A selective and efficient process for the electrophilic nitration is described using N_2O_5 as a green nitrating agent,Hβ zeolite as a solid acid catalyst and shape controlling agent under mild conditions.
The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping...The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping on Pt-based catalysts in CO_(2)-ODH reactions.The optimized 0.1 KPt/S-1 catalyst achieved a high propane conversion of 48.3%,propylene selectivity of 85.5%,and CO_(2)conversion of 19.1%at a low temperature of 500℃with the Pt loading of 0.2 wt%and K loading of 0.1 wt%respectively.Characterization techniques,including high-resolution transmission electron microscope(HR-TEM),CO-diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),X-ray absorption fine structure(XAFS),and X-ray Photoelectron Spectroscopy(XPS),revealed that the doping of K with Pt led to a strong interaction between potassium and platinum(Pt-KO_(x)cluster).This interaction resulted in a reduction of Pt particle size and a local enrichment of electron density around Pt atoms.These structural modifications improved the anchoring of Pt nanoparticles and enhanced Pt atom dispersion,thereby enhancing the activity of the catalyst and minimizing side reactions.Additionally,pyridine infrared(Py-IR)and temperature-programmed desorption(TPD)studies demonstrated that the prepared0.1 KPt/S-1 catalyst exhibited optimal acidity,which promoted C–H activation and facilitated the efficient adsorption and activation of CO_(2).These dual effects significantly lowered the activation energy for CO_(2)-ODH,enabling efficient dehydrogenation to propylene at a lower temperature of 500℃.This work highlights the critical role of alkali metal doping in modifying the electronic properties of Pt and optimizing catalyst acidity,which collectively contribute to the enhanced performance of the 0.1 KPt/S-1 catalyst.These findings offer valuable insights into the mechanistic pathway of CO_(2)-ODH and provide a foundation for the rational design of high-performance dehydrogenation catalysts.展开更多
Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5(Si/Al ratio=15)with aqueous solutions of differ-ent Cu precursors(CuCl_(2),Cu(NO_(3))2,CuSO_(4),Cu(CH_(3)COO)2,and ammoniacal copper(II)complex ion).After bei...Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5(Si/Al ratio=15)with aqueous solutions of differ-ent Cu precursors(CuCl_(2),Cu(NO_(3))2,CuSO_(4),Cu(CH_(3)COO)2,and ammoniacal copper(II)complex ion).After being pretreated in flowing He at 500℃to form active Cu+,these catalysts exhibited quite different activities in cata-lytic decomposition of N_(2)O.CZM-AC(II)(prepared by ammoniacal copper(II)complex ion)with 9.4 wt%Cu con-tent was the most active among these Cu-ZSM-5 catalysts,achieving almost complete N_(2)I conversion at 400℃.CZM-CA(prepared using Cu(CH_(3)COO)2 as the Cu precursor)with 2.8 wt%Cu content was the second most active catalyst among these Cu-ZSM-5 catalysts,achieving almost complete N_(2)I conversion at 425℃.CZM-CC,CZM-CN,and CZM-CS prepared by using CuCl_(2),Cu(NO_(3))2,or CuSO_(4)as the Cu precursor with similar Cu contents(≈1.7 wt%)were the least active among these Cu-ZSM-5 catalysts,achieving ca.90%N_(2)O conversion at 500℃.XRD,ICP,SEM,TEM,EDX-mapping,and CO-IR experiments were conducted to characterize relevant samples.The superior activity of CZM-AC(II)can be attributed to the high contents of total Cu+and dimeric Cu+among these samples.The influence of co-fed O2 or H2O on the catalytic performance of typical samples was also studied.展开更多
The precise synthesis of the industrial bactericide N-butyl-1,2.benzisothiazolin-3-one(BBIT)is primarily achieved through catalytic N-alkylation reactions.In this study,a multistep ion-exchange approach was utilized t...The precise synthesis of the industrial bactericide N-butyl-1,2.benzisothiazolin-3-one(BBIT)is primarily achieved through catalytic N-alkylation reactions.In this study,a multistep ion-exchange approach was utilized to produce Cst modified LTA zeolites(Cs-LTA)as precise catalysts for the selective N.alkylation of 1,2-benzisothiazolin-3-one(BIT)using bromobutane,resulting in high-efficiency BBIT synthesis.A systematic optimization of ion-exchange cycles and calcination temperatures facilitated precise control over Cs^(+)dispersion and basic site density within the zeolite framework.XRD,XPS,CO_(2)-TPD,and^(27)Al NMR characterizations verified that the incorporation of Cs^(+)enhanced both the strength of basicity and structural stability through covalent Si-O-Cs bonds,thereby minimizing metal leaching.Under optimized conditions,the Cs-LTA/3 catalyst achieved a BIT conversion rate of 99.21%and a BBIT selectivity of 92.67%.Notably,the catalyst maintained over 80%activity after five cycles,demonstrating superior performance compared to impregnated counterparts.In situ Raman spectroscopy and kinetic analyses revealed a synergistic mechanism:Cs^(+)activates the C-Br bond in bromobutane,producing an electron-deficient alkene intermediate,while the zeolitic basic sites dehydrogenate BIT to generate a nucleophilic amine species,collectively reducing the calcination energy barrier.This research establishes a sustainable catalytic system that overcomes the limitations of homogeneous bases and transition-metal catalysts,providing insights into the strategic design of zeolite-based catalysts for green organic synthesis.展开更多
In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study th...In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study the effect of Fe content in the MFI on the aromatic selectivity.The CO_(2)to aromatics selectivity over H-[Fe]-ZSM-5/ZnO-ZrO_(2)is maximized at Si/Fe ratio=160.At lower Fe contents,the CO_(2)to aromatics selectivity is affected by limiting the Lewis acid site density.At high Fe loadings,the reduction of Fe sites leads to more production of CO and oxygenates.The reduction during pretreatment and reaction provides reduced Fe2+extraframework ions,with the appearance of these species concomitant with enhanced CO and oxygenate formation during the reaction.展开更多
基金the financial support from the National Natural Science Foundation of China-Academy of Engineering Physics(No.10976014)the Natural Science Foundation of Jiangsu Province(No.BK2011697)Independent Scientific Research Special Plan of NJUST(No.2011YBXM06)
文摘A selective and efficient process for the electrophilic nitration is described using N_2O_5 as a green nitrating agent,Hβ zeolite as a solid acid catalyst and shape controlling agent under mild conditions.
基金supported by the National Key Research and Development Program of China(2022YFE0208300)the Natural Science Foundation of China(22078354)。
文摘The oxidative dehydrogenation of propane to propylene using CO_(2)(CO_(2)-ODH)offers a promising route for both propylene production and CO_(2)utilization.In this study,we investigate the effect of alkali metal doping on Pt-based catalysts in CO_(2)-ODH reactions.The optimized 0.1 KPt/S-1 catalyst achieved a high propane conversion of 48.3%,propylene selectivity of 85.5%,and CO_(2)conversion of 19.1%at a low temperature of 500℃with the Pt loading of 0.2 wt%and K loading of 0.1 wt%respectively.Characterization techniques,including high-resolution transmission electron microscope(HR-TEM),CO-diffuse reflectance infrared Fourier transform spectroscopy(CO-DRIFTS),X-ray absorption fine structure(XAFS),and X-ray Photoelectron Spectroscopy(XPS),revealed that the doping of K with Pt led to a strong interaction between potassium and platinum(Pt-KO_(x)cluster).This interaction resulted in a reduction of Pt particle size and a local enrichment of electron density around Pt atoms.These structural modifications improved the anchoring of Pt nanoparticles and enhanced Pt atom dispersion,thereby enhancing the activity of the catalyst and minimizing side reactions.Additionally,pyridine infrared(Py-IR)and temperature-programmed desorption(TPD)studies demonstrated that the prepared0.1 KPt/S-1 catalyst exhibited optimal acidity,which promoted C–H activation and facilitated the efficient adsorption and activation of CO_(2).These dual effects significantly lowered the activation energy for CO_(2)-ODH,enabling efficient dehydrogenation to propylene at a lower temperature of 500℃.This work highlights the critical role of alkali metal doping in modifying the electronic properties of Pt and optimizing catalyst acidity,which collectively contribute to the enhanced performance of the 0.1 KPt/S-1 catalyst.These findings offer valuable insights into the mechanistic pathway of CO_(2)-ODH and provide a foundation for the rational design of high-performance dehydrogenation catalysts.
基金Supported by the National Natural Science Foundation of China(Grant No.21477022)
文摘Five Cu-ZSM-5 catalysts were obtained by treating Na-ZSM-5(Si/Al ratio=15)with aqueous solutions of differ-ent Cu precursors(CuCl_(2),Cu(NO_(3))2,CuSO_(4),Cu(CH_(3)COO)2,and ammoniacal copper(II)complex ion).After being pretreated in flowing He at 500℃to form active Cu+,these catalysts exhibited quite different activities in cata-lytic decomposition of N_(2)O.CZM-AC(II)(prepared by ammoniacal copper(II)complex ion)with 9.4 wt%Cu con-tent was the most active among these Cu-ZSM-5 catalysts,achieving almost complete N_(2)I conversion at 400℃.CZM-CA(prepared using Cu(CH_(3)COO)2 as the Cu precursor)with 2.8 wt%Cu content was the second most active catalyst among these Cu-ZSM-5 catalysts,achieving almost complete N_(2)I conversion at 425℃.CZM-CC,CZM-CN,and CZM-CS prepared by using CuCl_(2),Cu(NO_(3))2,or CuSO_(4)as the Cu precursor with similar Cu contents(≈1.7 wt%)were the least active among these Cu-ZSM-5 catalysts,achieving ca.90%N_(2)O conversion at 500℃.XRD,ICP,SEM,TEM,EDX-mapping,and CO-IR experiments were conducted to characterize relevant samples.The superior activity of CZM-AC(II)can be attributed to the high contents of total Cu+and dimeric Cu+among these samples.The influence of co-fed O2 or H2O on the catalytic performance of typical samples was also studied.
基金funded by the National Natural Science Foundation of China(No.22208349)Shandong Provincial Natural Science Youth Fund(No.ZR2022QB244,ZR2024QB082).
文摘The precise synthesis of the industrial bactericide N-butyl-1,2.benzisothiazolin-3-one(BBIT)is primarily achieved through catalytic N-alkylation reactions.In this study,a multistep ion-exchange approach was utilized to produce Cst modified LTA zeolites(Cs-LTA)as precise catalysts for the selective N.alkylation of 1,2-benzisothiazolin-3-one(BIT)using bromobutane,resulting in high-efficiency BBIT synthesis.A systematic optimization of ion-exchange cycles and calcination temperatures facilitated precise control over Cs^(+)dispersion and basic site density within the zeolite framework.XRD,XPS,CO_(2)-TPD,and^(27)Al NMR characterizations verified that the incorporation of Cs^(+)enhanced both the strength of basicity and structural stability through covalent Si-O-Cs bonds,thereby minimizing metal leaching.Under optimized conditions,the Cs-LTA/3 catalyst achieved a BIT conversion rate of 99.21%and a BBIT selectivity of 92.67%.Notably,the catalyst maintained over 80%activity after five cycles,demonstrating superior performance compared to impregnated counterparts.In situ Raman spectroscopy and kinetic analyses revealed a synergistic mechanism:Cs^(+)activates the C-Br bond in bromobutane,producing an electron-deficient alkene intermediate,while the zeolitic basic sites dehydrogenate BIT to generate a nucleophilic amine species,collectively reducing the calcination energy barrier.This research establishes a sustainable catalytic system that overcomes the limitations of homogeneous bases and transition-metal catalysts,providing insights into the strategic design of zeolite-based catalysts for green organic synthesis.
基金supported by the U.S.Department of Energy,Office of Fossil Energy under Award Number DE-FE0031719Christopher W.Jones acknowledges the John F.BrockⅢChair in Chemical and Biomolecular Engineering at Georgia Tech.This work was performed in part at the Georgia Tech Institute for Matter and Systems,a member of the National Nanotechnology Coordinated Infrastructure,which is supported by the National Science Foundation(ECCS-2025462)+1 种基金This research used beamline 7-BM(QAS)of the National Synchrotron Light SourceⅡ(NSLS-Ⅱ)at Brookhaven National Laboratory(Contract No.DESC0012704)supported in part by the Synchrotron Catalysis Consortium(Grant No.DE-SC0012653).
文摘In this study,H-[Fe]-ZSM-5/ZnO-ZrO_(2)composites are investigated as tandem catalysts for conversion of CO_(2)to mixed aromatic compounds in the presence of H2.Fe-MFI of varying Si/Fe ratios is synthesized to study the effect of Fe content in the MFI on the aromatic selectivity.The CO_(2)to aromatics selectivity over H-[Fe]-ZSM-5/ZnO-ZrO_(2)is maximized at Si/Fe ratio=160.At lower Fe contents,the CO_(2)to aromatics selectivity is affected by limiting the Lewis acid site density.At high Fe loadings,the reduction of Fe sites leads to more production of CO and oxygenates.The reduction during pretreatment and reaction provides reduced Fe2+extraframework ions,with the appearance of these species concomitant with enhanced CO and oxygenate formation during the reaction.
