Thiozen, an American cleantech company founded in 2020, develops an innovative process that converts hydrogen sulfide, a common waste stream in the energy sector, into hydrogen gas. This procedure not only generates inexpensive hydrogen but also reduces carbon emissions in comparison to conventional hydrogen sulfide treatment methods.
Challenges: hydrogen fuel
It’s more important than ever to switch to eco-friendly energy sources. The switch to clean electricity sources, like renewables, and electrifying end uses will be two of the most important parts of this transition. However, gaseous fuels may be needed for some end uses, especially in heavy industry and shipping, because they are more reliable and have a higher energy density. Having a carbon-free chemical energy carrier may also help people get energy in the winter.
Hydrogen (H₂) has been widely proposed as a fuel that can meet these needs with minimal greenhouse gas emissions. Industries that are hard to decarbonize, like steel production, long-distance transportation, shipping, and aviation, can use hydrogen to do so. It can also be used as a chemical feedstock and to store renewable electricity during the off-season.
Today, more than 95% of hydrogen is produced using natural gas in steam methane reformers (SMRs). The carbon intensity of hydrogen production using SMRs without carbon capture is 10.4 tons of CO2 emitted for each ton of hydrogen produced.
Green hydrogen can be produced via electrolysis of water, pyrolysis of hydrocarbons, or solar heating using renewable energy sources such as nuclear, solar, and wind. The extraction of geologic hydrogen from the undersurface is also promising to produce low-cost green hydrogen.
We researched many green hydrogen startups to understand how their green hydrogen technologies work. You may become a member and check out our research on green hydrogen startups.
Thiozen Technology
Thiozen develops an innovative technology that turns hydrogen sulfide (H₂S) byproducts into valuable hydrogen gas. Hydrogen sulfide is a significant byproduct in various industries across the United States. It is created in large quantities as a byproduct of fuel desulfurization. It is also co-produced with natural gas. It is a colorless gas known for its pungent “rotten egg” odor at low concentrations, and it is extremely flammable and highly toxic. It needs to be converted into less toxic components.
The current technology for treating hydrogen sulfide is the Claus process, which creates elemental sulfur (S) according to the following overall chemical reaction:
H₂S + ½O₂ → S + H₂O.
Thiozen develops an innovative process that first combines water, hydrogen sulfide, and iodine (I₂) to form hydrogen iodide (HI). Then, gaseous hydrogen iodide is thermally decomposed into hydrogen. This process could produce hydrogen with about 1.2 kg of CO₂ per kg of H₂, which is less than 20% of the CO₂ emissions from conventional steam methane reforming methods.
How Thiozen turns hydrogen sulfide into hydrogen
The diagram below depicts the process of how Thiozen turns H₂S into hydrogen gas and sulfur dioxide (SO₂).
The process typically includes steps of HI formation, SO₂ separation, HI decomposition, and H₂ separation.
- HI formation
First, H₂S is reacted with I₂ and H₂O in the HI formation reactor. The HI formation reactor can be a bubble column, a spray tower, or an agitated tank reactor. This process generates a mixture of dissolved HI and SO₂ according to the following chemical reaction:
H₂S + 3I₂ + 2H₂O → 6HI + SO₂
The reaction is performed at 20–150 ºC and 1–45 bar. The produced hydroiodic acid concentration is 20–56 wt%. A gas effluent stream output from the HI formation reactor that contains impurities is not used by the rest of the process.
- SO₂ separation
The mixture of dissolved HI and SO₂ is then heated in a heater. SO₂ is separated from the heated mixture by using a vapor-liquid separator such as a flash drum at 80–250 ºC and 1–50 bar.
- HI decomposition
The H₂O/HI mixture is vaporized to form gas-phase hydrogen iodide by using a heat exchanger and a furnace. The gaseous HI is decomposed to H₂ and iodine (I₂) in a H₂ formation reactor such as a packed bed reactor, according to the following reaction:
2HI ↔ H₂ + I₂
This reaction is catalyzed by metals, metal sulfides, or carbon materials at 200–700 ºC and 1–50 bar. The HI decomposition reaction converts 10–25% gaseous HI to hydrogen and iodine. The resulting reactor effluent stream then passes through the heat exchanger and is further cooled by a cooler.
- H₂ separation
The produced hydrogen gas is separated from the cooled reactor effluent stream by using a vapor-liquid separator such as a flash drum. The remaining H₂O/I₂/HI mixture is recycled and reused at the HI formation reactor.
How much hydrogen can be produced via Thiozen process
Refineries process a substantial amount of hydrogen sulfide, which could significantly influence the global hydrogen market.
In 2015, the extraction and processing of hydrocarbons through the Claus process resulted in the production of approximately 40.6 million metric tons of sulfur as a byproduct. This process has the potential to generate hydrogen from hydrogen sulfide, equating to an annual production capacity of 7.6 million metric tons of hydrogen. This amount constitutes over 10% of the global annual hydrogen production, estimated at 65 million metric tons for various purposes, translating into a potential value of billions of dollars each year.
Thiozen Patent
- US11104574B2 Hydrogen Sulfide Mediated Water Splitting For Hydrogen Gas An Sulfur Dioxide Production
Thiozen Technology Applications
- Biorefining
In the context of biorefining, Thiozen’s technology can play a crucial role in producing hydrogen, which is essential for various biofuel production processes. Hydrogen is used in hydrotreating and hydrocracking processes to remove impurities and to break down larger molecules into smaller, more valuable ones like biofuels. By providing a low-emission hydrogen source, Thiozen’s process can help biorefineries reduce their carbon footprint and improve the sustainability of biofuel production.
- Natural Gas Processing
For natural gas processing, Thiozen’s technology offers a solution to treat sour gas streams, which contain hydrogen sulfide. Removing hydrogen sulfide is necessary to meet product gas specifications and to prevent corrosion in pipelines and processing equipment. Thiozen’s process not only removes hydrogen sulfide but also converts it into hydrogen gas and elemental sulfur, adding value and reducing emissions associated with traditional sweetening processes. This application is particularly valuable for natural gas processing facilities looking to enhance their environmental performance and operational efficiency.
- Fuel Refining
In fuel refining, hydrogen is a critical input for refining processes, including hydrocracking and desulfurization, which are used to improve the quality of fuels and to meet environmental regulations for sulfur content. Thiozen’s technology can supply low-emission hydrogen to refineries, supporting them in producing cleaner fuels while minimizing their environmental impact. Given the significant role of hydrogen in refining processes, the adoption of Thiozen’s technology can contribute to the decarbonization of the fuel refining sector.
Thiozen Products
Thiozen has validated its technology in an in-field pilot unit in the Permian Basin. The success of these pilot projects is crucial for demonstrating the commercial viability and scalability of Thiozen’s technology. The company aims to use the funds from recent investments and grants to scale its technology to commercial demonstrations.
Thiozen Funding
Thiozen has raised a total of $4.4M in funding over 4 rounds:
- a Non Equity Assistance round
- a Seed round
- two Grant rounds
Their latest funding was raised on Feb 29, 2024 from a Grant round.
Thiozen Investor
Thiozen is funded by 5 investors:
National Science Foundation is the most recent investor.
Thiozen Founder
Ryan Gillis, William H. Green, and Ajay Bawa are Co-Founders.
Thiozen CEO
Ryan Gillis is CEO.