Indole Hydrodenitrogenation over Alumina and Silica–Alumina-Supported Sulfide Catalysts—Comparison with Quinoline

Abstract

A detailed kinetic model was proposed to analyze experimental data obtained from indole hydrodenitrogenation (HDN) over γ-Al2O3 and amorphous silica–alumina (ASA)-supported NiMo catalysts. The goal was to investigate the support acidity effects on indole HDN and compare with a recent study on quinoline HDN. Similarly to quinoline HDN, indole HDN occurred via hydrogenation of the aromatic ring, followed by N-ring opening and exocyclic C–N bond breaking. The high support acidity of NiMo­(P)/ASA exhibited a promoting effect for N-removal steps and adsorption of nitrogen compounds. However, in contrast to quinoline HDN, it did not clearly induce a positive effect for the hydrogenation step. The acidic function of ASA also favored the formation of byproducts such as toluene, cyclohexane, dimer, and trimer of indole. Catalytic conversion of a quinoline and indole mixture revealed a strong inhibiting effect of quinoline on indole HDN, whereas the inhibiting effect of indole on quinoline HDN was weak. The inhibition was weaker over NiMo­(P)/Al2O3 than over NiMo­(P)/ASA. This result is in agreement with a relative ranking of apparent adsorption constants of quinoline, indole, and their products on NiMo­(P)/Al2O3 and ASA.

Molecular-Level Insights into Coker/Straight-Run Gas Oil Hydrodenitrogenation by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…. This is certainly a reasonable hypothesis, since it is well known that the inhibition effect of nitrogen species is strongly correlated to their basicity 43,62 . In model molecule tests, we recently demonstrated the strong inhibiting effect of quinoline on the conversion of indole.…”

How Does an Acidic Support Affect the Hydrotreatment of a Gas Oil with High Nitrogen Content?

“…In both cases, the ASA-supported was less active in HDN and HDS than its Al 2 O 3 -supported analogue. We presume that the activity difference can be mainly attributed to inhibition by basic, but also by neutral nitrogen species, which are more strongly adsorbed on the ASA-catalyst 17,18 .…”

“…The NiMo(P)/Al 2 O 3 and NiMo(P)/ASA (Amorphous Silica-Alumina) catalysts were identical to those described and characterized in our previous works 17,18 . Their main characteristics are compiled in Table 1.…”

Accelerating Kinetic Parameter Identification by Extracting Information from Transient Data: A Hydroprocessing Study Case

“…Hydroprocessing kinetic modeling is a challenging and time-consuming task as the crude oils contain many compounds with complicated structures [6]. Diverse approaches for hydroprocessing modeling have been developed in the past such as the lumping technique [7][8][9][10][11][12], detailed kinetic modeling [13][14][15][16][17][18][19], and black-box approach [20][21][22][23]. The lumping technique, which consists of regrouping chemical compounds with similar properties, is the most common and widely used [24].…”