Scientists from Lawrence Livermore National Laboratory have combined biology with 3D printing in order to build the very first reactor that is able to produce methanol from methane continuously at room temperature, under pressure. The team removed enzymes from methanotroph (a type of bacteria that eats methane) and mixed them with polymers that they had printed (or molded) into innovative reactors.
Sarah Baker, lead of the project says the remarkable thing is that the enzymes actually retain as much as 100 percent activity inside of the polymer. The printed enzyme-embedded polymer is extremely flexible, giving it a lot of room for future development and will be useful in a large range of applications, especially those that involve gas and liquid reactions.
Thanks to advances in both the extraction techniques of oil and gas, there are now vast amounts of natural gas that are composed of by primarily methane readily available. Unfortunately, large amounts of this methane is leaked during ventilation or flared during these operations. This is due to the fact that this gas is difficult to store and transport in comparison to other more valuable liquid fuels. Methane emissions contribute currently to about one third of the current net global warming problem, mainly from these as well as other distributed sources including agriculture and even landfills.
Present industrial technologies that convert methane to far more valuable products such as steam reformation must operate at extremely high temperatures and large pressures. This requires a large number of unit operations and yields a range of products. Because of this, the current industrial technology standards have a very low efficiency when it comes to methane conversion to final products and is only able to operate economically on extremely large scales.
A technology that holds the ability to efficiently convert methane into other hydrocarbons is required in order to create a profitable way to convert sources of methane and natural gas to liquids for further processing. Thus far, the only known catalyst both industrial and biological to convert methane to methanol under ambient conditions with high efficiency is the enzyme methane monooxygenase (MMO), which is able to convert methane to methanol. The reaction can be carried out by methanotrophs that contain the enzyme, but this approach requires a lot of energy in order to be maintained and to continue providing metabolism of the organisms. The team instead separated the enzymes from the organism and used the enzymes directly.
The team discovered that isolated enzymes offer the promise of highly controlled reactions at ambient conditions with higher conversion efficiency and far better flexibility. Joshuah Stolaroff, an environmental scientist on the team says that up until recently, most industrial bioreactors are stirred tanks, which are inefficient for reactions that occur among gas and liquid reactions. He continues that the concept of printing enzymes into a robust polymer structure opens the door for new kinds of reactors with much larger throughput and lower energy consumption.
The team quickly realized that the 3D printed polymer has the potential to be used and reused over a number of cycles and used in higher concentrations than possible with the conventional approach of the enzyme dispersed in solution.
The research was published in full in Nature Communications journal and holds the potential to lead to more efficient conversions of methane to energy production.