Effect of the strong metal-support interaction on the hydrodeoxygenation of dibenzofuran
As an important product of coal pyrolysis,coal tar has the characteristics of large output and wide application.The rational and efficient use of medium and low temperature coal tar can promote the clean and efficient conversion of coal resources.The removal of oxy-gen atoms from medium and low temperature coal tar is achieved by catalytic hydrodeoxygenation,which improves the hydrogen/carbon ra-tio and stability of the oil to obtain a high-quality fuel.Dibenzofuran was characterized by its high content and low reactivity,which was chosen as a model compound for the hydrodeoxygenation reaction study in this study.Modulation of Strong Metal-Support Interactions(SMSI)is widely used in heterogeneous catalysis field,but its effect on the hydrodeoxygenation is unclear.To investigate the effect of SM-SI on the hydrodeoxygenation,nickel-titanium-zirconium layered double hydroxides were used as catalyst precursors,and Ni-based cata-lysts(denoted as Ni/m ZrO2@TiO2-x,m=0-0.5)with different SMSI were prepared for the hydrodeoxygenation reaction of the coal tar model compound dibenzofuran by varying the Zr ratio.Characterization by HRTEM,H2-TPD and CO-pulse show that after high tem-perature calcination of the precursors,during the reduction process,part of the support is reduced to TiO2-x to form an encapsulation layer on the surface of the Ni particles,and oxygen vacancies are simultaneously generated.As the Zr ratio increases,the SMSI strength decrea-ses,resulting in a decrease in the encapsulation and oxygen vacancy content.The activity of the catalysts with different SMSI strengths was evaluated and it was found that the yield of the deoxygenated product increased from 60.7%to 94.8%and then decreased to 66.9%with decreasing SMSI strength(increasing Zrratio)at280℃and6 MPa.The Ni/0.4ZrO2@TiO2-x catalyst exhibites the highest deoxygenation performance,which show no decrease in activity after 5 cycles,indicating good stability.The results show that the hydrodeoxygenation per-formance of the catalyst is determined by the combination of encapsulation and oxygen vacancy vacancies by SMSI on the catalyst,with the degree of Ni encapsulation negatively correlated with the hydrogenation performance and the oxygen vacancy content positively correlated with the deoxygenation performance.
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