New Reactor Produces Clean Energy and Carbon Nanotubes From Natural Gas

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 scholarly article describing creation of air filters and CO2 filters out of graphene, a CO2 capture that yields high carbon graphene wafers would also be useful to bee 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.

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.

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.

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

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

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 :)

Could be the time of day?

dupe: https://news.ycombinator.com/item?id=46368776

It didn't show any matching posts when I shared the URL.

ENH: HN: search for matching articles on debounced update to the submit URL field

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

I think in HN terms "dupe" means a story which was on front page for some time and got some discussion, just a previous submission with few upvotes and no comments doesn't count as a dupe if it's clear it hardly can get on front page now (older than n hours).

Let's look at the numbers. The energy to split one mole of CH4 (i.e. 16 grams) into C and 2H2 is 74.6 kJ. If you burn that carbon you get 393.5 kJ and if you burn the hydrogen you get 483.6 kJ [1].

> And the energy content of the hydrogen output is less than the methane input plus the heat dumped in. This is thermodynamics.

You are right, but you forgot something. You are not creating the methane. You are extracting it from the ground. The energy content of the hydrogen is only 60% of the energy content of the methane you use to get it, and if you account for the energy to split the CH4, you are left with only 50% of the original energy of the methane. But then you get hydrogen that can generate emissions-free electricity. It's a good trade off.

[1] https://en.wikipedia.org/wiki/Standard_enthalpy_of_formation...

Sure but if you attached a hydrogen burner would it be net positive?

Then wouldn’t you have a cleaner energy system then burning the methane directly?