Scientists propose converting natural gas directly into hydrogen in gas fields

Researchers at Skoltech have found a way to produce hydrogen from natural gas with an efficiency of 45%, directly in the gas field, by injecting steam and a catalyst into a well and adding oxygen to ignite the gas. The catalyst-assisted combustion creates a mixture of carbon monoxide and hydrogen, from which the latter can be easily extracted. This technology will help accelerate the transition from fossil fuels to clean hydrogen energy. The research was published in Fuel.

About 80% of energy comes from fossil fuels, such as oil and natural gas, which when burned releases carbon dioxide, which threatens the environment and contributes to climate change. Although gas, with its many toxins, is considered “cleaner” than oil, it still emits carbon dioxide when burned, making it a threat to the environment.

Hydrogen, which only emits water vapor, could be a healthier alternative. However, the widespread use of this “green” energy source is hampered by production problems.

For the first time, a team from the Skolkovo Institute of Science and Technology in Moscow has proposed extracting hydrogen from the reservoirs of natural gas fields, which are rich in hydrocarbons containing a large amount of hydrogen at the molecular level. This means that once converted, hydrocarbons can provide an abundance of ‘green’ fuel.

The team has proposed an efficient, multi-step process for producing hydrogen from gas fields. First, steam is injected into the well along with a catalyst that will later help separate hydrogen from the natural gas components. Air or pure oxygen is then pumped in to ignite the gas directly in the reservoir.

With the help of the steam and the catalyst, the natural gas burns and is converted into a mixture of carbon monoxide and hydrogen. The carbon dioxide formed from the carbon monoxide remains in the reservoir and does not contribute to the greenhouse effect.

In the final stage, hydrogen is extracted from the well through a membrane that blocks other combustion products, leaving the carbon monoxide and carbon dioxide permanently underground.

The researchers tested their process in laboratory reactors that simulated a real gas reservoir environment. They placed crushed rock in the reactor and then pumped in methane, the main component of natural gas, along with steam and a catalyst, and then oxygen. The pressure in the reactor was maintained at a level typical of gas reservoirs (eighty times higher than atmospheric pressure).

As the experiment progressed, the team analyzed the composition of the gases in the reactor to assess the efficiency of methane conversion to hydrogen. It turned out that most of the hydrogen – 45% of the total gas volume – was formed at 800°C, with large amounts of steam being injected into the reactor.

To make the reaction as efficient as possible, there would need to be four times more steam than natural gas. The researchers chose the temperature of 800°C because it is easy to achieve when burning natural gas and does not need to be maintained artificially.

The hydrogen yield also depended on the composition of the rock. For example, in experiments with porous aluminum oxide, the hydrogen yield was 55%. The higher efficiency in this case is explained by the fact that aluminum oxide is inert, that is, it does not react with the surrounding elements. Natural rock contains other, more active minerals that can react with the components of the gas mixture and affect the hydrogen yield.

“All stages of the process are based on proven technologies that have not previously been adapted for the production of hydrogen from real gas reservoirs. We have shown that our approach can help efficiently convert hydrocarbons into ‘green’ fuels in the field environment. of a maximum of 45%. In the future, we plan to test our method in real gas fields,” said Elena Mukhina, Ph.D., senior research scientist at Skoltech Petroleum and the leader of the project.