Oxidative desulfurization strategies using Keggin-type polyoxometalate catalysts: Biphasic versus solvent-free systems
authors Ribeiro, SO; Granadeiro, CM; Almeida, PL; Pires, J; Capel-Sanchez, MC; Campos-Martin, JM; Gago, S; de Castro, B; Balula, SS
nationality International
journal CATALYSIS TODAY
author keywords Oxidative desulfurization; Real diesel; Heterogeneous catalysis; Polyoxotungstates; Hydrogen peroxide
keywords MESOPOROUS SILICA; HYBRID MATERIALS; SBA-15; PERFORMANCE; EPOXIDATION; DIESEL; MODEL; POLYOXOTUNGSTATES; DIBENZOTHIOPHENE; ESTERIFICATION
abstract Strategic polyoxometalate Keggin-type structural modification was performed to increase the oxidative catalytic performance to desulfurize model and real diesels. The most active lacunar structure [PW11O39](7-) (PW11) showed to complete desulfurize a simulated diesel after 60 min at 70 degrees C. Its application as homogeneous catalyst using a biphasic system 1: 1 diesel/acetonitrile needed to use an excess of oxidant (ratio H2O2/S = 8). The immobilization of the PW11 on amine-functionalized SBA-15 supports originated two heterogeneous catalysts PW11@aptesSBA-15 and PW11@tbaSBA-15. The best results were attained with the PW11@aptesSBA-15 catalyst showing identical oxidative desulfurization performance as the homogeneous analogue. As advantage, this heterogeneous catalyst promotes the complete desulfurization of simulated diesel using a solvent-free system, i.e. without the need of acetonitrile use. On the other hand, the same desulfurization efficiency could be achieved using half the amount of oxidant (H2O2/S = 4). The oxidative desulfurization of the real diesel achieved a remarkable 83.4% of efficiency after just 2 h. The recycling capacity of PW11@aptesSBA-15 catalyst was confirmed for eight consecutive cycles using the biphasic and the solvent-free systems. Its stability investigation demonstrates to be higher under the solvent-free system than the biphasic system, without practically any occurrence of PW11 leaching in the first case. On the other hand, the Venturello peroxocomplex [PO4{W(O-2)(2)}(4)](3-), recognized as active intermediate in the homogeneous biphasic system, was not identified in the heterogeneous catalytic systems.
publisher ELSEVIER SCIENCE BV
issn 0920-5861
year published 2019
volume 333
beginning page 226
ending page 236
digital object identifier (doi) 10.1016/j.cattod.2018.10.046
web of science category Chemistry, Applied; Chemistry, Physical; Engineering, Chemical
subject category Chemistry; Engineering
unique article identifier WOS:000470828100030
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journal impact factor 4.667
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