(277a) Biomass Gasification Using Carbon Dioxide: Chemistry and Process Modeling

Gasification is partial oxidation of biomass to produce syngas, which can be used as a feedstock in industrial applications for electricity, chemicals and fuel production. Air, oxygen and steam have been widely used as oxidizing medium in the gasification process. The use of Carbon dioxide (CO₂)as the oxidizing agent in biomass gasification has been explored in limited studies, and it is shown to improve CO production and biomass conversion. The focus of this study is to understand the chemistry or sequence of reactions occurring during the process.

The process of biomass gasification using CO₂ as the oxidizing agent is carried out in a bench scale bubbling fluidized bed reactor at different temperatures (600⁰C - 850⁰C). The syngas composition, tar concentration and biomass conversion are used to determine the dominant set of reactions occurring within the given range of temperature.  A number of gas analysis instruments such as a GC/MS (Agilent 7890/5975), a micro GC (Agilent 490), a portable gas analyzer (Nova 7905AQN4), and an FTIR are used to collect necessary information.

Furthermore, a model for this process is developed using ASPEN plus. The model utilizes Gibbs free energy minimization to predict the effect of operating parameters such as temperature, pressure, and oxidizing media on biomass conversion and syngas composition. The results from the model for the given conditions are compared to the experimental results and possible reasons for deviations are proposed.