Oxidative desulfurization strategies using Keggin-type polyoxometalate catalysts: Biphasic versus solvent-free systems

Ribeiro, Susana; Granadeiro, Carlos M.; Almeida, Pedro L.; Pires, João; Capel-Sanchez, M. Carmen; Campos‐Martín, Jose M.; Gago, Sandra; Castro, Balt­azar de; Balula, Salete S.

doi:10.1016/j.cattod.2018.10.046

Cited by 62 publications

(55 citation statements)

References 56 publications

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“…In all spectra, the signals at −93, −102 and −111 ppm corresponding to Q 2 , Q 3 and Q 4 respectively (Q n = Si(Osi) n (OH) 4-n ) were in accordance with the SiO 2 core [49]. The silane grafting was proved by two signals around −60 and −68 ppm (T 2 and T 3 ) [82]. A change of signals proportion was observed from SiO 2 to SiO 2 @NH 2 and from SiO 2 @NH 2 to SiO 2 @PM, the trend being identical when both POMs were added.…”

Section: Resultsmentioning

confidence: 99%

Organic Solvent-Free Olefins and Alcohols (ep)oxidation Using Recoverable Catalysts Based on [PM12O40]3− (M = Mo or W) Ionically Grafted on Amino Functionalized Silica Nanobeads

2019

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Catalyzed organic solvent-free (ep)oxidation were achieved using H3PM12O40 (M = Mo or W) complexes ionically grafted on APTES-functionalized nano-silica beads obtained from straightforward method (APTES = aminopropyltriethoxysilane). Those catalysts have been extensively analyzed through morphological studies (Dynamic Light Scattering (DLS), TEM) and several spectroscopic qualitative (IR, multinuclear solid-state NMR) and quantitative (1H and 31P solution NMR) methods. Interesting catalytic results were obtained for the epoxidation of cyclooctene, cyclohexene, limonene and oxidation of cyclohexanol with a lower [POM]/olefin ratio. The catalysts were found to be recyclable and reused during three runs with similar catalytic performances.

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Section: Resultsmentioning

confidence: 99%

Organic Solvent-Free Olefins and Alcohols (ep)oxidation Using Recoverable Catalysts Based on [PM12O40]3− (M = Mo or W) Ionically Grafted on Amino Functionalized Silica Nanobeads

2019

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“…The reagents used for the synthesis of the materials and the ODS experiments were purchased to chemical suppliers and used without further purification (Ribeiro et al, 2018b). The materials prepared were characterized as previously described by our group for other mesoporous silica-based composites (Ribeiro et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

“…In ODS, the presence of an active catalyst with proper textural and surface chemical properties, as well as, an appropriate oxidant is the key to the success of this process. The monolacunary [PW 11 O 39 ] 7− Keggin polyoxometalate has shown remarkable performance in oxidative reactions (Casuscelli et al, 2004; Granadeiro et al, 2013; Ribeiro et al, 2013a; Singh et al, 2015; Coronel and da Silva, 2018), which has motivated its application in the oxidative desulfurization of fuels (Abdalla et al, 2009; Abdalla and Li, 2012; Wu et al, 2014; Mirante et al, 2018; Ribeiro et al, 2018b). In this work, novel composites have been prepared through the impregnation of the [PW 11 O 39 ] 7− (PW 11 ) heteropolyanion in silica materials functionalized with N -trimethoxysilypropyl- N, N, N -trimethylammonium (TMA).…”

Section: Introductionmentioning

confidence: 99%

Mesoporous Silica vs. Organosilica Composites to Desulfurize Diesel

et al. 2019

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The monolacunary Keggin-type [PW11O39]7− (PW11) heteropolyanion was immobilized on porous framework of mesoporous silicas, namely SBA-15 and an ethylene-bridged periodic mesoporous organosilica (PMOE). The supports were functionalized with a cationic group (N-trimethoxysilypropyl-N, N, N-trimethylammonium, TMA) for the successful anchoring of the anionic polyoxometalate. The PW11@TMA-SBA-15 and PW11@TMA-PMOE composites were evaluated as heterogeneous catalysts in the oxidative desulfurization of a model diesel. The PW11@TMA-SBA-15 catalyst showed a remarkable desulfurization performance by reaching ultra-low sulfur levels (<10 ppm) after only 60 min using either a biphasic extractive and catalytic oxidative desulfurization (ECODS) system (1:1 MeCN/diesel) or a solvent-free catalytic oxidative desulfurization (CODS) system. Furthermore, the mesoporous silica composite was able to be recycled for six consecutive cycles without any apparent loss of activity. The promising results have led to the application of the catalyst in the desulfurization of an untreated real diesel supplied by CEPSA (1,335 ppm S) using the biphasic system. The system has proved to be a highly efficient process by reaching desulfurization values higher than 90% for real diesel during three consecutive cycles.

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“…Anyway, the easy modification of native SBA-15 surface through a post-grafting procedure, in order to introduce more robust functional group (i.e., APTES to give H2N-SBA-15 or N-(3trimethoxysilylpropyl) tributylammonium to give tba-SBA-15) for the anchoring of different types of HPAs, justifies the large number of published articles appeared in literature, in the last decade. Among them, H2N-SBA-15 and tba-SBA-15 supports were used to heterogenize, through an impregnation method, Keggin-type derivatives like lacunar polyanions [PW11O39] 7− (PW11), resulting by the removal of one WO 4+ unit, or sandwich-type [Eu(PW11O39)2] 11− anion affording robust and active catalysts for the ODS of model oil and real diesel, either under biphasic (diesel/acetonitrile 1:1) or solvent-free conditions [201,202]. Noteworthy, the PW11/H2N-SBA-15 composite system showed to maintain its activity for eight consecutive cycles.…”

Section: Phosphotungstic Containing Pomsmentioning

confidence: 99%

“…In a recent paper, a contribution based on the use of a composite material formed by a phosphorous-containing tetranuclear peroxotungstate {PO4[WO2(O2)2]4} 3 Venturello anion symbolized as PW4, immobilized on trimethylammonium functionalized SBA-15 (PW4/tma-SBA-15) through an impregnation method, employed as catalyst for the ODS of model and real fuels, has been published [206]. Impressive data concerning activity and [201,202]. Noteworthy, the PW 11 /H 2 N-SBA-15 composite system showed to maintain its activity for eight consecutive cycles.…”

Section: Phosphotungstic Containing Pomsmentioning

confidence: 99%

SBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process

2019

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Recalcitrant sulfur compounds are common impurities in crude oil. During combustion they produce SOx derivatives that are able to affect the atmospheric ozone layer, increasing the formation of acid rains, and reducing the life of the engine due to corrosion. In the last twenty years, many efforts have been devoted to develop conventional hydrodesulfurization (HDS) procedures, as well as alternative methods, such as selective adsorption, bio-desulfurization, oxidative desulfurization (ODS) under extractive conditions (ECODS), and others. Among them, the oxidative procedures have been usually accomplished by the use of toxic stoichiometric oxidants, namely potassium permanganate, sodium bromate and carboxylic and sulfonic peracids. As an alternative, increasing interest is devoted to selective and economical procedures based upon catalytic methods. Heterogeneous catalysis is of relevance in industrial ODS processes, since it reduces the leaching of active species and favors the recovery and reuse of the catalyst for successive transformations. The heterogenization of different types of high-valent metal transition-based organometallic complexes, able to promote the activation of stoichiometric benign oxidants like peroxides, can be achieved using various solid supports. Many successful cases have been frequently associated with the use of mesoporous silicas that have the advantage of easy surface modification by reaction with organosilanes, facilitating the immobilization of homogeneous catalysts. In this manuscript the application of SBA-15 as efficient support for different active metal species, able to promote the catalytic ODS of either model or real fuels is reviewed, highlighting its beneficial properties such as high surface area, narrow pore size distribution and tunable pore diameter dimensions. Related to this topic, the most relevant advances recently published, will be discussed and critically described.

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Oxidative desulfurization strategies using Keggin-type polyoxometalate catalysts: Biphasic versus solvent-free systems

Cited by 62 publications

References 56 publications

Organic Solvent-Free Olefins and Alcohols (ep)oxidation Using Recoverable Catalysts Based on [PM12O40]3− (M = Mo or W) Ionically Grafted on Amino Functionalized Silica Nanobeads

Organic Solvent-Free Olefins and Alcohols (ep)oxidation Using Recoverable Catalysts Based on [PM12O40]3− (M = Mo or W) Ionically Grafted on Amino Functionalized Silica Nanobeads

Mesoporous Silica vs. Organosilica Composites to Desulfurize Diesel

SBA-15 Anchored Metal Containing Catalysts in the Oxidative Desulfurization Process

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