Yuliya S. Demidova

Hydrogenation of Pentanoic Acid into Pentanol Over Ir and Ir-Re Catalysts: Effect of Support and Ir Dispersion

Liquid phase pentanoic acid hydrogenation in decane as a solvent (180 oC, hydrogen pressure 25 bar) was studied over monometallic Ir and bimetallic Ir-Re catalysts supported on alumina, ceria and zirconia, as well as carbon support Sibunit. Before catalytic test all catalysts were preliminary treated in Н2 at 415 oC during 5 h. An XPS study revealed predominant metallic state for Ir in studied catalysts while Re was partially oxidized. Conversion of pentanoic acid changed in the row Ir/CeO2 < Ir/ZrO2 < IrRe/ZrO2 < IrRe/Al2O3 ~ IrRe/C. Selectivity to pentanol was elevated over bimetallic catalysts in the sequence Ir/Al2O3 < Ir/CeO2 ~ Ir/ZrO2 < IrRe/ZrO2 < IrRe/Al2O3 ~ IrRe/C. It was shown that doping of Ir with Re gives a rise of pentanoic acid conversion and selectivity to pentanol in the absence of byside decarboxylation reaction. A series of the most active catalyst IrRe/Al2O3 was prepared varying Ir particle size from 0.8 to 1.7 nm as verified by TEM. Both pentanoic acid conversion and selectivity to pentanol over IrRe/Al2O3 catalyst increased with an increase of mean Ir particle size.

Liquid Phase Pentanol Guerbet-Markovnikov Condensation Over VIII Group Metals

Liquid phase pentanol condensation in solutions of nonpolar hydrocarbons as well as in solventfree conditions was studied in the presence of platinum group metals (platinum, palladium, iridium, ruthenium, and rhodium) supported on mesoporous carbon support Sibunit as well as on metal oxides – alumina, zirconia and ceria. This reaction was carried out in a batch mode in the temperature range 140-200 °C, under nitrogen pressure 1 – 10 bar in the presence of catalysts and a base – NaOH. It was shown that pentanol condensation mainly resulted in formation of the target product 2-propylheptanol (Guerbet alcohol), whereas pentanal, 2-propyl-2-heptenal, 2-propyl-1-heptanal, 2-propyl-1-heptenol were observed in minor quantities. The effect of metals as catalysts and reaction conditions on pentanol conversion and selectivity to 2-propylheptanol was studied. The reaction temperature increase not only as expected accelerates the reaction rate but in addition improves selectivity to 2-propylheptanol. Conversion of pentanol increased in the row Ir/CeO2 << Rh/Al2O3 < Pd/ZrO2 < Ru/C < Ir/C < Pd/C < Pt/C < Pt/Al2O3. Selectivity to 2-propylheptanol was elevated over metallic catalysts in the sequence Ir/CeO2 << Ir/C < Ru/C < Rh/Al2O3 ~ Pd/C ~ Pt/C ~ Pd/ZrO2 ~ Pt/Al2O3 being substantially influenced by temperature increase. The highest yield of 2-propylheptanol under comparable conditions was demonstrated for Pd/C, Pt/C и Pt/Al2O3 catalysts.