Facile synthesis and characterization of ordered mesostructured nickel catalysts

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 H2SO4 as the acid source. Both Ni-MH and Ni-MS contain uniform mesopore channels with a periodic mesochannel alignment (space group, p6mm). 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 SO42− (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 Ni2+. 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.

Graphical abstractA facile and rapid synthesis using different acid sources including nickel salts and initial stage reaction temperatures for the preparation of mesostructured catalysts is described. Nickel precursors were added midway during the self-assembly of a block copolymer and a silica precursor, leading to one-step production of highly ordered mesoporous nickel catalysts. These mesostructured nickel catalysts were characterized and applied to the hydrodechlorination (HDC) of 1,1,2-trichloroethane. Figure optionsDownload full-size imageDownload as PowerPoint slide