Hydrodeoxygenation of Isoeugenol over Alumina-Supported Ir, Pt, and Re Catalysts

Abstract

Hydrodeoxygenation (HDO) of isoeugenol (IE) was investigated using bimetallic iridium–rhenium and platinum–rhenium catalysts supported on alumina in the temperature and pressure ranges of 200–250 °C and 17–40 bar in nonpolar dodecane as a solvent. The main parameters were catalyst type, hydrogen pressure, and initial concentration. Nearly quantitative yield of the desired product, propylcyclohexane (PCH), at complete conversion in 240 min was obtained with Ir–Re/Al2O3 prepared by the deposition–precipitation method using 0.1 mol/L IE initial concentration. High iridium dispersion together with a modification effect of rhenium provided in situ formation of the IrRe active component with reproducible catalytic activity for selective HDO of IE to PCH. The reaction rate was shown to increase with the increasing initial IE concentration promoting also HDO and giving a higher liquid phase mass balance. Increasing hydrogen pressure benefits the PCH yield.

Hydrodeoxygenation of phenolic model compounds over zirconia supported Ir and Ni-catalysts

“…4 and 5). The hydrogenation of isoeugenol to dihydroeugenol was very rapid already during heating as confirmed earlier [26,32]. The transformation rate of isoeugenol after 1 min was, however very slow over Ni/ZrO 2 (Fig.…”

“…The reason for such lower GCLPA obtained by Ni/ZrO2 is its high activity for formation of gaseous products. Furthermore, Ir/ZrO 2 in conditions showing clearly that the selection of support and the amount of iridium are crucial for mass balance closure [26]. The low GCLPA values with the catalysts from this work is due to formation gaseous products [26].…”

“…One of the main aims was also to study the liquid phase mass balance closure, since in several papers [14,22,23], in addition to reactant conversion the product selectivity has been defined as the ratio between the products formed not reflecting the carbon balance in liquid phase. The mass balance closure, however, can only be found in a very few papers [7,[24][25][26][27]. The experiments in this study were performed using a low initial concentration of reactants, which, however, facilitated to directly compare the performance of ZrO 2 supported catalysts (Pt/C, Pd/C, Pt/H-Beta-300, Ir-Re/Al 2 O 3 , with other ones applied under the same conditions [5,7,12,26].…”

“…The mass balance closure, however, can only be found in a very few papers [7,[24][25][26][27]. The experiments in this study were performed using a low initial concentration of reactants, which, however, facilitated to directly compare the performance of ZrO 2 supported catalysts (Pt/C, Pd/C, Pt/H-Beta-300, Ir-Re/Al 2 O 3 , with other ones applied under the same conditions [5,7,12,26]. Zirconia was precalcined in air at 500 °C for 2 h before catalysts preparation.…”

NiMoS on alumina-USY zeolites for hydrotreating lignin dimers: effect of support acidity and cleavage of C–C bonds

“…have been studied extensively for HDO of phenols, [5][6][7][8][9][10][11][12] anisole, 9,[13][14][15][16] substituted phenols (cresols, guaiacols, syringols, eugenols, etc.) 6,9,[17][18][19][20][21][22][23][24][25][26][27][28][29][30] and lignin dimers. [31][32][33][34][35][36] The product distribution exclusively depends on the physicochemical properties of the chosen catalyst-support system and the employed reaction conditions.…”