO disproportionation reaction or Boudouard reaction). Thus, ethanol steam reforming gives rise to many reactions that are difficult to discriminate. However, it was shown that CO and CH4 are primary products, formed by ethanol cracking, which are then converted by water-gas shift reaction (reaction (24.3)) and methane steam reforming reaction [5]. 

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Ethanol can be derived from biomass by means of acidic/enzymatic hydrolysis or also by thermochemical conversion and subsequent enzymatic ethanol formation. Likewise for methanol, hydrogen can be produced from ethanol with the ease of storage/transportation and an additional advantage of its nontoxicity. Apart from thermodynamic studies on hydrogen from ethanol steam reforming,117-119 catalytic reaction studies were also performed on this reaction using Ni-Cu-Cr catalysts,120 Ni-Cu-K alumina-supported catalysts,121 Cu-Zn alumina-supported catalysts,122,123 Ca-Zn alumina-supported catalysts,122 and Ni-Cu silica-supported catalysts.123... 

Cavallaro, S. Freni, S., Ethanol steam reforming in a molten carbonate fuel cell. A preliminary kinetic investigation. International Journal of Hydrogen Energy 1996, 21, 465-469. 

Catalysts were prepared by incipient wetness impregnation of commercial supports using cobalt nitrate as a precursor. Metallic cobalt species were active centers in the ethanol steam reforming. Over 90% EtOH conversion achieved. Nature of support influences the type of byproduct formation. Ethylene, methane and CO are formed over Co supported on A1203, Si02 and MgO, respectively... 

The thermodynamic analysis of loannides [193] on SRE in a solid polymer fuel cell indicated that the ethanol steam reforming reaction needs to be carried out in two steps a high-temperature endothermic step (steam reforming), in which ethanol is converted to a gaseous mixtures of H2, CO, CO2, CH4 and unreacted H2O, and a subsequent, low-temperature step (WGSR) in which CO reacts with water to form H2 and CO2. 

Recently, Comas et al.219 performed the thermodynamic analysis of the SRE reaction in the presence of CaO as a C02 sorbent. The equilibrium calculations indicate that the presence of CaO in the ethanol steam reforming reactor enhances the H2 yield while reducing the CO concentrations in the outlet of the reformer. Furthermore, the temperature range at which maximum H2 yield could be obtained also shifts from above 700 °C for the conventional steam reforming reaction without CaO to below 700 °C, typically around 500 °C in the presence of CaO. It appears that the presence of CaO along with ethanol reforming catalyst shift the WGS equilibrium in the forward direction and converts more CO into C02 that will be simultaneously removed by CaO by adsorption. 

Comas, J., Dieuzeide, M.L., Baronetti, G., Laborde, M., and Amadeo, N. Methane steam reforming and ethanol steam reforming using a Ni(II)-Al(III) catalyst prepared from lamellar double hydroxides. Chemical Engineering Journal, 2006, 118 (1-2), 11. 

Benito, M., Sanz, J.L., Isabel, R., Padilla, R., Arjona, R., and Daza, L. Bio-ethanol steam reforming Insights on the mechanism for hydrogen production. Journal of Power Sources, 2005, 151, 11. 

Llorca, J., Homs, N., Sales, J., and de la Piscina, PR. Efficient production of hydrogen over supported cobalt catalysts from ethanol steam reforming. Journal of Catalysis, 2002, 209 (2), 306. 

Aupretre, F., Descorme, C., Duprez, D., Casanave, D., and Uzio, D. Ethanol steam reforming over MgxNi1.xAl203 spinel oxide-supported Rh catalysts. Journal of Catalysis, 2005, 233 (2), 464. 

Cavallaro, S. Ethanol steam reforming on Rh/Al203 catalysts. Energy Fuels, 2000, 14 (6), 1195. 

Therdthianwong, A., Sakulkoakiet, T., and Therdthianwong, S. Hydrogen production by catalytic ethanol steam reforming. Science Asia, 2001 27, 193. 

We tested BaRhxZr(i.x)03 (5 wt.% Rh) for ethanol steam reforming [13] finding that an almost complete ethanol conversion (99.7%) was achieved at reasonably low temperature (550°C) with a hydrogen selectivity of roughly 68 mol%. Best catalytic performances were exhibited by the sample calcined at higher temperature (900°C), and this was again attributed to the more pure perovskitic structure, with better Rh interspersion. 

These systems were tested in several catalytic reactions, giving promising results for methane rich combustion and ethanol steam reforming (BaRhxZr(i. x)03), and for methane lean combustion (BaPdxZr(i x)03). 

P-23 - Cu-Y zeolite catalysts for methanol and ethanol steam reforming... 

Llorca et developed a micro-channel reactor where ethanol steam reforming is performed on one side of the plate while ethanol combustion is performed on the with 14 microchannels. The results revealed that Rh-based catalysts exhibited the highest catalytic activity, when compared to Co and Ni. The Rh-Ni-Ce catalyst was operated for 100 h without any noticeable degradation in activity and selectivity. Full conversion was achieved for the entire period and the Hg selectivity was 86%. The CO content in reformate remained constant ca. 8.2%. 

Llorca et developed a microchannel reactor where ethanol steam reforming is performed on one side of the plate while ethanol... 

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