Zeitschrift für Chemieingenieurwesen und Prozesstechnologie
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Methane as emerging raw material for biopolymers

Maximilian Lackner

Biobased polymers can offer the advantages of a reduced carbon footprint, and they are able to reduce microplastics pollution by being biodegradable. Common feedstocks are starch and sugar, which creates a debate around food competition. Methane is an attractive raw material for polymers. It can be sourced from natural gas and non-conventional methane sources, and it is accessible from landfill gas or biogas. Thermocatalytic processes for obtaining polyolefins polyethylene (PE) and polypropylene (PP) from methane already exist at large scale. In this presentation, an alternative, promising approach to make biodegradable polymers from methane is presented: Methanotrophic bacteria consume CH4 to produce polyhydroxyalkanoates (PHA), a class of naturally occurring biopolymers which is degradable also in the marine environment. Methanotrophs like methylosinus trichosporium, methylocystis hirsuta or methylocystis capsulatus are able to yield polyhydroxybutyrate (PHB), a potential replacement for PP. Co-feeding other monomers allows the production of copolymers such as the softer PHBV, which is also of commercial interest. Using methane as feedstock for PHA biopolymer production has the potential to make PHA even more sustainable and cost-competitive, due to higher production rates than PHA-producing cyanobacteria. Other building blocks of interest like isoprene and butanediol are accessible through engineered methanotrophs such as methylomicrobium alcaliphilum. It is expected that methane is the next-generation feedstock, contributing significantly to the biobased, circular economy.