Photocatalytic oxidative desulfurization of dibenzothiophene by C/TiO₂@MCM-41 nanoparticles under visible light and mild conditions

Abstract

Today, due to the environmental pressures on the sulfur content of gasoline and fuel cell applications, refineries need a very deep desulfurization process to reach the ultra-low sulfur diesel (ULSD, 1 ppm). In this research, dibenzothiophene (DBT) in n-octane solution (as a diesel fuel model) was completely converted into biphenyl by visible light irradiation in the presence of C/TiO 2 @MCM-41 (CTM-41) as a photocatalyst under mild conditions. For the first time, the conversion was carried out through oxidation in one phase without using oxidant. For synthesizing CTM-41, tetra-butylorthotitanate was used as a precursor of Ti. Carbon species were identified in CTM-41 by X-ray photoelectron spectroscopy and UV-Vis spectroscopy. The self-doped carbon in CTM-41 was attributed to the tetra-butylorthotitanate used as a precursor of Ti. In the synthesis process, there was no carbon precursor addition. The formation of two types of carbon (carbonate species and coke-like structure in lattice of TiO 2 ) is responsible for the visible photocatalytic activity of the catalyst. The samples were characterized by X-ray diffraction, FTIR and UV-Vis spectroscopy. The specific surface areas of the prepared catalysts determined by the nitrogen adsorption-desorption isotherm at 77 K were 922.42 m 2 g À1 and 767.54 m 2 g À1 . The GC-MS analysis confirmed the conversion of DBT to biphenyl. Based on the experimental results, the hole and hydroxyl radical as reactive species in the proposed mechanism played the key roles in the photocatalytic desulfurization process.

Synthesis and characterization of N-doped TiO 2 nanoparticles and their application in photocatalytic oxidation of dibenzothiophene under visible light

“…Therefore, the presence of more hydroxyl radicals culminates to higher photocatalytic performance [9,31].…”

“…It is reported that superoxide anion radicals are less active than hydroxyl radicals for DBT oxidation under visible light [31,35]. Therefore, the photoactivity of NTiO 2 for DBT oxidation is dramatically dependent on the hydroxyl radical generation rate.…”

Modification of C/TiO2@MCM-41 with nickel nanoparticles for photocatalytic desulfurization enhancement of a diesel fuel model under visible light

“…In our previous work [16], the formation of an ordered mesoporous structure of CTM-41 was confirmed. It was also indicated the presence of anatase (isolated Ti-oxide moieties in CTM-41) and tetrahedrally coordinated Ti oxide moieties (Ti 4+ ) within the framework of the CTM-41 [20][21][22].…”

“…CTM-41 nanocomposite was prepared according to our previous work [16]. The pH pzc of CTM-41 was determined at 3 by using the drift method [17].…”

“…Recently, we carried out ODS technique for photodesulfurization of DBT with CTM-41 [16]. The objective of the present study is to improve the desulfurization performance by deposition of Ni nanoparticles on CTM-41.…”