Process Optimization for Catalytic Oxidation of Dibenzothiophene over UiO-66-NH₂ by Using a Response Surface Methodology

Abstract

This research investigates the catalytic performance of a metal–organic framework (MOF) with a functionalized ligand—UiO-66-NH 2 —in the oxidative desulfurization of dibenzothiophene (DBT) in n -dodecane as a model fuel mixture (MFM). The solvothermally prepared catalyst was characterized by XRD, FTIR, 1 H NMR, SEM, TGA, and MP-AES analyses. A response surface methodology was employed for the experiment design and variable optimization using central composite design (CCD). The effects of reaction conditions on DBT removal efficiency, including temperature ( X 1 ), oxidant agent over sulfur (O/S) mass ratio ( X 2 ), and catalyst over sulfur (C/S) mass ratio ( X 3 ), were assessed. Optimal process conditions for sulfur removal were obtained when the temperature, O/S mass ratio, and C/S mass ratio were 72.6 °C, 1.62 mg/mg, and 12.1 mg/mg, respectively. Under these conditions, 89.7% of DBT was removed from the reaction mixture with a composite desirability score of 0.938. From the results, the temperature has the most significant effect on the oxidative desulfurization reaction. The model F values gave evidence that the quadratic model was well-fitted. The reusability of the MOF catalyst in the ODS reaction was tested and demonstrated a gradual loss of activity over four runs.

Deep Oxidative Desulfurization of Planar Compounds Over Functionalized Metal–Organic Framework UiO-66(Zr): An Optimization Study

“…ratio at 3.0 in four different temperature runs. Compared to the previous study, 30 highest DBT removal efficiency achieved was 89.7% when UiO-66-NH 2 (in the conditions of 72.6 °C temperature, 1.62 O/S mass ratio mg/mg, and 12.1 C/S mass ratio mg/mg) was used as the catalyst, which is lower than the yields in the case of UiO-66.…”

“…The deactivation mechanism of UiO-66 active sites for sequential cycles has been previously reported. 30 , 52 The reusability of UiO-66-OH and UiO-66 MOFs is shown in Figure S6 .…”

“…Sulfur removal efficiency for four multiple reactions demonstrates (Figure 9) that with a nearly The deactivation mechanism of UiO-66 active sites for sequential cycles has been previously reported. 30,52 The reusability of UiO-66-OH and UiO-66 MOFs is shown in Figure S6.…”

“…28,29 In previous studies, several metal−organic frameworks have been found to be active catalysts for oxidative desulfurization; however, it was claimed that UiO-66 obtained high sulfur removal efficiency in a shorter period of the process. 30 Previous reports on adsorption and oxidation efficiency of pristine-, amino-, and nitro-modified UiO-66 are summarized in Table 1:…”

“…Thus, far, there has been one report in our previous work, employing UiO-66-NH 2 as a catalyst on reaction variable assessment in the ODS reaction; 30 this research employed a more electron-rich ligand, aminoterephthalic acid, to modulate the catalytic activity of nodes and increase the potential for hydrogen bonding in pores via the NH 2 group.…”