Catalytic Cracking of Inedible Oils for the Production of Drop-In Biofuels over a SO42–/TiO2-ZrO2 Catalyst

Abstract

Triglycerides from animal fats and vegetable oils are used as the sustainable feedstocks for the generation of biofuels. Tung oil, rubber seed oil, Jatropha curcas oil, waste cooking oil, and waste acidified oil were selected as the triglyceride feedstocks for the production of drop-in biofuels by a catalytic cracking process. The one-step process was carried out in a laboratory-scale fixed-bed reactor using a SO42–/TiO2-ZrO2 catalyst. The catalyst exhibited an excellent performance of cracking, deoxygenation, and aromatization reactions. Moreover, it could be repeatedly used for more than 15 times without an obvious deactivation. The catalytic cracking process resulted in a high yield (65–72%) of the biofuel, which showed a low acid value (3.78 mg KOH/g) and low oxygen content (1.49%). The biofuels were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, proton nuclear magnetic resonance, and gas chromatography–mass spectrometry, suggesting that the dominant components of the biofuels are hydrocarbons in the range of C6–C26, including 17% alkanes, 56% olefins, and 22% monocyclic aromatics. These bio-hydrocarbon fuels in the crude form are chemically identical or near-identical to petroleum-based fuels, which have an attractive fraction distribution (>32% bio-gasoline, >50% green diesel, and <11% heavy fraction) and can be fractionated and used in different formulations depending on the types of desired fuels.