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Effects of ancillary ligands in acceptorless benzyl alcohol dehydrogenation mediated by phosphine-free cobalt complexes

Frontiers of Chemical Science and Engineering 2023, Volume 17, Issue 3,   Pages 314-325 doi: 10.1007/s11705-022-2219-2

Abstract: Acceptorless alcohol dehydrogenation stands out as one of the most promising strategies in hydrogen storage technologies. Among various catalytic systems for this reaction, cost-effective molecular catalysts using phosphine-free ligands have gained considerable attention. However, the central challenge for using non-precious metals is to overcome the propensity of reacting by one-electron pathway. Herein, we synthesized a phosphine-free η5-C5Me5-Co complex by using the metal–ligand cooperative strategy and compared its activity with analogous catalysts toward acceptorless alcohol dehydrogenation. The catalyst showed excellent performance with a turnover number of 130.4 and a selectivity close to 100%. The improved performance among the class of η5-C5Me5-Co complexes could be attributed to the more accessible Co center and its cooperation with the redox-active ligand. To further study the systematic structure-activity relationship, we investigated the electronic structures of η5-C5Me5-Co complexes by a set of characterizations. The results showed that the redox-active ligand has a significant influence on the η5-C5Me5-Co moiety. In the meantime, the proximal O−/OH group is beneficial for shuttling protons. For the catalytic cycle, two dehydrogenation scenarios were interrogated through density functional theory, and the result suggested that the outer-sphere pathway was preferred. The formation of a dihydrogen complex was the rate-determining step with a ΔG value of 16.9 kcal∙mol‒1. The electron population demonstrated that the η5-C5Me5 ligand played a key role in stabilizing transition states during dehydrogenation steps. This work identified the roles of vital ligand components to boost catalytic performance and offered rationales for designing metal–ligand cooperative nonprecious metal complexes.

Keywords： acceptorless alcohol dehydrogenation     η5-C5Me5-Co     metal–ligand cooperation     theoreticalcalculation    

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A review on different theoretical models of electrocaloric effect for refrigeration

Frontiers in Energy 2023, Volume 17, Issue 4,   Pages 478-503 doi: 10.1007/s11708-023-0884-6

Abstract: This paper reviews the electrocaloric effect of ferroelectric materials based on different theoreticalFirst, it provides four different calculation scales (the first-principle-based effective Hamiltonian

Keywords： electrocaloric effect     effective Hamiltonian     phase-field modeling     different theoretical models    

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Explicit finite element method for calculation and analysis to the elasto-plastic dynamic response of

LI Liang, DU Xiuli, LI Liyun, ZHAO Chenggang

Frontiers of Structural and Civil Engineering 2007, Volume 1, Issue 4,   Pages 436-442 doi: 10.1007/s11709-007-0059-2

Abstract: the integral formula mentioned above, the time-domain explicit finite element method is developed for calculation

Keywords： discretization     computational     calculation     integral     requirement    

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Theoretical analysis and calculation for filling factor of solar cellvarying along with illumination

Ding Jinlei,ChengXiaofang,Zhai Zaiteng,Zha Jun,Mao Meiqin

Strategic Study of CAE 2007, Volume 9, Issue 6,   Pages 82-87

Abstract:

Based on the solar cell DC model and the mathematic expression of maximum power point,  the equations describing short circuit current,  open circuit voltage,  maximum power current,  voltage and filling factor varying along with the illumination intensity are deduced and calculated with two real solar cells data. The fact that short circuit current and maximum power current are proportional to the illumination intensity, and open circuit voltage and maximum power voltage are proportional to the natural logarithm of illumination intensity is certified. The relation of filling factor varying along with the illumination intensity is not a simple functional expression and effected by the solar cell model parameters is present. A simulated experiment is established to valid the theoretic analysis and calculating by Multisim.

Keywords： solar cell     illumination intensity     output characteristics     filling factor    

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NOx removal by non-thermal plasma reduction: experimental and theoretical investigations

Frontiers of Chemical Science and Engineering 2022, Volume 16, Issue 10,   Pages 1476-1484 doi: 10.1007/s11705-022-2165-z

Abstract: This work presents the experimental and theoretical study on the Keywords： ${\rm{NO}}_x $ removal     NTP reduction     mechanism     energy consumption    

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Application of an efficient stochastic calculation method on the seismic analysis of an isolated structure

Wei GUO, Zhiwu YU

Frontiers of Structural and Civil Engineering 2012, Volume 6, Issue 4,   Pages 379-384 doi: 10.1007/s11709-012-0180-8

Abstract: However, traditional seismic calculation theory and methods are derived based on the assumption thatBased on this drawback, a new, more efficient stochastic calculation method, an improvement on the pseudo-excitationMoreover, the calculation process of the seismic response of an isolated structure is convergent.

Keywords： isolated structure     stochastic response     non-proportional damping     efficient     accurate     pseudo-excitation method    

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Thermal transport properties of monolayer phosphorene: a mini-review of theoretical studies

Guangzhao QIN, Ming HU

Frontiers in Energy 2018, Volume 12, Issue 1,   Pages 87-96 doi: 10.1007/s11708-018-0513-y

Abstract: Phosphorene, a two-dimensional (2D) elemental semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D materials. Its rapidly growing applications in nano-/opto-electronics and thermoelectrics call for fundamental understanding of the thermal transport properties. Considering the fact that there have been so many studies on the thermal transport in phosphorene, it is on emerging demand to have a review on the progress of previous studies and give an outlook on future work. In this mini-review, the unique thermal transport properties of phosphorene induced by the hinge-like structure are examined. There exists a huge deviation in the reported thermal conductivity of phosphorene in literature. Besides, the mechanism underlying the deviation is discussed by reviewing the effect of different functionals and cutoff distance in calculating the thermal transport properties of phosphorene. It is found that the (vdW) interactions play a key role in the formation of resonant bonding, which leads to long-ranged interactions. Taking into account of the vdW interactions and including the long-ranged interactions caused by the resonant bonding with large cutoff distance are important for getting the accurate and converged thermal conductivity of phosphorene. Moreover, a fundamental insight into the thermal transport is provided based on the review of resonant bonding in phosphorene. This mini-review summarizes the progress of the thermal transport in phosphorene and gives an outlook on future horizons, which would benefit the design of phosphorene based nano-electronics.

Keywords： thermal transport     phosphorene     resonant bonding    

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Prediction of the theoretical and semi-empirical model of ambient temperature

Foued CHABANE,Noureddine MOUMMI,Abdelhafid BRIMA,Abdelhafid MOUMMI

Frontiers in Energy 2016, Volume 10, Issue 3,   Pages 268-276 doi: 10.1007/s11708-016-0413-y

Abstract: It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowledge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during measurement. The ambient temperature over time is modeled based on the previous and data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.

Keywords： ambient temperature     environment     correlation     theoretical model     semi-empirical    

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The calculation of equivalence factor for ecological footprints in China: a methodological note

Moucheng LIU,Wenhua LI,Dan ZAHNG,Ning SU

Frontiers of Environmental Science & Engineering 2015, Volume 9, Issue 6,   Pages 1015-1024 doi: 10.1007/s11783-014-0670-0

Abstract: The Ecological Footprint (EF), a physical indicator to measure the extent of humanity’s use of natural resources, has gained much attention since it was first used by Wackernagel and Rees in 1996. In order to appraise land area types with different levels of productivity, they introduced the concept of an equivalence factor. This relates to the average primary biomass productivities of different types of land (i.e. arable land, pasture, forest, water/fishery, built-up land and fossil energy land) to the regional average primary biomass productivity of all land types in a given year. Hence, the equivalence factor is an important parameter in the EF model and it directly affects the reliability of all results. Thus, this article calculates equivalence factors on the national and provincial levels in China based on Net Primary Production (NPP) from MODIS 1 km data in 2008. Firstly, based on the Light Utility Efficiency and CASA model, the NPP of different biologically productive lands of China and of different provinces was calculated. Secondly, China’s equivalence factor for 6 land area types was calculated based on NPP: arable land and built-up land has an equivalence factor of 1.71, forest and fossil energy land has a factor of 1.41, pasture has a factor of 0.44 and water/fishery 0.35; Finally, the equivalence factor of 6 land area types in different provinces was also calculated. The NPP of each ecosystem type varies along with the equivalence factor in different provinces. However, the ranking of the equivalence factors in different provinces remain the same, with that of arable land being the largest, and the water/fishery being the smallest.

Keywords： ecological footprint     equivalence factor     net primary production     biological capacity     land types    

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Theoretical and technological exploration of deep

Heping XIE, Yang JU, Shihua REN, Feng GAO, Jianzhong LIU, Yan ZHU

Frontiers in Energy 2019, Volume 13, Issue 4,   Pages 603-611 doi: 10.1007/s11708-019-0643-x

Abstract: To effectively acquire coal resources deeper than 2000 m, new theoretical and technological conceptsThen, it presents a new theoretical concept, including the theories of mining-induced rock mechanics,In summary, this paper develops new theoretical and technological systems for accomplishing groundbreaking

Keywords： coal resource     deep in situ     fluidized mining     theoretical system     key technologies     strategic roadmap    

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Unified calculation method and its application in determining the uniaxial mechanical properties of concrete

Faxing DING, Xiaoyong YING, Linchao ZHOU, Zhiwu YU

Frontiers of Structural and Civil Engineering 2011, Volume 5, Issue 3,   Pages 381-393 doi: 10.1007/s11709-011-0118-6

Abstract: This paper presents a unified calculation method and its application in determining the uniaxial mechanicalhigh-strength and super high-strength concrete in China and performing a regression analysis, unified calculation

Keywords： concrete     mechanical properties     stress-strain relationship     uniaxial stress     application    

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Theoretical analysis and experimental investigation of valveless piezoelectric pump with unsymmetrical

ZHANG Jianhui, LU Jizhuang, XIA Qixiao, LI Hong

Frontiers of Mechanical Engineering 2007, Volume 2, Issue 1,   Pages 13-19 doi: 10.1007/s11465-007-0002-1

Abstract: Meanwhile, the theoretical equation of the pump flow rate is established.It is proved that the theory is rational and correct by comparing the experimental flow rate and the theoreticalIn addition, for calculating the theoretical flow rate, the positive and converse flow resistance coefficients

Keywords： unsymmetrical     theoretical flow     theoretical equation     pump flow     converse flow    

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Mechanism insight into the formation of HS from thiophene pyrolysis: A theoretical study

Frontiers of Environmental Science & Engineering 2021, Volume 15, Issue 6, doi: 10.1007/s11783-021-1404-8

Abstract:

• Possible formation pathways of H2S were revealed in thiophene pyrolysis.

Keywords： Density functional theory     Waste rubber     Thiophene     H2S     Pyrolysis    

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enhancement in high acidity using di-(2-ethylhexyl)phosphoric acid with [Cl] present: an experimental and theoretical

Frontiers of Chemical Science and Engineering 2023, Volume 17, Issue 1,   Pages 56-67 doi: 10.1007/s11705-022-2185-8

Abstract: Separation of vanadium from black shale leaching solution at low pH is very meaningful, which can effectively avoid the generation of alkali neutralization slag and the resulting vanadium loss. In this study, coordination mechanism of vanadium in acid leaching solution at low pH was investigated with the intervention of chloride ions. Under the conditions of pH 0.8, di-(2-ethylhexyl)phosphoric acid concentration of 20%, phase ratio of 1:2, and extraction time of 8 min, the vanadium extraction could reach 80.00%. The Fourier transform infrared and electrospray ionization results reveal that, despite the fact that the chloride ion in the leachate could significantly promote vanadium extraction, the chloride ion does not enter the organic phase, indicating an intriguing phenomenon. Among Cl−–V, SO42−–V, and H2O–V, the V–Cl bond is longer and the potential difference between coordinate ions and vanadium is smaller. Therefore, VO2+ gets easily desorbed with chloride ions and enter the organic phase. At the same time, the hydrogen ions of di-(2-ethylhexyl)phosphoric acid also enter the water phase more easily, which reduces the pH required for the extraction reaction.

Keywords： vanadium     black shale     solvent extraction     high acidity extraction    

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Governance approach to China’s environmental challenges: Towards a theoretical synthesis

QI Ye, XUE Lan, ZHANG Lingyun

Frontiers of Environmental Science & Engineering 2007, Volume 1, Issue 4,   Pages 385-400 doi: 10.1007/s11783-007-0066-5

Abstract: This paper reviewed recent research in environmental governance as a response to environmental challenges at various spatial, temporal and administrative scales. It documented the shift of approach from regulation to governance, and attempted to provide a comprehensive understanding why and how the transformation occurred. It also described major factors and forces of environmental governance, and discussed research advance in environmental governance theory. Finally, this paper summarized recent research findings on environmental governance in China, and listed policy recommendation for enhancing the governance.

Keywords： environmental governance     approach     temporal     regulation     various    

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Title Author Date Type Operation

Effects of ancillary ligands in acceptorless benzyl alcohol dehydrogenation mediated by phosphine-free cobalt complexes

Journal Article

A review on different theoretical models of electrocaloric effect for refrigeration

Journal Article

Explicit finite element method for calculation and analysis to the elasto-plastic dynamic response of

LI Liang, DU Xiuli, LI Liyun, ZHAO Chenggang

Journal Article

Theoretical analysis and calculation for filling factor of solar cellvarying along with illumination

Ding Jinlei,ChengXiaofang,Zhai Zaiteng,Zha Jun,Mao Meiqin

Journal Article

NOx removal by non-thermal plasma reduction: experimental and theoretical investigations

Journal Article

Application of an efficient stochastic calculation method on the seismic analysis of an isolated structure

Wei GUO, Zhiwu YU

Journal Article

Thermal transport properties of monolayer phosphorene: a mini-review of theoretical studies

Guangzhao QIN, Ming HU

Journal Article

Prediction of the theoretical and semi-empirical model of ambient temperature

Foued CHABANE,Noureddine MOUMMI,Abdelhafid BRIMA,Abdelhafid MOUMMI

Journal Article

The calculation of equivalence factor for ecological footprints in China: a methodological note

Moucheng LIU,Wenhua LI,Dan ZAHNG,Ning SU

Journal Article

Theoretical and technological exploration of deep

Heping XIE, Yang JU, Shihua REN, Feng GAO, Jianzhong LIU, Yan ZHU

Journal Article

Unified calculation method and its application in determining the uniaxial mechanical properties of concrete

Faxing DING, Xiaoyong YING, Linchao ZHOU, Zhiwu YU

Journal Article

Theoretical analysis and experimental investigation of valveless piezoelectric pump with unsymmetrical

ZHANG Jianhui, LU Jizhuang, XIA Qixiao, LI Hong

Journal Article

Mechanism insight into the formation of HS from thiophene pyrolysis: A theoretical study

Journal Article

enhancement in high acidity using di-(2-ethylhexyl)phosphoric acid with [Cl] present: an experimental and theoretical

Journal Article

Governance approach to China’s environmental challenges: Towards a theoretical synthesis

QI Ye, XUE Lan, ZHANG Lingyun

Journal Article