Bimetallic Hierarchical Nanostructured Alumina Material Catalyzes Decarboxylation of Oleic Acid to Produce Long-Chain Alkanes for Bioaviation Kerosene

Abstract

Standard alumina has only a small number of mesopores, which is not conducive to the mass transfer of biomacromolecules and so affects the catalytic activity in the case that this material is used as a catalyst substrate. In the present work, hierarchical nanostructured γ-Al2O3 (HNCγ-Al2O3) assembled from nanosheets was obtained after high-temperature calcination and a low-temperature hydrothermal treatment of an Al-MOF precursor. This material had a high Brunauer–Emmett–Teller (BET) surface area (266.8 cm3/g) and pore volume (0.64 cm3/g) together with abundant mesopores. Both monometallic and bimetallic Pt/Ni catalysts were prepared using HNCγ-Al2O3 as a carrier and applied to the decarboxylation of oleic acid to produce C8–C17 alkanes. Compared with monometallic materials, the introduction of a second metal increased the quantity and strength of acidic sites on the catalyst. A synergistic effect obtained by incorporating Pt and Ni in the bimetallic catalysts increased the number of oxygen vacancies in the materials and lowered the temperature required to reduce NiOx. At 340 °C, Pt–Ni/Al-1:3 catalyzed the decarboxylation reaction of oleic acid, giving a yield of the product C8–C17 alkanes of 85.3% after a 4 h reaction