Loading...
3 results
Search Results
Now showing 1 - 3 of 3
- Desulfurization process conciliating heterogeneous oxidation and liquid extraction: Organic solvent or centrifugation/water?Publication . Ribeiro, Susana O.; Nogueira, Lucie S.; Gago, Sandra; Almeida, Pedro L.; Corvo, Marta C.; De Castro, Baltazar; Granadeiro, Carlos; Balula, SaleteThe present work presents a strategic oxidative desulfurization system able to efficiently operate under sustainable conditions, i.e. using an eco-friendly oxidant and without the need of extractive organic solvents. The catalytic performance of Eu(PW11O39)2@aptesSBA-15 was evaluated for the oxidative desulfurization of a multicomponent model diesel using a solvent-free or biphasic systems. The results reveal its remarkable desulfurization performance achieving complete desulfurization after just 2 h of reaction. Moreover, the composite has shown a high recycling ability without loss of catalytic activity for ten consecutive ODS cycles. Interestingly, under solvent-free conditions it was possible to maintain the desulfurization efficiency of the biphasic system while being able to avoid the use of harmful organic solvents. In this case, a successful extraction of oxidized sulfur compounds was found conciliating centrifugation and water as extraction solvent. Therefore, this work reports an important step towards the development of novel eco-sustainable desulfurization systems with high industrial interest.
- Efficient heterogeneous polyoxometalate-hybrid catalysts for the oxidative desulfurization of fuelsPublication . Mirante, Fátima; Dias, Luís; Silva, Mariana; Ribeiro, Susana; Corvo, Marta C.; De Castro, Baltazar; Granadeiro, Carlos; Balula, SaleteThe heterogenization of the highly active monovacant polyoxotungstate ([PW11O39](7-), abbreviated as PW11) was achieved by preparing the corresponding long chain quaternary ammonium salt (ODA(7)PW(11), ODA = CH3(CH2)(17)(CH3)(3)N). The complete cation exchange confers total heterogeneity to the monovacant catalyst while keeping its oxidative catalytic activity. In fact, the heterogeneous catalyst allowed for the complete desulfurization of a multicomponent model diesel (2000 ppm S) after 40 min of reaction, conciliating extraction (using BMIMPF6 solvent) and oxidation (ECODS process using H2O2 oxidant). The heterogeneous catalyst has shown a superior desulfurization performance when compared with the homogeneous quaternary ammonium TBAPW(11) catalyst (TBA = (C4H9)(4) N). Both hybrid catalysts have been successfully reused in consecutive ECODS cycles. Additionally, the long carbon chain cations provide a protective environment around the polyoxometalate allowing for ODA(7)PW(11) to retain its heterogeneity and structure after the ECODS process.
- A novel red emitting material based on polyoxometalate@periodic mesoporous organosilicaPublication . Granadeiro, Carlos; Ribeiro, Susana; Kaczmarek, Anna M.; Cunha-Silva, Luis; Almeida, Pedro L.; Gago, Sandra; Van Deun, Rik; De Castro, Baltazar; Balula, SaleteThe first lanthanopolyoxometalate-supported bifunctional periodic mesoporous organosilica (BPMO) composite is here reported. The incorporation of decatunsgstoeuropate anions ([Eu(W5O18)(2)](9-)) within the porous channels of an ethylene-bridged TIVIAPS-functionalized BPMO produced a luminescent material exhibiting a strong red emission under UV irradiation. Photoluminescence studies showed an efficient energy transfer process to the lanthanide emitting center in the material (antenna effect). A significant change in the coordination environment of Eu3+ ions was observed after its incorporation into the TMAPS-functionalized material. The possible reason for this is discussed within the paper.