Nickle-Schiff base covalently grafted to UiO-66-NH2 as heterogeneous catalyst for ethylene oligomerization

Metal organic frameworks (MOFs) UiO-66-NH2 had been modified by reaction of pyridine-2-carboxaldehyde with the amino groups to form a pyridineimine that act as ligand of metal Ni. The UiO-66-NH2 grafted pyridineimine nickel catalyst of post synthetic modification was assessed by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), inductively coupled plasma mass spectrometry (ICP-MS) and nitrogen adsorption-desorption, and the catalytic performance of the UiO-66-NH2 grafted pyridineimine nickel catalyst in ethylene oligomerization was investigated. The results showed that the catalyst structure, reaction temperature, Al/Ni molar ratio and reaction pressure had a significant effect on the catalytic activity and products selectivity. The catalytic activity of 3.76 x 10(5) g.(mol Ni.h)(-1) and 75.94% selectivity of butene were obtained when the reaction temperature was 25 degrees C, Al/Ni molar ratio was 1000 and reaction pressure was 1.2 MPa.

Automated summary

Metal organic frameworks UiO-66-NH2 were modified by reacting with amino groups to form a pyridineimine ligand for nickel catalyst. The catalytic performance in ethylene oligomerization was influenced significantly by catalyst structure, reaction temperature, Al/Ni molar ratio, and reaction pressure. Optimal conditions yielded a catalytic activity of 3.76 x 10(5) g.(mol Ni.h)(-1) with 75.94% selectivity towards butene at 25 degrees C, Al/Ni molar ratio of 1000, and reaction pressure of 1.2 MPa.