(157b) Bio-Oil Upgrading Using Methane: A Mechanistic Study of Model Compound Guaiacol Reactions over Pt-Bi Bimetallic Catalysts

Biomass and shale/natural gas are two important alternative resources for fuels and chemicals production for at least the next century. Bio-oil, deriving from fast pyrolysis of lignin, is a key second generation bio-fuel, containing high oxygen content. Hydrodeoxygenation (HDO) is typically employed to improve the quality of bio-oils, while high cost of hydrogen prevents its commercialization. On the other hand, although it is the primary component of shale and natural gas, methane direct conversion to higher hydrocarbons remains as a challenge since the 1980s. Following our recent work, in the present study, methane is used to upgrade guaiacol, a well-known model compound of bio-oils, over Pt-Bi bimetallic catalysts supported on activated carbon. Various characterization techniques, including TEM, XRD, BET, H₂-TPD, H₂-O₂ titration, AES-ICP, TPO and TPSR, were utilized to obtain catalyst structure and properties. It was found that Pt-Bi bimetallic catalysts exhibit stable guaiacol upgrading performance for 8 hours TOS, generating partially deoxygenated products along with ethane. The addition of Bi blocks some surface Pt atoms functioning as active sites and suppresses coke formation. The isotopic labeling tests demonstrated that ethane is produced either from coupling of two methane molecules (20-25%) or a methane molecule combining with a methyl from guaiacol (75-80%). The present work provides the conceptual framework for an integrated process of catalytic bio-oil upgrading along with shale/natural gas utilization.