KF负载制备固体强碱的研究

Investigation on the Solid Strong Bases Derived from Supported KF

本文探讨了KF/Al_2O_3具有高碱性的原因.KF预吸附痕量H_2O后具有碱性且能化学吸附CO_2,但这些部分水合状态的F^-的碱性太弱,还不能催化丁烯异构化反应.IR和TPDE结果证实KF/Al_2O_3在丁烯异构化反应中的主要活性位具有[Al-OH…F^-]物种.这些强碱位可在高温脱羟而被破坏,导致KF/Al_2O_3的失活.KF被首次报道负载在AlPO_4-5上产生强碱位并能催化丁烯异构化反应.

In the present study,the reason for the high basicity of KF/Al2O3 and the nature of the basic active sites on KF/Al2O3 were explored. KF modification has also been applied to other metal oxides and molecular sieves. Hydration could produce some partially hydrated fluoride species and promote CO2 adsorption on KF and KF/CaF2, but the basicity of these species was too weak to catalyze 1 - butene isomerization at 273K. The effect of pretreatment temperature on the basicity of KF/Al2O3 was examined. Based on the results of Temperature Programmed Decomposition (TPDE), FTIR and probe reaction,the [Al-OH...F-] species were recognized to be the main active species on KF/Al2O3 in 1 - butene isomerization at 273K. Dehydroxylation at high temperature could destroy or suppress these species and caused deactivation on KF/Al2O3. KF was firstly reported to be supported on AlPO4-5 molecular sieve. Through the interaction with the support, KF modification can create strong basic sites on AlPO4 - 5 and catalyse the butene isomerization at 273K.