Production of renewable petroleum refinery diesel and jet fuel feedstocks from hemicellulose sugar streams

Abstract

We demonstrate how hemicellulose-derived C₅ sugars can be converted into a high-quality petroleum refinery feedstock by a four-step catalytic process. The substitute petroleum consists of normal, branched and cyclic alkanes up to 31 carbons in length and is similar in composition to feedstocks produced in a petroleum refinery today from crude oil. This process can be tuned to adjust the size of the liquid alkanes. In the first step furfural is produced from the acid-catalyzed dehydration of hemicellulose-derived sugar streams in a biphasic reactor. The second step is the aldol condensation of furfural with acetone in a THF solvent and using a NaOH catalyst to produce highly conjugated C₁₃ compounds along with some oligomeric adducts formed through Michael addition reactions. These compounds are then hydrogenated with a Ru/Al₂O₃ catalyst forming both the fully hydrogenated form of the C₁₃ oligomers and also forming larger oligomers by Diels–Alder reactions. The extent of Diels–Alder reactions can be tuned by changing the temperature and feed concentration, thereby adjusting the distribution of liquid alkanes that can be produced. The final step in this process is hydrodeoxygenation using a Pt/SiO₂–Al₂O₃ bifunctional catalyst to produce the liquid alkanes. A simple biorefinery model has shown that about 55% of a furfural–acetone mixture (10 : 3 wt ratio) can be converted into cycle oils while also producing other refinery products such as gasoline and natural gas.