Hydroconversion of methyl palmitate over Ni-phosphide catalysts on SAPO-11 and ZSM-5 composite supports

Zeolite materials (SAPO-11 or ZSM-5) were used to prepare modified Al2O3 supports by mixing with Al oxide hydroxide, peptization with HNO3 and subsequent extrusion. The obtained Al2O3-SAPO-11 and Al2O3-ZSM-5 (with 30 wt% zeolite content) were impregnated by solutions containing Ni and P precursors: phosphate (A), phosphite (I), and hypophosphite (H). Ni-phosphide catalysts were prepared by temperature-programmed reduction in hydrogen flow and characterized by ICP-AES chemical analysis, low-temperature N2 physisorption, H2-TPR, NH3-TPD, XRD, 27Al MAS NMR, XPS. The catalysts were tested in methyl palmitate (MP) hydroconversion (HC, i.e. hydrodeoxygenation (HDO) + hydroisomerization/hydrocracking). 100% MP conversion was achieved over all catalysts (flow reactor at 340 °C, 2.0 MPa, 5.3 h−1). For Ni2P/Al2O3-SAPO-11 catalysts the overall yield of iso-alkanes (iso-C15 and iso-C16) increased in the following order of precursors: A < I < H. The highest yield of iso-alkanes was 21% over Ni2P/Al2O3-SAPO-11 H catalyst. Ni2P/Al2O3-ZSM-5 samples possessed high cracking activity. Alkanes from MP HDO as well as the solvent (n-dodecane) were almost completely transformed to C6–C9 alkanes at 340 °C. Decreasing temperature (290, 270 °C) did not result in significant yield of iso-alkanes over Ni2P/Al2O3-ZSM-5 catalysts.