Improved bio-oil upgrading due to optimized reactor temperature profile

Production of second-generation biofuels by upgrading of pyrolysis bio-oil from biomass attracted much attention in recent years. Here, we present a study dedicated to the stabilization of pyrolysis bio-oil over NiMo/Al2O3 catalyst in single-stage fixed bed reactor with different temperature profiles (ramp to the 340 degrees C). Detailed characterisation of the textural properties of the fresh and the spent catalyst and the determination of the changes in physicochemical properties and chemical composition of the liquid and gaseous products have allowed us to discuss the influence of the temperature profile on the catalyst stability during 80 h time on stream of the bio-oil hydrotreatment. We have observed that the lower average temperature in the reactor can yield stabilized bio-oil with physicochemical properties comparable with bio-oil that was hydrogenated at higher temperatures. Moreover, the catalyst long-term stability was higher when using a slower temperature ramp. Thus, the physicochemical properties of the stabilized bio-oil obtained with the lower average temperature in the reactor was maintained uniform with the increasing time on stream, while deterioration of the properties of the hydrotreated liquid products produced under the faster temperature ramp occurred. Additionally, we have shown that no sulfur loss occurred from the NiMo/Al2O3 catalyst during bio-oil hydrotreatment.

Automated summary

The study explores the stabilization of pyrolysis bio-oil using NiMo/Al2O3 catalyst in a fixed bed reactor, showing that lower average temperature in the reactor can yield stabilized bio-oil with comparable physicochemical properties to bio-oil hydrogenated at higher temperatures. Furthermore, the catalyst's long-term stability is higher when using a slower temperature ramp. This research also demonstrates that there is no sulfur loss from the NiMo/Al2O3 catalyst during bio-oil hydrotreatment.