Reminds me of a futurist I read years ago who was sure super critical water oxidation would solve all of our pollution problems. Ceramics are a “Pick two” material. You can handle heat, pressure or corrosion. SCWO requires all three. Some clever team invented composite ceramics trying to fix the problem, but that was a decade or two ago and still it’s a niche solution used for truly pernicious toxins and that’s about it, so I’m guessing it either didn’t work long term or was made out of unobtanium.