Optimization of hydrogen production with CO2 capture by autothermal chemical-looping reforming using different bioethanol purities

• Published in: Applied energy Vol. 169; pp. 491 - 498
• Main Authors: García-Díez, E., García-Labiano, F., de Diego, L.F., Abad, A., Gayán, P., Adánez, J., Ruíz, J.A.C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-05-2016
• Subjects: Bioethanol; Chemical-looping reforming; CO2 capture; Heat balance; Hydrogen production; Oxygen-carrier; Heat balance; Chemical-looping reforming; Bioethanol; Oxygen-carrier; CO2 capture; Hydrogen production
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2016.02.061

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•Autothermal-CLR and WGS have been considered for H2 production with CO2 capture.•Bioethanol was used as renewable fuel.•Mass and heat balances allow process optimization.•The use of diluted bioethanol implies energy saves in the bioethanol production.•The use of diluted bioethanol (52vol.%) produces 4.62mol H2/mol ethanol.
Autothermal Chemical-Looping Reforming (a-CLR) is a process which allows hydrogen production avoiding the environmental penalty of CO2 emission typically produced in other processes. The major advantage of this technology is that the heat needed for syngas production is generated by the process itself. The heat necessary for the endothermic reactions is supplied by a Ni-based oxygen-carrier (OC) circulating between two reactors: the air reactor (AR), where the OC is oxidized by air, and the fuel reactor (FR), where the fuel is converted to syngas. Other important advantage is that this process also allows the production of pure N2 in the AR outlet stream. A renewable fuel such as bioethanol was chosen in this work due to their increasing worldwide production and the current excess of this fuel presented by different countries.
In this work, mass and heat balances were done to determine the auto-thermal conditions that maximize H2 production, assuming that the product gas was in thermodynamic equilibrium. Three different types of bioethanol has been considered according to their ethanol purity; Dehydrated ethanol (≈100vol.%), hydrated ethanol (≈96vol.%), and diluted ethanol (≈52vol.%). It has been observed that the higher H2 production (4.62mol of H2 per mol of EtOH) has been obtained with the use of diluted ethanol and the surplus energy needed could be compensated by the energy save achieved during the purification of ethanol in the production process.