Hydroconversion of Waste Cooking Oil into Green Biofuel over Hierarchical USY-Supported NiMo Catalyst: A Comparative Study of Desilication and Dealumination

Abstract

Abstract:The hydroconversion of waste cooking oil into hydrocarbon fuel was investigated over the hierarchical USY zeolite-supported NiMo catalysts which were prepared by dealumination ((NH 4 ) 2 SiF 6 )/desilication (NaOH). The physical and acidity properties of the hierarchical catalysts were characterized by X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) infrared spectroscopy of adsorbed pyridine (Py-IR), ammonia temperature-programmed desorption (NH 3 -TPD), and H 2 temperature-programmed reduction (H 2 -TPR). The Brønsted/Lewis (B/L) acid distribution was little affected by dealumination and the acid density decreased significantly. However, the highly-desilicated catalysts decreased the B/L ratio obviously. Therefore, many more Mo species in the NiMoO 4 − and MoO 3 phases were produced in the AHFS-treated catalysts, while more high-valence-state Mo species in the NiMoO 4 − phase were formed in the NaOH-treated catalysts.The AHFS-treated catalysts showed higher catalytic activity and better DCO 2 selectivity and selective cracking for jet fuel. The 42.3% selectivity of jet fuel and 13.5% selectivity of jet-range aromatics was achieved over the 8 wt % (NH 4 ) 2 SiF 6 -treated catalyst with 67% DCO 2 selectivity.

Influence of Impurities and Oxidation on Hydroconversion of Waste Cooking Oil into Bio‐jet Fuel

“…Generally, the triglycerides are converted into alkanes through three reaction pathways: HDO, decarbonylation (DCO), and decarboxylation (DCO 2 ). In previous works, the selectivity for DCO x /HDO could be identified by the C 17 /C 18 ratio , , . As illustrated in Fig.…”

“…WCO is two to three times cheaper than vegetable oils and has become a promising feedstock in biofuel production , . However, compared with vegetable oils, WCO contains many different impurities.…”

“…Jet fuel production from WCO has been focused on the deoxidation mechanism, kinetics, and the selectivity of jet fuel , . Some authors researched the deactivation of catalysts using oleic acid as a modeling of WCO , .…”

Hydroconversion of Waste Cooking Oil into Bio-Jet Fuel over NiMo/SBUY-MCM-41

“…Table 2 shows that the strong acidity of SBUY-MCM-41 is much higher than that of Al-MCM-41 owing to the contribution of the microstructure of the pore walls in SBUY-MCM-41. The Brønsted/Lewis (B/L) ratio (2.9) of USY is high, indicating that USY is dominated by Brønsted acidity [15]. Compared with USY, SBUY-MCM-41 displays fewer acid sites, especially Brønsted acid sites, because USY was decomposed into secondary building units.…”

“…Recently, waste cooking oil (WCO) has emerged as a promising feedstock for biofuel production [10][11][12] because it is 2-3 times cheaper than plant oils [13]. The deoxygenation mechanism and the selectivity for the formation of jet fuel have been the focus of WCO research [14,15].…”