Liquid-Phase Hydrogenation Kinetics of Multicomponent Aromatic Mixtures on Ni/Al₂O₃

Abstract

The hydrogenation reactivity of some aromatic compounds used to model diesel fractions was examined under sulfur-free conditions. Reactions of toluene, 1,2,3,4-tetrahydronaphthalene (tetralin), and naphthalene, separately and as mixtures, were studied using a commercial Ni/ Al 2 O 3 catalyst. The reactivity decreased in the following order: naphthalene . tetralin > toluene. Because of competitive adsorption and subsequent inhibition, naphthalene severely reduced the other hydrogenation rates in mixtures, whereas the hydrogenation rate of naphthalene was little affected by the concentration of toluene or tetralin. A kinetic model based on the general form of the Langmuir-Hinshelwood equation was developed. The activation energies of toluene, tetralin, and naphthalene were found to be 52.9, 40.4, and 58.7 kJ/mol, respectively, and the reaction orders of the monoaromatic and diaromatic compounds were about 1.4 and 2.1, respectively. Furthermore, simulations showed that the reaction kinetics in mixtures can be successfully described with models based on single-compound experiments, if surface-concentration terms (K i c i ) for all aromatics are included in the rate equations.

Competitive hydrogenation of poly-aromatic hydrocarbons on sulfur-resistant bimetallic Pt-Pd catalysts

“…Based on this differences one may expect that TL can only start being hydrogenated when essentially all the PHE has been removed from the feed. In line with this conclusion, the inhibition of TL hydrogenation in [45]. In both cases, the strong inhibition of hydrogenation of lighter aromatics by the presence of heavier aromatics was ascribed to inhibited adsorption due to site competition.…”

Hydrocracking of Fischer‐Tropsch wax and its mixtures with heavy vacuum gas oil

“…Note that the catalyst employed in this study is designed for hydrocracking of heavy oil feedstocks to enhance aromatic saturation. The paraffinic wax may not have been converted completely due to competitive adsorption during the reaction period when the F‐T wax/HVGO blending ratio was lower than 50/50 (g/g), which resulted in the presence of unconverted wax particles suspended in the liquid product …”

“…The waxes are relatively non‐polar and, therefore, may be kinetically disadvantaged. In multicomponent mixtures, the competitive adsorption of aromatics affects the hydrogenation rates due to the differences in absorption coefficients of the components . It is expected that the polar components from HVGO (i.e., aromatics and polars) would be easily adsorbed on the catalyst surface.…”

Vanadium substituted SBA‐15 supported bimetallic Pt, Pd catalysts for hydrogenation of toluene to methylcyclohexane

“…Activation energy was found to be 51.22 kJ/mol using Pt (0.15 wt %)-Pd (0.15 wt %)/V-SBA-15 catalyst indicates that the catalyst has a higher activity. [24] Coughlan and Keane Ni/Y-zeolite 78.2 [25] Lylykangas et al Ni/Al 2 O 3 52.9 [26] Rousset et al Pt-Pd/g-Al 2 O 3 44 AE 6 [27] Present study Pt-Pd/SBA-15 71.64 Present study Pt-Pd/V-SBA-15 51.22…”