Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD)...Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)as well as temperature-programmed-reduction by hydrogen(H2-TPR).The catalytic performance of PtFex/CeO_(2),including cinnamaldehyde(CAL)conversion and selectivity toward cinnamyl alcohol(COL),is improved remarkably by introduction of Fe species in the Pt particles in the selective CAL hydrogenation under mild conditions.XPS results indicate that the electron transfer from Fe to Pt promotes CAL adsorption,resulting in the enhanced CAL conversion.And the COL selectivity is improved by CAL adsorption via an interaction of C=O group with surface oxygen defect sites because of interaction between PtFe and CeO_(2)support.In all,this study may provide some hints to design efficient nano Pt particles for the selective hydrogenation.展开更多
Morphological effects of nanoparticles are crucial in many solid-catalyzed chemical transformations.We herein prepared two manganese-ceria solid solutions,well-defined MnCeO_(x)nanorods and MnCeO_(x)-nanocubes,exposin...Morphological effects of nanoparticles are crucial in many solid-catalyzed chemical transformations.We herein prepared two manganese-ceria solid solutions,well-defined MnCeO_(x)nanorods and MnCeO_(x)-nanocubes,exposing preferentially(111)and(100)facets of ceria,respectively.The incorporation of Mn dopant into ceria lattice strongly enhanced the catalytic performance in the NO reduction with CO.MnCeO_(x)(111)catalyst outperformed MnCeO_(x)(100)counterpart due to its higher population density of oxygen vacancy defects.In-situ infrared spectroscopy investigations indicated that the reaction pathway over MnCeO_(x)and pristine CeO_(2)is similar and that besides the direct pathway,an indirect pathway via adsorbed hyponitrite as an intermediate cannot be ruled out.X-ray photoelectron and Raman spectroscopies as well as first-principles density functional theory(DFT)calculations indicate that the enhanced catalytic performance of MnCeO_(x)can be traced back to its“Mn–OL(VÖ)–Mn–OL(VÖ)–Ce”connectivities.The Mn dopant strongly facilitates the formation of surface oxygen vacancies(VÖ)by liberating surface lattice oxygen(OL)via CO*+OL→CO_(2)*+VÖand promotes the reduction of NO,according to NO*+VÖ→N*+OL and 2N*→N_(2).The Mn dopant impact on both the adsorption of CO and activation of OL reveals that a balance between these two effects is critical for facilitating all reaction steps.展开更多
We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%s...We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%selectivity.The catalysts are obtained via precise depositing of CuO nanoclusters(size:~3.5 nm)at the{101}facet of the TiO2 to optimally tune exciton recombination through oxygen vacancies generation,evidenced by photoluminescence and Raman spectroscopy measurements.The turnover frequency(TOF)and the apparent quantum efficiency(AQE)of the 7%CuO/TiO2-spindle composites reach up to 23.8 molmethanol·gcat^-1·h^-1 and 55.2%at 25℃,respectively,which are substantially higher than these previously reported photocatalysts.Further,the in-situ attenuated total reflection infrared spectroscopy analysis reveals that the methanol oxidation most likely takes place through the conversion of adsorbed methoxy(CH30^*)to formaldehyde(CHO^*)intermediate,a subject of major debate for a long time.The adsorbed formaldehyde(CHO^*)thus produced reacts with another CH30^*species in its close proximity to form the final product of methyl formate.Results of this study provide insights into the reaction mechanism,and offer guidelines to systematically develop and apply photocatalysts for methanol conversion and related reactions via surface engineering.展开更多
基金Project supported by the Natural Science Foundation of Inner Mongolia Autonomous Region(2020BS02016)the Program of Higher-level Talents of Inner Mongolia Agricultural University(NDYB2018-23)the Program of Scientific Research of Inner Mongolia Autonomous Region(NJZY19046)。
文摘Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)as well as temperature-programmed-reduction by hydrogen(H2-TPR).The catalytic performance of PtFex/CeO_(2),including cinnamaldehyde(CAL)conversion and selectivity toward cinnamyl alcohol(COL),is improved remarkably by introduction of Fe species in the Pt particles in the selective CAL hydrogenation under mild conditions.XPS results indicate that the electron transfer from Fe to Pt promotes CAL adsorption,resulting in the enhanced CAL conversion.And the COL selectivity is improved by CAL adsorption via an interaction of C=O group with surface oxygen defect sites because of interaction between PtFe and CeO_(2)support.In all,this study may provide some hints to design efficient nano Pt particles for the selective hydrogenation.
基金the National Natural Science Foundation of China(Nos.22065029 and 22172167)the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2022MS02002).
文摘Morphological effects of nanoparticles are crucial in many solid-catalyzed chemical transformations.We herein prepared two manganese-ceria solid solutions,well-defined MnCeO_(x)nanorods and MnCeO_(x)-nanocubes,exposing preferentially(111)and(100)facets of ceria,respectively.The incorporation of Mn dopant into ceria lattice strongly enhanced the catalytic performance in the NO reduction with CO.MnCeO_(x)(111)catalyst outperformed MnCeO_(x)(100)counterpart due to its higher population density of oxygen vacancy defects.In-situ infrared spectroscopy investigations indicated that the reaction pathway over MnCeO_(x)and pristine CeO_(2)is similar and that besides the direct pathway,an indirect pathway via adsorbed hyponitrite as an intermediate cannot be ruled out.X-ray photoelectron and Raman spectroscopies as well as first-principles density functional theory(DFT)calculations indicate that the enhanced catalytic performance of MnCeO_(x)can be traced back to its“Mn–OL(VÖ)–Mn–OL(VÖ)–Ce”connectivities.The Mn dopant strongly facilitates the formation of surface oxygen vacancies(VÖ)by liberating surface lattice oxygen(OL)via CO*+OL→CO_(2)*+VÖand promotes the reduction of NO,according to NO*+VÖ→N*+OL and 2N*→N_(2).The Mn dopant impact on both the adsorption of CO and activation of OL reveals that a balance between these two effects is critical for facilitating all reaction steps.
基金Q.Q.S.thanks the Postdoctoral Science Foundation of China(No.223232),the Natural Science Foundation of Inner Mongolia Autonomous Region(No.2018BS02004)the major special topics of Inner Mongolia science and technology department(No.20181351)+3 种基金Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(No.NJYT-20-B20)the Program of Higher-level Talents of Inner Mongolia Agricultural University(No.NDYB2016-03)LiaoNing Revitalization Talents Program(No.XLYC1807121)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019)for financial support.
文摘We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/Ti02-spindle composite as a promising photocatalyst under mild conditions with over 97%conversion and 83%selectivity.The catalysts are obtained via precise depositing of CuO nanoclusters(size:~3.5 nm)at the{101}facet of the TiO2 to optimally tune exciton recombination through oxygen vacancies generation,evidenced by photoluminescence and Raman spectroscopy measurements.The turnover frequency(TOF)and the apparent quantum efficiency(AQE)of the 7%CuO/TiO2-spindle composites reach up to 23.8 molmethanol·gcat^-1·h^-1 and 55.2%at 25℃,respectively,which are substantially higher than these previously reported photocatalysts.Further,the in-situ attenuated total reflection infrared spectroscopy analysis reveals that the methanol oxidation most likely takes place through the conversion of adsorbed methoxy(CH30^*)to formaldehyde(CHO^*)intermediate,a subject of major debate for a long time.The adsorbed formaldehyde(CHO^*)thus produced reacts with another CH30^*species in its close proximity to form the final product of methyl formate.Results of this study provide insights into the reaction mechanism,and offer guidelines to systematically develop and apply photocatalysts for methanol conversion and related reactions via surface engineering.