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2020
Roma-Rodrigues, C, Malta G, Peixoto D, Ferreira LM, Baptista PV, Fernandes AR, Branco PS.  2020.  Synthesis of new hetero-arylidene-9(10H)-anthrone derivatives and their biological evaluation, 2020. Bioorg Chem. 99:103849. AbstractWebsite

New hetero-arylidene-9(10H)-anthrone derivatives (1) were synthesized from reaction of 1,2-dimethyl-3-alkyl imidazolium salts (2) and 9-anthracenecarboxaldehyde. Ion exchange of the anion with dioctyl sulfosuccinate and lithium bis(trifluoromethanesulfonyl)imide led to the preparation of other derivatives. The antiproliferative effect of the compounds was evaluated in human ovarian (A2780) and colorectal (HCT116) carcinoma cell lines and in normal primary human fibroblasts. Compound 1 presented an antiproliferative effect related to the imidazolium pattern of substitution with compounds having a decyl group at the R-position (1c and 3c) showing the highest cytotoxic activities in all cell lines independently of the counter ion. Compounds 1b and 1c internalize A2780 cancer cells via a passive or an active transport, respectively, inducing A2780 cell death via an extrinsic apoptosis (1b) or intrinsic apoptosis and oncosis (1c). The localization of both compounds in the cytoplasm coupled to the absence of reactive oxygen species (ROS) induction suggest that the mechanisms of toxicity might be different than those of other anthracyclines currently used in chemotherapy.

Alves-Barroco, C, Rivas-Garcia L, Fernandes AR, Baptista PV.  2020.  Tackling Multidrug Resistance in Streptococci - From Novel Biotherapeutic Strategies to Nanomedicines, 2020. Front Microbiol. 11:579916. AbstractWebsite

The pyogenic streptococci group includes pathogenic species for humans and other animals and has been associated with enduring morbidity and high mortality. The main reason for the treatment failure of streptococcal infections is the increased resistance to antibiotics. In recent years, infectious diseases caused by pyogenic streptococci resistant to multiple antibiotics have been raising with a significant impact to public health and veterinary industry. The rise of antibiotic-resistant streptococci has been associated to diverse mechanisms, such as efflux pumps and modifications of the antimicrobial target. Among streptococci, antibiotic resistance emerges from previously sensitive populations as result of horizontal gene transfer or chromosomal point mutations due to excessive use of antimicrobials. Streptococci strains are also recognized as biofilm producers. The increased resistance of biofilms to antibiotics among streptococci promote persistent infection, which comprise circa 80% of microbial infections in humans. Therefore, to overcome drug resistance, new strategies, including new antibacterial and antibiofilm agents, have been studied. Interestingly, the use of systems based on nanoparticles have been applied to tackle infection and reduce the emergence of drug resistance. Herein, we present a synopsis of mechanisms associated to drug resistance in (pyogenic) streptococci and discuss some innovative strategies as alternative to conventional antibiotics, such as bacteriocins, bacteriophage, and phage lysins, and metal nanoparticles. We shall provide focused discussion on the advantages and limitations of agents considering application, efficacy and safety in the context of impact to the host and evolution of bacterial resistance.

Oliveira, AR, Mota C, Mourato C, Domingos RM, Santos MFA, Gesto D, Guigliarelli B, Santos-Silva T, Romão MJ, Pereira IAC.  2020.  Towards the mechanistic understanding of enzymatic CO2 reduction, 2020. ACS CatalysisACS Catalysis. : American Chemical Society AbstractWebsite

Reducing CO2 is a challenging chemical transformation that biology solves easily, with high efficiency and specificity. In particular, formate dehydrogenases are of great interest since they reduce CO2 to formate, a valuable chemical fuel and hydrogen storage compound. The metal-dependent formate dehydrogenases of prokaryotes can show high activity for CO2 reduction. Here, we report an expression system to produce recombinant W/Sec-FdhAB from Desulfovibrio vulgaris Hildenborough fully loaded with cofactors, its cata-lytic characterization and crystal structures in oxidised and reduced states. The enzyme has very high activi-ty for CO2 reduction and displays remarkable oxygen stability. The crystal structure of the formate-reduced enzyme shows Sec still coordinating the tungsten, supporting a mechanism of stable metal coordination during catalysis. Comparison of the oxidised and reduced structures shows significant changes close to the active site. The DvFdhAB is an excellent model for studying catalytic CO2 reduction and probing the mecha-nism of this conversion.Reducing CO2 is a challenging chemical transformation that biology solves easily, with high efficiency and specificity. In particular, formate dehydrogenases are of great interest since they reduce CO2 to formate, a valuable chemical fuel and hydrogen storage compound. The metal-dependent formate dehydrogenases of prokaryotes can show high activity for CO2 reduction. Here, we report an expression system to produce recombinant W/Sec-FdhAB from Desulfovibrio vulgaris Hildenborough fully loaded with cofactors, its cata-lytic characterization and crystal structures in oxidised and reduced states. The enzyme has very high activi-ty for CO2 reduction and displays remarkable oxygen stability. The crystal structure of the formate-reduced enzyme shows Sec still coordinating the tungsten, supporting a mechanism of stable metal coordination during catalysis. Comparison of the oxidised and reduced structures shows significant changes close to the active site. The DvFdhAB is an excellent model for studying catalytic CO2 reduction and probing the mecha-nism of this conversion.

Das, K, Datta A, Frontera A, Wen YS, Roma-Rodrigues C, Raposo LR, Fernandes AR, Hung CH.  2020.  Zn(II) and Co(II) derivatives anchored with scorpionate precursor: Antiproliferative evaluation in human cancer cell lines, 2020. J Inorg Biochem. 202:110881. AbstractWebsite

A 'scorpionate' type precursor [bdtbpza=bis(3,5-di-t-butylpyrazol-1-yl)acetate] has been employed to synthesize two mononuclear Zn(II) and Co(II) derivatives, namely [Zn(bdtbpza)2 (H2O)2].2.5CH3OH.2[(CH3)3C-C3H2N2-C(CH3)3] (1) and [Co(bdtbpza)2(CH3OH)4] (2) in good yield. Single crystal X-ray diffraction analysis reveals that in 1, the Zn(II) atom is tetrahedrally surrounded by a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units and two water molecules; while in 2, the Co(II) atom shows an octahedral environment coordinating a pair of Oacetate atoms of two bis(pyrazol-1-yl)acetate units along with four methanol molecules. The EPR spectra of 2 recorded at 77 and 298K confirmed the tetragonal symmetry of the high spin Co(II). The DFT (Density functional theory) computation is in good agreement with the geometry proposed for compounds 1 and 2. Both the compounds display a high antiproliferative activity against HCT116 (colorectal carcinoma) and A2780 (ovarian carcinoma) cell lines compared to human normal dermal fibroblasts. In the case of A2780 cells, compounds 1 and 2 exhibit IC50 values that are similar to those described for cisplatin, a widely used chemotherapeutic drug. Exposure of A2780 cells to the IC50 concentration of each compound led to an increase of the number of apoptotic and autophagic cells. In the case of compound 1, the accumulation of intracellular ROS (Reactive oxygen species) is responsible for triggering A2780 cell death.

Pacheco, V, Araújo N, Rocha L.  2020.  PRODUTECH SIF Project: its mobilized effect and main results and its contribution to accelerating digital transformation in the industry, 2-4 Oct. 2020. 8th International Conference on Virtual and Networked Organizations Emergent Technologies and Tools - ViNOrg'20. , Guimarães, Portugal: Universidade do Minho
Pacheco, V, Araújo N, Rocha L.  2020.  Smart Additive Manufacturing: the path to digital chain, 2-4 Oct. 2020. 8th International Conference on Virtual and Networked Organizations Emergent Technologies and Tools - ViNOrg'20. , Guimarães, Portugal: Universidade do Minho
Roque, ACA, Pina AS, Azevedo AM, Aires-Barros R, Jungbauer A, Profio DG, Heng JYY, Haigh J, Ottens M.  2020.  Anything but Conventional Chromatography Approaches in Bioseparation. Biotechnology Journal. (e1900274):1-8.
dos Santos, R, Iria I, Manuel AM, Leandro AP, Madeira CAC, Gonçalves J, Carvalho AL, Roque ACA.  2020.  Magnetic Precipitation: A New Platform for Protein Purification. Biotechnology Journal. 15(9):2000151.
Rebordão, G, Palma SICJ, Roque ACA.  2020.  Microfluidics in Gas Sensing and Artificial Olfaction. Sensors . 20(20):5742. AbstractPDF

Rapid, real-time, and non-invasive identification of volatile organic compounds (VOCs)
and gases is an increasingly relevant field, with applications in areas such as healthcare, agriculture,
or industry. Ideal characteristics of VOC and gas sensing devices used for artificial olfaction include
portability and affordability, low power consumption, fast response, high selectivity, and sensitivity.
Microfluidics meets all these requirements and allows for in situ operation and small sample amounts,
providing many advantages compared to conventional methods using sophisticated apparatus such
as gas chromatography and mass spectrometry. This review covers the work accomplished so far
regarding microfluidic devices for gas sensing and artificial olfaction. Systems utilizing electrical
and optical transduction, as well as several system designs engineered throughout the years are
summarized, and future perspectives in the field are discussed.

Fernandes, CSM, Rodrigues AL, Alves VD, Fernandes TG, Pina AS, Roque ACA.  2020.  Natural multimerization rules the performance of affinity-based physical hydrogels for stem cell encapsulation and differentiation. Biomacromolecules. 8(21):3081–3091.
Matos, MJB, Pina AS, Roque ACA.  2020.  Rational design of affinity ligands for bioseparation. Journal of Chromatography A. (460871)
Inácio, M, Isufi B, Lapi M, Ramos AP.  2020.  Rational Use of High-Strength Concrete in Flat Slab-Column Connections under Seismic Loading. ACI Structural Journal. 117(6) Abstractmanuscript_aci_accepted.pdfWebsite

High Strength Concrete (HSC) slab–column connections with relatively low concrete strengths compared to today’s capabilities have been tested under seismic-type loading in the past. Herein, the hybrid use of HSC with compressive strength around 120 MPa and Normal Strength Concrete (NSC) is investigated through three reversed horizontal cyclic loading tests with different geometries of the HSC region and a reference NSC specimen. The results show that HSC applied in the vicinity of the column can significantly enhance the seismic performance of slab–column connections. The best result in terms of drift capacity and economic use of HSC was achieved in the case of full-depth HSC extended from the column’s face up to 2.5 times the effective depth. Drift ratios up to 3.0% were achieved. A comparison with previous tests showed that the hybrid use of HSC and NSC can achieve similar results to the provision of punching shear reinforcement.

Esteves, C, Ramou E, Porteira ARP, Barbosa AJM, Roque ACA.  2020.  Seeing the Unseen: The Role of Liquid Crystals in Gas‐Sensing Technologies. Advanced Optical Materials. 1902117:1-29. AbstractPDF

Fast, real-time detection of gases and volatile organic compounds (VOCs) is
an emerging research field relevant to most aspects of modern society, from
households to health facilities, industrial units, and military environments.
Sensor features such as high sensitivity, selectivity, fast response, and low
energy consumption are essential. Liquid crystal (LC)-based sensors fulfill
these requirements due to their chemical diversity, inherent self-assembly
potential, and reversible molecular order, resulting in tunable stimuliresponsive soft materials. Sensing platforms utilizing thermotropic uniaxial
systems—nematic and smectic—that exploit not only interfacial phenomena,
but also changes in the LC bulk, are demonstrated. Special focus is given to
the different interaction mechanisms and tuned selectivity toward gas and
VOC analytes. Furthermore, the different experimental methods used to
transduce the presence of chemical analytes into macroscopic signals are discussed and detailed examples are provided. Future perspectives and trends
in the field, in particular the opportunities for LC-based advanced materials in
artificial olfaction, are also discussed.

Rodrigues, R, Palma SICJ, Correia VJ, Padrao I, Pais J, Banza M, Alves C, Deuermeier J, Martins C, Costa HMA, Ramou E, Silva Pereira C, Roque ACA.  2020.  Sustainable plant polyesters as substrates for optical gas sensors. Materials Today Bio. 8:100083. AbstractPDF

The fast and non-invasive detection of odors and volatile organic compounds (VOCs) by gas sensors and electronic
noses is a growing field of interest, mostly due to a large scope of potential applications. Additional drivers for the
expansion of the field include the development of alternative and sustainable sensing materials. The discovery
that isolated cross-linked polymeric structures of suberin spontaneously self-assemble as a film inspired us to
develop new sensing composite materials consisting of suberin and a liquid crystal (LC). Due to their stimuliresponsive and optically active nature, liquid crystals are interesting probes in gas sensing. Herein, we report
the isolation and the chemical characterization of two suberin types (from cork and from potato peels) resorting to
analyses of gas chromatography–mass spectrometry (GC-MS), solution nuclear magnetic resonance (NMR), and Xray photoelectron spectroscopy (XPS). The collected data highlighted their compositional and structural differences. Cork suberin showed a higher proportion of longer aliphatic constituents and is more esterified than potato
suberin. Accordingly, when casted it formed films with larger surface irregularities and a higher C/O ratio. When
either type of suberin was combined with the liquid crystal 5CB, the ensuing hybrid materials showed distinctive
morphological and sensing properties towards a set of 12 VOCs (comprising heptane, hexane, chloroform,
toluene, dichlormethane, diethylether, ethyl acetate, acetonitrile, acetone, ethanol, methanol, and acetic acid).
The optical responses generated by the materials are reversible and reproducible, showing stability for 3 weeks.
The individual VOC-sensing responses of the two hybrid materials are discussed taking as basis the chemistry of
each suberin type. A support vector machines (SVM) algorithm based on the features of the optical responses was
implemented to assess the VOC identification ability of the materials, revealing that the two distinct suberin-based
sensors complement each other, since they selectively identify distinct VOCs or VOC groups. It is expected that
such new environmentally-friendly gas sensing materials derived from natural diversity can be combined in arrays
to enlarge selectivity and sensing capacity.

Santos, Â, Otero V, Rodrigues B, Vilarigues M.  2020.  Unravelling the Secrets of Magic Lantern Slide Painting. The Magic Lantern. 22(March 2020):10-12.Website
Padrão, I, Fernandes CSM, Esteves C, Fernandes T, Pina AS, Roque ACA.  2020.  Versatile and Tunable Poly(Ethylene Glycol)‐Based Hydrogels Crosslinked through the Ugi Reaction. ChemPlusChem. 85(12):2737-2741.
Rodrigues, ARF, Maia MRG, Cabrita ARJ, Oliveira HM, Bernardo M, Lapa N, Fonseca I, Trindade H, Pereira JL, Fonseca AJM.  2020.  Assessment of potato peel and agro-forestry biochars supplementation on in vitro ruminal fermentation. PeerJ. 8:e9488. AbstractWebsite

Background The awareness of environmental and socio-economic impacts caused by greenhouse gas emissions from the livestock sector leverages the adoption of strategies to counteract it. Feed supplements can play an important role in the reduction of the main greenhouse gas produced by ruminants—methane (CH\textsubscript{4}). In this context, this study aims to assess the effect of two biochar sources and inclusion levels on rumen fermentation parameters \textit{in vitro}. Methods Two sources of biochar (agro-forestry residues, AFB, and potato peel, PPB) were added at two levels (5 and 10%, dry matter (DM) basis) to two basal substrates (haylage and corn silage) and incubated 24-h with rumen inocula to assess the effects on CH\textsubscript{4} production and main rumen fermentation parameters \textit{in vitro}. Results AFB and PPB were obtained at different carbonization conditions resulting in different apparent surface areas, ash content, pH at the point of zero charge (pHpzc), and elemental analysis. Relative to control (0% biochar), biochar supplementation kept unaffected total gas production and yield (mL and mL/g DM, \textit{p} = 0.140 and \textit{p} = 0.240, respectively) and fermentation pH (\textit{p} = 0.666), increased CH\textsubscript{4}production and yield (mL and mL/g DM, respectively, \textit{p} = 0.001) and ammonia-N (NH\textsubscript{3}-N, \textit{p} = 0.040), and decreased total volatile fatty acids (VFA) production (\textit{p} < 0.001) and H\textsubscript{2} generated and consumed (\textit{p} ≤ 0.001). Biochar sources and inclusion levels had no negative effect on most of the fermentation parameters and efficiency. Acetic:propionic acid ratio (\textit{p} = 0.048) and H\textsubscript{2} consumed (\textit{p} = 0.019) were lower with AFB inclusion when compared to PPB. Biochar inclusion at 10% reduced H\textsubscript{2} consumed (\textit{p} < 0.001) and tended to reduce total gas production (\textit{p} = 0.055). Total VFA production (\textit{p} = 0.019), acetic acid proportion (\textit{p} = 0.011) and H\textsubscript{2} generated (\textit{p} = 0.048) were the lowest with AFB supplemented at 10%, no differences being observed among the other treatments. The basal substrate affected most fermentation parameters independently of biochar source and level used. Discussion Biochar supplementation increased NH\textsubscript{3}-N content, \textit{iso}-butyric, \textit{iso}-valeric and valeric acid proportions, and decreased VFA production suggesting a reduced energy supply for microbial growth, higher proteolysis and deamination of substrate N, and a decrease of NH\textsubscript{3}-N incorporation into microbial protein. No interaction was found between substrate and biochar source or level on any of the parameters measured. Although AFB and PPB had different textural and compositional characteristics, their effects on the rumen fermentation parameters were similar, the only observed effects being due to AFB included at 10%. Biochar supplementation promoted CH\textsubscript{4} production regardless of the source and inclusion level, suggesting that there may be other effects beyond biomass and temperature of production of biochar, highlighting the need to consider other characteristics to better identify the mechanism by which biochar may influence CH\textsubscript{4} production.

Rijo, B, Lemos F, Fonseca I, Vilelas A.  2020.  Development of a model for an industrial acetylene hydrogenation reactor using plant data – Part I. Chemical Engineering Journal. 379:122390. AbstractWebsite

In this work, a dynamic model of an industrial acetylene hydrogenation reactor with a front-end configuration was developed, based on plant operation data. This type of reactor operates in transient state, not only due to the natural fluctuations in operating conditions but also due to the effects caused by the deactivation of the catalyst. To develop the dynamic model of the acetylene hydrogenation reactor a thorough study of the effect of operating conditions was performed; the influence of variables such as the inlet temperature of the 1st reactor, the flowrate, carbon monoxide concentration, on the activity, selectivity and stability of the catalyst was examined by choosing adequate periods of the operation of the reactor. To understand the reaction mechanism of this system, several published kinetics were tested but only one was finally fitted to the industrial data, to interpret the operation of the acetylene hydrogenation reactor. A set of operation periods was used to develop the model which was then validated by applying the model to a different set of operation periods. As a conclusion, the dynamic model that was developed and validated, using actual plant operation data, was able to adequately describe the outlet temperatures of the three reactors in the system as well as the outlet acetylene concentration of the 3rd reactor.

Castanheiro, JE, Vital J, Fonseca IM, Ramos AM.  2020.  Glycerol conversion into biofuel additives by acetalization with pentanal over heteropolyacids immobilized on zeolites. Catalysis Today. 346:76-80. AbstractWebsite

Dodecamolydbophosphoric acid (HPMo) immobilized on USY zeolite was used as a catalyst for the acetalization of glycerol with pentanal at 70 °C. Catalysts were prepared with different amounts of heteropolyacid, and the most active sample was the HPMo2@Y catalyst (1.1 wt.%). The products of glycerol acetalization with pentanal were (2-butyl-1,3-dioxolan-4-yl)methanol, a five-member ring compound, and 2-butyl-1,3-dioxan-5-ol, a six-member ring compound. Good values of selectivity for the five-member ring compound (80–85%) were obtained with all materials. The reaction conditions were optimized using HPMo2@Y as a catalyst. The optimal conditions were determined to be 70 °C reaction temperature with 0.3 g catalyst and a 1:2.5 M ratio of glycerol to pentanal. The catalytic stability of HPMo2@Y was studied. The acetalization of glycerol with pentanal was performed using the same sample. High catalytic activity for HPMo2@Y was observed.

Ribeiro, DO, Viegas A, Pires VMR, Medeiros-Silva J, Bule P, Chai W, Marcelo F, Fontes CMGA, Cabrita EJ, Palma AS, Carvalho AL.  2020.  Molecular basis for the preferential recognition of β1,3-1,4-glucans by the family 11 carbohydrate-binding module from Clostridium thermocellum. The FEBS Journal. 287:2723-2743., Number 13 AbstractWebsite

Understanding the specific molecular interactions between proteins and β1,3-1,4-mixed-linked d-glucans is fundamental to harvest the full biological and biotechnological potential of these carbohydrates and of proteins that specifically recognize them. The family 11 carbohydrate-binding module from Clostridium thermocellum (CtCBM11) is known for its binding preference for β1,3-1,4-mixed-linked over β1,4-linked glucans. Despite the growing industrial interest of this protein for the biotransformation of lignocellulosic biomass, the molecular determinants of its ligand specificity are not well defined. In this report, a combined approach of methodologies was used to unravel, at a molecular level, the ligand recognition of CtCBM11. The analysis of the interaction by carbohydrate microarrays and NMR and the crystal structures of CtCBM11 bound to β1,3-1,4-linked glucose oligosaccharides showed that both the chain length and the position of the β1,3-linkage are important for recognition, and identified the tetrasaccharide Glcβ1,4Glcβ1,4Glcβ1,3Glc sequence as a minimum epitope required for binding. The structural data, along with site-directed mutagenesis and ITC studies, demonstrated the specificity of CtCBM11 for the twisted conformation of β1,3-1,4-mixed-linked glucans. This is mediated by a conformation–selection mechanism of the ligand in the binding cleft through CH-π stacking and a hydrogen bonding network, which is dependent not only on ligand chain length, but also on the presence of a β1,3-linkage at the reducing end and at specific positions along the β1,4-linked glucan chain. The understanding of the detailed mechanism by which CtCBM11 can distinguish between linear and mixed-linked β-glucans strengthens its exploitation for the design of new biomolecules with improved capabilities and applications in health and agriculture. Database Structural data are available in the Protein Data Bank under the accession codes 6R3M and 6R31.

Bernardo, M, Correa CR, Ringelspacher Y, Becker GC, Lapa N, Fonseca I, Esteves IAAC, Kruse A.  2020.  Porous carbons derived from hydrothermally treated biogas digestate. Waste Management. 105:170-179. AbstractWebsite

Porous carbons from digestate-derived hydrochar were produced, characterized and their performance to reclaim phosphate from water was evaluated as a preliminary approach to demonstrate their practical application. In a first step, the digestate was converted into hydrochars through hydrothermal carbonization by using two different pH conditions: 8.3 (native conditions) and 3.0 (addition of H2SO4). The resulting hydrochars did not present significant differences. Consecutively, the hydrochars were activated with KOH to produce activated carbons with enhanced textural properties. The resulting porous carbons presented marked differences: the AC native presented a lower ash content (20.3 wt%) and a higher surface area (SBET = 1106 m2/g) when compared with the AC-H2SO4 (ash content = 43.7 wt% SBET = 503 m2/g). Phosphorus, as phosphate, is a resource present in significative amount in wastewater, causing serious problems of eutrophication. Therefore, the performance of the porous carbons samples to recover phosphate – P(PO43−) – from water was evaluated through exploitation assays that included kinetic studies. The lumped model presented a good fitting to the kinetic data and the obtained uptake capacities were the same for both carbons, 12 mg P(PO43−)/g carbon. Despite the poorer textural properties of AC-H2SO4, this carbon was richer in Ca, Al, Fe, K, and Mg cations which promoted the formation of mineral complexes with phosphate anions. The results obtained in this work are promising for the future development of P(PO43−) enriched carbons that can be used thereafter as biofertilizers in soil amendment applications.

Outis, M, Rosa V, Laia CAT, Lima JC, Barroso S, Carvalho AL, Calhorda MJ, Avilés T.  2020.  Synthesis, Crystal Structure, and DFT Study of Two New Dinuclear Copper(I) Complexes Bearing Ar-BIAN Ligands Functionalized with NO2 Groups. European Journal of Inorganic Chemistry. 2020:2900-2911., Number 30 AbstractWebsite

{Two new bis(aryl-imino)-acenaphthene, Ar-BIAN (Ar = 2

2019
Ribeiro, SO, Granadeiro CM, Almeida PL, Pires J, Valenca R, Campos-Martin JM, Ribeiro JC, de Castro B, Balula SS.  2019.  Effective Zinc-Substituted Keggin Composite To Catalyze the Removal of Sulfur from Real Diesels under a Solvent-Free System, {OCT 9}. Industrial & Engineering Chemistry Research. 58:18540-18549., Number {40} AbstractWebsite

{The Keggin phosphotungstate (PW12) and its zinc derivative (PW11Zn) were tested as oxidative catalysts for desulfurization processes using simulated and real diesels. These compounds were used as homogeneous catalysts, while the corresponding SBA-15 composites were used as heterogeneous catalysts. The comparison of their catalytic performance demonstrated that the zinc-substituted polyoxo-metalate is more efficient than the plenary PW12 structure. Additionally, using the heterogeneous PW11Zn@aptesSBA-15, the sustainability and catalytic efficiency was largely improved, allowing the total sulfur removal from model diesel after 1 h using a small amount of oxidant (H2O2/S = 4) under an oxidative solvent-free system. The desulfurization of real diesels was performed under similar conditions, achieving 87.8% of efficiency using the PW11Zn@aptesSBA-15 catalyst. Furthermore, the catalyst maintained its activity over consecutive desulfurization cycles. The cost-effective operational conditions achieved with PW11Zn@aptesSBA-15 turn this into a promising material to be used in an industrial scale to treat diesel.}

Ribeiro, SO, Granadeiro CM, Almeida PL, Pires J, Capel-Sanchez MC, Campos-Martin JM, Gago S, de Castro B, Balula SS.  2019.  Oxidative desulfurization strategies using Keggin-type polyoxometalate catalysts: Biphasic versus solvent-free systems, {AUG 1}. Catalysis Today. 333:226-236., Number {SI} AbstractWebsite

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.

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