Controllable Preparation Of Novel Nickel-based Nano Catalysts And Their Applications In Hydrogenation

Catalytic hydrogenation is an atom economic reaction and accords with the development demand of green chemical engineering. It has attracted much attention in recent years. Preparation and application of high efficient and stable catalysts are believed as the key spot of catalytic hydrogenation. Recently, nano catalysts have been widely applied in catalytic hydrogenation owing to their high surface area and extraordinary catalytic properties. Most of the catalysts used in catalytic hydrogenation were noble metal catalysts, including Pt, Pd, Rh based catalysts, and have achieved good results. However, the high price of noble metals limited further applications of such catalysts in industry. Thus, transition metal nickel, which was abundant and cheap, was selected as the active species in this work. A series of novel nickel-based nano catalysts were prepared and evaluated using cinnamic acid hydrogenation as a model reaction. The relationships between structures, morphologies of the prepared nano catalysts and their activities and stabilities were particularly investigated.Firstly, a novel nano NiB amorphous alloy catalyst(NiB-Gel-1-PEG800) was prepared by chemical reduction tuning by the confinement effect of supramolecular gelator. The synergistic effect between supramolecular gelator and polyethylene glycol(PEG800) can control the particle size and dispersion of the catalyst. It exhibited excellent catalytic performance in cinnamic acid hydrogenation with 100 % conversion and selectivity for hydrocinnamic acid.In order to solve the poor stability of nano Ni B amorphous alloy catalysts, a highly dispersed NiB amorphous alloy catalyst(NiB-Gel-1-TA-PEG800) was then prepared by a chemical reduction method with the co-addition of tannic acid, supramolecular gelator and PEG800. It exhibited good activity in cinnamic acid hydrogenation with 100 % conversion even at low reaction temperatures. This unsupported nano catalyst can be recycled effectively for five times in t-butanol, demonstrating its good stability.Finally, a novel multi-shell core-shell nanocomposite Fe3O4@nSiO2@NiPd-PVP@mSiO2 was prepared by the combination of a modified St?ber method, impregnation reduction and surfactant-templating method. It exhibited excellent catalytic performance in cinnamic acid hydrogenation under relatively mild reaction conditions in water. This catalyst can be recycled five times with no significant change of activity, demonstrating its good solvent adaptability and stability.