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Vapor-phase selective hydrogenation of maleic anhydride to succinic anhydride over Ni/TiO2 catalysts
Weitao Huo,Chunlei Zhang,Hongjing Yuan,Mingjun Jia,Chunli Ning,Yong Tang,Yi Zhang,Jiahuan Luo,Zhenlu Wang,Wenxiang Zhang 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
A series of supported Ni/TiO2 catalysts were prepared by incipient wetness impregnation method underdifferent calcination temperatures, and the as-prepared catalysts were characterized by X-ray diffraction(XRD), hydrogen temperature-programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy(XPS). The catalytic properties of these Ni/TiO2 catalysts were investigated in the vapor phasehydrogenation of maleic anhydride (MA) to succinic anhydride (SA). The results showed that thecatalytic activity and the selectivity of the Ni/TiO2 catalysts were strongly affected by the calcinationtemperature. The catalyst calcined at 1023 K showed a relatively higher SA selectivity of 96% at high MAconversion (96%) under the tested conditions (493 K and 0.2 MPa). The improvement of SA selectivitycould be mainly assigned to the presence of suitable metal–support interaction, which can play a role incatalytic property of active nickel species as electron promoter. Besides, the change of surface propertiesof TiO2 support with the increasing calcination temperatures, e.g., the decrease of Lewis acid sites, mightalso have some positive role in reducing the side-products like g-butyrolacetone (GBL).
Jianbiao Yan,Chunlei Zhang,Chunli Ning,Yong Tang,Yi Zhang,Lili Chen,Shuang Gao,Zhenlu Wang,Wenxiang Zhang 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.25 No.-
A cesium ion-containing catalyst, on an SBA-15 mesoporous molecular support, was prepared by the impregnation method and applied to the aldol condensation of methyl acetate with formaldehyde. The catalyst showed high catalytic activity in the condensation reaction. XRD characterization indicated that the cesium nitrate below 5 wt% loading was highly dispersed on the SBA-15 support. FT-IR and XPS results confirmed that a Si–O–Cs species was formed on the surface of the catalyst. Pyridine-IR verified that an L-acid site existed on the surface. The NH3-TPD and CO2-TPD results indicated that weak Lewis acid–base pairs were loaded on the surface, and these weak acid–base active sites might favor the aldol condensation reaction. The 5Cs/SBA-15 catalyst demonstrated the highest (48.4%) conversion of methyl acetate reported and 95.0% selectivity for methyl acrylate. The deactivated catalyst was completely regenerated by calcination. The catalyst was regenerated nine times with a total operation time of more than 60 h, and the initial conversion of methyl acetate and the selectivity for methyl acrylate did not change. The high catalytic activity was mainly due to the suitable strength of weak acid–base properties, which were rooted in the Si–O–Cs species on the surface of the support.