Interaction between Cs and Ni2P/SiO2 for enhancing isobutane dehydrogenation in the presence of hydrogen

A series of 10 wt% Ni2P/SiO2 catalysts with cesium loading from 0 to 7.5 wt% were prepared by means of temperature-programmed reduction, and the effects of the cesium addition on the catalytic properties of the Ni2P/SiO2 catalyst for isobutane dehydrogenation have been investigated by reaction tests and some physicochemical characterizations such as TEM, XRD, H-2-TPR, XPS, H-2-TPD, NH3-TPD. It was found that cesium exists as CsOH on the catalyst surface, which partly covers the Ni2P surface or boundaries between Ni2P and SiO2 to decrease the acid strength and acid site number. XPS analysis suggests that Cs acts as an electronic promoter to Ni2P phase. The 6.5 wt% Cs-containing Ni2P/SiO2 catalyst showed the best catalytic performance and stability. After reaction for 4 h, selectivity toward isobutene of higher than 96 % was achieved with the corresponding conversion value of about 6.0 % at 733 K. The enhancement in the catalytic selectivity and stability of the Cs promoted catalysts is attributed to the decrease in acid strength and acid site number and the electrons transfer from Cs to Ni.