Hydrodeoxygenation of triglycerides over reduced mesostructured Ni/γ-alumina catalysts prepared via one-pot sol-gel route for green diesel production

Abstract

Environmentally friendly non-sulfided mesostructured Ni/γ-alumina catalysts were synthesized and developed to produce green diesel from canola oil. The catalysts were prepared either by a one-pot sol-gel (SG) via evaporation-induced self-assembly (EISA) or by incipient wetness impregnation (IMP). They were characterized by N2 adsorption-desorption, XRD, XPS, NH3-TPD and TEM. Due to the incorporation of nickel in the mesostructured framework, bulk nickel oxide species are lower for SG catalysts compared to IMP ones. Formation of active metallic nickel was confirmed after in-situ pre-reduction in H2 for both SG and IMP catalysts. Continuous hydrotreatment of canola oil was performed in a down-flow fixed-bed reactor, and the liquid hydrocarbon products mainly contained C15-C18 n-alkanes. SG catalyst exhibited a better stability up to 10 h of time on stream (TOS). The IMP catalyst initially showed higher conversion than SG up to TOS:300 min; it thereafter decreased sharply to values lower than those of SG.