In a concept green fab design, I have pyrolysis of (fractionated) cellulose feeding CVD to make CNT (metallic CNT, nonmetallic (semiconducting (*)) CNT, A-CNT, VACNT), or Methane, or CO2.

Now that there's a scholarly article describing creation of air filters and CO2 filters out of graphene, CO2 capture that yields high carbon graphene wafers would also be useful to feed to a pyrolysis reactor that feeds to CVD.

The model indicated that CVD from pyrolysis of cellulose biofeedstock would yield 33% metallic CNTs and 67% non-metallic CNTs, which are semiconducting.

In this concept design at present, I have Lignin and Phytic acid to contain the Carbon Nanotubes so that the CNTs are not hazardous to life if they enter soil or water or are burnt.

A research question for basic research with real world applications:

If lignin is not enough to make the inflamed CNTs char instead of ~aerosolize, is the phosphorous in phytic acid would encase the CNT in phosphorus and char.

This is apparently already an issue because CNTs are added to various products - like synthetic tires - and the CNTs are ~aerosolized if burnt.

For safety in a production process, this model (Gemini3Pro) suggests that all-liquid low-pressure lower-tempetature processing of CNT would help to minimize risk.

The 75% and the 3:1 ratio are not related. Methane has the formula CH4, so for 12 grams of carbon you have 4 grams of hydrogen. If you successfully break down the molecule CH4 you get a carbon-hydrogen ratio of 3:1. Now, let's say you start with 5.33 kg of methane. Only 75% gets converted, so that's 4 kg. Of that, you get 3 kg of carbon and 1 kg of hydrogen.

It extremely depends on the exact reactions. I'm not a chemist but AFAIK carbon nanotube production doesn't like taking in non-carbon atoms.

Things like crystallization reactions will produce very pure products, some other reactions will absorb more contaminants.

Yes, did you read it? Hydrogen and solid carbon, so the result is no greenhouse gas emissions.

It's clean, but it's still non-renewable. Oil companies have to keep finding ways to greenwash themselves.

Not sure what's wrong here. They said clean, not renewable right?

I'm a hardline no-fossi-fuels ever kind of guy and yes, this is clean energy.

If you collect the pollutants before emitting them and turn them into stable products, you aren't polluting.

Ergo, clean.

It has nothing to do with clean energy, other than the downstream effects of cheap CNTs should the process be refined enough to scale and commercialize. The hydrogen is recycled in the process. The primary thing that it produces are CNT aerogels. However according to the paper catalyst efficiency is shit. Says less than 0.1% of catalyst particles actually grew CNTs. No wonder CNTs are currently ≥$200/kg. Needs improvement by either dramatically increasing catalyst efficiency or finding dirt cheap iron/sulfur sources.

Carbon fouling is also a major block to scale. 15-20% of carbon deposits as soot on reactor walls. At a 1MW scale thats 15-30 kg/h of crud degrading the catalytic heat transfer. Continuous cleaning or scheduled downtime would drive OPEX out of possible realities.

Hot hydrogen loops are a son-of-a-bitch and equal continuous embrittlement of pipes, valves, pumps. Seals that work at temperature. H2 Leak detection. Some real heavyweight process safety engineering here.

The reactor chemistry is solved. The paper proves it works.

The scale-up is where clean-tech startups go to burn money and die.

That.. is the whole point of the reactor? It produces clean H2 to make it worthwhile as a clean fuel.

Currently H2 is clean only at the usage stage, not at the production stage. Just like electricity for EVs in Germany :)

Things take longer this time of year, and fake internet points never matter anyway.