Search

[EN] 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 [PWO] (PW) showed to complete desulfurize a simulated diesel after 60 min at 70 °C. Its application as homogeneous catalyst using a biphasic system 1:1 diesel/acetonitrile needed to use an excess of oxidant (ratio HO/S = 8). The immobilization of the PW on amine-functionalized SBA-15 supports originated two heterogeneous catalysts PW@aptesSBA-15 and PW@tbaSBA-15. The best results were attained with the PW@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 (HO/S = 4). The oxidative desulfurization of the real diesel achieved a remarkable 83.4% of efficiency after just 2 h. The recycling capacity of PW@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 PW leaching in the first case. On the other hand, the Venturello peroxocomplex [PO{W(O)} ], recognized as active intermediate in the homogeneous biphasic system, was not identified in the heterogeneous catalytic systems., This work was partly funded through the projects REQUIMTE-LAQV[FCT (Fundação para a Ciência e a Tecnologia) Ref. LAQV, REQUIMTE(POCI-01-0145-FEDER 007265, UID/QUI/50006/2013)] and CENIMAT, I3N (POCI-01-0145-FEDER-007688, UID/CTM/50025/2013) and UID/MULTI/00612/2013 (CQB),financed by national fundsthrough the FCT/MEC and when appropriate co-financed by the Fundo Europeu de Desenvolvimento Regional (FEDER) under the PT2020Partnership Agreement. The FCT and the European Union are ac-knowledged for the post-graduation grants SFRH/BD/95571/2013 (toSOR) and SFRH/BPD/73191/2010 (to CMG) co-funded by Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) and the European Social Fund through the program POPH of QREN. The authors alsoacknowledge the Portuguese Nuclear Magnetic Resonance Network (PTNMR).

A non-chemically amplified negative-tone electron-beam resist with an extremely high sensitivity is presented in this work. The resist, poly(2-hydroxyethyl methacrylate-co-2-methacrylamidoethyl methacrylate) (P(HEMA-co-MAAEMA)), has been synthesized using free radical polymerization of 2-hydroxyethyl methacrylate and 2-aminoethyl methacrylate, and exhibits a crosslinking threshold dose as low as 0.5 μC cm−2. Exposed resist patterns show good adherence to silicon substrates without the assistance of adhesion promoters or thermal treatments and are shown to be adequate for use as a mask for both wet and dry etching of Si. A low contrast value of 1.2 has been measured, indicating that the synthesized polymeric mixture is particularly suitable for achieving grey (3D) lithography. Other relevant properties of the new e-beam resist are optical transparency, visible photoluminescence when crosslinked at low electronic doses, and dose-dependent dual-tone behaviour., The authors gratefully acknowledge financial support from MICINN (TEC2010-10804-E, CTQ2009-14565-C03-03 and TEC2008-06574-C03-03), and the Moncloa Campus of International Excellence (CEI).

The use of amorphous silica-supported titanium catalysts in which the titanium ions display a chemical environment similar to that of Ti-substituted zeolites, afforded excellent activity in the epoxidation of terminal linear and bulky alkenes with dilute solutions of hydrogen peroxide.