Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been ...Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been investigated on a model Ni/In_(2)O_(3) catalyst,i.e.,Ni_(4)/In_(2)O_(3),via the density functional theory(DFT)study.Three possible reaction pathways,i.e.,the formate pathway,CO hydrogenation and the reverse water-gas-shift(RWGS)pathways,have been examined on this model catalyst.It has been demonstrated that the RWGS pathway is the most theoretically-favored for CO_(2) hydrogenation to methanol.The complete RWGS pathway follows CO_(2)+6 H→COOH+5 H→CO+H_(2)O+4 H→HCO+H_(2)O+3 H→H_(2)CO+H_(2)O+2 H→H_(3)CO+H_(2)O+H→H_(3)COH+H_(2) O.Furthermore,it has been also proved that the interfacial oxygen vacancy can serve as the active site for boosting the CO_(2) adsorption and charge transfer between the nickel species and indium oxide,which synergistically promotes the consecutive CO_(2) hydrogenation towards methanol.展开更多
The separation of CO_(2)/C_(2)H_(2)mixture by CO_(2)-selective sorbents is an energy-efficient C_(2)H_(2)purification technique,but is strategically challenging due to their similar molecular size and physicochemical ...The separation of CO_(2)/C_(2)H_(2)mixture by CO_(2)-selective sorbents is an energy-efficient C_(2)H_(2)purification technique,but is strategically challenging due to their similar molecular size and physicochemical properties.Meanwhile,water is inevitable in CO_(2)/C_(2)H_(2)mixture and it is usually a significant barrier because of its competitive adsorption with CO_(2).To address this challenge,herein,we report the first example of metal–organic framework(MOF)that exhibits water-boosted CO_(2)adsorption and CO_(2)/C_(2)H_(2)separation by anchoring L-arginine(ARG)on the Zr6 cluster of MOF-808.The CO_(2)affinity and capacity in the resulting MOF-808-ARG are markedly facilitated by the presence of water,while the C_(2)H_(2)adsorption is significantly suppressed.Specifically,CO_(2)adsorption capacities in adsorption isotherm and breakthrough measurement are increased to 143%and 184%,respectively.In addition,the wet MOF-808-ARG exhibits the record CO_(2)/C_(2)H_(2)selectivity of 1,180 under zero coverage.Breakthrough experiments reveal that CO_(2)/C_(2)H_(2)mixture can be completely separated and the result of mass spectrometry indicates that the C_(2)H_(2)purity in the outlet is up to 99.9%.In situ infrared(IR)results and density functional theory(DFT)calculations reveal the water-promoted CO_(2)adsorption mechanism that the formation of bicarbonate products in the presence of water is thermodynamically and kinetically more favorable than that without water.Moreover,MOF-808-ARG also possesses excellent water stability and excellent regeneration of CO_(2)adsorption.This work provides a new paradigm by transforming the negative effects of water into positive ones for CO_(2)/C_(2)H_(2)separation.展开更多
The introduction of mesoporosity into the microporous metal-organic frameworks(MOFs)is expected to expand their applications.Herein,we report a green and facile method to obtain hierarchically porous MOF structures by...The introduction of mesoporosity into the microporous metal-organic frameworks(MOFs)is expected to expand their applications.Herein,we report a green and facile method to obtain hierarchically porous MOF structures by using an air-steam etching process.By virtue of the protonation reaction between the imidazole moiety and water vapor,the protonated imidazole related linkers leave the framework,resulting in the formation of mesopores in the zeolitic imidazolate frameworks(ZIFs),as exemplified by ZIF-8.Given the mild etching process,the materials'structural integrity and crystallinity are well maintained.Accordingly,the hierarchical porous ZIF-8 exhibited enhanced performance in the dye removal as well as CO_(2) cycloaddition reaction with epichlorohydrin in comparison with microporous ZIF-8,owing to the accelerated mass transfer arising from mesoporous structures.Remarkably,the proposed steam etching approach is generally applicable,which can be readily extended to other ZIFs,such as ZIF-14,ZIF-69,and ZIF-71,thus representing a powerful strategy to construct hierarchically porous MOF materials.展开更多
We propose a multidimensional filter SQP algorithm.The multidimensional filter technique proposed by Gould et al.[SIAM J.Optim.,2005]is extended to solve constrained optimization problems.In our proposed algorithm,the...We propose a multidimensional filter SQP algorithm.The multidimensional filter technique proposed by Gould et al.[SIAM J.Optim.,2005]is extended to solve constrained optimization problems.In our proposed algorithm,the constraints are partitioned into several parts,and the entry of our filter consists of these different parts.Not only the criteria for accepting a trial step would be relaxed,but the individual behavior of each part of constraints is considered.One feature is that the undesirable link between the objective function and the constraint violation in the filter acceptance criteria disappears.The other is that feasibility restoration phases are unnecessary because a consistent quadratic programming subproblem is used.We prove that our algorithm is globally convergent to KKT points under the constant positive generators(CPG)condition which is weaker than the well-known Mangasarian-Fromovitz constraint qualification(MFCQ)and the constant positive linear dependence(CPLD).Numerical results are presented to show the efficiency of the algorithm.展开更多
Herein,a novel sensor(TPE-UiO-66)was designed via anchoring monodentate tetraphenylethylene(TPE)onto UiO-66 framework.The combination of the distinct aggregation-induced emission(AIE)of TPE and the easy replacement of...Herein,a novel sensor(TPE-UiO-66)was designed via anchoring monodentate tetraphenylethylene(TPE)onto UiO-66 framework.The combination of the distinct aggregation-induced emission(AIE)of TPE and the easy replacement of monodentate linker by guest phosphate,makes TPE-UiO-66 an ideal pltform for sensing HPO_(4)^(2-)。Experimental results indicate that TPE-UiO-66 can selectively sense HPO_(4)^(2-)from other common anions.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21536008 and 21621004).
文摘Indium oxide supported nickel catalyst has been experimentally confirmed to be highly active for CO_(2) hydrogenation towards methanol.In this work,the reaction mechanism for CO_(2) hydrogenation to methanol has been investigated on a model Ni/In_(2)O_(3) catalyst,i.e.,Ni_(4)/In_(2)O_(3),via the density functional theory(DFT)study.Three possible reaction pathways,i.e.,the formate pathway,CO hydrogenation and the reverse water-gas-shift(RWGS)pathways,have been examined on this model catalyst.It has been demonstrated that the RWGS pathway is the most theoretically-favored for CO_(2) hydrogenation to methanol.The complete RWGS pathway follows CO_(2)+6 H→COOH+5 H→CO+H_(2)O+4 H→HCO+H_(2)O+3 H→H_(2)CO+H_(2)O+2 H→H_(3)CO+H_(2)O+H→H_(3)COH+H_(2) O.Furthermore,it has been also proved that the interfacial oxygen vacancy can serve as the active site for boosting the CO_(2) adsorption and charge transfer between the nickel species and indium oxide,which synergistically promotes the consecutive CO_(2) hydrogenation towards methanol.
基金National Natural Science Foundation of China(Nos.22038010,22141001,and 21978212)the Science and Technology Plans of Tianjin(Nos.21ZYJDJC00040 and 20ZYJDJC00110).
文摘The separation of CO_(2)/C_(2)H_(2)mixture by CO_(2)-selective sorbents is an energy-efficient C_(2)H_(2)purification technique,but is strategically challenging due to their similar molecular size and physicochemical properties.Meanwhile,water is inevitable in CO_(2)/C_(2)H_(2)mixture and it is usually a significant barrier because of its competitive adsorption with CO_(2).To address this challenge,herein,we report the first example of metal–organic framework(MOF)that exhibits water-boosted CO_(2)adsorption and CO_(2)/C_(2)H_(2)separation by anchoring L-arginine(ARG)on the Zr6 cluster of MOF-808.The CO_(2)affinity and capacity in the resulting MOF-808-ARG are markedly facilitated by the presence of water,while the C_(2)H_(2)adsorption is significantly suppressed.Specifically,CO_(2)adsorption capacities in adsorption isotherm and breakthrough measurement are increased to 143%and 184%,respectively.In addition,the wet MOF-808-ARG exhibits the record CO_(2)/C_(2)H_(2)selectivity of 1,180 under zero coverage.Breakthrough experiments reveal that CO_(2)/C_(2)H_(2)mixture can be completely separated and the result of mass spectrometry indicates that the C_(2)H_(2)purity in the outlet is up to 99.9%.In situ infrared(IR)results and density functional theory(DFT)calculations reveal the water-promoted CO_(2)adsorption mechanism that the formation of bicarbonate products in the presence of water is thermodynamically and kinetically more favorable than that without water.Moreover,MOF-808-ARG also possesses excellent water stability and excellent regeneration of CO_(2)adsorption.This work provides a new paradigm by transforming the negative effects of water into positive ones for CO_(2)/C_(2)H_(2)separation.
基金National Key Projects for Fundamental Research and Development of China(No.2016YFB0600901)the National Natural Science Foundation of China(Nos.22038010,21536001,21878229 and 21978212)the Science and Technology Plans of Tianjin(Nos.19PTSYJC00020 and 20ZYJDJC00110).
文摘The introduction of mesoporosity into the microporous metal-organic frameworks(MOFs)is expected to expand their applications.Herein,we report a green and facile method to obtain hierarchically porous MOF structures by using an air-steam etching process.By virtue of the protonation reaction between the imidazole moiety and water vapor,the protonated imidazole related linkers leave the framework,resulting in the formation of mesopores in the zeolitic imidazolate frameworks(ZIFs),as exemplified by ZIF-8.Given the mild etching process,the materials'structural integrity and crystallinity are well maintained.Accordingly,the hierarchical porous ZIF-8 exhibited enhanced performance in the dye removal as well as CO_(2) cycloaddition reaction with epichlorohydrin in comparison with microporous ZIF-8,owing to the accelerated mass transfer arising from mesoporous structures.Remarkably,the proposed steam etching approach is generally applicable,which can be readily extended to other ZIFs,such as ZIF-14,ZIF-69,and ZIF-71,thus representing a powerful strategy to construct hierarchically porous MOF materials.
基金This work is supported by National Science Founda-tion of China(No.11601318)Equipment Manufacturing Systems and Optimization(No.13XKJC01).
文摘We propose a multidimensional filter SQP algorithm.The multidimensional filter technique proposed by Gould et al.[SIAM J.Optim.,2005]is extended to solve constrained optimization problems.In our proposed algorithm,the constraints are partitioned into several parts,and the entry of our filter consists of these different parts.Not only the criteria for accepting a trial step would be relaxed,but the individual behavior of each part of constraints is considered.One feature is that the undesirable link between the objective function and the constraint violation in the filter acceptance criteria disappears.The other is that feasibility restoration phases are unnecessary because a consistent quadratic programming subproblem is used.We prove that our algorithm is globally convergent to KKT points under the constant positive generators(CPG)condition which is weaker than the well-known Mangasarian-Fromovitz constraint qualification(MFCQ)and the constant positive linear dependence(CPLD).Numerical results are presented to show the efficiency of the algorithm.
基金This work is supported by the Ph.D.Scientific Research Foun-dation of Taiyuan University of Science and Technology(Nos.20182020,20182058)the National Natural Science Foundation of China(No.21978212)+2 种基金the Science and Technology Plans of Tian-jin(No.18PTSYJC00180)the Scientific and Technological Innova-tion Project of University in Shanxi Province(Nos.2019L0657,2019L0628)the Doctoral Award Fund of Shanxi Province(No.20192045).
文摘Herein,a novel sensor(TPE-UiO-66)was designed via anchoring monodentate tetraphenylethylene(TPE)onto UiO-66 framework.The combination of the distinct aggregation-induced emission(AIE)of TPE and the easy replacement of monodentate linker by guest phosphate,makes TPE-UiO-66 an ideal pltform for sensing HPO_(4)^(2-)。Experimental results indicate that TPE-UiO-66 can selectively sense HPO_(4)^(2-)from other common anions.
