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Highly dispersed Ni 2 P embedded in carbon framework with different phosphidation temperature was prepared through carbonizing Ni-alginate gel and followed by phosphidation with PPh 3 in liquid phase. The significant effects of phosphidation temperature on Ni 2 P particle size and catalytic properties for isobutane dehydrogenation to isobutene were investigated. The results showed that Ni 2 P catalyst derived from the Ni-alginate gel (Ni 2 P-ADC), consisting of Ni 2 P particles embedded in carbon walls, possessed smaller particle size and more active site compared with Ni 2 P catalyst supported on active carbon (Ni 2 P/AC) prepared by impregnation method. The Ni 2 P-ADC catalyst phosphorized at 578 K for 3 h exhibited the highest catalytic performance, with the corresponding selectivity of isobutene approaching 89% and conversion approaching 15% after reaction for 4.5 h at 833 K, whereas Ni 2 P/AC catalyst prepared by impregnation method displays a much lower catalytic activity. The improved catalytic performance of the Ni 2 P-ADC can be ascribed to the smaller and highly dispersed Ni 2 P particles incorporated into carbon framework resulting from Ni-alginate gel. [ABSTRACT FROM AUTHOR]

In this article, an environmentally friendly non-noble-metal class of Cs-Ni 2 P/active carbon (AC) catalyst was prepared and demonstrated to exhibit enhanced catalytic performance in isobutane dehydrogenation. The results of activity tests reveal that Ni/AC catalyst was highly active for isobutane cracking, which led to the formation of abundant methane and coke. After the introduction of phosphorus through impregnation with ammonium di-hydrogen phosphate and H 2 -temperature programmed reduction, undesired cracking reactions were effectively inhibited, and the selectivity to isobutene and stability of catalyst increased remarkably. The characterization results indicate that, after the addition of phosphorous, the improvement of dehydrogenation selectivity is ascribed to the partial positive charges carried on Ni surface in Ni 2 P particles, which decreases the strength of Ni C bond between Ni and carbonium-ion intermediates and the possibility of excessive dehydrogenation. In addition, Cs-modified Ni 2 P/AC catalysts display much higher catalytic performance as compared to Ni 2 P/AC catalyst. Cs-Ni 2 P-6.5 catalyst has the highest catalytic performance, and the selectivity to isobutene higher than 93% can be obtained even after 4 h reaction. The enhancement in catalytic performance of the Cs-modified catalysts is mainly attributed to the function of Cs to improve the dispersion of Ni 2 P particles, transfer electron from Cs to Ni, and decrease acid site number and strength. [ABSTRACT FROM AUTHOR]