The cumbersome air isolation process is one of the main constraints in the development of linear α-olefins prepared by ethylene oligomerization. An effective way to solve this problem is to eliminate the use of an alkyl-aluminum cocatalyst. Herein, two forms of Versailles/Santa Barbara-5 (VSB-5) (VSB-5-H3PO4 and VSB-5-NaH2PO2) are prepared and used as heterogeneous catalysts in ethylene oligomerization in the presence of LiAlH4 as a cocatalyst. Compared to other Ni-MOFs and Ni silica–aluminate catalysts, VSB-5s maintain a wider distribution of Linear α-olefin (LAO) products at relatively high activity. In the reuse test of the catalyst, the Al species from LiAlH4 cover the surface of the catalyst and decrease its activity, which could be removed by acid treatment. In situ IR studies show that active centers for ethylene oligomerization may form in VSB-5 assisted by LiAlH4. In addition, a Cossee–Arlman-type mechanism is proposed.
The nickel phosphate molecular sieve VSB-5 as an electrode material for supercapacitors is investigated by cyclic voltammetry (CV) and chronopotentiometry in alkaline media . The VSB-5 shows high specific capacitance and excellent cycling stability. The specific capacitance of VSB-5 is 2740 F g −1 at a current density of 3 A g −1 and there is no significant reduction in Coulombic efficiency after 3000 cycles at 30 A g −1 . In comparison with mesoporous nickel phosphate NiPO, porous nickel hydroxide and mesoporous nickel oxide, this remarkable electrochemical performance of VSB-5 will make nickel phosphate material a promising new electrode material for high performance supercapacitors.
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