Mordenite-supported ruthenium catalyst for selective hydrodeoxygenation of lignin model compounds and lignin-derived bio-oil to produce cycloalkanes

Abstract

Recently high yield of cycloalkanes originates from selective hydrodeoxygenation (HDO) of lignin-derived bio-oil under mild conditions, which still encounters the great challenges. Herein, mordenite-supported ruthenium bifunctional catalyst (Ru3%/M) was prepared by using the deposition-precipitation (DP) method for the HDO reaction of the petroleum ether-extractable portions (PEEP) from alkali catalytic ethanolysis of lignin (CEOL). Ru3%/M catalyst was characterized systematically by XRD, XPS, FTIRS, NH3-TPD, N2-adsorption, SEM, and TEM, indicating that it had the moderate acid sites and uniform Ru nanoparticles dispersion. The synthesized catalyst was further tested for the HDO performance of diphenyl ether, oxybis(methylene)dibenzene, and anisole, respectively. Results showed that three lignin model compounds can be converted to high yield of cycloalkanes under 160 °C and 3 MPa H2 in n-hexane. This catalyst showed the high catalytic activity for diphenyl ether HDO reaction, the conversion decreased slightly to 87.6% after five recycle times. Furthermore, catalyst feed mass was the key factor for HDO reaction of raw PEEP from CEOL, promoting the HDO reaction process to produce high yield of cycloalkanes. Interestingly, the mass ratio between catalyst feed and raw PEEP was 1, thus 74.36% relative content (RC) of cycloalkanes can be obtained. The upgraded PEEP from CEOL has potential to be used as clean liquid fuels.