Ultrafast microfluidic preparation of highly dispersed Ru/TiO2 catalyst for the hydrodeoxygenation of lignin-derived phenolic compounds.

• A novel photochemical method coupled with microfluidic technology was proposed. • Highly dispersed Ru/TiO 2 catalyst enabled to be obtained within only 1 min. • An enhanced mass transfer can be achieved during the preparation process. • A strong interaction between Ru and TiO 2 resulted in more spillover hydrogen. • Hydrocarbon content in lignin-oil increased from 6.7% to 69.5% after HDO. An ultrafast preparation method that coupled the photochemical method with the microfluidic technology to synthesize the highly dispersed Ru/TiO 2 catalyst within only 1 min was proposed. This method had an enhanced electron excitation and a high electron transfer efficiency during the preparation process due to the small dimension of the microchannel, which enabled to shorten the preparation time greatly. Much higher metal reduction efficiency was obtained than that of the single photochemical method, and a high Ru metal dispersion on the TiO 2 surface can be achieved. Moreover, a strong interaction between the metal site and the support was formed, resulting in more spillover hydrogen. This Ru/TiO 2 catalyst presented a high activity on the HDO of phenolic compounds. Guaiacol was converted into cyclohexane with 97.6 % selectivity at 260 °C. The raw lignin-oil also can be upgraded efficiently, with the hydrocarbon content increased from 6.7 % to 69.4 %. [ABSTRACT FROM AUTHOR]