Jet Fuel Range Hydrocarbon Production from Propanal: Mechanistic Insights into Active Site Requirement of a Dual-Bed Catalyst

Abstract

Utilization of sustainable biomass to produce jet fuel range hydrocarbons is imperatively needed to mitigate CO2 emissions and to liberate the over-reliance on fossil resources. Using propanal as the feedstock, an excellent jet fuel range hydrocarbon yield (81.7%), high conversion (ca. 100%), and purity (85%) were achieved over a novel dual-bed Cu/SiO2–TiO2||Ni/ZSM-5 catalyst at low temperature and pressure in only one reactor. The intrinsic active site requirement was further investigated by multitechniques including density functional theory calculation, quantitative CO2/NH3-temperature-programmed desorption/diffuse reflectance infrared Fourier-transform spectroscopy, high-resolution transmission electron microscopy, and thermogravimetric analysis–mass spectrometry. Results showed that for the upstream bed catalyst (Cu/SiO2–TiO2), the Ti–O site pair and Ti Lewis acid site were crucial for enolate formation, carbon-chain growth, and ring closure reactions, which can be altered by the calcination temperature. The synergy between the site strength and number led to a volcanic relationship between acidity/basicity and the intermediate yield. In addition, the downstream bed Ni/HZSM-5 catalyst promoted the hydrodeoxygenation reaction toward hydrocarbon formation.

Tandem Hydrodeoxygenation Catalyst System for Hydrocarbons Production from Simulated Bio-oil: Effect of C–C Coupling Catalysts

“…TiO 2 has a low hydrogenation function and thus a higher chain growth probability. However, Au/TiO 2 showed the highest chain growth probability, in which a mild hydrogenation function of Au enhanced aldol condensation reaction occurs. , …”

“…Acetone is the product of the hydrogenation of acetol and dehydration, and it is also the product of ketonization of acetic acid. Meanwhile, acetone is also a key intermediate for the C–C coupling reaction via aldol condensation on the TiO 2 -based catalysts …”

“…The X-ray composition analysis was performed with a JEOL Centurio EDS X-ray spectrometer. The characterization of the HDO catalyst and C–C coupling catalyst can be seen elsewhere. , Detailed characterization of the synthesized catalyst is reported in section S1. Figures S2, S3, S4, and S5 show the BET isotherms Al 2 O 3 spherical support, linear scan of Ru-MoFeP/Al 2 O 3 and Au/TiO 2 , SEM-EDX mapping of Ru-MoFeP/Al 2 O 3 , and SEM-EDX mapping of Au/TiO 2 , respectively.…”

“…The characterization of the HDO catalyst and C−C coupling catalyst can be seen elsewhere. 62,63 Detailed characterization of the synthesized catalyst is reported in section S1. 2.5.…”

“…Meanwhile, acetone is also a key intermediate for the C−C coupling reaction via aldol condensation on the TiO 2 -based catalysts. 63 Phenol is the main oxygen-containing compound that remained from the reactant mixture. The phenol conversion was therefore used to compare the catalysts.…”