The trade-off
Electronic conduction that removes reaction heat short-circuits the ionic interfacial polarization the selectivity lever requires.
°C · bar · wt% · nm · m²/g · % conversion
Concepts considered
- Embedded two-phase / loop-heat-pipe cooling in a porous SiC wickKept
- Thin superprotonic proton layer as the ionic-lever mediumKept
- Electrochemical H-pump to dial the H₂:CO ratioKept
- Spatial domain separation (fuel-cell repeat-unit topology)Kept
- Conduction-only heat path (bulk β-SiC ± graphite)Dropped
- Electronic lever on conductive β-SiC / graphiteDropped
- Field-effect lever on bulk cobalt particlesDropped
Sources
- [1]
Selectivity control in cobalt Fischer-Tropsch is diffusion-limited above a critical particle size; sub-6 nm crystallites re-oxidize under reaction water partial pressure.
- [2]
Superprotonic solid acids conduct via a hydrogen-bond network that collapses on liquid-water contact — a stability window, not a stable material.
- [3]
Phosphoric-acid fuel-cell stacks operate on CO-bearing reformate at 180–210 °C with the acid immobilized in a silicon-carbide matrix.
How this could be wrong
- Strongest argument against
- The flagship design claims spatial separation resolves the heat-vs-lever contradiction — but that same separation strips the proton pump of authority. A discrete electrolyte band doses protons only to catalyst within a diffusion length, and the reaction consumes H₂ so fast the dose never reaches the bulk pore-distributed catalyst, so the dial steers ~1–5% of the inventory. Interdigitate the band to fix this and the ionic and heat paths re-collide — the contradiction is relocated, not solved.
- Prior art we might have missed
- The literature search covered solid-acid fuel cells but missed phosphoric-acid fuel cells — a 40-year industry running phosphate proton conductors on CO-bearing reformate at ~180–210 °C, holding the acid in a SiC matrix. That is a direct source for the two items flagged as "zero data" here: phosphate stability and CO tolerance in reducing gas.
- Physics assumptions to verify
- Load-bearing and untested: that faradaically-dosed hydrogen changes the H₂/CO the bulk catalyst sees, not just a shell at the electrolyte. The lever only homogenizes the disc if the Damköhler number Da ≲ 1, and fast H₂ consumption makes Da ≫ 1 likely. Test: apply current in a thin (<penetration depth) vs thick catalyst layer; if selectivity shifts only in thin layers, the full disc cannot be dialed.
- Domain-expert pushback
- A veteran solid-acid electrolyte engineer: "You put a water-soluble, creeping solid acid inside a reactor that makes liquid wax and threads a 30–40 bar water coolant loop through the same porous body. Your water analysis is vapor-only — yet condensed water at any cold spot, or one coolant leak, dissolves the electrolyte outright, and wax fouls the proton surface."
- What would change the recommendation
- If spatially-resolved sampling shows the faradaic H₂/CO shift decays within a sub-millimetre diffusion length so reactor-average selectivity moves <0.01 per A/cm², the proton pump cannot steer the bulk product — and we would prefer the two-phase-cooled, coarser-catalyst design with thermal zoning over the flagship stack, even if the electrolyte survives the syngas.