Cr_(2)O_(3) has been recognized as a key oxide component in bifunctional catalysts to produce bridging intermediate,e.g.,methanol,from syngas.By combining density functional theory calculations and microkinetic modeli...Cr_(2)O_(3) has been recognized as a key oxide component in bifunctional catalysts to produce bridging intermediate,e.g.,methanol,from syngas.By combining density functional theory calculations and microkinetic modeling,we computationally studied the surface structures and catalytic activities of bare Cr_(2)O_(3)(001)and(012)surfaces,and two reduced(012)surfaces covered with dissociative hydrogens or oxygen vacancies.The reduction of(001)surface is much more difficult than that of(012)surface.The stepwise or the concerted reaction pathways were explored for the syngas to methanol conversion,and the hydrogenation of CO or CHO is identified as rate-determining step.Microkinetic modeling reveals that(001)surface is inactive for the reaction,and the rates of both reduced(012)surfaces(25−28 s^(-1))are about five times higher than bare(012)surface(4.3 s^(-1))at 673 K.These theoretical results highlight the importance of surface reducibility on the reaction and may provide some implications on the design of individual component in bifunctional catalysis.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.92045303)the China Postdoctoral Science Foundation(No.2020M681444).The computational resources from Sinopec Geophysical Research Institute are acknowledged.
文摘Cr_(2)O_(3) has been recognized as a key oxide component in bifunctional catalysts to produce bridging intermediate,e.g.,methanol,from syngas.By combining density functional theory calculations and microkinetic modeling,we computationally studied the surface structures and catalytic activities of bare Cr_(2)O_(3)(001)and(012)surfaces,and two reduced(012)surfaces covered with dissociative hydrogens or oxygen vacancies.The reduction of(001)surface is much more difficult than that of(012)surface.The stepwise or the concerted reaction pathways were explored for the syngas to methanol conversion,and the hydrogenation of CO or CHO is identified as rate-determining step.Microkinetic modeling reveals that(001)surface is inactive for the reaction,and the rates of both reduced(012)surfaces(25−28 s^(-1))are about five times higher than bare(012)surface(4.3 s^(-1))at 673 K.These theoretical results highlight the importance of surface reducibility on the reaction and may provide some implications on the design of individual component in bifunctional catalysis.
