Jun 17 2016
Scientists from Lawrence Livermore National Laboratory (LLNL) have merged both 3D printing and biology to develop the very first reactor that will have the potential to continuously create methanol from methane at room pressure and temperature.
Lawrence Livermore National Laboratory chemist Sarah Baker holds a gas chromatography vial used to measure the amount of methanol produced by the enzyme-embedded polymer. Photos by George Kitrinos/LLNL
The scientists removed enzymes from methanotrophs, which is a type of bacteria that eats methane. The team then mixed the methanotrophs with polymers which molded or printed into innovative reactors.
The research, which could help the conversion of methane to energy production in a much efficient manner, is featured in the June 15th issue of Nature Communications.
Remarkably, the enzymes retain up to 100 percent activity in the polymer. 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.
Sarah Baker, Chemist, LLNL
Enhancements in the extraction techniques of both gas and oil have made new stores of natural gas available, which primarily contain methane. However, huge volumes of methane is flared, vented, or leaked during these processes, partly due to the fact that it is difficult to store and transport gas, compared to liquid fuels that are more valuable. Methane emissions play a major role, as they contribute approximately one-third of the current net global warming potential, primarily from these and various other distributed sources like landfills and agriculture.
The existing industrial technologies for transforming methane into valuable products, such as steam reformation, work at increased pressure and temperature, yield a variety of products, and need an increasing number of unit operations. Due to this, existing industrial technologies have a low efficiency of methane conversion to final products and are capable of functioning economically only at extremely large scales.
The team reported that a technology to transform methane to other hydrocarbons is required as a profitable way to carry out the conversion of “stranded” sources of methane and natural gas (sources that are temporary, small or not close to pipelines) to liquids for advancing the process.
The enzyme methane monooxygenase (MMO), which transforms methane to methanol, is the only available catalyst (biological or industrial) to transform methane to methanol under ambient conditions along with high efficiency. The reaction can be executed by methanotrophs containing the enzyme. However, this approach needs energy for metabolism and upkeep of the organisms. The team instead split the enzymes from the organism and directly used the enzymes.
The scientists discovered that isolated enzymes guarantee highly controlled reactions at ambient conditions with increased flexibility and higher conversion efficiency.
Up to now, most industrial bioreactors are stirred tanks, which are inefficient for gas-liquid reactions. 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.
Joshuah Stolaroff, Environmental Scientist, LLNL
The team further discovered that the 3D-printed polymer was capable of being reused for an increased number of cycles and also has the potential of being used in higher concentrations unlike the standard approach of the enzyme scattered in solution.
Other Livermore team members include: Jennifer Knipe, Craig Blanchette, Joshua DeOtte, James Oakdale, Amitesh Maiti and Jeremy Lenhardt. The LLNL team collaborated with (link is external) Northwestern University (link is external) researchers Sarah Sirajuddin and Professor Amy Rosenzweig.
The research was funded by the Laboratory Directed Research and Development program.