OMC Thermochemistry ($250K to convert water and/or CO2 to hydrogen or syngas)

OMC Thermochemistry, an American cleantech company founded in 2021, has developed an innovative thermochemical process for producing green hydrogen and syngas. Their technology utilizes a scalable fluidized bed reactor, employing heat and readily available, cost-effective materials to split water (H₂O) into hydrogen or simultaneously process H₂O and CO₂ to generate syngas. This approach offers a promising solution for sustainable fuel production in the growing clean energy sector.

(This article contains 3 diagrams and 1592 words.)

Challenges: hydrogen and sustainable fuels

Hydrogen (H₂) serves as a critical chemical feedstock for producing green molecules such as ammonia (NH₃), methanol (CH₃OH), and synthetic hydrocarbons (CH₄, CₘHₙ). The steam methane reforming (SMR) process is responsible for generating the majority of the world's hydrogen, which exceeds 60 million tons annually. This energy-intensive process contributes approximately 2% to global carbon dioxide (CO₂) emissions. For every ton of hydrogen produced through SMR, between 5 and 9 tons of CO₂ are emitted, highlighting the significant environmental impact of this widely used production method.

Clean hydrogen production technologies are experiencing rapid advancements across various methods. These include water electrolysis, which uses electricity to split water molecules; methane pyrolysis, which decomposes methane into hydrogen and solid carbon; biomass gasification, which converts organic matter into hydrogen-rich gas; and geologic hydrogen extraction, which taps into naturally occurring hydrogen reserves. These diverse approaches represent the ongoing efforts to develop more sustainable and efficient hydrogen production methods.

On the other hand, syngas, a mixture of H₂ and carbon monoxide (CO), serves as a key intermediate for producing kerosene through the Fischer-Tropsch synthesis process. Kerosene is commonly used as jet fuel for long-haul flights, but its combustion releases CO₂. A promising approach to carbon-neutral aviation involves using thermochemical processes to react captured CO₂ with H₂O, producing syngas. This syngas can then be converted into kerosene jet fuel, creating a circular carbon cycle and potentially enabling carbon-neutral air travel.

OMC Thermochemistry Technology

The thermochemical conversion of H₂O and CO₂ into syngas has been a subject of research for several decades. This process involves a two-step thermochemical dissociation of H₂O and CO₂.

The first step of this process focuses on the liberation of oxygen (O₂) from the crystal lattice of a metal oxide (MOₓ) catalyst. One commonly used catalyst for this purpose is ceria (CeO₂), which undergoes partial reduction during this initial step.

• Reduction step:

1/k MOₓ → 1/k MOₓ₋ₖ + 1/2 O₂

The reduction reaction in the first step of the thermochemical process is endothermic and requires extremely high temperatures, typically ranging from 1200 ºC to 1600 ºC. This intense heat can be supplied exclusively through concentrating solar energy or electrical resistance heating. To facilitate the removal of produced oxygen (O₂), this step is conducted under low pressure conditions, often near vacuum. These specific conditions are crucial for the efficient liberation of oxygen from the metal oxide catalyst.

In the second step of the thermochemical process, steam (H₂O) and CO₂ are introduced to react with the oxygen-deficient metal oxide (MOₓ₋ₖ). This reaction produces the desired syngas while simultaneously regenerating the original metal oxide (MOₓ). If only steam is used in this step, the resulting product is H₂. This phase of the process effectively completes the cycle, restoring the catalyst to its initial state and yielding the target gas mixture.

• Oxidation step:

1/k MOₓ₋ₖ + H₂O → 1/k MOₓ + H₂

1/k MOₓ₋ₖ + CO₂ →  MOₓ + CO

The oxidation reactions in the second step are exothermic and typically occur at elevated pressures of several bars and lower temperatures ranging from 800 ºC to 1000 ºC. This results in a temperature swing of 200-800 ºC between the two steps of the process.

The extent of reaction (k) is influenced by both the operating temperature and oxygen partial pressure. To optimize material performance, the redox cycle can be controlled through either a temperature-swing approach, a partial pressure-swing method, or a combination of both techniques.

The substantial temperature difference between the two steps in the thermochemical process serves as a key driving force, potentially enabling higher theoretical efficiencies. However, the temperature-swing mode faces practical challenges, including significant heat losses and thermal stresses from cycling between redox regimes.

In contrast, pressure-swing operation varies pressure instead of temperature between steps, allowing for near-isothermal operation and eliminating temperature swings. While this approach reduces thermal stress, it generally yields lower theoretical oxidant conversion efficiency compared to temperature-swing operations.

Consequently, prototype and pilot-scale operations often employ a combination of both modes to optimize solar-to-fuel energy efficiency and oxidant conversion.

The commercialization of thermochemical H₂O and CO₂ conversion has been hindered by several factors, with low thermal efficiency being a primary concern. Most current approaches using active materials like ceria require large temperature swings (> 500 ºC) between reduction and oxidation steps, leading to significant heat losses.

Additionally, this technology has been predominantly linked to concentrating solar power, limiting operational sites and resulting in low-capacity factors and high capital costs. For instance, Synhelion, a Swiss cleantech company founded in 2016, has developed a solar receiver-reactor using concentrated solar energy in a tower configuration with reticulated porous ceria to convert CO₂ and water into syngas. However, this system achieves only about 4% solar-to-syngas conversion efficiency at an average solar input of 42 kW.

OMC Thermochemistry has developed a novel thermochemical technology utilizing electrical resistance heating and cost-effective, abundant iron aluminate (Fe33Al67) in a scalable fluidized bed reactor. This system converts H₂O and/or CO₂ into clean H₂ or syngas with high yields. The new iron aluminate material enables the reactor to operate solely in pressure-swing mode during reduction and oxidation steps, eliminating the need for large temperature swings (> 500 ºC) typical of ceria-based systems, thus significantly reducing heat loss.

Furthermore, the oxidation step can operate at high pressures up to 35 bar with excellent conversion efficiency, allowing for high-pressure syngas or hydrogen output and minimizing energy losses associated with downstream compression.

How OMC Thermochemistry turns water and/or CO₂ to H₂ or syngas

The diagram provided illustrates OMC Thermochemistry's fluidized bed reactor system, which is designed to convert H₂O and/or CO₂ into clean H₂ or syngas.