DOE OSTI2022
Carbon dioxide and methane are the two most abundant greenhouse gases with methane having a higher global warming potential (GWP) than carbon dioxide. Use of methanotrophs as a biocatalyst is a green alternative to chemical conversion of methane. Methanotrophs were immobilized in a 4-arm poly (-ethylene glycol)-tetra-acrylate, PEGTA, hydrogel that is supported by a 3D printed lattice containing micropores. The consumption rate of methane was 2.5 and 42 g CH 4 /L-hr in samples that were at 1 and 3 atm, respectively. A small increase in pressure of the system improves the consumption rate by almost 20x with minimal changes to the reactor system. This system relies on the mass transport of gas through a solid-like material rather than dissolving the gas in a liquid. Immobilization of cells in hydrogel allows for higher cell density and overall increased conversion rates compared to traditional stirred tank reactors. There are many other applications of the use of immobilized biological materials in polymers that require gas-phase reactions.