On 27/02/2025 13:59, Jeff Layman wrote:

Fig.1d has a reaction at the top:
CO2 + 2H+  -->  CO + H2 (H2O)
What does the 2H+ signify on the LHS of the equation? What does the H2O
in brackets mean?

Any clarification gratefully received.

It's Ecobollox. It's done by Magic.
--
"I am inclined to tell the truth and dislike people who lie consistently.
This makes me unfit for the company of people of a Left persuasion, and
all women"

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On 27/02/2025 23:23, Paul wrote:

On Thu, 2/27/2025 11:54 AM, Tim Streater wrote:

On 27 Feb 2025 at 16:32:37 GMT, "Tim Streater" <tim@streater.me.uk> wrote: >>

On 27 Feb 2025 at 13:59:46 GMT, "Jeff Layman" <Jeff@invalid.invalid> wrote: >>>

On 27/02/2025 12:36, Theo wrote:

The Natural Philosopher <tnp@invalid.invalid> wrote:

On 27/02/2025 11:16, Jethro_uk wrote:

https://eastangliabylines.co.uk/science/sunlight-to-fuel-cambridges-new-
breakthrough-in-clean-energy/

Why not use plants instead?

Plants take a lot of effort and inputs (land, fertiliser, water) to grow. >>>>> Then you need to process them into something useful.

Being able to skip those steps has a lot of advantages. At the end of the >>>>> day it's all about efficiency numbers - remains to be seen how far this >>>>> could go in efficiency terms, and whether there are cases where it would >>>>> make sense where you don't have those inputs.

The paper is here:
https://www.nature.com/articles/s41560-025-01714-y

I seem to be misunderstanding something in that article. Syngas is a
mixture of carbon monoxide and hydrogen. Where does the hydrogen come
from? Fig.1a shows just air entering the reaction chamber. There is no >>>> mention of hydrogen at all (no green dots).

Fig1.b shows Air/N2 entering the reaction chamber. The "CO2U Unit"
(light red) is shown as containing hydrogen as it has green dots. Where >>>> does that hydrogen come from? In Fig1.a the "CO2U Unit" is not shown as >>>> containing any hydrogen.

Fig.1d has a reaction at the top:
CO2 + 2H+ --> CO + H2 (H2O)
What does the 2H+ signify on the LHS of the equation? What does the H2O >>>> in brackets mean?

Well I dunno for sure. But the reaction seems to be taking place over a
substrate of glycolaldehyde (HOCH2−CHO) and other substances. Perhaps with an
input on sunlght (UV?) it catalyses the breakdown of the glycolaldehyde: >>>
HOCH2−CHO -> 2CO + 2H2

but I'm just guessing. Do we have a real chemical engineer on the strength? >>

OK - belay that. The actual substrate seems to be mineral only, no organics. >> The glycolaldehyde and the formate appear to be outputs, not inputs.

I can suggest this much.

It's a Redox reaction.

There are two equations, one is a reduction, one is an oxidation.

The PET and Ethylene Glycol is an attempt to clean up an industrial pollutant, via using it as part of a half reaction. The "value added chemical"
notion, is the outputs are somehow easier to deal with. The glycol aldehyde dimer
is supposed to be a simple sugar.

In normal chemistry notation, one of the reactions
contributes something to the other reaction.

But attempts to get anything to balance, to have a net H2 output
for the Syngas, haven't worked out for me. Normally, you would
need some H2 to make a Syngas, but there is no source of gaseous H2
in the chamber.

The next stage after the making of Syngas, might be
something like this. This could make longer chain hydrocarbons
which are easier to store on site. Perhaps in a liquid form.
The industrial version of this, needs energy input. Looking
for a photochemsitry version, is to harvest the energy from the Sun.

"Photo-driven Fischer–Tropsch"

https://pubs.rsc.org/en/content/articlelanding/2020/ta/d0ta09097b

After reading several papers today, my conclusion is that everyone
is sloppy when writing these papers.

I'm replying to this, your other comments, and Nib's comment. I think
your bottom line above says it all! Is this the sort of quality we can
expect from one of the most prestigious scientific journals these days?

I'd noticed the pet mentioned, but it seemed to be a minor part of
things as the article appeared to be about CO2 capture more than
anything else. Oddly, they refer in the abstract to depolymerised pet's
use in a "counter-reaction", but they haven't previously referred to the specific "reaction" which it is countering! BICBW and just missed it.
One interesting thing is the method of turning waste PET into a suitable reducing agent (at the end of the section "Moist-bed gas-phase CO2 photoreduction procedure in flow"). They shred it, mix it with methanol
and THF, add KOH, and stir for 24 hours at 60°C. Or it's dissolved in
ethylene glycol (a by-product of the previous reaction) and reacted with
KOH at 150°C for 4 hours.

According to that section the efficiency is 60%, and the methanol and
THF are recovered by vacuum distillation, as is the ethylene glycol. But
that's still a lot of energy required. And I wonder what the efficiency
would be on an industrial scale. It's amazing how things don't scale up
or down the way they do in the lab!

--
Jeff

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Jeff Layman wrote:

Fig.1d has a reaction at the top:
CO2 + 2H+  -->  CO + H2 (H2O)
What does the 2H+ signify on the LHS of the equation? What does the H2O
in brackets mean?

H+ is a hydrogen ion, an atom that's lost an electron.

That chemical equation doesn't seem balanced

CO2 + 2H+ ==> CO + H2 (H2O)

1C 2O 2H+ ==> 1C 1O 2H 2H 1O

1C 2O 2H+ ==> 1C 2O 4H

Two hydrogens and two electrons have come from "somewhere", possibly UV
from the sunlight is knocking electrons off the titanium dioxide, but
it's still unbalanced.

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On 28/02/2025 17:25, Tim+ wrote:

Jeff Layman <Jeff@invalid.invalid> wrote:

According to that section the efficiency is 60%, and the methanol and
THF are recovered by vacuum distillation, as is the ethylene glycol. But
that's still a lot of energy required. And I wonder what the efficiency
would be on an industrial scale. It's amazing how things don't scale up
or down the way they do in the lab!

Is this the new “cold fusion”, its main function being to separate gullible
investors from their money?

Tim

All 'green initiatives' are that...
Many years ago I attended a conference hosted by some financial people
to make investors aware of the opportunities.
We had hydrogen, renewable energy, battery technology, carbon capture,
biofuels - the lot.

I asked a few questions but wasn't overly impressed. I was there as a
technical representative of some financial people.

Juts as I was getting to guzzle the sandwiches, I was approached by two
German bankers.
"You seem to understand this: I haf one question. Is any of this
profitable without the government money ja?"
I thought about each presentation.
"No. It isn't"
"Ach then to London we go back. Ve haf been here before, the government
gives, so ve give, then ve make profit and the government stops giving,
and we lose money."

To be honest that is the best description of EcoBollox and GreenCrap I
ever heard.

--
“Those who can make you believe absurdities, can make you commit atrocities.”

― Voltaire, Questions sur les Miracles à M. Claparede, Professeur de Théologie à Genève, par un Proposant: Ou Extrait de Diverses Lettres de
M. de Voltaire

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