Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified ...Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW.展开更多
A first-principles study was reported based on density functional theory of hydrogen vacancy,metal dopants,metal dopant-vacancy complex in LiBH4,a promising material for hydrogen storage.The formation of H vacancy and...A first-principles study was reported based on density functional theory of hydrogen vacancy,metal dopants,metal dopant-vacancy complex in LiBH4,a promising material for hydrogen storage.The formation of H vacancy and metal doping in LiBH4 is difficult,and their concentrations are low.The presence of one kind of defect is helpful to the formation of other kind of defect.Based on the analysis of electronic structure,the improvement of the dehydrogenating kinetics of LiBH4 by metal catalysts is due to the weaker bonding of B—H and the new metal-like system,which makes H atom diffuse easily;H vacancy accounts for a trace amount of BH3 release during the decomposing process of LiBH4;metal dopant weakens the strength of B—H bonds,which reduces the dehydriding temperature of LiBH4.The roles of metal and vacancy in the metal dopant-vacancy complex can be added in LiBH4 system.展开更多
The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as S...The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as SnO2 and SnO2/ZnO bi-layer films were exposed to atomic H at various substrate temperatures and for various treatment times. A decrease in the transmittance due to reduction by atomic H was scarcely observed for SnO2 / ZnO bi-layer,while a decrease for SnO2 was found to depend strongly on the substrate temperature. The resistivity of SnO2 films decreases significantly when substrate temperature exceeds 150℃in H-plasma. However, H-plasma treatment has little impact on the resistivity of SnO2/ZnO bi-layer film. The reason for the decrease in the transmittance is the appearance of metallic Sn on the surface, and under this condition no μc-Si： H film is deposited. SnO2/ZnO bi-layer is very effective for the suppression of the reduction of TCO during μc-Si：H deposition. The performance of microcrystalline silicon solar cells fabricated on ZnO/SnO2/glass is also investigated.展开更多
A new solid acid was prepared by trifluoromethanesulfonic acid （TFMSA） impregnation into an acid‐treated attapulgite （ATA）. Di（1‐naphthyl）methane （DNM） hydrocracking was used as the probe reaction to evaluat...A new solid acid was prepared by trifluoromethanesulfonic acid （TFMSA） impregnation into an acid‐treated attapulgite （ATA）. Di（1‐naphthyl）methane （DNM） hydrocracking was used as the probe reaction to evaluate the catalytic performance of TFMSA/ATA for cleaving Car–Calk bridged bonds in coals. The results show that DNM was specifically hydrocracked to naphthalene and 1‐methylnaphthalene over TFMSA/ATA in methanol in the absence of gaseous hydrogen. In partic‐ular, TFMSA/ATA was demonstrated to be stable after four cycles with slight loss in catalytic activi‐ty. Furthermore, a proposed H＋transfer mechanism successfully interprets the TFMSA/ATA‐cata‐lyzed hydrocracking reaction of DNM.展开更多
文摘Propane dehydrogenation(PDH)on Ga/H-ZSM-5 catalysts is a promising reaction for propylene production,while the detail mechanism remains debatable.Ga_(2)O_(2)^(2+) stabilized by framework Al pairs have been identified as the most active species in Ga/H-ZSM-5 for PDH in our recent work.Here we demonstrate a strong correlation between the PDH activity and a fraction of Ga_(2)O_(2)^(2+) species corresponding to the infrared GaH band of higher wavenumber(GaHHW)in reduced Ga/H-ZSM-5,instead of the overall Ga_(2)O_(2)^(2+) species,by employing five H-ZSM-5 supports sourced differently with comparable Si/Al ratio.This disparity in Ga_(2)O_(2)^(2+) species stems from their differing capacity in completing the catalytic cycle.Spectroscopic results suggest that PDH proceeds via a two-step mechanism:(1)C-H bond activation of propane on H-Ga_(2)O_(2)^(2+) species(rate determining step);(2)β-hydride elimination of adsorbed propyl group,which only occurs on active Ga_(2)O_(2)^(2+) species corresponding to GaHHW.
基金2013年国家级大学生创新创业训练计划项目(201313256001)湖北师范学院硕士研究生创新科研基金项目(1051320130216)+1 种基金National Undergraduate Training Programs for Innovation and Entrepreneurship(201313256001)Postgraduate Innovation Scientific Research Foundation of Hubei Normal University(1051320130216)
基金Project (2009AA05Z105) supported by the High-tech Research and Development Program of ChinaProject (20102173) supported by the Natural Science Foundation of Liaoning Province,China
文摘A first-principles study was reported based on density functional theory of hydrogen vacancy,metal dopants,metal dopant-vacancy complex in LiBH4,a promising material for hydrogen storage.The formation of H vacancy and metal doping in LiBH4 is difficult,and their concentrations are low.The presence of one kind of defect is helpful to the formation of other kind of defect.Based on the analysis of electronic structure,the improvement of the dehydrogenating kinetics of LiBH4 by metal catalysts is due to the weaker bonding of B—H and the new metal-like system,which makes H atom diffuse easily;H vacancy accounts for a trace amount of BH3 release during the decomposing process of LiBH4;metal dopant weakens the strength of B—H bonds,which reduces the dehydriding temperature of LiBH4.The roles of metal and vacancy in the metal dopant-vacancy complex can be added in LiBH4 system.
文摘The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as SnO2 and SnO2/ZnO bi-layer films were exposed to atomic H at various substrate temperatures and for various treatment times. A decrease in the transmittance due to reduction by atomic H was scarcely observed for SnO2 / ZnO bi-layer,while a decrease for SnO2 was found to depend strongly on the substrate temperature. The resistivity of SnO2 films decreases significantly when substrate temperature exceeds 150℃in H-plasma. However, H-plasma treatment has little impact on the resistivity of SnO2/ZnO bi-layer film. The reason for the decrease in the transmittance is the appearance of metallic Sn on the surface, and under this condition no μc-Si： H film is deposited. SnO2/ZnO bi-layer is very effective for the suppression of the reduction of TCO during μc-Si：H deposition. The performance of microcrystalline silicon solar cells fabricated on ZnO/SnO2/glass is also investigated.
基金supported by the Fundamental Research Fund for the Central Universities (China University of Mining & Technology,2014ZDPY34)the Priority Academic Program Development of Jiangsu Higher Education Institutions~~
文摘A new solid acid was prepared by trifluoromethanesulfonic acid （TFMSA） impregnation into an acid‐treated attapulgite （ATA）. Di（1‐naphthyl）methane （DNM） hydrocracking was used as the probe reaction to evaluate the catalytic performance of TFMSA/ATA for cleaving Car–Calk bridged bonds in coals. The results show that DNM was specifically hydrocracked to naphthalene and 1‐methylnaphthalene over TFMSA/ATA in methanol in the absence of gaseous hydrogen. In partic‐ular, TFMSA/ATA was demonstrated to be stable after four cycles with slight loss in catalytic activi‐ty. Furthermore, a proposed H＋transfer mechanism successfully interprets the TFMSA/ATA‐cata‐lyzed hydrocracking reaction of DNM.
