The raw material used were corn cobs, providing glucose which was chemically dehydrated to furfural. In a 5 step chemical procedure, furfural was converted to terephtalic acid, and mass spectrometry showed that the carbon was 100 % derived from biomass.
China Bio news release, Feb. 25, 2015; Yuya TACHIBANA et al., Nature Scientific Reports doi:10.1038/srep08249
Group at Gunma University develops sustainable route to terephtalic acid