Conversion of bio-derived phenolic compounds into aromatic hydrocarbons by co-feeding methanol over γ-Al2O3

In the present study, a novel route of upgrading lignin pyrolysis vapor to aromatic hydrocarbons was investigated. Guaiacol was used as model compound to investigate the coupling conversion of pyrolysis vapor and methanol. Co-feeding methanol obviously facilitated the conversion of guaiacol to aromatic hydrocarbons and inhibited coke formation. HZSM-5, Al-MCM-41 and gamma-Al2O3 catalysts were screened, and gamma-Al2O3 showed the best catalytic activity for the catalytic co-cracking reaction due to the appropriate acid property. The effects of methanol to guaiacol molar ratio, reaction temperature and W/F-guaiacol on product distribution over gamma-Al2O3 were studied in a fixed bed reactor to reveal the reaction mechanism. As hydrogen donor, the co-fed methanol promoted the deoxygenation of guaiacol. The water formed through methanol dehydration was an efficient agent for attenuating coke deposition. The highest yield of aromatic hydrocarbons was 81.2% when the methanol to guaiacol molar ratio was 25 at 400 degrees C. The investigation of W/F-guaiacol indicated that the synergistic effect of co-feeding was sensitive at lower W/F-guaiacol. Co-feeding methanol with phenol, anisole and the phenolic mixture were also investigated, and high yields of aromatic hydrocarbons were obtained, which demonstrated that co-feeding methanol was a promising process for upgrading complicated pyrolysis products.