分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-08
Xu, W [Xu, Wei][ 1,2 ]
Lin, C [Lin, Chao][ 1 ]
Liu, H [Liu, Huan][ 1 ]
Yu, HB [Yu, Hongbo][ 1 ]
Tao, K [Tao, Kai][ 1 ]
Zhou, SH [Zhou, Shenghu][ 1 ]
摘要： Tungsten substituted mesoporous FDU-12 (W-FDU-12) catalysts were synthesized by a one-pot hydrothermal process using F127 as the structure directing agent. The studies of TEM, SAXS and BET illustrated that the highly ordered mesoporous structure of FDU-12 was maintained in the doped W-FDU-12 samples. XPS studies revealed that a high concentration of W5+ species appeared in doped W-FDU-12 catalysts whereas supported WO3/FDU-12 and WO3/SiO2 catalysts only contained W6+ species. Tandem catalytic conversion of 1-butene and ethene to propene through isomerization of 1-butene to 2-butene and consecutive cross metathesis of 2-butene and ethene in a fixed-bed reactor at different temperatures and atmospheric pressure was used to evaluate the catalytic performance of the W-FDU-12 catalyst, combined with MgO. The catalytic results showed that the doped W-FDU-12 illustrated a superior catalytic performance relative to the supported WO3/FDU-12 and WO3/SiO2 catalysts. The higher metathesis activity of W-FDU-12 catalysts can be ascribed to the good dispersion of W species and the incorporation of W species into the framework of FDU-12, forming a substantial amount of W5+, which was beneficial for the cross metathesis of 2-butene and ethene to propene.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-02
Liu, H [Liu, Huan][ 1,2 ]
Tao, K [Tao, Kai][ 1 ]
Zhang, PP [Zhang, Peipei][ 1 ]
Xu, W [Xu, Wei][ 1 ]
Zhou, SH [Zhou, Shenghu][ 1 ]
摘要： Ordered tungsten and aluminum co-doped mesoporous KIT-6 catalysts (W-Al-KIT-6) with different Si/Al molar ratios were successfully synthesized by a one-pot synthesis method. The obtained W-Al-KIT-6 catalysts were tested for catalytic conversion of 1-butene and ethene to propene via isomerization of 1-butene to 2-butene and subsequent cross metathesis of 2-butene and ethene. Various characterization techniques, such as ICP-OES, XRD, BET, TEM, Raman, XPS and NH3-TPD, were used to characterize the catalysts. The introduction of Al did not change the mesoporous structure of KIT-6 when the nominal Si/Al was 10, 20 or 30. Moreover, the sample demonstrated a larger amount of acidic sites. The W-Al-KIT-6 catalysts with suitable Si/Al ratios illustrated a superior catalytic performance to W-KIT-6 catalyst. The origin of catalytic performance enhancement over W-Al-KIT-6 catalysts is preliminarily discussed and ascribed to the highly disperse W species and a large amount of acidic sites. The acidic sites were formed by the introduction of a suitable amount of Al in the W-KIT-6 framework, which accelerated the isomerization of 1-butene to 2-butene and promoted the cross metathesis of 2-butene and ethene to propene.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-02
Zhang, PP [Zhang, Peipei][ 1,2 ]
Hu, YB [Hu, Yibo][ 1 ]
Li, BH [Li, Baihai][ 3 ]
Zhang, QJ [Zhang, Qiuju][ 1 ]
Zhou, C [Zhou, Chen][ 1 ]
Yu, HB [Yu, Hongbo][ 1 ]
Zhang, XJ [Zhang, Xuejun][ 2 ]
Chen, L [Chen, Liang][ 1 ]
Eichhorn, B [Eichhorn, Bryan][ 4 ]
Zhou, SH [Zhou, Shenghu][ 1 ]
摘要： This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for p-chloronitrobenzene hydrogenation with H2. The 6−8 nm Pd@Pt octahedral NPs are prepared by a sequential reduction method, and the characterization results confirm that Pd@Pt octahedral NPs with one to four atomic Pt layers can be controllably synthesized. The Pd@Pt octahedral NPs with one atomic Pt layer demonstrate excellent structural stability with the maintenance of core−shell structures as well as high catalytic stability during cycle to cycle catalytic p-chloronitrobenzene hydrogenation reactions. The alumina-supported Pd@Pt octahedral NPs illustrate a superior catalytic performance relative to individual Pt and Pd and their physical mixtures. Theoretical calculations by density functional theory suggest that the unexpected structural stability for Pd@Pt octahedral NPs with thin Pt shells and their corresponding catalytic stability during hydrogenation reactions can be ascribed to the strong binding between Pt surfaces and reactants/products in catalytic reactions. The enhanced catalytic performance of Pd@Pt octahedral NPs possibly originates from the core−shell interaction, which adjusts the electronic state of surface Pt atoms to be suitable for selective p-chloronitrobenzene hydrogenation.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-05-02
Lin, C [Lin, Chao][ 1,2 ]
Tao, K [Tao, Kai][ 1 ]
Yu, HB [Yu, Hongbo][ 1 ]
Hua, DY [Hua, Dayin][ 2 ]
Zhou, SH [Zhou, Shenghu][ 1 ]
摘要： Molybdenum-doped mesoporous SBA-15, mesoporous SBA-15-supported MoO3/SBA-15, and traditional silica-supported MoO3/SiO2 were successfully synthesized. Various techniques, such as XRD, TEM, BET, UV-DRS, Raman, XPS and IR, were used to characterize the above obtained materials. The studies of TEM, XRD and BET confirmed that the highly ordered mesoporous structure of SBA-15 was maintained in the doped Mo-SBA-15 whereas supported MoO3/SBA-15 showed a significant reduction in surface area due to the deposition of MoO3 nanoparticles into the SBA-15 channels. XPS studies revealed that a high concen- tration of Mo5+ species appeared in doped Mo-SBA-15 whereas supported MoO3/SBA-15 and MoO3/SiO2 only contained Mo6+ species. The metathesis reaction of 1-butene and ethene to propene was used to evaluate the catalytic performance of Mo-containing materials. The doped Mo-SBA-15 illustrated a superior catalytic performance over the supported MoO3/SBA-15 and MoO3/SiO2 catalysts. The enhancement of catalytic performance for doped Mo-SBA-15 was assigned to the incorporation of Mo species into the SBA-15 framework. Due to the doping method, Mo-SBA-15 exhibited a well-ordered mesoporous struc- ture, a high surface area, and a high concentration of Mo5+ species, which is beneficial to the catalytic per- formance for metathesis reactions.
点击量
待评议
点击量
下载量
评论
