The selective activation of C-H bonds is pivotal in catalysis for converting hydrocarbons into value-added chemicals.Ethylbenzene dehydrogenation to styrene is crucial process to produce polystyrene and its derivative...The selective activation of C-H bonds is pivotal in catalysis for converting hydrocarbons into value-added chemicals.Ethylbenzene dehydrogenation to styrene is crucial process to produce polystyrene and its derivatives used in synthetic materials.Herein,K-Cr@Y with zeolite-encaged isolated O=Cr(VI)=O species modified by extraframework potassium ions is constructed,showing remarkable performance in CO_(2)-promoted ethylbenzene dehydrogenation with initial ethylbenzene conversion of 66%and styrene selectivity of 96%,outperforming other M-Cr@Y catalysts(M=Li,Na,Rb,Cs).Extraframework potassium ions can modulate the electron density of zeolite-encaged Cr(VI)species and therefore facilitate C–H bond activation in ethylbenzene molecules.The gradual reduction of zeolite-encaged O=Cr(VI)=O to less active Cr(IV)=O species by dihydrogen during ethylbenzene dehydrogenation is evidenced by comprehensive characterization results,and Cr(IV)=O can be re-oxidized to O=Cr(VI)=O species upon simple calcination regeneration.The results from in situ DRIFT spectroscopy elucidate the critical promotion role of CO_(2)in ethylbenzene dehydrogenation over K-Cr@Y by retarding the over-reduction of zeolite-encaged Cr species to inactive Cr(III)species and suppressing coke deposition.This study advances the rational design of non-noble metal catalysts for CO_(2)-promoted ethylbenzene dehydrogenation with zeolite-encaged high valence transition metal ions modulated by extraframework cations.展开更多
Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promo...Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.展开更多
An efficient one-pot synthetic protocol was developed for the synthesis of imidazo[ 1,2-a]pyridines from easily available starting materials： Aromatic ketones, α/βunsaturated ketones,β-keto esters and 2- aminopyri...An efficient one-pot synthetic protocol was developed for the synthesis of imidazo[ 1,2-a]pyridines from easily available starting materials： Aromatic ketones, α/βunsaturated ketones,β-keto esters and 2- aminopyridines. The present reaction proceeded well in MeOH under the media of I2/CuO. By using this method, the marketed drug zolimidine could be prepared easily with 95% yield. All these target products were characterized by NMR, HRMS and IR spectra. Furthermore, the target compound 3fa was determined bv X-ray crystallographic analysis.展开更多
The selective conversion of CO_(2)and NH_(3)into valuable nitriles presents significant potential for CO_(2)utilization.In this study,we exploited the synergistic interplay between silicon and fluoride to augment the ...The selective conversion of CO_(2)and NH_(3)into valuable nitriles presents significant potential for CO_(2)utilization.In this study,we exploited the synergistic interplay between silicon and fluoride to augment the nickel-catalyzed reductive cyanation of aryl pseudohalides containing silyl groups,utilizing CO_(2)and NH_(3)as the CN source.Our methodology exhibited exceptional compatibility with diverse functional groups,such as alcohols,ketones,ethers,esters,nitriles,olefins,pyridines,and quinolines,among others,as demonstrated by the successful synthesis of 58 different nitriles.Notably,we achieved high yields in the preparation of bifunctionalized molecules,including intermediates for perampanel,derived from osilylaryl triflates,which are well-known as aryne precursors.Remarkably,no degradation of substrates or formation of aryne intermediates were observed.Mechanistic studies imply that the formation of pentacoordinated silyl isocyanate intermediates is crucial for the key C-C coupling step and the presence of vicinal silyl group in the substrate is beneficial to further make this step kinetically favorable.展开更多
MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)ha...MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)has achieved remarkable results.However,these studies require high-speed ball milling(400-500 rpm)to achieve the combination of MgH_(2)and catalyst,and such harsh processing conditions are difficult to achieve in industrial production.In this work,the catalyst and MgH_(2)were efficiently combined at lower milling speed(300 rpm)by introducing tetrahydrofuran C4H8O(THF)as an auxiliary agent.Moreover,milling with THF promotes the nanocrystallization of MgH_(2),which further improves its performance.Results show that THF-assisted MgH_(2)absorbed 6.1 wt%at 90℃and desorbed 6.1 wt%at 275℃,while the MgH_(2)milling under the same speed without THF cannot absorb hydrogen and only desorbed 3.3 wt%.It reveals that the synergistic effect produced by nano-crystallization and nano-hydrogen pump is the key mechanism of improving the performance of MgH_(2)after introducing THF.This work proposes a novel synergistic strategy for modifying MgH_(2),offering practical insights for enhancing its hydrogen storage performance under low-speed ball milling.展开更多
Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogena...Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogenation reaction,involving surface carbonate hydrogenation and CO_(2)chemisorption.Nonetheless,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic CO_(2)conversion.This work demonstrated that the incorporation of CaH_(2)in Ni/CaCO_(3)enhances the CO_(2)methanation activity of the catalysts.The CO_(2)conversion for Ni/CaH_(2)-CaCO_(3)reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO_(3)(31.6%) and Ni/CaH_(2)-CaO (42.4%) catalysts.Furthermore,the Ni/CaH_(2)-CaCO_(3)catalysts remained stable during the stability test for 24 h at 400°C and 8 bar.Our research revealed that CaH_(2)played a crucial role in promoting the activity of the Ni-carbonate interface for CO_(2)methanation.CaH_(2)could modify the electronic structure of Ni and tune the structural properties of CaCO_(3)to generate medium basic sites (OH groups),which are favorable for the activation of H2and CO_(2).In-situ Fourier transform infrared spectroscopy (FTIR) analysis combined with density functional theory calculations demonstrated that CO_(2)activation occurs at the hydroxyl group (OH) on the CaH_(2)-modified Ni-carbonate surface,leading to the formation of CO_(3)H*species.Furthermore,our study has confirmed that CO_(2)methanation over the Ni/CaH_(2)-CaCO_(3)catalysts proceeds via the formate pathway.展开更多
文摘The selective activation of C-H bonds is pivotal in catalysis for converting hydrocarbons into value-added chemicals.Ethylbenzene dehydrogenation to styrene is crucial process to produce polystyrene and its derivatives used in synthetic materials.Herein,K-Cr@Y with zeolite-encaged isolated O=Cr(VI)=O species modified by extraframework potassium ions is constructed,showing remarkable performance in CO_(2)-promoted ethylbenzene dehydrogenation with initial ethylbenzene conversion of 66%and styrene selectivity of 96%,outperforming other M-Cr@Y catalysts(M=Li,Na,Rb,Cs).Extraframework potassium ions can modulate the electron density of zeolite-encaged Cr(VI)species and therefore facilitate C–H bond activation in ethylbenzene molecules.The gradual reduction of zeolite-encaged O=Cr(VI)=O to less active Cr(IV)=O species by dihydrogen during ethylbenzene dehydrogenation is evidenced by comprehensive characterization results,and Cr(IV)=O can be re-oxidized to O=Cr(VI)=O species upon simple calcination regeneration.The results from in situ DRIFT spectroscopy elucidate the critical promotion role of CO_(2)in ethylbenzene dehydrogenation over K-Cr@Y by retarding the over-reduction of zeolite-encaged Cr species to inactive Cr(III)species and suppressing coke deposition.This study advances the rational design of non-noble metal catalysts for CO_(2)-promoted ethylbenzene dehydrogenation with zeolite-encaged high valence transition metal ions modulated by extraframework cations.
基金the support from National Key R&D Program of China (2021YFC2103704)the National Natural Science Foundation of China (22222808)+4 种基金the Natural Science Foundation of Shandong Province (ZR2023QB152)the Youth Innovation Team Plan of Shandong Province (2022KJ270)the China National Postdoctoral Program for Innovative Talents (BX20240251)the Aeronautical Science Foundation of China (2023Z073048003)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.
基金the National Natural Science Foundation of China (Nos. 21032001 and 21272085) for their generous financial supportthe excellent doctorial dissertation cultivation grant from Central China Normal University Wuhan, China (No. 2013YBYB63)
文摘An efficient one-pot synthetic protocol was developed for the synthesis of imidazo[ 1,2-a]pyridines from easily available starting materials： Aromatic ketones, α/βunsaturated ketones,β-keto esters and 2- aminopyridines. The present reaction proceeded well in MeOH under the media of I2/CuO. By using this method, the marketed drug zolimidine could be prepared easily with 95% yield. All these target products were characterized by NMR, HRMS and IR spectra. Furthermore, the target compound 3fa was determined bv X-ray crystallographic analysis.
基金the National Natural Science Foundation of China(Nos.22072167,22202218)the Jiangsu Natural Science Funds for Young Scholar(No.BK20211093)is greatly appreciated.
文摘The selective conversion of CO_(2)and NH_(3)into valuable nitriles presents significant potential for CO_(2)utilization.In this study,we exploited the synergistic interplay between silicon and fluoride to augment the nickel-catalyzed reductive cyanation of aryl pseudohalides containing silyl groups,utilizing CO_(2)and NH_(3)as the CN source.Our methodology exhibited exceptional compatibility with diverse functional groups,such as alcohols,ketones,ethers,esters,nitriles,olefins,pyridines,and quinolines,among others,as demonstrated by the successful synthesis of 58 different nitriles.Notably,we achieved high yields in the preparation of bifunctionalized molecules,including intermediates for perampanel,derived from osilylaryl triflates,which are well-known as aryne precursors.Remarkably,no degradation of substrates or formation of aryne intermediates were observed.Mechanistic studies imply that the formation of pentacoordinated silyl isocyanate intermediates is crucial for the key C-C coupling step and the presence of vicinal silyl group in the substrate is beneficial to further make this step kinetically favorable.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LQ24E010003)the Baima Lake Laboratory Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(Nos.LBMHY24E060004,LBMHY24E060005)
文摘MgH_(2)is a promising solid-state hydrogen storage material;one of the limitations of its scale-application is the slow rate of hydrogen uptake and release.The addition of catalyst to improve the kinetics of MgH_(2)has achieved remarkable results.However,these studies require high-speed ball milling(400-500 rpm)to achieve the combination of MgH_(2)and catalyst,and such harsh processing conditions are difficult to achieve in industrial production.In this work,the catalyst and MgH_(2)were efficiently combined at lower milling speed(300 rpm)by introducing tetrahydrofuran C4H8O(THF)as an auxiliary agent.Moreover,milling with THF promotes the nanocrystallization of MgH_(2),which further improves its performance.Results show that THF-assisted MgH_(2)absorbed 6.1 wt%at 90℃and desorbed 6.1 wt%at 275℃,while the MgH_(2)milling under the same speed without THF cannot absorb hydrogen and only desorbed 3.3 wt%.It reveals that the synergistic effect produced by nano-crystallization and nano-hydrogen pump is the key mechanism of improving the performance of MgH_(2)after introducing THF.This work proposes a novel synergistic strategy for modifying MgH_(2),offering practical insights for enhancing its hydrogen storage performance under low-speed ball milling.
基金National Natural Science Foundation of China (Nos. 22371244 and 21573192)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_3463)。
文摘Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogenation reaction,involving surface carbonate hydrogenation and CO_(2)chemisorption.Nonetheless,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic CO_(2)conversion.This work demonstrated that the incorporation of CaH_(2)in Ni/CaCO_(3)enhances the CO_(2)methanation activity of the catalysts.The CO_(2)conversion for Ni/CaH_(2)-CaCO_(3)reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO_(3)(31.6%) and Ni/CaH_(2)-CaO (42.4%) catalysts.Furthermore,the Ni/CaH_(2)-CaCO_(3)catalysts remained stable during the stability test for 24 h at 400°C and 8 bar.Our research revealed that CaH_(2)played a crucial role in promoting the activity of the Ni-carbonate interface for CO_(2)methanation.CaH_(2)could modify the electronic structure of Ni and tune the structural properties of CaCO_(3)to generate medium basic sites (OH groups),which are favorable for the activation of H2and CO_(2).In-situ Fourier transform infrared spectroscopy (FTIR) analysis combined with density functional theory calculations demonstrated that CO_(2)activation occurs at the hydroxyl group (OH) on the CaH_(2)-modified Ni-carbonate surface,leading to the formation of CO_(3)H*species.Furthermore,our study has confirmed that CO_(2)methanation over the Ni/CaH_(2)-CaCO_(3)catalysts proceeds via the formate pathway.
