Mg-Ni supported on perlite as hydrogenation catalyst: Influence of Mg and Ni content

Abstract

Use of broken honeycomb-like expanded perlite as support for magnesium modified nickel catalysts in process of partial hydrogenation of sunflower oil was studied. By the use of the precipitation-deposition method, two groups of precursors were synthesized: different Ni/SiO2 mole ratios with constant Mg/Ni mole ratio 0.1, and different Mg/Ni mole ratios with constant Ni/SiO2 mole ratio 0.25. Characterizations of precursors were done (scanning electron microscopy, diffuse reflectance UV?Vis, infrared spectroscopy, N2-physisorption, temperature programmed reduction (TPR) and He-pycnometry) to determine the material differences, considering the change in morphology, structure, texture and reducibility with overall Ni and Mg content. In addition, TPR and hydrogen chemisorption were performed in order to estimate the temperature reduction range of supported precursors and the dispersion degree of nickel in reduced precursors, respectively. The interaction between Ni2+ and perlite support was established. Different reducibility and dispersion were obtained as a function of Ni/SiO2 and Mg/Ni mole ratios. After the precursor?s reduction and paraffin oil impregnation, the obtained catalysts were tested in a sunflower oil hydrogenation reaction. Catalyst activity was monitored through the decrease of the refractive index and hydrogen consumption that gave the insight that the influence on catalyst activity represents the accessibility of triacylglycerols and not always the hydrogen determined dispersion degree.