Polymer turns methane into methanol

SCIENTISTS have combined enzymes with 3D-printed polymers to create the first reactor that can continuously produce methanol from methane at room temperature and pressure.

A team from the Lawrence Livermore National Laboratory (LLNL), US removed the enzymes from methanotrophs – methane eating bacteria – and embedded them into polymers that they 3D-printed to create the new reactors.

Industrial technologies that are currently available to convert methane to more valuable products, such as steam reformation, operate at high temperature and pressure and yield a range of products. This results in low efficiency of methane conversion to final products and can only operate economically at very large scales.

The team wanted to create a technology that could efficiently convert methane to other hydrocarbons at room temperature and pressure. They decided to use the methane monooxygenase (MMO) enzyme, as this is the only known catalyst (industrial or biological) which can convert methane to methanol under ambient conditions with high efficiency.

By separating the enzymes that cause the conversion reaction from the organisms that carry them allowed energy savings that would have been required for the upkeep and metabolism of the organisms. The team found the enzymes retained up to 100% activity when they were mixed into the polymer and were highly flexible. This would allow the team to explore new high-throughput reactor designs.

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

'Up to now, most industrial bioreactors are stirred tanks, which are inefficient for gas-liquid reactions,' said Joshuah Stolaroff, an environmental scientist at LLNL. 'The concept of printing enzymes into a robust polymer structure opens the door for new kinds of reactors with much higher throughput and lower energy use.'

The next step for the team will be to use the polymer reactors in various gas-liquid reactions to find a range of applications the technology can be used for.

Nature Communications, DOI: 10.1038/ncomms11900