(563d) Steam-Methane Reforming on Joule Heated Ni-Coated Metal Wires

One potential low-carbon solution for SMR is electrifying the heating process using renewable power from sources such as wind and solar that do not emit GHG. Interesting approaches exist that utilize electricity to energize chemical reactors. Active research efforts are reported for e-SMR, although there are still no current industrial-scale processes. In this study we investigate the application of Joule heating of catalyst-coated, high-resistance FeCrAl wires as a potential method to electrify SMR.

The coating of Ni/ZrO₂ and Ni/Al₂O₃ onto 0.5-mm diameter FeCrAl wires involves slurry synthesis and coating steps. A wet impregnation procedure is used to synthesize the catalysts with two different Ni loadings (10 and 20 wt%). Slurries prepared with catalyst powders are uniformly deposited as a thin film onto coiled and straight FeCrAl wires. Joule heating of bench-scale reactor experiments are conducted by applying direct electric current through single wire and multiple wires. The feed gas is a mixture containing 5.4 vol% CH₄ with excess steam (H₂O:CH₄ = 3:1 – 4:1) molar ratio. This feed gas is kept at 190°C and atmospheric pressure and flows into a stainless-steel tube housing the wire. FTIR analysis is used to measure the effluent CO, CO₂, and CH₄ concentrations.

Major highlights: (a) SEM/EDS analysis reveal uniform coating of Ni/ZrO₂ or Ni/Al₂O₃ on FeCrAl wires; (b) CH₄ conversion is higher on Ni-coated wire compared to uncoated or ZrO₂/Al₂O₃-coated wire; (c) Discontinuous jump in CH₄ conversion at a critical applied power; (d) CH₄ conversion is higher on Joule heated wire compared to conventionally-heated wire; and (e) Stability experiments reveal that the catalyst-coated wires exhibited sustained activity, clearly demonstrating sustained SMR for several hours without catalyst deactivation. Several mechanisms are examined to elucidate the impact of Joule heating and the interesting differences between Joule and conventional heating through targeted experiments and reactor modeling.