According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^...According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^(4+) and Cr^(5+) coordinated with distorted octahedra. The reason of fading of β-C_2S hydrate is that the strength of light absorption declines be- cause of the valence change of chromium ions and chroninm dissolves out and loses in water.展开更多
Simultaneous ethane and acetylene removal from a C_(2)-gases mixture(C_(2)H_(6),C_(2)H_(4),and C_(2)H_(2))through a one-step separation process for ethylene purification is of great importance yet challenging in petro...Simultaneous ethane and acetylene removal from a C_(2)-gases mixture(C_(2)H_(6),C_(2)H_(4),and C_(2)H_(2))through a one-step separation process for ethylene purification is of great importance yet challenging in petrochemical industry,owing to their similar molecule sizes and physical properties.Herein,a series of multifunctionalized metal–organic frameworks(MOFs),LIFM-XYY-1∼8(LIFM stands for Lehn Institute of Functional Materials,and XYY are the initials of the first author),are constructed via a dynamic spacer installation(DSI)approach to optimize the pore-nanospaces for efficient C_(2)H_(4) isolation from the ternary C_(2)-gases mixture.Installation of variable organic-spacers into the prototypical MOFs,LIFM-28 or PCN-700,results in dramatically improved pore volume/surface area,contracted pore size,and functionalized pore surface,which in turn bring out high C_(2)-gases uptake capacities,enhanced C_(2)H_(6) and C_(2)H_(2) adsorption selectivities over C_(2)H_(4),and fast adsorption kinetics,providing an effective strategy to achieve delicate trade-off among these indexes for adequate separation performance.Specifically,optimized LIFM-XYY-7 presents four-times C_(2)H_(6) and C_(2)H_(2) adsorption capacities than proto-PCN-700.Dynamic breakthrough experiments reveal that poly-grade C_(2)H_(4)(>99.9%)can be obtained from binary or ternary C_(2)-hydrocarbon mixtures through a single separation process.Combined with themolecular simulations,this work demonstrates a promising protocol of porenanospace engineering via multi-functional optimization by the DSI approach to screen out MOFs for a formidable task.展开更多
文摘According to the theory of crystal field, the existing state of chromium ions in β-C_2S was studied with optical spectra and EPR. The energy levels of chromium ions were calculated. Chromium ions exist in form of Cr^(4+) and Cr^(5+) coordinated with distorted octahedra. The reason of fading of β-C_2S hydrate is that the strength of light absorption declines be- cause of the valence change of chromium ions and chroninm dissolves out and loses in water.
基金supported by the NKRD Program of China(grant no.2021YFA1500401)NSFC Projects(grant nos.21890380,21821003,22001271,22090061,and 21801252)+1 种基金the LIRT Project of Guangdong PRTP(grant no.2017BT01C161)FRF for the Central Universities(grant no.20lgpy79).
文摘Simultaneous ethane and acetylene removal from a C_(2)-gases mixture(C_(2)H_(6),C_(2)H_(4),and C_(2)H_(2))through a one-step separation process for ethylene purification is of great importance yet challenging in petrochemical industry,owing to their similar molecule sizes and physical properties.Herein,a series of multifunctionalized metal–organic frameworks(MOFs),LIFM-XYY-1∼8(LIFM stands for Lehn Institute of Functional Materials,and XYY are the initials of the first author),are constructed via a dynamic spacer installation(DSI)approach to optimize the pore-nanospaces for efficient C_(2)H_(4) isolation from the ternary C_(2)-gases mixture.Installation of variable organic-spacers into the prototypical MOFs,LIFM-28 or PCN-700,results in dramatically improved pore volume/surface area,contracted pore size,and functionalized pore surface,which in turn bring out high C_(2)-gases uptake capacities,enhanced C_(2)H_(6) and C_(2)H_(2) adsorption selectivities over C_(2)H_(4),and fast adsorption kinetics,providing an effective strategy to achieve delicate trade-off among these indexes for adequate separation performance.Specifically,optimized LIFM-XYY-7 presents four-times C_(2)H_(6) and C_(2)H_(2) adsorption capacities than proto-PCN-700.Dynamic breakthrough experiments reveal that poly-grade C_(2)H_(4)(>99.9%)can be obtained from binary or ternary C_(2)-hydrocarbon mixtures through a single separation process.Combined with themolecular simulations,this work demonstrates a promising protocol of porenanospace engineering via multi-functional optimization by the DSI approach to screen out MOFs for a formidable task.
