Work

On the Applicability of Iron-Based Oxygen Carriers and Biomass-Based Syngas for Chemical Looping Hydrogen Production

Year: 2024

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The chemical looping hydrogen (CLH) production process typically uses iron-based oxygen carrier materials and can provide hydrogen with high purity. Chemical looping is particularly attractive when renewable fuels like syngas from biomass gasifiers are used. This work provides a novel assessment of the possible thermodynamic and kinetic limitations for iron-based oxygen carriers in CLH fueled by biomass-based syngas, with a detailed study employing synthetic ilmenite (Fe 2 O 3 + TiO 2 ). Its phase diagram with H 2 /H 2 O- or CO/CO 2 -mixtures was compared to the typical Baur–Glaessner diagram for iron oxides. Thermogravimetric analyses underlined the necessity to consider TiO 2 as a chemically active component for this material, in contrast to the common simplification of inert support materials. The validated phase diagram predicted stringent fuel limitations concerning H 2 O- or CO 2 -contents. This was confirmed by feeding a real biomass-based syngas, provided by a lab-scale gasifier, to a fixed bed CLH reactor. It was demonstrated for the H 2 /H 2 O-system that removing the oxidizing agent from the feed gas helps to overcome these limitations. Kinetic limitations within the thermodynamic boundaries were investigated using a recently published multiscale model for the H 2 /H 2 O-system. The influence of the fuel’s reduction potential on reaction rates was explored to formulate simple, kinetic design criteria. A significant retardation of conversion rate in the vicinity of the equilibrium was indicated, effectively narrowing the feasible composition range. Recommendations for the application of biomass-based syngas with iron-based oxygen carrier materials were provided.

Source: Energy & Fuels

DOI: 10.1021/acs.energyfuels.4c03137

Authors: Thomas Steiner, Lukas von Berg, Andrés Anca-Couce, Kai Schulze

Institutions: Graz University of Technology, BEST - Bioenergy and Sustainable Technologies (Austria), Universidad Carlos III de Madrid

Language: English

Topic: Chemical Looping and Thermochemical Processes

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Affordable and clean energy, Responsible consumption and production

Open Access status: hybrid

Estimated APC paid: $4,500