Phase equilibria of bio-oil compounds

Abstract

Thermodynamic information related to bio-oil is very important for the design and development of biorefining and upgrading processes. In this study, the thermodynamic properties of selected bio-oil compounds and their mixtures were measured and modelled at various temperatures and pressures. These data were acquired using various type of phase equilibrium apparatus, mostly designed and developed in house.

In particular, limiting activity coefficients of bio-oil compounds in water, solubility of CO and H2 in bio-oil compounds, mutual solubility of bio-oil compounds and water and excess properties of aqueous solutions of bio-oil compounds at infinite dilution were measured. Rapid Inert gas stripping equipment was designed by Prof. Dominique Richon. Butanol-water mixture was used as a reference system for equipment validation. The equipment was further used for the determination of limiting activity coefficients of bio-oil compounds in water. Limiting activity coefficients of five bio-oil compounds in water were also measured using classical inert gas stripping technique (glass apparatus) at UCT Prague during a research visit. The solubility of CO in bio-oil compounds at different temperatures and pressures was measured using static-analytic VLE technique employing ROLSI™ samplers while the solubility of hydrogen in bio-oil compounds was measured using a continuous flow apparatus at different temperatures and pressures. The partial molar excess thermodynamic properties at infinite dilution were measured using a tandem calo-densimetry technique employing a calorimeter and a vibrating tube densimeter in tandem arrangement. VLLE measurements of bio-oil compounds and water at different conditions were carried out in a high pressure and high temperature static analytic VLLE apparatus, equipped with novel high temperature Pneumatic capillary sampler, designed and developed by Prof. Dominique Richon and D.Sc. (Tech.) Petri Uusi-Kyyny.

Both classical (cubic EoS and local composition liquid activity coefficient) and modern (PC-SAFT EoS) thermodynamic modelling approaches were used in this work. The solubility of CO in bio-oil compounds was modelled with SRK, PR and PC-SAFT EoS. A comparison of these models was made. Hydrogen solubility in bio-oil compounds was modelled with Peng Robinson EoS. The mutual solubilities of bio-oil compounds and water at high temperatures and pressures were modelled using UNIQUAC and NRTL liquid activity coefficient models. Furthermore, Hayden O' Connell and Tsonopoulos correlations were used for the vapor phase corrections in the determination of limiting activity coefficients.