Direct and efficient liquefaction of potato peel into bio-oil

The world has become dependent on petroleum as a feedstock for most products that we use in our daily lives. As an alternative, bio-refineries that transform biomass into biofuels and primary chemicals are emerging. Actually, many wastes are not fully recycled. For instance, potato peel is a cheap residue available from the potato industry. Up to now, potato peel has been used mostly for livestock feeding. Here, potato peel waste was subjected to direct acid liquefaction at 160 °C in 2-ethylhexanol and diethylene glycol using p-toluene sulfonic acid as catalyst. The product was characterized by infrared spectroscopy, chemical analysis, hydroxyl number and acid value. Results show that liquefaction was achieved in yields higher than 80%. The reactional profile shows two time zones, one comprising the process of liquefaction and one corresponding to the process of decomposition. Kinetics indicate that the liquefaction process occurs 1.9 times faster than the decomposition process. Overall, our findings show for the first time that, despite the water content, potato peel waste can be used to produce bio-oil. The products can be further used as fuels or refined chemicals such as levulinic acid, furfural, 5-hydroxyfurfural, dimethyl furfural and sugars in fermentation processes.