Carbon Dioxide Solution

Have you heard of the Stenger Wasas Process (SWAP)?

Apparently, it’s an exothermic reaction (produces heat) that takes place between carbon dioxide and hydrogen sulfide and “eliminates” both. It operates over a secret heterogeneous catalyst that is apparently readily available and inexpensive. Sounds too good to be true: Solve global warming and acid rain in one go!

According to the Wiki entry on the subject:

The SWAP is not a CO2 capture process. It is a CO2 conversion and elimination process. In a near-instantaneous reaction, it breaks down CO2 and H2S, rearranges their components and produces water, carbon and sulfur.

It then goes on to tell us that SWAP “permanently removes carbon from the carbon cycle.”

I was followed last week on Twitter by Swapsol and my curiosity was piqued. Behind the Swapsol twitter account is Evan Howell (Swapsol’s EVP, Marketing & Communications) and his twitter bio says: “Our company has verified a process that reacts CO2 and H2S, converting the compounds into water, carbon and sulfur.”

The Wiki entry references just one “paper” entitled: “The Kinetic and Thermodynamic Behavior of Gaseous H2S and CO2 over a Heterogeneous Catalyst” from 2008, by a Dr Roy Drayton, who is president of Thermal Hazard Solutions (www.thsusa.com) who apparently did independent tests.

Howell just sent me a report apparently from Drayton that doesn’t give an awful lot away, although it mentions efficiencies being significantly higher above 150 Celsius and at raised pressure; it leaves me totally unconvinced of their earth-changing claims though, I’m afraid:

The Stenger-Wasas Process (SWAP) as described, in which the gaseous reaction between hydrogen sulfide and carbon dioxide over treated solid heterogeneous catalyst (i.e C09-0108t) was observed to be thermodynamically and kinetically favorable at or below 25oC to 150oC and above. The reaction process is spontaneous and liberates heat. This conclusion is based upon physical experiment data (adiabatic and isothermal calorimetry), as well as theoretical predictive methods.

I asked Howell a direct question about the nature of the catalyst, known enigmatically as C09-0108, this is what he had to say:

Actually, the catalyst is key and what is confidential. Studies are on-going to improve its efficacy.

Fair enough, no company is going to give away trade secrets on such a potentially important development, they’re not going to profit if they do. But I’m worried that so much is being claimed and so little is being said about this. The patent application is for the “process” rather than the key catalyst and only describes the process. The extended abstract doesn’t even mention a catalyst.

This technology could change the world if it’s viable. Morally, shouldn’t it be in the public domain so that it can be validated and applied in industry to clean up the planet?

“Independent verification is important,” Howell told me, “Chemical kinetics and gas chromatography are coming. We’re going slow right now.”

There is one more issue, the process apparently produces carbon and the Wiki entry claims this permanently removes it from the global carbon cycle. Well, that’s not strictly true, unless the carbon byproduct is buried deep underground in an oxygen-free environment it will ultimately revert to its low-energy chemical form – carbon dioxide and re-enter the cycle at some point. Of course, it could be used as fuel or feedstock, which is what I think the company intends, so ultimately it will revert to carbon dioxide sooner rather than later.

Apparently, it was in a New Jersey garage, that “entrepreneur chemist” Jim Wasas and “environmental engineer” Ray Stenger discovered how to convert and eliminate CO2, opening the door to a new energy economy. After pressing Howell a little he eventually told me that the process is more important in terms of oil and gas refining, regarding H2S disposal rather than for its potential in CO2 elimination and solving global warming.

The Swapsol website says: “It’s time to rewrite the chemistry textbooks.” But, I’m afraid that kind of phrase always sets alarm bells ringing and reminds me of the dozens of emails I’ve received over the years making similar claims about the physics textbooks. The energetics don’t quite add up, but at the time of writing Swapsol is offering very little additional information and is holding off engaging with the media until the autumn. That’s an odd stance too, given that I am in the media and it’s only Spring. Moreover, if they’re holding off engaging with the media what are they doing following science journalists on twitter?

Maybe I am missing something. Is the Stenger Wasas Process (SWAP) a genuine solution to our problems waiting to be unleashed? It’s a very happy coincidence that the names of the two inventors mesh nicely together to form a neat acronym, isn’t it? It’s not that I’m doubting their integrity, I’d just like to see some more chemistry. Let’s hope this is not simply another slow burn to dying embers like Steorn was slow, or cold fusion was, or Perepetia was…

It seems that humans are pre-programmed either to predict the end of the world and to monger doom or to tout global panaceas for energy, climate, and all the world’s ills. It’s almost like a collective bipolar syndrome fed by the fragility of the human condition. Personally, I do not believe the end of the world is nigh, but neither do I believe that are any wonder solutions to the serious problems we currently face.

UPDATE: June 2, 2009

I asked a chemist colleague to take a look at the claims, this is what he had to say:

“Concerning this SWAP process, the essence of their claim is:

(1) “Our company, Swapsol, has verified a process that reacts CO2 and H2S, converting the compounds into water, carbon and sulfur.”

(2) The process is exothermic.

The first statement is obviously inaccurate, since the stoichiometry doesn’t work. You have to add a half-molecule of oxygen to the output to make it balance:
H2S + CO2 -> H2O + C + S + 1/2O2

Although, they seem to have used a different approach to balancing their stoichiometry. I’ve dropped irrelevant CH4 terms from both sides, this is how it comes out:

2H2S + CO2 -> 2H2O + 2S + C

Concerning the second statement, this must be true or false regardless of whether the catalyst is known. A catalyst only affects the activation energy needed to drive a reaction. It can’t affect the chemical potential energies of the inputs or outputs. The trouble is that we don’t know exactly what forms the output C and S take, so we can’t do an exact energy budget to verify “exothermicity”. There is talk of the C coming out as nanotubes, for example. However, if the process really is exothermic and has a low activation energy, that would be crucially important to its economics. An endothermic process is expensive.

That said, we can do an energy budget of sorts. If you assume the C and S are not bonded at all, then in that state their energy is higher than if bonded. Once they bond, more energy is released. Therefore, if the process is exothermic even if the C and S on the output are unbonded, then it is exothermic no matter what form the C and S take.

It may be possible to find the bond energies in a reference like the CRC Handbook of Chemistry and Physics and work out a crude energy budget. I’ll try to get around to doing that sometime. The results probably won’t be conclusive.

My trusty old CRC gives the following bond energies in these molecules (in units of kcal/mol):

H-S in H2S = 90
C-O in CO2 = 127
H-O in H2O = 119
C-C in C crystals (probably meaning graphite) = 171
S-S in S crystals = 66

If we take the above chemical equation at face value, then on the left we have:
4 (H-S) bonds + 2 (C-O) bonds = 614 kcal/mol

while on the right we have

4 (H-O) bonds = 476 kcal/mol

Thus if the C and S end up as free atoms, the reaction is endothermic.

If we manage to bond the C and S into typical crystal structures, then on the right we need to add:

1/2 of a (C-C) bond + 1 (S-S) bond = 151.5 kcal/mol

for a grand total of 476 + 151.5 = 627.5 kcal/mol

In this case, the reaction is indeed marginally exothermic.

However, we don’t know a lot of things, such as, what is the actual output state of the C and S. We also don’t know the pressures and temperatures required to drive the reaction in the presence of the mystery catalyst. That is important. For example, taking free C atoms and turning them into diamond is hugely exothermic, but requires absurdly difficult-to-achieve conditions.”

My chemist friend’s hunch is that the claims probably aren’t true, but since we have been given so little information it is difficult to make a definitive assessment one way or the other.