Jie Zhang,Chuang Li,Weixiang Guan,Xiaozhen Chen,Xiao Chen,Chi-Wing Tsang,Changhai Liang
Co(Ni)/MoO 3 catalysts were prepared, characterized and evaluated for the hydrogenolysis of bio-derived dibenzofuran (DBF), aiming at the understanding of the promoting effect of Co/Ni on MoO 3 for high-yield production of aromatic products. All Co(Ni)/MoO 3 catalysts selectively cleaved C-O bond, thus effectively transformed DBF to biphenyl (BP) at relatively moderate conditions. The experimental results from varying Mo species by adjusting the reduction temperature of MoO 3 together with XPS and in-situ XRD characteristic were evident that Mo 5+ species was responsible as the major active specie for the reaction. Promotional effect between Co(Ni) and Mo in Co(Ni)/MoO 3 catalysts was observed, resulted from the presence of acidic Co(Ni)MoO 4 species and a large number of Mo 5+ species both of which were created local to the Co(Ni)-O-Mo interface, as can be characterized by in-situ XRD, XPS, H 2 -TPR, NH 3 -TPD, in-situ FT-IR, Raman and TEM. The trend of the initial reaction rate follows: MoO 3 (0.18 μmol∙g cat −1 ∙s −1 ) < Ni/MoO 3 (0.26 μmol∙g cat −1 ∙s −1 ) < Co/MoO 3 (0.29 μmol∙g cat −1 ∙s −1 ), corresponding to the decreasing activation barrier. And the best catalytic activity was observed for the 100% yield of BP over Co/MoO 3 . A possible mechanism, including Co(Ni) facilitated reduction of Mo 6+ to Mo 5+ and Co(Ni) enhanced formation of acidic sites, is proposed to be responsible for the high activity in Co(Ni)/MoO 3 catalysts.
Shudong Wang,Yuhan Cui,Chenxi Zhao,Changhai Liang,Chuang Li
The hydrothermal stability of supported metal catalysts is one of the greatest challenges in the development of biomass conversion to chemicals and fuels. Herein, a hydrotalcite-based core–shell catalyst (Al2O3@NiMo-LDO) was synthesized by urea precipitation and ion-exchange methods, which could selectively convert bio-oil model compounds to liquid alkanes with high activity and selectivity and excellent hydrothermal stability at low pressure. In the hydrogenation of methyl palmitate, the catalyst afforded 81% conversion and 99% selectivity of n-pentadecane and n-hexadecane under low pressure, with excellent hydrothermal stability. The excellent catalytic performance of Al2O3@NiMo-LDO was attributed to the strong hydrogen activation ability, improvement of the utilization of active components under low pressure, and the increase in the number of active Mo5+ species. The superior hydrothermal stability was attributed to the core–shell structure, which avoided the influence of the specific surface area of Al2O3 that is reduced by the hydration reaction between Al2O3 and H2O at high temperature.
Fengan Han,Yanting Liu,Guangyi Li,Lin Yuan,Aiqin Wang,Feng Wang,Tao Zhang,Ning Li
Selective hydrodeoxygenation (HDO) of lignocellulose-derived ketones to olefins is a promising method for upgrading lignocellulosic biomass-derived molecules. Herein, zinc molybdate (ZnMoO4–E) with a disordered layered stacking structure was first prepared using a facile and environmentally friendly evaporation method and it exhibited outstanding catalytic performance for the selective HDO of lignocellulose-derived ketones to olefins. Using it, 4-heptanone, a representative of lignocellulose-derived ketones, was totally converted, and a high carbon yield of heptene (90%) was achieved at 673 K. On the basis of the characterization results, the outstanding catalytic performance of ZnMoO4–E was attributed to its porous structure, higher oxygen vacancy (or the Mo5+ species) concentration and higher acidity. Analogously, ZnMoO4–E also exhibited good catalytic performances for the selective HDO of other lignocellulose-derived ketones (such as acetone, butanone, 2-pentanone, 3-pentanone, cyclohexanone, acetophenone and 5-nonanone) to their corresponding olefins.
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