CoorsTek (Norway)

In this work, impedance spectroscopy has been employed to explore the electrochemical behaviour of a 15 cm2 complete tubular cell with BaZr0.8Ce0.1Y0.1O3-δ (BZCY) electrolyte and two asymmetric Ni-BCZY cermet electrodes for hydrogen separation. Analyses of impedance spectra at different temperatures and gas compositions reveal that the thick inner electrode contributes most to the total polarisation resistance (Rp). For Rp there are four contributions with well-separated time constants of which gas phase hydrogen diffusion within the porous Ni-BZCY anode is predominant. The other three can be ascribed to proton migration through the space charge layer of the BZCY electrolyte adjacent to the Ni electrode, hydrogen redox charge transfer reactions, and hydrogen diffusion within Ni bulk. The present study guides the way to parameterise and, on this basis, optimise electrodes for scalable proton ceramic electrochemical cells.

Conventional production of hydrogen requires large industrial plants to minimize energy losses and capital costs associated with steam reforming, water–gas shift, product separation and compression. Here we present a protonic membrane reformer (PMR) that produces high-purity hydrogen from steam methane reforming in a single-stage process with near-zero energy loss. We use a BaZrO3-based proton-conducting electrolyte deposited as a dense film on a porous Ni composite electrode with dual function as a reforming catalyst. At 800 °C, we achieve full methane conversion by removing 99% of the formed hydrogen, which is simultaneously compressed electrochemically up to 50 bar. A thermally balanced operation regime is achieved by coupling several thermo-chemical processes. Modelling of a small-scale (10 kg H2 day−1) hydrogen plant reveals an overall energy efficiency of >87%. The results suggest that future declining electricity prices could make PMRs a competitive alternative for industrial-scale hydrogen plants integrating CO2 capture.

This paper presents an experimental and modeling study of methane dehydroaromatization (MDA) chemistry using a bifunctional 6 wt % Mo/HZSM-5 catalyst in an isothermal laboratory-scale packed-bed configuration. The reported measurements include methane conversion and product yields and selectivities as a function of temperature and flow rates (space velocity). The modeling is particularly concerned with developing and validating a microscopically reversible 54-step detailed reaction mechanism. The reaction mechanism is validated via direct comparison with the measured packed-bed performance. Although the operating conditions for the measurements are relatively limited, the detailed reaction mechanism is expected to have much wider predictive capability.