Facile synthesis and characterization of ordered mesostructured nickel catalysts

Abstract

Nickel precursors were added midway during the self-assembly of a block copolymer and a silica precursor, leading to the rapid and facile production (one-step) of highly ordered mesoporous nickel catalysts. Ni-MH and Ni-MS were prepared using HCl or H 2SO 4 as the acid source. Both Ni-MH and Ni-MS contain uniform mesopore channels with a periodic mesochannel alignment (space group, p6 mm). Ni-MS contained smaller nickel particles than Ni-MH, as evidenced by XRD and TEM analyses. TEM images clearly show that NiO in Ni-MH is deposited along the mesopore channel. Both the critical dependence of the temperature used in the synthesis of Ni-MH on nickel loading and the increase in nickel loading resulting from the use of SO 4 2− (Ni-MS) as a counteranion indirectly suggest that the self-assembly of mesostructured nickel catalysts mainly involves an electrostatic pathway and complexation between the polyethylene oxide (PEO) branch in P123 and Ni 2+. The routes for the self-assembly appear to largely involve electrostatic interactions in the case of Ni-MS and coordination by PEO in the case of Ni-MH. The morphologies of the Ni-MH and Ni-MS catalysts can be manipulated by varying the reaction temperature used, thus permitting the production of uniform rod-like forms or uniform spherical particles. As the reaction temperature is increased, both Ni-MH and Ni-MS appear to have a more curved shape in both meso and macroscopic views.