Hydrogen production via Sorption enhanced ethanol steam reforming process.

MENENDEZ, R. BELÉN; ALEMANY, LUIS; GRASCHINSKY, CECILIA; AMADEO, NORMA E.

Costa del Sol

Conferencia; European Hydrogen Energy Conference; 2018

The concept of hydrogen economy, in which it is considered as a carrier of energy in place of fossil fuels, has generated multiple research studies [1]. Hydrogen is presented as an environmentally sustainable alternative for energy production. In this context, hydrogen must be produced from renewable raw materials (biomass) such as bioethanol, glycerol, bio-oil through the steam reforming process. Thermodynamic studies have shown [2] that the steam reforming of ethanol is feasible at temperatures higher than 500 °C, being the main products: CH4, CO, CO2 and H2. In spite of the apparent simplicity of the reaction: C2H5OH + 3H2O ↔ 6H2 + 3CO2, ethanol steam reforming involves a complex system of reactions, so that selectivity and yield are limited by the equilibrium [3-5] of the water gas shift reaction (WGS): CO + H2O ↔ CO2 + H2 and the methane steam reforming reaction (MSR): CH4 + H2O ↔ CO + 3H2. In order to increase the production and selectivity to H2 it is proposed to integrate the reforming reaction with the selective separation of CO2 employing an adsorbent material, in a single stage, known as "sorption enhanced ethanol steam reforming" (SE-ESR) [6]. In this way, the equilibrium of the WGS reaction is modified according to the Le Chatelier principle [6-10] and increases the purity of H2 in the effluent. The SE-ESR process has an additional advantage and is that the heat generated in the gas-solid adsorption reaction (eg: CaO + CO2 ↔ CaCO3 ΔH = -176 kJ/mol) implies the possibility of operating the reforming at a lower temperature, with the consequent energy saving.This work reports sorption enhanced ethanol steam reforming experimental results from a fixed bed laboratory-scale reactor using NiMgAl HDL [11-12] as reforming catalyst and CaO as sorbent. It was studied the effect of sorbent/catalyst configuration, sorbent/catalyst mass ratio and reaction temperature. It was also analyzed the stability under different carbonation-calcination cycles.