Pham, X. N., Tran, D. L., Pham, T. D., Nguyen, Q. M., Thi, V. T. T., & Van, H. D. (2018). One-step synthesis, characterization and oxidative desulfurization of 12-tungstophosphoric heteropolyanions immobilized on amino functionalized SBA-15. Advanced Powder Technology, 29(1), 58-65. https://doi.org/10.1016/j.apt.2017.10.011 Peer reviewed version License (if available): CC BY-NC-ND Link to published version (if available): 10.1016/j.apt.2017.10.011 Link to publication record in Explore Bristol Research PDF-document This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at DOI: 10.1016/j.apt.2017.10.011. Please refer to any applicable terms of use of the publisher. University of Bristol - Explore Bristol Research General rights This document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/red/research-policy/pure/user-guides/ebr-terms/ APT 1754 No. of Pages 8, Model 5G 31 October 2017 Advanced Powder Technology xxx (2017) xxx–xxx 1 Contents lists available at ScienceDirect Advanced Powder Technology journal homepage: www.elsevier.com/locate/apt 2 Original Research Paper 7 4 One-step synthesis, characterization and oxidative desulfurization 8 5 of 12-tungstophosphoric heteropolyanions immobilized on amino 6 functionalized SBA-15 a,⇑ a a b b 9 Xuan Nui Pham , Dinh Linh Tran , Tuan Dat Pham , Quang Man Nguyen , Van Thi Tran Thi , c 10 Huan Doan Van 11 a Department of Chemical Engineering, Hanoi University of Mining and Geology, 18 Pho Vien, Duc Thang, Bac Tu Liem District, Hanoi, Viet Nam 12 b Department of Chemistry, Hue Science College, Hue University, 77 Nguyen Hue Str., Hue City, Viet Nam 13 c Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TH, United Kingdom 1415 16 article info abstract 1830 19 3À Article history: Keggin-type 12-tungstophosphoric [PW12O40] heteropolyanions were successfully immobilized onto 31 20 Received 14 July 2017 mesoporous material surface of SBA-15 functionalized using the (3-aminopropyl)triethoxysilane 32 21 Accepted 14 October 2017 (APTES) synthesized by one-pot co-condensation method, also called one-step synthesis. The synthesized 33 22 Available online xxxx À + PW -NH3-SBA-15 catalyst was characterized by XRD, N2 adsorption–desorption, FT-IR, TGA, SEM, TEM, 34 EDS, XPS methods. The results indicated that ordered hexagonal mesostructure for SBA-15 support 35 23 Keywords: was still maintained after being functionalized with amine groups, while the specific surface area of 36 24 Oxidative desulfurization SBA-15 was decreased. The active species of phosphotungstic acid H PW O (HPW) retained its 37 25 Dibenzothiophene 3 12 40 Keggin structure of the heteropolyanions on the amine-modified SBA-15. The PWÀ–+H N–SBA–15 cata- 38 26 Heteropoly acid 3 27 Functional mesoporous materials lyst exhibited a high catalytic activity for oxidative desulfurization process of sulfur-containing model 39 28 One-pot synthesis fuel. The dibenzothiophene (DBT) conversion of almost 100% was achieved with reaction conditions of 40 29 40 mg of catalyst dosage, 2 mL of hydrogen peroxide, 90 °C of reaction temperature, and 120 min of reac- 41 tion time. 42 Ó 2017 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights 43 reserved. 44 45 46 47 48 1. Introduction and aliphatic hydrocarbons, it has exhibited some inherent prob- 64 lems in treating sulfur-containing aromatic hydrocarbon com- 65 49 Organic compounds containing sulfur in fuels are the major pounds such as dibenzothiophene (DBT), benzothiophene (BT) 66 50 source of pollution. Emission of SOx from vehicle engine causes and their derivatives as the existence of benzene rings in molecular 67 51 acid rain, engine and pipeline corrosions, and catalysts poison in enhances their aromatic [3–5]. 68 52 the catalytic processes. Hence, the stringency of environmental In order to overcome this drawback, many other technologies 69 53 regulations drives the maximum reduction of sulfur content in have been applied such as oxidative desulfurization (ODS) [6–8], 70 54 fuel. For example, that content in the diesel in Europe and the adsorptive desulfurization [9], extraction by ionic liquids [10,11], 71 55 United States must be reduced to less than 10 and 15 ppmw, biodesulfurization [12]. 72 56 respectively [1]. To meet this requirement, many methods have Up to now, there are many studies on the use of appropriate 73 57 been applied in the field of deep – desulfurization. catalysts for sulfur removal by the oxidation [13–19]. Among the 74 58 Currently, conventional hydrodesulfurization (HDS) technology oxidation methods applied, oxidative desulfurization on the base 75 59 has been applied to remove sulfur from the liquid fuel. However, of tungsten as active species is one of the promising ways comple- 76 60 this technology requires the strict operating conditions, and takes ment HDS due to its mild operating conditions e.g.atmospheric 77 61 place in the reactor at high temperature (300–400 °C), high pres- pressure, no consumption of hydrogen, and high efficiency. Under 78 62 sure (3–6 Mpa), and in the presence of hydrogen [2]. Although it this process, sulfur-containing compounds can be selectively oxi- 79 63 is effective method for the removal of sulfur-containing cyclic dized to sulfoxides or sulfones in the presence of hydrogen perox- 80 ide as oxidative agent. The formation of sulfone and sulfoxide 81 compounds with the polar bonds of sulfur-oxygen (S@O), resulting 82 ⇑ Corresponding author. E-mail address: [email protected] (X.N. Pham). https://doi.org/10.1016/j.apt.2017.10.011 0921-8831/Ó 2017 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights reserved. Please cite this article in press as: X.N. Pham et al., One-step synthesis, characterization and oxidative desulfurization of 12-tungstophosphoric heteropolyanions immobilized on amino functionalized SBA-15, Advanced Powder Technology (2017), https://doi.org/10.1016/j.apt.2017.10.011 APT 1754 No. of Pages 8, Model 5G 31 October 2017 2 X.N. Pham et al. / Advanced Powder Technology xxx (2017) xxx–xxx 83 in their solubility in polar solvents and their extractability in non- °C, the final mixture was transferred to a Teflon-lined stainless 143 84 polar organic solvent [20]. steel atoclave for hydrothermal synthesis at 110 °C for 24 h. The 144 85 Recently, several research groups have developed silica sup- solid product synthesized was collected, washed by distilled water, 145 86 ported active tungsten species for oxidative desulfurization, such dried overnight at 80 °C, and calcined at 550 °C for 6 h with the 146 87 as W-MCM-41 [15], silica supported H3PMo12O40 [19] synthesized heating rate of 5 °C/min. The obtained sample was designated as 147 88 by direct one-pot method, MCM-41 supported (Bu4N)4H3(PW11O39) H2N-SBA-15 (M4). 148 89 [16], silica supported [(n-C8H17)3NCH3]2W2O11] [21]. Li et al. [22] 90 reported the using decatungstates [(C4H9)4N]4W10O32 in the ionic 2.3. The immobilization of HPW onto the NH2–SBA-15 silica support 149 À + 91 liquid of [Bmim]PF6 catalyzed for deep oxidative desulfurization (PW H3N -SBA-15) 150 92 of fuel oils. 93 Keggin structure type 12-tungstophosphoric heteropolyacid To increase the immobilization of HPW onto surface of H2N- 151 94 H3PW12O40 (HPW) is promising catalytic material because their SBA-15 material, in this study, triflic acid was used as the reagent 152 + 95 superacid properties with strong Bronsted acid sites, high proton protonating amine groups to create positively charged NH3 groups 153 96 mobility, redox activity, high thermal stability, and environmental on the support. As the result, there is the formation of electrostatic 154 + À 97 friendliness [23–25]. Polyoxometalate catalyst has been used for interaction between NH3 of support surface with PW of HPW. 155 98 oxidative desulfurization [26]. However, pure HPW materials as Immobilization of HPW on H2N-SBA-15 silica support was carried 156 99 the catalysts are hindered by their low specific surface area out as follows [33]:1gofH2N-SBA-15 was suspended in 50 mL of 157 100 (<10 m2/g), and high solubility in polar solvents in reaction system acetonitrile solvent, then 4 mL of triflic acid solution was added 158 101 which leads to the difficulty of catalysts recovery [27]. into the reaction mixture and refluxed at 80 °C for 5 h. After that 159 102 Immobilization of HPW by supporting HPW onto a solid porous the solid product was filtered, and was washed with acetonitril 160 103 substrate such as amorphous silica [28–30], carbon nanotubes [31] to remove the unreacted triflic acid. The acidified H2N-SBA-15 161 + 104 etc. is one of effective methods to increase the surface area, and to obtained was designated as H3N-SBA-15. Immobilization of 162 105 separate and recycle the catalysts [32]. Among the porous sub- HPW catalyst on H2N-SBA-15 support was performed by adding 163 + 106 strates, mesoporous SBA-15 is very interesting material due to its of 0.7 g of H3N-SBA-15 into mixture containing 50 mL methanol 164 107 large specific surface area allowing exellent dispersion of catalytic and 0.3 g of HPW. The mixture was refluxed at 65 °C for 5 h before 165 108 active sites. Further, the large pore size of that material can aid the being filtered to obtain solid product, which was dried under vac- 166 109 movement of bulky organic molecules in and out of the pores.