A facile and user friendly technique to immobilize the late-transition metal complexes on spherical MgCl2/SiO2/THF support has been developed. The spherical MgCl2/SiO2/THF-supported late-transition metal catalysts 2,6...A facile and user friendly technique to immobilize the late-transition metal complexes on spherical MgCl2/SiO2/THF support has been developed. The spherical MgCl2/SiO2/THF-supported late-transition metal catalysts 2,6-bis-[1-(2,6-dimethylphenylimino)ethyl]pyridine iron(II) dichloride(SC-A) and 1,4-bis(2,6-dimethylphenyl)- acenaphthene diimine nickel(II) dibromide(SC-B) for ethylene polymerization has been prepared by spray-drying technique using tetrahydrofuran suspension containing MgCl2, SiO2 and late-transition metal complexes. The catalysts were characterized by BET, XRD, SEM and the polymers were analyzed using GPC, DSC and 13C-NMR. The test results show that spray-drying is a very effective method for immobilizing late-transition metal catalysts for ethylene polymerization. Among six kinds of cocatalysts for olefin polymerization, TMA and TEA were confirmed to be more effective than other compounds for the ethylene polymerization system using the catalyst SC-A. For the case of the catalyst SC-B, DEAC showed the best performance as cocatalysts in ethylene polymerization. The replication of the catalyst morphology was found in the resultant polyethylene.展开更多
In situ FT-IR of SiO2-supported (pph3)Hpt(μ-pph2)(μ-CO)Mo(co)4heterobinuclear hydrido carbonyl catalyst in the CO hydrogenation condition has been investigated.
The SiO2-Supported (PPh3)2HPt(μ-CO) (μ-PPh2)M(CO) 4 (M-Cr.Mo, W) complel catalysts catalyzing CO2 hydrogenation are reported.The catalysts exhibited high catalytic activity and selectivity toward oxygenates
The inherent irreducibility and limited sulfur dioxide tolerance of zeolites constrain oxygen exchange efficiency in palladium/zeolite catalysts,which can adversely affect their performance in methane combustion.Herei...The inherent irreducibility and limited sulfur dioxide tolerance of zeolites constrain oxygen exchange efficiency in palladium/zeolite catalysts,which can adversely affect their performance in methane combustion.Herein,a novel molecular sieve(Silicate-1,denoted as S-1)catalyst functionalized with rare earth oxide sites was developed for catalytic methane combustion.Although both Pd/S-1@CeO2-30(in which CeO2content was 30 wt.%)and Pd/S-1 catalysts demonstrated comparable initial catalytic activities,the Pd/S-1@CeO2-30 sample achieved a methane reaction rate of 114.0μmol/(gPd·s)and the highest TOFPd(0.033s-1),with a 90%methane conversion at 424℃ at a space velocity of 20,000 mL/(g h).The CeO2shell in Pd/S-1@CeO2-30 exhibited the superior longterm stability that was attributed to the redox property of CeO2,which could facilitate the provision of abundant oxygen species.As a result,the Pd/S-1@CeO2-30 catalyst maintained stable performance in 10,000-ppm CH4methane combustion at 400℃ and retained a high CH4conversion efficiency even under exposure to 50 ppm SO2.Similarly,Ce0.6Zr0.4O2or Sm2O3shell also demonstrated comparable SO2resistance.Detailed characterization results revealed that CeO2acted as an exceptional redox center,significantly enhanced SO2adsorption,and effectively inhibited the poisoning of the active PdO sites by SO2,leading to a notable improvement in sulfur dioxide tolerance.These findings highlighted the critical role of the core-shell structure in enhancing catalyst resistance to SO2poisoning during methane combustion.The present work provides valuable insights into the appropriate designing of advanced core-shell catalysts with improved durability and performance in the sulfur dioxide-containing environments.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.U1162114)the Science Foundation of Tianjin University of Science & Technology (20090420)
摘要A facile and user friendly technique to immobilize the late-transition metal complexes on spherical MgCl2/SiO2/THF support has been developed. The spherical MgCl2/SiO2/THF-supported late-transition metal catalysts 2,6-bis-[1-(2,6-dimethylphenylimino)ethyl]pyridine iron(II) dichloride(SC-A) and 1,4-bis(2,6-dimethylphenyl)- acenaphthene diimine nickel(II) dibromide(SC-B) for ethylene polymerization has been prepared by spray-drying technique using tetrahydrofuran suspension containing MgCl2, SiO2 and late-transition metal complexes. The catalysts were characterized by BET, XRD, SEM and the polymers were analyzed using GPC, DSC and 13C-NMR. The test results show that spray-drying is a very effective method for immobilizing late-transition metal catalysts for ethylene polymerization. Among six kinds of cocatalysts for olefin polymerization, TMA and TEA were confirmed to be more effective than other compounds for the ethylene polymerization system using the catalyst SC-A. For the case of the catalyst SC-B, DEAC showed the best performance as cocatalysts in ethylene polymerization. The replication of the catalyst morphology was found in the resultant polyethylene.
摘要In situ FT-IR of SiO2-supported (pph3)Hpt(μ-pph2)(μ-CO)Mo(co)4heterobinuclear hydrido carbonyl catalyst in the CO hydrogenation condition has been investigated.
基金supported by the National Key R&D Program of China(Nos.2022YFB3504101 and 2022YFB3506200)the National Natural Science Foundation of China(Nos.22322601 and 22425601)the R&D Program of Beijing Municipal Education Commission(No.KZ202210005011)。
摘要The inherent irreducibility and limited sulfur dioxide tolerance of zeolites constrain oxygen exchange efficiency in palladium/zeolite catalysts,which can adversely affect their performance in methane combustion.Herein,a novel molecular sieve(Silicate-1,denoted as S-1)catalyst functionalized with rare earth oxide sites was developed for catalytic methane combustion.Although both Pd/S-1@CeO2-30(in which CeO2content was 30 wt.%)and Pd/S-1 catalysts demonstrated comparable initial catalytic activities,the Pd/S-1@CeO2-30 sample achieved a methane reaction rate of 114.0μmol/(gPd·s)and the highest TOFPd(0.033s-1),with a 90%methane conversion at 424℃ at a space velocity of 20,000 mL/(g h).The CeO2shell in Pd/S-1@CeO2-30 exhibited the superior longterm stability that was attributed to the redox property of CeO2,which could facilitate the provision of abundant oxygen species.As a result,the Pd/S-1@CeO2-30 catalyst maintained stable performance in 10,000-ppm CH4methane combustion at 400℃ and retained a high CH4conversion efficiency even under exposure to 50 ppm SO2.Similarly,Ce0.6Zr0.4O2or Sm2O3shell also demonstrated comparable SO2resistance.Detailed characterization results revealed that CeO2acted as an exceptional redox center,significantly enhanced SO2adsorption,and effectively inhibited the poisoning of the active PdO sites by SO2,leading to a notable improvement in sulfur dioxide tolerance.These findings highlighted the critical role of the core-shell structure in enhancing catalyst resistance to SO2poisoning during methane combustion.The present work provides valuable insights into the appropriate designing of advanced core-shell catalysts with improved durability and performance in the sulfur dioxide-containing environments.