Preparation of Ni/biochar Catalyst for Hydrotreating of Bio-Oil from Microalgae Biomass

Abstract

A new catalyst for hydrotreating process mainly including hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) was prepared by introducing Ni onto the surface of biochar obtained from microalgae biomass pyrolysis. The co-product bio-oil obtained from the pyrolysis was treated under H₂ pressure on the as-synthesized Ni/biochar catalyst. The whole process was established in a close loop cycle illustrating its high efficiency in comparison to other HDO or HDN processes. The catalyst was prepared through two-step procedure including biochar production and impregnating of Ni precursor onto the biochar. The pyrolysis of microalgal biomass was established at 400 °C for 2 h producing mainly the biochar and the bio-oil. The biochar was then doped with Ni²⁺ by incipient wetness impregnation followed by drying and calcination at suitable temperature for a certain time. The upgrading process including hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) reactions of bio-oil obtained from microalgal pyrolysis was investigated at various parameters such as temperature, time, catalyst dosage and stirring speed for converting bio-oil obtained from microalgal pyrolysis to rich hydrocarbon product. The Ni/biochar catalyst synthesized from the biochar through impregnation was used in the upgrading process. The results showed that the Ni/biochar catalyst could be very effective in the upgrading process producing mainly n-heptadecane as a very important component of diesel fuel. Some techniques were applied for characterizing the catalyst, feedstock and product such as XRD, H₂-TPR, GC-MS and some standard ASTM methods.

Graphical Abstract