Electrified methane reforming:Elucidating transient phenomena

Increasing implementation of renewable energy requires an infrastructure compatible with the intermittent production of green electricity. Herein we show the flexibility of electrically heated steam methane reforming with integrated ohmic heating, through a combination of CFD modelling and lab scale reactor tests. It is shown how start-up from an idle state to operation conditions can be achieved with instantaneous application of the full power required for a steady state conversion of 80%, with initial heating rates exceeding 50 °C/min. The initial heating rate is correlated to the thermal mass of the reactor, with the endothermic reaction governing the temperature profile. Cyclical operation displays no apparent delay between the change in temperature and methane conversion. The highest thermal gradient across the washcoat is predicted at steady state, with no increase during start-up despite the higher heating rates. The highest risk of carbon formation is predicted at the inlet at steady state operation. A temporarily peak in the equilibrated carbon potential is predicted near the outlet during start-up and shutdown between 500 and 600 °C, governed by the thermodynamics of the feed composition. Integrated ohmic heating supports steam methane reforming scalable to industrial conditions, operating closer to thermodynamic limits for carbon formation, and potentially based on the access to intermittent excess of renewable energy.</p

Retrofittable plug-flow reactor for in situ high-temperature vibrating sample magnetometry with well-controlled gas atmospheres

We have developed an in situ sample-holder—akin to a quartz-based plug-flow reactor—for vibrating sample magnetometry (VSM) in gas-controlled environments at ambient pressure and temperatures up to ∼1000 °C. The holder matches onto a specific type of vibrating sample magnetometer (Lake Shore model 7404-S), but the principles are applicable to other types of VSM. The holder has been tested on powder samples of Co particles on a MgAl2O4 support in both reducing and oxidizing atmospheres. The results show control of gas composition and sample reduction/oxidation. In comparison with conventional sample cups, the in situ holder shows a similar measurement sensitivity but a better repeatability due to the well-controlled gas atmosphere. Moreover, the in situ holder uses a closed gas tubing system such that the active gas only passes by the sample and it is not in contact with the VSM and oven parts. At the outlet, the gas can be collected for analysis and safe handling

Direct Hysteresis Heating of Catalytically Active Ni–Co Nanoparticles as Steam Reforming Catalyst

We demonstrated a proof-of-concept catalytic steam reforming flow reactor system heated only by supported magnetic nickel–cobalt nanoparticles in an oscillating magnetic field. The heat transfer was facilitated by the hysteresis heating in the nickel–cobalt nanoparticles alone. This produced a sufficient power input to equilibrate the reaction at above 780 °C with more than 98% conversion of methane. The high conversion of methane indicated that Co-rich nanoparticles with a high Curie temperature provide sufficient heat to enable the endothermic reaction, with the catalytic activity facilitated by the Ni content in the nanoparticles. The magnetic hysteresis losses obtained from temperature-dependent hysteresis measurements were found to correlate well with the heat generation in the system. The direct heating of the catalytic system provides a fast heat transfer and thereby overcomes the heat-transfer limitation of the industrial-scale steam reformer. This could consequently enable a more compact steam reformer design