Sorption-Enhanced Steam Reforming of Ethanol: Thermodynamic Comparison of CO2 Sorbents

• Published in: Chemical engineering & technology 2012-05, Vol.35 (5), p.847-858
• Main Authors: Wu, Y. J., Díaz Alvarado, F., Santos, J. C., Gracia, F., Cunha, A. F., Rodrigues, A. E.
• Format: Article
• Language: English
• Subjects: Adsorption; Applied sciences; Chemical engineering; CO2 sorbents; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fuel cells; Sorption-enhanced steam reforming; Thermodynamics
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.201100534

A thermodynamic analysis is performed with a Gibbs free energy minimization method to compare the conventional steam reforming of ethanol (SRE) process and sorption‐enhanced SRE (SE‐SRE) with three different sorbents, namely, CaO, Li2ZrO3, and hydrotalcite‐like compounds (HTlc). As a result, the use of a CO2 adsorbent can enhance the hydrogen yield and provide a lower CO content in the product gas at the same time. The best performance of SE‐SRE is found to be at 500 °C with an HTlc sorbent. Nearly 6 moles hydrogen per mole ethanol can be produced, when the CO content in the vent stream is less than 10 ppm, so that the hydrogen produced via SE‐SRE with HTlc sorbents can be directly used for fuel cells. Higher pressures do not favor the overall SE‐SRE process due to lower yielding of hydrogen, although CO2 adsorption is enhanced. The current research status of thermodynamic analysis on ethanol steam reforming (SRE) and sorption‐enhanced SRE (SE‐SRE) is surveyed. Hydrotalcite‐like compounds (HTlc), CaO, and Li2ZrO3 as three typical CO2 sorbents for SE‐SRE are compared for the first time. The simulated results agree well with other publications.