Elsevier

Applied Surface Science

Volume 569, 15 December 2021, 151086
Applied Surface Science

Full Length Article
Oxidative desulfurization of dibenzothiophene and simultaneous adsorption of products on BiOBr-C3N4/MCM-41 visible-light-driven core–shell nano photocatalyst

https://doi.org/10.1016/j.apsusc.2021.151086Get rights and content

Highlights

  • Synthesis of BiOBr-C3N4/MCM-41 visible-light-driven core–shell nano photocatalyst.

  • Photooxidation of DBT and adsorption of products simultanously on BiOBr-C3N4/MCM-41.

  • Study on the effect of BiOBr content in BiOBr-C3N4/MCM-41 on DBT degradation.

  • Study on thr effect of operating conditions on DBT degradation efficiency.

  • Stability of BiOBr-C3N4/MCM-41 in photoxidation-adsorption of DBT afetr 4 cycles.

Abstract

In this study, different amounts of BiOBr (x = 0, 5, 10, 15 wt%) and 5% wt. of g-C3N4 were loaded on MCM-41 as core for photo oxidation of DBT and simultaneous adsorption of oxidation products. Among studied photocatalysts, the BiOBr-C3N4/MCM-41 photocatalyst with 10% wt. of BiOBr indicated the highest activity so that this sample reduced DBT concentration to the lowest value of C/C0 = 0.08 after 150 min irradiation of visible light. The characterization of the as prepared photocatalysts by XRD, FESEM, TEM, FTIR, BET-BJH, UV–Vis DRS, and PL analyses revealed that this achievement was due to the highest amount of structural defects and the strongest interaction between BiOBr-C3N4 shell and MCM-41 core in this sample. Moreover, this sample indicated the lowest recombination rate of charge carriers, the narrowest band gap, and high porosity that enhanced the photocatalytic efficiency. However, this sample lost 18% of initial activity after four successive cycles of photo oxidation-adsorption that based on FTIR and BET-BJH was because of plugging of pores by DBT sulfones.

Introduction

Although fossil fuels have been playing a dominant role in developing modern life, the combustion of sulfur compounds such as disulfide, thiophene, dibenzothiophene, and their derivatives in fossil fuels releases sulfur oxides (SOx) into the atmosphere which are gradually causing acid rain, acid fog, haze, and other environmental issues [1], [2], [3]. Therefore, essential strategies should be taken to remove the sulfur compounds from fossil fuels.

Hydrodesulfurization (HDS) which is a conventional technique to reduce sulfur components from liquid fuels, operates under high temperature (320–380 °C) and high pressures (3–7 MPa) and needs large amounts of H2 [4], [5]. Nevertheless, this technique is less effective in removing sterically hindered compounds such as dibenzothiophene (DBT) and its derivatives [6]. To achieve ultra-deep desulfurization, other methods have been employed such as extractive desulfurization (EDS) [7], [8], biodesulfurization (BDS) [9], [10], and adsorptive desulfurization [11].

Oxidative desulfurization by a catalyst or photocatalyst is a promising strategy for degradation of sulfuric components in the liquid fuel. While catalytic desulfurization has been indicated promising results in oxidative desulfurization [12], [13], [14], [15], photocatalytic desulfurization because of milder operating conditions, keeping the octane number at high level, high efficiency, and using sustainable energy of sun is suitable particularly in the case of in situ desulfurization of marine fuels on board [16], [17]. In this process, in the presence of a photocatalyst and an oxidant, sulfur compounds are converted to the corresponding polar sulfones. Dipole-dipole interactions facilitate the separation of sulfones by solvent extraction [18], [19], however, the common solvents are expensive and harm the environment. Another alternative with outstanding economic and environmental benefits is adsorption of oxidation products on a porous solid. In this case, combining two stages of oxidation and adsorption in one vessel on the same material is a new development. As a result, the used photocatalyst should have dual functionality both in the oxidation of sulfur compounds and in the adsorption of oxidation products.

With regard to the photocatalytic phases, graphitic nitride carbon (g-C3N4), as a well-known polymer, has attracted much interest due to thermal stability, electronic characteristics, suitable band gap energy (2.7 eV), and low cost [7], [20]. g-C3N4 can be obtained through a simple one-step polymerization of urea, thiourea, melamine, or dicyandiamide [7], [21], [22]. However, this material has a high recombination rate of the electron-hole pairs [20]. Strategies such as morphological control [23], [24], element-doping [25], and creating heterojunction with other semiconductors [26], [27], [28], [29] have been developed so far to overcome this drawback.

Among different semiconductors, bismuth-based ones are widely used for building a heterojunction with g-C3N4 in order to resolve the problem of fast recombination rate. BiOBr as a bismuth oxyholide has a lamellar structure, visible light response, high chemical stability, and low cost. While the heterojunction between BiOBr and g-C3N4 has been used in the photocatalytic treatment of wastewater [30], [31], [32], [33], to the best of our knowledge, this heterojunction has not been used in photocatalytic desulfurization to date.

Porous silica, which has a good background in the adsorption of polar sulfur compounds produced from oxidation, is a suitable choice for our needed support of bifunctional photocatalyst-adsorbent [34].

Due to the proper performance of core–shell structures in bifunctional purposes, in this study, g-C3N4-BiOBr with different BiOBr percentages were loaded on MCM-41 as core. The synthesized core–shell photocatalysts were investigated in the simultaneous oxidative-adsorptive desulfurization of DBT. X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Brunauer–Emmett–Teller (BET), Fourier Transform Infrared (FTIR), Energy Dispersive X-Ray (EDX), UV–Vis Diffuse Reflectance Spectroscopy (UV–Vis DRS), Photoluminescence (PL), and Transmission Electron Microscopy (TEM) analyses were used to characterize the as-prepared samples.

In the following, the effect of operating parameters, such as reaction temperature, the content of H2O2, DBT concentration, and the amount of catalyst, were investigated on the highly active photocatalyst. The stability of this sample also was tested during successive runs.

Section snippets

Materials

Dibenzothiophene (Sigma–Aldrich), hydrogen peroxide (Fisher Scientific, 30% v/v.), n-hexane (Sigma–Aldrich), sodium hydroxide (Sigma–Aldrich), tetraethyl orthosilicate (Sigma–Aldrich), hexadecyltrimethylammonium bromide (CTAB, Merck), ethanol (Merck), melamine (Merck), bismuth (III) nitrate pentahydrate (Sigma–Aldrich), and potassium bromide (Merck) were used as received without any further purification.

Preparation of MCM-41

MCM-41 was synthesized by a sol–gel method [35]. For this, 0.28 g of NaOH and 1 g of CTAB in

Structural characteristics of BiOBr-C3N4/MCM-41 photocatalyst-adsorbents

Fig. 1 shows X-ray diffraction patterns of as-synthesized BiOBr-C3N4/MCM-41 photocatalyst-adsorbents with different percentages of BiOBr (0%, 5%, 10% and 15% wt.). The diffraction peaks at 2θ of 10.9˚, 21.9˚, 25.2˚, 30.0˚, 31.2˚, 37.5˚, 44.6˚, 47.6˚, 50.6˚ and 54.0˚ can be well-indexed for (0 0 1), (0 0 2), (0 1 1), (0 1 2), (1 1 0), (1 1 2), (0 0 4), (0 1 4) and (1 2 1) planes of tetragonal BiOBr (JCPDS 96–901-1784), respectively. A shift at 2θ = 30˚ toward higher 2θs could be attributed to the decrease of unit

CRediT authorship contribution statement

Fahime Abedini: Conceptualization, Methodology, Data curation, Validation, Writing – original draft. Somaiyeh Allahyari: Supervision, Writing – review & editing, Funding acquisition, Project administration. : . Nader Rahemi: Supervision, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors gratefully acknowledge financial support from Sahand University of Technology.

References (80)

  • P. Sikarwar et al.

    Catalytic oxidative desulfurization of DBT using green catalyst (Mo/MCM-41) derived from coal fly ash

    J. Environ. Chem. Eng.

    (2018)
  • D. Huang et al.

    Direct synthesis of mesoporous TiO2 and its catalytic performance in DBT oxidative desulfurization

    Microporous Mesoporous Mater.

    (2008)
  • L. Guo et al.

    Magnetically recyclable Fe3O4@SiO2/Bi2WO6/Bi2S3 with visible-light-driven photocatalytic oxidative desulfurization

    Mater. Res. Bull.

    (2019)
  • Y. Zhu et al.

    Mesoporous graphitic carbon nitride as photo-catalyst for oxidative desulfurization with oxygen

    Catal. Commun.

    (2016)
  • X. Li et al.

    Integrated nanostructures of CeO2/attapulgite/g-C3N4 as efficient catalyst for photocatalytic desulfurization: mechanism, kinetics and influencing factors

    Chem. Eng. J.

    (2017)
  • Y. Li et al.

    Seed-induced growing various TiO2 nanostructures on g-C3N4 nanosheets with much enhanced photocatalytic activity under visible light

    J. Hazard. Mater.

    (2015)
  • M. Zhang et al.

    Enhancement of visible light photocatalytic activities via porous structure of g-C3N4

    Appl. Catal. B

    (2014)
  • Y. Dong et al.

    Morphological control of tubular g-C3N4 and their visible-light photocatalytic properties

    Mater. Lett.

    (2017)
  • F. Guo et al.

    Z-scheme heterojunction g-C3N4@PDA/BiOBr with biomimetic polydopamine as electron transfer mediators for enhanced visible-light driven degradation of sulfamethoxazole

    Chem. Eng. J.

    (2020)
  • X. Wei et al.

    Three-dimensional flower heterojunction g-C3N4/Ag/ZnO composed of ultrathin nanosheets with enhanced photocatalytic performance

    J. Photochem. Photobiol. A: Chem.

    (2020)
  • B. Zhang et al.

    In situ synthesis of ultrafine TiO2 nanoparticles modified g-C3N4 heterojunction photocatalyst with enhanced photocatalytic activity

    Sep. Purif. Technol.

    (2020)
  • K. Perumal et al.

    Hydrothermal assisted precipitation synthesis of highly stable g-C3N4/BiOBr/CdS photocatalyst with enhanced visible light photocatalytic degradation of tetracycline

    Diam. Relat. Mater.

    (2020)
  • Y. Shang et al.

    Constructing BiOBr/CoOx/g-C3N4 Z-scheme photocatalyst with CoOx as both redox mediator and cocatalyst for phenol degradation

    J. Alloy. Compd.

    (2021)
  • Z. Shi et al.

    Fabrication of g-C3N4/BiOBr heterojunctions on carbon fibers as weaveable photocatalyst for degrading tetracycline hydrochloride under visible light

    Chem. Eng. J.

    (2020)
  • L. Wang et al.

    Facile constructing plasmonic Z-scheme Au NPs/g-C3N4/BiOBr for enhanced visible light photocatalytic activity

    J. Fuel Chem. Technolo.

    (2019)
  • M. Chen et al.

    Amine modified nano-sized hierarchical hollow system for highly effective and stable oxidative-adsorptive desulfurization

    Fuel

    (2020)
  • Q. He et al.

    An anticancer drug delivery system based on surfactant-templated mesoporous silica nanoparticles

    Biomaterials

    (2010)
  • Y. Yu et al.

    Direct microwave synthesis of graphitic C3N4 with improved visible-light photocatalytic activity

    Ceram. Int.

    (2016)
  • J. Robertson et al.

    Photooxidation of dibenzothiophene on TiO2/hectorite thin films layered catalyst

    J. Colloid Interface Sci.

    (2006)
  • X.N. Pham et al.

    Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

    Adv. Powder Technol.

    (2018)
  • K. Khaledi et al.

    On the catalytic properties and performance of core-shell ZSM-5@MnO nanocatalyst used in conversion of methanol to light olefins

    Microporous Mesoporous Mater.

    (2017)
  • M. Wen et al.

    Monolithic metal-fiber@HZSM-5 core–shell catalysts for methanol-to-propylene

    Microporous Mesoporous Mater.

    (2015)
  • Z. Zhang et al.

    Low-temperature combustion synthesis of Bi2WO6 nanoparticles as a visible-light-driven photocatalyst

    J. Hazard. Mater.

    (2010)
  • A.A. Ibrahim et al.

    Synthesis of sulfated zirconium supported MCM-41 composite with high-rate adsorption of methylene blue and excellent heterogeneous catalyst

    Colloids Surf. A: Physicochem. Eng. Asp.

    (2021)
  • S. Sharma et al.

    Synthesis of MCM-41 supported cobalt (II) complex for the formation of polyhydroquinoline derivatives

    Polyhedron

    (2021)
  • X. Yang et al.

    Synthesis of Zr-MCM-41 by the assistance of sodium chloride in the self-generated acid conditions

    Mater. Chem. Phys.

    (2010)
  • X.-N. Wei et al.

    Fabrication of the novel core-shell MCM-41@mTiO2 composite microspheres with large specific surface area for enhanced photocatalytic degradation of dinitro butyl phenol (DNBP)

    Appl. Surf. Sci.

    (2016)
  • L. Yang et al.

    Accelerated photocatalytic oxidation of carbamazepine by a novel 3D hierarchical protonated g-C3N4/BiOBr heterojunction: performance and mechanism

    Appl. Surf. Sci.

    (2019)
  • E Rodrı́guez-Castellón et al.

    Textural and structural properties and surface acidity characterization of mesoporous silica-zirconia molecular sieves

    J. Solid State Chem.

    (2003)
  • T. Lehmann et al.

    Physico-chemical characterization of Ni/MCM-41 synthesized by a template ion exchange approach

    Microporous Mesoporous Mater.

    (2012)
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