Effective Cu/Re promoted Ni-supported γ-Al2O3 catalyst for upgrading algae bio-crude oil produced by hydrothermal liquefaction

Catalytic hydrotreating of algae bio-crude oil from hydrothermal liquefaction (HTL) Nannochloropsis sp. was performed. Different Ni-based catalysts, including Ni/γ-Al2O3, Ni-Cu/γ-Al2O3, Ni-Re/γ-Al2O3, and Ni-Cu-Re/γ-Al2O3, (10%Ni, 5%Cu, 2.5%Re) were used in upgrading the oil. Most catalytic systems could effectively eliminate S decrease N O contents, enhance more than 20% improvement higher heating value (HHV) bio-oil (34 to 41–45 MJ/kg). Introducing only Cu CO hydrogenation resulting aromatic alcohol compounds. While addition Re is effective for hydrodeoxygenation, it lowers denitrogenation due amination reaction. Ni-Cu-Re/γ-Al2O3 ternary alloy offered best results on overall performance, achieving highest upgraded yield 58 wt% energy recovery process (ERupgrade) 64.6%. As ER HTL (ERHTL) ca. 71.8%, (ERoverall) biomass 46.4% can be achieved catalyst. Carbon efficiency approx. 47.7% attained as carbon feedstock retained bio-oil. In addition, reaction pathways formation different hydrotreated products catalyzed by mono-, bi-, tri- metallic Ni-Cu-Re have been proposed.