In the dehydration of fructose to 5-hydroxymethyl furfural(HMF),in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF,causing unsatisfactory catalytic activity and selectiv...In the dehydration of fructose to 5-hydroxymethyl furfural(HMF),in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF,causing unsatisfactory catalytic activity and selectivity.In this work,a class of benzenesulfonic acid-grafted metal-organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating agent.The resultant MOFs have a specific surface area of greater than 250 m^(2)·g^(-1),acid density above 1.0 mmol·g^(-1),and water contact angle up to 129°.The hydrophobic MOF-PhSO_(3)H exhibits both higher catalytic activity and selectivity than MOF-SO_(3)H in the HMF synthesis due to its better hydrophobicity and olephilicity.Moreover,the catalyst has a high recycled stability.At last,fructose is completely converted,and 98.0%yield of HMF is obtained under 120℃ in a DMSO solvent system.The successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF.展开更多
A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu:Pd atomic ratios were prepared by conventionally sequential impregnation(CSD)and modified sequential impregnation(MSI)of Cu and Pd for...A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu:Pd atomic ratios were prepared by conventionally sequential impregnation(CSD)and modified sequential impregnation(MSI)of Cu and Pd for selective hydrogenation of acetylene.Characterization indicates that the supported copper(I)nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO3)2 crystals.In addition,for the catalysts prepared by MSI,Pd atoms can form PdCu alloy on the surface of metal particles,however,for the catalysts prepared by CSI,Pd tends to migrate and exist below the surface layer of Cu.Reaction results indicate that compared with CSI,the MSI method enables samples to possess preferable stability as well as comparable reaction activity.This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles.Moreover,even Pd loading is super low,<0.045 wt-%in this study,by through adjusting Cu loading to an appropriate value,attractive reactivity and selectivity still can be achieved.展开更多
Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in exce...Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.展开更多
基金The authors appreciate support from the National Natural Science Foundation of China(21878138,21706112)the Postdoctoral Science Foundation of China(2017M622104,2018T110660)+1 种基金the Key Scientific and Technological Project of Henan Province(182102410072)the start-up funds from Nanchang University and Arizona State University.
文摘In the dehydration of fructose to 5-hydroxymethyl furfural(HMF),in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF,causing unsatisfactory catalytic activity and selectivity.In this work,a class of benzenesulfonic acid-grafted metal-organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating agent.The resultant MOFs have a specific surface area of greater than 250 m^(2)·g^(-1),acid density above 1.0 mmol·g^(-1),and water contact angle up to 129°.The hydrophobic MOF-PhSO_(3)H exhibits both higher catalytic activity and selectivity than MOF-SO_(3)H in the HMF synthesis due to its better hydrophobicity and olephilicity.Moreover,the catalyst has a high recycled stability.At last,fructose is completely converted,and 98.0%yield of HMF is obtained under 120℃ in a DMSO solvent system.The successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF.
基金support of the National Natural Science Foundation of China(Grant No.1263094)Welch Foundation(No.T-0014)+1 种基金Key Scientific and Technological Projcct of Henan province,China(No.182102410072)Shanxi International Cooperation Project(No.201703D421037)。
文摘A series of PdCu bimetallic catalysts with low Cu and Pd loadings and different Cu:Pd atomic ratios were prepared by conventionally sequential impregnation(CSD)and modified sequential impregnation(MSI)of Cu and Pd for selective hydrogenation of acetylene.Characterization indicates that the supported copper(I)nitrate in the PdCu bimetallic catalysts prepared by MSI can be directly reduced to Cu metal particles due to the hydrogen spillover from Pd to Cu(NO3)2 crystals.In addition,for the catalysts prepared by MSI,Pd atoms can form PdCu alloy on the surface of metal particles,however,for the catalysts prepared by CSI,Pd tends to migrate and exist below the surface layer of Cu.Reaction results indicate that compared with CSI,the MSI method enables samples to possess preferable stability as well as comparable reaction activity.This should be due to the MSI method in favor of the formation of PdCu alloy on the surface of metal particles.Moreover,even Pd loading is super low,<0.045 wt-%in this study,by through adjusting Cu loading to an appropriate value,attractive reactivity and selectivity still can be achieved.
文摘Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.
