Production of aromatic hydrocarbons from lignin via catalytic gas-phase pyrolysis over a PtMo/Ti@Si core-shell catalyst

Lignin catalytic pyrolysis-hydrodeoxygenation in gas phase can produce aromatic hydrocarbons in one step. However, the main challenges limiting this process are the selective cleavage of lignin C–O bonds and catalyst deactivation. Here, we propose the design of a highly efficient hydrodeoxygenation catalyst PtMo/Ti@SiO2, which achieves effective lignin catalytic conversion. Pt and Mo respectively function in hydrogen activation and C–O bond activation, and their cooperation significantly promotes the hydrodeoxygenation of guaiacol (deoxygenation ratio increased from 31% to 95%), and the deoxygenation efficiency of the intermediate product phenol is significantly improved. The nano TiO2 carrier exhibits smaller crystallite size and abundant oxygen vacancies, demonstrating superior hydrodeoxygenation activity over catalysts with other supports. By introducing a protective SiO2 shell layer, the active sites of the catalyst are preserved, reducing coke deposition on the catalyst surface from lignin and its derived phenolics, and increasing the yield of monomeric aromatic hydrocarbons produced from lignin catalytic pyrolysis by 34.4%. In addition, the liquid-phase aromatic hydrocarbon selectivity reaches 100%. Furthermore, this catalyst achieves efficiently converts various types of lignin into monomeric aromatic hydrocarbons, providing an efficient and feasible strategy for gaseous-phase catalytic conversion of lignin.