Bio-based ethylene glycol (EG) has typically been produced from bioethanol via petrochemical routes, i.e. by dehydration and epoxidation, followed by hydrolysis (Scheme 4). An alternative, simpler approach to preparing EG via hydrogenolysis of carbohydrates has also been investigated: cellulose is hydrolyzed into glucose, which undergoes pyrolysis to form C2 species, particularly glycolaldehyde. The latter is then hydrogenated to give EG (Scheme 5). Production of high purify EG via this route is challenging due to complex mixtures formed during the cleavage of glucose. Enhancements in EG selectivity have been achieved by using a variety of tungstate catalysts. It is more economically viable to utilize wood or biomass wastes directly, rather than neat cellulose; however, lignocellulose present in these raw materials have been found to impact the activity of catalysts. Pretreatments of biomass feedstocks, leading to improved EG yields, have been reported. xylene production. The critical step in the HMF route is the Diels-Alder cycloaddition between 2,5dimethylfuran and ethylene. Various catalysts including zeolites, carbon, silica, titania and alumina have been studied. Feng et al. used mesoporous tin phosphates with controllable acid sites and improved mass transfer, resulting in the inhibition of 2,5-hexanedione byproduct formation and production of pxylene with 93% yield, and at a high productivity of 173 mol/mol acid sites. Zhao et al. obtained pxylene with 97% yield and quantitative conversion of dimethylfuran, using alumina-doped H-Beta zeolite catalyst. One drawback of the HMF route is the high temperature and high ethylene pressure required for the cycloaddition. Also, the PTA produced is only bio-based if the ethylene used is bio-derived, which further adds to the cost. The isobutanol route was developed by Gevo Inc., where isobutanol is obtained by fermentation of glucose using proprietary bacteria, then dehydrated into isobutylene, which then forms p-xylene at modest conversion but high selectivity (75-85%) via dimerization and subsequently dehydrocyclization.