In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory eff...In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory effect of layered double hydroxides(LDHs),rehydrated Ca4 Al1-x Gax-LDHs and Ca4 Al1-x Inx-LDHs catalysts were prepared and applied in aldol condensation reaction that isobutyraldehyde(IBD)reacts with formaldehyde(FA)to obtain hydroxypivalaldehyde(HPA).Notably,the resulting re-Ca4 Al0.90Ga0.10-LDHs exhibits an extraordinarily-high catalytic activity(HPA yield:72%),which is to our best knowledge the highest level in this reaction.The weak Br?nsted basic site,7-coordinated Ca-OH group,which serves as an active site,catalyzes the condensation process and promotes the product desorption.Studies on structure-property correlations demonstrate that Ga as a structural promoter induces a moderate expansion of the laminate lattice,which results in a significant increase in the concentration of weak basic sites in re-Ca4Al0.90Ga0.10-LDHs,accounting for its high catalytic activity.This work illuminates that geometric structure of basic active sites can be tuned via introducing catalyst additive,which leads to a largely improved performance of hydrotalcite solid basic catalysts towards aldol condensation reaction.展开更多
文摘In solid basic catalysis field,how to achieve optimized activity and desired stability through elaborate control over basic site properties remains a challenge.In this work,taking advantage of the structure memory effect of layered double hydroxides(LDHs),rehydrated Ca4 Al1-x Gax-LDHs and Ca4 Al1-x Inx-LDHs catalysts were prepared and applied in aldol condensation reaction that isobutyraldehyde(IBD)reacts with formaldehyde(FA)to obtain hydroxypivalaldehyde(HPA).Notably,the resulting re-Ca4 Al0.90Ga0.10-LDHs exhibits an extraordinarily-high catalytic activity(HPA yield:72%),which is to our best knowledge the highest level in this reaction.The weak Br?nsted basic site,7-coordinated Ca-OH group,which serves as an active site,catalyzes the condensation process and promotes the product desorption.Studies on structure-property correlations demonstrate that Ga as a structural promoter induces a moderate expansion of the laminate lattice,which results in a significant increase in the concentration of weak basic sites in re-Ca4Al0.90Ga0.10-LDHs,accounting for its high catalytic activity.This work illuminates that geometric structure of basic active sites can be tuned via introducing catalyst additive,which leads to a largely improved performance of hydrotalcite solid basic catalysts towards aldol condensation reaction.
