Interactive effects of phenol, naphthalene and acetic acid during the supercritical water gasification process

Phenol, acetic acid, and naphthalene, as the most common and refractory intermediates during the supercritical water gasification (SCWG) of biomass were selected as the model compounds, and the their mutual interactive effects during the SCWG process were investigated. The gasification performances of one-component solutions and their two- and three-components mixtures were thoroughly studied in a tubular reactor at 550°C, 25 MPa, reaction time of 20 s. Results showed that for the one-component solutions, the difficulty degree of degradation order of the three compounds was naphthalene > phenol > acetic acid, and concentration of the reactants showed little influence on the gasification efficiencies. For the two-components solutions, acetic acid promoted the degradation of phenol and naphthalene, and the gasification of phenol and naphthalene inhibited each other. The 3D curved surface for gas yields and total organic concentration (TOC) removal efficiencies of three-components mixture clearly showed that the increasing concentration of acetic acid increased the H₂ and CO₂ yields. While the interactive effects of the three compounds were favorable for CH₄ yield. Acetic acid played a positive effect on TOC removal, while the increasing concentration of naphthalene was unfavorable for the degradation of TOC, and the inhibition effect was higher when phenol existed.