ITR zeolite could be potentially used as catalysts in methanol to propylene(MTP),where their performance is strongly related to its Al distribution.However,the control of Al distribution in ITR zeolite poses a signifi...ITR zeolite could be potentially used as catalysts in methanol to propylene(MTP),where their performance is strongly related to its Al distribution.However,the control of Al distribution in ITR zeolite poses a significant synthetic challenge.Herein,we demonstrate the possibility to control the Al distribution in ITR zeolites using zeolite A as an aluminum source(A-ITR).The A-ITR exhibited similar crystallinity,nanosheet morphology,textual parameters,and acidic concentration with those of conventional ITR made zeolites using aluminum isopropoxide as an aluminum source(C-ITR).Characterizations of the zeolite product with^(27)Al MQ.MAS NMR spectra,^(27)Al MAS NMR spectra,and 1-hexene cracking reveal that the A-ITR zeolites have more Al species distributed in T6 and T8 sites located in relatively smaller micropores of the framework than C-ITR.As a result,the A-ITR gave enhanced catalyst lifetime and propylene selectivity due to the suppression of the aromatic cycle in the MTP reaction,compared with the C-ITR.This work provides an alternative approach to prepare efficient ITR zeolites for MTP reaction.展开更多
Resonance lines are extensively used to diagnose electronic temperature Te and ions distribution. However, the analysis of the x-ray spectroscopy emitted from plasmas produced by a ns laser Jsually needs the help of a...Resonance lines are extensively used to diagnose electronic temperature Te and ions distribution. However, the analysis of the x-ray spectroscopy emitted from plasmas produced by a ns laser Jsually needs the help of a code or some assumptions. In this paper, a diagnostic idea of using line-pairs emitted from a doubly-excited state is proposed. By using the method presented in this paper, Te and the fractional population ratio of bare nuclei and H-like ions are directly obtained from the emission intensity ratios.展开更多
The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS）...The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.展开更多
A novel membrane distillation concentration method was used m prepare high concentration polyaluminum chloride （PAC1） with high content of AID or Ale. 2.52 mol/L PACl1 with 88% Alb and 2.38 mol/L PACl2 with 61% Ale ...A novel membrane distillation concentration method was used m prepare high concentration polyaluminum chloride （PAC1） with high content of AID or Ale. 2.52 mol/L PACl1 with 88% Alb and 2.38 mol/L PACl2 with 61% Ale were successfully prepared. Three coagulants, AlCl3, PACl1 and PACl2 were investigated on their hydrolysis behavior and speciation under different conditions. The effects of pH and dilution ratio on Al species distribution were investigated by ferron assay. Experimental result showed that pH had a significant effect on Al species distribution for the three coagulants. Dilution ratio had little effects on Alb and Alc distribution in whole dilution process except the beginning for PACl1 and PACl2. The results indicated that transformation of Al depends largely on their original composition. AlCl3 was the most unstable coagulant among these three coagulants during hydrolysis process. PACl1 and PACl2 with significant amounts of highly charged and stable polynuclear aluminum hydrolysis products were less affected by the hydrolysis conditions and could maintain high speciation stability under various conditions.展开更多
Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of pro...Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin(MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large Me OH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by 27 Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.展开更多
基金supported by the National Key Research and Development Program of China(2022YFA1503602)the National Natural Science Foundation of China(22288101,U21B20101 and 22172141)+1 种基金the BASF International Network of Centers of Excellence projectthe Zhejiang Provincial Natural Science Foundation of China(LR24B030001)。
文摘ITR zeolite could be potentially used as catalysts in methanol to propylene(MTP),where their performance is strongly related to its Al distribution.However,the control of Al distribution in ITR zeolite poses a significant synthetic challenge.Herein,we demonstrate the possibility to control the Al distribution in ITR zeolites using zeolite A as an aluminum source(A-ITR).The A-ITR exhibited similar crystallinity,nanosheet morphology,textual parameters,and acidic concentration with those of conventional ITR made zeolites using aluminum isopropoxide as an aluminum source(C-ITR).Characterizations of the zeolite product with^(27)Al MQ.MAS NMR spectra,^(27)Al MAS NMR spectra,and 1-hexene cracking reveal that the A-ITR zeolites have more Al species distributed in T6 and T8 sites located in relatively smaller micropores of the framework than C-ITR.As a result,the A-ITR gave enhanced catalyst lifetime and propylene selectivity due to the suppression of the aromatic cycle in the MTP reaction,compared with the C-ITR.This work provides an alternative approach to prepare efficient ITR zeolites for MTP reaction.
文摘Resonance lines are extensively used to diagnose electronic temperature Te and ions distribution. However, the analysis of the x-ray spectroscopy emitted from plasmas produced by a ns laser Jsually needs the help of a code or some assumptions. In this paper, a diagnostic idea of using line-pairs emitted from a doubly-excited state is proposed. By using the method presented in this paper, Te and the fractional population ratio of bare nuclei and H-like ions are directly obtained from the emission intensity ratios.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51337002,51077028,51502063 and 51307046the Foundation of Harbin Science and Technology Bureau of Heilongjiang Province under Grant No RC2014QN017034
文摘The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.
基金supported by the National Natural Science Foundation of China (No 50708109, 20577061,40673003)the National Hi-Tech Research and Develop-ment Key Program (863) of China (No 2007AA06Z339)the Special Fund from the State Key Laboratory of Environmental Aquatic Chemistry (No 09Y02ESPCR,09Z01ESPCR)
文摘A novel membrane distillation concentration method was used m prepare high concentration polyaluminum chloride （PAC1） with high content of AID or Ale. 2.52 mol/L PACl1 with 88% Alb and 2.38 mol/L PACl2 with 61% Ale were successfully prepared. Three coagulants, AlCl3, PACl1 and PACl2 were investigated on their hydrolysis behavior and speciation under different conditions. The effects of pH and dilution ratio on Al species distribution were investigated by ferron assay. Experimental result showed that pH had a significant effect on Al species distribution for the three coagulants. Dilution ratio had little effects on Alb and Alc distribution in whole dilution process except the beginning for PACl1 and PACl2. The results indicated that transformation of Al depends largely on their original composition. AlCl3 was the most unstable coagulant among these three coagulants during hydrolysis process. PACl1 and PACl2 with significant amounts of highly charged and stable polynuclear aluminum hydrolysis products were less affected by the hydrolysis conditions and could maintain high speciation stability under various conditions.
基金supported by the BASF and the Advanced Research Center Chemical Building Blocks Consortium (ARC CBBC) for Funding under Project (2016.007.TUD)
文摘Identification of the catalyst characteristics correlating with the key performance parameters including selectivity and stability is key to the rational catalyst design. Herein we focused on the identification of property-performance relationships in the methanol-to-olefin(MTO) process by studying in detail the catalytic behaviour of MFI, MEL and their respective intergrowth zeolites. The detailed material characterization reveals that both the high production of propylene and butylenes and the large Me OH conversion capacity correlate with the enrichment of lattice Al sites in the channels of the pentasil structure as identified by 27 Al MAS NMR and 3-methylpentane cracking results. The lack of correlation between MTO performance and other catalyst characteristics, such as crystal size, presence of external Brønsted acid sites and Al pairing suggests their less pronounced role in defining the propylene selectivity. Our analysis reveals that catalyst deactivation is rather complex and is strongly affected by the enrichment of lattice Al in the intersections, the overall Al-content, and crystal size. The intergrowth of MFI and MEL phases accelerates the catalyst deactivation rate.
