A novel route involving self‐metathesis of1‐butene under mild conditions that gave high yields ofethene and hexene was proposed.The results of thermodynamic analysis revealed that the Gibbsenergy of the target Metat...A novel route involving self‐metathesis of1‐butene under mild conditions that gave high yields ofethene and hexene was proposed.The results of thermodynamic analysis revealed that the Gibbsenergy of the target Metathesis I reaction(1‐butene?ethene+3‐hexene)was much higher thanthat of the main side Metathesis II(1‐butene+2‐butene?propene+2‐pentene).Suppression of1‐butene double‐bond isomerization was the key step to increase the selectivity for the target olefinin the reaction network.The relationship between the catalytic performance and support nature was investigated in detail.On basis of H2‐TPR,UV‐Vis spectra and HRTEM results,an alumina(Al2O3)support with large surface area was beneficial for the dispersion of molybdenum(Mo)species.Both suitable acidity and sufficient Mo dispersion were important to selectively promote the self‐metathesis reaction of1‐butene.On the optimal6Mo/Al2O3catalyst,1‐butene conversion reached47%and ethene selectivity was as high as42%on the premise of good catalytic stability(80°C,1.0MPa,3h?1).?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.展开更多
The one-step conversion of ethanol to 1,3-butadiene has achieved a breakthrough with the development of beta zeolite supported dual metal catalysts.However,the reaction mechanism from ethanol to butadiene is complex a...The one-step conversion of ethanol to 1,3-butadiene has achieved a breakthrough with the development of beta zeolite supported dual metal catalysts.However,the reaction mechanism from ethanol to butadiene is complex and has not yet been fully elucidated,and no catalyst screening effort has been done based on central metal atoms.In this work,density functional theory(DFT)calculations were employed to study the mechanism of one-step conversion of ethanol to butadiene over ZnY/BEA catalyst.The results show that ethanol dehydrogenation prefers to proceed on Zn site with a reaction energy of 0.77 eV in the rate-determining step,and the aldol condensation to produce butadiene prefers to proceed on Y site with a reaction energy of 0.69 eV in the rate-determining step.Based on the mechanism revealed,six elements were selected to replace Y for screening superior combination of Zn-M/BEA(M=Sn,Nb,Ta,Hf,Zr,Ti;BEA:beta polymorph A)for this reaction.As a result,Zn-Y/BEA(0.69 eV)is proven to be the most preferring catalyst compared with the other six ones,and Zn-Zr/BEA(0.85 eV),Zn-Ti/BEA(0.87 eV),and Zn-Sn/BEA(0.93 eV)can be potential candidates for the conversion of ethanol to butadiene.This work not only provides mechanistic insights into one-step catalytic conversion of ethanol to butadiene over Zn-Y/BEA catalyst but also offers more promising catalyst candidates for this reaction.展开更多
文摘A novel route involving self‐metathesis of1‐butene under mild conditions that gave high yields ofethene and hexene was proposed.The results of thermodynamic analysis revealed that the Gibbsenergy of the target Metathesis I reaction(1‐butene?ethene+3‐hexene)was much higher thanthat of the main side Metathesis II(1‐butene+2‐butene?propene+2‐pentene).Suppression of1‐butene double‐bond isomerization was the key step to increase the selectivity for the target olefinin the reaction network.The relationship between the catalytic performance and support nature was investigated in detail.On basis of H2‐TPR,UV‐Vis spectra and HRTEM results,an alumina(Al2O3)support with large surface area was beneficial for the dispersion of molybdenum(Mo)species.Both suitable acidity and sufficient Mo dispersion were important to selectively promote the self‐metathesis reaction of1‐butene.On the optimal6Mo/Al2O3catalyst,1‐butene conversion reached47%and ethene selectivity was as high as42%on the premise of good catalytic stability(80°C,1.0MPa,3h?1).?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.
基金This work was supported by the National Natural Science Foundation of China(No.22078257,No.22038011,and No.22108213)the National Key R&D Program of China(No.2020YFA0710000)+1 种基金the China Postdoctoral Science Foundation(No.2018T111034 and No.2021M692548)the Rising Star Program in Science and Technology of Shaanxi Province(No.2020KJXX-079).Chun-Ran Chang also acknowledges the support from the K.C.Wong Education Foundation.The calculations were performed by using the HPC Platform at Xi’an Jiaotong University。
文摘The one-step conversion of ethanol to 1,3-butadiene has achieved a breakthrough with the development of beta zeolite supported dual metal catalysts.However,the reaction mechanism from ethanol to butadiene is complex and has not yet been fully elucidated,and no catalyst screening effort has been done based on central metal atoms.In this work,density functional theory(DFT)calculations were employed to study the mechanism of one-step conversion of ethanol to butadiene over ZnY/BEA catalyst.The results show that ethanol dehydrogenation prefers to proceed on Zn site with a reaction energy of 0.77 eV in the rate-determining step,and the aldol condensation to produce butadiene prefers to proceed on Y site with a reaction energy of 0.69 eV in the rate-determining step.Based on the mechanism revealed,six elements were selected to replace Y for screening superior combination of Zn-M/BEA(M=Sn,Nb,Ta,Hf,Zr,Ti;BEA:beta polymorph A)for this reaction.As a result,Zn-Y/BEA(0.69 eV)is proven to be the most preferring catalyst compared with the other six ones,and Zn-Zr/BEA(0.85 eV),Zn-Ti/BEA(0.87 eV),and Zn-Sn/BEA(0.93 eV)can be potential candidates for the conversion of ethanol to butadiene.This work not only provides mechanistic insights into one-step catalytic conversion of ethanol to butadiene over Zn-Y/BEA catalyst but also offers more promising catalyst candidates for this reaction.
