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

摘要

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.