By combining biology and 3D printing, Lawrence Livermore National Laboratory (LLNL) scientists have created a reactor that continuously produces methanol from methane at room temperature and pressure.

The team removed enzymes from methanotrophs, bacteria that eat methane, and mixed them with polymers that they printed or molded into innovative reactors.

“The printed enzyme-embedded polymer is highly flexible for future development and should be useful in a wide range of applications, especially those involving gas-liquid reactions,” said Sarah Baker, LLNL chemist and project lead.

Advances in oil and gas extraction techniques have made vast new stores of natural gas, composed primarily of methane, available. A large volume of methane, however, is leaked, vented, or flared during these operations, partly because the gas is difficult to store and transport compared to more-valuable liquid fuels. Methane emissions also contribute about one-third of current net global warming potential.

A technology to efficiently convert methane to other hydrocarbons is needed as a profitable way to convert “stranded” sources of methane and natural gas to liquids for further processing, the team reported.

The only known catalyst (industrial or biological) to convert methane to methanol under ambient conditions with high efficiency is the enzyme methane monooxygenase (MMO), which converts methane to methanol. The reaction can be carried out by methanotrophs that contain the enzyme, but the approach inevitably requires energy for upkeep and metabolism of the organisms. Instead, the team separated the enzymes from the organism and used the enzymes directly.

The researchers found that isolated enzymes offer the promise of highly controlled reactions at ambient conditions, with higher conversion efficiency and greater flexibility.

The 3D-printed polymer could be reused over many cycles and used in higher concentrations than possible with the conventional approach of the enzyme dispersed in solution.

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