Ni phosphide catalysts on Al₂O₃‐zeolite prepared by phosphidation for methyl palmitate hydroconversion

Abstract

BACKGROUNDOne‐stage hydroconversion of fatty‐acid based feedstocks is a promising way to obtain high‐quality fuels. This process is based on hydrodeoxygenation, isomerization and hydrocracking reactions. In this work, Ni2P/Al2O3‐zeolite catalysts were synthesized and tested in hydroconversion of a model compound – methyl palmitate.RESULTSNi2P catalysts were prepared by in situ phosphidation of metallic Ni/Al2O3‐zeolite precursors by PPh3. Mixtures of zeolite (30 wt%) and boehmite were peptized and extruded to obtain the support granules. SAPO‐11, ZSM‐5, ZSM‐22, ZSM‐23 and ZSM‐12 were used as a zeolite component. The catalysts and supports were characterized by a range of physicochemical methods: chemical analysis (ICP‐AES), low‐temperature N2 adsorption, H2‐temperature programmed reduction, NH3‐temperature programmed desorption, Fourier transform infrared spectroscopy of adsorbed CO, X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, and 27Al and 31P magic angle spinning nuclear magnetic resonance. The catalysts were studied in methyl palmitate hydroconversion (one‐stage hydrodeoxygenation‐isomerization‐hydrocracking) in a continuous‐flow fixed bed reactor at 290–340 °C, 2 MPa, H2/feed = 600 Ncm3/cm3 and LHSV = 5.3 h−1. SAPO‐11 containing sample showed high selectivity to C15 and C16 iso‐alkanes (63%, at 340 °C), and all ZSM‐containing samples showed high selectivity to cracked C5–C9 products (55–100%, at 340 °C) with varying amounts of iso‐alkanes (31–57%, at 340 °C).CONCLUSIONThe results show that by choosing the zeolite component of the catalyst it is possible to finely tune product quality in the range from low‐temperature diesel fuel to jet fuel or gasoline. © 2024 Society of Chemical Industry (SCI).