Preparation of a four-layer magnetic core–shell nanocomposite for the selective hydrogenation of cinnamic acid

A novel magnetic mesoporous four-layer core–shell nanocomposite Fe₃O₄@nSiO₂@ZrO₂@Ni–Co–B was successfully fabricated by the combination of a modified Stöber sol–gel and self-assemble method. A facile template-free approach was employed to introduce the zirconia shell, which was more efficient than the conventional surfactant-templating method for the introduction of the mesoporous silica shell. This nanocomposite was composed of a ferroferric oxide core, an inner dense silica shell and a mesoporous zirconia shell in sequence and an outer Ni–Co–B amorphous alloy shell, as demonstrated by transmission electron microscope, X-ray energy dispersive spectroscopy, and nitrogen adsorption–desorption. It exhibited excellent catalytic performance in the selective hydrogenation of cinnamic acid to hydrocinnamic acid with almost 100 % yield. Additionally, it can be easily separated from the reaction mixture by using an external magnetic field due to its proper magnetic property and recycled effectively for five consecutive runs, making it an attractive candidate in efficient hydrogenations.