resumo
Different methodologies were used to increase the oxidative desulfurization efficiency of the Keggin phosphotungstate [PW12O40](3-) (PW12). One possibility was to replace the acid proton by three different ionic liquid cations, forming the novel hybrid polyoxometalates: [BMIM](3)PW12 (BMIM as 1-butyl-3-methylimidazolium), [BPy](3)PW12 (BPy as 1-butylpyridinium) and [HDPy](3)PW12 (HDPy as hexadecylpyridinium. These hybrid Keggin compounds showed high oxidative desulfurization efficiency in the presence of [BMIM]PF6 solvent, achieving complete desulfurization of multicomponent model diesel (2000 ppm of S) after only 1 h, using a low excess of oxidant (H2O2 /S = 8) at 70 degrees C. However, their stability and activity showed some weakness in continuous reused oxidative desulfurization cycles. An improvement of stability in continuous reused cycles was reached by the immobilization of the Keggin polyanion in a strategic positively-charged functionalized-SBA-15 support. The PW12@TM-SBA-15 composite (TM is the trimethylammonium functional group) presented similar oxidative desulfurization efficiency to the homogeneous IL-PW12 compounds, having the advantage of a high recycling capability in continuous cycles, increasing its activity from the first to the consecutive cycles. Therefore, the oxidative desulfurization system catalyzed by the Keggin-type composite has high performance under sustainable operational conditions, avoids waste production during recycling and allows catalyst recovery.
palavras-chave
METAL-ORGANIC FRAMEWORKS; DEEP DESULFURIZATION; MESOPOROUS SILICA; HETEROGENEOUS CATALYSTS; MODEL DIESEL; POLYOXOMETALATE; EPOXIDATION; HYBRID; ODS; EXTRACTION
categoria
Materials Science
autores
Ribeiro, SO; Duarte, B; de Castro, B; Granadeiro, CM; Balula, SS
nossos autores
Carlos Miguel Cardeal Enes Granadeiro
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
This work was partly funded through the project REQUIMTE-LAQV, POCI-01-0145-FEDER-007265 [FCT (Fundacao para a Ciencia e a Tecnologia) Ref. UID/QUI/50006/2013] financed by national funds through the FCT/MEC and, when appropriate, co-financed by the FEDER (Fundo Europeu de Desenvolvimento Regional) under the PT2020 Partnership Agreement. The FCT and the European Union are acknowledged for post-graduation grants to S.O.R. (SFRH/BD/95571/2013) and C.M.G. (SFRH/BPD/109253/2015) co-funded by MCTES and the European Social Fund through the program POPH of QREN.