Use of CO2 as a co-reactant to promote syngas production in supercritical water gasification of sugarcane bagasse

In this paper, thermodynamic equilibrium approaches are used to study the effect of CO2 addition, as coreactant in supercritical water gasification (SCWG) of sugarcane bagasse to improve syngas production. The effects of temperature, pressure, biomass composition and co-reactant composition were evaluated under equilibrium compositions for isothermic systems and thermal behavior for adiabatic systems. The CO2 concentration in feed was analyzed at three different mass compositions: 15, 25 and 35 (wt%). The Viriat equation of state was used to represent the non-ideality of both isothermic and adiabatic systems. The problems were formulated as optimization problems (non-linear programing) and the software GAMS with the CONOPT solver were used to solve them. Syngas with a H-2/CO molar ratio close to 2 (ideal for further Fischer-Tropsch synthesis application) was obtained with an addition of CO2 as a co-reactant at 35 wt%. The calculated final temperatures were close to the initial ones, indicating low energy requirements for maintain these reactions. (C) 2015 Published by Elsevier Ltd.