Kinetic and Mechanistic Analysis of Dibenzothiophene Hydrodesulfurization on Ti-SBA-15–NiMo Catalysts

Abstract

MoS 2 -based catalysts are the most commonly used systems for the hydrodesulfurization (HDS) process on an industrial scale. Different methods were employed to enhance the efficiency of the catalysts, which include changes in catalyst support and doping agents as well as tuning the dispersion of the MoS 2 phase using various synthetic techniques. In this work, we report the kinetic and mechanistic analysis of HDS of dibenzothiophene (DBT) for different NiMo-supported Ti-SBA-15 catalysts prepared by (1) direct single-pot (SP) synthesis and (2) impregnations of the NiMo phase into the Ti-SBA-15 support. Both methods were also repeated with and without the citric acid (CA) loading to achieve higher dispersion of the active metal sites. Kinetic modeling was performed to two "parallel−series" reactions of DBT, direct desulfurization (DDS) and hydrogenation (HYD), both leading to the final product of cyclohexylbenzene. Kinetic analysis reveals the considerable influence of the catalyst preparation methods to both steps of HDS of DBT. We found that apparent rate constants for DDS k 1 ′ are highly dependent upon the employed synthetic method, while the effect of CA has a high contribution to the apparent rate constants for the conversion of partially hydrogenated dibenzothiophene intermediate, k 4 ′.

Sono-Assisted Synthesis and Kinetic Modeling of Nanocrystallite Silicalite-1-NiMo Catalysts for Hydrodesulfurization of Dibenzothiophene: Role of Sonication Time on Support Mesoporosity and Catalytic Activity

“…The effect of sonication time on the silicalite-1-supported NiMo catalysts' activity and selectivity was further studied by using the kinetic modeling. 44 Based on our previous studies and the concentration trends of the species (i.e., DBT, BP, and CHB) in the present study, we propose the same triangular reaction scheme shown in Figure 9. 17 In this scheme, DBT is converted to BP via the DDS route at a specific reaction rate k 1 , whereas CHB is formed via a parallel HYD reaction step with a specific reaction rate k 2 .…”

“…The effect of sonication time on the silicalite-1-supported NiMo catalysts’ activity and selectivity was further studied by using the kinetic modeling . Based on our previous studies and the concentration trends of the species (i.e., DBT, BP, and CHB) in the present study, we propose the same triangular reaction scheme shown in Figure …”

Catalytic Performance of NiMoS Supported on (Zr)SBA-15 for Hydrodesulfurization of Diesel: Insight into a One-Step Calcination and Reduction Strategy during Sulfidation

“…The rate of reaction generally increases by increasing the temperature of the reaction, due to more collision within the reactive molecules. 61 As shown in Table 5, the increase in temperature of the HDS reaction resulted in the decrease in the total amount of organosulfur compounds (DBT and DMDBT) present in the fuel. The conversion of sulfur-polluted fuel into a sulfur-free fuel is enhanced and favorable at 375 °C compared to that at lower reaction temperatures with desulfurization efficiencies of 99.5 and 92.4% for DBT and DMDBT, respectively (Figure 10).…”

Role of 3D Alumina Foam Support on the Formation and Dispersion of Active NiMoS Phase for Hydrodesulfurization Application

“…The kinetic studies were carried out on the supposition that the HDS reaction is pseudo-first order; therefore, first-order rate constants were calculated for both the DDS (k DDS (min −1 )) and the HYD (k HYD (min −1 )) reaction pathways, and the summation of both rate constants gives the HDS rate constant (k HDS (min −1 )). 43 The rate constants which were calculated after 0.5 h of the HDS reaction are summarized in Table S4. The k HDS for γ-Al 2 O 3 −NiMo catalyst is calculated as 5.4 × 10 −3 min −1 , while the k HDS for Al-F catalyst is 11.0 × 10 −3 min −1 .…”