High Selectively Catalytic Conversion of Lignin-Based Phenols into para-/m-Xylene over Pt/HZSM-5

High selectively catalytic conversion of lignin-based phenols (m-cresol,p-cresol, and guaiacol) intopara-/m-xylene was performed over Pt/HZSM-5 through hydrodeoxygenation andin situmethylation with methanol. It is found that thep-/m-xylene selectivity is uniformly higher than 21%, and even increase up to 33.5% form-cresol (with phenols/methanol molar ratio of 1/8). The improvedp-/m-xylene selectivity in presence of methanol is attributed to the combined reaction pathways: methylation ofm-cresol into xylenols followed by HDO intop-/m-xylene, and HDO ofm-cresol into toluene followed by methylation intop-/m-xylene. Comparison of the product distribution over a series of catalysts indicates that both metals and supporters have distinct effect on thep-/m-xylene selectivity.Keywords:m-cresol;hydrodeoxygenation;methanol;p-/m-xylene;methylation