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frequently asked questions



Below are questions that have been asked by industry, experts, advocates and academia. SWAPSOL has done its best to answer them as openly as possible.

The SWAP: 2H2S + CO2 + CH4 => CH4 + 2H2O + sulfur + Carsuls


Q: How does the SWAP eliminate CO2 emissions as claimed?

A: SWAP reacts CO2 in the presence of H2S, forming water, sulfur and carbon-sulfur polymers (Carsuls). The Carsuls are heated and release sulfur, which may be cycled back into the reaction to convert more CO2. If widely adopted, the SWAP can significantly reduce human impact on global warming.


Q: H2S is found in landfills, tanneries, coke ovens, in an estimated one-third of the world’s natural gas reserves, along with a multitude of other locations. How is the SWAP different from the vast number of other H2S removal/recovery technologies?

A: The SWAP is the only H2S elimination technology that also converts CO2.


Q: Isn’t this just another industrial application with a “carbon footprint”?

A: The intrinsic simplicity of the SWAP reactor operation will most likely have a negative carbon footprint because CO2 is consumed during the operation, and the energy liberated during the reaction maintains the process. The catalyst is an inexpensive, non-hazardous natural material.


Q: There appears to be other applications with the reaction. What are they?

A: In other instances, Carsuls can be used to create byproducts, such as carbon fiber-like substances. Elemental sulfur can be utilized for pesticides, sulfuric acid and other traditional uses. At the end of the day, the operator determines the use of the SWAP.


Q: There seems to be a growing interest in biodiesel and algae production as a means to produce hydrogen. Does the SWAP have applications here?

A: Hydrogen production is a growing industry involving a number of promising technologies, many of which have been found to be inefficient and unsustainable. The SWAP-driven sulfur cycle allows for related reactions that can produce hydrogen from H2S. For refiners and other hydrocarbon producers, it may be a cost-effective solution to recover hydrogen while it may find other applications for fuel cells.


Q: It is inevitable that federal legislation in some form will soon mandate strong limits on CO2 emissions from petroleum processors and sharply increase fines for emitters. What is SWAPSOL telling industry?

A: The SWAP can reduce human impact on global warming by converting two “bad actors” (CO2 and H2S) into harmless compounds by reusing hydrocarbon waste to convert CO2 in a self-sustaining process. Users of the SWAP could generate carbon credits while avoiding capital spend on so-called Carbon Capture and Storage (CCS).


Q: Why should industry switch to the SWAP? What are the incentives?

A: No other sulfur removal process converts CO2. In the U.S., legislation to mandate CO2 emissions limits and tax industry is inevitable. In Europe, “cap and trade” schemes have long been in place. The SWAP is a cost-effective technology which serves a clear alternative to Carbon Capture and Storage (CCS). The SWAP would enable users to earn carbon credits while strengthening their bottom line.


Q: Currently, there is a large untapped volume of natural gas in the Middle East that is not marketable due to H2S content where the SWAP could be valuable. The other feedstock in this region is high-sulfur crude oil. Can the SWAP be applied here?

A: Yes. Hydrogenation of high-sulfur crude produces H2S, which then requires disposal. Moreover, the SWAP makes the H2S valuable in that it could allow the user to earn carbon credits when using the SWAP reaction.


Q: What if the CO2 content is high? Will a source of H2S be required?
A: No. The SWAP converts CO2 in proportion to H2S present in the stream. Excess CO2 remains unreacted and is handled through traditional means. However, the SWAP sulfur cycle enables the user to regenerate H2S during the process by cycling carbon-sulfur compounds back into the reaction, thereby sustaining the CO2 conversion reaction.


Q: The reaction as shown is stoichiometric and requires two moles of H2S for reaction with one mole of CO2. It is unlikely that the feedstock will have the precise content of the reactants to complete the reaction properly. What happens if the CO2 content is too low?

A: CO2 is regularly transported by a variety of means. As part of regular operations, CO2 levels would be monitored. In the rare instance that CO2 levels would drop too low, the catalyst may lose activity.


Q: What is the nature of these Carsuls and/or particulates? Are they hazardous?

A: The particulates are carbon-sulfur polymers and are non-hazardous. They would be landfilled or used as raw material for other products.


Q: One would assume that if air, or more precisely, oxygen gets into the reaction, it will shift, leaving the CO2 unreacted and converting the H2S into H2O and SO2. Does the reaction need to be run in an oxygen-free environment?

A: It is preferred, but not necessary. Oxygen would simply waste H2S the reaction can use to convert more CO2. In theory, oxygen would react and oxidize the H2S to form H2O and SO2, but this does not happen, because the temperature of the SWAP column is too low to initiate the H2S oxidation reaction.


Q: What is the lifespan of the catalyst?
A: To date, we have yet to exhaust a catalyst since launching verification studies in 2007.


Q: Most traditional sulfur recovery methods are based on amines. It appears that they get rid of the hazardous wastes by re-injecting them into the deep wells from which they draw the sour gas. How would the SWAP be applied in this instance?


A: The SWAP works with gaseous or liquid H2S and CO2, hence we believe the SWAP, combined with a Claus-related process, would eliminate the need for high-pressure injection into the ground and mitigate or eliminate the need to re-inject hazardous wastes.


Q: How would the SWAP compare with membrane technology?

A: Membrane technologies are capital and space-intensive. The SWAP does not require separation before elimination.


Q: There are a few more new technologies, such as a method of injecting ammonia to facilitate removal of H2S from oil shale. Is this a competing technology to the SWAPSOL technology?

A: No, but since ammonia-injection technology produces H2S, the SWAP could conceivably play an end-role in such operations to eliminate the compound.


Q: There is a bio-digestion process, which uses enzymes to breakdown the H2S. What is your reaction to this technology?

A: This is an emerging technology that is space-intensive and may not be feasible or adaptable for some industrial sites.


Q: There is a new method using transition metals in the reaction. Transition metals are traditionally expensive and ostensibly output a variety of waste products. How would you compare the SWAP?

A: They, too, are catalytic oxidation processes using oxygen and require excessive amounts of energy with considerable waste output. But the SWAP operates at a low temperature and yields no hazardous waste products.


Q: Is a CO2 supply needed? How will CO2 be supplied? Will the plant require a CO2 generation plant on site?

A: Many gas wells have more than enough CO2 already. In other cases where there is a deficiency, CO2 can be transported in. CO2 is regularly shipped both domestically and internationally.


Q: Are the carbon and sulfur products of sufficient quality to be marketed, or is additional treatment needed?

A: They are easily separated and appear to be quite pure compared to other sulfur disposal methods.



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