Preparation Of Few-Layer Structure Molybdenum Sulfide And Its Application In Hydrodeoxygenation Of Lignin

Since lignin is an abundant renewable biomass resource,it can be an alternative to fossil fuels for liquid fuels and value-added chemicals production.Hydrodeoxygenation(HDO)is a chemical reaction which can break the C-O and C-C with the effect of the catalyst under the H2 condition,it has been considered as an effective method for lignin upgrading.This work presented the preparation of hydrotalcite-derived highly dispersed sulfide catalysts and the layer-controlled synthesis of MoS2/AC by thermal decomposition method.The HDO activity of the catalysts on various lignin-derived model compounds with different C-O and C-C structure were also investigated.Firstly,MgFeMo-S catalysts derived from MgFe hydrotalcites with different Mg/Fe mole ratio were prepared,the Mo species was introduced into the interlamination by the hydration of MgFe hydrotalcite oxides with MoO2-4solution.For the HDO of eugenol,Mg1Fe2Mo-S exhibited the best HDO activity among all the catalysts.Under 5 MPa H2 initial pressure(measured at RT)and temperature of 300 °C for 3 h,the conversion of eugenol could reach 100%,and the yield of the main product 4-propylphenol was 44.0%..Compared to MoS2/Mg1Fe2-S catalyst(with 10 wt.% Mo loading)prepared by the impregnation method,it showed significant advantages due to the strong interaction between sulfide species in the layered structure catalyst.In addition,the possible reaction pathway of eugenol was assumed.Further studies were carried on Co and Ni-based hydrotalcites-derived sulfide catalysts according to the similar method.The HDO results of eugenol indicated that Ni-based sulfides showed higher selectivity to benzene hydrogenation.However,Co-based sulfides achieved a high production of phenolic.Co3Al1Mo-S conducted a 100% conversion of eugenol and 47.3% yield of 4-propylphenol under 3 MPa H2 at 300 °C for 3 h.Research on the mechanism of catalytic demonstrated that there exist totally three different active types: Co3O4,CoSx,MoS2 on Co3Al1Mo-S.Finally,supported MoS2/AC with controllable layer numbers were synthesized by adjusting the decomposition temperature of Mo(Et2NCS2)4 precursor.Under decomposition temperature at 400 °C,the MoS2/AC showed a few-layers structure and exhibited the best HDO activity.MoS2/AC-400 °C achieved a 100% conversion of eugenol and 58.3% yield of 4-propylphenol under 5 MPa H2 at 300 °C for 3 h.Moreover,the catalyst exhibited high HDO activity and aromatic selectivity for various lignin-derived compounds.