Catalytic Upgrading of Residual Biomass Derived Bio-oil over Molybdenum Carbide

Abstract

The present paper reports a study of molybdenum carbide as heterogeneous catalyst in the hydrodeoxygenation (HDO) reaction of bio-oils from acacia wood or empty fruit bunches of palm oil (EFB) obtained by hydrothermal liquefaction process. Mass molybdenum carbide was prepared using commercial MoO3 as precursor through the carburization methodology. The solid was characterized by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy. For comparison purposes, the HDO reaction was also performed using a NiMo-based commercial catalyst, which was exposed to sulfidation previous to catalytic test. The reactions were performed in a batch-type reactor under reducing atmosphere (H2) at 350 °C and autogenous pressure. The hexagonal β-Mo2C phase obtained during the carburization process was highly active in the deoxygenation reaction, which resulted in enhanced HDO of bio-oils whose heating value is much higher than the heating value of untreated acacia (from 27.6 to 41.1 MJ/kg) and EFB bio-oils (from 29.1 to 36.9 MJ/kg). The higher heating value of the upgraded bio-oil with Mo2C and the ease recovery of the catalyst for recycling are promising advantages for the material to be used in relevant processes as an alternative to sulfided catalysts. On the other hand, the upgraded bio-oils have physicochemical characteristics suitable for their coupling in traditional fossil fuel production processes.