Terephthalic acid from waste PET: An efficient and reusable catalyst for xylose conversion into furfural

This study presents a new approach to produce furfural from xylose using terephthalic acid (TPA) as dual acid catalyst in a water-toluene biphasic system. The process utilizes dual properties of terephthalic acid; its acidity and extremely different solubility at ambient and operating conditions. Terephthalic acid at reaction temperatures acts as homogeneous acid catalyst and at ambient temperature precipitates from the reaction medium almost quantitatively. In addition, TPA for this reaction can be produced from cheap and abundant waste PET. Using 8.9 wt% solution of xylose, the xylose conversion and furfural yield of 91.8% and 70.9%, respectively, was obtained at 190 degrees C for 3 h. The recycling of both, aqueous solution from previous run and TPA originated from waste PET has shown that after 5 runs performed at 190 degrees C for 150 min the yield of furfural reached on average 73.1 mol%. Easy recovery, high thermal stability and reusability of TPA available from waste PET is a great advantage for the use of this acid for the development of an environmentally benign process of furfural production.