Ru-Sn/Al2O3 catalysts for selective hydrogenation of methyl esters. Influence of preparation methods and B addition on the metal function properties

MARIA A. SANCHEZ; VANINA A. MAZZIERI; MARIO R. SAD; RICARDO GRAU; CARLOS L. PIECK

J. Chem Technol Biotechnol

Society of Chemical Industry

Año: 2010 vol. 86 p. 447 - 453

1097-4660

BACKGROUND: Improvements in the selective hydrogenation of unsaturated fatty acid methyl esters in order to obtain unsaturated fatty alcohols have been attempted through the preparation and modification of supported group VIII metallic catalysts. Suitable catalysts appear to be those based on supported Ru modified by Sn. The influence of preparation and activation methods on the structural and electronic properties of the metallic phase and the effect of modifications to these properties on the catalytic performance of Ru–Sn/Al2O3 catalysts was studied regarding selective hydrogenation of carbonyl groups. RESULTS: Preparationmethods have amarked influence on the electronic state of Ru and its interaction with Sn. Temperatureprogrammed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR-CO) and X-ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater Ru–Sn interaction when compared with catalysts prepared by co-impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations-reduction) does not produce a strong Ru–Sn interaction. B-containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols. CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak Ru–Sn interaction do not show significant selectivity for the unsaturated alcohol. groups. RESULTS: Preparationmethods have amarked influence on the electronic state of Ru and its interaction with Sn. Temperatureprogrammed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR-CO) and X-ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater Ru–Sn interaction when compared with catalysts prepared by co-impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations-reduction) does not produce a strong Ru–Sn interaction. B-containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols. CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak Ru–Sn interaction do not show significant selectivity for the unsaturated alcohol. groups. RESULTS: Preparationmethods have amarked influence on the electronic state of Ru and its interaction with Sn. Temperatureprogrammed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR-CO) and X-ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater Ru–Sn interaction when compared with catalysts prepared by co-impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations-reduction) does not produce a strong Ru–Sn interaction. B-containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols. CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak Ru–Sn interaction do not show significant selectivity for the unsaturated alcohol. 2O3 catalysts was studied regarding selective hydrogenation of carbonyl groups. RESULTS: Preparationmethods have amarked influence on the electronic state of Ru and its interaction with Sn. Temperatureprogrammed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR-CO) and X-ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater Ru–Sn interaction when compared with catalysts prepared by co-impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations-reduction) does not produce a strong Ru–Sn interaction. B-containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols. CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak Ru–Sn interaction do not show significant selectivity for the unsaturated alcohol.